The protein expression of TRP-1 and galectin-1 in cutaneous malignant melanomas

Patients with metastazing malignant melanoma have a poor outcome and determination of thickness of the primary tumor remains as the most important prognostic predictor. The aim of this study was to use an antibody-based proteomics strategy to search for new molecular markers associated with melanoma progression. Two proteins, TRP-1 and galectin-1, were identified as proteins with enhanced expression in cells from the melanocytic lineage.

Protein profiling of TRP-1 and galectin-1 together with proliferation marker Ki-67 and melanocyte marker Melan-A was performed in normal tissues from 144 individuals and in 216 different tumors using tissue microarrays and immunohistochemistry. The protein expression pattern was further analyzed in a defined cohort of 157 patients diagnosed with invasive cutaneous malignant melanoma.

Both TRP-1 and galectin-1 were highly expressed in normal melanocytes and melanoma. The expression of TRP-1 was inversely correlated with tumor stage (p=0.002, (R=-0.28)). Neither TRP-1 or galectin-1 was associated with overall or disease free survival (p>0.14, p>0.46 respectively). Ki-67 was associated with tumor stage and survival (p<0.001).

TRP-1 and galectin-1 protein expression patterns were determined in normal and cancer tissues and both proteins were expressed in the majority of the malignant melanomas. There was no correlation between TRP-1 or galectin-1 expression and survival.