Monocarboxylate transporter 1 and monocarboxylate transporter 4 in cancer-endothelial co-culturing microenvironments promote proliferation, migration, and invasion of renal cancer cells

Chen Guo,Tao Huang,Yan-Wei Cao,Zhen Dong,Hai-Tao Niu,En-Hao Kang,Wei Zhang,Qing-Hai Wang,Aashish Khanal,Hong Li

doi:10.1186/s12935-019-0889-8

Abstract

BackgroundThe Warburg effect demonstrates the importance of glycolysis in the development of primary and metastatic cancers. We aimed to explore the role of monocarboxylate transporter 1 (MCT1) and MCT4, two essential transporters of lactate, in renal cancer progression during cancer-endothelial cell co-culturing.MethodsRenal cancer cells (786-O) and human vascular endothelial cells (HUVECs) were single-cultured or co-cultured in transwell membranes in the presence or absence of a MCT-1/MCT-4 specific blocker, 7ACC1. Cell proliferation was evaluated with the CCK-8 kit, while cell migration, after a scratch and invasion in transwell chambers, was evaluated under a microscope. Real-time qPCR and western blot were employed to determine the mRNA and protein levels of MCT1 and MCT4, respectively. The concentration of lactic acid in the culture medium was quantified with an l-Lactic Acid Assay Kit.Results786-O cells and HUVECs in the co-culturing mode exhibited significantly enhanced proliferation and migration ability, compared with the cells in the single-culturing mode. The expression of MCT1 and MCT4 was increased in both 786-O cells and HUVECs in the co-culturing mode. Co-culturing promoted the invasive ability of 786-O cells, and markedly increased extracellular lactate. Treatments with 7ACC1 attenuated cell proliferation, migration, and invasion, and down-regulated the levels of MCT1/MCT4 expression and extracellular lactate.ConclusionsThe Warburg effect accompanied with high MCT1/MCT4 expression in the cancer-endothelial microenvironments contributed significantly to renal cancer progression, which sheds new light on targeting MCT1/MCT4 and glycolytic metabolism in order to effectively treat patients with renal cancers.

Highlights

The Warburg effect demonstrates the importance of glycolysis in the development of primary and metastatic cancers
A P value less than 0.05 was considered statistically significant. Both 786‐O Cells and human vascular endothelial cells (HUVECs) Had Significantly Higher Viability in the Co‐culture Mode Compared with Single‐culture Mode To test the in vitro role of monocarboxylate transporter 1 (MCT1) and MCT4 under the single-culture or co-culture conditions of 786-O cells or HUVECs, cell proliferation was determined by measuring viability via the Cell Counting Kit-8 (CCK-8) assay
7ACC1 did not exert anti-proliferative effect in either 786-O cells or HUVECs in single-culturing conditions (Fig. 1). These results suggested that co-culturing of 786-O cells and HUVECs markedly enhanced the proliferation of both cell lines, which was at least partially dependent on Monocarboxylate transporters (MCTs) secreted into the culture medium

Summary

Introduction

The Warburg effect demonstrates the importance of glycolysis in the development of primary and metastatic cancers. As the main cell type of tumor vessels, vascular endothelial cells (ECs) play critical roles in angiogenesis and are essential for the growth, proliferation, and migration of cancer cells [4]. Most sporadic RCCs in humans carry inactivating mutations in the VHL tumor suppressor gene, which leads to constitutive stabilization of the hypoxia inducible transcription factors HIF-1α and HIF-2α [10]. These transcription factors activate a cellular response which induces metabolic reprogramming towards aerobic glycolysis and promotes angiogenesis [11]. Identifying the metabolic enzymes that are critical for RCC proliferation and invasion will help develop novel therapeutic targets and enhance the efficacy of common therapeutic agents

Objectives

Methods

Results

Discussion

Conclusion