Overall survival in aggressive B-cell lymphomas is dependent on the accumulation of alterations in p53, p16, and p27.

Different studies have already shown that the isolated inactivation of p21, p16, or p27 cyclin-dependent kinase inhibitors (CKIs) is associated with increased growth fraction, tumor progression, or decreased overall survival in cases of non-Hodgkin's lymphoma. In this study we linked molecular study of the p53 and p16 genes with immunohistochemical analysis of p27 expression in a group of aggressive B-cell lymphomas [large B-cell lymphomas (LBCLs) and Burkitt's lymphomas]. This was done to analyze the relationship between p53 and p16 silencing, p27 anomalous overexpression, and clinical follow-up, testing the hypothesis that the accumulation of CKI alterations could confer to the tumors a higher aggressivity. In a group of 62 patients, p53 inactivation as a result of mutation was observed in 11 cases (18%) and p16 silencing was seen in 27 cases (43.5%) as a result of methylation (20 of 62), 9p21 deletion (7 of 44), or p16 mutation (2 of 62). The simultaneous inactivation of p53 and p16 was detected exclusively in five LBCL cases. Anomalous expression of p27, which has been proven to be associated with the absence of p27/CDK2 complexes and the formation of p27/cyclin D3 complexes where p27 is inactivated, was detected in 19 of 61 cases (31%). Cases characterized by p27 anomalous expression display concurrent inactivation of p21 (provided by p53 mutations) and/or p16 CKIs in 11 of 14 LBCL cases (P = 0.040). When the relationship between the association of inactivated CKIs and overall survival was considered, a significant relationship was found between a lower overall survival probability and an increased number of inactivated CKIs in LBCL cases, with the worst prognosis for the cases displaying concurrent p53, p16, and p27 alterations. This proves that simultaneous inactivation of different tumor suppressor pathways does indeed take place, and that tumor aggressiveness takes advantage of this CKI-concerted silencing. In this same series of data, Burkitt's lymphoma patients seem to behave in a different way than LBCLs, with p53 and p16 alteration being mutually exclusive and the association with p27 anomalous expression not being clinically significant. These facts seem to support that the additive effect of the inactivation of different CKIs could be dependent of the histological type.

Unique phenotypic profile of monocytoid B cells: differences in comparison with the phenotypic profile observed in marginal zone B cells and so-called monocytoid B cell lymphoma.

Monocytoid B cells (MBCs) are a subset of B cells that may be recognized in several reactive and tumoral lymph node conditions, including toxoplasmic lymphadenitis, infectious mononucleosis, and Hodgkin's lymphoma. Although this is a commonly observed cell population, which has even given its name to a type of lymphoma, MBC lymphoma, scarcely any information is available about the function and characteristics of this cell type. A relationship with marginal zone (MZ) B lymphocytes has been claimed for MBCs, but this has not yet been fully proven. Indeed, specific markers for MBCs are still lacking, which has made it difficult to analyze their relationship with other B cell subpopulations and confirm the existence of tumors deriving from this B cell subset. We used a panel of cell cycle markers to explore the characteristics of MBCs and their relationship with MZ B cells, nodal MZ lymphoma, and splenic MZ lymphoma. We therefore compared the phenotypic profile of MBCs in different conditions with normal MZ B cells within the spleen and mesenteric lymph nodes, with a group of seven cases of nodal MZ/MBC lymphoma and another group of five cases of splenic MZ lymphoma. MBCs were mainly in the G(0) to G(1) phases, as deduced from the presence of a proportion of between 10 and 35% Ki67-positive cells, whereas very low expression was observed with cyclin A and cyclin B staining. Nests of MBCs were clearly labeled by the expression of p21(WAF1), a cyclin-dependent kinase inhibitor (CKI), rarely detectable in benign lymphocytes, and by cyclin E. Basically all MBCs were bcl-2-negative, and high cyclin D2 and cyclin D3 were also detected in these cells, at proportions and intensities above expected levels, when the percentage of proliferating cells was taken into account. p27(KIP1) expression was characterized by homogeneous reactivity, higher than that observed in other B cell populations with a relatively high-growth fraction. Immunoglobulin staining showed undetectable light and heavy chains. However, splenic MZ cells, nodal MZ lymphoma, and splenic MZ lymphoma showed a distinct expression of IgM and bcl-2, with high p27 (KIP1) nuclear expression and undetectable or low levels of cyclin A, B, E, or D, or p21(WAF1) expression. The data from this study show an unexpected immunophenotype in MBCs, different from the one observed in splenic and lymph node MZ B cells. This suggests that either MBCs are a unique B cell population from a distinct cell lineage, or if related to MZ cells, they would represent a definite differentiation stage characterized by a distinctive immunophenotype. They also show so-called MZ/MBC lymphoma to be more closely related to lymph node and splenic MZ B cells, as they do not share the most distinctive features of MBCs.

CD44v6 expression in inflammatory bowel disease is associated with activity detected by endoscopy and pathological features.

AIMS: Overexpression of CD44v6 in colon crypt epithelial cells has been suggested to have diagnostic potential in differentiating ulcerative colitis from other forms of colon inflammation, including Crohn's disease. Our aim was to determine the value of CD44v6 expression in inflammatory bowel disease (IBD) and to look for possible associations between CD44v6 expression and activity of this disease. METHODS AND RESULTS: CD44v6 expression was studied using immunohistochemical techniques in 100 surgical and endoscopic colon samples of ulcerative colitis (n = 71) and Crohn's disease (n = 29), and in every case disease activity was studied by endoscopy and microscopic examination. Fifty-five of 71 (77.5%) samples of ulcerative colitis showed monoclonal antibody 2F10 stained colon epithelium, as did 16 of 29 (55.2%) samples of Crohn's disease. CD44v6 was detected in 88.2% (15 of 17) of cases of IBD with severe disease activity and in 100% of eight cases of severe ulcerative colitis. Our study showed a strong association between CD44v6 expression and the activity of IBD (P = 0.007). CONCLUSIONS: CD44v6 expression in IBD is significantly associated with activity detected by means of endoscopy and pathological features. Our data suggest that CD44v6 expression may have some usefulness in conjunction with other factors as a means of evaluating the disease activity. Moreover, CD44v6 expression was higher in ulcerative colitis than Crohn's disease (P = 0.02), although this does not confirm the utility of monoclonal antibody 2F10 in differential diagnosis between ulcerative colitis and Crohn's disease, as there was a notable percentage of positive samples of Crohn's disease.

Anomalous high p27/KIP1 expression in a subset of aggressive B-cell lymphomas is associated with cyclin D3 overexpression. p27/KIP1-cyclin D3 colocalization in tumor cells.

p27 cyclin-dependent kinase inhibitor downregulation is essential for transition to the S phase of the cell cycle. Thus, proliferating cells in reactive lymphoid tissue show no detectable p27 expression. Nevertheless, anomalous high p27 expression has been shown to be present in a group of aggressive B-cell lymphomas with high proliferation index and adverse clinical outcome. This suggests that abnormally accumulated p27 protein has been rendered functionally inactive. We analyzed the causes of this anomalous presence of p27 in a group of aggressive B-cell lymphomas, including 54 cases of diffuse large B-cell lymphomas and 20 Burkitt's lymphomas. We simultaneously studied them for p27, cyclin D3, cyclin D2, cyclin D1, and cyclin E expression, because it has been stated that high levels of expression of cyclin D1 or E lead to increased p27 levels in some cell types. A statistically significant association between p27 and cyclin D3 expression was found for the group as a whole. Additionally, when dividing the cases according to the level of expression of cyclin D3 by reactive germinal centers, it was observed that cases with stronger cyclin D3 expression also show higher p27 expression. The relationship between both proteins was also shown at a subcellular level by laser confocal studies, showing that in cases with high expression of both proteins there was a marked colocalization. Additional evidence in favor of p27 sequestration by cyclin D3 was provided by coimmunoprecipitation studies in a Burkitt's cell line (Raji) showing the existence of cyclin D3/p27 complexes and the absence of CDK2/p27 complexes. These results could support the hypothesis that there are cyclin D3/p27 complexes in a subset of aggressive B-cell lymphomas in which p27 lacks the inhibitory activity found when it is bound to cyclin E/CDK2 complexes. This interaction between both proteins could lead to an abnormal nuclear accumulation, detectable by immunohistochemical techniques.

Loss of p16 protein expression associated with methylation of the p16INK4A gene is a frequent finding in Hodgkin's disease.

p16 protein binds and inactivates cyclin D-CDK4/6 complexes, stopping the cell cycle at the G1/S boundary. Loss of p16 expression is found frequently in human cancer tissues, often resulting from allelic loss or promoter region hypermethylation in non-Hodgkin's lymphomas. Hodgkin's disease has been shown to be a monoclonal neoplasm of B-cells in which a majority of cells are cycling. In the attempt to identify hypothetical CDK inhibitor inactivation that could explain the accumulation of proliferating cells, we decided to focus on the p16INK4A gene. To determine whether inactivation of this gene is implicated in the development of Hodgkin's disease, we immunostained 40 cases with a monoclonal antibody for the p16 protein. At the same time, we used a methylation-specific PCR technique to determine the methylation status of exon 1 of the p16INK4A gene in 23 cases in this series. Loss of p16 expression was found in 30 of 37 cases (absence of expression in most Hodgkin's/Reed-Sternberg cells, with a normal scattered pattern of p16 expression in the reactive background). Only seven samples showed nuclear p16 expression in a significant proportion of large tumoral cells. In agreement with this finding, hypermethylation of p16INK4A gene was found in 14 of 23 cases by PCR. All the p16 cases found positive by immunohistochemistry also showed unmethylated DNA. These results show that loss of p16 protein expression is usually observed in Hodgkin's/Reed-Sternberg cells in Hodgkin's disease, frequently associated with p16INK4A gene hypermethylation. The high frequency of abnormal methylation found in this study suggests that this genetic event may play an important role in the pathogenesis of the disease.

Loss of p16/INK4A protein expression in non-Hodgkin's lymphomas is a frequent finding associated with tumor progression.

The CDKN2A gene located on chromosome region 9p21 encodes the cyclin-dependent kinase-4 inhibitor p16/INK4A, a negative cell cycle regulator. We analyzed p16/INK4A expression in different types of non-Hodgkin's lymphoma to determine whether the absence of this protein is involved in lymphomagenesis, while also trying to characterize the genetic events underlying this p16/INK4A loss. To this end, we investigated the levels of p16/INK4A protein using immunohistochemical techniques in 153 cases of non-Hodgkin's lymphoma, using as reference the levels found in reactive lymphoid tissue. The existence of gene mutation, CpG island methylation, and allelic loss were investigated in a subset of 26 cases, using single-strand conformational polymorphism and direct sequencing, Southern Blot, polymerase chain reaction, and microsatellite analysis, respectively. Loss of p16/INK4A expression was detected in 41 of the 112 non-Hodgkin's lymphomas studied (37%), all of which corresponded to high-grade tumors. This loss of p16/INK4A was found more frequently in cases showing tumor progression from mucosa-associated lymphoid tissue low-grade lymphomas (31 of 37) or follicular lymphomas (4 of 4) into diffuse large B-cell lymphomas. Analysis of the status of the p16/INK4A gene showed different genetic alterations (methylation of the 5'-CpG island of the p16/INK4A gene, 6 of 23 cases; allelic loss at 9p21, 3 of 16 cases; and nonsense mutation, 1 of 26 cases). In all cases, these events were associated with loss of the p16/INK4A protein. No case that preserved protein expression contained any genetic change. Our results demonstrate that p16/INK4A loss of expression contributes to tumor progression in lymphomas. The most frequent genetic alterations found were 5'-CpG island methylation and allelic loss.

Clinical outcome in diffuse large B-cell lymphoma is dependent on the relationship between different cell-cycle regulator proteins.

PURPOSE: The goal of this work was to perform a comprehensive exploration of the relationship between the clinical outcome of diffuse large B-cell lymphoma (DLBCL) and the expression of a panel of tumor suppressor and oncogenic proteins, which includes some cell-cycle regulator proteins involved in the p53 pathway. PATIENTS AND METHODS: To this end, we collected the clinical data of 141 patients with DLBCL and immunohistochemically analyzed diagnostic tumoral tissue from each patient for the presence of Ki67 (MIB1, Immuno-tech, Marseille, France), bcl2, p53, p21/WAF1, MDM2, and retinoblastoma (Rb) proteins. RESULTS: The results show that several proteins are associated with some of the clinical traits analyzed. Multivariate analysis showed that an extended overall survival (OS) time was associated with low growth fraction, high Rb protein, and low MDM2 expression, as well as with known clinical parameters. The probability of inducing a complete remission (CR) was only associated with clinical parameters, although univariate study showed that a low growth fraction was associated with a higher probability of inducing a CR. Univariate study of disease-free survival (DFS) showed that tumors with high bcl2 expression and nodal origin have a shorter DFS time, although multivariate study only confirmed the adverse effect of bcl2 expression. CONCLUSION: Taking all these results into consideration, it seems that although the overall outcome for patients with DLBCL is decided by a combination of different clinical and biologic variables, the expression of some of these cell-cycle regulator proteins appears to be specifically associated with the different clinical features of tumors.

Expression of p21WAF1/CIP1 in fetal and adult tissues: simultaneous analysis with Ki67 and p53.

AIMS: To determine the expression of p21WAF1/CIP1 in relation to the expression of Ki67 and p53 in various normal adult and fetal tissues, and to investigate its distribution throughout the cell cycle. METHODS: The expression of p21WAF1/CIP1 in relation to Ki67 and p53 was analysed in adult and fetal tissues using immunohistochemical techniques. Heat induced epitope retrieval techniques were used to characterise the presence of p21WAF1/CIP1 in different tissues, as well as to detect its distribution throughout the cell cycle. In addition, flow cytometry and western blotting were used to test whether the level of p21WAF1/CIP1 expression varied at different phases of the cell cycle in phytohaemagglutinin (PHA) stimulated lymphocytes. RESULTS: p21WAF1/CIP1 expression varied from one tissue to another, and it was restricted mainly to the squamous and glandular epithelium, where it appeared in association with p53. Human tissues in which p21WAF1/CIP1 was found showed a mutually exclusive topographical sequential expression between p21WAF1/CIP1 and Ki67. This was confirmed by double labelling studies, which showed that p21WAF1/CIP1 positive cells were in the G0 phase. Unlike these findings of a decline in p21WAF1/CIP1 expression after the G0 phase, PHA stimulated lymphocytes showed a level of p21WAF1/CIP1 expression that rose as the cell progressed through the cell cycle. CONCLUSIONS: The analysis of p21WAF1/CIP1 expression in relation to the status of p53 should take into account the existence of variable p21WAF1/CIP1 expression in different tissues. This could provide an explanation for the varying frequency of p53 mutations in tumours of different cellular origin. In tissues characterised by regular p21WAF1/CIP1 expression, it appears in a pattern that is consistent with the proposed role of this inhibitor of cyclin dependent kinases in cell cycle arrest-that of inducing cell differentiation. The conflicting results of in vivo and in vitro studies could support the hypothesis that microenvironmental conditions may influence the location of p21WAF1/CIP1 in different phases of the cell cycle.

Cyclin-dependent kinase inhibitor p27KIP1 in lymphoid tissue: p27KIP1 expression is inversely proportional to the proliferative index.

Cell cycle progression is regulated by the combined action of cyclins, cyclin-dependent kinases (CDKs), and CDK inhibitors (CDKIs). p27KIP1, which has a high degree of similarity with p21WAF1, is a general CDKI thought to be involved in G1 arrest in response to agents that inhibit cell cycle progression. The aims of this study were 1) to establish the pattern of expression of p27KIP1 protein in nontumor lymphoid tissue, 2) to determine whether p27KIP1 is involved in lymphomagenesis, and 3) to address the possible relationship between p27KIP1 and p21WAF1 expression in reactive and tumor lymphoid tissue. p27KIP1 protein was found to be mainly present in quiescent lymphocytes in reactive lymphoid tissue as well as in peripheral blood lymphocytes, with an inverse expression for p27KIP1 and Ki-67 proteins. The same p27KIP1 expression pattern was observed in lymphomas, independently of histological type; small resting cells were p27KIP1 positive, and large proliferating cells were p27KIP1 negative. Therefore, tumors with a low proliferative index were mostly positive, whereas tumors characterized by a higher growth fraction bad low p27KIP1 protein levels. An unexpected finding was the existence of a group of six cases of high-grade lymphomas (three diffuse large B-cell lymphomas and three Burkitt's lymphomas) with homogeneously strong staining for p27KIP1 protein. All 6 of these cases belong to a group of 28 cases characterized by blockage of the p53 tumor suppressor pathway, as determined by genetic (p53 mutation) or immunophenotypic studies (p53+/p21-). p27KIP1 expression was not seen in any case of aggressive non-Hodgkin's lymphoma with an intact p53 pathway. The results indicate that p27KIP1 is down-regulated in lymphomas with a high proliferative index, although it is highly expressed in high-grade lymphomas with defects in the p53 pathway.

Widespread cutaneous necrosis and antiphospholipid antibodies: two episodes related to surgical manipulation and urinary tract infection.

Widespread cutaneous necrosis (WCN) associated with antiphospholipid antibodies is rare. Its mechanisms have yet to be elucidated, and there are no well-established guidelines for its management. We describe a woman who had two episodes of WCN related to surgical manipulation for urinary tract obstruction and urinary tract infection. Lupus anticoagulant was always positive. In the second episode anticardiolipin antibodies were elevated, and protein C levels were temporarily decreased. We found only ten previously reported cases of WCN associated with antiphospholipid antibodies, none of which were related to surgical manipulation.