Cyclin D1 expression in patients with multiple myeloma.

INTRODUCTION Chromosomal abnormalities are detected in 50 to 70% of patients with multiple myeloma (MM). By conventional cytogenetic analysis, a t(11;14)(q13;q32) is observed at a frequency of 3 to 14%. MATERIALS AND METHODS To demonstrate a cyclin D1 expression in MM patients or MM cell lines, 14 patients with multiple myeloma (MM) and nine human multiple myeloma cell lines (HMCL) were screened by a competitive RT-PCR and/or Northern blot analysis for cyclin D1 expression. Furthermore, we screened 10 MM patients with FISH to demonstrate a relationship between the cyclin D1 expression and the presence of the t(11;14). RESULTS Five HMCL had a cyclin D1 overexpression: three of them had a t(11;14)(q13;q32) and two had extra copies of chromosome 11. A cyclin D1 expression was found at diagnosis in seven out of 14 untreated MM patients (50%). Out of 14 MM patients, FISH studies were performed in 10 patients. A t(11;14) was detected in three out of 10 patients and extra copies of chromosome 11 were found in two additional patients. CONCLUSION Cyclin D1 expression is a common event in MM patients (50%) and is associated either with a t(11;14)(q13;q32) or extra copies of chromosome 11. The prognostic role of the cyclin D1 expression and the level of this expression, as compared to other B-cell chronic lymphoproliferative disorders such as mantle cell lymphoma or hairy cell leukemia, remains to be determined in the pathogenesis of multiple myeloma.