UBE2S promotes the progression and Olaparib resistance of ovarian cancer through Wnt/β-catenin signaling pathway

Background: Ovarian cancer is the most lethal gynecologic malignancy worldwide. Olaparib, an inhibitor of poly (ADP-ribose) polymerase (PARP), is becoming widely used in ovarian cancer treatment. The overall survival of ovarian cancer has not been significantly changed over the past decades and ovarian cancer has become increasingly resistant to the Olaparib. Ubiquitin-conjugating enzyme E2S (UBE2S) has been proved to promote malignant behaviors in many cancers. However, the function of UBE2S in the development and Olaparib resistance of ovarian cancer are unclear.

Materials and methods: In this study, we detected the expression of UBE2S in normal fallopian tube (FT) and HGSOC tissues. A2780 and SKOV3 cells were stably transfected with PCMV-UBE2S, PCMV-UBE2S-C95S, UBE2S shRNAs, and negative controls. The CCK8 assay and clonogenic assay were conducted to analyze ovarian cancer proliferation and Olaparib resistance. The transwell assay was performed to determine the migration and invasion of ovarian cancer cells. The relative protein levels of the Wnt/β-catenin signaling pathway were tested using western blot. The ovarian cancer cells were treated with XAV-939 to investigate the role of Wnt/β-catenin signaling pathway in Olaparib resistance. Moreover, we repeated some above procedures in the xenograft model.

Results: The results demonstrated that UBE2S was highly upregulated in HGSOC and that high UBE2S expression was correlated with poor outcomes in HGSOC. UBE2S promoted ovarian cancer proliferation and drived the migration and invasion of ovarian cancer cells. UBE2S activated the Wnt/β-catenin signaling pathway in ovarian cancer resulting in Olaparib resistance in vitro and in vivo. Furthermore, UBE2S enhanced the proliferation and Olaparib resistance of ovarian cancer in its enzymatic activity dependent manner.

Conclusions: These data suggest a possible molecular mechanism of proliferation and metastasis of ovarian cancer and highlight the potential role of UBE2S as a therapeutic target in ovarian cancer.