Ectopic expression of platelet integrin αIIbβ3 in tumor cells from various species and histological origin

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Abstract
The integrin αIIbβ3 is a membrane receptor which was considered to be expressed only in cells of megakaryocytic lineage. We have shown that αIIbβ3 is expressed in mouse melanoma B16a cells, and in human prostate adenocarcinoma cells. The purpose of this study was to determine whether the megakaryocytic product αIIbβ3 was functionally expressed in other non-megakaryocyte lineage tumor cells. By using the reverse transcription polymerase chain reaction (RT-PCR), we have obtained data demonstrating that αIIbβ3 is expressed in a variety of tumor cell lines (17) derived from different species (human, rat and mouse) and of different histological origins (skin, blood, lung, liver, kidney, cervix, colon, bladder, breast and prostate). Immunostaining of tumor cells with a monoclonal antibody (MAb) to αIIbβ3 demonstrates that αIIbβ3 protein is also expressed in tumor cells. A protein kinase C activator PMA stimulates adhesion of tumor cells to fibronectin and fibrinogen, and this stimulated adhesion is blocked by a function-blocking MAb directed to αIIbβ3. Our results indicate that the megakaryocytic gene product αIIbβ3 integrin is widely expressed among tumor cells of non-megakaryocytic lineage, suggesting that ectopic expression of this integrin may play an important role in tumor progression. Int. J. Cancer 72:642–648, 1997.