Purpose: Cisplatin (DDP) based chemotherapy regimens are widely used in advanced gastric cancer (GC). Drug resistance often limited the clinical benefits of cisplatin regimen. The mechanisms of cisplatin resistance have not been fully revealed. Therefore, further exploration of the relevant molecular mechanisms is urgently needed.
Patients and methods: DDP resistance associated miRNA of GC microarray dataset GSE86195 was obtained from the National Center for Biotechnology Information (NCBI) GEO database, GEO2R was applied to compare the samples in two different groups under the same experimental conditions. |log₂(Fold Change) | (log₂(FC)) was selected as the criteria to screen the statistically significant DE-miRNAs. StarBaseV3.0 was used to predict the target genes of the DE-miRNAs. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses of target genes of DE-miRNAs were carried out using DAVID. The STRING database was applied to estimate the correlations between target genes. Analysis of hubgenes by coremine and The Human Protein Atlas (THPA). Initial expression validations of miR-424 and miR-491-5p, SMURF1 and BCL2L1 were carried out using clinical pathological specimens by RT-PCR.
Results: A total of 13 Differential expression-miRNAs (DE-miRNAs) were identified in DDP chemoresistant cells, including 9 upregulated miRNAs and 4 downregulated miRNAs. SMURF1 and BCL2L1 were screened as the critical genes in DDP-resistant GC, which were regulated by miR-424 and miR-491-5p respectively. The results of validation of hub genes expression in GC tissues indicated that in DFS<1-year group, the expression of miR-424 decreased significantly, notably upregulated expression of SMURF1 was also detected.
Conclusion: Our results implied that miR-424, as a tumor suppressor, could deregulate SMURF1 in DDP-resistant GC cells.
Keywords: gastric cancer, cisplatin drug resistance, miRNAs