Abstract
Resistance to chemotherapy is a major challenge in the effective treatment of patients with gastric cancer; however, the mechanisms underlying chemoresistance in gastric cancer cells are yet to be elucidated. MicroRNAs (miRNAs) have previously been associated with cancer progression and sensitivity to chemotherapy; therefore, the present study aimed to identify miRNAs that may influence the sensitivity of human gastric cancer cells to cisplatin (DDP) treatment. Initially, miRNAs that were differentially expressed between the DDP-sensitive SGC7901 human gastric cancer cell line and DDP-resistant SGC7901/DDP cell line were identified using high-throughput sequencing technology. miRNA-375 (miR-375), which was shown to be downregulated in the SGC7901/DDP cells, has previously been associated with numerous types of cancer; however, to the best of our knowledge, a role for miR-375 in the DDP-sensitivity of gastric cancer cells has yet to be explored. In the present study, the expression levels of miR-375 were significantly downregulated in the SGC7901/DDP cells, as compared with the SGC7901 cells, as demonstrated by reverse transcription-quantitative polymerase chain reaction. In addition, upregulation of miR-375 significantly enhanced the anti-proliferative and apoptosis-inducing effects of DDP, whereas downregulation of miR-375 decreased these effects. Subsequently, western blot analysis demonstrated that upregulation of miR-375 in the SGC7901/DDP cells increased their sensitivity to DDP treatment via regulating the protein expression levels of erb-b2 receptor tyrosine kinase 2 and phosphorylated-Akt. The results of the present study indicate that the expression levels of miR-375 may influence the sensitivity of human gastric cancer cells to the effects of DDP; thus suggesting that a combination of miR-375 regulation and DDP may be considered a novel strategy in the treatment of patients with chemoresistant gastric cancer.