Untargeted metabolomics reveals distinct metabolic reprogramming in endothelial cells co-cultured with CSC and non-CSC prostate cancer cell subpopulations.

Anusha Jayaraman,Timothy M Thomson,Silvia Marin,Francesca Mateo,Marta Cascante,Josep J Centelles,Praveen Kumar,Stewart F Graham,Pedro De Atauri,Daotai Nie

doi:10.1371/journal.pone.0192175

Abstract

Tumour angiogenesis is an important hallmark of cancer and the study of its metabolic adaptations, downstream to any cellular change, can reveal attractive targets for inhibiting cancer growth. In the tumour microenvironment, endothelial cells (ECs) interact with heterogeneous tumour cell types that drive angiogenesis and metastasis. In this study we aim to characterize the metabolic alterations in ECs influenced by the presence of tumour cells with extreme metastatic abilities. Human umbilical vein endothelial cells (HUVECs) were subjected to different microenvironmental conditions, such as the presence of highly metastatic PC-3M and highly invasive PC-3S prostate cancer cell lines, in addition to the angiogenic activator vascular endothelial growth factor (VEGF), under normoxia. Untargeted high resolution liquid chromatography-mass spectrometry (LC-MS) based metabolomics revealed significant metabolite differences among the various conditions and a total of 25 significantly altered metabolites were identified including acetyl L-carnitine, NAD+, hypoxanthine, guanine and oleamide, with profile changes unique to each of the experimental conditions. Biochemical pathway analysis revealed the importance of fatty acid oxidation and nucleotide salvage pathways. These results provide a global metabolic preview that could help in selectively targeting the ECs aiding in either cancer cell invasion or metastasis in the heterogeneous tumour microenvironment.

Highlights

Tumour microenvironment is a perfectly designed niche for cancer cells, in that they have acquired the ability to break all the cellular rules and hijack the stromal cells for their survival and propagation [1]
We report differential responses of Endothelial cells (ECs) to heterogeneous tumour cell subpopulations, using Human umbilical vein endothelial cells (HUVECs) which were co-cultured with prostate cancer cell sub-populations exhibiting extreme metastatic abilities
For this purpose we have used a dual model cell lines derived from the PC3 cells [12], in which the PC-3M is enriched with epithelial cancer stem cell (CSC) properties, Fig 1

Summary

Introduction

Tumour microenvironment is a perfectly designed niche for cancer cells, in that they have acquired the ability to break all the cellular rules and hijack the stromal cells for their survival and propagation [1]. Endothelial cells (ECs), like other stromal cells such as cancer-associated fibroblasts and macrophages, can be reprogrammed by tumourreleased factors inducing angiogenesis [2]. Tumour-released factors can significantly affect the ECs downstream angiogenic signalling, i.e. at the level of cellular metabolism suggesting that they may be attractive targets for anti-cancer therapy [4]. In order to understand the metabolic changes that affect angiogenesis associated with tumours it is important to choose a method that can focus only on the affected ECs, which is different in vivo due to the complexity associated with extracting different types of stromal cells from the tumour tissues. The in vitro co-culture method employed in this study intends to explore the tumour-endothelial cell association. Metabolic changes due to this stromal-tumour cellular interaction are yet to be explored

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