Sun Guangli, Li Zheng, He Zhongyuan, Wang Weizhi, Wang Sen, Zhang Xing, Cao Jiacheng, Xu Penghui, Wang Haixiao, Huang Xiaoxu, Xia Yiwen, Lv Jialun, Xuan Zhe, Jiang Tianlu, Fang Lang, Yang Jing, Zhang Diancai, Xu Hao, Xu Zekuan
Department of General Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu province, China.
Collaborative Innovation Center for Cancer Personalized Medicine, Nanjing Medical University, Nanjing, Jiangsu province, China.
J Exp Clin Cancer Res. 2020 Nov 17;39(1):246. doi: 10.1186/s13046-020-01758-w.
Cisplatin (CDDP) is the first-line chemotherapy for gastric cancer (GC). The poor prognosis of GC patients is partially due to the development of CDDP resistance. Circular RNAs (circRNAs) are a subclass of noncoding RNAs that function as microRNA (miRNA) sponges. The role of circRNAs in CDDP resistance in GC has not been evaluated.
RNA sequencing was used to identify the differentially expressed circRNAs between CDDP-resistant and CDDP-sensitive GC cells. qRT-PCR was used to detect the expression of circMCTP2 in GC tissues. The effects of circMCTP2 on CDDP resistance were investigated in vitro and in vivo. Pull-down assays and luciferase reporter assays were performed to confirm the interactions among circMCTP2, miR-99a-5p, and myotubularin-related protein 3 (MTMR3). The protein expression levels of MTMR3 were detected by western blotting. Autophagy was evaluated by confocal microscopy and transmission electron microscopy (TEM).
CircMCTP2 was downregulated in CDDP-resistant GC cells and tissues compared to CDDP-sensitive GC cells and tissues. A high level of circMCTP2 was found to be a favorable factor for the prognosis of patients with GC. CircMCTP2 inhibited proliferation while promoting apoptosis of CDDP-resistant GC cells in response to CDDP treatment. CircMCTP2 was also found to reduce autophagy in CDDP-resistant GC cells. MiR-99a-5p was verified to be sponged by circMCTP2. Inhibition of miR-99a-5p could sensitize GC cells to CDDP. MTMR3 was confirmed to be a direct target of miR-99a-5p. Knockdown of MTMR3 reversed the effects of circMCTP2 on the proliferation, apoptosis and autophagy of CDDP-resistant GC cells. CircMCTP2 was also confirmed to inhibit CDDP resistance in vivo in a nude mouse xenograft model.
CircMCTP2 sensitizes GC to CDDP through the upregulation of MTMR3 by sponging miR-99a-5p. Overexpression of CircMCTP2 could be a new therapeutic strategy for counteracting CDDP resistance in GC.
顺铂（CDDP）是胃癌（GC）的一线化疗药物。GC患者预后较差部分归因于顺铂耐药的产生。环状RNA（circRNAs）是非编码RNA的一个亚类，可作为微小RNA（miRNA）的海绵。circRNAs在GC顺铂耐药中的作用尚未得到评估。
采用RNA测序鉴定顺铂耐药和敏感的GC细胞之间差异表达的circRNAs。qRT-PCR用于检测GC组织中circMCTP2的表达。在体外和体内研究circMCTP2对顺铂耐药的影响。进行下拉试验和荧光素酶报告基因试验以证实circMCTP2、miR-99a-5p和肌管蛋白相关蛋白3（MTMR3）之间的相互作用。通过蛋白质免疫印迹法检测MTMR3的蛋白表达水平。通过共聚焦显微镜和透射电子显微镜（TEM）评估自噬。
与顺铂敏感的GC细胞和组织相比，circMCTP2在顺铂耐药的GC细胞和组织中表达下调。发现高水平的circMCTP2是GC患者预后的有利因素。circMCTP2抑制顺铂耐药GC细胞的增殖，同时促进其对顺铂治疗的凋亡。还发现circMCTP2可减少顺铂耐药GC细胞中的自噬。已证实miR-99a-5p被circMCTP2吸附。抑制miR-99a-5p可使GC细胞对顺铂敏感。已证实MTMR3是miR-99a-5p的直接靶标。敲低MTMR3可逆转circMCTP2对顺铂耐药GC细胞增殖、凋亡和自噬的影响。在裸鼠异种移植模型中也证实circMCTP2在体内可抑制顺铂耐药。
circMCTP2通过吸附miR-99a-5p上调MTMR3使GC对顺铂敏感。CircMCTP2的过表达可能是对抗GC顺铂耐药的一种新的治疗策略。
