Identification of ALDH7A1 as a DNA-methylation-driven gene in lung squamous cell carcinoma

Deoxyribose nucleic acid (DNA) methylation is an important epigenetic modification that plays an important role in the occurrence and development of tumors. Identifying key methylation-driven genes that affect the prognosis of lung squamous cell carcinoma (LUSC) can provide direction for targeted therapy research. Methylation and RNA-seq data were downloaded from The Cancer Genome Atlas (TCGA). The MethylMix package was used to integrate and analyze the methylation and gene expression data from TCGA, and the LUSC dataset (GSE37745) was downloaded from GEO for validation. Forty-five DNA-methylation-driven genes (MDGs) were obtained, and 3 genes (TRIM61, SMIM22, and ALDH7A1) were significantly associated with survival by using univariate and multivariate Cox regression. A risk model was constructed. KM analysis showed that patients with high-risk scores had poor survival. A nomination plot for prognosis prediction of LUSC patients was constructed, which showed a good predictive efficiency for tumor prognosis. The high expression of ALDH7A1 was an independent risk factor for poor prognosis in LUSC. The expression of ALDH7A1 in LUSC was negatively correlated with its methylation status (COR = −0.655). GSEA analysis showed that high expression of ALDH7A1 could activate multiple signaling pathways (JAK-STAT signaling pathway and mTOR signaling pathway). <i>In vitro</i> cell experiments confirmed that in LUSC, silencing ALDH7A1 could inhibit tumor progression, while overexpression of ALDH7A1 could promote tumor progression. Our results indicated that ALDH7A1, a newly discovered MDG in LUSC, could act as an independent prognostic factor for OS in LUSC, with the potential to become a potential target for LUSC diagnosis and treatment. High expression of ALDH7A1 in LUSC could promote the occurrence and development of tumors. Signaling pathways, such as JAK-STAT and mTOR signaling pathways, might regulate the high expression of ALDH7A1.

脱氧核糖核酸（DNA）甲基化是一类重要的表观遗传修饰，在肿瘤的发生与发展中发挥关键作用。鉴定影响肺鳞状细胞癌（LUSC）预后的关键甲基化驱动基因，可为靶向治疗研究提供方向。本研究从癌症基因组图谱（TCGA）下载了甲基化与RNA测序（RNA-seq）数据，借助MethylMix软件包对TCGA的甲基化及基因表达数据进行整合分析，并从基因表达综合数据库（GEO）下载肺鳞状细胞癌数据集GSE37745用于验证。最终获得45个DNA甲基化驱动基因（MDGs），通过单因素及多因素Cox回归分析筛选出TRIM61、SMIM22与ALDH7A1这3个与患者生存显著相关的基因。本研究构建了风险预测模型，KM分析结果显示，高风险评分患者的生存预后较差。随后构建了用于肺鳞状细胞癌患者预后预测的列线图（nomogram），该列线图对肿瘤预后展现出良好的预测效能。研究发现，ALDH7A1高表达是肺鳞状细胞癌患者不良预后的独立危险因素；肺鳞状细胞癌中ALDH7A1的表达水平与其甲基化状态呈显著负相关（相关系数COR=-0.655）。基因集富集分析（GSEA）结果显示，ALDH7A1高表达可激活多条信号通路，包括JAK-STAT信号通路与mTOR信号通路。体外（in vitro）细胞实验证实，在肺鳞状细胞癌中，沉默ALDH7A1可抑制肿瘤进展，而过表达ALDH7A1则可促进肿瘤进展。本研究结果表明，ALDH7A1作为肺鳞状细胞癌中新发现的甲基化驱动基因，可作为肺鳞状细胞癌患者总生存期（Overall Survival，OS）的独立预后因子，有望成为肺鳞状细胞癌诊疗的潜在靶点。肺鳞状细胞癌中ALDH7A1高表达可促进肿瘤的发生与发展，JAK-STAT、mTOR等信号通路可能参与调控ALDH7A1的高表达。