Role of the Transforming Growth Factor-\u03b2 in regulating hepatocellular carcinoma oxidative metabolism

Jitka Soukupova,Petra Hyroššová,Antonio Zorzano,José Carlos Perales,Jordi Capellades,José Carlos Perales,Isabel Fabregat,María-Isabel Hernández-Alvarez,Esther Bertran,Andrea Malfettone,Isabel Fabregat,Alexandra Junza,Gianluigi Giannelli,Oscar Yanes,Gianluigi Giannelli,Petra Hyroššová,Oscar Yanes,Jordi Capellades,Alexandra Junza,Irene Peñuelas-Haro

doi:10.1038/s41598-017-12837-y

Abstract

Transforming Growth Factor beta (TGF-β) induces tumor cell migration and invasion. However, its role in inducing metabolic reprogramming is poorly understood. Here we analyzed the metabolic profile of hepatocellular carcinoma (HCC) cells that show differences in TGF-β expression. Oxygen consumption rate (OCR), extracellular acidification rate (ECAR), metabolomics and transcriptomics were performed. Results indicated that the switch from an epithelial to a mesenchymal/migratory phenotype in HCC cells is characterized by reduced mitochondrial respiration, without significant differences in glycolytic activity. Concomitantly, enhanced glutamine anaplerosis and biosynthetic use of TCA metabolites were proved through analysis of metabolite levels, as well as metabolic fluxes from U-13C6-Glucose and U-13C5-Glutamine. This correlated with increase in glutaminase 1 (GLS1) expression, whose inhibition reduced cell migration. Experiments where TGF-β function was activated with extracellular TGF-β1 or inhibited through TGF-β receptor I silencing showed that TGF-β induces a switch from oxidative metabolism, coincident with a decrease in OCR and the upregulation of glutamine transporter Solute Carrier Family 7 Member 5 (SLC7A5) and GLS1. TGF-β also regulated the expression of key genes involved in the flux of glycolytic intermediates and fatty acid metabolism. Together, these results indicate that autocrine activation of the TGF-β pathway regulates oxidative metabolism in HCC cells.

Highlights

Transforming Growth Factor beta (TGF-β) plays a dual role in liver tumorigenesis[1], since it inhibits growth and induces apoptosis in early stages of carcinogenesis, but once cells acquire the capacity to overcome its suppressor effects, they respond to it undergoing epithelial-mesenchymal transition (EMT), which increases their migratory and invasive potential
The amount of lactate released into the cell culture medium after 48 hours was slightly increased in the mesenchymal cells (Fig. 1d), increased glucose consumption was only observed in the Hep3B cells (Fig. 1e)
In previous studies from our group we postulated that differences in the expression of TGF-β correlate with differences in the expression of mesenchymal genes both in hepatocellular carcinoma (HCC) cell lines and in HCC patients[12]

Summary

Introduction

Transforming Growth Factor beta (TGF-β) plays a dual role in liver tumorigenesis[1], since it inhibits growth and induces apoptosis in early stages of carcinogenesis, but once cells acquire the capacity to overcome its suppressor effects, they respond to it undergoing epithelial-mesenchymal transition (EMT), which increases their migratory and invasive potential. For these reasons, targeting TGF-β has recently emerged as a promising tool in fighting liver cancer[2]. The potential role of TGF-β in regulating their metabolic profiles was explored in experiments where TGF-β function was activated with extracellular TGF-β1 or inhibited through targeting-knockdown of the TGF-β receptor I (TGFβRI)

Methods

Results

Conclusion