Copy number signatures and CCNE1 amplification reveal the involvement of replication stress in high-grade endometrial tumors oncogenesis.

PURPOSE: Managing high-grade endometrial cancer in Martinique poses significant challenges. The diversity of copy number alterations in high-grade endometrial tumors, often associated with a TP53 mutation, is a key factor complicating treatment. Due to the high incidence of high-grade tumors with poor prognosis, our study aimed to characterize the molecular signature of these tumors within a cohort of 25 high-grade endometrial cases. METHODS: We conducted a comprehensive pangenomic analysis to categorize the copy number alterations involved in these tumors. Whole-Exome Sequencing (WES) and Homologous Recombination (HR) analysis were performed. The alterations obtained from the WES were classified into various signatures using the Copy Number Signatures tool available in COSMIC. RESULTS: We identified several signatures that correlated with tumor stage and disctinct prognoses. These signatures all seem to be linked to replication stress, with CCNE1 amplification identified as the primary driver of oncogenesis in over 70% of tumors analyzed. CONCLUSION: The identification of CCNE1 amplification, which is currently being explored as a therapeutic target in clinical trials, suggests new treatment strategies for high-grade endometrial cancer. This finding holds particular significance for Martinique, where access to care is challenging.

Therapeutic effects of hAMSCs secretome on proliferation of MDA-MB-231 breast cancer cells by the cell cycle arrest in G1/S phase.

BACKGROUND: Cancer refers to a disease resulting from the uncontrolled division and growth of abnormal cells. Among different cancer types, breast cancer is considered as one of the most commonly diagnosed cancers. Herein, we explored the therapeutic effects of human amniotic mesenchymal stromal cells (hAMSCs) secretome on breast cancer cells (MDA-MB-231) through analyzing cell cycle progression. METHODS: We employed a co-culture system using 6-well Transwell plates and after 72 h, the cell cycle progression was evaluated in the hAMSCs-treated MDA-MB-231 cells through analyzing the expressions of RB, CDK4/6, cyclin D, CDK2, cyclin E, p16/INK4a, p21/WAF1/CIP1, and p27/KIP1 using quantitative real-time PCR (qRT-PCR) and western blot method. Cell proliferation, apoptosis, and cell cycle progression were checked using an MTT assay, DAPI staining, and flow cytometry. RESULTS: Our results indicated that elevation of RB, p21/WAF1/CIP1, and p27/KIP1 and suppression of RB hyperphosphorylation, p16/INK4a, cyclin E, cyclin D1, CDK2, and CDK4/6 may contribute to inhibiting the proliferation of hAMSCs-treated MDA-MB-231 cells through cell cycle arrest in G1/S phase followed by apoptosis. CONCLUSION: hAMSCs secretome may be an effective approach on breast cancer therapy through the inhibition of cell cycle progression.

IMP-1 inhibits renal cell carcinoma 786-O cell growth by targeting EphrinB2 signaling pathway

Abstract EphrinB2 plays a critical role in tumor growth. In this study, we studied the antitumor activity of imperatorin derivative IMP-1 in renal cell carcinoma (RCC) by regulating EphrinB2 pathway.. Results showed that IMP-1 inhibited the proliferation of 786-O cells in a dose- and time-dependent manner. More importantly, knockdown and transfection of EphrinB2 altered the inhibitory effect of IMP-1 on the activity of 786-O cells. IMP-1 arrested 786-O cell cycle at G0/G1 phase by decreasing the expression of cyclin D1 and cyclin E. Moreover, IMP-1 regulated Bcl-2 family proteins' expression, thus inducing apoptosis of 786-O cells. IMP-1 down-regulated the expression of EphrinB2, Syntenin1 and PICK1. Then, IMP-1 decreased the phosphorylation of Erk1/2 and AKT. In all, IMP-1 could regulate the EphrinB2 pathway in order to inhibit 786-O cell growth by arresting the cell cycle at G0/G1 phase and inducing cell apoptosis. Thus, IMP-1 may present as a potential strategy for RCC treatment.

Long noncoding RNA MGC27382 inhibits proliferation and metastasis of non-small cell lung cancer cells via down-regulating AKT/GSK3ß pathway.

PURPOSE: Persistent abnormal proliferation and long distant metastasis of tumors contribute to high mortality rate in non-small cell lung cancer (NSCLC) patients. Strategies that prevent NSCLC proliferation and/or metastasis have been studied but still need to be further explored. Numerous studies have proved the diversity functions of long noncoding RNAs (lncRNAs) exerted in cancer, including NSCLC. In this study, we aim to identify and investigate the role of novel lncRNAs in NSCLC progression. METHODS: RNA sequence data were retrieved from the Cancer Genome Atlas (TCGA), differentially expressed lncRNAs (DElncRNAs) were screened out based on the R language, then real-time PCR experiment was introduced to detect the DElncRNA expression levels. A series of experiments including MTT, cell cycle, transwell, and wound healing assays were employed to explore the effect of DElncRNA MGC27382 on cell proliferation and invasion ability. RESULTS: We detected that DElncRNA MGC27382 is down-regulated in NSCLC tissues and cells. Overexpression of MGC27382 prevented NSCLC cell proliferation via down-regulating cyclin D1 and cyclin E. Moreover, wound healing and transwell assays indicated that the ability of cell invasion and migration could be impaired when cells were treated with MGC27382 overexpression. Further studies demonstrated that MGC27382-mediated inhibition on NSCLC progression can be impaired by LY294002, which is a frequently used inhibitor of AKT/GSK3ß pathway. CONCLUSION: MGC27382 is down-regulated in NSCLC. It exerts an inhibitory role in NSCLC development through suppressing the AKT/GSK3ß pathway. Our results indicate that the lncRNA MGC27382 might be a tumor-suppressor gene in NSCLC. Overexpression of MGC27382 is thought to be a potential strategy for overcoming NSCLC progression.

TOP2A/MCM2, p16INK4a, and cyclin E1 expression in liquid-based cytology: a biomarkers panel for progression risk of cervical premalignant lesions.

BACKGROUND: To improve the efficiency of early diagnosis systems for cervical cancer, the use of cellular and viral markers for identifying precancerous lesions with a greater probability to progress to cancer has been proposed. Several cellular proteins and markers of oxidative DNA damage have been suggested as possible biomarkers of cervical carcinogenesis; however, they have not been evaluated together. In this study, we analyzed the expression of the cellular markers p16INK4a, Ki-67, CyclinE1, TOP2A/MCM2, and telomerase, as well as the DNA oxidative damage markers ROS and 8-OHdG. The analyses were performed in liquid-based cervical cytology samples or biopsies with premalignant lesions or cervical cancer diagnosis, with the purpose of selecting a panel of biomarkers that allow the identification of precursor lesions with greater risk of progression to cervical cancer. METHODS: We analyzed 1485 liquid-based cytology samples, including 239 non-squamous intraepithelial lesions (NSIL), 901 low-grade squamous intraepithelial lesions (LSIL), 54 high-grade squamous intraepithelial lesions (HSIL), and 291 cervical cancers (CC). The biomarkers were analyzed by immunocytochemistry and Human Papilloma Virus (HPV) genotyping with the INNO-LiPA genotyping Extra kit. RESULTS: We found that all tested cellular biomarkers were overexpressed in samples with high risk-HPV infection, and the expression levels increased with the severity of the lesion. TOP2A/MCM2 was the best biomarker for discriminating between LSIL and HSIL, followed by p16INK4a and cyclinE1. Statistical analysis showed that TOP2A/MCM2 provided the largest explanation of HSIL and CC cases (93.8%), followed by p16INK4a (91%), cyclin E1 (91%), Ki-67 (89.3%), and telomerase (88.9%). CONCLUSIONS: We propose that the detection of TOP2A/MCM2, p16INK4a and cyclin E1 expression levels is useful as a panel of biomarkers that allow identification of cervical lesions with a higher risk for progression to CC with high sensitivity and precision; this can be done inexpensively, in a single and non-invasive liquid-based cytology sample.

Impacto prognóstico de marcadores do ciclo celular em pacientes com carcinoma de ovário / Prognostic impact of cell cycle markers in ovarian cancer patients

A hiperexpressão da ciclina E1 (CCNE1h) foi identificada como um marcador de um subgrupo distinto de carcinoma ovariano seroso de alto grau (HGSC), caracterizado por ausência de deficiência de recombinação homóloga. Os inibidores Wee1 são inibidores do checkpoint G2-M e atuam principalmente em pacientes com tumores com defeitos no checkpoint G1-S. A associação entre CCNE1h e Wee1 ainda não foi avaliada. O objetivo deste estudo é avaliar a a expressão de ciclina E1 e Wee1 sua associação com as características clínicas e seu impacto prognóstico em um subconjunto institucional de pacientes brasileiras com diagnóstico de carcinoma de ovário.Também avaliamos em todo grupo institucional as características clínicas e seu impacto prognóstico e em um segundo subgrupo desta população o papel preditivo da expressão do intervalo livre de platina (PFI) e da ciclina E1 na eficácia do bevacizumabe. Realizamos uma revisão retrospectiva de dados clínicos de pacientes com câncer epitelial de ovário (EOC), tratados de janeiro de 2007 a janeiro de 2017 no A.C.Camargo Cancer Center. A CCNE1h e Wee1 foi avaliada por imunoistoquímica (IHC). As características das pacientes foram coletadas e os resultados clínicos medidos foram sobrevida livre de progressão (SLP), sobrevida global (SG), tempo para recidiva platino resistente, e intervalo livre de platina (PFI). Dos 196 pacientes com EOC, a ciclina E1 foi hiperexpressada em 83 pacientes (42%) e esse grupo apresentou características clínicas semelhantes as pacientes sem hiperexpressão. CCNE1h foi associada a menor mediana SGm 56,34 vs 88,08 meses (p = 0,06), menor SLP mediana (mSLP) 19,41 vs 22,47 meses (p = 0,37) e menor tempo mediano para recidiva platino resistente 50,72 vs 97,54 meses (p = 0,001). Foi feita uma subanálise das pacientes com recidiva platina sensível, tratadas com bevacizumabe e quimioterapia (grupo Bev) comparando-as com as tratadas apenas com quimioterapia (grupo CT) pareadas 1: 1 quanto ao intervalo livre de platina, número de linhas anteriores de quimioterapia e histologia. 124 pacientes foram pareadas, 62 em cada grupo. A SLPm foi de 19,5 meses para o grupo Bev vs. 16,0 meses para o grupo CT (p = 0,150). Na análise multivariada para SLP, o HR foi de 2,25 (IC95% 1,10-4,60) para a CCNE1h. O benefício do bevacizumabe estava presente apenas no subgrupo de pacientes com PFI <12 meses (SLPm 18,6 versus 10,4 meses, p = 0,002) e no subgrupo de pacientes com CCNE1h (mSLP 16,3 versus 7,0 meses, p = 0,010). As pacientes com CCNE1h apresentam pior tempo mediano para recidiva platino resistente. A expressão de Wee1 foi constante e na mesma intensidade para todas as pacientes. A IHC não parece ser um método apropriado para avaliar a atividade Wee1 no tecido tumoral. Concluimos portanto que a CCNE1h está associada à resistência à platina e à sobrevida global e que a CCNE1h e o PFI podem identificar pacientes com o maior benefício do bevacizumabe. Esses dados se confirmados em novos estudos podem ajudar a selecionar melhor os pacientes para terapia antiangiogênica.

Cyclin E1 overexpression (CCNE1h) has been identified as a marker of a distinct subgroup of high-grade serous ovarian carcinoma (HGSC) characterized by no homologous recombination deficiency. Wee1 inhibitors are G2-M check point inhibitors and act mostly in patients with tumors with G1-S defects. Association between CCNE1 and Wee1 has not been evaluated yet. The objective of this study is to evaluate the expression of cyclin E1 and Wee1 and their association with the clinical characteristics of patients and their prognostic impact in an institutional subset of Brazilian patients diagnosed with ovarian carcinoma. We also evaluated the clinical characteristics and their prognostic impact in every institutional group and in a second subgroup of this population the predictive role of platinum free interval (PFI) and E1 cyclin expression in the effectiveness of bevacizumab. A retrospective review of clinical data from epithelial ovarian cancer (EOC) patients treated from January 2007 to January 2017 at A.C.Camargo Cancer Center. CCNE1h and Wee1 overexpression were assessed by immunohistochemistry (IHC). Patients characteristics were collected, and measured clinical outcomes were progression-free survival (PFS), overall survival (OS), platinum resistant free survival (PRFS), platinum-free interval (PFI). Among 196 patients with EOC, cyclin E1 was overexpressed in 83 patients (42%) and this group had similar clinical characteristics to patients without CCNE1h. CCNE1h was associated with shorter median OS 56,34 vs 88,08 months (p =0.06), shorter mPFS 19,41 vs 22,47 months (p =0.37) and shorter mPRFS 50,72 vs 97,54 months (p =0.001). A subanalysis of patients with sensitive platinum recurrence treated with bevacizumab and chemotherapy (group Bev) was performed, comparing them with those treated only with chemotherapy (group CT) paired 1: 1 regarding the platinum free interval, number of previous lines of chemotherapy and histology. 124 patients were paired, 62 in each group.. Median PFS (mPFS) was 19.5 months for the Bev group vs. 16.0 months for CT group (p = 0.150). On multivariate analysis for PFS HR was 2.25 (95%CI 1.10-4.60) for CCNE1 overexpression. Benefit of bevacizumab was present only in the subgroup of patients with PFI < 12 months (mPFS 18.6 versus 10.4 months, p=0.002) and in the subgroup of patients with CCNE1 overexpression (mPFS 16.3 versus 7.0 months, p=0.010). CCNE1 overexpressed tumors have worse median time for resistant platinum recurrence. IHC does not seem to be an appropriate method to evaluate Wee1 activity in tumor tissue. We therefore conclude that CCNE1h is associated with platinum resistance and overall survival and that CCNE1h and PFI can identify patients with the greatest benefit from bevacizumab. These data if confirmed in new studies may help to better select patients for antiangiogenic therapy.

Genomic profiling in ovarian cancer retreated with platinum based chemotherapy presented homologous recombination deficiency and copy number imbalances of CCNE1 and RB1 genes.

BACKGROUND: Ovarian carcinomas presenting homologous recombination deficiency (HRD), which is observed in about 50% of cases, are more sensitive to platinum and PARP inhibitor therapies. Although platinum resistant disease has a low chance to be responsive to platinum-based chemotherapy, a set of patients is retreated with platinum and some of them are responsive. In this study, we evaluated copy number alterations, HR gene mutations and HR deficiency scores in ovarian cancer patients with prolonged platinum sensitivity. METHODS: In this retrospective study (2005 to 2014), we selected 31 patients with platinum resistant ovarian cancer retreated with platinum therapy. Copy number alterations and HR scores were evaluated using the OncoScan® FFPE platform in 15 cases. The mutational profile of 24 genes was investigated by targeted-NGS. RESULTS: The median values of the four HRD scores were higher in responders (LOH = 15, LST = 28, tAI = 33, CS = 84) compared with non-responders (LOH = 7.5, LST = 17.5, tAI = 23, CS = 47). Patients with high LOH, LST, tAI and CS scores had better response rates, although these differences were not statistically significant. Response rate to platinum retreatment was 22% in patients with CCNE1 gains and 83.5% in patients with no CCNE1 gains (p = 0.041). Furthermore, response rate was 54.5% in patients with RB1 loss and 25% in patients without RB1 loss (p = 0.569). Patients with CCNE1 gains showed a worse progression free survival (PFS = 11.1 months vs 3.7 months; p = 0.008) and a shorter overall survival (OS = 39.3 months vs 7.1 months; p = 0.007) in comparison with patients with no CCNE1 gains. Patients with RB1 loss had better PFS (9.0 months vs 2.6 months; p = 0.093) and OS (27.4 months vs 3.6 months; p = 0.025) compared with cases with no RB1 loss. Four tumor samples were BRCA mutated and tumor mutations were not associated with response to treatment. CONCLUSIONS: HR deficiency was found in 60% of our cases and HRD medium values were higher in responders than in non-responders. Despite the small number of patients tested, CCNE1 gain and RB1 loss discriminate patients with tumors extremely sensitive to platinum retreatment.

Phenylpropanoid-based sulfonamide promotes cyclin D1 and cyclin E down-regulation and induces cell cycle arrest at G1/S transition in estrogen positive MCF-7 cell line.

Cancer is one of the most critical problems of public health in the world and one of the main challenges for medicine. Different biological effects have been reported for sulfonamide-based compounds including antibacterial, antifungal, and antitumor activities. Herein, a series of phenylpropanoid-based sulfonamides (4a, 4a', 4b, 4b', 5a, 5a', 5b and 5b') were synthesized and their cytotoxic activity was evaluated against four cell lines derived from human tumours (A549 - lung, MCF-7 - breast, Hep G2 - hepatocellular carcinoma, and HT-144-melanoma). Cell viability was significantly reduced in the MCF-7 cell line when compounds 4b, 4b' and 5a were used; IC50 values were lower than those found for their precursors (eugenol and dihydroeugenol) and sulfanilamide. We observed that 4b induced cell cycle arrest at G1/S transition. This is probably due to its ability to reduce cyclin D1 and cyclin E expression. Moreover, 4b also induced apoptosis in MCF-7 cells as demonstrated by an increase in the cell population positive for annexin V in treated cultures in comparison to the control group. Taken together, the data showed that 4b is a promising antitumor agent and it should be considered for further in vivo studies.

Regulation of cyclin E1 expression in human pluripotent stem cells and derived neural progeny.

Human pluripotent stem cells (hPSCs), including embryonic and induced pluripotent stem cells (hESCs and hiPSCs) show unique cell cycle characteristics, such as a short doubling time due to an abbreviated G1 phase. Whether or not the core cell cycle machinery directly regulates the stemness and/or the differentiation potential of hPSCs remains to be determined. To date, several scenarios describing the atypical cell cycle of hPSCs have been suggested, and therefore there is still controversy over how cyclins, master regulators of the cell cycle, are expressed and regulated. Furthermore, the cell cycle profile and the expression pattern of major cyclins in hESCs-derived neuroprogenitors (NP) have not been studied yet. Therefore, herein we characterized the expression pattern of major cyclins in hPSCs and NP. We determined that all studied cyclins mRNA expression levels fluctuate along cell cycle. Particularly, after a thorough analysis of synchronized cell populations, we observed that cyclin E1 mRNA levels increased sharply in G1/S concomitantly with cyclin E1 protein accumulation in hPSCs and NP. Additionally, we demonstrated that cyclin E1 mRNA expression levels involves the activation of MEK/ERK pathway and the transcription factors c-Myc and E2Fs in hPSCs. Lastly, our results reveal that proteasome mediates the marked down-regulation (degradation) of cyclin E1 protein observed in G2/M by a mechanism that requires a functional CDK2 but not GSK3ß activity. ABBREVIATIONS: hPSCs: human pluripotent stem cells; hESCs: human embryonic stem cells; hiPSCs: human induced pluripotent stem cells; NP: neuroprogenitors; HF: human foreskin fibroblasts; MEFs: mouse embryonic fibroblasts; iMEFs: irradiated mouse embryonic fibroblasts; CDKs: cyclindependent kinases; CKIs: CDK inhibitors; CNS: central nervous system; Oct-4: Octamer-4; EB: embryoid body; AFP: Alpha-fetoprotein; cTnT: Cardiac Troponin T; MAP-2: microtubule-associated protein; TUJ-1: neuron-specific class III ß-tubulin; bFGF: basic fibroblastic growth factor; PI3K: Phosphoinositide 3-kinase; KSR: knock out serum replacement; CM: iMEF conditioned medium; E8: Essential E8 medium.

SALL2 represses cyclins D1 and E1 expression and restrains G1/S cell cycle transition and cancer-related phenotypes.

SALL2 is a poorly characterized transcription factor that belongs to the Spalt-like family involved in development. Mutations on SALL2 have been associated with ocular coloboma and cancer. In cancers, SALL2 is deregulated and is proposed as a tumor suppressor in ovarian cancer. SALL2 has been implicated in stemness, cell death, proliferation, and quiescence. However, mechanisms underlying roles of SALL2 related to cancer remain largely unknown. Here, we investigated the role of SALL2 in cell proliferation using mouse embryo fibroblasts (MEFs) derived from Sall2-/- mice. Compared to Sall2+/+ MEFs, Sall2-/- MEFs exhibit enhanced cell proliferation and faster postmitotic progression through G1 and S phases. Accordingly, Sall2-/- MEFs exhibit higher mRNA and protein levels of cyclins D1 and E1. Chromatin immunoprecipitation and promoter reporter assays showed that SALL2 binds and represses CCND1 and CCNE1 promoters, identifying a novel mechanism by which SALL2 may control cell cycle. In addition, the analysis of tissues from Sall2+/+ and Sall2-/- mice confirmed the inverse correlation between expression of SALL2 and G1-S cyclins. Consistent with an antiproliferative function of SALL2, immortalized Sall2-/- MEFs showed enhanced growth rate, foci formation, and anchorage-independent growth, confirming tumor suppressor properties for SALL2. Finally, cancer data analyses show negative correlations between SALL2 and G1-S cyclins' mRNA levels in several cancers. Altogether, our results demonstrated that SALL2 is a negative regulator of cell proliferation, an effect mediated in part by repression of G1-S cyclins' expression. Our results have implications for the understanding and significance of SALL2 role under physiological and pathological conditions.

Hexachlorobenzene alters cell cycle by regulating p27-cyclin E-CDK2 and c-Src-p27 protein complexes.

Hexachlorobenzene (HCB) is an organochlorine pollutant widely distributed in the environment around the entire world. Previous reports from our group and others have demonstrated that this compound is as an endocrine disruptor. We have also reported that HCB presents a co-carcinogenic effect in N-Nitroso-N-methyl-urea-induced mammary tumours in rats. In this work, we studied the effects of HCB on cell cycle progression and cell cycle regulating protein expression in the estrogen-sensitive breast cancer cell line, MCF-7. Here, we show that HCB alters cell cycle in a concentration-dependent way. The lowest assessed concentration (0.005µM) promotes the cell cycle progression, enhances cyclin D1 expression, and reduces the nuclear localization of p27 accompanied by an increased interaction between p27 and c-Src kinase. On the other hand, 5µM HCB delays the cell cycle progression and promotes the formation of the cyclin E-CDK2-p27 protein complex. Our results show that HCB stimulates cell proliferation through cell cycle modulation and c-Src involvement in MCF-7 cells. Here, we report for the first time that differential mechanisms of action of HCB on mammary cell cycle progression are triggered at different concentrations of this pollutant.

Cyclin E Deregulation and Genomic Instability.

Precise replication of genetic material and its equal distribution to daughter cells are essential to maintain genome stability. In eukaryotes, chromosome replication and segregation are temporally uncoupled, occurring in distinct intervals of the cell cycle, S and M phases, respectively. Cyclin E accumulates at the G1/S transition, where it promotes S phase entry and progression by binding to and activating CDK2. Several lines of evidence from different models indicate that cyclin E/CDK2 deregulation causes replication stress in S phase and chromosome segregation errors in M phase, leading to genomic instability and cancer. In this chapter, we will discuss the main findings that link cyclin E/CDK2 deregulation to genomic instability and the molecular mechanisms by which cyclin E/CDK2 induces replication stress and chromosome aberrations during carcinogenesis.

O papel da ciclina E1 no estresse replicativo e na instabilidade genômica em células epiteliais da mama / [The role of cyclin E1 in replicative stress and genomic instability in breast epithelial cells]

A ciclina E, juntamente com Cdk2, é um regulador importante da transição das fases G1/S do ciclo celular, promovendo o início e a progressão da síntese de DNA. Em alguns tipos de câncer, como o câncer de mama, os níveis de ciclina E se encontram desregulados, correlacionando com um estágio avançado do tumor e mau prognóstico. Níveis elevados de ciclina E interferem com a montagem de complexos pré-replicativos e retardam a progressão das forquilhas de replicação, levando ao fenômeno de estresse replicativo e eventualmente a instabilidade genômica. No entanto, as alterações genômicas causadas pela desregulação da ciclina E ainda não foram totalmente investigadas. Dados anteriores do nosso grupo demonstraram que altos níveis de ciclina E1 retardam a progressão pela fase S, permitindo que células entrem em mitose antes do término da replicação do DNA. A replicação incompleta do DNA induz aberrações cromossômicas em regiões genômicas específicas, como sítios frágeis. O objetivo deste projeto é avaliar o efeito da desregulação de ciclina E1 na instabilidade genômica de células epiteliais da mama ao longo da proliferação celular. Para estabelecer o modelo de estresse replicativo, células do epitélio da mama humana imortalizadas (HME1) foram transduzidas com adenovírus controle (Adv-Controle) ou com adenovírus que codifica o cDNA de ciclina E1 humana (Adv-Ciclina E1). Como controle positivo, foram utilizadas as linhagens celulares de câncer da mama SUM149PT e MDA-MB-157, que têm níveis aumentados de ciclina E1. Nossos resultados indicam que altos níveis de ciclina E1 não interferem com a proliferação de células HME1. Contudo, análises de citometria de fluxo indicam que altos níveis de ciclina E1 reduzem o número de células na fase G1, reduzem a progressão pela fase S e atrasam a entrada nas fases G2/M ao longo de 7 dias. A desregulação de ciclina E1 não induz a morte celular, mas induz eventos de poliploidia. Células HME1 tratadas com a afidicolina, um inibidor de DNA polimerase, progridem mais lentamente pela fase S, mas não apresentam alterações na morte celular ou poliploidia. Além disso, células HME1 com desregulação de ciclina E1 apresentam aberrações cromossômicas, como endorreduplicação, hiperfragmentação cromossômica e separação prematura de cromátides irmãs quando comparadas com células controle. No momento, estamos avaliando a instabilidade de sítios frágeis específicos em células HME1 com altos níveis de ciclina E1 usando Hibridização Fluorescente In Situ (FISH). Além disso, células HME1 com níveis elevados de ciclina E1 serão analisadas através de cariótipo por bandeamento G. O objetivo deste projeto é contribuir para a caracterização das alterações genéticas mediadas por ciclina E1 durante a carcinogênese da mama.

Molecular cloning and functional characterization of cyclin E and CDK2 from Penaeus monodon.

Reduced reproductive performance of the black tiger shrimp (Penaeus monodon) has caused economic losses and hampered the fishing industry. Detailed investigation of the molecular mechanism by which the cell cycle is regulated in this organism is needed to understand the development and maturation of ovaries and oocytes, with a view to improving reproductive capacity. Cell cycle progression is mainly determined by cyclin-dependent kinase (CDK) and cyclin complexes, the cyclin E/CDK2 complex playing a key role in G1/S transition. However, knowledge of the interplay between cyclin E and CDK2 in invertebrates remains limited. In this study, full-length P. monodon cyclin E (Pmcyclin E) and CDK2 (PmCDK2) sequences were cloned. The open reading frame of Pmcyclin E was 1263 bp in length and encoded a 47.9-kDa protein, while that of PmCDK2 was 921 bp, encoding a protein of 34.9 kDa. Recombinant cyclin E and CDK2 proteins were expressed in Escherichia coli and purified by Ni-chelating affinity chromatography. In addition, a pull-down assay was performed to identify any interaction between Pmcyclin E and PmCDK2. This research provides a basis for the study of the functional mechanisms of the cyclin E/CDK2 complex in shrimp, further enriching our knowledge of invertebrate cell cycle regulation.

NFAT1 transcription factor regulates cell cycle progression and cyclin E expression in B lymphocytes.

The NFAT family of transcription factors has been primarily related to T cell development, activation, and differentiation. Further studies have shown that these ubiquitous proteins are observed in many cell types inside and outside the immune system, and are involved in several biological processes, including tumor growth, angiogenesis, and invasiveness. However, the specific role of the NFAT1 family member in naive B cell proliferation remains elusive. Here, we demonstrate that NFAT1 transcription factor controls Cyclin E expression, cell proliferation, and tumor growth in vivo. Specifically, we show that inducible expression of NFAT1 inhibits cell cycle progression, reduces colony formation, and controls tumor growth in nude mice. We also demonstrate that NFAT1-deficient naive B lymphocytes show a hyperproliferative phenotype and high levels of Cyclin E1 and E2 upon BCR stimulation when compared to wild-type B lymphocytes. NFAT1 transcription factor directly regulates Cyclin E expression in B cells, inhibiting the G1/S cell cycle phase transition. Bioinformatics analysis indicates that low levels of NFAT1 correlate with high expression of Cyclin E1 in different human cancers, including Diffuse Large B-cell Lymphomas (DLBCL). Together, our results demonstrate a repressor role for NFAT1 in cell cycle progression and Cyclin E expression in B lymphocytes, and suggest a potential function for NFAT1 protein in B cell malignancies.

POD-1/TCF21 Reduces SHP Expression, Affecting LRH-1 Regulation and Cell Cycle Balance in Adrenocortical and Hepatocarcinoma Tumor Cells.

POD-1/TCF21 may play a crucial role in adrenal and gonadal homeostasis and represses Sf-1/SF-1 expression in adrenocortical tumor cells. SF-1 and LRH-1 are members of the Fzt-F1 subfamily of nuclear receptors. LRH-1 is involved in several biological processes, and both LRH-1 and its repressor SHP are involved in many types of cancer. In order to assess whether POD-1 can regulate LRH-1 via the same mechanism that regulates SF-1, we analyzed the endogenous mRNA levels of POD-1, SHP, and LRH-1 in hepatocarcinoma and adrenocortical tumor cells using qRT-PCR. Hereafter, these tumor cells were transiently transfected with pCMVMycPod-1, and the effect of POD-1 overexpression on E-box elements in the LRH-1 and SHP promoter region were analyzed by ChIP assay. Also, Cyclin E1 protein expression was analyzed to detect cell cycle progression. We found that POD-1 overexpression significantly decreased SHP/SHP mRNA and protein levels through POD-1 binding to the E-box sequence in the SHP promoter. Decreased SHP expression affected LRH-1 regulation and increased Cyclin E1. These findings show that POD-1/TCF21 regulates SF-1 and LRH-1 by distinct mechanisms, contributing to the understanding of POD-1 involvement and its mechanisms of action in adrenal and liver tumorigenesis, which could lead to the discovery of relevant biomarkers.

Anti-tumour effects of elatol, a marine derivative compound obtained from red algae Laurencia microcladia.

OBJECTIVES: This paper aims to evaluate the anti-tumour properties of elatol, a compound (sesquiterpene) isolated from algae Laurencia microcladia. METHODS: In-vitro and in-vivo anti-tumour properties of elatol were investigated using: MTT assays to assess the cytotoxic effects; flow cytometry analysis to examine the cell cycle and apoptosis; Western blot analysis for determination of the expression of cell cycle and apoptosis proteins; and study of in-vivo tumour growth in mice (C57Bl6 mice bearing B16F10 cells). KEY FINDINGS: Elatol exhibited a cytotoxic effect, at least in part, by inducing cell cycle arrest in the G(1) and the sub-G(1) phases, leading cells to apoptosis. Western blot analysis demonstrated that elatol reduced the expression of cyclin-D1, cyclin-E, cyclin-dependent kinase (cdk)2 and cdk4. A decrease in bcl-xl and an increase in bak, caspase-9 and p53 expression was also observed. In the in-vivo experiment, treatment with elatol was able to reduce tumour growth in C57Bl6 mice. CONCLUSIONS: Elatol promotes a delay in the cell cycle, probably in the G(1)/S transition, activating the apoptotic process and this could be responsible, at least in part, for the in-vivo effects observed. Taken together, the in-vitro and in-vivo experiments suggested that elatol has anti-tumour properties. Further studies should be conducted to clarify the mechanism of action.

Downregulation of the tumor-suppressor miR-16 via progestin-mediated oncogenic signaling contributes to breast cancer development.

INTRODUCTION: Experimental and clinical evidence points to a critical role of progesterone and the nuclear progesterone receptor (PR) in controlling mammary gland tumorigenesis. However, the molecular mechanisms of progesterone action in breast cancer still remain elusive. On the other hand, micro RNAs (miRNAs) are short ribonucleic acids which have also been found to play a pivotal role in cancer pathogenesis. The role of miRNA in progestin-induced breast cancer is poorly explored. In this study we explored progestin modulation of miRNA expression in mammary tumorigenesis. METHODS: We performed a genome-wide study to explore progestin-mediated regulation of miRNA expression in breast cancer. miR-16 expression was studied by RT-qPCR in cancer cell lines with silenced PR, signal transducer and activator of transcription 3 (Stat3) or c-Myc, treated or not with progestins. Breast cancer cells were transfected with the precursor of miR-16 and proliferation assays, Western blots or in vivo experiments were performed. Target genes of miR-16 were searched through a bioinformatical approach, and the study was focused on cyclin E. Reporter gene assays were performed to confirm that cyclin E 3'UTR is a direct target of miR-16. RESULTS: We found that nine miRNAs were upregulated and seven were downregulated by progestin in mammary tumor cells. miR-16, whose function as a tumor suppressor in leukemia has already been shown, was identified as one of the downregulated miRNAs in murine and human breast cancer cells. Progestin induced a decrease in miR-16 levels via the classical PR and through a hierarchical interplay between Stat3 and the oncogenic transcription factor c-Myc. A search for miR-16 targets showed that the CCNE1 gene, encoding the cell cycle regulator cyclin E, contains conserved putative miR-16 target sites in its mRNA 3' UTR region. We found that, similar to the molecular mechanism underlying progestin-modulated miR-16 expression, Stat3 and c-Myc participated in the induction of cyclin E expression by progestin. Moreover, overexpression of miR-16 abrogated the ability of progestin to induce cyclin E upregulation, revealing that cyclin E is a novel target of miR-16 in breast cancer. Overexpression of miR-16 also inhibited progestin-induced breast tumor growth in vitro and in vivo, demonstrating for the first time, a role for miR-16 as a tumor suppressor in mammary tumorigenesis. We also found that the ErbB ligand heregulin (HRG) downregulated the expression of miR-16, which then participates in the proliferative activity of HRG in breast tumor cells. CONCLUSIONS: In this study, we reveal the first progestin-regulated miRNA expression profile and identify a novel role for miR-16 as a tumor suppressor in progestin- and growth factor-induced growth in breast cancer.

Role of Kupffer cells in thioacetamide-induced cell cycle dysfunction.

It is well known that gadolinium chloride (GD) attenuates drug-induced hepatotoxicity by selectively inactivating Kupffer cells. In the present study the effect of GD in reference to cell cycle and postnecrotic liver regeneration induced by thioacetamide (TA) in rats was studied. Two months male rats, intraveously pretreated with a single dose of GD (0.1 mmol/Kg), were intraperitoneally injected with TA (6.6 mmol/Kg). Samples of blood and liver were obtained from rats at 0, 12, 24, 48, 72 and 96 h following TA intoxication. Parameters related to liver damage were determined in blood. In order to evaluate the mechanisms involved in the post-necrotic regenerative state, the levels of cyclin D and cyclin E as well as protein p27 and Proliferating Cell Nuclear Antigen (PCNA) were determined in liver extracts because of their roles in the control of cell cycle check-points. The results showed that GD significantly reduced the extent of necrosis. Noticeable changes were detected in the levels of cyclin D1, cyclin E, p27 and PCNA when compared to those induced by thioacetamide. Thus GD pre-treatment reduced TA-induced liver injury and accelerated the postnecrotic liver regeneration. These results demonstrate that Kupffer cells are involved in TA-induced liver and also in the postnecrotic proliferative liver states.

E2F1-mediated upregulation of p19INK4d determines its periodic expression during cell cycle and regulates cellular proliferation.

BACKGROUND: A central aspect of development and disease is the control of cell proliferation through regulation of the mitotic cycle. Cell cycle progression and directionality requires an appropriate balance of positive and negative regulators whose expression must fluctuate in a coordinated manner. p19INK4d, a member of the INK4 family of CDK inhibitors, has a unique feature that distinguishes it from the remaining INK4 and makes it a likely candidate for contributing to the directionality of the cell cycle. p19INK4d mRNA and protein levels accumulate periodically during the cell cycle under normal conditions, a feature reminiscent of cyclins. METHODOLOGY/PRINCIPAL FINDINGS: In this paper, we demonstrate that p19INK4d is transcriptionally regulated by E2F1 through two response elements present in the p19INK4d promoter. Ablation of this regulation reduced p19 levels and restricted its expression during the cell cycle, reflecting the contribution of a transcriptional effect of E2F1 on p19 periodicity. The induction of p19INK4d is delayed during the cell cycle compared to that of cyclin E, temporally separating the induction of these proliferative and antiproliferative target genes. Specific inhibition of the E2F1-p19INK4d pathway using triplex-forming oligonucleotides that block E2F1 binding on p19 promoter, stimulated cell proliferation and increased the fraction of cells in S phase. CONCLUSIONS/SIGNIFICANCE: The results described here support a model of normal cell cycle progression in which, following phosphorylation of pRb, free E2F induces cyclin E, among other target genes. Once cyclinE/CDK2 takes over as the cell cycle driving kinase activity, the induction of p19 mediated by E2F1 leads to inhibition of the CDK4,6-containing complexes, bringing the G1 phase to an end. This regulatory mechanism constitutes a new negative feedback loop that terminates the G1 phase proliferative signal, contributing to the proper coordination of the cell cycle and provides an additional mechanism to limit E2F activity.