The dual targeting of insulin and insulin-like growth factor 1 receptor enhances the mTOR inhibitor-mediated antitumor efficacy in hepatocellular carcinoma.

Claudia Pivonello,Leo J Hofland,Gaia Cuomo,Cristina De Angelis,Mariarosaria Negri,Francesco Izzo,Donatella Paola Provvisiero,Renata Simona Auriemma,Chiara Simeoli,Maria Cristina De Martino,Maria Napolitano,Rosario Pivonello,Annamaria Colao

doi:10.18632/oncotarget.6836

Abstract

Deregulation of mTOR and IGF pathways is frequent in hepatocellular carcinoma (HCC), thus mTOR and IGF1R represent suitable therapeutic targets in HCC. The aim of this study was to evaluate the effects of mTOR inhibitors (mTORi) and OSI-906, blocker of IGF1R/IR, on HCC cell proliferation, viability, migration and invasion, and alpha-fetoprotein (α-FP) secretion. In HepG2 and HuH-7 we evaluated, the expression of mTOR and IGF pathway components; the effects of Sirolimus, Everolimus, Temsirolimus and OSI-906 on cell proliferation; the effects of Sirolimus, OSI-906, and their combination, on cell secretion, proliferation, viability, cell cycle, apoptosis, invasion and migration. Moreover, intracellular mechanisms underlying these cell functions were evaluated in both cell lines. Our results show that HepG2 and HuH-7 present with the same mRNA expression profile with high levels of IGF2. OSI-906 inhibited cell proliferation at high concentration, while mTORi suppressed cell proliferation in a dose-time dependent manner in both cell lines. The co-treatment showed an additive inhibitory effect on cell proliferation and viability. This effect was not related to induction of apoptosis, but to G0/G1 phase block. Moreover, the co-treatment prevented the Sirolimus-induced AKT activation as escape mechanism. Both agents demonstrated to be differently effective in inhibiting α-FP secretion. Sirolimus, OSI-906, and their combination, blocked cell migration and invasion in HuH-7. These findings indicate that, co-targeting of IGF1R/IR and mTOR pathways could be a novel therapeutic approach in the management of HCC, in order to maximize antitumoral effect and to prevent the early development of resistance mechanisms.

Highlights

Hepatocellular carcinoma (HCC) is the sixth most common malignancy worldwide and the third most frequent cause of global cancer-related mortality [1, 2].If diagnosed at early stage, hepatocellular carcinoma (HCC) can be cured by surgical tumor resection or liver transplantation [2]
MTOR and insulin-like growth factor (IGF) pathway components are expressed in HCC cell lines and HCC tissues In the attempt to define the role of mammalian target of rapamycin (mTOR) and IGF pathways in HCC, RT-qPCR was performed to quantify the messenger expression level of mTOR, 4eBP1, p70S6K, IGF1, IGF2, IGF1 receptor (IGF1R), IGF2R and insulin receptor (IR), in THLE-2, HepG2 and HuH-7 cell lines, in normal liver and in HCC and peritumoral tissues
The messenger levels of mTOR and IGF pathway components of cell lines were compared to the normal hepatocytes (THLE-2) and are reported in Supplementary Table S1 as mean±S.E.M. mTOR components and activated forms of IGF1R and IR were expressed at protein levels in HepG2 and HuH-7 cells as shown in (Figure 1C, 1D, 1E and 1F)

Summary

Introduction

If diagnosed at early stage, HCC can be cured by surgical tumor resection or liver transplantation [2]. HCC has been shown to be chemoresistant to the most common chemotherapic compounds [2]. In this setting, targeted therapies could represent a new therapeutic option in HCC patients. Sorafenib, a small molecule multi-tyrosine kinase inhibitor, has been demonstrated to improve survival, in terms of median overall survival, in patients with advanced HCC [2, 5], approximately one-third of patients treated with sorafenib experience disease progression [6]. Novel treatment options are required in the management of HCC

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