Cristina Clissa

Reduction of phosphoinositide-phospholipase C beta1 methylation predicts the responsiveness to azacitidine in high-risk MDS

Lipid signaling pathways are involved in cell growth, differentiation, and apoptosis, and could have a role in the progression of myelodysplastic syndromes (MDS) into acute myeloid leukemia (AML). Indeed, recent studies showed that phosphoinositide-phospholipase (PI-PL)Cbeta1 mono-allelic deletion correlates with a higher risk of AML evolution. Also, a single patient treated with azacitidine, a DNA methyltransferase inhibitor currently used in MDS, displayed a direct correlation between PI-PLCbeta1 gene expression and drug responsiveness. Consequently, we hypothesized that PI-PLCbeta1 could be a target for demethylating therapy. First, we analyzed the structure of PI-PLCbeta1 gene promoter, then quantified the degree of PI-PLCbeta1 promoter methylation and gene expression in MDS patients at baseline and during azacitidine administration. Indeed, PI-PLCbeta1 mRNA increased in responder patients, along with a reduction of PI-PLCbeta1 promoter methylation. Also, the molecular response correlated to and anticipated the clinical outcome, thus suggesting that PI-PLCbeta1 gene reactivation could predict azacitidine responsiveness. Our results demonstrate not only that PI-PLCbeta1 promoter is hypermethylated in high-risk MDS patients, but also that the amount of PI-PLCbeta1 mRNA could predict the clinical response to azacitidine, therefore indicating a promising new therapeutic approach.

Phosphoinositide-Phospholipase C β1 Mono-Allelic Deletion Is Associated With Myelodysplastic Syndromes Evolution Into Acute Myeloid Leukemia

PURPOSE To evaluate the association between the presence of phosphoinositide-phospholipase C beta1 (PI-PLCbeta1) mono-allelic deletion with the clinical outcome of myelodysplastic syndromes (MDS) patients. METHODS PI-PLCbeta1, PI-PLCbeta4, and PI-PLCgamma1 cytogenetic investigations were performed on 80 newly diagnosed MDS patients (18 low risk, 26 intermediate 1, 18 intermediate 2, 18 high risk) comparing the results with the clinical outcome of the patients. Moreover, fluorescent in situ hybridization results were validated by real-time polymerase chain reaction (PCR). Finally, PI-PLCbeta1 gene and protein expression were assessed by both real-time PCR and immunocytochemical experiments. RESULTS Collectively, 35 (43.75%) of 80 of the MDS patients showed a specific mono-allelic deletion of PI-PLCbeta1. Kaplan-Meier analysis revealed a significant association (P < .0001) between the PI-PLCbeta1 mono-allelic deletion and a higher risk of evolution into acute myeloid leukemia (AML), since 23 of 35 MDS patients (65.7%) bearing the PI-PLCbeta1 mono-allelic deletion evolved into AML. Even in multivariate analysis, the PI-PLCbeta1 mono-allelic deletion retained a higher significance, with a P < .001, as a prognostic factor of evolution into AML (odds ratio [OR] 1.83; 95% CI, 2.26 to 17.24; P = .00045). Finally, PI-PLCbeta1 deletion was related to an altered gene and protein expression. CONCLUSION PI-PLCbeta1 mono-allelic deletion is associated with a worse clinical outcome in MDS patients, hinting at the identification of a new group at higher risk of AML evolution and representing a reliable prognostic tool. Moreover, targeting PI-PLCbeta1 pathways might emerge as a new therapeutic strategy for MDS.

Computed Tomographic Pulmonary Angiography for Diagnosis of Invasive Mold Diseases in Patients With Hematological Malignancies

BACKGROUND Invasive mold diseases (IMDs) of the lung remain a challenge for immunocompromised patients. Although timely diagnosis and treatment are crucial for the outcome of the infection, the poor sensitivity of microbiological techniques and the limited specificity of chest high-resolution computed tomography (HRCT) often delay definitive diagnosis of these infections. METHODS To explore the diagnostic utility of computed tomographic pulmonary angiography (CTPA) for detecting angioinvasive patterns of pulmonary infection, we performed a single-center, prospective, nonrandomized trial involving 36 patients with hematological malignancies who had clinical suspicion of IMD, as defined by European Organization for Research and Treatment of Cancer/Mycosis Study Group diagnostic criteria. RESULTS We found that 5 of 5 patients with proven IMD had CTPA-positive findings consistent with interruption of the arterial vessels (concordance, 100%). CTPA findings were positive in 5 of 7 patients with probable IMD (findings for 2 were considered false negative because lesions were too small or not evaluable). In 15 of 24 patients with a final diagnosis of possible IMD, CTPA findings were negative for 14 patients and were positive for 1 patient, who had septic emboli associated with Staphylococcus aureus bacteremia. CTPA findings were positive in the remaining 9 patients with a final diagnosis of possible IMD at the end of the study. CONCLUSIONS We conclude that CTPA appears to be a promising tool to exclude the diagnosis of IMD in high-risk patients without specific findings on HRCT scans, and it is most useful in the presence of well-circumscribed lesions in which there is suspicion for IMD.

Prospective Phase II Study on 5-Days Azacitidine for Treatment of Symptomatic and/or Erythropoietin Unresponsive Patients with Low/INT-1–Risk Myelodysplastic Syndromes

Purpose: This phase II prospective study aimed to evaluate the efficacy and safety of 5-days azacytidine (5d-AZA) in patients with low-risk myelodysplastic syndromes (MDS). Second, single-nucleotide polymorphism (SNP) genetic profile and phosphoinositide-phospholipase C (PI-PLC) β1 levels were studied to evaluate possible biologic markers able to predict the hematologic response. Experimental Design: The study tested a lower intensity schedule of azacytidine. The treatment plan consisted of 75 mg/sqm/d subcutaneous administered for 5 days every 28 days, for a total of 8 cycles. Results: Thirty-two patients were enrolled in the study. The overall response rate was 47% (15 of 32) on intention-to-treat and 58% (15 of 26) for patients completing the treatment program. In this latter group, 5 (19%) achieved complete remission (CR) and 10 (38%) had hematologic improvement, according to the International Working Group (IWG) criteria. Three patients have maintained their hematologic improvement after 37, 34, and 33 months without other treatments. Moreover, 21 and 2 of 26 cases completing 8 cycles were transfusion-dependent for red blood cells and platelets at baseline, respectively. Of these, 7 (33%) and 2 (100%) became transfusion-independent at the end of the treatment program, respectively. Grade 3–4 neutropenia occurred in 28% of patients and 4 patients died early due to infections or hemorrhage. SNP results were not significantly correlated to the clinical outcome, whereas PI-PLCβ1 level anticipated either positive or negative clinical responses. Conclusions: 5d-AZA is safe and effective in a proportion of patients with low-risk MDS. PI-PLCβ1 gene expression is a reliable and dynamic marker of response that can be useful to optimize azacytidine therapy. Clin Cancer Res; 19(12); 3297–308. ©2013 AACR.

Synergistic induction of PI-PLCβ1 signaling by azacitidine and valproic acid in high-risk myelodysplastic syndromes

The association between azacitidine (AZA) and valproic acid (VPA) has shown high response rates in high-risk myelodysplastic syndromes (MDS) cases with unfavorable prognosis. However, little is known about the molecular mechanisms underlying this therapy, and molecular markers useful to monitor the disease and the effect of the treatment are needed. Phosphoinositide-phospholipase C (PI-PLC) β1 is involved in both genetic and epigenetic mechanisms of MDS progression to acute myeloid leukemia. Indeed, AZA as a single agent was able to induce PI-PLCβ1 expression, therefore providing a promising new tool in the evaluation of response to demethylating therapies. In this study, we assessed the efficacy of the combination of AZA and VPA on inducing PI-PLCβ1 expression in high-risk MDS patients. Furthermore, we observed an increase in Cyclin D3 expression, a downstream target of PI-PLCβ1 signaling, therefore suggesting a potential combined activity of AZA and VPA in high-risk MDS in activating PI-PLCβ1 signaling, thus affecting cell proliferation and differentiation. Taken together, our findings might open up new lines of investigations aiming at evaluating the role of the activation of PI-PLCβ1 signaling in the epigenetic therapy, which may also lead to the identification of innovative targets for the epigenetic therapy of high-risk MDS.

Epigenetic regulation of nuclear PI-PLCbeta1 signaling pathway in low-risk MDS patients during azacitidine treatment

Phosphoinositide-phospholipase C (PI-PLC) beta1 can be considered a specific target for demethylating therapy in high-risk myelodysplastic syndrome (MDS) patients, as azacitidine treatment has been associated with a PI-PLCbeta1-specific promoter demethylation, and induction of PI-PLCbeta1 gene and protein expression. However, little is known about the molecular effect of azacitidine in low-risk MDS or the functional mechanisms linked with azacitidine effect on PI-PLCbeta1 promoter. In the present study, we further investigated the role of epigenetic regulation of PI-PLCbeta1, mainly focusing on the structure of the PI-PLCbeta1 promoter. We first examined the effect of azacitidine on PI-PLCbeta1 promoter methylation and gene expression in low-risk MDS. Moreover, we studied the expression of key molecules associated with the nuclear inositide signaling pathways, such as cyclin D3. By applying a chromatin immunoprecipitation method, we also studied the correlation between the demethylating effect of azacitidine and the degree of recruitment to PI-PLCbeta1 promoter of some transcription factors implicated in hematopoietic stem cell proliferation and differentiation, as well as of the methyl-CpG-binding domain proteins, which specifically interact with methylated DNA. Taken together, our results hint at a specific involvement of PI-PLCbeta1 in epigenetic mechanisms, and are particularly consistent with the hypothesis of a role for PI-PLCbeta1 in azacitidine-induced myeloid differentiation.

Nuclear inositide signaling in myelodysplastic syndromes

Myelodysplastic syndromes (MDS) are defined as clonal hematopoietic stem‐cell disorders characterized by ineffective hematopoiesis in one or more of the lineages of the bone marrow. Although distinct morphologic subgroups exist, the natural history of MDS is progression to acute myeloid leukemia (AML). However, the molecular the mechanisms the underlying MDS evolution to AML are not completely understood. Inositides are key cellular second messengers with well‐established roles in signal transduction pathways, and nuclear metabolism elicited by phosphoinositide‐specific phospholipase C (PI‐PLC) β1 and Akt plays an important role in the control of the balance between cell cycle progression and apoptosis in both normal and pathologic conditions. Recent findings evidenced the role played by nuclear lipid signaling pathways, which could become promising therapeutic targets in MDS. This review will provide a concise and updated revision of the state of art on this topic. J. Cell. Biochem. 109: 1065–1071, 2010.

PKR is activated in MDS patients and its subcellular localization depends on disease severity.

PKR is activated in MDS patients and its subcellular localization depends on disease severity

Activation of nuclear inositide signalling pathways during erythropoietin therapy in low-risk MDS patients

Inositide signaling pathways can have a role in the Myelodysplastic Syndromes (MDS) progression to acute myeloid leukemia. Erythropoietin (EPO) is currently used in low-risk MDS, where it successfully corrects anemia in 50–70% of patients. However, some MDS patients are refractory to this treatment and little is known about the exact molecular mechanisms underlying the effect of EPO in these subjects. Here, we investigated the role of inositide pathways in low-risk MDS treated with EPO, mainly focusing on the Akt/PI-PLC (Phosphoinositide-Phospholipase C) gamma1 axis, which is activated by the EPO receptor, and PI-PLCbeta1/Cyclin D3 signaling, as Cyclin D3 is associated with hematopoietic proliferation and differentiation. Interestingly, EPO responder patients showed a specific activation of both the Akt/PI-PLCgamma1 pathway and beta-Globin gene expression, while nonresponders displayed an increase in PI-PLCbeta1 signaling. Moreover, in normal CD34+ cells induced to erythroid differentiation, PI-PLCbeta1 overexpression abrogated both EPO-induced Akt phosphorylation and beta-Globin expression. Overall, these findings suggest that PI-PLCbeta1 can act as a negative regulator of erythroid differentiation and confirm the involvement of Akt/PI-PLCgamma1 pathway in EPO signaling, therefore contributing to the comprehension of the effect of EPO in low-risk MDS and possibly paving the way to the identification of MDS patients at higher risk of refractoriness to EPO treatment.

The role of the immunosuppressive microenvironment in acute myeloid leukemia development and treatment

Functional interplay between acute myeloid leukemia (AML) cells and the bone marrow microenvironment is a distinctive characteristic of this hematological cancer. Indeed, a large body of evidence suggests that proliferation, survival and drug resistance of AML are sustained and modulated by the bone marrow immunosuppressive microenvironment, where both innate and adaptive immune responses are profoundly deregulated. Furthermore, the presence of a number of different immunosuppressive mechanisms results in massive immune deregulation, which causes the eventual escape from natural immune control. Modulating the immune system, as documented by 40 years of stem cell transplantation, may improve survival of AML patients, as the immune system is clearly able to recognize and attack leukemic cells. The understanding of the factors responsible for the escape from immune destruction in AML, which becomes more prominent with disease progression, is necessary for the development of innovative immunotherapeutic treatment modalities in AML.