Expression profile and molecular genetic regulation of cyclin D1 expression in epithelioid sarcoma.

Epithelioid sarcoma is a distinctive, aggressive soft tissue tumor typically presenting as a subcutaneous or deep dermal mass in the distal extremities of young adults. Molecular genetic data of well-characterized cases of epithelioid sarcoma are sparse. A recent cytogenetic study of epithelioid sarcoma by conventional metaphase comparative genomic hybridization reported recurrent gains at chromosome 11q13, a region containing many genes, including the cyclin D1 gene. Cyclin D1 is a positive cell cycle regulator that is overexpressed in a variety of neoplasms, including mantle cell lymphoma and breast carcinoma. The objective of this study was to examine cyclin D1 expression in epithelioid sarcoma. Of 24 cases evaluated, 23 (96%) displayed cyclin D1 nuclear expression using immunohistochemical evaluation. Eight cases, which expressed cyclin D1 by immunohistochemistry, were evaluated by fluorescence in situ hybridization (FISH) and RNA in situ hybridization (RISH) for amplification of the cyclin D1 gene and messenger RNA (mRNA) expression, respectively. Seven of eight cases showed a typical eusomic state. One case showed pseudoamplification due to aneusomy/polysomy. There was no evidence of cyclin D1 gene amplification or messenger RNA overexpression detected by FISH or RNA in situ hybridization analyses, respectively. Our data clearly demonstrate that cyclin D1 protein is upregulated in epithelioid sarcoma, suggesting a role for this cell cycle regulator in the pathogenesis of epithelioid sarcoma. The high level of cyclin D1 protein expression in epithelioid sarcoma appears to be regulated by translational and/or post-translational mechanisms.