Feng Xiaojie, Bai Xupeng, Ni Jie, Wasinger Valerie C, Beretov Julia, Zhu Ying, Graham Peter, Li Yong
Department of Gynaecological Oncology, Henan Cancer Hospital, Zhengzhou, China.
Cancer Care Centre, St. George Hospital, Kogarah, NSW, Australia.
Front Oncol. 2019 Jun 27;9:557. doi: 10.3389/fonc.2019.00557. eCollection 2019.
Chemoresistance is a major challenge in epithelial ovarian cancer (EOC) treatment. Chromatin target of protein arginine methyltransferase (CHTOP) was identified as a potential biomarker in chemoresistant EOC cell lines using label-free LC-MS/MS quantitative proteomics. Thus, the aim of this study is to investigate the role of CHTOP in chemoresistant EOC and the underlying mechanism. The expression of CHTOP in human ovarian cancer cells and tissues was detected using immunofluorescence (IF), western blot (WB), and immunohistochemistry (IHC), respectively. Flow cytometry and TUNEL assay were employed to detect the effect of CHTOP knockdown (KD) in chemoresistant EOC cell apoptosis, while colony and sphere formation assays were used to evaluate its effect on cell stemness. The association of CHTOP with cell metastasis was determined using Matrigel invasion and wound-healing assays. The higher level expression of CHTOP protein was found in chemoresistant EOC cells as compared to their sensitive parental cells or normal epithelial ovarian cells. Results from IHC and bioinformatic analysis showed CHTOP was highly expressed in human ovarian cancer tissues and associated with a poor progression-free survival in patients. In addition, CHTOP KD significantly enhanced cisplatin-induced apoptosis, reduced the stemness of chemoresistant EOC cells, and decreased their metastatic potential. Our findings suggest that CHTOP is associated with apoptosis, stemness, and metastasis in chemoresistant EOC cells and might be a promising target to overcome chemoresistance in EOC treatment.
化疗耐药是上皮性卵巢癌（EOC）治疗中的一个主要挑战。利用无标记液相色谱-质谱联用（LC-MS/MS）定量蛋白质组学技术，确定蛋白质精氨酸甲基转移酶的染色质靶点（CHTOP）为化疗耐药EOC细胞系中的一种潜在生物标志物。因此，本研究的目的是探讨CHTOP在化疗耐药EOC中的作用及其潜在机制。分别采用免疫荧光（IF）、蛋白质免疫印迹（WB）和免疫组织化学（IHC）检测人卵巢癌细胞和组织中CHTOP的表达。采用流式细胞术和TUNEL法检测CHTOP基因敲低（KD）对化疗耐药EOC细胞凋亡的影响，同时采用集落形成和球体形成试验评估其对细胞干性的影响。采用基质胶侵袭试验和伤口愈合试验确定CHTOP与细胞转移的关系。与敏感的亲本细胞或正常上皮性卵巢细胞相比，化疗耐药EOC细胞中CHTOP蛋白的表达水平更高。免疫组织化学和生物信息学分析结果显示，CHTOP在人卵巢癌组织中高表达，且与患者无进展生存期较差相关。此外，CHTOP基因敲低显著增强顺铂诱导的凋亡，降低化疗耐药EOC细胞的干性，并降低其转移潜能。我们的研究结果表明，CHTOP与化疗耐药EOC细胞的凋亡、干性和转移有关，可能是克服EOC治疗中化疗耐药的一个有前景的靶点。
