Thyroid hormone T3 augments the cytotoxicity of sorafenib in Huh7 hepatocellular carcinoma cells by suppressing AKT expression.

Abstract

Hepatocellular carcinoma (HCC) is a primary cancer that poorly responds to treatment. Molecular cancer studies led to the development of kinase inhibitors, among which sorafenib stands out as a multi-kinase inhibitor approved by FDA for first line use in HCC patients. However, the efficiency of sorafenib was shown to be counteracted by numerous subcellular pathways involving the effector kinase AKT, causing resistance and limiting its survival benefit. On the way of breaking such resistance mechanisms and increase the efficiency of sorafenib, deeper understanding of hepatocellular physiology is essential. Thyroid hormones were shown to be metabolized in liver and inevitably affect the molecular behaviour of hepatocytes. Interestingly, thyroid hormone T3 was also demonstrated to be potentially influential in liver regeneration and treatment with this hormone reportedly led to a decrease in HCC tumor growths. In this study, we aimed to uncover the impact of T3 hormone on the cytotoxic response to sorafenib in HCC in vitro. We pre-treated the HCC cell line Huh-7 with T3 prior to sorafenib exposure both in 2D and 3D culture. We checked cell viability with MTT assay in 2D culture and measured the sizes of 3D spheroids with bright-field microscopy followed by a surface analysis with ImageJ. We also performed scratch assay to measure cell migration as well as western blot and qPCR to uncover affected pathways. We observed an additive effect to sorafenib's cytotoxicity both in 2D and 3D culture. Cell migration assay also confirmed our finding and pointed out a benefit of T3 hormone in HCC cell migration. Western blot experiments showed that T3 exerts its additive effect by suppressing AKT expression upon sorafenib treatment both at protein and gene expression levels. Our results open a promising new avenue in increasing sorafenib's cytotoxicity where thyroid hormone T3 is utilized to modulate AKT expression to combat resistance, and warrant further studies in the field.