A Review on Single-Cell analysis of Macrophages in Cancer

Abstract

Cancer is characterized by uncontrolled cell growth and spread into surrounding tissue. According to the North American Association of Central Cancer Registries (NAACCR) and the National Center for Health Statistics, there were 1,918,030 cancer cases and a total of 609,360 deaths estimated in the US in 2022. Although the direct cause of cancer is not fully understood, it is recognized that the immune system plays a major role in the development and progression of tumors. Investigating tumor-associated macrophages (TAMs) is crucial for understanding the immunosuppressive role that they may play in the tumor microenvironment, which makes them a target for immunotherapies to combat cancer. However, angiogenesis, tumor initiation and invasion promoting signals prevent gaining deeper insight into the intricate molecular mechanisms involved in TAMs and the tumor microenvironment. While researchers in the past have used population samples to analyze cells, recent efforts have incorporated single-cell technologies to study the complex mixture of cells in a tumor, monitor the effects of immunotherapies and more. With the revolutionary advent of the first single-cell RNA sequencing (scRNA-seq), researchers have since been able to gain insight into single-cell data with unprecedented accuracy and develop new immunotherapies through different single-cell technologies, such as polymethylsiloxane (PDMS) and Multiplexed Ion Beam Imaging (MIBI) multiplexing. In this review, we underline the benefits of adopting single-cell technologies to identify distinct cell types in complex environments (i.e., tumors) and highlight the potential application of these technologies along with various multiplexing techniques to immunotherapies.