Abstract: Objective To elucidate the role and expression pattern of COL6A5 in lung adenocarcinoma (LUAD). Methods The expression pattern of COL6A5 in LUAD was detected through Oncomine database. The relationship between COL6A5 and the prognosis of LUAD patients was analyzed by GEPIA database. The qPCR assay was used to detect the expression of RNA demethylase ALKBH5 in lung adenocarcinoma tissue. The m6A sites on COL6A5 was confirmed by bioinformatics analysis and MeRIP-qPCR experiment. The inhibitory effect of ALKBH5 on COL6A5 was detected by qPCR and Western blot assy. Bioinformatics analysis and Transwell assay were performed to determine the role of COL6A5 in LUAD. Results Oncomine analysis of the online database showed that the expression of COL6A5 was significantly reduced in LUAD. GEPIA database analysis showed that the level of COL6A5 mRNA expression was significantly lower in LUAD tissue than that of normal tissue (P＜0.05). qPCR result showed that COL6A5 mRNA expression was lower in LUAD tissues than that of adjacent normal tissues in 27 LUAD patients. Compared to normal pulmonary epithelial cells, COL6A5 mRNA was significantly inhibited in LUAD cells (P＜0.05). Furthermore, bioinformatics analysis and MeRIP-qPCR assay confirmed that there were m6A sites on COL6A5 mRNA. The expression level of ALKBH5 mRNA was higher in LUAD than that of adjacent normal tissues, and it was negatively correlated with COL6A5 mRNA expression (r=-0.599, P＜0.01). Knocking down ALKBH5 significantly enhanced COL6A5 expression in H1299 cells. After the analysis of co-expressed genes with COL6A5, it was found that COL6A5 may be involved in the regulation of life activities including epithelial transition, hemostasis, and cell surface interaction in LUAD cells. Results of Transwell assay and Western blot assay confirmed that the over-expression of COL6A5 could inhibit the invasion of H1299 cells. Conclusion The down regulated COL6A5 by ALKBH5 can inhibit the invasion metastasis of LUAD cells .

Key words: lung neoplasms, adenocarcinoma, neoplasm invasiveness, collagen type Ⅵ, AlkB homolog 5, RNA demethylas, computational biology, type Ⅵ collagen alpha-5 chain (COL6A5), m6A