M-Phase Phosphoprotein 9 upregulation associates with poor prognosis and activates mTOR signaling in gastric cancer.

The function of M-Phase Phosphoprotein 9 (MPHOSPH9) has not been investigated in gastric cancer yet. In the present study, the public cancer databases Oncomine and TCGA were analyzed, and MPHOSPH9 was found upregulated in gastric cancer tumor tissues. Immunohistochemistry (IHC) was also carried out to further confirm the results, and IHC analysis showed MPHOSPH9 was elevated in tumor tissues compared with the paracancerous tissues. QRT-PCR analysis also revealed that MPHOSPH9 mRNA was upregulated in gastric cancer cell lines. In addition, Kaplan-Meier estimates showed gastric cancer patients with high MPHOSPH9 level predicted a poor prognosis. Then, Western blot and CCK-8 assay showed overexpressed MPHOSPH9 enhanced gastric cancer cell proliferation, but MPHOSPH9 knockdown suppressed gastric cancer cell proliferation. Additionally, Western blot showed that MPHOSPH9 regulated the activation of mTOR, and overexpressed MPHOSPH9 reduced the inhibitory effects of mTOR inhibitors on cell survival in gastric cancer cells. Taken together, our results suggested that MPHOSPH9 .could be an oncogene in gastric cancer by regulating mTOR signaling.