RESUMO
OBJECTIVE: To explore the inhibitory effects on glucosylceramide synthase (GCS) expression and drug sensitivity in breast cancer cells by transfecting artificial microRNA targeting GCS. METHODS: Two microRNA expression vectors targeting GCS were constructed and transfected into MCF-7/ADR cells via Lipofectamine 2000. The levels of GCS mRNA and protein were measured by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot respectively. Methyl thiazolyl tetrazolium (MTT) assay was used to assess the chemosensitivity of MCF-7/ADR cells to adriamycin (ADM) and vincristine. RESULTS: After transfection of two microRNA expression vectors, the expression of GCSmRNA in MCF-7/ADR cells was 0.098 ± 0.005 and 0.143 ± 0.007 respectively. Compared with the control cells (0.875 ± 0.008), the difference was significant (P < 0.01). The expression of GCS protein (0.127 ± 0.004, 0.165 ± 0.008) in MCF-7/ADR cells was lower than that in the control cells (0.765 ± 0.007; P < 0.01). Furthermore, in comparison with the control cells, the resistance factor to adriamycin significantly dropped to 4.06 and 6.06 while the drug resistance to vincristine decreased to 8.30 and 12.67 respectively (P < 0.01). CONCLUSION: Artificial microRNA targeting GCS inhibits the GCS expression and restores significantly the sensitivity of breast cancer cells to anticancer drugs. These findings may provide a novel strategy of enhancing the chemotherapy sensitivity of breast cancer.