Thrombospondin-1 expression in oral squamous cell carcinomas: correlationswith tumor vascularity, clinicopathological features and survival

Thrombospondin-l (TSP-I) is a 450 kd glycoprotein synthesized and incorpora ted into the extracellular matrix by numerous cell types and reported to su ppress tumor growth and progression by its inhibition of angiogenesis. In o rder to clarify the biological role of TSP-I and determine its clinicopatho logical significance in oral squamous cell carcinomas (SCCs), we identified TSP-I protein expression in 54 oral SCCs by immunohistochemistry and corre lated it with microvessel density (MVD), clinicopathological features and p atient's survival. Thirty-two out of 54 carcinomas (59%) were identified as having a low level of TSP-I expression (TSP-1-L). and 22/54 (41%) carcinom as identified as having a high level of TSP-1 expression (TSP-1-H). The MVD counts (mean +/-S.D. = 9.0+/-4.9) in TSP-I-H tumors was significantly lowe r than that (mean+/-S.D. = 12.7+/-4.4) in TSP-1-H tumors (P = 0.0065). The level of TSP-I expression was not correlated with T category and histologic grade, but inversely correlated with the pattern of tumor invasion (P = 0. 0136) and with lymph nodal status (P = 0.0119). Furthermore, Kaplan-Meier a nalysis showed that the 5-year survival rate of TSP-1-H group was significa ntly higher than that of TSP-1-L group. Our results suggested that TSP-I ex pression exerts an inhibitory effect on tumor vascularity, and that it has value in assessment of aggressiveness and prognosis of oral SCCs. (C) 2000 Elsevier Science Ltd. All rights reserved.