Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0079731 (B-cell lymphoma)
 16,671 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cross-linking surface immunoglobulin (Ig)M on the WEHI-231 B-cell lymphoma results in decreased cell size, G1/S growth arrest, and finally DNA cleavage into oligonucleosomal fragments that are the classical features of apoptotic cells. Treatment of WEHI-231 cells with anti-IgM in early G1 phase prevents phosphorylation of the retinoblastoma gene product (pRb) and inhibits entry into S phase. Using unsynchronized cells, we previously demonstrated that cyclin A-associated and Cdk2-dependent GST-pRb kinase activity were inhibited in WEHI-231 cells treated with anti-IgM. We now show that progression of elutriated early G1 phase WEHI-231 cells from early into late G1 phase is accompanied by an increase in the abundance of cyclin A protein and cyclin A-associated kinase activity. Treatment of early G1 cells with anti-IgM prevented this increase in cyclin A-associated kinase activity at late G1, despite minimal changes in the overall level of cyclin A and Cdk2 proteins. Late G1 cells, which already possess high cyclin A-associated kinase activity, were insensitive to anti-IgM treatment and were able to complete the cell cycle. We also found that anti-IgM-treated cells contained increased amounts of the Cdk inhibitor protein p27Kip1. Essentially all of the cyclin A in treated cells was associated with p27, a result which we propose explains the lack of cyclin A/Cdk2 kinase activity. Accumulation of p27 in cyclin A kinase complexes, however, did not decrease the amount of Cdk2 bound to cyclin A. Thus, cross-linking IgM on growth-inhibitable B-cell lymphomas affects cyclin A kinase activity by increasing the levels of p27 in this complex, thus preventing productive pRb phosphorylation and leading to cell cycle arrest and subsequent apoptosis. These results are discussed in terms of the cell cycle restriction points that regulate lymphocyte function, as well as the lineage-specific differences in cell cycle control.
 ...
PMID:Role of cyclin A and p27 in anti-IgM induced G1 growth arrest of murine B-cell lymphomas. 873 99

In the present study, we analysed 34 de novo diffuse large B cell lymphoma (DLCL) from a population-based lymphoma registry for alterations of the RB1 pathway at the genetic (RB1 and CDK4) and protein (pRb, cyclin D1, cyclin D3, CDK4, and E2F-1) level. The results were correlated with the data from our previous studies of CDKN2A deletion and hypermethylation, other p53 pathway components, p27Kip1 expression, and proliferation, as well as with clinical outcome, including prognosis. We found aberrant pRb expression in four (12%) of 34 DLCLs. One of these had a point mutation in intron 3 10 bp downstream of exon 3 generating a novel splice signal. Seven tumours (21%) showed cyclin D3 overexpression, including all three thyroid lymphomas (P = 0.006). Cyclin D3 overexpression and p16INK4A/pRb aberrations were mutually exclusive, supporting an oncogenic role for cyclin D3 in DLCL. p16INK4A inactivation, cyclin D3 overexpression, or aberrant pRb expression was identified in 18 of 34 DLCLs (53%). Combining these results with our previous p53 pathway studies showed that 82% of the de novo DLCLs had alterations of these pathways, and that both pathways were altered in 13 cases (38%). Low E2F-1 expression was associated with treatment failure (P = 0.020), and multivariate analysis of overall survival identified both low E2F-1 expression (relative risk = 6.9; P = 0.0037) and p16INK4A inactivation (relative risk = 3.3; P = 0.0247) as independent prognostic markers. These data support a role of E2F-1 as tumour suppressor gene in lymphoma and strongly suggest that the RB1 and p53 pathways are important in the development of de novo DLCL. Furthermore, low E2F-1 expression and p16INK4A inactivation may serve as prognostic markers for patients with this type of lymphoma.
 ...
PMID:Frequent disruption of the RB1 pathway in diffuse large B cell lymphoma: prognostic significance of E2F-1 and p16INK4A. 1080 23

Primary effusion lymphoma (PEL) represents a peculiar type of B cell lymphoma which associates with HHV-8 infection and preferentially grows in liquid phase in the serous body cavities. In this report, we provide the detailed characterization of a newly established PEL cell line, termed CRO-AP/6. The cell line was obtained from the pleural effusion of a HIV-positive patient with PEL. Its derivation from the tumor clone was established by immunogenotypic analysis. Detailed phenotypic investigations defined that CRO-AP/6 reflects pre-terminally differentiated B cells expressing the CD138/syndecan-1 antigen. Karyotypic studies of CRO-AP/6 identified several chromosomal abnormalities, whereas genotypic studies ruled out the involvement of molecular lesions associated with other types of B cell lymphoma. Both CRO-AP/6 and the parental tumor sample harbored infection by HHV-8. Conversely, EBV infection was present in the parental tumor sample although not in CROAP/6, indicating that CRO-AP/6 originated from the selection of an EBV-negative tumor subclone. The pattern of viral (HHV-8 v-cyclin) and cellular (p27Kip1) regulators of cell cycle expressed by CRO-AP/6, together with the results of growth fraction analysis, point to abrogation of the physiological inverse relationship between proliferation and p27Kip1 expression. Also, both CRO-AP/6 and the parental tumor sample display biallelic inactivation of the DNA repair enzyme gene O6-methylguanine-DNA methyltransferase (MGMT) by promoter methylation. Overall, the CRO-AP/6 cell line may help understand cell cycle control of PEL cells, may clarify the relative contribution of HHV-8 and EBV to the disease growth and development and may facilitate the identification of recurrent cytogenetic abnormalities highlighting putative novel cancer related loci relevant to PEL.
 ...
PMID:Characterization of a novel HHV-8-positive cell line reveals implications for the pathogenesis and cell cycle control of primary effusion lymphoma. 1091 56

Cyclin D3 is the most widely expressed D-type cyclin and can be rate limiting for G1/S transition. To study the expression of cyclin D3 in non-Hodgkin lymphoma, samples from 198 previously untreated patients with lymphoma from a prospectively collected, population-based lymphoma registry were analyzed immunohistochemically for cyclin D3 expression. In 43 lymphomas (21.7%), cyclin D3 was overexpressed. T-cell lymphomas more frequently overexpressed cyclin D3 than B-cell lymphomas. Furthermore, cyclin D3-overexpressing indolent lymphomas were associated with higher proliferation rate, higher p21Waf1 expression, lower p27Kip1 expression, and altered p53. Cyclin D3 overexpression identified a subgroup of patients with indolent B-cell lymphoma with adverse clinical features: patients were older, more frequently had "B" symptoms and extranodal involvement, and were more frequently in the high-intermediate or high-risk International Prognostic Index groups. At univariate analysis of indolent lymphomas, cyclin D3 overexpression was associated significantly with poor overall survival and poor relapse-free survival. The statistical significance was retained on multivariate analysis of overall survival and relapse-free survival. Our results suggest that cyclin D3 is expressed differentially among lymphoma subtypes and that overexpression might identify a subpopulation of patients with indolent lymphoma with adverse clinical features and poor outcome.
 ...
PMID:Cyclin D3 expression in non-Hodgkin lymphoma. Correlation with other cell cycle regulators and clinical features. 1124 97

Cell cycle progression is governed by cyclin dependent kinases (CDK) that are activated by cyclin binding and inhibited by CDK inhibitors. Protein p27Kip1 functions as a CDK inhibitor, which controls the progression from G1 to S phase. Further, p27Kip1 may have a positive regulative influence. In nonneoplastic tissues and in the majority of tumors investigated so far, the immunohistochemical positivity of p27Kip1 showed an inversely proportional relationship to the proliferation index. Among B-cell non-Hodgkin lymphomas, the exceptions to this rule are represented by mantle cell lymphoma, hairy cell leukemia, and the immunoblastic Epstein-Barr virus latent membrane antigen positive diffuse large B-cell lymphoma in AIDS patients. The loss of p27Kip1 expression is a negative prognostic factor in numerous tumors, including the majority of B-cell lymphomas.
 ...
PMID:[Role of p27Kip1 protein in the cell cycle and its appearance in lymphoid tissues, particularly non-Hodgkin's B-cell lymphomas. Review]. 1463 10

S-phase kinase protein 2 (SKP2), an F-box protein, targets cell-cycle regulators including cycle-dependent kinase inhibitor p27KiP1 via ubiquitin-mediated degradation. SKP2 is frequently overexpressed in a variety of cancer cells and has been implicated in oncogenesis; however, its role in diffuse large B-cell lymphoma (DLBCL) has not been elucidated. Therefore, we investigated the role of SKP2 and its ubiquitin-proteasome pathway in a large series (301) of DLBCL patient samples and a panel of DLBCL cell lines. Using immunohistochemistry, SKP2 was detected in 41.6% of DLBCL tumours and was inversely associated with p27Kip1 protein level. The DLBCL subset with high SKP2 and low p27Kip1 showed a strong correlation with the proliferating index marker Ki-67 (p < 0.0001) and also with the germinal centre phenotype (p = 0.0147). Treatment of DLBCL cell lines with bortezomib or expression of SKP2-specific siRNA causes down-regulation of SKP2 and accumulation of p27Kip1, leading to suppression of growth by inducing apoptosis. Furthermore, treatment of DLBCL cells with bortezomib causes apoptosis via involving the mitochondrial pathway and activation of caspases. Finally, treatment of DLBCL cells with bortezomib down-regulated the expression of XIAP, cIAP1, and survivin. Altogether, these results suggest that SKP2 and the ubiquitin-proteasome pathway may be a potential target for therapeutic intervention in DLBCL.
 ...
PMID:S-phase kinase protein 2 is an attractive therapeutic target in a subset of diffuse large B-cell lymphoma. 1885 May 83