Molecular analysis of apoptosis pathway after photodynamic therapy in breast cancer: Animal model study
PHOTODIAGNOSIS AND PHOTODYNAMIC THERAPY
Authors: Silva, Luciana C.; Ferreira-Strixino, Juliana; Fontana, Leticia C.; Rocha Gonsalves, Antonio M. d'A.; Serra, Armenio C.; Pineiro, Marta; Canevari, Renata A.
Abstract
Background: Molecular investigation of breast tumors has permitted better understanding about interaction of genes and pathways involved in tumor progression. Objective: The aim of this study was to evaluate the association between genes belonging to the pathway of apoptosis with tumor response to photodynamic therapy. Study Design/Materials and methods: The mammary tumors were induced in twenty-four Spraguey-Dawley female rats by oral gavage of 7,12-dimethylbenz(a)anthracene (8 mg/Kg body weight). Animals were divided into three groups: G1 (normal tissue), G2 (tumors without treatment), G3 (animals euthanized 48 h after treatment). The photosensitizer used was a chlorin, 5,15-bis-(2-bromo-5-hydroxyphenyl) chlorin in the dose of 8 mg/kg for each animal. Light source of diode laser at a wavelength of 660 nm, fluence rate of 100 mW/cm, and light dose of 100 J/cm was delivery to lesions for treatment. A sample from each animal was investigated by quantitative real time PCR using Rat Apoptosis RT2 Profiler (TM) PCR Array platform. Results: Pro-apoptotic BAK1, CARD6, CASP8, CIDEA, CIDEB, DAPK1, TNF, TNFRSF10B, FASLG, LOC687813, and TP73 genes showed increased expression, and CD40 anti-apoptotic gene showed decreased expression in the group who underwent PDT (G3) in relation to G2. Conclusion: The results indicated that these genes are involved more directly with cellular apoptosis induced by PDT using the Chlorin photosensitizer. (C) 2016 Elsevier B.V. All rights reserved.
Next-generation hypomethylating agent SGI-110 primes acute myeloid leukemia cells to IAP antagonist by activating extrinsic and intrinsic apoptosis pathways
CELL DEATH AND DIFFERENTIATION
Authors: Dittman, Jessica; Haydn, Tinka; Metzger, Patrick; Ward, George A.; Boerries, Melanie; Vogler, Meike; Fulda, Simone
Abstract
Therapeutic efficacy of first-generation hypomethylating agents (HMAs) is limited in elderly acute myeloid leukemia (AML) patients. Therefore, combination strategies with targeted therapies are urgently needed. Here, we discover that priming with SGI-110 (guadecitabine), a next-generation HMA, sensitizes AML cells to ASTX660, a novel antagonist of cellular inhibitor of apoptosis protein 1 and 2 (cIAP1/2) and X-linked IAP (XIAP). Importantly, SGI-110 and ASTX660 synergistically induced cell death in a panel of AML cell lines as well as in primary AML samples while largely sparing normal CD34+ human progenitor cells, underlining the translational relevance of this combination. Unbiased transcriptome analysis revealed that SGI-110 alone or in combination with ASTX660 upregulated the expression of key regulators of both extrinsic and intrinsic apoptosis signaling pathways such as TNFRSF10B (DR5), FAS, and BAX. Individual knockdown of the death receptors TNFR1, DR5, and FAS significantly reduced SGI-110/ASTX660-mediated cell death, whereas blocking antibodies for tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) or FAS ligand (FASLG) failed to provide protection. Also, TNF alpha-blocking antibody Enbrel had little protective effect on SGI-110/ASTX660-induced cell death. Further, SGI-110 and ASTX660 acted in concert to promote cleavage of caspase-8 and BID, thereby providing a link between extrinsic and intrinsic apoptotic pathways. Consistently, sequential treatment with SGI-110 and ASTX660-triggered loss of mitochondrial membrane potential (MMP) and BAX activation which contributes to cell death, as BAX silencing significantly protected from SGI-110/ASTX660-mediated apoptosis. Together, these events culminated in the activation of caspases-3/-7, nuclear fragmentation, and cell death. In conclusion, SGI-110 and ASTX660 cooperatively induced apoptosis in AML cells by engaging extrinsic and intrinsic apoptosis pathways, highlighting the therapeutic potential of this combination for AML.