Christina Economopoulou

The Role of BCL2 Family of Apoptosis Regulator Proteins in Acute and Chronic Leukemias

The disturbance of apoptosis molecular signaling pathways is involved in carcinogenesis. BCL2 family of proteins is the hallmark of apoptosis regulation. In the last decade, new members of BCL2 gene family were discovered and cloned and were found to be differentially expressed in many types of cancer. BCL2 protein family, through its role in regulation of apoptotic pathways, is possibly related to cancer pathophysiology and resistance to conventional chemotherapy. It is well known that leukemias are haematopoietic malignancies characterized by biological diversity, varied cytogenetics, different immunophenotype profiles, and diverse outcome. Current research focuses on the prognostic impact and specific role of these proteins in the pathogenesis of leukemias. The understanding of the molecular pathways that participate in the biology of leukemias may lead to the design of new therapies which may improve patients survival. In the present paper, we describe current knowledge on the role of BCL2 apoptosis regulator proteins in acute and chronic leukemias.

Phosphatidylinositol 3′-Kinase Catalytic Subunit α Gene Amplification Contributes to the Pathogenesis of Mantle Cell Lymphoma

Purpose: Activation of phosphatidylinositol 3′-kinase pathway is implicated in the pathogenesis of mantle cell lymphoma (MCL). The genetic change in phosphatidylinositol 3′-kinase catalytic subunit α (PIK3CA) in MCL has not been identified. Experimental Design: Thirty-five primary MCL cases and 2 MCL cell lines (GRANTA-519 and Rec-1) were used to investigate somatic mutation and gene copy number of PIK3CA. Gene copy number was determined using quantitative real-time PCR and fluorescence in situ hybridization. We used quantitative real-time reverse transcription-PCR to measure PIK3CA transcription levels. Phosphatase and tensin homologue deleted on chromosome 10 (PTEN) and phoshorylated AKT protein levels were analyzed using Western blotting and immunohistochemistry. Flow cytometry was used to assess apoptosis after treatment of MCL cell lines and one control cell line with LY294002, a specific inhibitor of PI3KCA. Results: Fifteen of 22 (68%) MCL cases and the MCL cell lines harbored a gain (≥3) of PIK3CA gene copy number. In addition, cases with increased PIK3CA gene copy number had elevated PIK3CA mRNA levels. Furthermore, amplification of PIK3CA correlated with the status of AKT phosphorylation in 7 of 12 (58%) primary MCL cases. Inhibition of PIK3CA induced increased apoptosis in the MCL cell lines. PTEN protein expression was present in all 14 primary MCL cases and cell lines by Western blotting, whereas 5 of 33 (15%) cases tested by immunohistochemistry had loss of PTEN expression. Conclusions: We conclude that a gain of gene copy number of PIK3CA is frequent genetic alteration that contributes to MCL progression. PIK3CA is a promising therapeutic target in MCL. (Clin Cancer Res 2009;15(18):5724–32)

Cell cycle and apoptosis regulatory gene expression in the bone marrow of patients with de novo myelodysplastic syndromes (MDS)

Deregulation of cell cycle and apoptosis pathways are known contributors to the pathogenesis of myelodysplastic syndromes (MDS). However, the underlying mechanisms are not fully clarified. The aim of our study was to examine mRNA expression levels of cell cycle and apoptosis regulatory genes, as well as the percentage of apoptotic and S phase cells and to correlate the findings with clinical characteristics and prognosis. Sixty patients with MDS, classified according to FAB (17 RA, five RARS, 19 RAEB, nine RAEBT, ten CMML) and WHO (ten RA, three RARS, seven RCMD, two RCMD-RS, 11 RAEBI, eight RAEBII, ten CMML, and nine AML) were included in the study. We found increased expression of anti-apoptotic bclxL and mcl1 genes and decreased expression of p21 gene in MDS patients. Moreover, we found increased expression of anti-apoptotic mcl1 gene in patients with higher than Intermediate-1 IPSS group. Multivariate analysis confirmed that combined expression of apoptotic caspases 8, 3, 6, 5, 2, 7, and Granzyme B was decreased in MDS patients. Regarding cell cycle regulatory genes expression, we demonstrated increased expression of cyclin D1 in patients with CMML Increased combined expression of cyclins B, C, D1, and D2 was found in patients with cytogenetic abnormalities. The two pathways seem to be interconnected as shown by the positive correlation between CDKs 1, 2, 4, p21 and the level of apoptosis and positive correlation between apoptotic caspase 3 expression and the percentage of S phase cells. In conclusion, our study showed altered expression of genes involved in apoptosis and cell cycle in MDS and increased expression of cyclin D1 in patients with CMML.

Isolated central nervous system relapses in primary mediastinal large B‐cell lymphoma after CHOP‐like chemotherapy with or without Rituximab

Central nervous system (CNS) involvement in patients with primary mediastinal large B‐cell (PMLBCL) lymphoma is a rare event, occurring in approximately 6% of patients, on the basis of the review of the literature prior to induction of Rituximab. The aim of this retrospective study was to describe the incidence of CNS relapse among 100 consecutive patients with PMLBCL who were treated with R‐CHOPu2009±u2009RT in comparison to patients treated with CHOPu2009±u2009RT (nu2009=u200945) in 11 hospitals in Greece. Two patients experienced a CNS relapse, representing an overall frequency of 2.0% in R‐CHOP treated patients and a 2‐year actuarial incidence of 2.3%. Both patients had isolated CNS relapses. The incidence of CNS relapse after CHOP without Rituximab was 2/45 (4.4%) for a 2‐year actuarial incidence of 7.5% (pu2009=u20090.29). Again, both patients had isolated CNS relapses. Parenchymal‐only localizations accounted for 3/4 cases. Risk factors for CNS involvement could include leukocytosis, poor performance status and higher age‐adjusted International Prognostic Index, although their impact was weakened by competing risk survival analysis. Both patients relapsing after R‐CHOP required CNS radiotherapy to achieve a complete remission and be forwarded to high‐dose therapy and autologous stem cell transplantation: They are both alive and disease‐free 18 and 23u2009months after CNS relapse. Both cases relapsing after CHOP without Rituximab were salvaged by CNS radiotherapy (one also received intrathecal chemotherapy) entering long‐term remissions. In conclusion, CNS relapses are rare in PMLBCL tending to be isolated in the CNS, probably reflecting the persistence of latent CNS disease than dissemination of resistant disease. The impact of Rituximab in reducing CNS relapses remains unknown. Established risk factors for CNS involvement in aggressive lymphomas may not be helpful in assessing the risk of CNS recurrence in this disease. Routine CNS prophylaxis is not probably required in PMLBCL. Copyright

Expression analysis of proteins involved in the non homologous end joining DNA repair mechanism, in the bone marrow of adult de novo myelodysplastic syndromes

Myelodysplastic syndromes (MDS) are characterized by genetic instability which is associated with abnormal DNA repair mechanisms. The most lethal type of DNA damage are double strand DNA breaks (DSBs), which are mainly repaired by Non Homologous End Joining Mechanism (NHEJ), whose core enzyme components include the Ku70/Ku80 heterodimer, DNA–PKcs, XRCC4 and DNA Ligase IV. The aim of the present study was the analysis of expression of proteins required for NHEJ in bone marrow cells of adult de novo MDS and their association with clinical characteristics and prognosis. Our analysis included 48 cases of MDS; 19 RA, 5 RARS, 19 RAEB, 3 RAEB-T, 1 CMML, 1 transformation to AML according to FAB classification. The expression of the enzymes Ku70, Ku80, XRCC4, DNA-PKcs and Ligase IV was determined by Western Blotting. The mean Ligase IV expression value was significantly lower in MDS patients compared to normal controls (0.53 vs. 0.78, pu2009=u20090.03). A negative correlation was found between karyotype risk group and Ligase IV values. (pu2009=u20090.05). Moreover, Ku70 expression levels were significantly lower in patients with a good prognosis karyotype (pu2009=u20090.04). Furthermore, a negative correlation between Ku70 expression values and Hb levels was observed (pu2009=u20090.04). Finally, a positive correlation was observed between enzyme Ku70 expression values and level of blasts (pu2009=u20090.04). Our findings suppor-t a potential role of NHEJ enzyme Ligase IV in the pathogenesis of MDS. Larger numbers of cases need to be screened in order to draw definite conclusion.

Pure Red Cell Aplasia due to B19 Parvovirus Infection after Autologous Stem Cell Transplantation.

Parvovirus B19 is recognized as a rare cause of pure red cell aplasia (PRCA) in allogeneic stem cell (SCT) and solid organ transplant patients. We report a patient with Hodgkins disease who developed PRCA due to parvovirus B19 after autologous SCT and who had an excellent response after treatment with gamma-globulin.

CNS Involvement in AML Patient Treated with 5-Azacytidine

Central nervous system (CNS) involvement in acute myeloid leukemia (AML) is a rare complication of the disease and is associated with poor prognosis. Sometimes the clinical presentation can be unspecific and the diagnosis can be very challenging. Here we report a case of CNS infiltration in a patient suffering from AML who presented with normal complete blood count and altered mental status.