Downregulation of lncRNA APCDD1L-AS1 due to DNA hypermethylation and loss of VHL protein expression promotes the progression of clear cell renal cell carcinoma

Background:The current studies only indicated that long non-coding RNA (lncRNA) APCDD1L-AS1, as a novel lncRNA, may play a role in oral squamous cell carcinoma and lung cancer.However, its potential role in clear cell renal cell carcinoma (ccRCC) and its possible mechanism of action remain vague.Methods: TCGA-KIRC and GEO data and qRT-PCR and pyrosequencing results of clinical specimens were used to identify the expression level and DNA methylation status of APCDD1L-AS1.The effects of APCDD1L-AS1 overexpression on ccRCC growth and metastasis were determined by function experiments.Western blot and Tandem mass tags (TMT) were utilized to explore the relationship between APCDD1L-AS1 and VHL expression and its downstream underlying mechanisms.Results: The expression of APCDD1L-AS1 was downregulated in ccRCC.Decreased APCDD1L-AS1 expression was related to higher tumor stage and histological grade and shorter RFS (Relapse-free survival).Besides, APCDD1L-AS1 overexpression restrained the growth and metastasis of ccRCC cells in vitro and in vivo.Moreover, reduced APCDD1L-AS1 expression could be caused by DNA hypermethylation and loss of von Hippel Lindau (VHL) protein expression.Furthermore, the dysregulation of histones expression caused by APCDD1L-AS1 overexpression may be one of the important mechanisms to suppress the progression of ccRCC.Conclusion: APCDD1L-AS1 was able to inhibit the progression of ccRCC, and its decreased expression could be caused by DNA hypermethylation and loss of VHL protein expression.Therefore, APCDD1L-AS1 may serve as a new therapeutic target in the treatment of ccRCC.