Department of Respiratory Medicine, Seventh People's Hospital of Shanghai University of TCM, Shanghai 200137, China.
Department of General Practice, Changhai Hospital, Naval Medical University (Second Military Medical University), Shanghai 200433, China.
Contrast Media Mol Imaging. 2022 Jul 16;2022:1087622. doi: 10.1155/2022/1087622. eCollection 2022.
circ_SFMBT2 was reported to facilitate malignant progression in various cancers, but its function in non-small-cell lung cancer (NSCLC) has not been fully uncovered. This study aimed to investigate the effects of N6-methyladenosine (m6A) methylation of circ_SFMBT2 (circ_0017628) on non-small-cell lung cancer (NSCLC) and its underlying mechanisms.
Paired tumor and noncancerous tissues from NSCLC patients were surgically collected from January 2020 to March 2021 in our hospital. The levels of circ_SFMBT2 and LATS2 in NSCLC and human bronchial epithelial cells were assayed with qRT-PCR. Overexpression or silencing of circ_SFMBT2, LATS2, or YTHDF2 was performed in the NSCLC cells. CCK-8, colony-forming, and transwell assays were performed to analyze cell proliferation, viability, and migration, respectively. Meanwhile, the expression of MMP-9, E-cadherin, vimentin, and the Hippo/YAP pathway components was examined by western blotting. The m6A enrichment in circ_SFMBT2 was verified using methylated RNA immunoprecipitation, and interaction between circ_SFMBT2 and YTHDF2 was assessed by RNA pull-down and immunoprecipitation assays.
Both circ_SFMBT2 and LATS2 were lowly expressed in NSCLC cells and tissues. A positive correlation of circ_SFMBT2 with LATS2 was identified, and circ_SFMBT2 was localized predominantly in the cytoplasm. circ_SFMBT2 overexpression negatively regulated cell proliferation, viability, migration, and epithelial-mesenchymal transition while promoting the Hippo/YAP pathway activation. Notably, knockdown of LATS2 effectively abrogated the inhibitory effects of circ_SFMBT2 overexpression on NSCLC cell malignancies. Besides, m6A was specifically enriched in circ_SFMBT2, and circ_SFMBT2 could bind to YTHDF2. Silencing of YTHDF2 led to an increase in circ_SFMBT2 expression while inhibiting the malignancy of cancer cells.
Our results showed that YTHDF2 could facilitate NSCLC cell proliferation and metastasis via the Hippo/YAP pathway activation by mediating circ_SFMBT2 degradation.
circ_SFMBT2 已被报道可促进多种癌症的恶性进展，但在非小细胞肺癌（NSCLC）中的作用尚未完全揭示。本研究旨在探讨 circ_SFMBT2（circ_0017628）的 N6-甲基腺苷（m6A）甲基化对非小细胞肺癌（NSCLC）的影响及其潜在机制。
我们于 2020 年 1 月至 2021 年 3 月从我院接受手术的 NSCLC 患者的配对肿瘤和非癌组织中收集了组织样本。使用 qRT-PCR 测定 NSCLC 组织和人支气管上皮细胞中 circ_SFMBT2 和 LATS2 的水平。在 NSCLC 细胞中过表达或沉默 circ_SFMBT2、LATS2 或 YTHDF2。通过 CCK-8、集落形成和 Transwell 测定分别分析细胞增殖、活力和迁移。同时，通过 Western blot 检测 MMP-9、E-钙黏蛋白、波形蛋白和 Hippo/YAP 通路成分的表达。使用甲基化 RNA 免疫沉淀验证 circ_SFMBT2 中的 m6A 富集，通过 RNA 下拉和免疫沉淀测定评估 circ_SFMBT2 与 YTHDF2 之间的相互作用。
circ_SFMBT2 和 LATS2 在 NSCLC 细胞和组织中表达水平较低。circ_SFMBT2 与 LATS2 呈正相关，circ_SFMBT2 主要定位于细胞质中。circ_SFMBT2 过表达可负调控细胞增殖、活力、迁移和上皮-间充质转化，同时促进 Hippo/YAP 通路激活。值得注意的是，沉默 LATS2 可有效消除 circ_SFMBT2 过表达对 NSCLC 细胞恶性的抑制作用。此外，m6A 特异性富集于 circ_SFMBT2 中，circ_SFMBT2 可与 YTHDF2 结合。沉默 YTHDF2 可增加 circ_SFMBT2 的表达，同时抑制癌细胞的恶性。
我们的研究结果表明，YTHDF2 可通过介导 circ_SFMBT2 的降解促进 Hippo/YAP 通路的激活，从而促进 NSCLC 细胞的增殖和转移。
