Journal of Jilin University(Medicine Edition) ›› 2025, Vol. 51 ›› Issue (3): 653-662.doi: 10.13481/j.1671-587X.20250310

• Research in basic medicine • Previous Articles    

Inhibitory effect of silencing of circadian rhythm gene TIMELESS on immune escape of ovarian cancer SK-OV-3 cells and its mechanism

Yuling GU,Cui ZHENG,Yunxian TANG()   

  1. Department of Obstetrics and Gynecology,Suzhou Municipal Hospital,Affiliated Suzhou Hospital,Nanjing Medical University,Nanjing 215000,China
  • Received:2024-07-18 Accepted:2024-09-07 Online:2025-05-28 Published:2025-07-18
  • Contact: Yunxian TANG E-mail:guyuling95@163.com

Abstract:

Objective To discuss the effect of circadion rhythm gene TIMELESS (TIM) silencing on immune escape of the ovarian cancer cells, and to clarify its related mechanism. Methods The CD8+T lymphocytes were isolated and identified by flow cytometry to detect the proportion of CD3+/CD8+ cell subsets. The human ovarian cancer SK-OV-3 cells were cultured in vitro and divided into interference plasmid transfected with TIM small interfering (siRNA) (si-TIM), negative control plasmid (si-NC), programmed death ligand 1 (PD-L1) over-expression plasmid (oe-PD-L1), and negative control plasmid (oe-NC) groups. The cells were further divided into blank control group (BC group, non-transfection), si-NC group (transfected with si-NC), si-TIM group(transfected with si-TIM), si-NC+oe-NC group (transfected with si-NC and oe-NC), and si-TIM+oe-PD-L1 group (transfected with si-TIM and oe-PD-L1). Real-time fluorescence quantitative PCR(RT-qPCR) and Western blotting methods were used to detect the expression levels of TIM mRNA and protein in the SK-OV-3 cells to verify TIM gene silencing. The transfected SK-OV-3 cells were co-cultured with activated CD8+T lymphocytes and divided into BC group (SK-OV-3 cells cultured alone), BC/T group, si-NC/T group, si-TIM/T group, si-NC+oe-NC/T group, and si-TIM+oe-PD-L1/T group. CCK-8 method was used to detect the survival rates of the SK-OV-3 cells in various groups; flow cytometry was used to detect the apoptotic rates of the SK-OV-3 cells and positive expression rate of PD-L1 on surface of the cells in various groups; enzyme-linked immunosorbent assay (ELISA) method was used to detect the levels of interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α) in the co-culture supernatant; lactate dehydrogenase (LDH) release assay was used to detect the cytotoxicity of the CD8+T lymphocytes in various groups; RT-qPCR method was used to detect the expression levels of TIM and PD-L1 mRNA in the SK-OV-3 cells in various groups; Western blotting method was used to detect the expression levels of TIM and PD-L1 proteins in the SK-OV-3 cells in various groups. Results After scparated with immune magnetic bead method, the proportion of CD8+T lymphocyte (CD3+/CD8+) subsets was (96.56%±0.59%), indicating high purity of the extracted CD8+T lymphocytes. Compared with BC group, the expression levels of TIM mRNA and protein in the cells in si-TIM group were significantly decreased (P<0.01), suggesting successful TIM gene silencing in the ovarian cancer SK-OV-3 cells. The CCK-8 results showed that compared with BC group, the survival rate of the SK-OV-3 cells in BC/T group was significantly decreased (P<0.01); compared with BC/T group, the survival rate of the SK-OV-3 cells in si-TIM/T group was significantly decreased (P<0.01). The flow cytometry results showed that compared with BC group, the apoptotic rate of the SK-OV-3 cells in BC/T group was significantly increased (P<0.01); compared with BC/T group, the apoptotic rate of the SK-OV-3 cells in si-TIM/T group was significantly increased (P<0.01); compared with si-TIM/T group, the apoptotic rate of the SK-OV-3 cells in si-TIM+oe-PD-L1/T group was significantly decreased (P<0.01). Compared with BC group, the positive expression rate of PD-L1 on surface of the SK-OV-3 cells in si-TIM group was significantly decreased (P<0.01). The ELISA results showed that compared with BC/T group, the levels of IFN-γ and TNF-α in the culture supernatant in si-TIM/T group were significantly increased (P<0.01); compared with si-TIM/T group, the levels of IFN-γ and TNF-α in the supernatant in si-TIM+oe-PD-L1/T group were significantly decreased (P<0.01). The LDH release assay results showed that compared with BC/T group, the cytotoxicity of the CD8+T lymphocytes in si-TIM/T group was significantly increased (P<0.01); compared with si-TIM/T group, the cytotoxicity of the CD8+T lymphocytes in si-TIM+oe-PD-L1/T group was significantly weakened (P<0.01). The RT-qPCR and Western blotting results showed that compared with BC group, the expression levels of PD-L1 mRNA and protein in the SK-OV-3 cells in si-TIM group were significantly decreased (P<0.01); compared with si-TIM group, the expression level of PD-L1 protein in the cells in si-TIM+oe-PD-L1 group was significantly increased (P<0.01). Conclusion TIM gene silencing enhances the cytotoxic effect of CD8+T lymphocytes on ovarian cancer SK-OV-3 cells and inhibits immune escape, and its mechanism may be related to the regulation of PD-L1 protein expression.

Key words: Ovarian cancer, Immune escape, TIMELESS gene, CD8+T lymphocytes, Programmed death ligand 1

CLC Number: 

  • R737.31