Department of Otolaryngology Head and Neck Surgery, The Third Xiangya Hospital, Central South University, Changsha, 410013, Hunan, China.
Xiangya Clinical Research Center for Cancer Immunotherapy, Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China.
J Transl Med. 2022 Jun 8;20(1):264. doi: 10.1186/s12967-022-03446-z.
Nasopharyngeal carcinoma (NPC) is a malignant tumor of epithelial origin in head and neck with high incidence rate in Southern China. C2orf40 has been identified as a tumor suppressor gene in many cancers. However, the roles of C2orf40 in nasopharyngeal carcinoma has not been studied.
In this study, a bioinformatics analysis was performed to identify the differentially expressed genes in NPC. The quantitative methylation levels was detected using pyrosequencing. qRT-PCR, western blotting, immunohistochemistry and immunofluorescence were used to detect the expression level of related RNA and proteins. Cell proliferation was detected using CCK-8 assay, and colony formation capability was detected using colony formation assays. Cell migration and invasion were analyzed using wound-healing and Transwell assays, respectively. The apoptosis level of cells was assessed using TUNEL staining. Endogenous DNA damage and repair were assessed by the comet assay. Cell cycle analyses carried out by flow cytometry. Finally, We used a xenograft nude mouse to verify the roles of C2orf40 in chemoresistance and radioresistance in vivo.
We found that the C2orf40 expression was significantly downregulated in NPC tissues and inversely associated with a poor prognosis. In vivo and in vitro functional experiments confirmed that overexpression of C2orf40 significantly inhibited the migration and invasion of NPC cells, and promoted their sensitivity to radiotherapy and chemotherapy of NPC cells. Mechanically, the expression level of C2orf40 was negatively correlated with the expression levels of CCNE1 and CDK1. Overexpression of C2orf40 induced cell cycle arrest of NPC cells at G/M phase. In addition, C2orf40 can down-regulated the expression levels of homologous recombination-related proteins (BRCA1, BRCA2, RAD51, and CDC25A) and inhibited the activity of the PI3K/AKT/mTOR signaling pathway.
The results clarified the biological functions and mechanisms of C2orf40, as a tumor suppressor gene, in NPC, and provided a potential molecular target for improving the sensitivity of NPC to radiotherapy and chemotherapy.
鼻咽癌（NPC）是头颈部上皮来源的恶性肿瘤，在中国南方的发病率较高。C2orf40 已被确定为许多癌症中的肿瘤抑制基因。然而，C2orf40 在鼻咽癌中的作用尚未得到研究。
本研究通过生物信息学分析鉴定 NPC 中的差异表达基因。使用焦磷酸测序检测定量甲基化水平。qRT-PCR、western blot、免疫组化和免疫荧光检测相关 RNA 和蛋白的表达水平。CCK-8 检测细胞增殖，集落形成实验检测集落形成能力。划痕愈合和 Transwell 实验分别分析细胞迁移和侵袭。TUNEL 染色评估细胞凋亡水平。彗星实验评估内源性 DNA 损伤和修复。流式细胞术进行细胞周期分析。最后，我们使用异种移植裸鼠在体内验证 C2orf40 在 NPC 化疗和放疗耐药中的作用。
我们发现 C2orf40 的表达在 NPC 组织中显著下调，与预后不良呈负相关。体内外功能实验证实，过表达 C2orf40 显著抑制 NPC 细胞的迁移和侵袭，并促进 NPC 细胞对放疗和化疗的敏感性。从机制上讲，C2orf40 的表达水平与 CCNE1 和 CDK1 的表达水平呈负相关。C2orf40 的过表达导致 NPC 细胞周期停滞在 G/M 期。此外，C2orf40 可以下调同源重组相关蛋白（BRCA1、BRCA2、RAD51 和 CDC25A）的表达水平，并抑制 PI3K/AKT/mTOR 信号通路的活性。
这些结果阐明了 C2orf40 作为肿瘤抑制基因在 NPC 中的生物学功能和机制，并为提高 NPC 对放疗和化疗的敏感性提供了潜在的分子靶点。
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