Pyrimidine-thioindole inhibits gastric cancer cell proliferation via up-regulation of expression of tumor suppressor miR-145

Purpose: To investigate the effect of pyrimidine-thioindole on gastric cancer proliferation and the underlying mechanism of action. Methods: Cell viability and apoptosis were determined using MTT assay and Annexin V/P1 assay, respectively. Reverse transcription-polymerase chain reaction (RT-PCR) was used for the determination of expression levels of miR-145, while protein expression levels were assayed by western blotting. Results: Pyrimidine-thioindole treatment significantly inhibited the proliferation of AGS and SNU-5 cells (p < 0.05), but had no effect on the viability of GES-1 cells. Exposure to pyrimidine-thioindole at doses of 8 and 10 mu M significantly enhanced the apoptosis of AGS and SNU-5 cells (p < 0.05). Pyrimidine-thioindole exposure markedly increased the proportions of AGS and SNU-5 cells in G1 phase (p < 0.05). In AGS and SNU-5 cell lines, pyrimidine-thioindole exposure at doses of 8 and 10 mu M significantly upregulated the expression of miR-145, with higher enhancement of miR-145 expression in AGS cells than in SNU-5 cells. Moreover, pyrimidine-thioindole downregulated the expressions of MMP-2, MMP-9, c-Myc, p-PI3K and p-AKT in AGS and SNU-5 cells. Pyrimidine-thioindole treatment enhanced the expression of p21 in AGS and SNU-5 cells, relative to untreated cells (p < 0.05). Conclusion: These results suggest that pyrimidine-thioindole activates apoptotic signaling pathway, leading to reduction in cell proliferation and arrest of cell cycle. Moreover, it de-activates PI3K/AKT pathway and promotes miR-145 expression in AGS and SNU-5 cells. Thus, pyrimidine-thioindole has therapeutic significance for the management of gastric cancer.