Cyclin D1 positive multiple myeloma: Predominance of the short, 3′UTR-deficient transcript is associated with high cyclin D1 mRNA levels in cases with t(11;14) translocation, but does not correlate with proliferation rate or genomic deletions

Cyclin D1 expression in Rosai-Dorfman disease: A near constant finding that is not invariably associated with MAPK/ERK pathway activation

Activating mutations in the MAPK/ERK pathway have been shown in nearly half of cases of Rosai-Dorfman disease (RDD). Cyclin D1, a key cell cycle regulator, constitutes a major downstream target of the MAPK/ERK pathway. In this study, we aim to further understand the pathogenesis of RDD by assessing the lesional histiocytes for cyclin D1, p-ERK, Ki-67 and BCL2 by immunohistochemistry We assessed 35 samples of RDD and a control group of histiocyte-rich reactive lesions. Cyclin D1 was expressed in about 90% of cases of RDD. Cyclin D1 was positive in 25-95% (median, 85%) of lesional histiocytes, was moderately/strongly expressed in 97% of cyclin D1-positive cases, and was significantly higher than in control specimens. p-ERK was positive in 16 of 30 (53%) cases of RDD and was negative in all controls. Whereas all p-ERK-positive RDD cases had concurrent cyclin D1 expression, over a third of cyclin D1-positive cases were negative for p-ERK. Ki-67 was low in RDD (median, 3%). BCL-2 was positive in lesional histiocytes in nine of 10 RDD cases assessed and was negative Overall, these findings point to unexpected, potential roles of these molecules in the pathogenesis of RDD. Overexpression of cyclin D1 in the absence of ERK phosphorylation in a subset of RDD cases opens the possibility of oncogenic mechanisms bypassing ERK, and supports the notion that cyclin D1 overexpression in RDD is multifactorial. Moreover, the observed lack of correlation between cyclin D1 with Ki-67 proliferative index suggests that prosurvival actions of cyclin D1 are, at least in part, cell-cycle independent. Finally, expression of BCL-2 and the low Ki-67 index suggest that RDD might be driven by anti-apoptotic rather than pro-proliferative oncogenic mechanisms.

Comprehensive and quantitative analysis of G1 cyclins. A tool for studying the cell cycle

In eukaryotes, the cell cycle is driven by the actions of several cyclin dependent kinases (CDKs) and an array of regulatory proteins called cyclins, due to the cyclical expression patterns of the latter. In yeast, the accepted pattern of cyclin waves is based on qualitative studies performed by different laboratories using different strain backgrounds, different growing conditions and media, and different kinds of genetic manipulation. Additionally, only the subset of cyclins regulating Cdc28 was included, while the Pho85 cyclins were excluded. We describe a comprehensive, quantitative and accurate blueprint of G₁ cyclins in the yeast Saccharomyces cerevisiae that, in addition to validating previous conclusions, yields new findings and establishes an accurate G₁ cyclin blueprint. For the purposes of this research, we produced a collection of strains with all G₁ cyclins identically tagged using the same and most respectful procedure possible. We report the contribution of each G₁ cyclin for a broad array of growing and stress conditions, describe an unknown role for Pcl2 in heat-stress conditions and demonstrate the importance of maintaining the 3’UTR sequence of cyclins untouched during the tagging process.

Post-transcriptional Modifications Contribute to the Upregulation of Cyclin D2 in Multiple Myeloma

PURPOSE

Dysregulation of one of the three D-cyclin genes has been observed in virtually all multiple myeloma tumors. The mechanisms by which CCND2 is upregulated in a set of multiple myeloma are not completely deciphered. We investigated the role of post-transcriptional regulation through the interaction between miRNAs and their binding sites at 3'UTR in CCND2 overexpression in multiple myeloma.

EXPERIMENTAL DESIGN

Eleven myeloma cell lines and 45 primary myeloma samples were included in the study. Interactions between miRNAs deregulated in multiple myeloma and mRNA targets were analyzed by 3'UTR-luciferase plasmid assay. The presence of CCND2 mRNA isoforms different in length was explored using qRT-PCR, Northern blot, mRNA FISH, and 3' rapid amplification of cDNA ends (RACE)-PCR.

RESULTS

We detected the presence of short CCND2 mRNA, both in the multiple myeloma cell lines and primary cells. The results obtained by 3'RACE experiments revealed that changes in CCND2 3'UTR length are explained by alternative polyadenylation. The luciferase assays using plasmids harboring the truncated CCND2 mRNA strongly confirmed the loss of miRNA sites in the shorter CCND2 mRNA isoform. Those multiple myelomas with greater abundance of the shorter 3'UTR isoform were associated with significant higher level of total CCND2 mRNA expression. Furthermore, functional analysis showed significant CCND2 mRNA shortening after CCND1 silencing and an increased relative expression of longer isoform after CCND1 and CCND3 overexpression, suggesting that cyclin D1 and D3 could regulate CCND2 levels through modifications in polyadenylation-cleavage reaction.

CONCLUSIONS

Overall, these results highlight the impact of CCND2 3'UTR shortening on miRNA-dependent regulation of CCND2 in multiple myeloma.

The impact of cyclin D1 mRNA isoforms, morphology and p53 in mantle cell lymphoma: p53 alterations and blastoid morphology are strong predictors of a high proliferation index

BACKGROUND

Mantle cell lymphoma is a clinically heterogeneous disease characterized by overexpression of cyclin D1 protein. Blastoid morphology, high proliferation, and secondary genetic aberrations are markers of aggressive behavior. Expression profiling of mantle cell lymphoma revealed that predominance of the 3'UTR-deficient, short cyclin D1 mRNA isoform was associated with high cyclin D1 levels, a high "proliferation signature" and poor prognosis.

DESIGN AND METHODS

Sixty-two cases of mantle cell lymphoma were analyzed for cyclin D1 mRNA isoforms and total cyclin D1 levels by real-time reverse transcriptase polymerase chain reaction, and TP53 alterations were assessed by immunohistochemistry and molecular analysis. Results were correlated with proliferation index and clinical outcome.

RESULTS

Predominance of the short cyclin D1 mRNA was found in 14 (23%) samples, including four with complete loss of the standard transcript. TP53 alterations were found in 15 (24%) cases. Predominance of 3'UTR-deficient mRNA was significantly associated with high cyclin D1 mRNA levels (P=0.009) and more commonly found in blastoid mantle cell lymphoma (5/11, P=0.060) and cases with a proliferation index of >20% (P=0.026). Both blastoid morphology (11/11, P<0.001) and TP53 alterations (15/15, P<0.001) were significantly correlated with a high proliferation index. A proliferation index of 10% was determined to be a significant threshold for survival in multivariate analysis (P=0.01).

CONCLUSIONS

TP53 alterations are strongly associated with a high proliferation index and aggressive behavior in mantle cell lymphoma. Predominance of the 3'UTR-deficient transcript correlates with higher cyclin D1 levels and may be a secondary contributing factor to high proliferation, but failed to reach prognostic significance in this study.

Plasma cell myeloma and related neoplasms

Session 1 of the 2009 Workshop of the Society for Hematopathology/European Association of Haematopathology, Cleveland, OH, focused on plasma cell neoplasms. This report summarizes the salient diagnostic, clinical, and genetic features of plasma cell myeloma (PCM) and related neoplasms. Based on the cases submitted to the workshop, we highlight common diagnostic issues and unusual manifestations of plasma cell neoplasms, such as t(11;14)+ PCM, plasma cell leukemia, and nonsecretory plasmacytoma, as well as plasmablastic transformation of PCM. Additional issues repeatedly raised at the workshop included the differential diagnosis of extramedullary dissemination of PCM vs primary extramedullary plasmacytoma and plasmablastic lymphoma; systemic plasma cell neoplasms in immunocompromised people; and Epstein-Barr virus-associated plasma cell neoplasms. Difficult cases with borderline features presented by submitters emphasized the necessity of integrating clinical, immunophenotypic, and genetic features for appropriate classification of these disorders.

Differential diagnosis of cyclin D2+ mantle cell lymphoma based on fluorescence in situ hybridization and quantitative real-time-PCR

Mantle cell lymphoma is characterized by the t(11;14) chromosomal translocation, resulting in the overexpression of cyclin D1 (CycD1). Recently, cases of mantle cell lymphoma negative for cycD1 but positive for cycD2 or cycD3 were identified by gene expression profiling and confirmed by immunohistochemistry. We analyzed 4 cases of cycD2(+) mantle cell lymphoma with a translocation involving the CCND2 locus, and its differential diagnosis from 35 mature B-cell non-Hodgkin's lymphomas based on immunohistochemistry, quantitative RT-PCR and FISH analysis. Bona fide cycD2(+) mantle cell lymphoma carried translocations involving the CCND2 gene, and IGH and IGK loci were identified as partners. As a result of this translocation, cycD2 mRNA was highly over-expressed when compared with normal lymphoid tissue and other B-cell non-Hodgkin's lymphomas, including chronic lymphocytic leukemia, making this technique ideally suited to identify cycD2(+)mantle cell lymphoma. In contrast, positive immunostaining for cycD2 was found in most B-cell non-Hodgkin's lymphomas, and therefore, it is not specific for a diagnosis of cycD2(+)mantle cell lymphoma.

Multiple recurrent chromosomal breakpoints in mantle cell lymphoma revealed by a combination of molecular cytogenetic techniques

Mantle cell lymphoma (MCL) is genetically characterized by 11q13 translocations leading to the overexpression of CCND1, and additional secondary genomic alterations that may be important in the progression of this disease. We have analyzed 22 MCL cases and 10 MCL cell lines using multicolor fluorescence in situ hybridization (M-FISH), FISH, and comparative genomic hybridization (CGH). The 19 cases with abnormal karyotype showed the t(11;14)(q13;q32) translocation and, additionally, 89% of cases showed both numerical (n = 58) and structural (n = 77) aberrations. All but one MCL cell line showed t(11;14) and structural and numerical alterations in highly complex karyotypes. Besides 11 and 14, the most commonly rearranged chromosomes were 1, 8, and 10 in the tumors and 1, 8, and 9 in the cell lines. No recurrent translocations other than the t(11;14) were identified. However, we identified 17 recurrent breakpoints, the most frequent being 1p22 and 8p11, each observed in four cases and two cell lines. Interestingly, five tumors and four cell lines displayed a complex t(11;14), cryptic in one case and two cell lines, preferentially involving chromosome 8. In typical MCL, ATM gene deletions were significantly associated with a high number of structural and numerical alterations. In conclusion, MCL does not have recurrent translocations other than t(11;14), but shows recurrent chromosomal breakpoints. Furthermore, most MCL harbor complex karyotypes with a high number of both structural and numerical alterations affecting several common breakpoints, leading to various balanced and unbalanced translocations.

Specific lentiviral shRNA-mediated knockdown of cyclin D1 in mantle cell lymphoma has minimal effects on cell survival and reveals a regulatory circuit with cyclin D2

Cyclin D1 overexpression is the hallmark of mantle cell lymphoma (MCL). However, the importance of cyclin D1 in the maintenance and progression of the disease remains to be defined. The aim of this study was to elucidate the role of cyclin D1 overexpression using an efficient cyclin D1-shRNA and a lentiviral system in well-characterized MCL cell lines. Surprisingly, the knockdown of cyclin D1 led to a moderate retardation in growth, without induction of apoptosis. The cyclin D1-shRNA-transduced MCL cells showed a 15% shift from S phase to G(1) phase of the cell cycle, a weak induction of p27(Kip1), decreased Rb (Ser807/811) phosphorylation, and a consistent upregulation of cyclin D2 mRNA and protein expression. However, double knockdown of cyclins D1 and D2 did not intensify the effects observed with cyclin D1 knockdown alone. These data suggest that the moderate effects of cyclin D1 downregulation on survival and proliferation are likely the result of compensatory cyclin-independent mechanisms governing proliferation or alternatively, secondary genetic events that make cyclin D1 dispensable. These findings have important implications for MCL therapy, as strategies targeting only cyclin D1 function might be hampered by compensatory regulatory mechanisms, resulting in a low probability of treatment response.