Vassiliki Galani

Increased expression of the bcl6 and CD10 proteins is associated with increased apoptosis and proliferation in diffuse large B-cell lymphomas.

There is increasing evidence that bcl6 and CD10 expression may be related to apoptosis and cell cycle progression. Therefore, 79 cases of de novo diffuse large B-cell lymphomas were studied for the expression of bcl6 and CD10 proteins in relation to 1) the apoptotic index; 2) the proliferation-associated proteins Ki67, cyclin A, and cyclin B1; and 3) the expression of the bcl2, p53, Rb, p16, and p27 proteins. Expression of bcl6, CD10, and bcl2 proteins was found in 54/79 (68%), 28/79 (35%), and 47/74 (63%) cases, respectively. The bcl6/CD10 patterns were as follows: bcl6+/CD10+ (26 cases, 32%), bcl6+/CD10- (28 cases, 33%), bcl6−/CD10− (23 cases, 31%), and bcl6−/CD10+ (2 cases, 4%). Significant positive correlations were found between bcl6/Ki67 (r = .328, P = .003), bcl6/cyclin A (r = .265, P = .018), bcl6/apoptotic index (r = .327, P = .010), CD10/Ki67 (r = .296, P = .008), and CD10/apoptotic index (r = .397, P = .001). In addition, high expression of bcl6 showed significant correlation with negative (null/low) bcl2 expression (χ2 test, P = .002). The above findings indicate that increased expression of the bcl6 and CD10 proteins is associated with increased apoptosis and proliferation in diffuse large B-cell lymphomas. The association between increased bcl6 expression and enhanced apoptosis might be due, at least in part, to the null/low bcl2 expression because previous in vitro data showed that bcl6 overexpression induces apoptosis accompanied by bcl2 and bcl-xl downregulation. Moreover, significant correlation was found between increased apoptotic index and the bcl6+/CD10+ pattern (t test: P = .014, Mann-Whitney test: P = .046). This finding and the positive correlation of the apoptotic index with bcl6 and CD10 expression may be related to previous results showing that the expression of these proteins has favorable effects on the clinical outcome of diffuse large B-cell lymphomas.

Diffuse large B-cell lymphomas with germinal center B-cell-like differentiation immunophenotypic profile are associated with high apoptotic index, high expression of the proapoptotic proteins bax, bak and bid and low expression of the antiapoptotic protein bcl-xl

The aim of this study was to analyze the relations between differentiation immunophenotypes and the status of apoptosis and proliferation in diffuse large B-cell lymphomas. Therefore, the bcl6/CD10/MUM1/CD138 differentiation immunophenotypic profiles were studied in relation to (a) the apoptotic index, (b) the apoptosis-associated bcl2 family proteins bcl2, bcl-xl, bax, bak, bad and bid, (c) the proliferation index (Ki67) and (d) the cell cycle proteins cyclin A, cyclin B1, cyclin D3, cyclin E, p53, Rb, p16 and p27 in 79 cases of diffuse large B-cell lymphomas. Two major differentiation immunophenotypic profiles were distinguished: the germinal center B-cell-like profile; 31 cases (bcl6+/CD10±/MUM1−/CD138−: 29 cases and bcl6−/CD10+/MUM1−/CD138−: two cases) and the nongerminal center B-cell-like profile (bcl6±/CD10−/MUM1+/CD138−); 48 cases. The expression of bax, bak and bid and the apoptotic index were significantly higher in the germinal center B-cell-like profile than in the nongerminal center B-cell-like profile (P=0.045, 0.018, 0.003 and 0.034, respectively). In contrast, the expression of bcl-xl was significantly lower in the germinal center B-cell-like profile than in the nongerminal center B-cell-like profile (P=0.026). The expression of bcl6 and CD10 showed significant positive correlation with the expression of bax (r=0.659, P<0.001 and r=0.240, P=0.033, respectively), bak (r=0.391, P<0.001 and r=0.233, P=0.039, respectively) and bid (r=0.652, P<0.001 and r=0.238, P=0.035, respectively) and significant negative correlation with the expression of bcl-xl (r=−0.536, P<0.001 and r=−0.250, P=0.029, respectively). The expression of MUM1 showed significant negative correlation with the expression of bax (r=−0.276, P=0.014) and bid (r=−0.266, P=0.018) and significant positive correlation with the expression of bcl-xl (r=0.238, P=0.037). The above findings indicate that diffuse large B-cell lymphomas with germinal center B-cell-like immunophenotypic profile are associated with increased apoptosis status, high expression of the proapoptotic proteins bax, bak and bid and low expression of the antiapoptotic protein bcl-xl.

Proliferation profile of classical Hodgkin's lymphomas. Increased expression of the protein cyclin D2 in Hodgkin's and Reed-Sternberg cells

There is accumulating evidence that Hodgkins and Reed–Sternberg cells of classical Hodgkins lymphomas (cHL) display multiple and concurrent alterations in different pathways and checkpoints of the cell cycle. However, the expression of cyclin D2 and its relation to other major cell cycle proteins has not been analyzed in cHL. The aim of the present study was to assess expression of cyclin D2, Ki67, cyclin A, cyclin B1, cyclin D1, cyclin D3, cyclin E, p53, Rb, p16 and p27 proteins in order to gain further insight into the proliferation profile of cHL. Overexpression of cyclin D2 in Hodgkins and Reed–Sternberg cells was detected in 64/89 (72%) cases of cHL. This finding, in view of recent in vitro data showing that constitutive activation of nuclear factor (NF)-kB could upregulate cyclin D2 expression in part via signal transducer and activator of transcription (STAT)-5a, suggests that induction of cyclin D2 expression may support the proliferation of Hodgkins and Reed–Sternberg cells. In addition, the present study showed that (1) increased p27 expression status was significantly correlated with higher levels of cyclin A expression (P=0.048) and (2) increased p53 expression status was significantly correlated with higher levels of cyclin A (P<0.001) and cyclin B1 (P=0.040) expression. The association between increased p27 and p53 expression status and higher expression levels of G2/M cyclins suggests that the impairment of the growth inhibitory activity of the p27 and p53 tumor suppressor pathways may promote the proliferation of Hodgkins and Reed–Sternberg cells.

Blastic Natural Killer (NK)-Cell Lymphoma: Report of an Unusual CD4 Negative Case and Review of the CD4 Negative Neoplasms with Blastic Features in the Literature

Blastic Natural Killer (NK)-cell lymphoma is a relatively new entity which has been recently included in the WHO classification. CD4 expression is observed in most cases of blastic NK-cell lymphomas and has been related with skin tropism. We report an unusual CD4 negative blastic NK-cell lymphoma with primary presentation in the skin, subsequent infiltration of the bone marrow and aggressive behavior. It is emphasized that extensive immunophenotyping and EBER RNA in situ hybridization are required in order to establish the diagnosis of blastic NK-cell lymphoma. We also present a review of the literature with respect to the CD4 negative NK-cell lymphomas with blastic morphological features.

Immunohistological analysis of cell cycle and apoptosis regulators in thymus

The combined expression patterns of cell cycle and apoptosis regulators have not been analyzed in details in human thymus to the best of our knowledge. Our objective was to provide multiparametric and combined immunohistological information regarding the expression levels and the topographical distribution of major cell cycle and apoptosis regulators in postnatal human thymus. Ki67 and cyclins A, B1, D3 and E were frequently expressed by thymocytes with higher expression in cortical than medullary thymocytes. The expression of cyclin D2 was low in thymocytes. Thymic epithelial cells (TEC) exhibited low expression of Ki67 and cyclins. Bid was frequently expressed by thymocytes, Bcl-xL by cortical thymocytes and Bcl-2 by medullary thymocytes. The expression levels of Bim and survivin in thymocytes were low. The expression levels of Bax and Mcl-1 were higher in medullary than cortical thymocytes and TEC. Bak and Bad were mainly expressed in medullary TEC and Hassall Bodies (HB). c-FLIP and Fas were frequently expressed in TEC and FasL was mainly expressed by medullary TEC and HB. Cleaved caspase-3 was expressed by scattered thymocytes at the cortex and the corticomedullary junction and very rarely at the medulla. The different expression profiles and immunotopographical distribution of cell cycle and apoptosis regulators in thymocytes and TEC indicate that their expression is tightly regulated during thymic cell differentiation and that they are differentially involved in the cell survival/death regulation of thymocytes and TEC. Furthermore, this study indicates decrease of the proliferation and caspase-dependent apoptosis of thymocytes from the cortex to the medulla.

Expression of cell cycle and apoptosis regulators in thymus and thymic epithelial tumors

The human thymus supports the production of self-tolerant T cells with competent and regulatory functions. Various cellular components of the thymic microenvironment such as thymic epithelial cells (TEC) and dendritic cells play essential roles in thymic T cell differentiation. The multiple cellular events occurring during thymic T cell and TEC differentiation involve proteins regulating cell cycle and apoptosis. Dysregulation of the cell cycle and apoptosis networks is involved in the pathogenesis of thymic epithelial tumors (TET) which are divided into two broad categories, thymomas and thymic carcinomas. The present review focuses on the usefulness of the analysis of the expression patterns of major cell cycle and apoptosis regulators in order to gain insight in the histophysiology of thymus and the histopathology, the clinical behavior and the biology of TET.

Immunohistological Analysis of the Jun Family and the Signal Transducers and Activators of Transcription in Thymus

The Jun family and the signal transducers and activators of transcription (STAT) are involved in proliferation and apoptosis. Moreover, c-Jun and STAT3 cooperate to regulate apoptosis. Therefore, we used double immunostaining to investigate the immunotopographical distribution of phospho-c-Jun (p-c-Jun), JunB, JunD, p-STAT3, p-STAT5, and p-STAT6 in human thymus. JunD was frequently expressed by thymocytes with higher expression in medullary compared to cortical thymocytes. p-c-Jun was frequently expressed by cortical and medullary thymic epithelial cells (TEC) and Hassall bodies (HB). p-STAT3 was frequently expressed by TEC with higher expression in cortical compared to medullary TEC and HB. p-c-Jun, JunB, p-STAT3, p-STAT5, and p-STAT6 were rarely expressed by thymocytes. JunB and JunD were expressed by rare cortical TEC with higher expression in medullary TEC. p-STAT5 and p-STAT6 were expressed by rare cortical and medullary TEC. Double immunostaining revealed p-c-Jun and JunD expression in rare CD11c positive dendritic cells. Our findings suggest a notable implication of JunD in the physiology of thymocytes and p-c-Jun and p-STAT3 in the physiology of TEC. The diversity of the immunotopographical distribution and the expression levels of p-c-Jun, JunB, JunD, p-STAT3, p-STAT5, and p-STAT6 indicates that they are differentially involved in the differentiation of TEC, thymocytes, and dendritic cells.