The first MCL-1-selective BH3 mimetics have therapeutic potential for chronic lymphocytic leukemia.

Small-molecule BH3 mimetics are designed to mimic the BH3 domain of BH3-only BCL-2 family members which are antagonists of the prosurvival members (such as BCL-2, BCL-XL and MCL-1). The BH3 mimetics are intended to bind with high affinity to prosurvival proteins, in order to inhibit their functional activity and hence to induce apoptosis in cancer cells. Both navitoclax (BCL-2/BCL-XL antagonist) and ABT-199/venetoclax (BCL-2-selective inhibitor) have demonstrated therapeutic efficacy especially in chronic lymphocytic leukemia (CLL).

New dimension in therapeutic targeting of BCL-2 family proteins.

Proteins of the BCL-2 family control the mitochondrial pathway of apoptosis. Targeting these proteins proves to be an attractive strategy for anticancer therapy. The biological context is based on the fact that BH3-only members of the family are specific antagonists of prosurvival members.

Apoptosis inducers in chronic lymphocytic leukemia.

Chronic lymphocytic leukemia (CLL) is characterized by a typical defect in apoptosis and is still an incurable disease. Numerous apoptosis inducers have been described. These synthetic compounds and natural products (mainly derived from plants) display antileukemic properties in vitro and in vivo and some have even been tested in the clinic in CLL.

BH3 mimetics: status of the field and new developments.

Targeting apoptosis is an attractive approach in cancer therapy. The BH3-only proteins of the BCL-2 family (having only the BCL-2 homology domain BH3) can trigger apoptosis by binding to the prosurvival members of this family and neutralizing their functional activity (sequestration of the proapoptotic Bcl-2 family members). The "BH3 mimetic" concept has prompted the development of small molecules capable of mimicking BH3-only proteins and thus inducing apoptosis.

p70S6 kinase is a target of the novel proteasome inhibitor 3,3'-diamino-4'-methoxyflavone during apoptosis in human myeloid tumor cells.

Acute myeloid leukemia (AML) is a deadly disease characterized by the clonal expansion and accumulation of hematopoietic stem cells arrested at various stages of development. Clinical research efforts are currently focusing on targeted therapies that induce apoptosis in AML cells. Herein, the effects and mechanisms of the novel flavone 3,3'-diamino-4'-methoxyflavone (DD1) on AML cell dysfunction were investigated in AML cells (monoblast U937, myelomonocyte OCI-AML3, promyelocyte NB4, myeloblast HL-60) and blood samples from patients with AML.

Development of Noxa-like BH3 mimetics for apoptosis-based therapeutic strategy in chronic lymphocytic leukemia.

Despite real advances made in chemoimmunotherapy, chronic lymphocytic leukemia (CLL) is still an incurable disease. New therapeutic strategies based on the restoration of the cell death program seemed relevant. Some members of the Bcl-2 family are critical players in the defective apoptotic program in CLL cells and/or targets of apoptosis inducers in vitro.

Hyperforin induces apoptosis of chronic lymphocytic leukemia cells through upregulation of the BH3-only protein Noxa.

We previously reported that hyperforin, a phloroglucinol purified from Hypericum perforatum, induces the mitochondrial pathway of caspase-dependent apoptosis in chronic lymphocytic leukemia (CLL) cells ex vivo, and that this effect is associated with upregulation of Noxa, a BH3-only protein of the Bcl-2 family. Here, we investigated the role of this upregulation in the pro-apoptotic activity of hyperforin in the cells of CLL patients and MEC-1 cell line. We found that the increase in Noxa expression is a time- and concentration-dependent effect of hyperforin occurring without change in Noxa mRNA levels.

The BH3-only protein Noxa is stimulated during apoptosis of chronic lymphocytic leukemia cells triggered by M2YN, a new plant-derived extract.

Deficiency of apoptosis is a hallmark of chronic lymphocytic leukemia (CLL) cells. M2Yn is a natural extract from plants of central Asia, identified for its antiangiogenic properties and its ability to block the migration of malignant cells. Here, we report that in vitro treatment of cells derived from CLL patients with M2Yn results in internucleosomal DNA fragmentation, phosphatidylserine externalization, mitochondrial membrane depolarization, caspase-3 activation and cleavage of the caspase substrate PARP-1.

Aminopeptidase-N/CD13 is a potential proapoptotic target in human myeloid tumor cells.

The transmembrane metalloprotease aminopeptidase-N (APN)/CD13 is overexpressed in various solid and hematological malignancies in humans, including acute myeloid leukemia (AML) and is thought to influence tumor progression. Here, we investigated the contribution of APN/CD13 to the regulation of growth and survival processes in AML cells in vitro. Anti-CD13 monoclonal antibodies MY7 and SJ1D1 (which do not inhibit APN activity) and WM15 (an APN-blocking antibody) inhibited the growth of the AML cell line U937 and induced apoptosis, as evidenced by cell accumulation in the sub-G(1) phase, DNA fragmentation, and phosphatidylserine externalization.

Therapeutic activity of two xanthones in a xenograft murine model of human chronic lymphocytic leukemia.

Background: We previously reported that allanxanthone C and macluraxanthone, two xanthones purified from Guttiferae trees, display in vitro antiproliferative and proapoptotic activities in leukemic cells from chronic lymphocytic leukemia (CLL) and leukemia B cell lines.

Results: Here, we investigated the in vivo therapeutic effects of the two xanthones in a xenograft murine model of human CLL, developed by engrafting CD5-transfected chronic leukemia B cells into SCID mice. Treatment of the animals with five daily injections of either allanxanthone C or macluraxanthone resulted in a significant prolongation of their survival as compared to control animals injected with the solvent alone (p = 0.

Stimulation of iNOS expression and apoptosis resistance in B-cell chronic lymphocytic leukemia (B-CLL) cells through engagement of Toll-like receptor 7 (TLR-7) and NF-kappaB activation.

B-CLL cells are characterized by in vivo resistance to apoptosis due, in part, to the presence of an inducible nitric oxide synthase, iNOS, as the NO released plays anti-apoptotic role, notably by inhibiting caspases. The mechanisms leading to spontaneous expression of iNOS in these cells are presently unknown. The restricted use of some V(H) sub-groups and the sequences of the monoclonal immunoglobulins of the B-cell receptor expressed by the leukemia cells suggested that the latter have encountered specific auto-antigens and/or microbial derived antigens.

Flavopiridol-induced iNOS downregulation during apoptosis of chronic lymphocytic leukemia cells is caspase-dependent.

We previously reported that flavopiridol-induced apoptosis of B cell chronic lymphocytic leukemia (CLL) patients' cells ex vivo is associated with downregulation of both the inducible nitric oxide (NO) synthase (iNOS) that produces the antiapoptotic molecule NO, and the CDK inhibitor p27kip1 that is thought to block the cell cycle of CLL cells. Here, we show that iNOS downregulation is caspase-dependent and thus can be considered as one of the effector mechanisms of apoptosis, but not a primary triggering event induced by flavopiridol. Furthermore, we also find that this flavone favors the entry into the S and G2 phases of the cell cycle of a subpopulation of the leukemic cells, confirming that flavopiridol might be useful for improving the efficacy of cell cycle-dependent cytostatic agents in the therapy of CLL.

Hyperforin inhibits P-gp and BCRP activities in chronic lymphocytic leukaemia cells and myeloid cells.

We showed previously that hyperforin (HF), a natural phloroglucinol, stimulated apoptosis in B cell chronic lymphocytic leukaemia cells (CLL) and displayed anti-angiogenic properties. In the present work, we investigated the effects of hyperforin on the activity of P-gp/MDR1, an ABC (ATP-binding cassette) transporter putatively involved in multidrug resistance (MDR). Ex vivo treatment of CLL cells with HF markedly impaired the activity of P-gp, as measured by the inhibition of the capacity of the treated cells to efflux the rhodamine 123 probe.

Role of BAFF and APRIL in human B-cell chronic lymphocytic leukaemia.

B-cell chronic lymphocytic leukaemia (B-CLL) is the most prevalent leukaemia in Western countries and is characterized by the gradual accumulation in patients of small mature B cells. Since the vast majority of tumoral cells are quiescent, the accumulation mostly results from deficient apoptosis rather than from acute proliferation. Although the phenomenon is relevant in vivo, B-CLL cells die rapidly in vitro as a consequence of apoptosis, suggesting a lack of essential growth factors in the culture medium.

The inducible NO synthase is downregulated during apoptosis of malignant cells from B-cell chronic lymphocytic leukemia induced by flavopiridol and polyphenols.

Downregulation of iNOS and NO is a pathway common for flavones and polyphenols, two distinct families of phytoalexins. Our data suggest that inhibition of the NO pathway could be one of the mechanisms involved in the proapoptotic properties of these phytoalexins in leukemia B-cells.

Re-establishment of a normal apoptotic process as a therapeutic approach in B-CLL.

Even though the capacity of B-CLL leukemic cells to proliferate has been underestimated until recently, the accumulation of tumor cells in patients mostly results from a defect in the apoptotic program. Several mechanisms can account for this deficient cell death pathway. These include overexpression of anti-apoptotic molecules such as members of the Bcl-2 family, which control the opening of the mitochondrial transition permeability pore, and of the IAP (inhibitors of apoptosis) family, which inhibit the activity of caspases.

Involvement of BAFF and APRIL in the resistance to apoptosis of B-CLL through an autocrine pathway.

Tumor necrosis factor (TNF) superfamily members BAFF, or B-cell activation factor of the TNF family, and APRIL, a proliferation-inducing ligand, are involved in normal B-cell survival and differentiation. They interact with 3 receptors: BAFF-R, specific to BAFF; and TACI and BCMA, which are shared by BAFF and APRIL. We tested the potential role of these proteins in B-cell chronic lymphocytic leukemia (B-CLL) resistance to apoptosis.

Comparative antiproliferative and apoptotic effects of resveratrol, epsilon-viniferin and vine-shots derived polyphenols (vineatrols) on chronic B lymphocytic leukemia cells and normal human lymphocytes.

Trans-resveratrol, its dimer epsilon-viniferin and two preparations of vineatrol (a grape-derived polyphenol fraction isolated from vine-shots extracts) were compared for their effects on the proliferation and survival of normal and leukemic human lymphocytes. The two different batches of vineatrol (vineatrol 10 and 25%) was obtained by HPLC fractionation and contained 10 and 25% trans-resveratrol, respectively. The different polyphenols were added to cultures of leukemic cells from chronic B cell malignancies (B-cell chronic lymphocytic leukemia, B-CLL or hairy cell leukemia, HCL) or normal peripheral blood-derived mononuclear cells (PBMC) as a control.

Ad-IFN gamma induces antiproliferative and antitumoral responses in malignant mesothelioma.

Purpose: The aim of the work was to investigate the effects of adenovirus(Ad)-mediated IFN gamma gene transfer on human mesothelioma (HM) cell proliferation in vitro and growth in nude mice.

Experimental Design: We constructed an E1E3-deleted replication-defective recombinant Ad carrying the human IFN gamma gene (Ad-IFN gamma) and tested its activity in vitro on HM cell lines established in our laboratory and in a nude mice model.

Results: In vitro, infection of HM cells with Ad-IFN gamma led to a prolonged production of an active cytokine in the 10 HM cell lines tested and also led to an antiproliferative effect on the HM cells previously demonstrated as responsive to exogenous recombinant human IFN gamma.

Analysis of resveratrol-induced apoptosis in human B-cell chronic leukaemia.

Trans-resveratrol was analysed for its apoptotic and growth inhibitory activity in human B-cell lines derived from chronic B-cell malignancies (WSU-CLL and ESKOL), and in leukaemic lymphocytes from patients with B-cell chronic lymphocytic leukaemia (B-CLL). Resveratrol displayed antiproliferative activity on both B-cell lines, as estimated by the decrease in cell recovery and inhibition of thymidine uptake. Furthermore, resveratrol induced apoptosis in the two cell lines as well as in B-CLL patients' cells, as evidenced by the increase in annexin V binding, caspase activation, DNA fragmentation and decrease of the mitochondrial transmembrane potential DeltaPsim.