Sotirios G. Papageorgiou

The role of microRNAs in normal and malignant hematopoiesis

MicroRNAs are small non‐coding RNAs that act at the post‐transcriptional level, regulating protein expression by repressing translation or destabilizing mRNA target. Because of their discovery, microRNAs have been associated with almost every normal cell function, including proliferation, differentiation and apoptosis. Several lines of evidence suggest that they have an important role in normal hematopoiesis as exemplified by the role of mir‐155 and mir‐150 in the differentiation of B and T lymphocytes, the suppressive role of mir‐221 and mir‐222 in erythroid differentiation, the inhibitory effect of mir‐181 on hematopoietic differentiation and the induction of myeloid differentiation by mir‐223. Moreover, they play a role both as oncogenes, probably by a variety of mechanisms, namely through elimination of tumor suppressor proteins, or as tumor suppressor genes by targeting oncogenic mRNAs. Their aberrant expression has been associated with solid tumors and hematopoietic malignancies as suggested by the frequent deletion of mir‐15a and mir‐16‐1 in chronic lymphocytic leukemia, the increased levels of mir‐155 in diffuse large B‐cell lymphomas and the increased levels of mir‐181 in acute myeloid leukemia M1 and M2. The purpose of this review is to summarize current knowledge on the role of microRNAs in normal hematopoiesis and hematopoietic malignancies and, moreover, to highlight their role as potential therapeutic tools.

Rituximab, Cyclophosphamide, Doxorubicin, Vincristine, and Prednisone with or Without Radiotherapy in Primary Mediastinal Large B-Cell Lymphoma: The Emerging Standard of Care

UNLABELLED More aggressive treatment approaches (methotrexate, cytarabine, cyclophosphamide, vincristine, prednisone, and bleomycin [the MACOP-B regimen] or consolidation with high-dose therapy and autologous stem cell transplantation) have been considered to be superior to cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) in patients with primary mediastinal large B-cell lymphoma (PMLBCL). Rituximab-CHOP (R-CHOP) is the standard of care for diffuse large B-cell lymphoma, whereas efficacy in PMLBCL has not been adequately confirmed. PATIENT AND METHODS Seventy-six consecutive PMLBCL patients who received R-CHOP with or without radiotherapy (RT) were compared with 45 consecutive historical controls treated with CHOP with or without RT. Baseline characteristics of the two groups were balanced. RESULTS The rate of early treatment failure was much lower with R-CHOP with or without RT (9% versus 30%; p = .004). The 5-year freedom from progression rate after R-CHOP with or without RT was 81%, versus 48% for CHOP with or without RT (p < .0001). The 5-year event-free survival rates were 80% and 47% (p < .0001) and the 5-year overall and lymphoma-specific survival rates were 89% and 69% (p = .003) and 91% and 69% (p = .001), respectively, with only seven of 76 lymphoma-related deaths. Among R-CHOP responders, 52 of 68 received RT. CONCLUSIONS Based on these results, most patients with PMLBCL appear to be cured by R-CHOP in 21-day cycles with or without RT, which could be the current standard of care. Therefore, the need for more aggressive treatment strategies is questionable unless high-risk patients are adequately defined. Further studies are required to establish the precise role of RT.

Extracorporeal photopheresis in combination with bexarotene in the treatment of mycosis fungoides and Sézary syndrome

were histologically compatible with MDE. Elastica staining showed band-like and sharply demarcated elastolysis in the upper reticular dermis with conservation of the fine vertically orientated elastic fibres of the papillary dermis. In addition, focal areas of fragmented and absent elastic fibres were observed in the mid-reticular dermis (Fig. 2c). Only a scant perivascular lymphohistiocytic infiltrate was seen in the upper dermis. On closer examination, isolated and small clusters of CD68 (PGM1)-positive multinucleated giant cells were detected in the mid-reticular dermis showing elastophagocytosis. This case documents the transition of AEGCG into a noninflammatory end stage, clinically and histologically compatible with MDE. The pathogenesis of MDE is still unknown. Exposure to natural or artificial UV radiation frequently precedes the onset of MDE suggesting a pathogenic UV-mediated immunological mechanism. However, MDE lesions are not usually confined to sun-exposed areas, so that other cofactors are likely to play a role. Extensive sun exposure was denied by our patient. An association of MDE with nicotine abuse and oral contraceptives as in our case has repeatedly been reported. It is still unclear if this is mere coincidence or if these substances represent relevant trigger factors. MDE has been described after resolution of urticaria, erythematous skin changes and lesions resembling granuloma annulare. In the majority of cases, however, MDE develops without a clinically obvious inflammatory prodromal stage. The clinical course in our patient suggests that AEGCG and MDE might represent different stages in the clinical spectrum of dermal elastolysis. After the inflammatory prodromal stage of AEGCG and phagocytosis of elastic fibres by multinucleate giant cells the noninflammatory ‘burned-out’ end stage of MDE could result in a loss of elastic fibres in the mid-dermis. As elastophagocytosis by macrophages is, to a much lesser extent, also a feature of early inflammatory MDE lesions, AEGCG might represent a severe inflammatory variant of the same entity.

Antiphospholipid syndrome: a predisposing factor for early onset HELLP syndrome

Hemolysis elevated liver enzymes low platelets syndrome (HELLP) is a relatively rare pregnancy-related thrombotic microangiopathic disorder, usually observed during the third trimester. Its incidence seems to be increased in patients with antiphospholipid syndrome (APS). In this report, we describe a 33-year-old pregnant woman with previously known primary APS who developed early onset HELLP syndrome during the 15th week of gestation. We also review the literature about this interesting relationship between APS and HELLP.

The Novel Member of the BCL2 Gene Family, BCL2L12, Is Substantially Elevated in Chronic Lymphocytic Leukemia Patients, Supporting Its Value As a Significant Biomarker

BCL2L12 is a recently identified gene belonging to the BCL2 family, members of which are implicated in hematologic malignancies, including chronic lymphocytic leukemia (CLL). The aim of this study was to analyze the mRNA expression of the novel apoptosis-related gene BCL2L12 in patients with CLL and to examine its prognostic and predictive value and potential clinical application as a novel molecular biomarker for CLL. For this purpose, total RNA was isolated from peripheral blood of 65 CLL patients and 23 healthy donors. An ultrasensitive quantitative real-time polymerase chain reaction methodology for BCL2L12 and BCL2 mRNA quantification was developed using SYBR Green chemistry. After preparing cDNA by reverse transcription, relative quantification analysis was performed using the comparative C(T) (2(-ΔΔCT)) method. Furthermore, analysis of IGHV mutational status, CD38 expression, and detection of early apoptosis by double staining with Annexin V-FITC and propidium iodide were performed. According to our findings, BCL2L12 mRNA expression is significantly higher in CLL patients than in healthy donors. Receiver operating characteristic analysis demonstrated that BCL2L12 expression had significant discriminatory value, distinguishing very efficiently CLL patients from the non-leukemic population. Moreover, BCL2L12 expression predicts the presence of CLL, as demonstrated by both univariate and multivariate logistic regression analyses. Finally, high BCL2L12 mRNA levels are associated with advanced clinical stage and predict shorter overall survival in CLL patients.

Hypoxia-inducible factors in mantle cell lymphoma: implication for an activated mTORC1→HIF-1α pathway

Aberrant activation of phosphoinositide-3 kinase/Akt (PI3K/Akt) and mammalian target of rapamycin (mTOR) signaling is implicated in the pathogenesis of mantle cell lymphoma (MCL). We previously showed oncogenic activation of PI3K/Akt pathway in a subset of MCL patients. In this study, we investigated downstream the immunohistochemical expression of Ser2448pmTOR [indicative of mTOR complex 1 (mTORC1) activation status] as well as of hypoxia-inducible factor 1 alpha (HIF-1α), hypoxia-inducible factor 2 alpha (HIF-2α), p53, and p21 in the same series of MCL patients. Additionally, correlation of these proteins with activated Akt (Ser473pAkt) and established histological prognostic factors was examined. Thirty-five tissue samples (28 classical type and seven blastoid variant) were included. The neoplastic cells expressed Ser2448pmTOR in 61.7%, HIF-1α in 73.5%, HIF-2α in 23.5%, and p53 in 18.2% of patients, while p21 was negative in all examined samples. In addition, 72% of patients who expressed HIF-1α had also Ser2448pmTOR expression (p = 0.041). HIF-1α expression was also correlated to an elevated (≥30%) Ki-67 (p = 0.031) and blastoid variant of disease (p = 0.017). In conclusion, we report for the first time common expression of HIF-alphas, especially HIF-1α, in MCL patients. Furthermore, an overall activation of mTORC1→HIF-1α axis and a potential role of Ser2448pmTOR in the regulation of HIF-1α in MCL patients are suggested. Finally, HIF-1α appears to be associated with more aggressive disease. A pathogenetic role for both mTORC1 and HIF-1α in MCL is implied, which will possibly lead to more efficient target therapies.

Mutational and methylation analysis of the cyclin-dependent kinase 4 inhibitor (p16INK4A) gene in chronic lymphocytic leukemia.

Abstract:  Objectives: Chronic lymphocytic leukemia (CLL) comprises a heterogenous group of at least two types of disease entities characterized by distinctive clinical, immunophenotypical and genetic features. The molecular mechanisms underlying the pathogenesis and the histological transformation of CLL are not well known. The INK4A/p16, a cyclin dependent kinase inhibitor has been considered as a tumor suppressor gene. Inactivation of this gene by homozygous deletions, mutations and hypermethylation occurs in a variety of human neoplasms. The aim of the present study was to determine the frequency of p16 gene deletions and mutations as well as the methylation status of the same gene in CLL patients. Methods: We examined 34 samples from CLL patients by Southern Blotting, Single‐Strand Conformation Polymorphism (SSCP), DNA sequencing and Methylation‐Specific PCR. Results: Southern Blot analysis revealed non‐rearranged bands in 33/34 cases. Homozygous deletions were not observed in any case. In 1/34 case a rearranged band was detected with EcoRI enzyme. The PCR‐SSCP analysis of exons 1 and 3 revealed normal pattern of migration in all cases examined. The analysis of exon 2 revealed abnormal migration pattern in 2/34 cases (5.8%). Sequencing of these cases revealed the presence of the ALA148THR polymorphism. Methylation analysis of p16 gene promoter revealed hypermethylation of CpG islands in 6/34 cases (17.6%). Conclusion: These results indicate that genetic alterations of p16 gene are rare events in patients with CLL. The clarification of the role of p16 gene promoter methylation in the pathogenesis and evolution of CLL needs further investigation.

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‐CHOP ± RT in comparison to patients treated with CHOP ± RT (n = 45) 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% (p = 0.29). 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 23 months 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

Extracorporeal photopheresis in refractory chronic graft-versus-host disease: The influence on peripheral blood T cell subpopulations. A study by the Hellenic Association of Hematology

Extracorporeal photopheresis (ECP) has been established as an effective treatment modality for patients with chronic extensive graft-versus host disease (GVHD). In the present study, we evaluated the influence of ECP on the numbers of CD4+, CD8+, CD20+, CD56+ cells, and on T-regulatory (Tregs), as well as on the numbers of naïve, central memory (CM), and effector memory (EM) T-cells in patients treated for refractory chronic GVHD. Flow cytometric analysis of peripheral blood lymphocytes was performed for the calculation of the different T-cell subsets. Patients with GVHD had a higher percentage of EM-CD4+ cells in comparison with healthy donors (p=0.046). The percentages of naïve-CD8+, naïve-CD4+, CM-CD8+, CM-CD4+, EM-CD8+, and Tregs were not different between patients with GVHD and healthy donors. Similarly there was no statistical difference in the percentages of naïve, CM, and EM CD4+ and CD8+ cells before and after 3 months of treatment with ECP. However, in the subset of Tregs a statistically significant increase was observed after 3 months of treatment with ECP (p=0.015). Responders to ECP had statistically significantly higher absolute numbers of CD4+, and CD8+ cells, in comparison with non-responders. These data further support the concept that ECP does not cause immune-suppression, but should be better considered as an immune-modulating treatment.

Extracorporeal photopheresis in the treatment of chronic graft-versus-host disease. The Hellenic experience: a study by the Hellenic association of hematology.

The Hellenic experience regarding the efficacy of extracorporeal photopheresis (ECP) in the treatment of 58 patients with chronic graft-versus-host disease (cGVHD) is presented in this article. All 58, except one patient, had failed at least one line of immunosuppressive treatment including steroids. Thirty-three out of 58 patients showed an objective overall response to ECP in a median time of 10 weeks after the onset of treatment. The cumulative incidence of overall response was 65.1%. In multivariate analysis, the presence of severe chronic GVHD was the only parameter associated with a significantly lower probability of response to treatment (RR=0.4, CI 95% 0.2-0.9, p=0.03). Responders to treatment with ECP were more likely to discontinue immunosuppression, had a lower probability of non-relapse mortality (RR=0.2, CI 95% 0.1-0.5, p=0.002), and a higher probability of overall survival (RR=7.8, CI 95% 3-20, p<0.001) in comparison with non-responders. Eight out of 58 patients experienced relapse of the original disease. The cumulative incidence of relapse in the group of responders to ECP was 6%, while it was 25% in the group of non-responders to ECP. In multivariate analysis, response to treatment with ECP was the only parameter statistically associated with a significantly decreased hazard of relapse (RR=0.1, CI 95% 0.1-0.7, p=0.02). ECP should be tested as first-line treatment in patients with cGVHD with the aim to minimize the duration of immunosuppression and the rate of relapse of the malignant disease.