Atorvastatin Attenuates Programmed Death Ligand-1 (PD-L1) Induction in Human Hepatocellular Carcinoma Cells

• Main Authors: Thuzar Hla Shwe, Peraphan Pothacharoen, Thanyaluck Phitak, Benjawan Wudtiwai, Prachya Kongtawelert
• Format: Article
• Language: English
• Published: MDPI AG 2021-08-01
• Series: International Journal of Molecular Sciences
• Subjects: PD-L1; IFNγ; TNFα; atorvastatin; liver cancer; HepG2
• Online Access: https://www.mdpi.com/1422-0067/22/16/8755

Liver cancer is the sixth most common cancer worldwide with high morbidity and mortality. Programmed death ligand 1 (PD-L1) is a major ligand of programmed death 1 receptor (PD1), and PD1/PD-L1 checkpoint acts as a negative regulator of the immune system. Cancers evade the host’s immune defense via PD-L1 expression. This study aimed to investigate the effects of tumor-related cytokines, interferon gamma (IFNγ), and tumor necrosis factor alpha (TNFα) on PD-L1 expression in human hepatocellular carcinoma cells, HepG2. Furthermore, as atorvastatin, a cholesterol-lowering agent, is documented for its immunomodulatory properties, its effect on PD-L1 expression was investigated. In this study, through real-time RT-PCR, Western blot, and immunocytochemistry methods, PD-L1 expression in both mRNA and protein levels was found to be synergistically upregulated in HepG2 by a combination of IFNγ and TNFα, and STAT1 activation was mainly responsible for that synergistic effect. Next, atorvastatin can inhibit the induction of PD-L1 by either IFNγ alone or IFNγ/TNFα combination treatment in HepG2 cells. In conclusion, in HepG2 cells, expression of PD-L1 was augmented by cytokines in the tumor microenvironment, and the effect of atorvastatin on tumor immune response through inhibition of PD-L1 induction should be taken into consideration in cancer patients who have been prescribed atorvastatin.