Beta–microseminoprotein is a prostate protein associated with pterygium

Abstract

Abstract: : Purpose: BMSP or PSP94 is a unique protein associated with prostate cancer, but more generally mucosal tissues. This study has examined the association of this protein with primary pterygium. Methods: All patient procedures received IRB approval and patients signed consent forms. Patient selection required that the pterygium be unilateral, and primary. Tears were collected from both eyes prior surgery, pterygia and control conjunctiva (CC) were collected at the time of surgery and immediately frozen. The analysis consisted of the following: DNA array (Affymetrix U133A, 8 pterygia, controls (3 groups of five)), RT–PCR and real–time PCR using TaqMan Assay on Demand probes employed the same 8 pterygia and pooled (five conjunctiva) controls. Tear samples (2–4 µl from both eyes of 8 patients) were analyzed with SELDI–TOF Protein Chip technology. A US–Bio polycolonal–antibody was used for immunohistochemistry, and western blots (same 8 pterygia tissues used for both). Results: Mass spectrometry of tears prior to surgery revealed a protein (10.7–10.8 Kda) the levels of which were higher in eyes with pterygium (6/8), than in the contralateral eyes. Analysis of expression levels of genes and ESTs that were represented in pterygia and control conjunctiva showed that 28 genes were put into the category of up–regulated. BMSP was found in all samples and up–regulated in 75% of pterygia over CC with an average of 3.45 fold. Density values from gels of RT–PCR products found that BMSP was up–regulated over control CC by 0.6 to 20.74 times and all samples were positive. Real–time PCR showed that in 5/8 pterygium tissues BMSP was up–regulated 3.04 to 5.33 times when compared to control. Western blots showed that the protein was found in all pterygia tissues (n=8). Immunohistochemistry of pterygia tissue showed the presence of the protein in the epithelium, whereas in the control conjunctival tissue little or no positive staining was found. When the antibody was pre–absorbed there was no positive staining. Conclusions: BMSP may be a bio–marker for pterygium or for persistent inflammatory conditions of the ocular surface.

Keywords: proteins encoded by disease genes • Pterygium • conjunctiva