Tetraspanin Expression Profile in Soft Tissue Sarcomas

Sarcomas are rare malignant tumors rich in stromal and extracellular material; however, the features involved in their adhesion and cell migration are unclear. Moreover, little is known about molecular alterations, which could contribute to their malignant transformation and biology. We have previously observed a lack of correlation in tetraspanin expression module on sarcomas and a poorer prognosis, using a cDNA microarray platform. Tetraspanins are proteins, which are involved in several cellular processes and their profile, or role in sarcomas is unknown. Our aim was to validate cDNA microarray data and to evaluate the correlation of tetraspanins expression profile with clinical pathological parameters. Protein and transcript expression were evaluated by immunohistochemistry (227 samples) and quantitative real time - PCR (47 samples). Results showed a significant downregulation of CD81 and CD37 transcripts in high grade and metastatic tumors. CD63 showed the highest frequency of cytoplasm protein expression, showing a trend of association with poor survival (p=0,053). CD9 protein was observed, mainly in the membrane of leiomyosarcomas and pleomorphic sarcomas. Taken together, our results indicate that CD9, CD81 and CD82 does appear to play an important role in soft tissue sarcomas prognosis and their higher expression correlates with less aggressive forms of behavior. The role of CD63 protein needs further investigation, due to its high frequency and intensity of expression in STS.