FLT3-ITD and MLL-PTD influence the expression of MDR-1, MRP-1, and BCRP mRNA but not LRP mRNA assessed with RQ-PCR method in adult acute myeloid leukemia.

Fms-like tyrosine kinase 3-internal tandem duplication (FLT3-ITD) and mixed-lineage leukemia gene-partial tandem duplication (MLL-PTD) are aberrations associated with leukemia which indicate unsatisfactory prognosis. Downstream regulatory targets of FLT3-ITD and MLL-PTD are not well defined. We have analyzed the expression of MDR-1, multidrug resistant protein-1 (MRP-1), breast cancer resistance protein (BCRP), and lung resistance protein (LRP) messenger RNA (mRNA) in relation to the mutational status of FLT3-ITD and MLL-PTD in 185 acute myeloid leukemia (AML) adult patients. The real-time quantitative polymerase chain reaction method was performed to assess the expression of the MDR-1, MRP-1, BCRP, and LRP mRNA, and the results were presented as coefficients calculated using an intermediate method according to Pfaffl's rule. Significantly higher expressions of MDR-1 mRNA were found in patients who did not harbor FLT3-ITD (0.20 vs. 0.05; p = 0.0001) and MRP-1 mRNA in patients with this mutation (0.96 vs. 0.70; p = 0.002) and of BCRP mRNA in patients with MLL-PTD (0.61 vs. 0.38; p = 0.03). In univariate analysis, the high expression of MDR-1 mRNA (≥0.1317) negatively influenced the outcome of induction therapy (p = 0.05), whereas the high expression of BCRP mRNA (≥1.1487) was associated with a high relapse rate (RR) (p = 0.013). We found that the high expression of MDR-1 (≥0.1317), MRP-1 (≥0.8409), and BCRP mRNA (≥1.1487) significantly influenced disease-free survival (DFS; p = 0.059, 0.032, and 0.009, respectively) and overall survival (0.048, 0.014, and 0.059, respectively). Moreover, a high expression of BCRP mRNA (≥1.1487) proved to be an independent prognostic factor for RR (p = 0.01) and DFS (p = 0.002) in multivariate analysis. The significant correlation between the expression of MDR-1, MRP-1, and BCRP mRNA and FLT3-ITD or MLL-PTD in AML patients requires further investigation.

BCL-2, in combination with MVP and IGF-1R expression, improves prediction of clinical outcome in complete response cervical carcinoma patients treated by radiochemotherapy.

OBJECTIVES: To investigate whether BCL-2 expression would improve MVP/IGF-1R prediction of clinical outcome in cervix carcinoma patients treated by radiochemotherapy, and suggest possible mechanisms behind this effect. METHODS: Fifty consecutive patients, who achieved complete response to treatment, from a whole series of 60 cases suffering from non-metastatic localized cervical carcinoma, were prospectively included in this study from July 1999 to December 2003. Follow-up was closed in January 2011. All patients received pelvic radiation (45-64.80 Gy in 1.8-2 Gy fractions) with concomitant cisplatin at 40 mg/m2/week doses followed by brachytherapy. Oncoprotein expression was studied by immunohistochemistry in paraffin-embedded tumour tissue. RESULTS: No relation was found between BCL-2 and clinicopathological variables. High MVP/IGF-1R/BCL-2 tumour expression was strongly related to poor local and regional disease-free survival (P<0.0001), distant disease-free survival (P=0.010), disease-free survival (P<0.0001), and cause-specific survival (P<0.0001). NHEJ repair protein Ku70/80 expression was significantly repressed in tumours overexpressing all three oncoproteins (P=0.047). No differences were observed in proliferation (Ki67 expression) or P53 alteration. CONCLUSIONS: BCL-2, MVP, and IGF-1R overexpression were related to poorer clinical outcome in cervical cancer patients who achieved clinical complete response to radiochemotherapy. The NHEJ repair protein Ku70/80 expression could be involved in the regulation of these oncoproteins.

Expression of lung resistance protein and multidrug resistance-related protein (MRP1) in pediatric acute lymphoblastic leukemia.

Multidrug resistance (MDR) is a phenomenon by which cells become resistant to unrelated chemotherapeutic agents. The prognostic value that lung resistance protein (LRP) and multidrug resistance-related protein 1 (MRP1) have in the setting of pediatric acute lymphoblastic leukemia (ALL) is controversial. The aim of this study was to investigate the expression of LRP and MRP1 and effect on clinical outcome and prognosis. The mRNA expression of LRP and MRP1 were analyzed in leukemic blasts of 34 pediatric ALL patients. LRP and MRP1 mRNA expression were detected in 41.2% and 35.3%, respectively. Eleven (91.7%) of 12 patients without LRP achieved CR compared with 9 (50.0%) of 18 with LRP expression. Similarly, 11 (100%) of 11 patients without MRP1 expression achieved CR compared with 9 (47.4%) of 19 with MRP1 expression and higher LRP expression rate or MRP1 expression rate was present in patients with relapse than MDR genes negative patients. The expression of either of two genes was associated with poorer 2-year survival. Also, patients expressing both genes had poorer outcomes and had worse 2-year survival. We suggest that MDR expression affects complete remission and survival rates in ALL patients. Thus, diagnosis appears to provide prognostic information for pediatric ALL.

Expression of the multidrug resistance protein MRP and the lung-resistance protein LRP in nasal NK/T cell lymphoma: further exploring the role of P53 and WT1 gene.

AIMS: Nasal NK/T-cell lymphoma (NKTL) is relatively common in the adult men of Asia. Many patients with nasal NKTL have poor response to therapy. Some of them show P-glycoprotein over-expression. To investigate the expression of other multidrug resistance proteins (MDR) and possible regulatory factors in nasal NKTL, the clinical and pathological features are described. METHODS: Thirty Chinese adults with nasal NKTL are presented. Immunohistochemical study was carried out to detect multidrug resistance-associated protein 1 (MRP) and lung resistance-related protein (LRP). The association between possible regulatory proteins (P53 and WT1) and MDR were explored. In situ hybridisation for Epstein-Barr virus (EBV) detection, polymerase chain reaction assay for T-cell receptor gene and direct sequencing for the P53 gene were performed. RESULTS: Seven (23.3%) and eight (26.7%) patients showed immunoreactivity of MRP and LRP, respectively. Positive staining for both markers was identified in 6.7% (2 cases). The EBV was detected in most cases (97%). Twenty-six (86.7%) cases expressed positive nuclear staining of P53. However, of the cases analysed for P53 mutation, none showed a mutaion at the hot spots studied. WT1 protein was not detected in the nasal NKTL. CONCLUSION: Our study reports expression of MRP and LRP in nasal NKTL. The over-expression of P53 is probably associated with high incidence of EBV infection and unlikely a regulatory protein for the expression of MRP and LRP. Further studies are necessary to validate the association between P53 mutation and expression of MRP and LRP in nasal NKTL.

Lung resistance-related protein (LRP) predicts favorable therapeutic outcome in Acute Myeloid Leukemia.

There is conflicting evidence that MDR1, MRP2 and LRP expression is responsible for chemotherapy resistance. We conducted this study to explore their role in AML therapy outcomes. Bone marrow and peripheral blood samples of 90 AML patients, receiving chemotherapy, were analyzed by real time PCR. Gene expression was calculated by the 2-ΔΔCt method. The patients who had a persistent remission were labelled 'Good Responder' (GRes) whereas, those with relapse or drug resistance were labelled 'Poor Responders' (PRes). Higher LRP expression in bone marrow, but not in peripheral blood, was positively associated with persistent remission (p = 0.001), GRes (p = 0.002), 1-year overall as well as disease-free survival (p = 0.02 and p = 0.007, respectively). Marrow and blood MDR1 and MRP2 expression did not differ significantly between the above groups. Logistic regression analysis showed that only a diagnosis of acute promyelocytic leukemia (APL; M3) or high marrow LRP expression significantly predicted a favorable therapeutic outcome. This is the first report showing that high bone marrow LRP expression predicts significant favorable therapeutic outcome. Peripheral blood LRP expression as well as marrow and blood MDR1 and MRP2 expression have no predictive value in AML patients treated with standard dose cytarabine and daunorubicin 3+7 regimen.

Major vault protein is a direct target of Notch1 signaling and contributes to chemoresistance in triple-negative breast cancer cells.

Resistance to chemotherapy remains a significant problem in the treatment of breast cancer, especially for triple-negative breast cancer (TNBC), in which standard systemic therapy is currently limited to chemotherapeutic agents. Our study aimed to better understand the molecular mechanisms that lead to failure of chemotherapy in TNBC. Herein, we observed elevated expression of Notch1 and major vault protein (MVP) in MDA-MB-231DDPR cells compared to their parental counterparts. We demonstrated that Notch1 could positively regulate the expression of MVP. Also, Notch1 intracellular domain (ICD) was capable of binding to CBF-1 on the promoter of MVP to drive its transcription, resulting in activation of AKT pathway and promoting the progress of epithelial to mesenchymal transition (EMT). Conversely, silencing of Notch1 and MVP suppressed AKT pathway, reduced EMT and enhanced the sensitivity of TNBC cells to cisplatin and doxorubicin. Survival analysis indicated that the MVP was closely related to shorter recurrence-free survival (RFS) in patients with TNBC. Collectively, this study provides evidence that Notch1 activates AKT pathway and promotes EMT partly through direct activation of MVP. Targeting Notch1/MVP pathway appears to have potential in overcoming chemoresistance in TNBC.

Immunohistochemical expression of multidrug resistance proteins in mature T/NK-cell lymphomas.

Multidrug resistance (MDR) is defined as resistance of tumor cells to a wide spectrum of structurally and functionally unrelated drugs. One of the most important mechanisms in mediating MDR is that involving cellular drug efflux transporters. Drug resistance is a common and formidable obstacle to therapy in mature T/NK-cell lymphomas and the MDR phenotype is thought to be one of the contributing mechanisms. In this study we assessed the immunohistochemical expression of P-gp (P-glycoprotein), MRP-1 (multidrug resistance associated protein 1), BCRP (breast cancer resistance protein) and LRP (lung resistance protein) in 45 mature T/NK-cell lymphomas diagnosed at our hospital. We detected P-gp expression in 31% (13/42), MRP-1 expression in 74% (31/42), BCRP in 78% (32/41) and LRP in 59% (26/44) of the cases. These findings show that our T/NK-cell lymphoma cases display high frequency of MDR protein expression.

Expression of multidrug-resistance-related proteins P-glycoprotein, glutathione-S-transferases, topoisomerase-II and lung resistance protein in primary gastric cardiac adenocarcinoma.

AIM: Multidrug resistance (MDR) is closely correlated to an unfavorable prognosis in various human cancers. However, the clinical significance of the expression of MDR-related proteins p-glycoprotein (PGP), glutathione-s-transferases (GST-pi), topoisomerase-II (Topo-II) and lung resistance protein (LRP) in primary gastric cardiac adenocarcinoma (PGCA) remains unclear. In this present study, the total of the four kinds of MDR-related proteins mentioned above were detected by using immunohistochemistry, and their clinical significance in chemoresistance were also investigated. METHODS: This retrospective study included 69 resected specimens from patients with PGCA. The expression of PGP, GST-pi, Topo-II and LRP in formalin-fixed paraffin-embedded tissue sections was determined by a labelled streptavidin-biotin immunohistochemical technique, and the results were analyzed in correlation with clinicopathological data. None of these patients received chemotherapy prior to surgery. RESULTS: The positive rates of expression of PGP, GST-pi, Topo-II and LRP in malignant tissues (49.2%, 75.4%, 68.1% and 58%, respectively) were all higher than that of the normal tissues(0, 30%, 20% and 0, respectively, P < 0.01). PGP expression in tumors that had metastasized was significantly more frequent than in tumors that had not metastasized (67.5% vs 24.1%, P < 0.01). The expression of PGP was closely related with clinicopathologic staging (staging 1/2 vs 3/4, 28.6% vs 58.3%, P < 0.05). No significant correlation was shown between PGP and increasing differentiated degree (40%, 42.4% and 61.5%, P > 0.05). GST-pi expression status progressively increased with increasing differentiated degree (40%, 75.8% and 88.5%, P < 0.05) and clinicopathologic stage (staging 1/2 vs 3/4, 57.1% vs 83.3%, P < 0.05). In addition, a significant positive correlation was also observed between GST-pi and lymphatic metastasis (with vs. without metastasis, 87.5% vs 58.6%, P < 0.05). The expression of Topo-II was associated with increasing differentiated degree (33.3%, 69.7 and 80.7%, P < 0.01). No significant differences with Topo-II expression were found in relation to the clinicopathologic stage (staging 1/2 vs 3/4, 57.1% vs 72.9%, P > 0.05) and lymphatic metastasis (with vs. without metastasis, 65.0% vs 72.4%, P > 0.05). Moreover, a significant difference with the expression of LRP was found in relation to the clinicopathologic stage (staging 1/2 vs 3/4, 38% vs 66.6%, P < 0.05), and lymphatic metastasis (with vs without metastasis, 70.0% vs 41.4%, P < 0.05). Comparing the well, moderately and poorly differentiated cohort, a non-statistical increasing trend towards LRP expression status was noted (50.0%, 54.5% and 65.3%, respectively, P > 0.05). Besides, the co-expression of all four tested MDR-related proteins also existed. The positive rates of co-expression of PGP and GST-pi, PGP and Topo-II, PGP and LRP, GST-pi and Topo-II, LRP and GST-pi, LRP and Topo-II, PGP, GST-pi, Topo-II and LRP in malignant cells were 23.2%, 15.9%, 11.6%, 13.0, 26.1, 7.24, 5.8, respectively. CONCLUSIONS: MDR-related proteins PGP, GST-pi, Topo-II alpha and LRP are involved in multiple mechanisms of drug resistance in PGCA. Combined determination of PGP, GST-pi, Topo-II and LRP may be prospectively valuable for optimizing the chemotherapy regimes, developing high quality anti-cancer drugs, and further predicting the outcomes of those patients with PGCA.

MVP expression is related to IGF1-R in cervical carcinoma patients treated by radiochemotherapy.

OBJECTIVE: To assess the expression of MVP in cervix carcinoma patients treated by radiochemotherapy, its relation to clinical and pathologic prognostic factors and its role in predicting clinical outcome. In addition the relation to IGF-1R expression in this cohort of patients will be explored. MATERIALS AND METHODS: Sixty consecutive patients suffering from localized cervix carcinoma were prospectively included in this study from July 1999 to December 2003. Follow-up was closed in November 2007. Patients were staged following the TNM classification. All patients received pelvic radiation (45-64.80 Gy in 1.8-2 Gy fractions) followed brachytherapy and concomitant cisplatin at 40 mg/m(2)/week doses. MVP expression was studied by immunohistochemistry in paraffin-embedded tumour tissue. RESULTS: MVP was expressed in 58 patients (96.7%) and no relation was found with clinicopathological variables. High MVP expression was related to high IGF1-R expression (p=0.023). Complete response after treatment was observed in 50 patients (83.3%). Clinical stage of the disease and clinical response to radiochemotherapy were the most important prognostic factors related to survival. High MVP and IGF-1R tumour expression was strongly related to poor local and regional disease-free survival (p=0.006), distant disease-free survival (p=0.050), disease-free survival (p=0.006), and cause-specific survival (p=0.007) in patients achieving a complete response. CONCLUSION: MVP and IGF-1R expression were related in clinical cervical tumours and confer reduced long-term local control in patients who achieved clinical complete response to radiochemotherapy.

Multidrug resistance proteins in renal cell carcinoma.

A large number of renal cancer patients show poor or partial response to chemotherapy and the precise mechanism has not been understood yet. MDR is the principal mechanism by which many cancers develop resistance to chemotherapeutic drugs and is associated with the elevated expression of MDR proteins. These are divided into two groups: ABC transporters and non-ABC transporters. The aim of our study was to determine the expression of MDR1/Pgp, MRP1 and LRP in 47 samples of renal cell carcinomas using immunohistochemical assay. Our results were analysed in relation to nuclear grade and other clinical and pathological parameters to see the possible correlation between the expression of MDR proteins and factors mentioned above. The majority of renal carcinoma specimens showed positivity for MDR proteins. In this regard, 21 % of samples revealed positive results for MDR1, 62 % for MRP1 and 76.6 % for LRP protein. Furthermore, our study displayed significant differences between MDR1, LRP and nuclear grade. On the other hand, no association was found between MRP1 and nuclear grade, as well as between the expression of three MDR proteins and other clinically relevant parameters.

MVP immunohistochemistry is a useful adjunct in distinguishing leiomyosarcoma from leiomyoma and leiomyoma with bizarre nuclei.

Morphologically, distinguishing between leiomyoma (LM) and leiomyosarcoma (LMS) is not always straightforward, especially with benign variants such as bizarre leiomyoma (BLM). To identify potential markers of malignancy in uterine smooth muscle tumors, proteomic studies were performed followed by assessment of protein expression by immunohistochemistry. Archival formalin-fixed, paraffin-embedded tissues from tumors (n = 23) diagnosed as LM, BLM, and LMS (using published criteria) were selected for the study. Sequential window acquisition of all theoretical fragment ion spectra mass spectrometry was applied to pooled samples of formalin-fixed, paraffin-embedded LM and LMS tumor tissue to assay the relative protein quantities and look for expression patterns differentiating the 2 tumor types. A total of 592 proteins were quantified, and 10 proteins were differentially expressed between LM and LMS. Select proteins were chosen for evaluation by immunohistochemistry (IHC) based on antibody availability and biologic relevance in the literature. IHC was performed on a tissue microarray, and intensity was evaluated using imaging software. Major vault protein (MVP) and catechol O-methyltransferase had 3.05 and 13.94 times higher expression in LMS relative to LM by sequential window acquisition of all theoretical fragment ion spectra mass spectrometry, respectively. By IHC, MVP (clone 1014; Santa Cruz Biotechnology, Dallas, TX) was found to be 50% sensitive and 100% specific when comparing LMS to LM. Catechol O-methyltransferase (clone FL-271; Santa Cruz Biotechnology) had a sensitivity of 38% and a specificity of 88%. Six of 7 BLM had expression of MVP similar to LM. Immunohistochemical staining for MVP is a useful adjunct in distinguishing LMS from LM and BLM in difficult cases.

Immunolocalization and cell expression of lung resistance-related protein (LRP) in normal and tumoral human respiratory cells.

Lung resistance-related protein (LRP) is an integral part of the multidrug resistance (MDR) phenotype involved in cell resistance toward xenobiotics or chemotherapy. The aim of this study was to compare the intracellular localization and cell expression of LRP in normal bronchial cells and their tumoral counterparts from non-small cell lung cancer (NSCLC). LRP expression was also investigated concurrently with DNA ploidy and chromosome 16 (lrp gene locus) aberrations. Confocal microscopy showed that LRP localization was exclusively intracytoplasmic regardless of the cell type and was never observed in the nuclear pore complex. Flow cytometry demonstrated a similar level of LRP expression in normal bronchial cells and in cancer cells from NSCLC samples. FISH analysis, performed to evaluate the number of chromosome 16 and lrp loci, demonstrated a significant gain of chromosome 16 in DNA aneuploid tumors. Furthermore, we did not find any link between LRP expression and DNA ploidy status or chromosome 16 number. These results suggest that LRP expression observed in NSCLC, maintained through the carcinogenesis process of respiratory cells, is not altered by the increased number of copies of chromosome 16 and probably controlled by mechanisms different from those of MRP1 expression, whereas both proteins are associated with the MDR phenotype.

Biological comparison of ovarian cancer resistant cell lines to cisplatin and Taxol by two different administrations.

Drug resistance is one of the major obstacles to chemotherapy of ovarian cancer. Studies with cell lines can serve as an initial screen for agents that might modulate drug resistance. To establish more appropriate models of drug resistance and explore whether the differences exist in the different drug resistant sublines selected by different treatments, we induced SKOV3 cell line using cisplatin (CDDP) and Taxol over a period of 16 months by the pulse (SKOV3/CDDP-P and SKOV3/Taxol-P) and intermittent incremental (SKOV3/CDDP-80 and SKOV3/Taxol-25) method, respectively. The resistant phenotype of the four resistant sublines, SKOV3/CDDP-P, SKOV3/CDDP-80, SKOV3/Taxol-P and SKOV3/Taxol-25, was very stable and the resistance index was 4.12, 11.50, 261.98 and 622.76, respectively. In cell morphology, the cells from pulse treatment had remarkable changes compared with the cells from intermittent incremental treatment. SKOV3/CDDP-80 and SKOV3/Taxol-P grew more slowly than SKOV3/CDDP-P and SKOV3/Taxol-25. Multidrug resistance gene 1, multidrug resistance protein 1, lung resistance protein and glutathione S-transferase pi mRNA expression of SKOV3/CDDP-P and SKOV3/Taxol-25 had greater changes than that of SKOV3/CDDP-80 and SKOV3/Taxol-P. The results suggest there are great differences between the resistant cell lines resulting from pulse and intermittent incremental method. The resistant cells selected by the intermittent method were more resistant than the cells selected by the pulse method. The two resistant sublines selected by the pulse method may serve as appropriate models for the study of mechanisms of drug resistance in ovarian cancer.

Activity of bortezomib in adult de novo and relapsed acute myeloid leukemia.

BACKGROUND: Bortezomib is an inhibitor of proteasome and NF-kappaB, with activity in various solid tumors and hematological malignancies. AIM: The aim of the study was the analysis of in vitro drug resistance to bortezomib and other anticancer drugs in de novo and relapsed adult acute myeloid leukemia (AML). PATIENTS AND METHODS: The leukemic cells of 46 adult patients with AML were tested for the in vitro drug resistance profile. The group included 20 de novo and 26 relapsed AML patients, among whom, 12 relapsed after allogeneic hematopoietic stem cell transplantation (HSCT) and 4 after autologous HSCT. The MTT assay was performed for 21 drugs. Expression of P-glycoprotein (PGP), multidrug resistance-associated protein-1 (MRP1) and lung resistance protein (LRP) proteins was measured by flow cytometry. RESULTS: No significant differences in drug resistance were found for all tested drugs between de novo and relapsed AML samples, while expression of PGP, MRP1 and LRP was higher in relapsed patients. Patients with refractory or relapsed disease, had higher resistance of myeloblasts to cyclophosphamide (RR = 2.4, p = 0.050), and better sensitivity to busulfan (RR = 0.4, p = 0.054) and topotecan (RR = 0.4, p = 0.031). Those who have died due to refractory/relapsed disease (n = 16) had better sensitivity to bortezomib (RR = 0.6, p = 0.046) and treosulfan (RR = 0.1, p = 0.018). CONCLUSION: In vitro drug resistance in relapsed adult AML is comparable to that in de novo disease. Activity in vitro of bortezomib might be a rationale for its use in refractory/relapsed AML adult patients.

In vitro evaluation of zoledronic acid resistance developed in MCF-7 cells.

BACKGROUND: Zoledronic acid is an important osteotropic compound used in combination with anticancer agents to reduce the incidence of hypercalcemia and skeletal morbidity in patients with advanced breast cancer and bone metastases. Ineffectiveness of anticancer drugs during chemotherapy is a frequently observed situation in cancer chemotherapy. The resistance of tumor cells to more than one cytotoxic drugs is defined as multidrug resistance. Drug resistance may be caused by altered gene expression levels and altered activities of proteins related to drug transport or cell death. MATERIALS AND METHODS: To investigate the potential development of zoledronic acid resistance in breast cancer, parental MCF-7 cells were selected by increasing doses of zoledronic acid. MTT cytotoxicity assays, RT-PCR and Western blot were performed. The anticancer drugs paclitaxel, docetaxel, vincristine and doxorubicin were tested in combination to assess their combined antiproliferative effects and cross-resistance profiles. RESULTS: Results demonstrated that the drug-adapted cells are resistant to zoledronic acid compared to parental MCF-7 and de novo expression of resistance genes, such as BCRP and LRP, were found. Up-regulation of Bcl-2 gene expression in resistant cells was also found. Synergistic cytotoxic effects of the combination of zoledronic acid with paclitaxel, docetaxel and vincristine were confirmed by fractional inhibitory indices, and zoledronic acid resistant cells were also found to be cross-resistant to these agents. CONCLUSION: Zoledronic acid may cause resistance in MCF-7 cells. Overexpression of BCRP and LRP genes and an increase in Bcl-2 gene expression may have roles in the development of zoledronic acid resistance in the MCF-7 cell line. On the other hand, MDR1 and MRP1 genes do not seem to contribute to the zoledronic acid resistance significantly.

[Expression of proteins associated with multidrug resistance and resistance to chemotherapy in lung cancer]. / Expresión de proteínas relacionadas con resistencia a múltiples fármacos y resistencia a la quimioterapia en el cáncer de pulmón.

OBJECTIVE: Membrane transporters are proteins that play a crucial role in resistance to chemotherapy. The aim of this study was to assess the influence of membrane transporter protein expression on chemotherapeutic response. MATERIAL AND METHODS: One hundred and forty seven samples of tumor tissue were collected from 143 patients; 35 samples were obtained by bronchoscopy and 112 were surgical specimens. A total of 101 samples from 99 patients were adequate for study. Cryopreserved samples were subjected to immunohistochemical analysis to detect 3 proteins associated with multidrug resistance: P-glycoprotein (Pgp), multidrug-resistance-associated protein 1 (MRP1), and lung resistance protein (LRP). RESULTS: In 16 cases none of the proteins were expressed. A single protein was expressed in 32 (3 Pgp, 11 MRP1, and 18 LRP); 2 in 34 cases (24 Pgp and LRP; 5 MRP1 and Pgp; 5 MRP1 and LRP); and all 3 in 17 cases. No significant relationship was found between age and the expression of Pgp (P=.74), MRP1 (P=.95), or LRP (P=.26). Nor were there significant differences in number (P=.72) or type of coexpressed proteins (P=.39) by sex, by tumor stage (number, P=.55; type, P=.21), or by tumor grade (number, P=.59; type, P=.51). There was a highly significant trend toward coexpression of Pgp and LRP (P< .01) but not of Pgp and MRP1 (P=.18) or MRP1 and LRP (P=.26). MRP1 was expressed less often in adenocarcinoma. LRP was expressed less often in squamous cell carcinoma than in adenocarcinoma and undifferentiated large cell carcinoma. Coexpression of Pgp, MRP1, and LRP was observed most often in squamous cell carcinoma. CONCLUSIONS: Proteins associated with multidrug resistance are commonly expressed in lung cancer. Of the 3 proteins studied, LRP was the one most often found. Coexpression of more than 1 of the proteins was found in a considerable percentage of patients. Pgp was mainly found to be coexpressed with LRP. Pgp expression and the number of coexpressed proteins seemed to have a negative impact on response to chemotherapy.

The roles of four multi-drug resistance proteins in hepatocellular carcinoma multidrug resistance.

The roles of multi-drug resistance protein 1 (MDR1), multi-drug resistance related protein 1 (MRP1), lung resistance protein (LRP) and breast cancer resistance protein (BCRP) in the multi-drug resistance (MDR) of hepatocellular carcinoma (HCC) were studied. By exposing HepG2 cell line to progressively increased concentrations of adriamycin (ADM), HepG2 multi-drug resistant subline (HepG2/ADM) was induced. The MDR index of HepG2/ADM was detected by using MTT. The expressions of the four MDR proteins in the three cell lines (L02, HepG2, HepG2/ADM) were investigated at mRNA and protein levels by real-time RT-PCR and Western blot respectively. Our results showed that when the ADM concentration was under 100 microg/L, HepG2 could easily be induced to be drug-resistant. The IC(50) of the HepG2/ADM to ADM was 282 times that of HepG2. The expression of MDR1 and BCRP mRNA in HepG2/ADM cells were 400 and 9 times that of HepG2 cells respectively while there was no difference in the mRNA expressions of MRP1 and LRP. There was no difference between HepG2 and L02 cells in the mRNA expressions of the four genes. At the protein level, the expressions of MDR1, BCRP and LRP but MRP1 in HepG2/ADM were significantly higher than those of HepG2 and L02. Between HepG2 and L02, there was no difference in the expressions of four genes at the protein level. HepG2/ADM is a good model for the study of MDR. The four genes are probably the normally expressed gene in liver. The expressions of MDR1 and BCRP could be up-regulated by anti-cancer agents in vitro. The MDR of HCC was mainly due to the up-regulation of MDR1 and BCRP but MRP1 and LRP. These findings suggest they may serve as targets for the reversal of MDR of HCC.

Association between single nucleotide polymorphisms of drug resistance-associated genes and response to chemotherapy in advanced ovarian cancer.

BACKGROUND: Single nucleotide polymorphisms (SNPs) may show clinicopathological importance as prognostic markers. This study examined the association of SNPs and the expression of drug resistance-associated markers with response to chemotherapy in advanced ovarian cancer (stages III and IV) patients. MATERIALS AND METHODS: SNPs were analyzed for MDR1, MRP1, MRP2 and LRP in 60 advanced ovarian cancer patients. The protein expression of each factor was analyzed by immunohistochemistry in all patients. RESULTS: As a result of examining the relevance of SNP genotypes to the response to chemotherapy, a significant relevance (p=0.01) was observed regarding MRP1 exon-17 SNP (G2168A) involving amino acid substitution. No significant relationship was observed between protein expression and the response to chemotherapy or disease-free survival time. CONCLUSION: Analysis of drug resistance gene polymorphism appears to be an indicator of the response to chemotherapy in advanced ovarian cancer.

The association of increased lung resistance protein expression with acquired etoposide resistance in human H460 lung cancer cell lines.

Chemoresistance remains the major obstacle to successful therapy of cancer. In order to understand the mechanism of multidrug resistance (MDR) that is frequently observed in lung cancer patients, here we studied the contribution of MDR-related proteins by establishing lung cancer cell lines with acquired resistance against etoposide. We found that human H460 lung cancer cells responded to etoposide more sensitively than A549 cells. Among MDR-related proteins, the expression of p-glycoprotein (Pgp) and lung resistance protein (LRP) were much higher in A549 cells compared with that in H460 cells. When we established H460-R1 and -R2 cell lines by progressive exposure of H460 cells to increasing doses of etoposide, the response against etoposide as well as doxorubicin was greatly reduced in R1 and R2 cells, suggesting MDR induction. Induction of MDR was not accompanied by a decrease in the intracellular accumulation of etoposide and the expression of MDR-related proteins that function as drug efflux pumps such as Pgp and MRP1 was not changed. We found that the acquired resistance paralleled an increased expression of LRP in H460 cells. Taken together, our data suggest the implicative role of LRP in mediating MDR in lung cancer.

[The clinical significance of P-glycoprotein, lung resistance protein and multidrug resistance related protein expressions in infiltrating breast carcinoma tissues].

OBJECTIVE: Our purpose was to explore clinical significance of three kinds of drug resistance related proteins, including P-glycoprotein (P-gp), lung resistance protein (LRP), multidrug resistance related protein (MRP) expressions in infiltrating breast carcinoma tissues. METHODS: Flow cytometry was used to analyze the expression of drug resistance related proteins in carcinoma tissues and corresponding para-carcinoma tissues from 68 primary infiltrating breast carcinoma patients. RESULTS: The relative fluorescence intensity (RFI) expressed by median (M) of P-gp, LRP and MRP in breast carcinoma tissues were 0.58, 0.51and 0.56 respectively. In corresponding para-carcinoma tissues, their expression level were 0.26, 0.33 and 0.30. Their difference were obvious (P < 0.05). There were not notable differences of drug resistance related protein expressions in different ages, different tumor sizes, different pathological types, different clinical stages, estrogen receptor or progestin receptor negative and positive patients (P > 0.05). The expressions of P-gp and MRP in lymph node metastasis positive patients were 0.61and 0.69, in lymph node metastasis negative patients they were 0.54 and 0.45. There were no notable differences of P-gp and MRP expression in lymph node metastasis negative and positive patients. The expression of LRP (M = 1.49) was higher in lymph node metastasis positive patients than that in negative patients (M = 0.50, P < 0.05). The correlation analysis showed that there was positive correlation between the expression of LRP and MRP in breast carcinoma tissues (P < 0.05). CONCLUSION: The clinical significance of three kinds of drug resistance related protein expressions had differences in infiltrating breast carcinoma tissues. The expression of LRP had related with lymph node metastasis status and had positive correlation with MRP expression. It can become a target in forecasting breast carcinoma prognosis.