ABCC2 (MRP2, cMOAT) Localized in the Nuclear Envelope of Breast Carcinoma Cells Correlates with Poor Clinical Outcome

Nuclear expression of ABCC2 can be specific for lower differentiated cells and stem cells. The study aimed at examination of ABCC2 expression in breast cancers. The immunohistochemical analyses were performed on 70 samples of breast cancer. We have also studied prognostic value of the ABCC2 mRNA expression using the KM plotter which assessed the effect of 22,277 genes on survival in 1809 breast cancer patients. Immunohistochemical studies demonstrated that ABCC2 expression may be manifested in nuclear envelope of neoplastic cells (ABCC2n) as well as in their cell membrane and cytoplasm (ABCC2c). The univariate and multivariate analyses showed that higher expression of ABCC2n and ABCC2c was typical for cases of a shorter overall survival time. Higher ABBC2n expression was also typical for cases of a shorter disease-free survival and a shorter progression-free time. The KM plotter analysis of the prognostic value of ABCC2 mRNA expression showed that elevated ABCC2 expression was specific for cases of a shorter relapse-free survival only in the estrogen receptor-negative subgroup. The study demonstrated hat breast cancers manifest ABCC2 expression and that it is linked to a less favourable prognosis. Our results suggested that immunohistochemical tests represent a reliable way to detect prognostic value of ABCC2 expression, allowing to demonstrate differences related to subcellular localization of the protein. Cases with nuclear expression of ABCC2 manifested a more aggressive clinical course, which might reflect a less advanced differentiation of neplastic cells, resistance to the applied cytostatic drugs and tamoxifen.     

Role of multidrug resistance protein 2 (MRP2) in chemoresistance and clinical outcome in oesophageal squamous cell carcinoma

Background:

Although multidrug resistance protein 2 (MRP2) confers chemoresistance in some cancer types, its implication on oesophageal squamous cell carcinoma (ESCC) remains unclear.

Methods:

We evaluated MRP2 expression by immunohistochemistry and RT–PCR using 81 resected specimens from ESCC patients who did or did not receive neo-adjuvant chemotherapy (NACT), including 5-fluorouracil, doxorubicin, and cisplatin (CDDP). Correlation between MRP2 expression and response to chemotherapy was also examined in 42 pre-therapeutic biopsy samples and eight ESCC cell lines.

Results:

MRP2-positive immunostaining was more frequently observed in ESCCs with NACT than in those without NACT (27.3 vs 5.4%). The MRP2-positive patients showed poorer prognosis than MRP2-negative patients (5-year survival rate, 25.6 vs 55.7%). Concordantly, ESCC with NACT showed 2.1-fold higher mRNA expression of MRP2 than those without NACT (P=0.0350). In pre-therapeutic biopsy samples of patients with NACT, non-responders showed 2.9-fold higher mRNA expression of MRP2 than responders (P=0.0035). Among the panel of ESCC cell lines, TE14 showed the highest MRP2 mRNA expression along with the strongest resistance to CDDP. Inhibition of MRP2 expression by small-interfering RNA reduced chemoresistance to CDDP.

Conclusion:

Our data suggested that MRP2 is one of molecules, which regulate the sensitivity to chemotherapy including CDDP in advanced ESCC patients.     

MRP2 (ABCC2) transports taxanes and confers paclitaxel resistance and both processes are stimulated by probenecid

ATP binding cassette (ABC) multidrug transporters such as P-glycoprotein (P-gp, ABCB1) and BCRP (ABCG2) confer resistance against anticancer drugs and can limit their oral availability, thus contributing to failure of chemotherapy. Like P-gp and BCRP, another ABC transporter, MRP2 (ABCC2), is found in apical membranes of pharmacologically important epithelial barriers and in a variety of tumors. MRP2 transports several anticancer drugs and might thus have a similar impact on chemotherapy as P-gp and BCRP. We here show that human MRP2 transduced into epithelial MDCKII cells efficiently transported the taxane anticancer drugs paclitaxel and docetaxel and that this transport could be substantially stimulated with the drug probenecid, a representative of a range of MRP2-stimulating drugs. Transport of 2 previously identified MRP2 substrates, etoposide and vinblastine, was likewise stimulated by probenecid. MRP2 further conferred substantial resistance against paclitaxel toxicity, and this resistance was 2.7-fold stimulated by probenecid. Our data indicate that MRP2 function might affect chemotherapy with taxanes, potentially influencing both tumor resistance and taxane pharmacokinetics. Moreover, coadministration of probenecid and other MRP2-stimulating drugs might lead to unforeseen drug-drug interactions by stimulating MRP2 function, potentially leading to suboptimal levels of taxanes and other anticancer drugs in plasma and tumor.     

Characterization of the drug resistance and transport properties of multidrug resistance protein 6 (MRP6, ABCC6)

Mutations in human multidrug resistance protein 6 (MRP6, ABCC6), a member of the MRP family of drug efflux pumps, are the genetic basis of Pseudoxanthoma elasticum, a disease that affects elastin fibers in the skin, retina, and blood vessels. However, little is known about the functional characteristics of the protein, including its potential activity as a resistance factor for anticancer agents. Here, we report the results of investigations of the in vitro transport properties and drug resistance activity of MRP6. Using membrane vesicles prepared from Chinese hamster ovary cells transfected with MRP6 expression vector, it is shown that expression of MRP6 is specifically associated with the MgATP-dependent transport of the glutathione S-conjugates leukotriene C(4) and S-(2, 4-dinitrophenyl)glutathione and the cyclopentapeptide BQ123 but not glucuronate conjugates such as 17beta-estradiol 17-(beta-D-glucuronide). Analysis of the drug sensitivity of MRP6-transfected cells revealed low levels of resistance to several natural product agents, including etoposide, teniposide, doxorubicin, and daunorubicin. These results indicate that MRP6 is a glutathione conjugate pump that is able to confer low levels of resistance to certain anticancer agents.     

多药耐药相关蛋白及肺耐药蛋白在人直肠癌组织中的表达及临床意义

目的　检测多药耐药相关蛋白（ＭＲＰ） 及肺耐药蛋白（ＬＲＰ） 在人直肠癌组织中的表达,探讨其与临床分期、分化程度及预后的关系。方法　采用免疫组织化学技术法检测５７ 例人直肠癌组织中ＭＲＰ及ＬＲＰ的表达。结果　５７ 例人直肠癌组织中可检测到ＭＲＰ表达者２８ 例,占４９．１ ％ ;ＬＲＰ表达者２４ 例,占４２．１ ％ ;二者同时表达者１０ 例,占１７ ．５％ ;有ＭＲＰ或ＬＲＰ表达者４２ 例,占７３ ．７ ％ ;两蛋白表达阳性率与肿瘤分期、分化程度无显著相关（ Ｐ＞ ０ ．０５） 。ＭＲＰ表达阳性者术后生存期明显低于该蛋白阴性者（ Ｐ＜ ０．０５） ,而ＬＲＰ的表达则与预后无显著相关;两蛋白表达无明显相关性（ Ｐ＞ ０．０５） 。结论　ＭＲＰ可能是判断人直肠癌预后的指标之一,对直肠癌患者综合治疗的实施具有指导意义。     

Expression of MRP and cMOAT in childhood neuroblastomas and malignant liver tumors and its relevance to clinical behavior.

Advanced neuroblastoma and malignant liver tumor are representative childhood cancers for which combined chemotherapy including cisplatin and doxorubicin is routinely performed. The prognosis of patients with tumors which develop multiple drug resistance (MDR) is unfavorable. To elucidate the role of multidrug resistance-associated protein (MRP) and canalicular multispecific organic anion transporter (cMOAT) in the clinical behavior of the tumors, we examined 42 neuroblastomas and 10 malignant liver tumors for the expressions of MRP and cMOAT by quantitative RNA-polymerase chain reaction (PCR). The amplification and expression of N-myc oncogene in the neuroblastomas were also investigated. We found a close association between MRP and N-myc expression in each neuroblastoma sample but no significant relationship between MRP expression and the patients' outcome. The forced expression of N-myc failed to enhance the expression of MRP in N-myc transfected neuroblastoma cell lines. cMOAT was rarely expressed in the neuroblastomas, but was frequently expressed in the malignant liver tumors. The expression of MRP and cMOAT in the childhood liver tumors was more common and higher, especially in advanced cases with a poor outcome, than that observed in normal liver or in 9 hepatocellular carcinomas from adult patients. The enhanced expression of these genes might be characteristic of childhood malignant liver tumors and related to their clinical chemoresistance.     

Increased cyclooxygenase-2 (COX-2) expression is associated with chemotherapy resistance and outcome in ovarian cancer patients.

BACKGROUND: Cyclooxygenase-2 (COX-2) expression is associated with aggressive clinicopathological parameters and unfavourable prognosis in several human malignancies. The aim of this study was to investigate the expression of COX-2 and its association with clinicopathological parameters, response to treatment, and clinical outcome in ovarian cancer patients. PATIENTS AND METHODS: COX-2 expression was analysed by immunohistochemistry in 87 primary ovarian carcinomas from patients with measurable disease after primary laparotomy. RESULTS: COX-2 immunoreaction was observed in 39 (44.8%) cases, and did not differ in distribution according to age, FIGO stage, debulking at time of surgery, presence of ascites, histotype or tumour grade. Both in patients cytoreduced at first surgery and in those undergoing only explorative laparotomy, the percentage of COX-2 positivity was significantly higher in non-responding than in patients responding to treatment (P = 0.043 and P = 0.0018, respectively). In multivariate analysis, only COX-2 positivity and older age retained an independent role in predicting a poor chance of response to treatment. There was no significant difference of clinical outcome according to COX-2 status in patients undergoing primary debulking while, in the subgroup of patients who underwent explorative laparotomy, COX-2-positive cases showed a shorter time to progression (P = 0.025) and overall survival (P = 0.025). CONCLUSIONS: The assessment of COX-2 status could provide additional information in order to identify ovarian cancer patients with a poor chance of response to chemotherapy and potentially candidates for more individualised treatments.     

Clinical outcome in localized renal cell carcinomas related to immunoexpression of proliferating cell nuclear antigen, Ki-67 antigen, and tumor size.

This study was designed to clarify the relationship between clinical outcome and immunoexpression of proliferating cell nuclear antigen (PCNA) and Ki-67 antigen (Ki-67) in 71 localized renal cell carcinomas (RCCs) of Robson stage I and II, related to the disease recurrence and tumor size. PCNA and Ki-67 expressions showed significant differences between non-recurring and recurring groups and more variability in stage II than in stage I. Recurrence rates according to tumor size were 0% for /=5.0 cm. It was concluded that PCNA and Ki-67 expression profiles were considered to be closely related to tumor stage and showed some promise for predicting the disease recurrence.     

多药耐药相关蛋白及肺耐药蛋白在人直肠癌组织中的表达及临床 …

目的 检测多药耐药相关蛋白（ＭＲＰ）及肺耐药蛋白（ＬＲＰ）在人直肠癌组织中的表达,探讨其与临床分期、分化程度及预后的关系。方法 采用免疫组织化学技术法检测５７例人直肠癌组织中ＭＲＰ及ＬＲＰ的表达。结果 ５７例人直肠癌组织中可检测到ＭＲＰ表达者２８例,占４９．１％;ＬＲＰ表达者２４例,占４２．１％;二者同时表达者１０例,占１７．５％;有ＭＲＰ或ＬＲＰ表达者４２例,占７３．７％;两蛋白表达阳性率与肿瘤     

ABCC4/MRP4和ABCC5/MRP5基因在NK/T细胞淋巴瘤的表达及与临床疗效的关系

背景与目的：NK/T细胞淋巴瘤(natural killer/T cell lymphoma)疗效差,多药耐药(multidrug resistance,MDR)的产生是引起肿瘤产生耐药和化疗疗效降低及失败的原因之一,本文通过研究多药耐药相关蛋白4(ABCC4 multidrug resistance associated protein,ABCC4/MRP)基因和多药耐药相关蛋白5(ABCC5 multidrug resistance associated protein,ABCC5/MRP)基因在NK/T细胞淋巴瘤SNK-6、YTS细胞株和组织中的表达情况,结合临床疗效了解其与预后的关系。方法：应用实时荧光定量PCR(real-time PCR)技术和免疫组织化学法(immunohistochemistry,IHC)检测ABCC4/MRP4、ABCC5/MRP5基因mRNA和蛋白表达水平。结果：与正常NK细胞相比,ABCC4/MRP4、ABCC5/MRP5基因在SNK-6、YTS细胞株中高表达(P<0.05);与鼻炎组织相比,ABCC4/MRP4、ABCC5/MRP5基因在NK/T细胞淋巴瘤患者组织中高表达(P<0.05);ABCC4/MRP4、ABCC5/MRP5基因表达量的高低和临床疗效呈负相关(P<0.05)。结论：ABCC4/MRP4、ABCC5/MRP5基因及其表达蛋白影响NK/T细胞淋巴瘤的疗效。     

Clinical correlates of MDR1 (P-glycoprotein) gene expression in ovarian and small-cell lung carcinomas.

BACKGROUND: Expression of the MDR1 (P-glycoprotein) gene causes resistance to several classes of lipophilic anti-cancer drugs, but MDR1 expression in untreated ovarian and lung carcinomas is rarely detectable by standard assays. PURPOSE: This study was designed to measure the MDR1 messenger RNA (mRNA) content of ovarian and lung carcinomas and to analyze clinical correlations of MDR1 expression in these tumors. METHODS: A sensitive assay based on the polymerase chain reaction (PCR) was used in a retrospective study to measure MDR1 mRNA in biopsy samples of 100 solid tumors, including 60 ovarian and 32 lung carcinomas. The levels of MDR1 mRNA were correlated with history of chemotherapeutic treatment for all tumors; for ovarian and small-cell lung carcinomas (SCLCs), these levels were also correlated with subsequent tumor response to chemotherapy. RESULTS: Among previously untreated patients, MDR1 mRNA was expressed in 68% (50 of 74) of all tumors. Among patients pretreated with chemotherapy regimens that included at least one P-glycoprotein-transported drug (MDR regimens), 95% (20 of 21) of all tumors expressed MDR1 mRNA though the incidence of high-level MDR1 expression was decreased among the treated tumors. MDR1 mRNA was expressed in only one of five tumors treated with regimens that included no P-glycoprotein substrates (non-MDR regimens). Subsequent tumor response to chemotherapy was evaluated in 35 patients with ovarian carcinoma and seven patients with SCLC. The presence of even very low levels of MDR1 mRNA correlated with the lack of response to MDR regimens in these tumor types (P < .035 for ovarian carcinomas, P < .029 for SCLCs, and P < .0005 for both tumor types; Fisher's Exact Test). CONCLUSIONS: Low-level expression of MDR1 mRNA correlates with clinical resistance to combination chemotherapy in ovarian cancer and SCLC. We hypothesize that MDR1 is expressed in a subpopulation of more malignant tumor cells possessing multiple mechanisms of drug resistance. IMPLICATIONS: The presence of MDR1-expressing tumor cells may be useful as a predictive marker for clinical resistance to combination chemotherapy in ovarian cancer and SCLC. Prospective studies are needed to confirm this hypothesis.     

Copper-transporting P-type adenosine triphosphatase (ATP7B) as a cisplatin based chemoresistance marker in ovarian carcinoma: comparative analysis with expression of MDR1, MRP1, MRP2, LRP and BCRP

Intrinsic or acquired resistance to chemotherapy is the major obstacle to overcome in the treatment of patients with solid carcinoma. Cisplatin is one of the most effective chemotherapeutic agents for treating ovarian carcinoma. Recently, copper-transporting P-type adenosine triphosphatase (ATP7B) has been demonstrated as one of the genes responsible for cisplatin resistance in vitro. We hypothesized that the expression of ATP7B gene increases resistance to cisplatin in ovarian carcinoma and a priori knowledge of its expression is important for the choice of therapy. The aim of our study was to assess the role of ATP7B gene in ovarian carcinoma and compare its expression with those of multidrug resistance-related transporters such as MDR1, MRP1, MRP2, LRP and BCRP genes. The transporters' gene expression profiles from 82 patients treated with cisplatin-based chemotherapy after surgery were assessed by RT-PCR. We did not observe any significant correlation between ATP7B gene expression and those of MDR1, MRP1, MRP2, LRP or BCRP. The expression level of ATP7B gene was significantly increased (p < 0.05) in patients with moderately-/poorly-differentiated ovarian carcinomas treated with cisplatin-based chemotherapy, thus ATP7B may serve as an independent prognostic factor in these patients. In contrast, the expression level of MDR1, MRP1, MRP2, LRP and BCRP genes were not prognostic indicators of disease. These findings suggest that ATP7B gene may be considered as a novel chemoresistance marker and that inhibitor(s) of ATP7B might be useful, in patients with ovarian carcinoma treated with cisplatin-based chemotherapy.     

Individual and combined roles of CYP3A, P-glycoprotein (MDR1/ABCB1) and MRP2 (ABCC2) in the pharmacokinetics of docetaxel

Docetaxel is one of the most widely used anticancer drugs. A major problem with docetaxel treatment, however, is the considerable interpatient variability in docetaxel exposure. Another disadvantage of the drug is that it has a very low oral bioavailability and can, therefore, only be administered intravenously. The drug-metabolizing enzyme CYP3A and the drug transporter MDR1 (P-glycoprotein) are major determinants of docetaxel pharmacokinetics. In vitro studies have indicated that docetaxel is also a substrate for the drug transporter MRP2, but the in vivo importance of MRP2 for docetaxel is currently unknown. We, therefore, investigated the role of MRP2 in the pharmacokinetics of docetaxel by utilizing Mrp2(-/-) mice. We also generated and characterized Cyp3a/Mdr1a/b/Mrp2(-/-) combination knockout mice to get more insight into how these drug-handling systems work together in determining docetaxel pharmacokinetics. The systemic exposure in Mrp2(-/-) mice was not significantly different from wild-type, after either oral or intravenous administration. Strikingly, however, in Cyp3a/Mdr1a/b/Mrp2(-/-) mice, systemic docetaxel exposure was increased 166-fold after oral administration when compared with wild-type mice, and 2.3-fold when compared with Cyp3a/Mdr1a/b(-/-) mice. Interestingly, this 166-fold increase was disproportionate compared with that for the separate Cyp3a (12-fold) or Mdr1a/b/Mrp2 (4-fold) knockouts. The oral bioavailability was increased to 73% in the Cyp3a/Mdr1a/b/Mrp2(-/-) strain, versus only 10% in wild-type mice. Our data thus indicate that in the absence of CYP3A and Mdr1a/b activity, Mrp2 has a marked impact on docetaxel pharmacokinetics. These findings could have important implications for improving the oral bioavailability and reducing the variability in docetaxel exposure.     

Ovarian serous carcinomas acquire cisplatin resistance and increased invasion through downregulation of the high-temperature-required protein A2 (HtrA2), following repeated treatment with cisplatin

High-temperature-required protein A2 (HtrA2) is one of the serine proteases related to apoptosis. HtrA2 protein expression has been associated with cisplatin resistance and poor prognosis in ovarian serous adenocarcinoma (SAC). The aim of this study was to understand the influence of HtrA2 on repeated treatment with cisplatin. The change in HtrA2 expression in 31 ovarian cancers was investigated by immunohistochemical analysis, before and after cisplatin-based chemotherapy, and the association between HtrA2 expression after chemotherapy and prognosis was analyzed. The association between the change in HtrA2 and proteins associated with LATS1 in ovarian serous cancer cell lines after repeated treatment with cisplatin was evaluated in vitro. In immunohistochemical analysis, repeated cisplatin treatment induced downregulation of HtrA2 protein expression, before and after cisplatin-based chemotherapy in SAC. Progression-free survival and overall survival of SAC with low expression of HtrA2 were worse than those with high expression. In vitro analysis using cisplatin-sensitive ovarian cancer cell lines, KF28, and cisplatin-resistant cancer cell lines, KFr13, obtained from KF28 by repeated cisplatin treatment, showed that HtrA2 protein expression was lower in KFr13 than in KF28. Furthermore, KFr13 had a higher invasive capacity than KF28. Next, downregulation of HtrA2 transfected with an HtrA2-specific siRNA in KF28 had not only cisplatin resistance, but also more invasive capacity than those with non-specific siRNA. Repeated treatment with cisplatin downregulated the HtrA2 protein, which led to cisplatin resistance and increased invasive capacity. Thus, HtrA2 might be a biomarker of response to cisplatin treatment and prognosis, after cisplatin-based chemotherapy.     

Activity and expression of the multidrug resistance proteins P-glycoprotein, MRP1, MRP2, MRP3 and MRP5 in de novo and relapsed acute myeloid leukemia.

The multidrug resistance proteins (MRPs) MRP1, MRP2, MRP3, MRP5 and P-glycoprotein (P-gp) act in concert with each other to give a net resultant pump function in acute myeloid leukemia (AML). The aim of the present study was to analyze the activity of these proteins, which might be upregulated at relapse as compared with de novo AML due to clonal selection. The mRNA expression and activity of P-gp and the MRPs were determined with RT-PCR and flow cytometry, in conjunction with phenotype, as measured with the monoclonal antibodies CD34, CD38 and CD33, in 30 paired samples of de novo and relapsed AML. P-gp and MRP activity varied strongly between the cases (rhodamine 123 efflux-blocking by PSC833: 5.4+/-7.7, and carboxyfluorescein efflux-blocking by MK-571: 4.3+/-6.7, n = 60). P-gp and MRP activity were increased in 23% and 40% of the relapse samples, and decreased in 30% and 20% of the relapse samples, respectively (as defined by a difference of >2 x standard deviation of the assays). Up- or downregulation of mRNA expression was observed for MDR1 (40%), MRP1 (20%), MRP2 (15%), MRP3 (30%), and MRP5 (5%). Phenotyping demonstrated a more mature phenotype in 23% of the relapsed AML cases, and a more immature phenotype in 23% of the relapses, which was independent of the karyotypic changes that were observed in 50% of the studied cases. P-gp and MRP activity correlated with the phenotypic changes, with higher P-gp and MRP activities in less mature cells (r = -0.66, P < 0.001 and r = -0.31, P = 0.02, n = 58). In conclusion, this study shows that P-gp and MRP activity are not consistently upregulated in relapsed AML. However, P-gp and MRP activities were correlated with the maturation stage as defined by immune phenotype, which was observed to be different in 46% of the relapses.     

Associations of ABCB1, ABCC2, and ABCG2 polymorphisms with irinotecan-pharmacokinetics and clinical outcome in patients with advanced non-small cell lung cancer

BACKGROUND: The authors investigated whether ABCB1, ABCC2, and ABCG2 genetic polymorphisms affect pharmacokinetics (PK) of irinotecan and treatment outcome of patients with advanced nonsmall cell lung cancer (NSCLC). METHODS: Blood samples from 107 NSCLC patients treated with irinotecan and cisplatin chemotherapy were used for genotyping ABCB1 (1236C > T, 2677G > T/A, 3435C > T), ABCC2 (-24C > T, 1249G > A, 3972C > T), and ABCG2 (34G > A, 421C > A) polymorphisms. Genotypes were correlated with irinotecan-PK, toxicity, tumor response, and survival. RESULTS: Among 8 polymorphisms, 3435TT and 2677TT were associated with AUC(SN-38G) and CL(SN-38G). When haplotypes are assigned, 2677TT/3435TT carriers showed significantly lower AUC(SN-38G) (P = .006), whereas 2677GG/3435CC carriers showed significantly higher AUC(SN-38) (P = .039). These findings suggest that 2677TT and 3435TT variants are associated with higher efflux activity. In toxicity, the 2677G/T or A was associated with grade 4 neutropenia. The 2677GG carriers showed significantly lower absolute neutrophil count during the 1(st) cycle (P = .012) as well as entire course of chemotherapy (P = .042). The 3435TT was associated with higher frequency of grade 3 diarrhea (P = .047). In tumor response, ABCC2 -24TT and 3972TT genotypes were associated with higher response rates (P = .031 and .046, respectively) and longer progression-free survival (P = .035 and .038, respectively), which was sustained in haplotype analysis. CONCLUSIONS: Specific polymorphisms of ABCB1 and ABCC2 can influence disposition and tumor response to irinotecan by regulating transporter activity. These findings may help to individualize irinotecan-based chemotherapy in patients with advanced NSCLC.