Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 24
Filtrar
Más filtros

Banco de datos
País/Región como asunto
Tipo del documento
País de afiliación
Intervalo de año de publicación
1.
Int J Cancer ; 148(3): 692-701, 2021 02 01.
Artículo en Inglés | MEDLINE | ID: mdl-32700765

RESUMEN

Although receptor status including estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2) of the primary breast tumors was related to the prognosis of breast cancer patients, little information is yet available on whether patient management and survival are impacted by receptor conversion in breast cancer metastases. Using data from the nation-wide multicenter clinical epidemiology study of advanced breast cancer in China (NCT03047889), we report the situation of retesting ER, PR and HER2 status for breast cancer metastases and evaluate the patient management and prognostic value of receptor conversion. In total, 3295 patients were analyzed and 1583 (48.0%) patients retesting receptor status for metastasis. Discordance in one or more receptors between the primary and the metastatic biopsy was found in 37.7% of women. Patients who remained hormone receptor (HR) positive in their metastases had similar progression-free survival of first-line and second-line treatment compared to patients with HR conversion (P > .05). In multivariate analysis, patients who showed ER conversion from negative to positive had longer disease-free survival (DFS) than patients who remained negative in their metastases (hazard ratio, 2.05; 95% confidence interval [CI], 1.45-2.90; P < .001). Patients with PR remained positive and had longer DFS than patients with PR conversion from negative to positive (hazard ratio, 0.56; 95% CI, 0.38-0.83; P = .004). Patients with PR conversion have shorter overall survival than patients with PR remained positive or negative (P = .016 and P = .041, respectively). Our findings showed that the receptors' conversions were common in metastatic breast cancer, and the conversion impacted the survival.


Asunto(s)
Neoplasias de la Mama/mortalidad , Receptor ErbB-2/metabolismo , Receptores de Estrógenos/metabolismo , Receptores de Progesterona/metabolismo , Neoplasias de la Mama/metabolismo , Supervivencia sin Enfermedad , Estudios Epidemiológicos , Femenino , Humanos , Análisis Multivariante , Metástasis de la Neoplasia , Pronóstico , Estudios Retrospectivos
2.
Med Sci Monit ; 24: 623-635, 2018 Jan 31.
Artículo en Inglés | MEDLINE | ID: mdl-29384143

RESUMEN

BACKGROUND Non-small cell lung carcinoma (NSCLC) mainly includes lung squamous cell carcinoma and adenocarcinoma. This study aimed to investigate the difference between the expression of Cbl-b in lung squamous cell carcinoma and adenocarcinoma. MATERIAL AND METHODS The clinical features and survival data of NSCLC patients and Cbl-b mRNA (FPKM) were obtained from the TCGA database. Then, lung squamous cell carcinoma and adenocarcinoma cell lines were transfected with lentivirus-mediated RNA interference vector to knockdown the expression of Cbl-b. Next, a Transwell assay was performed to study the effect of Cbl-b shRNA on migration and invasion of lung squamous cell carcinoma and adenocarcinoma cells. Finally, Western blot analysis was performed to measure the expressions of PI3K, p-PI3K, AKT, p-AKT, ERK1/2, p-ERK1/2, GSK3ß, p-GSK3ß, mTOR, and p-mTOR protein in lung adenocarcinoma and squamous cell carcinoma cells. RESULTS The correlation of Cbl-b expression and OS was different between NSCLC adenocarcinoma and squamous carcinoma. After transfection, the expression of Cbl-b was inhibited in A549, H1975, and SW900 cells. Cbl-b shRNA promoted the migration and invasion of lung adenocarcinoma A549 and H1975 cells, but it inhibited the invasion of lung squamous cell carcinoma SW900 cells. In addition, Cbl-b regulated the expression of PI3K and ERK1/2-GSK3ß pathway proteins in A549 and SW900 cells. CONCLUSIONS The OS of Cbl-b mRNA low expression in lung adenocarcinoma and squamous cell carcinoma was different. The difference in signal pathways may be one of the reasons for the difference in the correlation between Cbl-b expression and the survival rate of these 2 pathological types of lung cancer.


Asunto(s)
Proteínas Adaptadoras Transductoras de Señales/genética , Adenocarcinoma/genética , Carcinoma de Pulmón de Células no Pequeñas/genética , Neoplasias Pulmonares/genética , Proteínas Proto-Oncogénicas c-cbl/genética , Células A549 , Proteínas Adaptadoras Transductoras de Señales/metabolismo , Adenocarcinoma/patología , Adenocarcinoma del Pulmón , Carcinoma de Pulmón de Células no Pequeñas/patología , Movimiento Celular/genética , Quinasas MAP Reguladas por Señal Extracelular/metabolismo , Regulación Neoplásica de la Expresión Génica , Humanos , Neoplasias Pulmonares/patología , Invasividad Neoplásica , Fosfatidilinositol 3-Quinasas/metabolismo , Proteínas Proto-Oncogénicas c-cbl/metabolismo , ARN Mensajero/genética , ARN Mensajero/metabolismo , ARN Interferente Pequeño/metabolismo , Análisis de Supervivencia , Transfección
3.
BMC Cancer ; 17(1): 492, 2017 Jul 19.
Artículo en Inglés | MEDLINE | ID: mdl-28724364

RESUMEN

BACKGROUND: Although the efficacy of tamoxifen (TAM) for breast cancer has been attributed to inducing cell cycle arrest and apoptosis by inhibiting estrogen receptor (ER) signaling, recent evidence indicates that TAM also possesses ER-independent antitumor activity through an unclear mechanism. The present study investigated the anti-tumor mechanism of TAM on mesenchymal triple-negative breast cancer (TNBC). METHODS: The inhibitory effect of TAM on tumor migration and metastasis was analyzed by transwell chamber in vitro and by murine xenograft model in vivo. The promoter sequence of miR-200c was predicted by an online CpG island predictor. Relative expression of miR-200c was measured by quantitative real-time PCR. RESULTS: After treatment with TAM, mesenchymal TNBC cells (MCF-7/ADR and MDA-MB-231) morphologically changed from mesenchymal to epithelial types. Meanwhile, cell migration ability was also significantly decreased in ER-positive breast cancer cells after exposure to TAM. Consistent with these in-vitro results, TAM significantly suppressed lung metastasis rate of mesenchymal TNBC cells in murine xenograft tumors. miRNA array analysis of two types of breast cancer cells showed that miR-200c expression was inhibited in mesenchymal TNBC cells, but increased after TAM treatment due to demethylation of miR-200c promoters. CONCLUSIONS: Our results indicate that TAM inhibits cell migration and enhances chemosensitivity of mesenchymal TNBC cells by reversing their EMT-like property; and that this EMT-reversal effect results from upregulation of miR-200c through demethylating its promoter. To our knowledge, this is the first explanation of a non-ER-related mechanism for the effect of TAM on mesenchymal TNBC cells.


Asunto(s)
Transición Epitelial-Mesenquimal/efectos de los fármacos , MicroARNs/efectos de los fármacos , Tamoxifeno/farmacología , Neoplasias de la Mama Triple Negativas/tratamiento farmacológico , Animales , Antineoplásicos Hormonales , Línea Celular Tumoral , Movimiento Celular/efectos de los fármacos , Desmetilación del ADN , Femenino , Regulación Neoplásica de la Expresión Génica , Humanos , Neoplasias Pulmonares/tratamiento farmacológico , Neoplasias Pulmonares/secundario , Ratones , MicroARNs/química , MicroARNs/genética , MicroARNs/metabolismo , Regiones Promotoras Genéticas , Transducción de Señal , Tamoxifeno/uso terapéutico , Neoplasias de la Mama Triple Negativas/metabolismo , Neoplasias de la Mama Triple Negativas/patología , Ensayos Antitumor por Modelo de Xenoinjerto
4.
Lancet Oncol ; 16(4): 436-46, 2015 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-25795409

RESUMEN

BACKGROUND: Platinum chemotherapy has a role in the treatment of metastatic triple-negative breast cancer but its full potential has probably not yet been reached. We assessed whether a cisplatin plus gemcitabine regimen was non-inferior to or superior to paclitaxel plus gemcitabine as first-line therapy for patients with metastatic triple-negative breast cancer. METHODS: For this open-label, randomised, phase 3, hybrid-designed trial undertaken at 12 institutions or hospitals in China, we included Chinese patients aged 18-70 years with previously untreated, histologically confirmed metastatic triple-negative breast cancer, and an ECOG performance status of 0-1. These patients were randomly assigned (1:1) to receive either cisplatin plus gemcitabine (cisplatin 75 mg/m(2) on day 1 and gemcitabine 1250 mg/m(2) on days 1 and 8) or paclitaxel plus gemcitabine (paclitaxel 175 mg/m(2) on day 1 and gemcitabine 1250 mg/m(2) on days 1 and 8) given intravenously every 3 weeks for a maximum of eight cycles. Randomisation was done centrally via an interactive web response system using block randomisation with a size of eight, with no stratification factors. Patients and investigator were aware of group assignments. The primary endpoint was progression-free survival and analyses were based on all patients who received at least one dose of assigned treatment. The margin used to establish non-inferiority was 1·2. If non-inferiority of cisplatin plus gemcitabine compared with paclitaxel plus gemcitabine was achieved, we would then test for superiority. The trial is registered with ClinicalTrials.gov, number NCT01287624. FINDINGS: From Jan 14, 2011, to Nov 14, 2013, 240 patients were assessed for eligibility and randomly assigned to treatment (120 in the cisplatin plus gemcitabine group and 120 in the paclitaxel plus gemcitabine group). 236 patients received at least one dose of assigned chemotherapy and were included in the modified intention-to-treat analysis (118 per group). After a median follow-up of 16·3 months (IQR 14·4-26·8) in the cisplatin plus gemcitabine group and 15·9 months (10·7-25·4) in the paclitaxel plus gemcitabine group, the hazard ratio for progression-free survival was 0·692 (95% CI 0·523-0·915; pnon-inferiority<0·0001, psuperiority=0·009, thus cisplatin plus gemcitabine was both non-inferior to and superior to paclitaxel plus gemcitabine. Median progression-free survival was 7·73 months (95% CI 6·16-9·30) in the cisplatin plus gemcitabine group and 6·47 months (5·76-7·18) in the paclitaxel plus gemcitabine group. Grade 3 or 4 adverse events that differed significantly between the two groups included nausea (eight [7%] vs one [<1%]), vomiting (13 [11%] vs one [<1%]), musculoskeletal pain (none vs ten [8%]), anaemia (39 [33%] vs six [5%]), and thrombocytopenia (38 [32%] vs three [3%]), for the cisplatin plus gemcitabine compared with the paclitaxel plus gemcitabine groups, respectively. In addition, patients in the cisplatin plus gemcitabine group had significantly fewer events of grade 1-4 alopecia (12 [10%] vs 42 [36%]) and peripheral neuropathy (27 [23%] vs 60 [51%]), but more grade 1-4 anorexia (33 [28%] vs 10 [8%]), constipation (29 [25%] vs 11 [9%]), hypomagnesaemia (27 [23%] vs five [4%]), and hypokalaemia (10 [8%] vs two [2%]). Serious drug-related adverse events were seen in three patients in the paclitaxel plus gemcitabine group (interstitial pneumonia, anaphylaxis, and severe neutropenia) and four in the cisplatin plus gemcitabine group (pathological bone fracture, thrombocytopenia with subcutaneous haemorrhage, severe anaemia, and cardiogenic syncope). There were no treatment-related deaths. INTERPRETATION: Cisplatin plus gemcitabine could be an alternative or even the preferred first-line chemotherapy strategy for patients with metastatic triple-negative breast cancer. FUNDING: Shanghai Natural Science Foundation.


Asunto(s)
Protocolos de Quimioterapia Combinada Antineoplásica/administración & dosificación , Cisplatino/administración & dosificación , Desoxicitidina/análogos & derivados , Paclitaxel/administración & dosificación , Neoplasias de la Mama Triple Negativas/tratamiento farmacológico , Adulto , Protocolos de Quimioterapia Combinada Antineoplásica/efectos adversos , China , Cisplatino/efectos adversos , Desoxicitidina/administración & dosificación , Desoxicitidina/efectos adversos , Supervivencia sin Enfermedad , Femenino , Humanos , Persona de Mediana Edad , Estadificación de Neoplasias , Paclitaxel/efectos adversos , Resultado del Tratamiento , Neoplasias de la Mama Triple Negativas/patología , Gemcitabina
5.
BMC Cancer ; 15: 50, 2015 Feb 13.
Artículo en Inglés | MEDLINE | ID: mdl-25885449

RESUMEN

BACKGROUND: Drug resistance is a major challenge in cancer therapeutics. Abundant evidence indicates that DNA repair systems are enhanced after repetitive chemotherapeutic treatments, rendering cancers cells drug-resistant. Flap endonuclease 1 (FEN1) plays critical roles in DNA replication and repair and in counteracting replication stress, which is a key mechanism for many chemotherapeutic drugs to kill cancer cells. FEN1 was previously shown to be upregulated in response to DNA damaging agents. However, it is unclear about the transcription factors that regulate FEN1 expression in human cancer. More importantly, it is unknown whether up-regulation of FEN1 has an adverse impact on the prognosis of chemotherapeutic treatments of human cancers. METHODS: To reveal regulation mechanism of FEN1 expression, we search and identify FEN1 transcription factors or repressors and investigate their function on FEN1 expression by using a combination of biochemical, molecular, and cellular approaches. Furthermore, to gain insights into the impact of FEN1 levels on the response of human cancer to therapeutic treatments, we determine FEN1 levels in human breast cancer specimens and correlate them to the response to treatments and the survivorship of corresponding breast cancer patients. RESULTS: We observe that FEN1 is significantly up-regulated upon treatment of chemotherapeutic drugs such as mitomycin C (MMC) and Taxol in breast cancer cells. We identify that the transcription factor/repressor YY1 binds to the FEN1 promoter and suppresses the expression of FEN1 gene. In response to the drug treatments, YY1 is dissociated from the FEN1 promoter region leading over-expression of FEN1. Overexpression of YY1 in the cells results in down-regulation of FEN1 and sensitization of the cancer cells to MMC or taxol. Furthermore, we observe that the level of FEN1 is inversely correlated with cancer drug and radiation resistance and with survivorship in breast cancer patients. CONCLUSION: Altogether, our current data indicate that YY1 is a transcription repressor of FEN1 regulating FEN1 levels in response to DNA damaging agents. FEN1 is up-regulated in human breast cancer and its levels inversely correlated with cancer drug and radiation resistance and with survivorship in breast cancer patients.


Asunto(s)
Neoplasias de la Mama/genética , Neoplasias de la Mama/metabolismo , Resistencia a Antineoplásicos/genética , Endonucleasas de ADN Solapado/genética , Regulación Neoplásica de la Expresión Génica , Factor de Transcripción YY1/metabolismo , Antineoplásicos/farmacología , Secuencia de Bases , Sitios de Unión , Neoplasias de la Mama/mortalidad , Línea Celular , Secuencia Conservada , Femenino , Humanos , Estimación de Kaplan-Meier , Motivos de Nucleótidos , Pronóstico , Regiones Promotoras Genéticas , Unión Proteica
6.
J BUON ; 20(3): 800-7, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-26214633

RESUMEN

PURPOSE: Several clinical trials have suggested that adjuvant chemotherapy improves the survival of patients with resected gastric cancer, but the optimal time at which to initiate post-operative adjuvant chemotherapy has not been studied. This study investigated the association between time to adjuvant chemotherapy and survival in gastric cancer. METHODS: We retrospectively identified 266 patients with stage IB-IIIC gastric cancer who received fluorouracil-based adjuvant chemotherapy after radical gastrectomy. Overall survival (OS) was compared between patients grouped according to time from surgery to adjuvant chemotherapy (<45 and ≥45 days). The Cox proportional hazards model was used to analyze the effects of time to initiation of chemotherapy and other clinical covariates on survival. RESULTS: Of 266 patients, 141 (53%) started adjuvant chemotherapy within 45 days after surgery and 125 (47%) started adjuvant chemotherapy more than 45 days after surgery. The 3-year OS rates were 81.2 and 65.8% for patients starting chemotherapy within 45 days and after 45 days, respectively (p=0.006). Multivariate analysis identified early initiation of adjuvant chemotherapy, completion of the planned chemotherapy, and early-stage disease as favorable prognostic factors in terms of OS (p<0.05). Subgroup analysis suggested that starting chemotherapy within 45 days after surgery was associated with significant OS benefit compared with initiation of chemotherapy after 45 days from surgery in most subgroups. CONCLUSIONS: This retrospective analysis suggests that delaying adjuvant chemotherapy for longer than 45 days after surgery may be associated with poorer survival in patients with resected gastric cancer.


Asunto(s)
Antimetabolitos Antineoplásicos/administración & dosificación , Fluorouracilo/administración & dosificación , Gastrectomía , Neoplasias Gástricas/terapia , Adulto , Anciano , Antimetabolitos Antineoplásicos/efectos adversos , Quimioterapia Adyuvante , Distribución de Chi-Cuadrado , Esquema de Medicación , Femenino , Fluorouracilo/efectos adversos , Gastrectomía/efectos adversos , Gastrectomía/mortalidad , Humanos , Estimación de Kaplan-Meier , Masculino , Persona de Mediana Edad , Análisis Multivariante , Estadificación de Neoplasias , Modelos de Riesgos Proporcionales , Estudios Retrospectivos , Factores de Riesgo , Neoplasias Gástricas/mortalidad , Neoplasias Gástricas/patología , Factores de Tiempo , Resultado del Tratamiento
7.
Front Oncol ; 13: 978985, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-36761968

RESUMEN

Objective: This study aimed to explore possible associations between molecular subtypes and site of distant metastasis in advanced breast cancer (ABC). Methods: 3577 ABC patients were selected from 21 hospitals of seven geographic regions in China from 2012-2014. A questionnaire was designed to collect medical information regarding demographic characteristics, risk factors, molecular subtype, recurrence/metastasis information, and disease-free survival (DFS). The cancers were classified into Luminal A, Luminal B, HER2-enriched and Triple Negative subtypes. Chi-square test and multivariate Cox proportional hazard models were performed to explore the associations between molecular subtypes and distant metastasis sites. Results: A total of 2393 cases with molecular subtypes information were finally examined. Patients with Luminal A (51.1%) and Luminal B (44.7%) were most prone to bone metastasis, whereas liver metastasis was more frequently observed in HER2-enriched ABC patients (29.1%).The cumulative recurrence and metastasis rates of ABC patients at 36 months of DFS were the most significant within molecular types, of which Triple Negative was the highest (82.7%), while that of Luminal A was the lowest (58.4%). In the adjusted Cox regression analysis, Luminal B, HER2-enriched and Triple Negative subtypes increased the risk of visceral metastasis by 23%, 46% and 87% respectively. In addition, Triple Negative patients had a higher probability of brain metastasis (HR 3.07, 95% CI: 1.04-9.07). Conclusion: Molecular subtypes can predict the preferential sites of distant metastasis, emphasizing that these associations were of great help in choices for surveillance, developing appropriate screening and cancer management strategies for follow-up and personalized therapy in ABC patients.

8.
Nat Commun ; 13(1): 4025, 2022 07 12.
Artículo en Inglés | MEDLINE | ID: mdl-35821019

RESUMEN

Platinum is recommended in combination with gemcitabine in the treatment of metastatic triple-negative breast cancer (mTNBC). We conduct a randomized phase 3, controlled, open-label trial to compare nab-paclitaxel/cisplatin (AP) with gemcitabine/cisplatin (GP) in mTNBC patients (ClinicalTrials.gov NCT02546934). 254 patients with untreated mTNBC randomly receive AP (nab-paclitaxel 125 mg/m² on day 1, 8 and cisplatin 75 mg/m² on day 1) or GP (gemcitabine 1250 mg/m² on day 1, 8 and cisplatin 75 mg/m² on day 1) intravenously every 3 weeks until progression disease, intolerable toxicity or withdrawal of consent. The primary endpoint is progression-free survival (PFS); secondary endpoints are objective response rate (ORR), safety and overall survival (OS). The trial has met pre-specified endpoints. The median PFS is 9.8 months with AP as compared to 7.4 months with GP (stratified HR, 0.67; 95% CI, 0.50-0.88; P = 0.004). AP significantly increases ORR (81.1% vs. 56.3%, P < 0.001) and prolongs OS (stratified HR, 0.62; 95% CI, 0.44-0.90; P = 0.010) to GP. Of grade 3 or 4 adverse events, a significantly higher incidence of neuropathy in AP and thrombocytopenia in GP is noted. These findings warrant further assessment of adding novel agents to the nab-paclitaxel/platinum backbone due to its high potency for patients with mTNBC.


Asunto(s)
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Neoplasias de la Mama Triple Negativas , Albúminas/administración & dosificación , Cisplatino/administración & dosificación , Desoxicitidina/administración & dosificación , Desoxicitidina/análogos & derivados , Humanos , Metástasis de la Neoplasia , Paclitaxel/administración & dosificación , Neoplasias de la Mama Triple Negativas/tratamiento farmacológico , Neoplasias de la Mama Triple Negativas/patología , Gemcitabina
9.
Ann Transl Med ; 10(15): 813, 2022 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-36034985

RESUMEN

Background: Several studies have indicated possible associations between age and the prognosis of breast cancer (BC), but limited data are available from hospital-based multicenter studies in China. This study aimed to explore the associations between age at initial diagnosis of BC and the risk of recurrence or metastasis among Chinese women with newly diagnosed advanced breast cancer (ABC) and provide treatment decision support for BC patients of different ages to medical workers. Methods: The medical records of patients newly diagnosed with ABC were obtained from 21 hospitals in seven geographic regions in China from 2012 to 2014. Patients' general information, clinicopathological features at first diagnosis, treatment information, and prognosis were retrospectively collected based on the self-designed case report form (CRF). Cox proportional hazards regression models were used to determine hazard ratios (HR) and 95% confidence intervals (CI) for the associations between age groups and the risk of recurrence and metastasis. Results: A total of 1,852 cases were included in the final analysis. Age at initial diagnosis was shown to be significantly related to hormone receptor status, human epidermal growth factor receptor 2 (HER2) status, molecular subtypes, and the number of lymph node metastasis (all P<0.05). Patients aged <35 years were more likely to have bone metastasis (45.6%). Patients aged ≥65 years had a lower percentage of receiving surgery (87.1%), adjuvant chemotherapy (61.3%), adjuvant radiotherapy (35.5%), and adjuvant endocrine therapy (30.6%) than the other groups (all P<0.05). Compared with patients aged <35 years, the risk of recurrence or metastasis in those aged 55-64 years was significantly higher (HRage 55-64 =1.24, 95% CI: 1.04-1.47), and the risk of bone metastasis and lung metastasis in those aged 35-44 years was lower (HRbone metastasis =0.74, 95% CI: 0.59-0.93; HRlung metastasis =0.70, 95% CI: 0.53-0.93). After adjusting for stage, grade, and molecular subtype, surgery, neoadjuvant chemotherapy, adjuvant chemotherapy, adjuvant radiotherapy, adjuvant endocrine therapy, and family history of BC, patients aged 35-44 years still had a significantly reduced risk of bone metastasis and lung metastasis by 31% and 52%, respectively (HRbone metastasis =0.69, 95% CI: 0.48-0.98; HRlung metastasis =0.48, 95% CI: 0.31-0.74). Conclusions: Age at initial diagnosis is related to the clinicopathological characteristics and treatment pattern. Although the risk of site-specific metastasis varies by age, age is not an independent factor influencing the risk of total recurrence and metastasis. In accordance with current clinical practice guidelines for BC, however, precise treatment shall be chosen personally for patients whose ages at initial diagnosis are different.

10.
Acta Oncol ; 50(5): 693-9, 2011 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-21175263

RESUMEN

BACKGROUND: Tamoxifen (TAM) is a nonsteroidal antiestrogen that has been widely used in the treatment of breast cancer through its anti-estrogen activity. Recent studies show that TAM is cytotoxic to both estrogen receptor (ER)-positive and ER-negative cells via the induction of apoptosis. However, the molecular mechanisms of this effect are not well understood. In the present study, we investigated the roles of c-Src, ERK, AKT and c-Cbl ubiquitin ligases during TAM-induced apoptosis of MCF-7 cells. MATERIAL AND METHODS: MCF-7 cell proliferation and apoptosis were measured by 3-(4,5-dimethyl thiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, and flow cytometry, respectively. c-Cbl expression, and the activity of c-Src, ERK, AKT were assayed by Western blotting. Overexpression of the wild and the dominant-negative type of c-Cbl (70Z/Cbl) were achieved by transient transfection of plasmids encoding c-Cbl and 70Z/Cbl, respectively, and were confirmed by Western blotting. Statistical analysis was performed using the t-test, and a p-value <0.05 was considered to be statistically significant. RESULTS: A high concentration of TAM (25 µM) induced a time-dependent apoptosis of MCF-7 cells. ERK1/2 and AKT were activated during TAM-induced apoptosis. The ERK1/2 inhibitor PD98059, the PI3K/Akt inhibitor LY294002, and the c-Src inhibitor PP2 all enhanced TAM action. Moreover, the ubiquitin ligase c-Cbl was up-regulated during this process. Over-expression of c-Cbl significantly enhanced the apoptosis-inducing effects of TAM, while 70Z/Cbl suppressed the apoptosis-inducing effects of TAM. Further investigation revealed that, overexpression of c-Cbl significantly downregulated the c-Src protein levels and TAM-induced AKT activity. But 70Z/Cbl significantly upregulated TAM-induced ERK and AKT activity. CONCLUSIONS: This study demonstrates that c-Src, ERK, and AKT played a protective role during TAM-induced apoptosis, and that c-Cbl sensitized MCF-7 cells to TAM by modulating the expression of c-Src, and TAM-induced ERK and AKT activity.


Asunto(s)
Apoptosis/efectos de los fármacos , Neoplasias de la Mama/patología , Carcinoma/patología , Proteínas Proto-Oncogénicas c-cbl/fisiología , Tamoxifeno/farmacología , Apoptosis/genética , Neoplasias de la Mama/metabolismo , Carcinoma/metabolismo , Línea Celular Tumoral , Supervivencia Celular/efectos de los fármacos , Supervivencia Celular/genética , Regulación hacia Abajo/efectos de los fármacos , Regulación hacia Abajo/genética , Resistencia a Antineoplásicos/efectos de los fármacos , Resistencia a Antineoplásicos/genética , Antagonistas de Estrógenos/farmacología , Quinasas MAP Reguladas por Señal Extracelular/metabolismo , Femenino , Humanos , Proteínas Proto-Oncogénicas c-akt/metabolismo , Proteínas Proto-Oncogénicas c-cbl/genética , Transducción de Señal/efectos de los fármacos , Transducción de Señal/genética , Ubiquitina-Proteína Ligasas/genética , Ubiquitina-Proteína Ligasas/fisiología
11.
BioDrugs ; 35(3): 337-350, 2021 May.
Artículo en Inglés | MEDLINE | ID: mdl-33826080

RESUMEN

BACKGROUND: HLX02 is an approved biosimilar of trastuzumab. OBJECTIVE: This study aimed to evaluated the efficacy, safety, and immunogenicity of HLX02 compared with reference trastuzumab in patients with human epidermal growth factor receptor 2 (HER2)-positive recurrent or metastatic breast cancer. PATIENTS AND METHODS: This randomized, double-blind, phase III study was conducted at 89 centers in China, the Philippines, Poland, and Ukraine. Eligible patients were randomized (1:1) to receive HLX02 or European Union (EU)-sourced trastuzumab (initial dose of 8 mg/kg, followed by 6 mg/kg every 3 weeks for up to 12 months) in combination with docetaxel intravenously. The primary endpoint was overall response rate up to week 24 (ORR24). Equivalence was declared if the 95% confidence interval (CI) of difference was within ± 13.5%. Safety and immunogenicity were evaluated in patients who received at least one dose of study medication. RESULTS: Between 11 November 2016 and 10 July 2019, a total of 649 patients were enrolled. The ORR24 was 71.3 and 71.4% in the HLX02 (n = 324) and EU-trastuzumab (n = 325) groups, with a difference of - 0.1% (95% CI - 7 to 6.9), which fell entirely in the predefined equivalence margins. No statistically significant differences were observed in all secondary efficacy analyses. Safety profiles and immunogenicity were comparable in HLX02 and EU-trastuzumab groups. In total, 98.8% of patients in each group experienced at least one treatment-emergent adverse event (TEAE), 23.8 and 24.9% experienced serious TEAEs, and 0.6% in each group had antidrug antibodies. CONCLUSIONS: Among patients with HER2-positive recurrent or metastatic breast cancer, HLX02 demonstrated equivalent efficacy and similar safety and immunogenicity to reference trastuzumab. CLINICAL TRIAL REGISTRATION: Chinadrugtrials.org CTR20160526 (12 September 2016), ClinicalTrials.gov NCT03084237 (20 March 2017), EudraCT 2016-000206-10 (27 April 2017).


Trastuzumab is a biologic drug used to treat patients with certain types of breast cancer and stomach cancer. Biosimilars are medications that are almost identical to and indistinguishable from original biologic drugs but usually less expensive and more accessible. The main purpose of this study was to evaluate the efficacy (treatment effects) of HLX02 (trastuzumab biosimilar) compared with reference trastuzumab in patients with human epidermal growth factor receptor 2 (HER2)-positive recurrent or metastatic breast cancer. Other objectives were to evaluate the safety of HLX02 by monitoring adverse events and assessing its potential to induce antibody production (which can prevent a drug from being effective). Patients with HER2-positive recurrent or metastatic breast cancer were randomly allocated to receive HLX02 (n = 324) or European Union (EU)-sourced trastuzumab (n = 325). Study drugs (HLX02 or EU-trastuzumab) were given intravenously, with an initial dose of 8 mg/kg, followed by 6 mg/kg every 3 weeks for up to 12 months. Statistical analyses showed that HLX02 was equivalent to trastuzumab in efficacy evaluations. Adverse events observed in the HLX02 treatment group were consistent with those seen with trastuzumab in the current and previous clinical studies. Additionally, no statistically significant differences were seen in the tendency to stimulate antibody production between the two study drugs. To conclude, HLX02 and reference trastuzumab had similar efficacy and safety profiles. These data support the approval of HLX02 as a trastuzumab biosimilar.


Asunto(s)
Neoplasias de la Mama , Protocolos de Quimioterapia Combinada Antineoplásica/efectos adversos , Neoplasias de la Mama/tratamiento farmacológico , Docetaxel/uso terapéutico , Humanos , Polonia , Receptor ErbB-2 , Trastuzumab/efectos adversos
12.
Ann Transl Med ; 9(3): 258, 2021 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-33708885

RESUMEN

BACKGROUND: Tamoxifen is an important choice in endocrine therapy for patients with oestrogen receptor-positive (ER+) breast cancer, and disease progression-associated resistance to tamoxifen therapy is still challenging. Flap endonuclease-1 (FEN1) is used as a prognostic biomarker and is considered to participate in proliferation, migration, and drug resistance in multiple cancers, especially breast cancer, but the prognostic function of FEN1 in ER+ breast cancer, and whether FEN1 is related to tamoxifen resistance or not, remain to be explored. METHODS: On-line database Kaplan-Meier (KM) plotter, GEO datasets, and immunohistochemistry were used to analyse the prognostic value of FEN1 in ER+ breast cancer from mRNA and protein levels. Cell viability assay and colony formation assays showed the response of tamoxifen in MCF-7 and T47D cells. Microarray data with FEN1 siRNA versus control group in MCF-7 cells were analysed by Gene Set Enrichment Analysis (GSEA). The protein levels downstream of FEN1 were detected by western blot assay. RESULTS: ER+ breast cancer patients who received tamoxifen for adjuvant endocrine therapy with poor prognosis showed a high expression of FEN1. MCF-7 and T47D appeared resistant to tamoxifen after FEN1 over-expression and increased sensitivity to tamoxifen after FEN1 knockdown. Importantly, FEN1 over-expression could activate tamoxifen resistance through the ERα/cyclin D1/Rb axis. CONCLUSIONS: As a biomarker of tamoxifen effectiveness, FEN1 participates in tamoxifen resistance through ERα/cyclin D1/Rb axis. In the future, reversing tamoxifen resistance by knocking-down FEN1 or by way of action as a small molecular inhibitor of FEN1 warrants further investigation.

13.
J Oncol ; 2021: 6621722, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34567118

RESUMEN

OBJECTIVE: To better understand the status of medical treatment for human epidermal growth factor receptor 2 (HER2)-positive breast cancer and the differences between the Chinese and the international clinical practice. METHODS: This was a retrospective, nationwide, multicenter, epidemiological study of advanced breast cancer patients from China. Between January 01, 2012, and December 31, 2014, a total of 3649 patients, covering 7 geographic regions and 21 institutions, participated in this series of studies. HER2-positive breast cancer was selected among the group and adopted into this study. In comparison, we summarized the demographics and clinical characteristics of HER2-positive breast cancer from the Surveillance, Epidemiology, and End Results (SEER) database. RESULTS: A total of 918 patients diagnosed as HER2-positive breast cancer patients were included. The median age at diagnosis was 46 years (ranging, 23 to 78) with a single-peak incidence. The proportions of stages II-IV at diagnosis and distance metastasis in viscera were more than half of the participants. In comparison, the prevalence of estrogen or progesterone receptor-positive expression and luminalB subtype was relatively lower than that of the United States. The receipt of chemotherapy was fairly higher, while the usage of targeted therapy was seriously insufficient. Tumor size was in significantly positive associations with the duration of targeted therapy (Kendall's correlation coefficient = 0.3, P < 0.0001), while no prohibitive variables among clinical characteristics were detected. CONCLUSION: Our study suggested that HER2-positive breast cancer patients were characterized as a younger trend, a lower prevalence of hormonal receptor (HR)-positive expression, and less accessible to anti-HER2 targeted therapy with insufficient duration over the past few years in China. Concerted efforts should be exerted for promising survival benefits in the future. The trial registration number is https://clinicaltrials.gov/ct2/show/NCT03047889.

14.
Oncol Res Treat ; 43(11): 620-627, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32966998

RESUMEN

PURPOSE: At the first time of metastatic breast cancer recurrence, conversion of the receptors status may occur between primary lesions and metastatic lesions, including the estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2). Whether the decision of the treatment regimen is based on the primary receptor status or that of metastatic lesions is still unclear. METHODS: This study enrolled 411 female patients with a diagnosis of metastatic breast cancer at the first time of recurrence to explore the influence of receptor conversion on prognosis prediction and treatment regimen of patients with metastatic breast cancer. RESULTS: ER and PR changes from negative to positive are both prognostic factors for patients with breast cancer. Patients receiving endocrine therapy showed a better survival after recurrence than those using chemotherapy alone in the ER or PR Prim- Met+ subgroup. Patients in the HER2 Prim- Met+ subgroup using HER2-targeted therapy in multilines showed a post-recurrence survival advantage. In the bone re-biopsy subgroup, the PR change from positive to negative appeared to be more frequent than at other re-biopsy sites. CONCLUSIONS: Patients with metastatic breast cancer should perform re-biopsy to clarify the receptor status of the first metastatic lesions, which may provide clinicians valuable evidence to conduct treatments with higher precision.


Asunto(s)
Neoplasias de la Mama/mortalidad , Neoplasias de la Mama/patología , Receptor ErbB-2/metabolismo , Receptores de Estrógenos/metabolismo , Receptores de Progesterona/metabolismo , Adulto , Anciano , Biomarcadores de Tumor , Biopsia , Neoplasias de la Mama/terapia , Supervivencia sin Enfermedad , Femenino , Humanos , Inmunohistoquímica , Estimación de Kaplan-Meier , Persona de Mediana Edad , Metástasis de la Neoplasia , Recurrencia Local de Neoplasia , Pronóstico , Tasa de Supervivencia
15.
Oncol Rep ; 44(6): 2443-2454, 2020 12.
Artículo en Inglés | MEDLINE | ID: mdl-33125141

RESUMEN

Flap endonuclease­1 (FEN1), a structure­specific nuclease participating in DNA replication and repair processes, has been confirmed to promote the proliferation and drug resistance of tumor cells. However, the biological functions of FEN1 in cancer cell migration and invasion have not been defined. In the present study, using online database analysis and immunohistochemistry of the specimens, it was found that FEN1 expression was associated with a highly invasive triple­negative breast cancer (TNBC) subtype in both breast cancer samples from the Oncomine database and from patients recruited into the study. Furthermore, FEN1 was an important biomarker of lymph node metastasis and poor prognosis in patients with TNBC. FEN1 promoted migration of TNBC cell lines and FEN1 knockdown reduced the number of spontaneous lung metastasis in vivo. Ingenuity Pathway Analysis of FEN1­related transcripts in 198 patients with TNBC demonstrated that the polo­like kinase family may be the downstream target of FEN1. PLK4 was further identified as a critical target of FEN1 mediating TNBC cell migration, by regulating actin cytoskeleton rearrangement. The results of the present study validate FEN1 as a therapeutic target in patients with TNBC and revealed a new role for FEN1 in regulating TNBC invasion and metastasis.


Asunto(s)
Biomarcadores de Tumor/metabolismo , Endonucleasas de ADN Solapado/metabolismo , Neoplasias Pulmonares/secundario , Recurrencia Local de Neoplasia/epidemiología , Neoplasias de la Mama Triple Negativas/patología , Animales , Biomarcadores de Tumor/análisis , Biomarcadores de Tumor/genética , Mama/patología , Mama/cirugía , Línea Celular Tumoral , Proliferación Celular , Supervivencia sin Enfermedad , Femenino , Endonucleasas de ADN Solapado/análisis , Endonucleasas de ADN Solapado/genética , Estudios de Seguimiento , Técnicas de Silenciamiento del Gen , Humanos , Metástasis Linfática/patología , Mastectomía , Ratones , Persona de Mediana Edad , Recurrencia Local de Neoplasia/patología , Estadificación de Neoplasias , Pronóstico , RNA-Seq , Análisis de Matrices Tisulares , Neoplasias de la Mama Triple Negativas/diagnóstico , Neoplasias de la Mama Triple Negativas/mortalidad , Neoplasias de la Mama Triple Negativas/cirugía , Ensayos Antitumor por Modelo de Xenoinjerto
16.
Front Oncol ; 10: 425, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32318339

RESUMEN

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer, which is very difficult to treat and commonly develops resistance to chemotherapy. The following study investigated whether the inhibition of Flap Endonuclease 1 (FEN1) expression, the key enzyme in the base excision repair (BER) pathway, could improve the anti-tumor effect of arsenic trioxide (ATO), which is a reactive oxygen species (ROS) inducer. Our data showed that ATO could increase the expression of FEN1, and the knockdown of FEN1 could significantly enhance the sensitivity of TNBC cells to ATO both in vitro and in vivo. Further mechanism studies revealed that silencing FEN1 in combination with low doses of ATO might increase intracellular ROS and reduce glutathione (GSH) levels, by reducing the nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2); elevating ROS leaded to apoptosis and p38 and JNK pathway activating. In conclusion, our study suggested the combination of FEN1 knockdown and ATO could induce TNBC cell death by promoting ROS production. FEN1 knockdown can effectively decrease the application concentrations of ATO, thus providing a possibility for the treatment of TNBC with ATO.

17.
Acta Oncol ; 48(8): 1173-80, 2009.
Artículo en Inglés | MEDLINE | ID: mdl-19863226

RESUMEN

BACKGROUND. Exosomes are nanometer-sized vesicles with immunomodulatory functions, which are released by a diverse range of living cells. Although recent studies have shown that tumor-derived exosomes can suppress the function of T cells, the molecular mechanisms are not well understood. In the present study, we investigated the role of the Casitas B lineage lymphoma (cbl) family of ubiquitin ligases in gastric cancer exosome-induced apoptosis of Jurkat T cells. MATERIALS AND METHODS. By serial centrifugation and sucrose gradient ultracentrifugation, we isolated and purified the exosomes from gastric cancer SGC7901 cells, and identified them by electron microscopy and Western blotting. Cell apoptosis was detected using propidium iodide staining. Western blotting and RT-PCR was exploited to evaluate the expression of proteins and mRNA, respectively. RESULTS. Gastric cancer exosomes induced Jurkat T cell apoptosis in a time- and dose-dependent manner and activated caspases 3, 8 and 9. The expression of Cbl-b and c-Cbl was up-regulated during exosome-induced apoptosis of cells. Meanwhile, exosomes induced ubiquitination of the p85 subunit of phosphoinositide 3-kinase (PI3K) and reduced downstream Akt activity. Inhibition of proteasome led to partial restoration of Akt activity and cell apoptosis. DISCUSSION AND CONCLUSIONS. The Cbl family of ubiquitin ligases might be involved in regulation of exosome-induced apoptosis of Jurkat T cells by increasing PI3K proteasome degradation, inactivation of PI3K/Akt signaling, thus mediating some effects of caspase activation.


Asunto(s)
Apoptosis/fisiología , Caspasas/metabolismo , Exosomas/metabolismo , Complejo de la Endopetidasa Proteasomal/metabolismo , Proteínas Proto-Oncogénicas c-cbl/fisiología , Neoplasias Gástricas/enzimología , Neoplasias Gástricas/inmunología , Linfocitos T/fisiología , Ubiquitina-Proteína Ligasas/fisiología , Adenocarcinoma , Western Blotting , Caspasa 3/metabolismo , Caspasa 8/metabolismo , Caspasa 9/metabolismo , Línea Celular Tumoral , Regulación Neoplásica de la Expresión Génica , Humanos , Células Jurkat , Fosfatidilinositol 3-Quinasas/metabolismo , Proteínas Proto-Oncogénicas c-akt/metabolismo , Proteínas Proto-Oncogénicas c-cbl/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Transducción de Señal , Neoplasias Gástricas/ultraestructura , Ubiquitina-Proteína Ligasas/metabolismo , Regulación hacia Arriba
18.
J Thorac Dis ; 10(3): 1635-1647, 2018 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-29707316

RESUMEN

BACKGROUND: Casitas B-lineage lymphoma proto-oncogene-b (CBLB) influences the threshold of T cell activation and controlling peripheral T cell tolerance. In the present study, we hypothesize that potentially functional single nucleotide polymorphisms (SNPs) in CBLB are associated with clinical outcomes in patients advanced non-small cell lung cancer (NSCLC) treated with the first-line chemotherapy. METHODS: We genotyped three SNPs (rs2305035, rs3772534 and rs9657904) at CBLB in 116 advanced NSCLC patients with progression free survival (PFS) data and 133 advanced NSCLC patients with overall survival (OS) data, and we assessed their associations, 95% confidence interval (CI), with clinical outcomes by using Cox proportional hazards regression analyses. In silico functional analysis was also performed for the SNPs under investigation. RESULTS: We found that associations between the three SNPs and PFS/OS were not significant in the overall NSCLC patients. The rs2305035 AA genotype was associated with a worse PFS in female patients and those of non-smokers or light smokers (95% CI, 1.14-11.81, P=0.030; 95% CI, 1.42-10.24, P=0.008; and 95% CI, 1.39-9.93, P=0.009; respectively), compared with the GG+AA genotypes. We also found that the rs9657904 CC genotype was significantly associated with a worse OS than TT + TC genotypes in male advanced NSCLC patients. Further in silico functional analysis revealed that the rs965704 T allele was significantly associated with lower mRNA expression levels of the CBLB gene. CONCLUSIONS: Our findings identified two CBLB SNPs (rs2305035 and rs9657904) that were significantly associated with PFS and OS in several subgroups of Chinese advanced NSCLC patients after the first-line chemotherapy.

19.
PLoS One ; 10(6): e0128540, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-26075713

RESUMEN

Prognostic models are generally used to predict gastric cancer outcomes. However, no model combining patient-, tumor- and host-related factors has been established to predict outcomes after radical gastrectomy, especially outcomes of patients without nodal involvement. The aim of this study was to develop a prognostic model based on the systemic inflammatory response and clinicopathological factors of resectable gastric cancer and determine whether the model can improve prognostic accuracy in node-negative patients. We reviewed the clinical, laboratory, histopathological and survival data of 1397 patients who underwent radical gastrectomy between 2007 and 2013. Patients were split into development and validation sets of 1123 and 274 patients, respectively. Among all 1397 patients, 545 had node-negative gastric cancer; 440 were included in the development set, 105 were included in the validation set. A prognostic model was constructed from the development set. The scoring system was based on hazard ratios in a Cox proportional hazard model. In the multivariate analysis, age, tumor size, Lauren type, depth of invasion, lymph node metastasis, and the neutrophil--lymphocyte ratio were independent prognostic indicators of overall survival. A prognostic model was then established based on the significant factors. Patients were categorized into five groups according to their scores. The 3-year survival rates for the low- to high-risk groups were 98.9%, 92.8%, 82.4%, 58.4%, and 36.9%, respectively (P < 0.001). The prognostic model clearly discriminated patients with stage pT1-4N0M0 tumor into four risk groups with significant differences in the 3-year survival rates (P < 0.001). Compared with the pathological T stage, the model improved the predictive accuracy of the 3-year survival rate by 5% for node-negative patients. The prognostic scores also stratified the patients with stage pT4aN0M0 tumor into significantly different risk groups (P = 0.004). Furthermore, the predictive value of this model was validated in an independent set of 274 patients. This model, which included the systemic inflammatory markers and clinicopathological factors, is more effective in predicting the prognosis of node-negative gastric cancer than traditional staging systems. Patients in the high-risk group might be good candidates for adjuvant chemotherapy.


Asunto(s)
Neoplasias Gástricas/epidemiología , Neoplasias Gástricas/patología , Adulto , Anciano , Anciano de 80 o más Años , Biomarcadores , Femenino , Estudios de Seguimiento , Gastrectomía , Humanos , Estimación de Kaplan-Meier , Metástasis Linfática , Masculino , Persona de Mediana Edad , Clasificación del Tumor , Estadificación de Neoplasias , Evaluación de Resultado en la Atención de Salud , Pronóstico , Curva ROC , Reproducibilidad de los Resultados , Estudios Retrospectivos , Neoplasias Gástricas/mortalidad , Neoplasias Gástricas/cirugía , Síndrome de Respuesta Inflamatoria Sistémica/epidemiología , Síndrome de Respuesta Inflamatoria Sistémica/mortalidad , Carga Tumoral
20.
Zhonghua Yi Xue Za Zhi ; 83(23): 2058-60, 2003 Dec 10.
Artículo en Zh | MEDLINE | ID: mdl-14703416

RESUMEN

OBJECTIVE: To compare the efficacy and safety of ramosetron and granisetron in prevention of gastrointestinal reaction induced by cisplatin or adramycin. METHODS: Fifty chemotherapy-naive patients with histological confirmed malignancies were randomized divided into 2 groups: AB group (ramosetron 0.3 mg was given in first cycle and granisetron 3mg in the second cycle) and BA group (these drugs were given in the reverse sequence). The appetite, side effects, such as nausea, vomiting, headache, dizziness, etc. were observed. RESULTS: A total of 47 patients, 27 receiving cisplatin and 20 receiving adramycin, were evaluable. 0-24 hours after the treatment, the inhibition rate of anorexia was 72.3% in the ramosetron group, significantly lower than that in the granisetron group (51.1%, P < 0.05). The inhibition rate of nausea was 66.0% in the ramosetron group, significantly lower than that in the granisetron group (44.6%, P < 0.05), and the inhibition rate of vomiting was 76.6% in the ramosetron group, not significantly different from that in the granisetron group (70.2%). The incidence rate of adverse events was similar in these two groups. The most common adverse event was headache. CONCLUSION: Ramosetron is a safe and effective antiemetic and is more cost-effective than granisetron.


Asunto(s)
Antineoplásicos/efectos adversos , Apetito/efectos de los fármacos , Bencimidazoles/uso terapéutico , Granisetrón/uso terapéutico , Náusea/prevención & control , Vómitos/prevención & control , Adolescente , Adulto , Anciano , Cisplatino/efectos adversos , Doxorrubicina/efectos adversos , Femenino , Humanos , Masculino , Persona de Mediana Edad
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA