Mesenchymal Stem Cells are Recruited and Activated into Carcinoma-Associated Fibroblasts by Prostate Cancer Microenvironment-Derived TGF-β1

Abstract

Tumor stromal cells can supply appropriate signals that may develop aggressive phenotypes of carcinoma cells and establish a complex scenario which culminates in metastasis. Recent works proposed that bone marrow-derived mesenchymal stem cells (MSC) are recruited to primary tumors. However, the exact functions of these cells in the tumor microenvironment are not well characterized, as it is reported that MSC can either promote or inhibit tumor progression. In the present study, we aim at investigating the signaling molecules which regulate the interplay between MSC, prostate carcinoma (PCa) cells and two important cellular types constituting the tumor-associated stroma, macrophages and fibroblasts, during their progression toward malignancy. We identified TGF-β1 as a crucial molecule able to attract MSC recruitment both to PCa cells as well as to tumor stroma components. Moreover, PCa- and tumor stroma-secreted TGF-β1 is important to induce MSC transdifferentiation into carcinoma-associated fibroblast (CAF)-like cells. Consequently, the CAF-like phenotype acquired by MSC is central to promote tumor progression related effects. Thus, tumor-educated MSC enhance PCa invasiveness compared to nonactivated MSC. Additionally, differing from normal MSC, CAF-like MSC perform vascular mimicry and recruit monocytes, which can be further polarized to M2 macrophages within the PCa environment. Our findings indicate a prominent role for TGF-β1 in MSC mobilization and activation strengthened by the fact that the blockade of TGF-β1 signaling impairs MSC promotion of PCa progression. Stem Cells 2016;34:2536-2547.

Skin-derived mesenchymal stem cells as quantum dot vehicles to tumors

“…We successfully simulated directional migration of MSCs toward human breast cancer cells and their conditioned medium in vitro. Our results complement the evidence that MSCs tend to migrate toward cancer cells, 13,18 cancer cell-conditioned medium, 61 and growth medium, supplemented with recombinant proteins found in cancer cell-conditioned medium, 62 verifying that cancer cells secrete molecules promoting MSC migration. The key molecules inducing MSC migration toward tumors supposedly are vascular endothelial growth factor, 63 fibroblast growth factor 2, 64 stromal cell derived factor 1 (SDF-1), 65 chemokine (C-C motif) ligand 2, also known as monocyte chemotactic protein-1, 66 and macrophage migration inhibitory factor.…”

Vasculogenic mimicry signaling revisited: focus on non-vascular VE-cadherin

“…TGF-β1 is involved in MSC differentiation to CAFs which indeed develop VM. Besides, MSC showed tropism with M2 macrophages, that have been related to tumor aggressiveness [81]. …”

Origin of cancer-associated fibroblasts and tumor-associated macrophages in humans after sex-mismatched bone marrow transplantation

“…Recently, multiple independent studies have also implicated bone marrow-derived cells, most likely mesenchymal stem cells, as a considerable source of CAFs 4–13 . Quante et al 10 showed that bone marrow-derived mesenchymal stem cells are actively recruited to the dysplastic stomach, comprising at least 20–25% of αSMA(+) CAFs in a mouse model of inflammation-dependent gastric dysplasia.…”