Huang Yunyi, Chen Zhipei, Chen Xuanyi, Chen Xiaohua, Xu Meng
Hospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China.
J Oral Pathol Med. 2023 Jan;52(1):47-55. doi: 10.1111/jop.13382. Epub 2022 Nov 22.
34-kDa translocase of the outer mitochondrial membrane (TOMM34) has been reported highly expressed in many cancers and is positively correlated to poorer prognosis. Our prior study showed TOMM34 is highly expressed in oral squamous cell carcinoma (OSCC) and is closely related to TNM classification and tumor size. TOMM34 is also associated with lymph node metastasis and poorer overall survival and disease-free survival in HPV-negative OSCC.
We knocked down TOMM34 in OSCC cells (SCC15, HPV positive; Cal27, HPV negative) with siRNA and over-expressed with plasmids. The effects of TOMM34 on cell proliferation, migration and invasion abilities were detected by EdU assay, CCK-8 assay, wound-healing assay, and Transwell assay. We also detected the mitochondrial morphology and the intracellular Reactive Oxygen Species (ROS) level by fluorescence staining and flow cytometry. Finally, we monitored the protein levels of ERK pathway-related molecules.
TOMM34 knockdown decreased the proliferation in SCC15 and Cal27, and weakened the migration and invasion abilities as well. Mitochondria became shorter, in the shape of dots or short rods, suggesting that mitochondrial damage occurred. Intracellular ROS levels increased significantly after knockdown TOMM34 and decreased after over-expressing TOMM34. The phosphorylation levels of ERK1/2 and MEK1/2 in SCC15 were significantly higher than in Cal27. Besides, the phosphorylation levels of ERK1/2 and MEK1/2 were inhibited in SCC15 after knockdown of TOMM34, but not in Cal27.
TOMM34 promotes the cell proliferation, migration, and invasion of OSCC. In addition, TOMM34 participates in maintaining the mitochondrial shape and reducing the intracellular ROS level to protect cancer cells. Furthermore, TOMM34 increases the activity of ERK1/2 and MEK1/2 in HPV-positive OSCC cells but not in HPV-negative.
线粒体外膜转位酶34（TOMM34）在多种癌症中高表达，且与较差的预后呈正相关。我们之前的研究表明，TOMM34在口腔鳞状细胞癌（OSCC）中高表达，且与TNM分期和肿瘤大小密切相关。TOMM34还与HPV阴性的OSCC患者的淋巴结转移、较差的总生存期和无病生存期相关。
我们使用小干扰RNA（siRNA）敲低OSCC细胞（SCC15，HPV阳性；Cal27，HPV阴性）中的TOMM34，并通过质粒进行过表达。通过EdU检测、CCK-8检测、伤口愈合检测和Transwell检测，检测TOMM34对细胞增殖、迁移和侵袭能力的影响。我们还通过荧光染色和流式细胞术检测线粒体形态和细胞内活性氧（ROS）水平。最后，我们监测ERK通路相关分子的蛋白水平。
TOMM34敲低降低了SCC15和Cal27细胞的增殖，同时也削弱了它们的迁移和侵袭能力。线粒体变短，呈点状或短棒状，提示发生了线粒体损伤。敲低TOMM34后细胞内ROS水平显著升高，过表达TOMM34后则降低。SCC15中ERK1/2和MEK1/2的磷酸化水平显著高于Cal27。此外，敲低TOMM34后，SCC15中ERK1/2和MEK1/2的磷酸化水平受到抑制，但Cal27中未受抑制。
TOMM34促进OSCC细胞的增殖、迁移和侵袭。此外，TOMM34参与维持线粒体形态并降低细胞内ROS水平以保护癌细胞。此外，TOMM34增加HPV阳性OSCC细胞中ERK1/2和MEK1/2的活性，但在HPV阴性细胞中无此作用。
