Invasion of uterine cervical squamous cell carcinoma cells is facilitated by locoregional interaction with cancer-associated fibroblasts via activating transforming growth factor-beta

Objective. Local invasion is a common pattern of spread in uterine cervical squamous cell carcinoma (CSCC). Although transforming growth factor-beta (TGF-beta) facilitates invasion of various types of cancer cells, the role of the TGF-beta pathway in CSCC is unclear. In this study, we analyzed the role of TGF-beta signaling in the progression of CSCC. Methods. Immunohistochemistry was used to examine the expression of TGF-beta pathway molecules in 67 CSCC samples with clinicopathological data. Activation of the TGF-beta pathway was investigated following co-culture of CSCC cells and cervical cancer-associated fibroblasts (CCAFs). Results. Clinicopathological analysis of CSCC samples revealed that prominent expression of TGF-beta receptor-2 was more frequent in CSCC with lymphovascular space invasion (LVSI) than without LVSI (p <0.01). Lymph node metastasis was more frequent in cases in which phosphorylated SMAD3 (pSMAD3) was localized exclusively.at the boundary of tumor clusters (n = 9, p < 0.05). Recombinant TGF-beta 1 increased pSMAD3 expression and enhanced cellular invasion (p <0.005) in CSCC cells, which was attenuated by an inhibitor of the TGF-beta receptor (p < 0.005). Enhanced pSMAD3 expression and invasion was also observed when conditioned media from CSCC cells co-cultured with CCAFs were administered. Luciferase assays showed that this medium contained a large amount of active TGF-beta. Along with TGF-beta activation, thrombospondin-1 was upregulated in both CSCC cells and CCAFs, while thrombospondin-1 silencing in either CSCC cells or CCAFs repressed the activity of TGF-beta. Thrombospondin-1 was prominently expressed in cases with pSMAD3 boundary staining (p <0.05). Conclusions. These results suggest that interaction between CSCC cells and surrounding CCAFs activates TGF-beta via thrombospondin-1 secretion to facilitate CSCC invasion. (C) 2014 Elsevier Inc. All rights reserved.