The integrin αIIbβ3 was initially believed to be expressed only in cells from the megakaryocytic lineage, such as platelets or HEL cells. In this study, we report for the first time that human prostate carcinoma PC-3 and DU-145 cells express αIIbβ3. Reverse transcription-PCR from HEL (positive control), PC-3, and DU-145 cells amplified a predicted αIIb fragment that hybridized to the full-length αIIb cDNA probe. DNA sequencing of the PCR fragments revealed 100% sequence homology to the corresponding extracellular domain of platelet αIIb but minimal sequence homology to integrins αv or α5. An RNase protection assay was used to confirm the results from reverse transcription-PCR. An antisense riboprobe to αIIb mRNA hybridized to total RNA from HEL, PC-3, and DU-145 cells, suggesting that αIIb mRNA is transcribed in these tumor cells. In situ hybridization on surgical specimens from human prostate tumor tissue stained positive with an antisense riboprobe to αIIb mRNA. The expression of αIIbβ3 protein in PC- 3 and DU-145 cells was demonstrated by Western and dot blotting and flow cytometry with monoclonal antibodies (mAbs) to αIIb (MAB 1990), β3, and αIIbβ3 (AP-2). A protein kinase C activator, phorbol 12-myristate 13- acetate, increased the adhesion of PC-3 cells to PAC-1, a mAb specific to the high-affinity state of αIIbβ3, by more than 80-fold. The invasion of DU- 145 cells through a reconstituted basement membrane was blocked 40-50% by mAbs AP-2 or PAC-1. These data collectively suggest that: (a) prostate tumor cells express αIIbβ3; (b) surface expression of αIIbβ3 integrin is regulated by protein kinase C; and (c) mAbs to this receptor inhibit invasion of prostate cancer cells through a reconstituted basement membrane.
|Original language||English (US)|
|Number of pages||8|
|State||Published - Nov 1 1996|
ASJC Scopus subject areas
- Cancer Research