Cyano Enone-Bearing Triterpenoid Soloxolone Methyl Inhibits Epithelial-Mesenchymal Transition of Human Lung Adenocarcinoma Cells In Vitro and Metastasis of Murine Melanoma In Vivo.

Marina A. Zenkova,Nariman F. Salakhutdinov,Aleksandra V. Sen’kova,Oksana V. Salomatina,Kirill V. Odarenko,Andrey V. Markov

doi:10.3390/molecules25245925

Abstract

Introduction of α-cyano α,β-unsaturated carbonyl moiety into natural cyclic compounds markedly improves their bioactivities, including inhibitory potential against tumor growth and metastasis. Previously, we showed that cyano enone-bearing derivatives of 18βH-glycyrrhetinic (GA) and deoxycholic acids displayed marked cytotoxicity in different tumor cell lines. Moreover, GA derivative soloxolone methyl (SM) was found to induce ER stress and apoptosis in tumor cells in vitro and inhibit growth of carcinoma Krebs-2 in vivo. In this work, we studied the effects of these compounds used in non-toxic dosage on the processes associated with metastatic potential of tumor cells. Performed screening revealed SM as a hit compound, which inhibits motility of murine melanoma B16 and human lung adenocarcinoma A549 cells and significantly suppresses colony formation of A549 cells. Further study showed that SM effectively blocked transforming growth factor β (TGF-β)-induced epithelial-mesenchymal transition (EMT) of A549 cells: namely, inhibited TGF-β-stimulated motility and invasion of tumor cells as well as loss of their epithelial characteristics, such as, an acquisition of spindle-like phenotype, up- and down-regulation of mesenchymal (vimentin, fibronectin) and epithelial (E-cadherin, zona occludens-1 (ZO-1)) markers, respectively. Network pharmacology analysis with subsequent verification by molecular modeling revealed that matrix metalloproteinases MMP-2/-9 and c-Jun N-terminal protein kinase 1 (JNK1) can be considered as hypothetical primary targets of SM, mediating its marked anti-EMT activity. The inhibitory effect of SM on EMT revealed in vitro was further confirmed in a metastatic model of murine B16 melanoma: SM was found to effectively block metastatic dissemination of melanoma B16 cells in vivo, increase expression of E-cadherin and suppress expression of MMP-9 in lung metastatic foci. Altogether, our data provided valuable information for a better understanding of the antitumor activity of cyano enone-bearing semisynthetic compounds and revealed SM as a promising anti-metastatic drug candidate.

Highlights

Epithelial-mesenchymal transition (EMT) is a reversible process during which tumor cells lose their apical-basal polarity and contacts with adjacent cells, as well as acquire motile and invasive behavior.epithelial-mesenchymal transition (EMT) is one of the key factors exerting a marked stimulation of tumor progression and metastasis, and weakening the sensitivity of tumor cells to chemo- and immunotherapy [1]
These cells can secrete an array of growth factors and cytokines, such as transforming growth factor β (TGF-β), epidermal growth factor (EGF), vascular endothelial growth factor (VEGF), interleukin 6 (IL-6) and others, which bind to the corresponding receptors exposed on the surface of tumor cells and thereby activate a complex network of signaling pathways with subsequent up-regulation of EMT-associated transcription factors ZEB1/2, Snail, Slug and Twist1/2 that orchestrate EMT program [1,5]
On the first step of the study the cytotoxicity of mentioned compounds was studied in murine melanoma B16 and human lung adenocarcinoma A549 cells

Summary

Introduction

Epithelial-mesenchymal transition (EMT) is a reversible process during which tumor cells lose their apical-basal polarity and contacts with adjacent cells, as well as acquire motile and invasive behavior.EMT is one of the key factors exerting a marked stimulation of tumor progression and metastasis, and weakening the sensitivity of tumor cells to chemo- and immunotherapy [1]. EMT of tumor cells can be induced by different stimulus from tumor microenvironment, primarily the stromal cells, surrounding the malignant tissue, e.g., myeloid-derived suppressor cells, cancer-associated fibroblasts and macrophages [5]. These cells can secrete an array of growth factors and cytokines, such as transforming growth factor β (TGF-β), epidermal growth factor (EGF), vascular endothelial growth factor (VEGF), interleukin 6 (IL-6) and others, which bind to the corresponding receptors exposed on the surface of tumor cells and thereby activate a complex network of signaling pathways with subsequent up-regulation of EMT-associated transcription factors ZEB1/2, Snail, Slug and Twist1/2 that orchestrate EMT program [1,5]. EMT plays a key role in malignant progression and increase of severity of metastasis

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