Relationship Between HSP70 and ERBB2 Expression in Breast Cancer Cell Lines Regarding Drug Resistance.

Background: Heat shock protein 70 (HSP70) is known to be downstream of human epidermal growth factor receptor-2 (ERBB2), but little is known regarding the relationship between HSP70 and drug resistance mediated by ERBB2 in breast cancer. Materials and Methods: After infecting breast cancer cells with lentivirus-mediated Lenti-ShHSP70 and Lenti-ShERBB2, we examined the expression of HSP70 and ERBB2 by real-time polymerase chain reaction and western blotting. Results: Compared to the control groups, mRNA expression of HSP70 was decreased in lentivirus-infected, and western blotting indicated a concordant reduction of HSP70 protein. On the other hand, ERBB2 was significantly down-regulated by HSP70 silencing in SK-BR-3 cells at both the mRNA and protein levels. Expression of HSP70 in transfected cells was also reduced by Lenti-ShERBB2. CCK8 viability assay indicated that inhibition of HSP70 increased the sensitivity of SK-BR-3 cells to fluorouracil treatment. Conclusion: HSP70 affects ERBB2 and ERBB2-mediated drug-resistance in breast cancer cells.