Effect of nucleophosmin on breast cancer resistance in MCF-7/MTX cells / 中国药学杂志

ABSTRACT

OBJECTIVE: To investigate the mechanism of nucleophosmin (NPM) in the formation of breast cancer drug resistance. METHODS: The methotrexate-resistant breast cancer cells (MCF-7 /MTX) was established by escalating the concentrations of methotrexate to drug-sensitive MCF-7 cells (MCF-7/S). The cells viability of MCF-7/MTX was detected by MTT test, cell growth curve was drawn and doubling time was calculated. The cell morphology and ultrastructure were observed using optical and transmission electron microscopy. The expression of NPM and factors related to drug resistance were tested by Real-time PCR and Western blot assay. Then the NPM level was attenuated by RNA interfering technology, and the resistance mechanism was explored in MCF-7/MTX cells. RESULTS The MCF-7/MTX cell line was successfully established and resistance factor was 64. The resistant cells has spindle shaped morphology and tended to grow slowly, and the variations appeared in the internal structure of cells. MCF-7/MTX cells possessed cross-resistance to various chemotherapeutic drugs. The expressions of NPM and multidrug-resistant factors P-gp, MRP1, BCRP were up-regulated in the resistant cells. Further, the overexpression of NPM activated PI3K/Akt signaling pathway and inhibited downstream apoptotic factors. Then knockdown of NPM by siRNA significantly decreased the drug resistance of MCF-7/MTX cells, suppressed PI3K/Akt pathway and promoted the downstream cells apoptosis. CONCLUSION The high expression of NPM has an important role in the formation of breast cancer drug resistance, and it is expected to be a novel molecular target for breast cancer treatment in clinical.