Background/AimsThe role of DHRS3 in human cancer remains unclear. Our study explored the role of DHRS3 in gastric cancer (GC) and its clinicopathological significance and associated mechanisms.MaterialsBisulfite-assisted genomic sequencing PCR and a Mass-Array system were used to evaluate and quantify the methylation levels of the promoter. The expression levels and biological function of DHRS3 was examined by both in vitro and in vivo assays. A two-way hierarchical cluster analysis was used to classify the methylation profiles, and the correlation between the methylation status of the DHRS3 promoter and the clinicopathological characteristics of GC were then assessed.ResultsThe DHRS3 promoter was hypermethylated in GC samples, while the mRNA and protein levels of DHRS3 were significantly downregulated. Ectopic expression of DHRS3 in GC cells inhibited cell proliferation and migration in vitro, decreased tumor growth in vivo. DHRS3 methylation was correlated with histological type and poor differentiation of tumors. GC patients with high degrees of CpG 9.10 methylation had shorter survival times than those with lower methylation.ConclusionDHRS3 was hypermethylated and downregulated in GC patients. Reduced expression of DHRS3 is implicated in gastric carcinogenesis, which suggests DHRS3 is a tumor suppressor.

Recent studies have demonstrated that various long non‐coding RNAs (lncRNAs) participate in the gastric cancer (GC) development and metastasis. Some lncRNAs exert their regulatory function by interacting with microRNAs. Here we identified a novel lncRNA RP11‐81H3.2 that was highly expressed in the GC tissue and cell lines. RP11‐81H3.2 knockdown significantly inhibited the proliferation, migration, and invasion of GC cells. Mechanistically, we demonstrated that RP11‐81H3.2 directly interacted with miR‐339 while miR‐339 regulated the HNRNPA1 expression by targeting HRRNPA1 3’‐UTR. RP11‐81H3.2‐miR‐339‐HNRNPA1 interaction network regulated the GC cell proliferation, migration, and invasion. Moreover, our results confirmed that RP11‐81H3.2 knockdown suppressed the tumor growth of GC in a xenograft model in vivo. In summary, the results suggest that RP11‐81H3.2 functions as an oncogene in GC and could be utilized as a promising diagnosis and therapeutic marker for GC treatment.