Alexandra Papoudou-Bai

Bio: Alexandra Papoudou-Bai is an academic researcher from University of Ioannina. The author has contributed to research in topics: Medicine & Lymphoma. The author has an hindex of 16, co-authored 74 publications receiving 777 citations. Previous affiliations of Alexandra Papoudou-Bai include RMIT University.

Promoter methylation of argininosuccinate synthetase-1 sensitises lymphomas to arginine deiminase treatment, autophagy and caspase-dependent apoptosis

Abstract: Tumours lacking argininosuccinate synthetase-1 (ASS1) are auxotrophic for arginine and sensitive to amino-acid deprivation. Here, we investigated the role of ASS1 as a biomarker of response to the arginine-lowering agent, pegylated arginine deiminase (ADI-PEG20), in lymphoid malignancies. Although ASS1 protein was largely undetectable in normal and malignant lymphoid tissues, frequent hypermethylation of the ASS1 promoter was observed specifically in the latter. A good correlation was observed between ASS1 methylation, low ASS1 mRNA, absence of ASS1 protein expression and sensitivity to ADI-PEG20 in malignant lymphoid cell lines. We confirmed that the demethylating agent 5-Aza-dC reactivated ASS1 expression and rescued lymphoma cell lines from ADI-PEG20 cytotoxicity. ASS1-methylated cell lines exhibited autophagy and caspase-dependent apoptosis following treatment with ADI-PEG20. In addition, the autophagy inhibitor chloroquine triggered an accumulation of light chain 3-II protein and potentiated the apoptotic effect of ADI-PEG20 in malignant lymphoid cells and patient-derived tumour cells. Finally, a patient with an ASS1-methylated cutaneous T-cell lymphoma responded to compassionate-use ADI-PEG20. In summary, ASS1 promoter methylation contributes to arginine auxotrophy and represents a novel biomarker for evaluating the efficacy of arginine deprivation in patients with lymphoma.

The prolyl-hydroxylase EGLN3 and not EGLN1 is inactivated by methylation in plasma cell neoplasia.

Abstract: EGLN1 and EGLN3 are members of the egg-laying-defective 9 (EglN) prolyl-hydroxylases which during normoxia catalyse hydroxylation of the hypoxia-inducible factor (HIF)-1alpha, thereby promoting its ubiquitination by a complex containing the von Hippel-Lindau (VHL) tumour suppressor. EGLN3 also has pro-apoptotic activity in some cell types. Analyses of a well-characterised series of cases of plasma cell dyscrasias, including multiple myeloma (MM), Waldenstrom's macroglobulinaemia (WM) and monoclonal gammopathy of undetermined significance (MGUS) surprisingly demonstrated that the CpG island of EGLN3, and not EGLN1, is frequently methylated in these disorders. Multiple myeloma patients with a methylated EGLN3 promoter showed trends towards an increased risk of death, bone lytic lesions, anaemia, advanced stage of disease and the presence of extramedullary disease. Those individuals with methylation in the EGLN3 CpG island also had significantly lower albumin levels. These data suggest that the prolyl-hydroxylases may be a novel class of potential tumour suppressors in plasma cell neoplasia that warrant further investigation with regard to their potential utility as biomarkers. Moreover, we observed that EGLN3 is also methylated at high frequency in B-cell lymphoma subtypes, implying that loss of EGLN3 is an important epigenetic event not only in plasma cell neoplasias but also in B-cell neoplasias.

Primary lymphomas of bone.

Abstract: Primary lymphomas of bone are uncommon malignancies. The vast majority of them are non-Hodgkin lymphoma (NHL), whereas primary Hodgkin lymphoma (HL) of bone is extremely rare. Patients with primary NHL of bone commonly present with local bone pain, soft tissue swelling, and a mass or a pathological fracture. There is a slight male preponderance, and most patients are over 45-50 years of age. Primary NHL of bone can arise in any part of the skeleton, but long bones (femurs, tibia) are the most common sites of presentation. Comprehensive immunohistochemical studies are required to establish an accurate histological diagnosis of primary NHL of bone. Most cases of primary NHL of bone are classified as diffuse large B-cell lymphomas (DLBCL) in the World Health Organisation (WHO) classification of hematological malignancies. On full staging evaluation, most patients have disease of stage IE or IIE according to the Ann Arbor system. Several studies indicate that patients with primary NHL of bone have a favorable outcome, especially when treated by combined modality therapy. A number of studies reported that clinical stage is the most important prognostic variable in predicting overall survival. Interestingly, the rare occurrence of primary lymphoma of bone is in contrast with the frequency of plasma cell tumors in bone. This could be due to the fact that, during normal B-cell differentiation, the bone marrow is the normal site of homing of plasma cells which are terminally-differentiated, immunoglobulin-secreting post-germinal center B-cells. In this respect, there is circumstancial evidence that primary NHL of bone may represent tumors of post-germinal center B-cells. The present review summarizes data on the histogenesis of primary NHL of bone in view of the recent histogenetic classification of DLBCL on the basis of the B-cell differentiation gene expression profiles (germinal center vs. post-germinal center B-cell differentiation).

Expression patterns of the activator protein-1 (AP-1) family members in lymphoid neoplasms.

Abstract: The activator protein-1 (AP-1) is a dimeric transcription factor composed of proteins belonging to the Jun (c-Jun, JunB and JunD), Fos (c-Fos, FosB, Fra1 and Fra2) and activating transcription factor protein families. AP-1 is involved in various cellular events including differentiation, proliferation, survival and apoptosis. Deregulated expression of AP-1 transcription factors is implicated in the pathogenesis of various lymphomas such as classical Hodgkin lymphomas, anaplastic large cell lymphomas, diffuse large B cell lymphomas and adult T cell leukemia/lymphoma. The main purpose of this review is the analysis of the expression patterns of AP-1 transcription factors in order to gain insight into the histophysiology of lymphoid tissues and the pathology of lymphoid malignancies.

Novel mechanisms of glucocorticoid resistance in childhood acute lymphoblastic leukemia.

Abstract: 2458 Despite dramatic improvements in treatment over the past 40 years, acute lymphoblastic leukemia (ALL) remains one of the most common causes of death from disease in childhood. Glucocorticoids are among the most effective agents used in the treatment of lymphoid malignancies, and patient response to treatment is an important determinant of long-term outcome in childhood ALL. In spite of its clinical significance, the molecular basis of glucocorticoid resistance is still poorly understood. The aim of this study was to develop an experimental model system to define clinically relevant mechanisms of glucocorticoid resistance in childhood ALL. An in vivo model of childhood ALL has been developed in our laboratory, using patient biopsies established as xenografts in immune-deficient nonobese diabetic severe-combined immunodeficient (NOD/SCID) mice. This model is highly representative of the human disease (Lock et al., Blood, 99: 4100-4108, 2002). The in vivo responses of these xenografts to the glucocorticoid dexamethasone (DEX) correlated significantly with patient outcome (p 1 μM) in xenografts from six patients, five of whom died of their disease. In contrast, four DEX-sensitive xenografts (IC50 values 2-fold in sensitive xenografts within 8 hours of treatment. In contrast, Bim induction was dramatically attenuated in DEX-resistant xenografts. These results have identified a clinically significant and novel mechanism of glucocorticoid resistance in childhood ALL, which occurs downstream of receptor-ligand interactions, but upstream of the signalling pathway resulting in Bim induction and apoptosis.

Prognostic Value of Tumor-Infiltrating Lymphocytes in Triple-Negative Breast Cancers From Two Phase III Randomized Adjuvant Breast Cancer Trials: ECOG 2197 and ECOG 1199

Abstract: Purpose Recent studies suggest that tumor-infiltrating lymphocytes (TILs) are associated with disease-free (DFS) and overall survival (OS) in operable triple-negative breast cancer (TNBC). We seek to validate the prognostic impact of TILs in primary TNBCs in two adjuvant phase III trials conducted by the Eastern Cooperative Oncology Group (ECOG). Patients and methods Full-face hematoxylin and eosin–stained sections of 506 tumors from ECOG trials E2197 and E1199 were evaluated for density of TILs in intraepithelial (iTILs) and stromal compartments (sTILs). Patient cases of TNBC from E2197 and E1199 were randomly selected based on availability of sections. For the primary end point of DFS, association with TIL scores was determined by fitting proportional hazards models stratified on study. Secondary end points were OS and distant recurrence–free interval (DRFI). Reporting recommendations for tumor marker prognostic studies criteria were followed, and all analyses were prespecified. Results The majority of 481 evaluable cancers had TILs (sTILs, 80%; iTILs, 15%). With a median follow-up of 10.6 years, higher sTIL scores were associated with better prognosis; for every 10% increase in sTILs, a 14% reduction of risk of recurrence or death (P = .02), 18% reduction of risk of distant recurrence (P = .04), and 19% reduction of risk of death (P = .01) were observed. Multivariable analysis confirmed sTILs to be an independent prognostic marker of DFS, DRFI, and OS. Conclusion In two national randomized clinical trials using contemporary adjuvant chemotherapy, we confirm that stromal lymphocytic infiltration constitutes a robust prognostic factor in TNBCs. Studies assessing outcomes and therapeutic efficacies should consider stratification for this parameter.

Reconstructing and Reprogramming the Tumor-Propagating Potential of Glioblastoma Stem-like Cells

Abstract: Developmental fate decisions are dictated by master transcription factors (TFs) that interact with cis-regulatory elements to direct transcriptional programs. Certain malignant tumors may also depend on cellular hierarchies reminiscent of normal development but superimposed on underlying genetic aberrations. In glioblastoma (GBM), a subset of stem-like tumor-propagating cells (TPCs) appears to drive tumor progression and underlie therapeutic resistance yet remain poorly understood. Here, we identify a core set of neurodevelopmental TFs (POU3F2, SOX2, SALL2, and OLIG2) essential for GBM propagation. These TFs coordinately bind and activate TPC-specific regulatory elements and are sufficient to fully reprogram differentiated GBM cells to "induced" TPCs, recapitulating the epigenetic landscape and phenotype of native TPCs. We reconstruct a network model that highlights critical interactions and identifies candidate therapeutic targets for eliminating TPCs. Our study establishes the epigenetic basis of a developmental hierarchy in GBM, provides detailed insight into underlying gene regulatory programs, and suggests attendant therapeutic strategies. PAPERCLIP: