Correction to "Aberrant methylation of secreted protein acidic and rich in cysteine gene and its significance in gastric cancer".

[This corrects the article on p. 6713 in vol. 25, PMID: 31857774.].

Aberrant methylation of secreted protein acidic and rich in cysteine gene and its significance in gastric cancer.

BACKGROUND: Aberrant methylation in DNA regulatory regions could downregulate tumor suppressor genes without changing the sequences. However, our knowledge of secreted protein acidic and rich in cysteine (SPARC) and its aberrant methylation in gastric cancer (GC) is still inadequate. In the present research, we performed fundamental research to clarify the precise function of methylation on SPARC and its significance in GC. AIM: To investigate promoter methylation and the effects of the SPARC gene in GC cells and tissues and to evaluate its clinical significance. METHODS: Plasmids that overexpressed the SPARC gene were transfected into human GC BGC-823 cells; non-transfected cells were used as a control group (NC group). Quantitative real-time polymerase chain reaction and western blotting (WB) were then used to detect the expression of SPARC. Methylation-specific polymerase chain reaction was executed to analyze the gene promoter methylation status. Cell viability was measured by the cell counting kit-8 assay. The migration and invasion ability of cells were detected by scratch assays and transwell chamber assays, respectively. Cell cycle events and apoptosis were observed with a flow cytometer. RESULTS: The expression of SPARC mRNA in GC tissues and cells was significantly lower and showed differing degrees of hypermethylation, respectively, than that in normal adjacent tissues and control cells. Treatment with 5-Aza-2'-deoxycytidine (5-Aza-Cdr) was able to restore the expression of SPARC and reverse promoter hypermethylation. Overexpression of the SPARC gene significantly inhibited proliferation, migration, and invasion of GC cells, while also causing cell cycle arrest and apoptosis; the NC group exhibited the opposite effects. CONCLUSION: This study demonstrated that SPARC could function as a tumor suppressor and might be silenced by promoter hypermethylation. Furthermore, in GC cells, SPARC inhibited migration, invasion, and proliferation, caused cell cycle arrest at the G0/G1 phase, and promoted apoptosis.

miR-1236-3p inhibits invasion and metastasis in gastric cancer by targeting MTA2.

BACKGROUND: MicroRNAs deregulation are common in human tumor progression. miR-1236-3p has been reported to function as tumor suppressor microRNA in various malignancies. The aim of this study was to demonstrate the downregulated expression of miR-1236-3p in gastric cancer (GC) tissues and cell lines, and clarify its biological function in GC. METHODS: Real-time polymerase chain reaction was used to measure the mRNA level of miR-1236-3p in GC. Dual luciferase assay was used to demonstrate that MTA2 was one of the candidate target genes of miR-1236-3p. Western blots were utilized to detect the protein levels. Cell function assays were also performed to determine the function of miR-1236-3p in GC. RESULTS: miR-1236-3p expression, which was associated with lymph node metastasis, differentiation and clinical stage, was significantly reduced in GC tissues and cell lines. miR-1236-3p over-expression could inhibit GC cell proliferation, migration and invasion, and inhibition of miR-1236-3p expression had opposite effects. Furthermore, we demonstrated that MTA2 was a candidate target of miR-1236-3p, and miR-1236-3p over-expression significantly inhibited the process of epithelial-mesenchymal transition. We also found that miR-1236-3p could suppress the PI3K/Akt signaling pathway in GC cells. CONCLUSIONS: Our results suggest that miR-1236-3p functions as a tumor suppressor in GC and could be a promising therapeutic target for GC.

Expression of miR-634 in gastric carcinoma and its effects on proliferation, migration, and invasion of gastric cancer cells.

This study aims to observe the expression of microRNA (miR)-634 in different gastric cancer cell lines and tissues, and to study the effects of miR-634 on the proliferation, migration, and invasion of the gastric cancer cells. The miR-634 mimics and miR-634 inhibitors were transfected by lentivirus into human gastric cancer SGC-7901 and MGC-803 cells, and the miR-634 cells without transfection were used as the control group (NC group). The expression of miR-634 in the transfected cells was detected by qRT-PCR. Cell viability was measured by the CCK8 assay. The migration and invasion ability of the cells were detected by scratch assays and Transwell® chamber assays, respectively, and the luciferase assay verified the binding of miR-634 to the target gene JAG1. The expression level of miR-634 in gastric cancer tissues and cell lines was significantly lower than that in normal adjacent tissues and control cells. The survival of cells was significantly decreased, and number of cells migrating and invading was decreased in the miR-634 mimics group. However, in the miR-634 inhibitor group, the opposite results were observed. Over-expression of miR-634 inhibited the proliferation, migration, and invasion of gastric cancer cell lines, and the miR-634 target gene was JAG1.