Immunohistochemical detection of the 150-kDa oxygen-regulated protein in bladder cancer.

OBJECTIVE

To investigate the relationship between the expression of the 150-kDa oxygen-regulated protein (ORP150, which functions as a molecular chaperone in the endoplasmic reticulum for the folding and trafficking of newly synthesized proteins) and the aggressiveness of bladder cancer, and the expression of vascular endothelial growth factor (VEGF) and matrix metalloproteinases (MMPs), as the former is a secreting protein through the endoplasmic reticulum and the latter are closely involved in tumour invasion.

MATERIALS AND METHODS

Thirty-nine cystectomy specimens, comprising 12 superficial (pT1) and 27 invasive (pT2-pT4) tumours, were immunohistochemically analysed using antibodies against ORP150, VEGF, MMP-1, MMP-2 and MMP-9. Staining was scored from 0 to 3, according to the ratio of positively staining cells.

RESULTS

Staining was positive (score 1-3) for ORP150 in 10 of 12 superficial and 25 (93%) of the invasive tumours, with a significantly higher staining score for stage T4 than stage T1 tumours. The trend was the same for the staining score of MMP-2, and there was a significant correlation between ORP150 and MMP-2 expression.

CONCLUSIONS

The expression of ORP150 was common in bladder cancer, with a tendency for greater expression in higher stages. The significant correlation between ORP150 and MMP-2 expression suggests that ORP150 acts as a molecular chaperone for MMP-2 secretion and thus tumour invasion.