Antisense oligodeoxynucleotide targeting HER2 mRNA sensitized docetaxel in breast cancer treatment.

Context: Human epidermal growth factor receptor 2 (HER2) is one of the oncogenes closely associated with the development and prognosis of breast carcinoma. Down-regulation of HER2 mRNA by antisense oligodeoxynucleotide (ASO) HER2 has been suggested to be a feasible treatment for patients with breast carcinoma. Objective: The antitumor effects of ASO HA6722 were investigated in vitro and in vivo. Materials and methods: In this study, SK-BR-3, a HER2-overexpressing breast carcinoma cell line, was used as the model for in vitro experiments. Inhibitory effects of the ASO HA6722 were detected by methyl-thiazoldiphenyl tetrazolium (MTT) assay. Meanwhile, HER2 mRNA levels were monitored by reverse transcription polymerase chain reaction (RT-PCR). The in vivo antitumor effects were evaluated in nude mice xenograft model. Results: Our results showed that HA6722 alone could inhibit the growth of SK-BR-3 cells in a dose-dependent manner with the IC(50) value of 41.8 +/- 8.1 nM. In addition, the antitumor effect of docetaxel (TXT) could be sensitized by low dose of HA6722 both in vitro and in vivo, suggesting that ASO HA6722 could inhibit the growth of breast cancer cells and enhance the cytotoxic effects of TXT. Discussion and conclusion: The combination treatment of TXT and HA6722 could be a more effective approach for breast cancer treatment. The future study should focus on the antitumor effect in other models.