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The acute promyelocytic leukemia (APL) subtype of acute myeloid leukemia (AML) is characterized by chromosomal translocations that result in fusion proteins, including the promyelocytic leukemia-retinoic acid receptor, alpha fusion protein (PML-RARα). All-trans retinoic acid (atRA) treatment is the standard drug treatment for APL yielding cure rates > 80% by activating transcription and proteasomal degradation of retinoic acid receptor, alpha (RARα). Whereas combination therapy with As2O3 has increased survival further, patients that experience relapse and are refractory to atRA and/or As2O3 is a clinically significant problem. BCL-2 family proteins regulate apoptosis and over-expression of anti-apoptotic B-cell leukemia/lymphoma 2 (BCL-2) family proteins has been associated with chemotherapeutic resistance in APL including impairment of the ability of atRA to induce growth arrest and differentiation. Here we investigated the novel BH3 domain mimetic, JY-1-106, which antagonizes the anti-apoptotic BCL-2 family members B-cell lymphoma-extra large (BCL-xL) and myeloid cell leukemia-1 (MCL-1) alone and in combination with retinoids including atRA, AM580 (RARα agonist), and SR11253 (RARγ antagonist). JY-1-106 reduced cell viability in HL-60 cells alone and in combination with retinoids. The combination of JY-1-106 and SR11253 had the greatest impact on cell viability by stimulating apoptosis. These studies indicate that dual BCL-xL/MCL-1 inhibitors and retinoids could work cooperatively in leukemia treatment., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Ligand activation of peroxisome proliferator-activated receptor (PPAR)gamma and retinoid X receptor (RXR) induces antitumor effects in cancer. We evaluated the ability of combined treatment with nanomolar levels of the PPARgamma ligand rosiglitazone (BRL) and the RXR ligand 9-cis-retinoic acid (9RA) to promote antiproliferative effects in breast cancer cells. BRL and 9RA in combination strongly inhibit of cell viability in MCF-7, MCF-7TR1, SKBR-3, and T-47D breast cancer cells, whereas MCF-10 normal breast epithelial cells are unaffected. In MCF-7 cells, combined treatment with BRL and 9RA up-regulated mRNA and protein levels of both the tumor suppressor p53 and its effector p21(WAF1/Cip1). Functional experiments indicate that the nuclear factor-kappaB site in the p53 promoter is required for the transcriptional response to BRL plus 9RA. We observed that the intrinsic apoptotic pathway in MCF-7 cells displays an ordinated sequence of events, including disruption of mitochondrial membrane potential, release of cytochrome c, strong caspase 9 activation, and, finally, DNA fragmentation. An expression vector for p53 antisense abrogated the biological effect of both ligands, which implicates involvement of p53 in PPARgamma/RXR-dependent activity in all of the human breast malignant cell lines tested. Taken together, our results suggest that multidrug regimens including a combination of PPARgamma and RXR ligands may provide a therapeutic advantage in breast cancer treatment.

In addition to playing a fundamental role in diverse processes, such as vision, growth and differentiation, vitamin A and its main biologically active derivative, retinoic acid (RA), are clearly involved in the regulation of testicular functions. The present study was undertaken to examine the direct effect of RA treatment on Leydig (TM-3) cells. TM-3 cells were cultured and treated with varying concentrations of RA for 24h. High doses of RA (1-20microM) induced a decrease in cell vitality and an increase in lipid peroxidation. RA treatment also induced a corresponding increase in apoptosis in the same cells in a dose-dependent manner. Apoptosis proceeded via the mitochondrial dependent pathway, as demonstrated by the release of cytochrome c, caspase-3 enzymatic activation and DNA fragmentation. Conversely, at physiological doses (0.1-500nM) RA did not increase lipid peroxidation or cell death and resulted in an increase of antioxidant enzyme activity.

Ferulic acid plays a chemopreventive role in cancer by inducing tumor cells apoptosis. As mitochondria play a key role in the induction of apoptosis in many cells types, here we investigate the mitochondrial permeability transition (MPT) and the release of cytochrome c induced by ferulic acid and its esters in rat testes mitochondria, in TM-3 and MLTC-1 cells. While ferulic acid, but not its esters, induced MPT and cytochrome c release in rat testes isolated mitochondria, in TM-3 cells we found that both ferulic acid and its esters induced cytochrome c release from mitochondria in a dose-dependent manner, suggesting a potential target of these compounds in the induction of cell apoptosis. The apoptosis induced by ferulic acid is therefore associated with the mitochondrial pathway involving cytochrome c release and caspase-3 activation.