ABSTRACT
Overexpression of cytokine-induced apoptosis inhibitor 1 (CIAPIN1) contributes to multidrug resistance (MDR) in breast cancer. This study aimed to evaluate the potential of CIAPIN1 gene silencing by RNA interference (RNAi) as a treatment for drug-resistant breast cancer and to investigate the effect of CIAPIN1 on the drug resistance of breast cancer in vivo. We used lentivirus-vector-based RNAi to knock down CIAPIN1 in nude mice bearing MDR breast cancer tumors and found that lentivirus-vector-mediated silencing of CIAPIN1 could efficiently and significantly inhibit tumor growth when combined with chemotherapy in vivo. Furthermore, Western blot analysis showed that both CIAPIN1 and P-glycoprotein expression were efficiently downregulated, and P53 was upregulated, after RNAi. Therefore, we concluded that lentivirus-vector-mediated RNAi targeting of CIAPIN1 is a potential approach to reverse MDR of breast cancer. In addition, CIAPIN1 may participate in MDR of breast cancer by regulating P-glycoprotein and P53 expression.
Subject(s)
Animals , Female , Humans , Antibiotics, Antineoplastic/therapeutic use , Breast Neoplasms/drug therapy , Doxorubicin/therapeutic use , Drug Resistance, Neoplasm/genetics , Gene Silencing , Intracellular Signaling Peptides and Proteins/genetics , Blotting, Western , Breast Neoplasms/genetics , Carcinoma/drug therapy , Carcinoma/genetics , Disease Models, Animal , Genes, MDR , Genetic Vectors/genetics , Growth Inhibitors/genetics , Intracellular Signaling Peptides and Proteins/metabolism , Lentivirus/genetics , Mice, Inbred BALB C , Mice, Nude , ATP Binding Cassette Transporter, Subfamily B, Member 1/drug effects , RNA Interference , RNA, Small Interfering/genetics , /drug effectsABSTRACT
MDR1 promoter has been shown to contain heat shock elements (HSE), and it has been reported that FM3A/M and P388/M MDR cells show a constitutively activated heat shock factor (HSF), suggesting that HSF might be an important target for reversing the multidrug resistance. Therefore, it was examined whether quercetin, which has been shown to interfere with the formation of the complex between HSE and HSF, and to downregulate the level of HSF1, can sensitize MDR cells against anticancer drugs by inhibition of HSF DNA-binding activity. In this study, quercetin appeared to inhibit the constitutive HSF DNA-binding activity and the sodium arsenite-induced HSF DNA-binding activity in the MDR cells. The basal and sodium arsenite-induced MDRCAT activities were remarkably suppressed by the treatment of quercetin. These results were well consistent with the finding that the treatment of quercetin decreased the expression level of P-gp, MDR1 gene product, in dose-dependent manner, and markedly increased the sensitivity of MDR cells to vincristine or vinblastine. These results suggest that quercetin can decrease the expression of P-gp via inhibition of HSF DNA-binding activity, and might be useful as a chemosensitizer in MDR cells.