title: Apoptosis-related protein-2 triggers melanoma cell death by a mechanism including both endoplasmic reticulum stress and mitochondrial dysregulation.
abstract: Metastatic cancers including melanoma are frequently associated with increased resistance to apoptosis induced by various therapeutic modalities, and the success of systemic therapy for the treatment of metastatic melanoma is minimal. In the present study, we demonstrated the ability of apoptosis-related protein (APR)-2 to trigger cell death via mechanism mediated by both endoplasmic reticulum (ER) stress [as evidenced by the increase of intracellular Ca(2+) release, the activation of both, inositol-requiring enzyme 1α (IRE1α) and calpain and cleavage of caspase-4] and mitochondrial dysregulation as evidenced by the loss of mitochondrial membrane potential, Cytochrome c release and cleavage of caspases-9 and -3, and poly adenosine diphosphate ribose polymerase (PARP). Also, the activation of apoptosis signal-regulating kinase (ASK) 1, c-jun-N-terminal kinase (JNK) and the transcription factors AP-1 and p53, and the induction of Bax expression were noted in APR-2-expressing cells. Both immune fluorescence staining and western blotting revealed the localization of APR-2 at ER and Bax protein at both mitochondria and ER. However, data of inhibitory experiments demonstrated that APR-2-induced apoptosis of melanoma cells is mediated by three parallel pathways: one of them IRE1/tumour necrosis factor receptor-associated factor 2/ASK1/JNK/Cyt.c/caspase-9/caspase-3/PARP) seems to be mitochondrial dependent, whereas, the other two pathways namely calpain/caspase-4/caspase-9/caspase-3/PARP and protein kinase RNA-like ER kinase/ATF4/C/EBP homologous protein (CHOP)/Bim seem to be mitochondrial independent. In conclusion, our data provide insight into the molecular mechanism of APR-2-induced apoptosis and suggest APR-2 gene transfer as an alternative approach for the treatment of chemoresistance melanoma metastasis.
authors.affiliation: INSERM U977, and Department of Operative Dentistry and Endodontics, Dental Faculty, University of Strasbourg, Strasbourg, France.
authors.forename: Denis
authors.initials: D
authors.lastname: Selimovic
authors.forename: Mutmid
authors.initials: M
authors.lastname: Ahmad
authors.forename: Abdelouahid
authors.initials: A
authors.lastname: El-Khattouti
authors.forename: Matthias
authors.initials: M
authors.lastname: Hannig
authors.forename: Youssef
authors.initials: Y
authors.lastname: Haïkel
authors.forename: Mohamed
authors.initials: M
authors.lastname: Hassan
mesh_terms: D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism*; D015153:Blotting, Western; D020169:Caspases / Q000378:metabolism; D049109:Cell Proliferation; D002478:Cells, Cultured; D045304:Cytochromes c / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D004721:Endoplasmic Reticulum / Q000473:pathology*; D005347:Fibroblasts / Q000378:metabolism; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D008545:Melanoma / Q000378:metabolism* / Q000473:pathology*; D053078:Membrane Potential, Mitochondrial; D008928:Mitochondria / Q000473:pathology*; D015398:Signal Transduction; D051028:bcl-2-Associated X Protein / Q000378:metabolism
chemical_list: D051017:Apoptosis Regulatory Proteins; D051028:bcl-2-Associated X Protein; D045304:Cytochromes c; D048031:JNK Mitogen-Activated Protein Kinases; D020169:Caspases