A mesenchymal‐like phenotype and expression of CD44 predict lack of apoptotic response to sorafenib in liver tumor cells

Abstract

The multikinase inhibitor sorafenib is the only effective drug in advanced cases of hepatocellular carcinoma (HCC). However, response differs among patients and effectiveness only implies a delay. We have recently described that sorafenib sensitizes HCC cells to apoptosis. In this work, we have explored the response to this drug of six different liver tumor cell lines to define a phenotypic signature that may predict lack of response in HCC patients. Results have indicated that liver tumor cells that show a mesenchymal-like phenotype, resistance to the suppressor effects of transforming growth factor beta (TGF-b) and high expression of the stem cell marker CD44 were refractory to sorafenib-induced cell death in in vitro studies, which correlated with lack of response to sorafenib in nude mice xenograft models of human HCC. In contrast, epithelial-like cells expressing the stem-related proteins EpCAM or CD133 were sensitive to sorafenib-induced apoptosis both in vitro and in vivo. A cross-talk between the TGF-b pathway and the acquisition of a mesenchymal-like phenotype with up-regulation of CD44 expression was found in the HCC cell lines. Targeted CD44 knock-down in the mesenchymal-like cells indicated that CD44 plays an active role in protecting HCC cells from sorafenib-induced apoptosis. However, CD44 effect requires a TGF-b-induced mesenchymal background, since the only overexpression of CD44 in epithelial-like HCC cells is not sufficient to impair sorafenib-induced cell death. In conclusion, a mesenchymal profile and expression of CD44, linked to activation of the TGF-b pathway, may predict lack of response to sorafenib in HCC patients.Over the last few years, many targeted molecules have been proposed as potential treatments for advanced hepatocellular carcinoma (HCC).1,2 Among them, only sorafenib has shown survival improvement in patients and has become the standard of care in advanced cases.3 However, response differs among patients and effectiveness only consists in tumor progression delay. 4,5 Furthermore, a recent study suggests that HCC cells that acquired sorafenib resistance demonstrated a higher metastatic potential.6 Indeed, although the development of sorafenib represented a significant breakthrough, more effective therapeutic approaches are required in order to enhance or synergize with sorafenib effects and/or circumvent the mechanisms of tumor resistance to this drug. The epithelial-mesenchymal transition (EMT) is a physiological process during embryogenesis in which an epithelial cell loses expression of cell adhesion molecules and gains expression of mesenchymal components, which allows it to acquire motility and scattering properties.7 A closely related

Integrated Stable Isotope Labeling by Amino Acids in Cell Culture (SILAC) and Isobaric Tags for Relative and Absolute Quantitation (iTRAQ) Quantitative Proteomic Analysis Identifies Galectin-1 as a Potential Biomarker for Predicting Sorafenib Resistance in Liver Cancer*

“…Some tissue markers, such as ␣␤-crystallin (35), FGF3/FGF4 (36), JNK (37), and pERK (38) have been reported to predict sorafenib response. A recent study indicated that a mesenchymal profile and expression of CD44 may predict lack of response to sorafenib in HCC patients (39). Although various markers have been studied, identifying predictive biomarkers to sorafenib response remains challenging and warrants further investigation.…”

Potential molecular, cellular and microenvironmental mechanism of sorafenib resistance in hepatocellular carcinoma

“…Therefore, it is postulated that sorafenib resistance is closely correlated with the dynamic changes of numerous molecules, especially their up-or down-regulated expression, involved in the mutual transition between epithelial and mesenchymal cell phenotypes and various signaling pathways. Particularly, epithelial cells are more susceptible to a Raf kinase inhibitor, sorafenib, whereas mesenchymal cells showed significant resistance [68,69]. In addition, PI3K/Akt showed higher activity and integrin-linked kinase (ILK) exhibit in the mesenchymal cells as compared to epithelial cells [70,71].…”

CD44/CD44v6 a Reliable Companion in Cancer-Initiating Cell Maintenance and Tumor Progression

“…Beyond linked expression, CD44 actively promotes EMT (Cho et al, 2012; Ju et al, 2014; Nevo et al, 2014; Wang D. et al, 2014; Yu D. et al, 2014; Fernando et al, 2015; Jiang et al, 2015; Shang et al, 2015; Wang et al, 2015), e.g., by inhibiting E-cadherin-β-catenin complex formation accompanied by β-catenin translocation to the nucleus (Li and Zhou, 2011). There is evidence that Notch plays a central role.…”