Thioredoxin Downregulation Enhances Sorafenib Effects in Hepatocarcinoma Cells.

María José López-Grueso,José Antonio Bárcena,Raúl González,Jordi Muntané,C Alicia Padilla

doi:10.3390/antiox8100501

Abstract

Sorafenib is the first-line recommended therapy for patients with advanced hepatocarcinoma (HCC) in de-differentiation stage (presenting epithelial–mesenchymal transition, EMT). We studied the role of the thioredoxin system (Trx1/TrxR1) in the sensitivity or resistance of HCC cells to the treatment with Sorafenib. As a model, we used a set of three established HCC cell lines with different degrees of de-differentiation as occurs in metastasis. By quantitative proteomics, we found that the expression levels of Trx1 and TrxR1 followed the same trend as canonical EMT markers in these cell lines. Treatment with Sorafenib induced thiol redox reductive changes in critical elements of oncogenic pathways in all three cell lines but induced drastic proteome reprograming only in HCC cell lines of intermediate stage. Trx1 downregulation counteracted the thiol reductive effect of Sorafenib on Signal Transducer and Activator of Transcription 3 (STAT3) but not on Mitogen-Activated Protein Kinase (MAPK) or Protein Kinase B (Akt) and transformed advanced HCC cells into Sorafenib-sensitive cells. Ten targets of the combined Sorafenib–siRNATrx1 treatment were identified that showed a gradually changing expression trend in parallel to changes in the expression of canonical EMT markers, likely as a result of the activation of Hippo signaling. These findings support the idea that a combination of Sorafenib with thioredoxin inhibitors should be taken into account in the design of therapies against advanced HCC.

Highlights

Hepatocarcinoma (HCC) represents 80% of the primary hepatic neoplasms that appear mainly in a context of chronic liver cirrhosis
A “label-free” quantitative proteomics analysis detected 1170 proteins with significant differences between HepG2, SNU423, and SNU475 cell lines (Supplementary File S1). This is the first comparative proteomic analysis carried out with these cell lines, and the results obtained for canonical markers of Epithelial–mesenchymal transition (EMT) showed increasing and decreasing gradients, in agreement with the classification of these human HCC cells as epithelial or mesenchymal [29,30]
The members of the Trx system Trx1 and TrxR1 were present in increasing levels from HepG2 to SNU475 cells (Figure 1), which agrees with the role described for Trx1 as a pro-metastasis factor [31]

Summary

Introduction

Hepatocarcinoma (HCC) represents 80% of the primary hepatic neoplasms that appear mainly in a context of chronic liver cirrhosis. It is the sixth most frequent neoplasm, the third cause of cancer death, and accounts for 7% of registered malignancies [1]. HCC, as demonstrated in two large-scale trials [2] and the Asia-Pacific trial [3]. Epithelial–mesenchymal transition (EMT) is an important process that happens in normal development in which epithelial cells lose many of their properties to become mesenchymal cells by means of drastic changes in architecture and behavior. A similar transition occurs during tumor progression and malignant transformation, leading to increased cell motility and invasiveness.

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Discussion

Conclusion