CD49b, CD87, and CD95 Are Markers for Activated Cancer-Associated Fibroblasts Whereas CD39 Marks Quiescent Normal Fibroblasts in Murine Tumor Models

Abstract

Fibroblasts are thought to be key players in the tumor microenvironment. Means to identify and isolate fibroblasts as well as an understanding of their cancer-specific features are essential to dissect their role in tumor biology. To date, the identification of cancer-associated fibroblasts is widely based on generic markers for activated fibroblasts in combination with their origin in tumor tissue. This study was focused on a deep characterization of the cell surface marker profile of cancer-associated fibroblasts in widely used mouse tumor models and defining aberrant expression profiles by comparing them to their healthy counterparts. We established a generic workflow to isolate healthy and cancer-associated fibroblasts from solid tissues, thereby reducing bias, and background noise introduced by non-target cells. We identified CD87, CD44, CD49b, CD95, and Ly-6C as cancer-associated fibroblast cell surface markers, while CD39 was identified to mark normal fibroblasts from healthy tissues. In addition, we found a functional association of most cancer-related fibroblast markers to proliferation and a systemic upregulation of CD87, and CD49b in tumor-bearing mice, even in non-affected tissues. These novel markers will facilitate the characterization of fibroblasts and shed further light in their functions and implication in cancer progression.

Origin and functional heterogeneity of fibroblasts

“…Possible mammary markers of RQFs include the ecto-nucleoside triphosphate diphospohhydrolase 1 (E-NTPDase1)/CD39. 39 Commonly used surface and intracellular markers, largely capturing activated fibroblasts, include PDGFRα/ß (platelet-derived growth factor receptor-alpha and -beta), podoplanin, CAV1 (caveolin 1), DDR2 (discoidin domain receptor 2), FAP F I G U R E 1 Developmental origin and plasticity of fibroblasts. A, Developmental origin of fibroblasts.…”

Application of ATAC-Seq for genome-wide analysis of the chromatin state at single myofiber resolution

“…Similarly, Resistin ( Retn ) and Cd45 were used as markers for adipocytes and hematopoietic cells, respectively (40, 41). The cell Surface Antigen Thy1 was the marker selected for fibroblasts (42). In addition, Lymphocyte antigen 6a ( Ly6a ) and Adhesion G protein-coupled receptor E1 ( ADGRE1 ) were selected for fibro/adipogenic progenitors (FAPs) and macrophages, respectively (43, 44).…”

Understanding the Role of Fibroblasts following a 3D Tumoroid Implantation for Breast Tumor Formation

“…They also play a vital role in intra- or inter-cell communications to regulate a normal tissue microenvironment, in addition to their support in the immune system at the tissue level (more information in paragraph 2 of Section 3.6 ) [ 22 , 26 ]. The relatively high expression of CD39 usually differentiates fibrocytes from quiescent normal fibroblasts [ 23 , 27 ]. The reversible conversion of fibroblasts to fibrocytes takes place at a cellular level, as per the need to maintain the cellular integrity and tissue function [ 27 , 28 ].…”

“…Their support in EMT transition leads to tumor stemness, and drug resistance as mentioned above ( Figure 2 ) [ 58 , 69 , 70 , 71 ]. CAFs reprogram the regulatory molecules, and change the metabolic pathways to favor the tumor growth ( Figure 3 ) [ 23 ]. They not only represent the predominant cell component in the tumor but also secrete the major extracellular proteins or fibers that are needed for the formation of tumor stroma ( Figure 2 and Figure 3 ).…”

“…Interestingly, active or proliferating cancer cells are present predominantly in the outer margin of tumor tissue [ 16 , 20 , 21 ], while cancer-associated fibroblasts (CAFs) primarily occupy the core part rather than the outer growing tumor region [ 17 , 18 , 19 , 20 ]. In addition, the percentage ratio of CAFs to cancer cells is significantly more towards the core region, with a reversed ratio in the outer region of a tumor tissue, as represented by the Figure 2 [ 4 , 16 , 22 , 23 ]. On the one hand, the cancer core, because of less blood and nutrition supply, is usually the detective core which represents the positive charge topological area that is occupied mostly by round fibroblasts.…”