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Tumor Discovery

REVIEW ARTICLE
Monocytes in tumor: The perspectives of

single-cell analysis

Xin Fu and Mingzhu Yin*
Department of Dermatology, Huan Engineering Research Center of Skin Health and Disease,
Hunan Key Laboratory of Skin Cancer and Psoriasis, Xiangya Hospital, Central South University,
Changsha, Hunan 410008, China

Abstract

Infiltration of mononuclear phagocytes into the tumor microenvironment (TME)
is known to orchestrate the tumor progression and is generally considered to
interfere with the efficacy of immune checkpoint blockade therapies. For a more
precise definition of monocytes, we review some recent advances in the functions of
monocytes and macrophages in TME based on single-cell analysis. We also summarize
the details of the different subpopulations of monocytes and macrophages involved
in immunotherapy and their potential applications in clinical studies. In this review,
we briefly introduce the developmental trajectory of mononuclear phagocytes,
including monocytes, tumor-associated macrophages, dendritic cells and myeloid-
derived suppressive cells, and their functions in TME. In this review, the potential of
monocytes and their derived cells as diagnostic and therapeutic targets, with regard
to the interaction between monocytes and immune checkpoint therapies, is also
summarized.

Keywords: Monocytes; Single-cell RNA sequencing analysis; Tumor microenvironment;
Tumor-associated macrophages; Dendritic cells
*Corresponding author:
Mingzhu Yin
(yinmingzhu2008@126.com)
Citation: Fu X, Yin M, 2022,
Monocytes in tumor: The 1. Introduction
perspectives of single-cell analysis,
Tumor Discov, 1(1): 4. Monocytes and macrophages are major components of the mononuclear phagocyte
https://doi.org/10.36922/td.v1i1.4 system (MPS), which consists of a wide range of phagocytic cells derived from bone
[1]
Received: December 2, 2021 marrow and yolk sac progenitors . Monocytes differentiate into macrophages and
[2]
Accepted: February 14, 2022 dendritic cells (DCs) in the tumor microenvironment (TME) . Tumor-associated
Published Online: March 10, 2022 macrophages (TAMs) are abundant in tumor stroma both in mice and humans . Some
[3]
Copyright: © 2022 Author(s). publications have also demonstrated different TAM subtypes and their diverse functions
This is an Open Access article in tumor progression [4,5] . Previous studies have shown that monocytes/macrophages are
distributed under the terms of the
Creative Commons Attribution important regulators of tumor progression.
License, permitting distribution,
and reproduction in any medium, As an important component of TME, monocytes are probably thought to be closely
provided the original work is related to the efficacy of immune checkpoint blockade (ICB) immunotherapy. Several
properly cited. studies have revealed that monocytes express programmed cell death protein 1 (PD-
-
-
+
Publisher’s Note: AccScience 1), and that CD14 CD16 HLA DRhi monocytes could be potential indicators for
Publishing remains neutral with responsiveness to ICB therapy . To study monocytes that infiltrate into tumor tissue, a
[6]
regard to jurisdictional claims in
published maps and institutional universal nomenclature and classification system is needed to ease the demonstration
affiliations. of further related findings about monocytes. There are a few reliable markers on the cell
Volume 1 Issue 1 (2022) 1 https://doi.org/10.36922/td.v1i1.4