Immunohistochemical analysis of cyclin D1 shows deregulated expression in multiple myeloma with the t(11;14)

The t(11;14)(q13;q32) chromosomal translocation, the hallmark of mantle cel l lymphoma (MCL), is recurrently found in multiple myelomas (MM) by means o f conventional cytogenetics. Unlike MCL, recent molecular studies of MM-der ived cell lines with t(11;14) have indicated that the breakpoints are highl y dispersed over the 11q13 region; however, the fact that cyclin D1 is gene rally overexpressed in these cell lines suggests that this gene is the targ et of the translocation. To evaluate further the involvement of cyclin D1 i n MM, we used immunohistochemistry and fluorescence in situ hybridization t o investigate cyclin D1 expression and the presence of chromosome 11 abnorm alities In a representative panel of 48 MM patients (40 at diagnosis and 8 at relapse), Cyclin D1 overexpression occurred in 12/48 (25%) of cases; com bined, immunohistochemistry and fluorescence in situ hybridization analyses in 39 patients showed cyclin D1 positivity in all of the cases (7/7) beari ng the t(11;14), in two of the 13 cases with trisomy 11, and in one of the 19 cases with no apparent abnormalities of chromosome 11, Our data indicate that the t(11;14) translocation in MM leads to cyclin D1 overexpression an d that immunohistochemical analysis may represent a reliable means of ident ifying this lesion in MM.