Conclusion
he current study demonstrated that the downregulation of Siva-1, which functions as a regulator of MDR1 and MRP1 gene expression in gastric cancer cells by inhibiting PCBP1/Akt/NF-κB signaling pathway expression, enhanced the sensitivity of gastric cancer cells to certain chemotherapies.
Methods
A vincristine-resistant MKN-28/VCR gastric cancer cell line with stably downregulated Siva-1 was established. The effect of Siva-1 downregulation on chemotherapeutic drug resistance was assessed by measuring the IC50 and pump rate of doxorubicin. Proliferation, apoptosis of cells, and cell cycle were detected via colony formation assay and flow cytometry, respectively. Additionally, migration and invasion of cells was detected via wound healing and transwell assays. Moreover, we determined in vivo effects of LV-Siva-1-RNAi on tumor size, and apoptotic cells in tumor tissues were detected using TUNEL and hematoxylin and eosin staining.
Results
Siva-1 downregulation reduced the pump rate of doxorubicin and enhanced the response to drug treatment. Siva-1 negatively regulated proliferation and promoted apoptosis of cells by potentiality G2-M phase arresting. Inhibition of Siva-1 expression in MKN-28/VCR cells significantly weakened wound healing ability and decreased invasion ability. Poly(C)-binding protein 1 (PCBP1) was identified as a Siva-1-interacting protein in yeast two-hybrid screening. Semiquantitative RT-PCR and western blotting revealed that Siva-1 downregulation could inhibit expression of PCBP1, Akt, and NF-κB and eventually decrease the expression of MDR1 and MRP1.