Department of General Surgery, The First Affiliated Hospital of Jinzhou Medical University, No. 2, The Fifth Section of Renmin Street, Jinzhou, Liaoning Province, China.
Department of Obstetrics and Gynecology, The First Affiliated Hospital of Jinzhou Medical University, No. 2, The Fifth Section of Renmin Street, Jinzhou, Liaoning Province, China.
Hum Cell. 2022 Sep;35(5):1535-1546. doi: 10.1007/s13577-022-00759-5. Epub 2022 Jul 30.
Transmembrane protein 97 (TMEM97) is a conserved integral membrane protein highly expressed in various human cancers, including colorectal cancer (CRC), and it exhibits pro-tumor roles in breast cancer, gastric cancer, and glioma. However, whether TMEM97 participates in CRC progression is not fully understood. The expression of mRNA and protein was evaluated by real-time qPCR, western blotting, immunofluorescent, and immunohistochemical staining. TMEM97 functions in cell proliferation, apoptosis, migration, and invasion were assessed by CCK-8, flow cytometry, and transwell assays. The roles of TMEM97 in CRC cells in vivo was investigated using a subcutaneous xenograft model. The transcriptional regulation of TMEM97 was explored by luciferase reporter and ChIP assays. The silencing of TMEM97 inhibited migration and invasion of CRC cells in vitro and led to suppressed growth and enhanced apoptosis in CRC cells and xenografts, whereas overexpression of TMEM97 displayed opposite effects. Mechanistically, TMEM97 knockdown caused a reduction of the proliferating marker PCNA and an increase of pro-apoptotic proteins (cleaved caspase 8/3/7 and cleaved PARP) in CRC cells. TMEM97 also positively regulated the β-catenin signaling pathway in CRC cells and xenografts by modulating the phosphorylated-GSK-3β and active (non-phospho) β-catenin levels. Interestingly, YY1, a well-recognized oncogenic transcription factor, was identified to bind to the TMEM97 promoter and enhance its transcriptional activity, and silencing of TMEM97 abolished YY1-mediated pro-tumor effects on CRC cells. Our results suggest that TMEM97 is transcriptionally activated by YY1 and promotes CRC progression via the GSK-3β/β-catenin signaling pathway, providing that TMEM97 might be a novel therapeutic target for preventing CRC development.
跨膜蛋白 97（TMEM97）是一种保守的整合膜蛋白，在包括结直肠癌（CRC）在内的各种人类癌症中高度表达，并且在乳腺癌、胃癌和神经胶质瘤中表现出促进肿瘤的作用。然而，TMEM97 是否参与 CRC 的进展尚不完全清楚。通过实时 qPCR、western blot、免疫荧光和免疫组织化学染色评估 mRNA 和蛋白的表达。通过 CCK-8、流式细胞术和 Transwell 测定评估 TMEM97 在细胞增殖、凋亡、迁移和侵袭中的作用。通过皮下异种移植模型研究 TMEM97 在 CRC 细胞中的体内作用。通过荧光素酶报告和 ChIP 测定探索 TMEM97 的转录调控。沉默 TMEM97 抑制 CRC 细胞的迁移和侵袭，导致 CRC 细胞和异种移植物的生长受到抑制，凋亡增强，而过表达 TMEM97 则显示出相反的效果。机制上，TMEM97 敲低导致 CRC 细胞中增殖标志物 PCNA 的减少和促凋亡蛋白（裂解的 caspase 8/3/7 和裂解的 PARP）的增加。TMEM97 还通过调节磷酸化-GSK-3β 和活性（非磷酸化）β-catenin 水平，在 CRC 细胞和异种移植物中正向调节 β-catenin 信号通路。有趣的是，YY1，一种公认的致癌转录因子，被鉴定为与 TMEM97 启动子结合并增强其转录活性，沉默 TMEM97 消除了 YY1 对 CRC 细胞的促肿瘤作用。我们的研究结果表明，TMEM97 被 YY1 转录激活，并通过 GSK-3β/β-catenin 信号通路促进 CRC 的进展，这表明 TMEM97 可能成为预防 CRC 发展的新的治疗靶点。
