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.
ABSTRACT
@#[Abstract] Objective: To investigate the effects of interleukin-18 over-expression on the in vitro and in vivo proliferation of human colorectal cancer (CRC) HCT-116 cells. Methods: A recombinant lentivirus vector containing human IL-18 gene fragment was constructed. Then theCRC HCT-116 cell line stably expressing human IL-18 (HCT-116/IL-18) was obtained by recombinant lentivirus transfection. In vitro proliferation of HCT-116/IL-18 cells and wild-type HCT-116 cells was determined by CCK-8 method. The expressions of IL-18, Cyclin D1, proliferating cell nuclear antigen (PCNA) and DNA damage repair enzyme (PARP) were detected by Western blotting. HCT-116 and HCT-116/IL-18 cells were inoculated into left and right axillas of Balb/c nude mice, respectively. Then the tumorigenicity and the growth of transplanted tumor were observed. The expressions of IL-18 and PCNAin xenograft tissues were detected by immunohistochemistry analysis. Results: IL-18 gene over-expression in HCT-116 cells could delay the proliferation of HCT-116 cells (P<0.05 or P<0.01). PARP expression was increased significantly and PCNA, Cyclin D1 expression were decreased in HCT-116/ IL-18 cells as compared to that of HCT-116 cells (P<0.01).The tumorigenicity of HCT-116/IL-18 cell was significantly decreased in nude mice with a tumor-formation rate of 43%; Compared with control group, HCT-116/IL-18cell line had a longer tumorigensis time, slower growth and smaller tumor volume; moreover, PCNAprotein expression was down-regulated in HCT-116/IL-18 xenograft tissuesas shown by immunohistochemistry analysis (P<0.01). Conclusion: IL-18 over-expression inhibited the growth and proliferation of HCT-116 cells both in vitro and in vivo, and the mechanism might berelated with IL-18 regulating cell cycle and promoting DNA damage.