Carcinoma associated fibroblasts (CAFs) promote breast cancer motility by suppressing mammalian Diaphanous-related formin-2 (mDia2)

Abstract

The tumor microenvironment (TME) promotes tumor cell invasion and metastasis. An important step in the shift to a pro-cancerous microenvironment is the transformation of normal stromal fibroblasts to carcinoma-associated fibroblasts (CAFs). CAFs are present in a majority of solid tumors and can directly promote tumor cell motility via cytokine, chemokine and growth factor secretion into the TME. The exact effects that the TME has upon cytoskeletal regulation in motile tumor cells remain enigmatic. The conserved formin family of cytoskeleton regulating proteins plays an essential role in the assembly and/or bundling of unbranched actin filaments. Mammalian Diaphanous-related formin 2 (mDia2/DIAPH3/Drf3/Dia) assembles a dynamic F-actin cytoskeleton that underlies tumor cell migration and invasion. We therefore sought to understand whether CAF-derived chemokines impact breast tumor cell motility through modification of the formin-assembled F-actin cytoskeleton. In MDA-MB-231 cells, conditioned media (CM) from WS19T CAFs, a human breast tumor-adjacent CAF line, significantly and robustly increased wound closure and invasion relative to normal human mammary fibroblast (HMF)-CM. WS19T-CM also promoted proteasome-mediated mDia2 degradation in MDA-MB-231 cells relative to control HMF-CM and WS21T CAF-CM, a breast CAF cell line that failed to promote robust MDA-MB-231 migration. Cytokine array analysis of CM identified up-regulated secreted factors in WS19T relative to control WS21T CM. We identified CXCL12 as a CM factor influencing loss of mDia2 protein while increasing MDA-MB-231 cell migration. Our data suggest a mechanism whereby CAFs promote tumor cell migration and invasion through CXCL12 secretion to regulate the mDia2-directed cytoskeleton in breast tumor cells.

Targeting the mDia Formin-Assembled Cytoskeleton Is an Effective Anti-Invasion Strategy in Adult High-Grade Glioma Patient-Derived Neurospheres

“…Invasion was weak and amoeboid shaped cells detached from the neuro-sphere itself. mDia inhibition via expression of dominant negative constructs or siRNA, or treatment with SMIFH2 induced amoeboid morphological conversions in a variety of epithelial cancers, including ovarian, prostate, breast and hepatocarcinoma [19,20,21,24,40,41,42]. One possible explanation for this morphological conversion is that, with disrupted mDia dynamic activation, RhoA/ROCK1 contractility/disruption of cell-cell adhesions may be favored [43,44], thereby leading to sustained leading-edge contraction, which drives cellular extrusion.…”

“…mDias also associate with, and stabilize, the microtubule cytoskeleton [16]. We and others validated targeting mDia as an anti-invasive cancer therapy in in vitro GBM, breast, ovarian, and colon human cancer models [7,17,18,19,20,21].…”

Loss of DIAPH3, a Formin Family Protein, Leads to Cytokinetic Failure Only under High Temperature Conditions in Mouse FM3A Cells

“…The dysregulated expression of Diaph3 has been observed in various cancer cells and is associated with cancer malignancy [ 47 , 48 , 49 ]. As mentioned above, Diaph3 appears to be involved in the regulation of microtubule stability in cell division.…”

The Signaling Duo CXCL12 and CXCR4: Chemokine Fuel for Breast Cancer Tumorigenesis

“…It enhances invasiveness of TNBC cells via ERK1/2 activation [ 97 ]. Furthermore, CXCL12 boosts TNBC cells migration via cytoskeletal rearrangements [ 98 ]. These effects can be blocked by a specific CXCR4 inhibitor, suggesting that disrupting the interactions with tumor microenvironment might be a promising therapeutic strategy for TNBC that lacks a targeted treatment [ 97 ].…”