Background: As tumor cells spread beyond their primary site they undergo changes in their gene expression that may be detectable and useful for microstaging. The cancer/testis (CT) antigens are a family of proteins that include MAGE 1-3, NY-ESO-1, SSX 1-5, and others that are potential markers for microstaging melanoma. CT antigens are produced by many tumor types but few normal tissues other than testis. One CT antigen, CTp11, was shown to be expressed by metastasizing melanoma cell lines but not by nonmetastasizing variants. We tested this finding by studying the expression of CTp11 and NY-ESO-1 by melanoma samples from different stages of progression.
Materials and methods: We collected 20 primary, 22 locoregional, and 10 distant metastatic melanoma samples. We extracted total RNA, and reverse transcription yielded cDNA, which was PCR-amplified using primers to detect beta-actin, tyrosinase, MART-1, NY-ESO-1, and CTp11. The PCR products were separated on ethidium bromide-stained agarose gels and visualized by UV transillumination.
Results: All samples were positive for beta-actin and MART-1 and all but two were positive for tyrosinase, confirming RNA integrity and the presence of melanoma. Twenty-seven samples were positive for NY-ESO-1, CTp11, or both. CTp11 tended to be expressed by primary melanomas and NY-ESO-1 by metastatic samples (P < 0.02).
Conclusions: There is a statistically significant difference in the distribution of the expression of CTp11 and NY-ESO-1 in melanoma from different stages of progression. NY-ESO-1 may be a marker of more advanced disease and CTp11 of less advanced disease.
Copyright 2001 Academic Press.