Deregulation of Aiolos expression in chronic lymphocytic leukemia is associated with epigenetic modifications.

Chronic lymphocytic leukemia (CLL) is characterized by a clonal accumulation of mature neoplastic B cells that are resistant to apoptosis. Aiolos, a member of the Ikaros family of zinc-finger transcription factors, plays an important role in the control of mature B lymphocyte differentiation and maturation. In this study, we showed that Aiolos expression is up-regulated in B-CLL cells. This overexpression does not implicate isoform imbalance or disturb Aiolos subcellular localization. The chromatin status at the Aiolos promoter in CLL is defined by the demethylation of DNA and an enrichment of euchromatin associated histone markers, such as the dimethylation of the lysine 4 on histone H3. These epigenetic modifications should allow its upstream effectors, such as nuclear factor-κB, constitutively activated in CLL, to gain access to promoter, resulting up-regulation of Aiolos. To determine the consequences of Aiolos deregulation in CLL, we analyzed the effects of Aiolos overexpression or down-regulation on apoptosis. Aiolos is involved in cell survival by regulating the expression of some Bcl-2 family members. Our results strongly suggest that Aiolos deregulation by epigenetic modifications may be a hallmark of CLL.

Atorvastatin prevents Plasmodium falciparum cytoadherence and endothelial damage.

BACKGROUND: The adhesion of Plasmodium falciparum parasitized red blood cell (PRBC) to human endothelial cells (EC) induces inflammatory processes, coagulation cascades, oxidative stress and apoptosis. These pathological processes are suspected to be responsible for the blood-brain-barrier and other organs' endothelial dysfunctions observed in fatal cases of malaria. Atorvastatin, a drug that belongs to the lowering cholesterol molecule family of statins, has been shown to ameliorate endothelial functions and is widely used in patients with cardiovascular disorders. METHODS: The effect of this compound on PRBC induced endothelial impairments was assessed using endothelial co-culture models. RESULTS: Atorvastatin pre-treatment of EC was found to reduce the expression of adhesion molecules and P. falciparum cytoadherence, to protect cells against PRBC-induced apoptosis and to enhance endothelial monolayer integrity during co-incubation with parasites. CONCLUSIONS: These results might suggest a potential interest use of atorvastatin as a protective treatment to interfere with the pathophysiological cascades leading to severe malaria.

Differential epigenetic regulation of Aiolos expression in human tumoral cell lines and primary cells.

In order to investigate the epigenetic component of Aiolos regulation, we analyzed the methylation status of its 5' CpG island in relation to histone modifications. Inhibition of CpG methylation restores Aiolos expression, as well as euchromatin-associated markers, in U937 and 1106 mel cell lines. DNA methylation and low levels of euchromatin-associated signatures are observed in U937 and 1106 mel cell lines, while the opposite characterizes Daudi, Jurkat, T and B cells. CpG methylation is not necessary to repress transcription in monocytes and melanocytes where silencing mechanism involves heterochromatin-associated signature. We show that DNA methylation directs Aiolos silencing and chromatin status in tumor cell lines, while in primary cells is mainly regulated by histone modifications.

Cell penetrating peptides as a therapeutic strategy in chronic lymphocytic leukemia.

PP2A is a serine/threonine phosphatase critical to a number of physiological and developmental processes. In this manuscript, we show that a peptide, specifically blocking the caspase- 9/PP2A interaction, DPT-C9h, induces apoptosis in primary tumour B cells isolated from peripheral blood mononuclear cells or bone marrow of chronic lymphocytic leukemia (CLL) patients, but not on B cells obtained from healthy donors (HD). Moreover, in both CLL patients and HD, DPT-C9h does not induce apoptosis on T- and NKcells and monocytes. Our results strongly suggest that DPT-C9h peptide has tumour specificity and that caspase-9/PP2Ac interaction constitutes a novel therapeutic approach for the treatment in CLL patients.

Specific targeting of caspase-9/PP2A interaction as potential new anti-cancer therapy.

PURPOSE: PP2A is a serine/threonine phosphatase critical to physiological processes, including apoptosis. Cell penetrating peptides are molecules that can translocate into cells without causing membrane damage. Our goal was to develop cell-penetrating fusion peptides specifically designed to disrupt the caspase-9/PP2A interaction and evaluate their therapeutic potential in vitro and in vivo. EXPERIMENTAL DESIGN: We generated a peptide containing a penetrating sequence associated to the interaction motif between human caspase-9 and PP2A (DPT-C9h), in order to target their association. Using tumour cell lines, primary human cells and primary human breast cancer (BC) xenografts, we investigated the capacity of DPT-C9h to provoke apoptosis in vitro and inhibition of tumour growth (TGI) in vivo. DPT-C9h was intraperitoneally administered at doses from 1 to 25 mg/kg/day for 5 weeks. Relative Tumour Volume (RTV) was calculated. RESULTS: We demonstrated that DPT-C9h specifically target caspase-9/PP2A interaction in vitro and in vivo and induced caspase-9-dependent apoptosis in cancer cell lines. DPT-C9h also induced significant TGI in BC xenografts models. The mouse-specific peptide DPT-C9 also induced TGI in lung (K-Ras model) and breast cancer (PyMT) models. DPT-C9h has a specific effect on transformed B cells isolated from chronic lymphocytic leukemia patients without any effect on primary healthy cells. Finally, neither toxicity nor immunogenic responses were observed. CONCLUSION: Using the cell-penetrating peptides blocking caspase-9/PP2A interactions, we have demonstrated that DPT-C9h had a strong therapeutic effect in vitro and in vivo in mouse models of tumour progression.

Differential aiolos expression in human hematopoietic subpopulations.

The Aiolos transcription factor plays a crucial role in the control of lymphocyte differentiation and proliferation. The expression of Aiolos isoform has been studied in lymphoid pathologies but nothing is known about its expression in unaffected human hematopoietic subpopulations. In this manuscript we show for the first time the differential Aiolos expression at the RNA and protein level in hematopoietic cell subpopulations. B cells express higher levels of Aiolos than NK and T cells while monocytes express almost undetectable levels of Aiolos. Moreover, human CD34 (+) progenitors do not express Aiolos. We did not observe significant difference when comparing naive to memory T and B cells, but we observed an important difference between Bright and Dim NK cells. Furthermore, we show that, in addition to hematopoietic cells, non hematopoietic cell lines such as MCF-7, SW480, HEK, PC3 and HeLa also express Aiolos.

The Aiolos transcription factor is up-regulated in chronic lymphocytic leukemia.

The Aiolos transcription factor, member of the Ikaros family of zinc finger proteins, plays an important role in the control of mature B lymphocyte differentiation and proliferation, and its function appears to be modulated through alternative splicing. To assess Aiolos isoform role in humans' pathologies, we studied Aiolos variant distribution and expression in mature B lymphoproliferative disorders (chronic lymphocytic leukemia [CLL] and other B-cell lymphomas). We demonstrated that more than 80% of expressed Aiolos in normal as well as in malignant B cells is of the hAio1 type, and we showed for the first time a homogeneous overexpression of the total amounts of Aiolos transcripts in the B cells of CLL patients, independently of ZAP-70 and IgV(H) mutational status prognosis factors. This up-regulation of Aiolos, confirmed at protein level, seems independent of Aiolos promoter H3K9 acetylation and H3K4 trimethylation.