Published online Dec 21, 2019. doi: 10.3748/wjg.v25.i47.6823
Peer-review started: September 23, 2019
First decision: November 4, 2019
Revised: November 15, 2019
Accepted: November 29, 2019
Article in press: November 29, 2019
Published online: December 21, 2019
Gastric adenocarcinoma (GAC) is one of the leading causes of cancer-related death. However, delayed diagnosis is found in most patients with proximal or distal metastasis due to the nontypical symptoms of early GAC, which results in poor treatment and prognosis. Therefore, it is important to further reveal novel diagnostic and therapeutic methods as well as the underlying molecular mechanism of GAC.
Plenty of evidence indicates that the poor prognosis of GAC is significantly related to many molecular biomarkers, such as microRNA (miRNA). Previous studies have demonstrated that miRNA dysregulation significantly influences the prognosis of gastric cancer patients (e.g., miRNA-203, miR-21, and miR-25). Thus, it is essential to search for novel miRNAs related to GAC prognosis, which may contribute to the development of GAC diagnosis.
This study aimed to search for new miRNA therapeutic targets for GAC and investigate the mechanism of differentially expressed miRNA (DEM) in vitro, which might provide some useful insights in improving the prognosis of GAC patients.
First, the miRNA expression profile data of GAC based on The Cancer Genome Atlas were obtained and used to screen DEMs and DEMs related to GAC prognosis by bioinformatics methods. Then, the expression of DEMs related to GAC prognosis was identified in GAC tumor samples and adjacent normal samples by qRT-PCR. ZDHHC5, a target gene of miR-96-5p, was predicted and confirmed by the luciferase reporter assay. Furthermore, MGC-803 cells were transfected with inhibitor NC, miR-96-5p inhibitor, si-ZDHHC5, or miR-96-5p inhibitor + si-ZDHHC5. Cell apoptosis was detected by flow cytometry. The expression of ZDHHC5, Bcl-2, and COX-2 was detected using western blotting.
A total of 299 DEMs and 35 DEMs related to GAC prognosis were screened based on the miRNA expression profile data from The Cancer Genome Atlas. Six miRNAs, including miR-96-5p, miR-222-5p, miR-652-5p, miR-125-5p, miR-145-3p, and miR-379-3p, were selected for identification in GAC tumor samples and adjacent normal samples. The results were consistent with bioinformatics analysis. Furthermore, miR-96-5p was considered as an important biomarker and investigated in in vitro experiments. Our results revealed that ZDHHC5 was a direct target gene of miR-96-5p, and miR-96-5p inhibition induced cell apoptosis and increased the expression of Bcl-2 and COX-2.
In conclusion, this work identified six miRNAs related to GAC prognosis, including miR-96-5p, miR-125-5p, miR-145-3p, miR-222-5p, miR-379-3p, and miR-652-5p. Furthermore, downregulated miR-96-5p markedly induced cell apoptosis through targeting ZDHHC5.
Current findings provide a potential molecular mechanism of miR-96-5p in GAC. However, further studies are needed to investigate the mechanism and prognostic significance of these miRNAs in GAC.