OVER-EXPRESSION OF CYCLIN D1 IN CHRONIC B-CELL MALIGNANCIES WITH ABNORMALITY OF CHROMOSOME 11Q13

Accurate identification of B-cell chronic malignancies is sometimes un certain, despite careful cytologic and immunophenotypic evaluation. Cy togenetics and molecular biology studies may therefore prove useful, b ecause some of these disorders are associated with non-random abnormal ities, such as the t(11;14)(q13;q32) translocation and bcl-1 rearrange ment mainly observed in mantle-cell lymphoma (MCL), We studied the exp ression of cyclin D1 in malignant lymphoid cells from the peripheral b lood of 32 patients with various B-cell chronic lymphoproliferative di sorders, using Northern blot (NB) and RNA in situ hybridization (ISH). Cytogenetic analysis was informative in 18 cases, and most of the mis sing karyotype data were from typical B-CLL cases where a t(11;14) is unlikely to be found. Over-expression of cyclin D1 mRNA was observed b y both NB and ISH in four samples (MCL: two cases; lymphoplasmacytic l ymphoma: one case, unclassified B-cell chronic disorder: one case). In each of these cases there was an abnormality of chromosome 11q13, eit her a t(11;14)(q13;q32) translocation (three cases) or a del(11)(q13) without evidence of chromosome 14 involvement (one case). Cytogenetic and gene rearrangement studies are not available in all institutions a nd have some technical pitfalls. Because of its close association with bcl-1 rearrangement and/or t(11;14), the demonstration of cyclin D1 m RNA over-expression either by NB, or, more conveniently, by ISH, may r epresent additional information which could be of help for the identif ication of B-cell malignancies.