Objectives To detect the expression of Melanoma nuclear protein 18 (Mel-18) in endometrial carcinoma (EC) and evaluate the biological effects of Mel-18 on the proliferation, immigration and cell cycle of EC cells.

Methods Immunohistochemistry (IHC), Western blotting and RT-qPCR assays were used to examine the expression of Mel-18 in EC. Adenovirus and siRNA were used to regulate Mel-18 gene levels in cells. The MTT dye solution and colony formation assay were used to detect the cell proliferation activity. Transwell migration Assay was used to detect the cell immigration ability. The cell cycle was detected by flow cytometry. Western blotting was used to detect the related proteins expression in PI3K/AKT/mTOR pathway.

Results Mel-18 mRNA and protein were both highly expressed in EC (P < 0.05). The Mel-18 mRNA and protein expression were both significantly increased by transducted with adenovirus encoding Mel-18 cDNA (P <0.05). Meanwhile, The Mel-18 protein and mRNA levels were significantly reduced by transfected with siRNA-Mel-18 (P <0.05). Up-regulation of Mel-18 was significantly promoted the cell viability, clonality and migration capacity (P <0.05). The percentage of cells at S + G2/M phase was significantly increased in Mel-18–overexpressing cells (P < 0.05). We also explored the potential mechanism of Mel-18 in EC cell lines. Overexpression of Mel-18 activated the PI3K/AKT/mTOR pathway, the expression of PI3K p85α, p-AKT, p-mTOR, c-myc, cyclin D1 and bcl-2 proteins were significantly increased, but bax protein was decreased.

Conclusions Mel-18 was highly expressed in EC and promoted cell proliferation, migration and positively regulated cell cycle progression via PI3K/AKT/mTOR pathway.