Methodology of determining the metabolomic profile of tumor-associated macrophages and monocytes in oncological diseases

Abstract

Breast cancer is the leading cause of cancer-related death among women worldwide. Tumor-associated macrophages (TAMs) constitute the primary component of innate immunity in breast cancer tissue. During the development of new approaches for breast cancer treatment aimed at editing the epigenome of TAM, precise methods for the analysis of macrophage metabolome are required to examine the effect on new approaches on macrophage metabolism. Our study aimed to develop an HPLC-MS/MS-based analytical approach to characterize the metabolome of human innate immune cells (TAMs and their precursors, monocytes). Analysis of lipid extracts was conducted on a Dionex UltiMate 3000 liquid chromatograph connected to a Maxis Impact qTOF mass analyzer with an ESI ion source. Quantitative analysis of 38 amino acids in the cells was conducted using the Jasem Amino Acids LC-MS/MS Analysis Kit and an HPLC-MS/MS chromatographic system consisting out of an Agilent 6460 triple quadrupole mass spectrometric detector (Agilent), and an Agilent 1260 II liquid chromatograph (Agilent ) with Amino acids-HPLC Column (Jasem). The modified Folch method with double extraction was found to be the optimal approached for the sample preparation, since it enables to simultaneously isolate the lipid extract and water-soluble substances, in particular, amino acids. The method of reversed-phase chromatography yielded more useful data on the cell lipid composition than the method of hydrophilic interaction liquid chromatography (HILIC). The minimum number of cells required to determine the metabolome of immune system cells (TAM and monocytes) was identified as 2 × 106. Thus, we have developed the approach to determine the lipid and amino acid composition of modelled human TAMs and primary monocytes isolated out of breast cancer patients using minimal amount of clinical material.