Study on the effects of c-erbB-2-specific antisense oligonucleotides on c-erbB-2 overexpressing breast cancer cells

10724 Background: Overexpression of c-erbB2 oncoprotein was always correlated with bad prognostic. In this study, we will research on the effects of c-erbB-2-specific antisense oligonucleotides (ODNs) on c-erbB-2 expression, cell proliferation and apoptosis of c-erbB-2 over-expressing breast cancer TM40D cells, and to further study the effects of c-erbB-2-specific oligonucleotides on breast cancer xenografts in Balb/c mice. Methods: Balb/c mouse derived breast cancer cell line TM40D was incubated with liposome-mediated ODNs for 4 h and cultured for another 72 h, then the effects of ODNs on c-erbB-2 expression, cell proliferation and activation of apoptosis were examined by western blot, MTT assay and flow cytometry. Twenty-six mice with breast cancer xenografts were randomized into three groups—9 in control group, 9 in lipsome group and 8 in therapy group, which were injected hypodermically with 0.1 ml serum-free RPMI-1640 culture-medium, lipsome (10 ug/ml) solution, and the mixture of lipsome solution (10 ug/ml) and anti-sense ODN (1 uM) weekly for consecutive 6 weeks, respectively. After the therapy, the incidence of skin ulcer was recorded, the lumps were removed and weighted, and part of them were used for Flow Cytometry. Results: Western Blotting showed treatment of TM40D cells with c-erbB-2-specific antisense ODNs resulted in inhibition of c-erbB-2 expression. The effects of antisense ODNs on c-erbB-2 protein levels correlated with their effects on cell proliferation. MTT Assay showed antisense ODNs inhibited cell growth by about 50%. Flow cytometry analysis revealed that antisense ODNs increased cell apoptosis by38.5%, compared with cultured cells group 9.13% and liposome group 9.29%. The weight of lumps in the therapy group was significantly lower than that of in the other two groups. Flow Cytometry showed that in the therapy group the ratio of G0/G1 cells in cell cycles was 87.18%, which is higher compared with the other two and proliferation index was lower. Conclusions: Antisense ODNs reduced c-erbB-2 expression, inhibited cell proliferation and induced cell apoptosis. Anti-sense ODNs can inhibit the growth of c-erbB2-overexpressing breast cancer xenogarfts in Balb/c mice. No significant financial relationships to disclose.