Inhibitors of Na+/K+ ATPase exhibit antitumor effects on multicellular tumor spheroids of hepatocellular carcinoma

Yeonhwa Song,Su-Yeon Lee,David Shum,Haeng Ran Seo,Sanghwa Kim,Se-Hyuk Kim,Inhee Choi,Kang Mo Kim,Jinyeong Heo,A-Ram Kim

doi:10.1038/s41598-020-62134-4

Abstract

Hepatocellular carcinoma (HCC), one of the most common malignant cancers worldwide, is associated with substantial mortality. Because HCCs have strong resistance to conventional chemotherapeutic agents, novel therapeutic strategies are needed to improve survival in patients with HCC. The multicellular tumor spheroid (MCTS) model is a powerful method for anticancer research because of its ability to mimic the complexity and heterogeneity of tumor tissue, the three-dimensional cellular context of tumor tissue, and the pathophysiological gradients of in vivo tumors. However, it is difficult to obtain meaningful results from the MCTS model without considering the conditions of clinical tumors. We, therefore, provided a proof of concept to determine whether spheroid models simulate in vivo tumor microenvironments. Through a high-throughput screening for HCC therapy using the MCTS model, we selected inhibitors of Na+/K+-ATPase (ouabain and digoxin) that could suppress cell growth and migration via inhibition of the epithelial-mesenchymal transition of HCC in vivo and in vitro. The results showed that this model provides a new paradigm for high-throughput drug screening and will significantly improve the efficiency of identifying new drugs for HCC treatment. Through utilization of MCTS models, here we found that inhibitors of Na+/K+-ATPase may be feasible as a novel target to sensitize HCC cells.

Highlights

Hepatocellular carcinoma (HCC), one of the most common malignant cancers worldwide, is associated with substantial mortality
We aimed to develop more complicated multicellular tumor spheroid (MCTS) models to recapitulate the in vivo tumor microenvironment (TME) of HCC
Before the development of the MCTS models, we performed a comparison study of drug sensitivities between tumor spheroids and patient-derived HCC tumor spheroids after treatment with 10 μM sorafenib

Summary

Introduction

Hepatocellular carcinoma (HCC), one of the most common malignant cancers worldwide, is associated with substantial mortality. A complex www.nature.com/scientificreports three-dimensional (3D) cell culture system better replicates the 3D cellular context and simulates therapeutically relevant parameters of in vivo tumors, such as pH and oxygen gradients, the penetration of growth factors, and the distribution of proliferating/necrotic cells[9,10,11]. A 3D system better replicates an in vivo tumor because the drug must diffuse across multiple layers of cells to reach its target. Based on these considerations, we developed a 3D TME model to screen possible drugs for HCC. The multicellular tumor spheroid (MCTS) model has emerged as a powerful method to mimic the in vivo properties of a tumor, replicate tumor complexity, and predict drug efficacies for anticancer research. The MCTS model is an appropriate system that mimics the behavior of the EMT and the propagation of cancer cells in vivo

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