Abstract 190: The anti-cancer potential of thrombospondin-1 by inhibiting angiogenesis and stroma reaction during cervical carcinogenesis
Authors: Wu Ming-Ping , Wu Li-Wha , Chou Cheng-Yang 
Published: May 2015

Introduction: Thrombospondin-1 (TSP-1) is an endogenous angiogenic inhibitor with different biological functions on various cell types. The invasion process of cancers is associated with stroma reaction, which is characterized by fibroblasts activation. Our study was to investigate the role of TSP-1 in angiogenic switch and tumor stroma reaction, which is mainly characterized by fibroblast activation to create a permissive microenvironment for tumor progression.

Material and Methods: Immunohistochemistry was used to check TSP-1 expression and the stroma makers for human surgical specimens. Subcutaneous tumors were generated by inoculating 107 SiHa-vector or SiHa-TSP-1 cells into SCID mice. Matrigel multi-cellular co-culture invasion assay was used to detect the inhibitory ability of TSP-1 on the invasive ability of activated fibroblasts (NIH-3T3) into tumor cells cluster.

Results: The disruption of TSP-1 fence (the expression in basal epithelia) in human surgical specimens occurred concordantly during the transition from low grade squamous intraepithelial lesion (SIL) into high SIL. Meanwhile it was accompanied by an emergence in the upregulation of stroma markers, α-SMA and desmin. Transfection of SiHa cervical cancer cells with a plasmid expressing the TSP-1 exhibited anti-angiogenic activity in vitro, and resulted in reduced tumor growth in SCID mice. It was accompanied by a decrease in tumor vascularization and lower expressions of α-SMA and desmin, as compared with vector controls. Transfection with TSP-1 and purified TSP-1 added to NIH3T3 cells did not alter the protein levels of α-SMA and desmin, but significantly inhibited matrix metalloprotease-2 (MMP-2) activity. Transforming growth factor β (TGF-β), which is a major factor in the fibroblast activation, increased α-SMA and desmin expression, and the ability of cell migration and invasion in NIH3T3 cells. The increased migration ability and the invasive ability into tumor cluster of TGF-β-treated-NIH3T3 cells were dose-dependently inhibited by TSP-1. In contrast, transfection and exogenous addition of TSP-1 in SiHa cells has little effect on the invasive ability of the NIH3T3 cells. Discussion: Our findings suggest that TSP-1 play an inhibitory role in the angiogenic switch during cervical carcinogenesis. Meanwhile, TSP-1 can inhibit tumor stroma reaction that could be attributed to the blockage of activated fibroblasts from invading cancer cells. Our current study demonstrates that TSP-1 plays a broader role in tumor cell biology including the ability to block activated fibroblast (myofibroblasts) migration and invasion, in addition to its well-known anti-angiogenic effects.

Citation Format: Ming-Ping Wu, Li-Wha Wu, Cheng-Yang Chou. The anti-cancer potential of thrombospondin-1 by inhibiting angiogenesis and stroma reaction during cervical carcinogenesis. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 190. doi:10.1158/1538-7445.AM2014-190