[Hypoxia inducible factor-1α deSUMOylation reduces the stemness maintenance ability of endometrial cancer stem cell and increases its chemosensitivity].

Objective To reduce the stemness maintenance ability of endometrial cancer stem cell and increase its sensitivity to chemotherapy by inducing hypoxia inducible factor 1α (HIF-1α) protein deSUMOylation. Methods Lentiviral plasmid mediated ubiquitin carrier protein 9 (Ubc9) gene silencing was transgened into KLE endometrial carcinoma cells. The expression of Ubc9, small ubiquitin-related modifier 1(SUMO1) and HIF-1α protein was detected by Western blotting. Then tumor stem cells clones were cultured in 96 well plates, and these clone balls diameter were calculated. Cell cycles were determined by flow cytometry. MTT cytotoxicity assay and flow cytometry method were used to test sensitivity of cisplatin to endometrial cancer stem cell. Results The results of Western blotting showed that Ubc9 gene was silenced well, and the covalent binding state of SUMO-1 and HIF-1α protein levels were significantly decreased (P<0.05). Ubc9 gene silencing in endometrial cancer cells reduced clone formation rate by (31.61±5.29)% down to (11.42±3.07)%, while the cell cycle shift from G1 to G2. IC50 of cisplatin decreased from 44.37 mg/L to 7.39 mg/L, and the rate of cell apoptosis by (41.59±5.37)% down to (26.22±4.03)%. Conclusion The stemness maintenance ability of endometrial cancer stem cell can be reduced through deSUMOylation of HIF-1α protein by silencing Ubc9 gene expression, and their sensitivity to chemotherapy be enhanced, which provides a new reference for future gene therapy of endometrial carcinoma. Key words: Endometrial carcinoma; Tumor stem cells; Small ubiquitin related modifier protein; Cisplatin; Hypoxia inducible factor -1 alpha