Mesenchymal stem cells and carcinoma-associated fibroblasts sensitize breast cancer cells in 3D cultures to kinase inhibitors

Abstract

Abstract. Stromal cells, such as mesenchymal stem cells (MSCs) and carcinoma-associated fibroblasts (CAFs), play a role in cancer progression. To analyze their ability to modulate drug response, we generated spheroids of MCF-7 or MDA-MB-231 breast cancer cells in the absence or presence of human (h)MSCs or hCAFs and tested the susceptibility of the breast cancer cells to three different kinase inhibitors (TKI258, RAD001 and RAF265) used in cancer therapy. While stromal cells did not affect the response of either breast cancer cell line to the PDGFR/FGFR/VEGFR inhibitor TKI258, they sensitized breast cancer cells to the mTOR inhibitor RAD001. In MCF-7 cells, this was accompanied by increased apoptosis. hMSCs and to a lesser extent hCAFs also enhanced the cytotoxic effect of RAF inhibitor RAF265 on MDA-MB-231 cells. Searching for the mechanism that underlies the effect of stromal cells on RAF265 response we found that stromal cells inhibited RAF265-induced increase in ERK1/2 phosphorylation, supported RAF265-dependent downregulation of PKCα (protein kinase Cα) and prevented RAF265-induced conversion of LC3B, a marker of autophagy. To mimic the changes in ERK1/2 phosphorylation and PKCα expression in response to the stromal cells, we treated cells with MEK1 inhibitor U0126 or PKCα inhibitor Gö6976, respectively. U0126, but not Gö6976, was as effective as hMSCs in sensitizing MDA-MB-231 cells to RAF265. This suggests that hMSCs and hCAFs increased the cytotoxic effect of RAF265 on MDA-MB-231 cells by downregulating ERK1/2 phosphorylation. In summary, this study shows that hMSCs are able to render breast cancer cells more susceptible to kinase inhibitors and that, to the most part, hCAFs to which hMSCs can differentiate are able to mimic the drug-sensitizing effects of hMSCs.

Cancer-Associated Fibroblasts Induce Matrix Metalloproteinase–Mediated Cetuximab Resistance in Head and Neck Squamous Cell Carcinoma Cells

“…Since then, several studies have shown that fibroblasts can induce resistance to various anticancer treatments, such as tamoxifen in the treatment of breast cancer (28,39), gemcitabine and radiotherapy in the treatment of pancreatic adenocarcinoma (26), and paclitaxel in the treatment of non-small cell lung cancer (30). Conversely, fibroblasts may also sensitize tumor cells to therapy as was shown for RAF and MEK1 inhibitors in breast cancer (33). However, the influence of CAFs on the cetuximab treatment response in HNSCC has not previously been investigated.…”

“…CAFs provide protumorigenic signals that lead to increased tumor growth via the stimulation of tumor cell proliferation and angiogenesis as well as the formation of metastases by the enhancement of the migratory and invasive potential of the tumor cells (18)(19)(20)(21)(22)(23)(24)(25). As a number of publications suggest that CAFs could also modulate the drug sensitivity of cancer cells (26)(27)(28)(29)(30)(31)(32)(33)(34), this study was undertaken to evaluate the influence of CAFs on the cetuximab response in HNSCC cell lines.…”

Identification of Tumor Cell- and Stroma Derived Biomarkers of Treatment Response in Head and Neck Cancer

“…CAFs are the major cellular component of the tumor stroma and they have been shown to stimulate tumor growth, 188,194,195 EMT, 184,186,196,197 invasion, 198,199 and metastasis 196,200 and to influence treatment response, by secretion of soluble factors. [203][204][205][206][207][208][209][210][211] The detection of the soluble factors that are responsible for the influence on treatment response could lead to the development of new treatment strategies. However, the crosstalk between cancer cells and CAFs are still not completely understood and the nature of the soluble factors is largely obscure.…”

“…Since then, numerous studies have shown that several different cell types within the tumor stroma, including CAFs, can influence the response to various anti-cancer treatments. [203][204][205][206][207][208][209][210][211] It is now clear that an abnormal stroma contribute to, or even is required for, tumor formation, progression, invasion, and resistance to anti-cancer treatments. 224 One huge disappointment within the stromal targeted therapy area is, as mentioned before, the failure of MPIs.…”

3D multicellular models reflect the efficiency of MSC-directed enzyme/prodrug treatment

“…The report from the mixed 3D cultures with breast cancer cells and the MSC has proven the feasibility of the nodule growth in mixed setup [23]. Detailed analysis suggested that the MSCs rendered the breast cancer cells more susceptible to the kinase inhibitors in the 3D culture conditions.…”