Drug Resistance In Bladder Cancer Research Articles

Nuclear expression of Y box binding-1 is important for resistance to chemotherapy including gemcitabine in TP53-mutated bladder cancer.

The development and acquisition of multiple drug resistance in cancer cells remain a major obstacle in the treatment of bladder cancer. Nuclear translocation of Y box binding-1 (YB-1), which is a member of a family of DNA-binding proteins that contain a cold shock domain, plays a significant role in the acquisition of drug resistance by upregulating expression of the multidrug resistance-1 (MDR-1) gene product, p-glycoprotein. The tumor suppressor protein p53 is thought to be essential for nuclear translocation of YB-1. We hypothesized that nuclear translocation of YB-1 might be associated with drug resistance of bladder cancer with an abnormality of the TP53 gene that results in a mutated p53 protein. To test this hypothesis, we analyzed the association of YB-1 with drug resistance of TP53-mutated bladder cancer, including immunohistochemical analysis of YB-1, p-glycoprotein and p53 invivo as well as the function of YB-1 nuclear translocation and regulation of its translocation by p53 invitro. Additionally, we examined the association between the nuclear translocation of YB-1 and gemcitabine, a major anticancer-drug for bladder cancer, in cancer cell lines. Nuclear expression of YB-1 was correlated with the expression of p-glycoprotein and p53 in bladder cancer cases (p<0.05). Invitro, both introduction of TP53 and gemcitabine induced nuclear translocation of YB-1. These data indicate that YB-1 translocates to the nucleus coordinately with p53 expression and is involved in gemcitabine resistance in bladder cancer. Nuclear expression of YB-1 is important for resistance to chemotherapy including gemcitabine in TP53-mutated bladder cancer.

MiR-143 inhibits bladder cancer cell proliferation and enhances their sensitivity to gemcitabine by repressing IGF-1R signaling.

microRNAs (miRNAs) are a class of small RNAs that regulate gene expression. It has been demonstrated that aberrant miRNA expression is associated with cancer development and carcinogenesis. Altered miRNA expression has been suggested to occur in bladder cancer. In other cancer systems, studies have indicated that miR-143, as a tumor suppressor gene, plays essential roles in cancer progression. However, its role in bladder cancer has yet to be elucidated. In the present study, we observed that miR-143 expression was downregulated in human bladder cancer tissues and cells, and that its levels were negatively correlated with bladder cancer clinical stages. We further demonstrated that insulin-like growth factor-1 receptor (IGF-1R) is a functional target of miR-143. Their expression levels were inversely correlated in bladder cancer samples. Overexpression of miR-143 inhibited cell proliferation and promoted chemosensitivity of bladder cancer 5637 cells to gemcitabine. Consistently, small interfering RNA-mediated knockdown of IGF-1R phenocopied miR-143 overexpression. Notably, the expression of IGF-1R is a predictor of patient prognosis. Collectively, our findings indicate that miR-143 is a valuable biomarker for bladder cancer. The miR-143/IGF-1R axis is associated with bladder cancer drug resistance and patient survival.

Abstract B21: Chemoresistant bladder cancer cells induces epithelial mesenchymal transition

Abstract Although chemotherapeutic treatments are efficacious in a number of cancers, some cancer cells ultimately will become resistant to chemotherapy. It has been suggested that chronic chemotherapy-resistance is linked to the induction of epithelial mesenchymal transition (EMT). EMT is associated with increased tumor invasiveness, development of angiogenesis, and the development of drug resistance and is linked to more aggressive cancer. The objective of this study is to determine if a link exists between mitomycin C (MMC)-resistant RT-4 bladder cancer cells and the induction of EMT. EMT is a process where cells acquire molecular alterations characterized by loss of cell-cell adhesion, repression of E-cadherin expression, and increased cell mobility. Clinical studies have shown that as bladder cancer grade increases, tumors typically exhibit a decreased expression of E-cadherin, a cell-cell adhesion molecule. In addition, there is an increase in N-cadherin expression in muscle invasive bladder tumors. We have shown that MMC-resistant human RT-4 bladder cancer cells demonstrate a decrease in cell-cell adhesion, a higher invasion potential, and a higher CD44(+)/CD24(-) ratio (96.4%) compared to parental human RT-4 bladder cancer cells. In addition, the invasion capacity of MMC-resistant RT-4 bladder cancer cells was higher than that of parental cells. The MMC-resistant RT-4 bladder cancer cells expressed higher levels of N-cadherin and numerous apoptotic related proteins including pSTAT3, RAD17, Bcl-X and catalase. Using an exon array we showed that the MMC-resistant RT-4 bladder cancer cells up-regulate several EMT markers including vimentin (77 times), transforming growth factor -beta (27 times), and Zinc finger E-box-binding homeobox 1 (33 times) and down-regulate E-cadherin (71 times). In summary, in our MMC-resistant RT4 bladder cancer cells, EMT was activated, and there was an increase in apoptotic related proteins as well as an increase N-cadherin expression. Our data suggest a link between chemotherapy-resistant bladder cancer cells and EMT. Deactivating EMT and down-regulating apoptotic related proteins may offer a novel strategy for overcoming bladder cancer drug resistance. Citation Format: Jingchun Liu, Darryl T. Martin, Marcia A. Wheeler, Robert M. Weiss. Chemoresistant bladder cancer cells induces epithelial mesenchymal transition. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Drug Sensitivity and Resistance: Improving Cancer Therapy; Jun 18-21, 2014; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(4 Suppl): Abstract nr B21.

Abstract 4701: Acquisition of Oct-4 upregulation transactivates MDR1 and is associated with increased tumor recurrence in bladder cancer

Abstract Platinum-based drug like cisplatin is the standard first-line drug to treat patients with bladder cancer. However, tumors may recur and develop into multiple-drug resistant characteristics. The acquisition of resistance to conventional chemotherapy is a challenge in the treatment of bladder cancer relapse. Cancer stem cell (CSC) hypothesis has been an attractive theory. CSCs can resist therapeutic assaults, giving rise to multiple drug resistance and promotion of tumor relapse and metastasis. It has been shown that the fraction of cancer cells expressing MDR1 that functions as an energy-dependent drug efflux pump may be associated with Oct-4 expression. We have demonstrated that Oct-4 expression in bladder cancer predicts tumor progression. In the present study, we proposed that Oct-4 expression in bladder cancer increases MDR1 gene expression and thereby results in multiple drug resistance. We found a positive correlation between Oct-4 and MDR1 expression levels in clinical samples of bladder cancer. Furthermore, overexpression of Oct-4 increased MDR1 expression, which resulted in poor response to cisplatin in human bladder transitional cell carcinoma cells. Conversely, knockdown of Oct-4 reduced MDR1 expression and rendered cells hypersensitive to cisplatin. We also verified that Oct-4 transactivated the MDR1 gene promoter by binding to the Oct-4 response element (ORE). More importantly, Oct-4 and MDR1 gene expression could be induced by treatment with cisplatin, suggesting that Oct-4 is a member of the MDR1 enhanceosome. Our data can explain, in part, the high recurrence rate and drug resistance of bladder cancer. For clinical implication, we demonstrated that reduction of Oct-4 expression by all-trans retinoic acid, a derivative of vitamin A, improved sensitivity of bladder cancer cells to gemcitabine and cisplatin. In addition, we found that high expression levels of Oct-4 and MDR1 were associated with high tumor recurrence. Taken together, our results provide evidence that Oct-4 plays an important role in cisplatin-acquired resistance in bladder cancer. They also implicate Oct-4 as a therapeutic target. Note: This abstract was not presented at the meeting. Citation Format: Chia-Sing Lu, Ai-Li Shiau, Gia-Shing Shieh, Bing-Hua Su, Wu-Chou Su, Wen-Horng Yang, Chao-Liang Wu. Acquisition of Oct-4 upregulation transactivates MDR1 and is associated with increased tumor recurrence in bladder cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4701. doi:10.1158/1538-7445.AM2014-4701

Cancer stem-like cells contribute to cisplatin resistance and progression in bladder cancer

A variety of cancer stem-like cells (CSCs) have been shown to be responsible for cancer tumorigenicity, relapse and metastasis. Despite several reports demonstrating the presence of CSCs in human bladder cancer, their identities are still under debate, and few studies have examined their roles in cisplatin resistance and related tumor progression. In this study, a subpopulation of CSCs was enriched following cisplatin selection from the bladder cell line T24. The cisplatin-resistant T24 cells displayed a greater self-renewal capacity as demonstrated by higher levels of sphere formation and stem cell marker expression, contained a larger proportion of side population cells and exhibited higher tumorigenicity. They also possessed epithelial–mesenchymal transition characteristics. Furthermore, a strong correlation between the levels of Bmi1 and Nanog expression and the degree of malignancy of urothelial cell carcinomas tissues was observed. We provide the first direct evidence that CSC-like cells exist in the population of cisplatin-resistant bladder cancer cells and may play a role in the progression and drug resistance of bladder cancer.

VARIOUS FORMS OF MUTANT p53 CONFER SENSITIVITY TO CISPLATIN AND DOXORUBICIN IN BLADDER CANCER CELLS

The nature of p53 mutation has been reported to affect cellular responses to chemotherapy. We characterized the impact of p53 mutations on drug resistance in bladder cancer cells. Various human p53 mutants (V143A, V173L, H179Q, N247I and R273H) were introduced to the TCC-SUP bladder carcinoma cell line to establish stable transfectants. The expression of mutant p53 was demonstrated by reverse transcriptase-polymerase chain reaction and immunocytochemical analysis. The sensitivity to cisplatin and doxorubicin in these transfectants was determined by trypan blue exclusion. Cell death mediated by cisplatin and doxorubicin was characterized by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling analysis, Hoechst 33258 staining and annexin-V binding assay. The expression of all forms of mutant p53 protein except p53His273 enhanced sensitivity to cisplatin and doxorubicin. The chemosensitivity of p53His273 transfectants is similar to that of parental TCC-SUP and control transfectants. Cisplatin induced cell death undergoes apoptosis, as demonstrated by Hoechst staining, annexin-V assay and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling, respectively. In contrast, doxorubicin induced cell death probably occurs through a nonapoptotic pathway. These results indicated that the nature of p53 mutations may affect the cellular response to anticancer drugs and many forms of mutant p53 protein may enhance chemosensitivity through apoptotic or nonapoptotic pathways in bladder cancer cells.

Expression of basic fibroblast growth factor is associated with resistance to cisplatin in a human bladder cancer cell line

To clarify the role of basic fibroblast growth factor (FGF-2) in the drug resistance of bladder cancer, we transfected the FGF-2 gene into HT1376, an FGF-2 negative human bladder cancer cell line. The FGF-2-transfected cell lines exhibited three- to four-fold higher resistant potential to cisplatin than the vector-only transfected control cell lines in vitro. When cisplatin was injected intraperitoneally after s.c. implantation of HT1376 sublines into nude mice, FGF-2 transfectants formed tumors about twice as large as did controls. In contrast, there was no significant difference in either cell proliferation in vitro or tumor growth in vivo among these cell lines without cisplatin treatment. Furthermore, DNA degradation following cisplatin treatment was markedly suppressed in FGF-2 transfectants compared to control cells. These results suggest that the expression of the FGF-2 gene plays an important role in the acquisition of the cisplatin-resistant phenotype of bladder cancer, probably through the protection against cisplatin-induced apoptosis.

Antibacterial activity of adriamycin against bacillus Calmette-Guerin

Although intravesical instillation of bacillus Calmette-Guerin (BCG) or adriamycin (ADR) is an established and effective therapy for superficial bladder cancer, the current major problems are BCG-resistant and ADR-resistant bladder cancer and recurrence after the instillation therapy. Combination therapy with BCG and ADR might overcome the drug-resistance of bladder cancer. However, before combined used of BCG and ADR, it should be clarified whether ADR has bactericidal and bacteriostatic effects on BCG or not, since only alive BCG has a potential antitumor effect. In the current study, the in vitro antibacterial activity of ADR was assessed on BCG by the standard serial two-fold dilution method. When BCG was treated with ADR at 0.13-125 mu g/ml for two hours, ADR had no effect on the viability and the growth of BCG. However, ADR at 250-1,000 mu g/ml had a bactericidal effect on BCG. Epirubicin (EPI) at 0.13-15.6 mu g/ml did not affect the viability and the growth of BCG, however, EPI at 31.3-1,000 mu g/ml had a bactericidal activity. Pirarubicin (THP) at 125-1,000 mu g/ml also had a bactericidal activity. The minimal inhibitory concentrations of ADR, EPI and THP were 250, 250 and 125 mu g/ml, respectively. This study demonstrates that ADR at high concentrations had bactericidal and bacteriostatic effects on BCG. These findings suggest that combination treatment with BCG and low dose ADR could be used and overcome the resistance of bladder cancer to BCG and ADR. The possible clinical implications of the combined use of BCG and ADR are discussed.