New insights into the crossroads between EMT and stemness in the context of cancer

The epithelial-mesenchymal transition (EMT) is an example of cellular plasticity, where an epithelial cell acquires a mesenchymal-like phenotype that increases its migratory and invasive properties. Stemness is the ability of stem cells to proliferate in an asymmetric way that allows them to maintain the reservoir of undifferentiated cells with stem cell identity, but also to produce new differentiated cells. Initial works revealed that activation of the EMT program in epithelial cells induces the acquisition of stem cell properties, which in the context of cancer may contribute to the appearance of tumor initiating cells (TIC). However, a number of groups have recently reported that mesenchymal-epithelial transition (MET) is required for efficient metastatic colonization and that EMT may be not necessarily associated with stemness. In this review, we summarize recent findings that extend our knowledge about the crossroads between EMT and stemness and their relevance under physiological or pathological conditions

Resminostat induces changes in epithelial plasticity of hepatocellular carcinoma cells and sensitizes them to sorafenib-induced apoptosis

Resminostat, a novel class I, IIb, and IV histone deacetylase inhibitor, was studied in advanced hepatocellular carcinoma (HCC) patients after relapse to sorafenib (SHELTER study). In this phase I/II clinical trial, combination of sorafenib and resminostat was safe and showed early signs of efficacy. However, the molecular mechanisms behind this synergism have not been explored yet. In this work, we aimed to analyze whether resminostat regulates epithelial-mesenchymal and stemness phenotype as a mechanism of sensitization to sorafenib. Three HCC cell lines with differences in their epithelial/mesenchymal characteristics were treated with resminostat and sorafenib alone, or in combination. Resminostat prevented growth and induced cell death in the HCC cells, in a time and dose dependent manner. A collaborative effect between resminostat and sorafenib was detected in the mesenchymal HCC cells, which were insensitive to sorafenib-induced apoptosis. Expression of mesenchymal-related genes was decreased in resminostat-treated HCC cells, concomitant with an increase in epithelial-related gene expression, organized tight junctions and reduced invasive growth. Moreover, resminostat down-regulated CD44 expression, coincident with decreased capacity to form colonies at low cell density

Epithelial–Mesenchymal Transition (EMT) Induced by TGF-β in Hepatocellular Carcinoma Cells Reprograms Lipid Metabolism

(1) Background: The transforming growth factor (TGF)-β plays a dual role in liver carcinogenesis. At early stages, it inhibits cell growth and induces apoptosis. However, TGF-β expression is high in advanced stages of hepatocellular carcinoma (HCC) and cells become resistant to TGF-β induced suppressor effects, responding to this cytokine undergoing epithelial-mesenchymal transition (EMT), which contributes to cell migration and invasion. Metabolic reprogramming has been established as a key hallmark of cancer. However, to consider metabolism as a therapeutic target in HCC, it is necessary to obtain a better understanding of how reprogramming occurs, which are the factors that regulate it, and how to identify the situation in a patient. Accordingly, in this work we aimed to analyze whether a process of full EMT induced by TGF-β in HCC cells induces metabolic reprogramming. (2) Methods: In vitro analysis in HCC cell lines, metabolomics and transcriptomics. (3) Results: Our findings indicate a differential metabolic switch in response to TGF-β when the HCC cells undergo a full EMT, which would favor lipolysis, increased transport and utilization of free fatty acids (FFA), decreased aerobic glycolysis and an increase in mitochondrial oxidative metabolism. (4) Conclusions: EMT induced by TGF-β in HCC cells reprograms lipid metabolism to facilitate the utilization of FFA and the entry of acetyl-CoA into the TCA cycle, to sustain the elevated requirements of energy linked to this process

Role of the Transforming Growth Factor-β in regulating hepatocellular carcinoma oxidative metabolism.

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 profle of hepatocellular carcinoma (HCC) cells that show diferences in TGF-β expression. Oxygen consumption rate (OCR), extracellular acidifcation 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 signifcant diferences in glycolytic activity. Concomitantly, enhanced glutamine anaplerosis and biosynthetic use of TCA metabolites were proved through analysis of metabolite levels, as well as metabolic fuxes 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 fux 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

Galunisertib suppresses the staminal phenotype in hepatocellular carcinoma by modulating CD44 expression

Cancer stem cells (CSCs) niche in the tumor microenvironment is responsible for cancer recurrence and therapy failure. To better understand its molecular and biological involvement in hepatocellular carcinoma (HCC) progression, one can design more effective therapies and tailored then to individual patients. While sorafenib is currently the only approved drug for first-line treatment of advanced stage HCC, its role in modulating the CSC niche is estimated to be small. By contrast, transforming growth factor (TGF)-β pathway seems to influence the CSC and thus may impact hallmarks of HCC, such as liver fibrosis, cirrhosis, and tumor progression. Therefore, blocking this pathway may offer an appealing and druggable target. In our study, we have used galunisertib (LY2157299), a selective ATP-mimetic inhibitor of TGF-β receptor I (TGFβI/ALK5) activation, currently under clinical investigation in HCC patients. Because the drug resistance is mainly mediated by CSCs, we tested the effects of galunisertib on stemness phenotype in HCC cells to determine whether TGF-β signaling modulates CSC niche and drug resistance. Galunisertib modulated the expression of stemness-related genes only in the invasive (HLE and HLF) HCC cells inducing a decreased expression of CD44 and THY1. Furthermore, galunisertib also reduced the stemness-related functions of invasive HCC cells decreasing the formation of colonies, liver spheroids and invasive growth ability. Interestingly, CD44 loss of function mimicked the galunisertib effects on HCC stemness-related functions. Galunisertib treatment also reduced the expression of stemness-related genes in ex vivo human HCC specimens. Our observations are the first evidence that galunisertib effectiveness overcomes stemness-derived aggressiveness via decreased expression CD44 and THY1

Galunisertib suppresses the staminal phenotype in hepatocellular carcinoma by modulating CD44 expression

Cancer stem cells (CSCs) niche in the tumor microenvironment is responsible for cancer recurrence and therapy failure. To better understand its molecular and biological involvement in hepatocellular carcinoma (HCC) progression, one can design more effective therapies and tailored then to individual patients. While sorafenib is currently the only approved drug for first-line treatment of advanced stage HCC, its role in modulating the CSC niche is estimated to be small. By contrast, transforming growth factor (TGF)-beta pathway seems to influence the CSC and thus may impact hallmarks of HCC, such as liver fibrosis, cirrhosis, and tumor progression. Therefore, blocking this pathway may offer an appealing and druggable target. In our study, we have used galunisertib (LY2157299), a selective ATP-mimetic inhibitor of TGF-beta receptor I (TGF beta I/ALK5) activation, currently under clinical investigation in HCC patients. Because the drug resistance is mainly mediated by CSCs, we tested the effects of galunisertib on stemness phenotype in HCC cells to determine whether TGF-beta signaling modulates CSC niche and drug resistance. Galunisertib modulated the expression of stemness-related genes only in the invasive (HLE and HLF) HCC cells inducing a decreased expression of CD44 and THY1. Furthermore, galunisertib also reduced the stemness-related functions of invasive HCC cells decreasing the formation of colonies, liver spheroids and invasive growth ability. Interestingly, CD44 loss of function mimicked the galunisertib effects on HCC stemness-related functions. Galunisertib treatment also reduced the expression of stemness-related genes in ex vivo human HCC specimens. Our observations are the first evidence that galunisertib effectiveness overcomes stemness-derived aggressiveness via decreased expression CD44 and THY1

Galunisertib suppresses the staminal phenotype in hepatocellular carcinoma by modulating CD44 expression

Cancer stem cells (CSCs) niche in the tumor microenvironment is responsible for cancer recurrence and therapy failure. To better understand its molecular and biological involvement in hepatocellular carcinoma (HCC) progression, one can design more effective therapies and tailored then to individual patients. While sorafenib is currently the only approved drug for first-line treatment of advanced stage HCC, its role in modulating the CSC niche is estimated to be small. By contrast, transforming growth factor (TGF)-beta pathway seems to influence the CSC and thus may impact hallmarks of HCC, such as liver fibrosis, cirrhosis, and tumor progression. Therefore, blocking this pathway may offer an appealing and druggable target. In our study, we have used galunisertib (LY2157299), a selective ATP-mimetic inhibitor of TGF-beta receptor I (TGF beta I/ALK5) activation, currently under clinical investigation in HCC patients. Because the drug resistance is mainly mediated by CSCs, we tested the effects of galunisertib on stemness phenotype in HCC cells to determine whether TGF-beta signaling modulates CSC niche and drug resistance. Galunisertib modulated the expression of stemness-related genes only in the invasive (HLE and HLF) HCC cells inducing a decreased expression of CD44 and THY1. Furthermore, galunisertib also reduced the stemness-related functions of invasive HCC cells decreasing the formation of colonies, liver spheroids and invasive growth ability. Interestingly, CD44 loss of function mimicked the galunisertib effects on HCC stemness-related functions. Galunisertib treatment also reduced the expression of stemness-related genes in ex vivo human HCC specimens. Our observations are the first evidence that galunisertib effectiveness overcomes stemness-derived aggressiveness via decreased expression CD44 and THY1

Exploring the structural requirements for inhibition of the ubiquitin E3 ligase breast cancer associated protein 2 (BCA2) as a treatment for breast cancer

The zinc-ejecting aldehyde dehydrogenase (ALDH) inhibitory drug disulfiram (DSF) was found to be a breast cancer-associated protein 2 (BCA2) inhibitor with potent antitumor activity. We herein describe our work in the synthesis and evaluation of new series of zinc-affinic molecules to explore the structural requirements for selective BCA2-inhibitory antitumor activity. An N(C═S)S—S motif was found to be required, based on selective activity in BCA2-expressing breast cancer cell lines and against recombinant BCA2 protein. Notably, the DSF analogs (3a and 3c) and dithio(peroxo)thioate compounds (5d and 5f) were found to have potent activity (submicromolar IC50) in BCA2 positive MCF-7 and T47D cells but were inactive (IC50 > 10 μM) in BCA2 negative MDA-MB-231 breast cancer cells and the normal breast epithelial cell line MCF10A. Testing in the isogenic BCA2 +ve MDA-MB-231/ER cell line restored antitumor activity for compounds that were inactive in the BCA2 −ve MDA-MB-231 cell line. In contrast, structurally related dithiocarbamates and benzisothiazolones (lacking the disulfide bond) were all inactive. Compounds 5d and 5f were additionally found to lack ALDH-inhibitory activity, suggestive of selective E3 ligase-inhibitory activity and worthy of further development

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

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