PLoS One. 2013 Jul 26;8(7):e68923. doi: 10.1371/journal.pone.0068923.

Cancer-associated fibroblasts promote proliferation of endometrial cancer cells.

Subramaniam KS, Tham ST, Mohamed Z, Woo YL, Mat Adenan NA, Chung I.

Department of Pharmacology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia.

 

Abstract

Endometrial cancer is the most commonly diagnosed gynecologic malignancy worldwide; yet the tumor microenvironment, especially the fibroblast cells surrounding the cancer cells, is poorly understood. We established four primary cultures of fibroblasts from human endometrial cancer tissues (cancer-associated fibroblasts, CAFs) using antibody-conjugated magnetic bead isolation. These relatively homogenous fibroblast cultures expressed fibroblast markers (CD90, vimentin and alpha-smooth muscle actin) and hormonal (estrogen and progesterone) receptors. Conditioned media collected from CAFs induced a dose-dependent proliferation of both primary cultures and cell lines of endometrial cancer in vitro (175%) when compared to non-treated cells, in contrast to those from normal endometrial fibroblast cell line (51%) (P<0.0001). These effects were not observed in fibroblast culture derived from benign endometrial hyperplasia tissues, indicating the specificity of CAFs in affecting endometrial cancer cell proliferation. To determine the mechanism underlying the differential fibroblast effects, we compared the activation of PI3K/Akt and MAPK/Erk pathways in endometrial cancer cells following treatment with normal fibroblasts- and CAFs-conditioned media. Western blot analysis showed that the expression of both phosphorylated forms of Akt and Erk were significantly down-regulated in normal fibroblasts-treated cells, but were up-regulated/maintained in CAFs-treated cells. Treatment with specific inhibitors LY294002 and U0126 reversed the CAFs-mediated cell proliferation (P<0.0001), suggesting for a role of these pathways in modulating endometrial cancer cell proliferation. Rapamycin, which targets a downstream molecule in PI3K pathway (mTOR), also suppressed CAFs-induced cell proliferation by inducing apoptosis. Cytokine profiling analysis revealed that CAFs secrete higher levels of macrophage chemoattractant protein (MCP)-1, interleukin (IL)-6, IL-8, RANTES and vascular endothelial growth factor (VEGF) than normal fibroblasts. Our data suggests that in contrast to normal fibroblasts, CAFs may exhibit a pro-tumorigenic effect in the progression of endometrial cancer, and PI3K/Akt and MAPK/Erk signaling may represent critical regulators in how endometrial cancer cells respond to their microenvironment.

PMID: 23922669

 

Supplements:

Fibroblasts in the Endometrium: Friend or Foe?

Ivy Chung, Ph.D.

Endometrial cancer remains the most common gynecologic malignancy in the United States with an estimate of 45,000 cases in recent years.  Importantly, the incidence and mortality rates for endometrial cancer have been rising in the developed and developing countries, an observation closely associated with the obesity epidemic.  Although the five-year survival for endometrial cancer is >85%, a subset of endometrial tumors exhibits aggressive phenotype, characterized by high histological grade, regional lymphovascular invasion and distant metastasis.  The prognosis for such tumors is relatively poor, with the five-year survival range from 16-66%.

We are interested in understanding the role of fibroblasts in endometrial cancer progression. In the normal female reproductive tract, fibroblasts can promote epithelial development and differentiation.  They are responsible for extracellular matrix remodeling and producing paracrine growth factors that control cell proliferation, survival and death. Here, we showed that fibroblasts isolated from endometrial cancer (cancer-associated fibroblasts) can induce proliferation of primary and endometrial cancer cell lines.  Interestingly, fibroblasts from benign endometrium showed contrasting effects – tumor inhibitory action.  The different secretory factors from normal and cancer-associated fibroblasts may explain the opposing effects by these fibroblasts – this aspect remains to be investigated thoroughly.  Nevertheless, our study indicates that fibroblast population within the endometrium can be targeted in treating women with aggressive endometrial cancer.

Ivy Chung-fig1

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