An Anticancer Bioactive Peptide Combined with Oxaliplatin Inhibited Gastric Cancer Cells In Vitro and In Vivo

Gastric cancer has become one of the major diseases threatening human health. This study aimed to investigate the mechanism of an anticancer bioactive peptide (ACBP) combined with oxaliplatin (OXA) on MKN-45, SGC7901, and NCI-N87 differentiated human gastric cancer cells and GES-1 immortalized human gastric mucosal epithelial cells. The therapeutic effect and action mechanism of short-term intermittent ACBP combined with OXA on nude mice with human gastric cancer were also investigated. The half-maximal inhibitory concentrations of these agents in these cells were measured by an MTT assay, and cell morphological changes were observed by H&E staining. The expression of Lin28, miR-107, miR-609, and Let-7 in these four cell lines was determined by q-PCR after drug treatment. Lin28 protein expression in these four cell lines treated with these drugs was measured by western blotting. Furthermore, activity and quality of life were observed daily in all tumor-bearing nude mice, and the expression of Lin28 in tumor tissue was determined by immunohistochemistry and RT-PCR. The results showed that ACBP inhibited the proliferation of MKN-45, SGC7901, and NCI-N87 gastric cancer cells in a dose-dependent manner and weakly suppressed the proliferation of GES-1 cells. Moreover, its inhibitory effect on proliferation was stronger in poorly differentiated gastric cancer cells. ACBP, OXA, and the combination upregulated Lin28 gene expression in MKN-45 cells and downregulated it in SGC7901 and GES-1 cells. ACBP and the combination therapy downregulated Let-7 expression in MKN-45 cells and upregulated Let-7 expression in SGC7901 cells. The combination of ACBP with OXA demonstrated significant anticancer sensitization. Moreover, it also significantly improved the quality of life of tumor-bearing nude mice and reduced the toxic side effects of chemotherapeutic drugs on nude mice. ACBP alone and in combination with oxaliplatin influenced the expression of tumor stem cell marker gene Lin28 and regulated the expression of microRNAs specifically regulated by Lin28. In addition, the anticancer effects and attenuated sensitization effects of ACBP may be related to the Lin28/miRNA-107 signaling pathway, acting by inhibiting the proliferation of cancerous stem cells. The findings of this study provide a scientific basis for exploring the antitumor mechanism of ACBP alone and combined with chemotherapeutic drugs.