Background: Centrocytic/mantle cell lymphoma (MCL) is characterized by a specific chromosomal translocation, t(11;14)(q13;q32), which leads to deregulated expression of the G1 cyclin, cyclin D1 (PRAD1, CCND1, BCL1). Cyclin D1 overexpression has been demonstrated in MCL at the mRNA level by Northern blotting and at the protein level by both Western blotting and immunoperoxidase staining.
Patients and methods: To assess the utility of in situ hybridization (ISH) to detect cyclin D1 mRNA expression in formalin-fixed, paraffin embedded tissue, five MCL specimens from three patients and two cases of B-cell small lymphocytic lymphoma (B-SLL) were studied. BCL1 major translocation cluster gene rearrangements had been previously documented in two MCL patients; the other MCL and the two B-SLL, showed no detectable BCL1 or cyclin D1 rearrangements.
Results: ISH was performed using anti-sense 3H-labeled RNA probes for the cyclin D1 3' untranslated region (pPL7) and partial cyclin D1 cDNA (pPL8). ISH experiments using an anti-sense actin RNA probe demonstrated adequate RNA preservation in all cases. Each of five specimens of MCL demonstrated increased cyclin D1 mRNA. In contrast, neither of the two cases of B-SLL demonstrated detectable levels.
Conclusions: Overexpression of cyclin D1 mRNA can be detected in MCL by ISH using formalin fixed paraffin embedded tissue. The ISH technique may be useful in diagnosing and classifying low-grade B-cell lymphomas and should be applicable to the study of cyclin D1 mRNA expression in a broad spectrum of lymphoid proliferations and solid tumors.