title: Unusual roles of caspase-8 in triple-negative breast cancer cell line MDA-MB-231.
abstract: Triple-negative breast cancer (TNBC) is a clinically aggressive form of breast cancer that is unresponsive to endocrine agents or trastuzumab. TNBC accounts for ~10-20% of all breast cancer cases and represents the form with the poorest prognosis. Patients with TNBC are at higher risk of early recurrence, mainly in the lungs, brain and soft tissue, therefore, there is an urgent need for new therapies. The present study was carried out in MDA-MB-231 cells, where we assessed the role of caspase-8 (casp-8), a critical effector of death receptors, also involved in non‑apoptotic functions. Analysis of casp-8 mRNA and protein levels indicated that they were up-regulated with respect to the normal human mammalian epithelial cells. We demonstrated that silencing of casp-8 by small interfering-RNA, strongly decreased MDA-MB-231 cell growth by delaying G0/G1- to S-phase transition and increasing p21, p27 and hypo-phosphorylated/active form of pRb levels. Surprisingly, casp-8-knockdown, also potently increased both the migratory and metastatic capacity of MDA-MB‑231 cells, as shown by both wound healing and Matrigel assay, and by the expression of a number of related-genes and/or proteins such as VEGFA, C-MYC, CTNNB1, HMGA2, CXCR4, KLF4, VERSICAN V1 and MMP2. Among these, KLF4, a transcriptional factor with a dual role (activator and repressor), seemed to play critical roles. We suggest that in MDA-MB‑231 cells, the endogenous expression of casp-8 might keep the cells perpetually cycling through downregulation of KLF4, the subsequent lowering of p21 and p27, and the inactivation by hyperphosphorylation of pRb. Simultaneously, by lowering the expression of some migratory and invasive genes, casp-8 might restrain the metastatic ability of the cells. Overall, our findings showed that, in MDA-MB-231 cells, casp-8 might play some unusual roles which should be better explored, in order to understand whether it might be identified as a molecular therapeutic target.
authors.affiliation: Laboratory of Biochemistry, Department of Biological, Chemical and Pharmaceutical Sciences and Technologies, University of Palermo, Polyclinic, Palermo, Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: De Blasio
authors.affiliation: Laboratory of Biochemistry, Department of Biological, Chemical and Pharmaceutical Sciences and Technologies, University of Palermo, Polyclinic, Palermo, Italy.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Di Fiore
authors.affiliation: Laboratory of Biochemistry, Department of Biological, Chemical and Pharmaceutical Sciences and Technologies, University of Palermo, Polyclinic, Palermo, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Morreale
authors.affiliation: Laboratory of Biochemistry, Department of Experimental Biomedicine and Clinical Neurosciences, University of Palermo, Polyclinic, Palermo, Italy.
authors.forename: Daniela
authors.initials: D
authors.lastname: Carlisi
authors.affiliation: Laboratory of Biochemistry, Department of Biological, Chemical and Pharmaceutical Sciences and Technologies, University of Palermo, Polyclinic, Palermo, Italy.
authors.forename: Rosa
authors.initials: R
authors.lastname: Drago-Ferrante
authors.affiliation: Laboratory of Biochemistry, Department of Experimental Biomedicine and Clinical Neurosciences, University of Palermo, Polyclinic, Palermo, Italy.
authors.forename: Mauro
authors.initials: M
authors.lastname: Montalbano
authors.affiliation: Department of Physiology and Biochemistry, University of Malta, Msida, Malta.
authors.forename: Christian
authors.initials: C
authors.lastname: Scerri
authors.affiliation: Sbarro Institute for Cancer Research and Molecular Medicine, Center for Biotechnology, Temple University, Philadelphia, PA, USA.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Tesoriere
authors.affiliation: Laboratory of Biochemistry, Department of Biological, Chemical and Pharmaceutical Sciences and Technologies, University of Palermo, Polyclinic, Palermo, Italy.
authors.forename: Renza
authors.initials: R
authors.lastname: Vento
mesh_terms: D053181:Caspase 8 / Q000235:genetics / Q000378:metabolism*; D002453:Cell Cycle / Q000502:physiology; D045744:Cell Line, Tumor; D015536:Down-Regulation; D005260:Female; D016193:G1 Phase / Q000502:physiology; D006801:Humans; D000090062:Kruppel-Like Factor 4; D034741:RNA, Small Interfering / Q000008:administration & dosage / Q000235:genetics; D016192:Resting Phase, Cell Cycle / Q000502:physiology; D014162:Transfection; D064726:Triple Negative Breast Neoplasms / Q000201:enzymology* / Q000235:genetics / Q000473:pathology
chemical_list: C000715467:KLF4 protein, human; D000090062:Kruppel-Like Factor 4; D034741:RNA, Small Interfering; C505530:CASP8 protein, human; D053181:Caspase 8