ABSTRACT
@#[Abstract] Objective: To investigate the effects of miR-361-5p on the oxaliplatin (OXA) resistance of gastric cancer SGC-7901 cells and its mechanism. Methods: The expression of miR-361-5p in gastric cancer cells (MKN-45, MGC80-3 and SGC-7901) and drug-resistant SGC-7901/OXA cells was detected by qPCR. The SGC-7901/OXA cells were transfected with miR-361-5p mimics/inhibitor or sh-CCND1 by using Liposome transfection technology. Then, cell proliferation, apoptosis and cell cycle of SGC-7901/OXA cells were measured by CCK-8 assay and Flow cytometry, respectively. The targeting relationship between miR-361-5p and CCND1 was examined by Dual luciferase report gene assay. The expression level of CCND1 in SGC-7901/OXA cells was detected by WB. Results: miR-361-5p was down-regulated in multiple gastric cancer cells and SGC-7901/OXA cells (P<0.05 or P<0.01). Over-expression of miR-361-5p significantly promoted the apoptosis, induced G0/G1 cell cycle arrest and inhibited cell proliferation of SGC-7901/OXA cells (P<0.05 or P<0.01). Dual luciferase reporter gene results verified that miR-361-5p targeted CCND1 and negatively regulated its expression (P<0.01). Further experiments showed that targeted down-regulation of CCND1 induced apoptosis and G0/G1 cell cycle arrest and inhibited CCND1 expression and proliferation of SGC-7901/OXA cells (P<0.05 or P<0.01). Over-expression of miR-361-5p targetedly down-regulated CCND1 and further promoted cell apoptosis, induced G0/G1 cell cycle arrest and inhibited cell proliferation of SGC-7901/OXA cells (P<0.05 or P<0.01). Conclusion: miR-361-5p over-expression can reverse the resistance of SGC-7901/OXA cells to OXA, and the mechanism may be related to its targeted down-regulation of CCND1 expression.
ABSTRACT
@#Objective: To explore the anti-tumor effects of oxaliplatin (OXA) combined with PD-1 antibody on colon cancer. Methods: Flow cytometry was used to detect the expression of PD-L1 in colon cancer cell lines HCT-116 and HT-29. Co-culture method was used to detect the secretion of cytokines and the changes of CD4/CD8 subsets in T-cells that co-cultured with HCT-116 cells, which were pretreated with OXAin combination with/without PD-1 antibody; The CT26 transplanted tumor model of colon cancer in BALB/c mice was established and treated with the combination of OXA and PD-1 to evaluate their anti-tumor efficacy. Meanwhile, CD8 antibody was used to scavenge CD8+ T cells in mice, and to evaluate the role of CD8+ T cells in the anti-tumor effect of OXA in vivo. Results: OXAcould significantly increase the expression of PD-L1 on the surface of colon cancer cells. Compared with pure T-cells, the T cells co-cultured with colon cancer HCT-116 cells that pre-treated by OXA, exhibited significantly reduced IL-2, IFN-γ and TNF levels (all P<0.05) in its culture supernatant and decreased ratio of CD4+memory T cell / CD8+TEMER (P<0.05), whereas there was increased cell proportion of the CD4+ (P>0.05) and CD8+ (P<0.05) naïve T cells. After co-treated with PD-1 antibody, compared with the single treatment of OXA, IFN-γ and IL-10 content (P<0.05) in culture supernatant and the subsets of CD8+ TCM and TEMRA ratio (P>0.05) were increased. In vivo experiments showed that OXAcombined with PD-1 antibody could enhance its anti-tumor activity, the tumor suppression rates were 25.6% (OXA) and 29.1% (αPD-1), respectively, however, the rate of tumor inhibition was increased to 58.2% when combined (P<0.05, compared to OXA or αPD-1 group). After scavenging CD8+T cells in mice, the antitumor activity of OXA dropped from 68.4% to 46.2% (P<0.05). Conclusion: OXA combined with PD-1 antibody had synergistic anti-tumor effect, and CD8+ T cells played an important role in the antitumor activity of OXA.