Thrombospondin (TSP-1) is a 450-kd adhesive
glycoprotein that was initially discovered in platelets and subsequently in a variety of cell types. Several reports suggest that
TSP-1 possesses tumour suppressor function, through its ability to inhibit tumour neovascularization. In this study we investigated tissue sections from 124
breast carcinomas for the immuno-histochemical expression of
TSP-1 protein and its relationship to several clinicopathological parameters. The possible relationship to
hormone receptors content, p53
protein, proliferation associated indices, angiogenesis,
VEGF expression and extracellular matrix components (
tenascin,
fibronectin,
laminin,
collagen type IV and
syndecan-1) was also estimated.
TSP-1 was detected in the perivascular tissue, at the epithelial-stromal junction, in the stroma and in the tumour cells. High tumour cell
TSP-1 expression was observed in 9.7%, moderate in 17.7%, mild in 10.5%, while 62.1% of the cases were negative for
TSP-1 expression. The survival analysis showed an increased risk of recurrence associated with low
TSP-1 tumour cell expression. High stromal
TSP-1 expression was observed in 3.2% of the cases, moderate in 3.3%, mild in 27.4%, while 63.6% of the cases showed absence of
TSP-1 expression. This expression was higher in invasive lobular type of
breast cancer and inversely correlated with the lymph node involvement and the
estrogen receptor content. Stromal
TSP-1 expression was also positively correlated with extracellular matrix components expression,
tenascin,
fibronectin,
collagen type IV,
laminin, and
syndecan-1. The relationship of
TSP-1 expression with
tumor angiogenesis, growth fraction and p53
protein expression was not significant. Our data suggest that
TSP-1 expression seems to be associated with favorable
biological behavior and may have clinical value in terms of predicting the risk of recurrence. In addition,
TSP-1 might not be a direct anti-
angiogenic factor, although it seems to be implicated in the remodeling of
breast cancer tissue through interaction with other extracellular matrix components.