title: Fumonisin B₁ inhibits apoptosis in HepG2 cells by inducing Birc-8/ILP-2.
abstract: Fumonisin B1 (FB1) is a mycotoxin produced by Fusarium sp., a common contaminant of maize. FB1 inhibits sphingolipid biosynthesis, alters sphingosine/sphinganine ratios and modifies cell survival and cell death processes at varying propensities at both species- and tissue-specific level. We investigated the effect of FB1 on the apoptotic pathway in human hepatoma (HepG2) cells. We measured: (i) the level of cell proliferation and cell death mechanism of HepG2 cells (MTT assay, annexin V and propidium iodide staining, JC-1 assay, γH2AX and cleaved PARP and Hoechst staining); (ii) initiator and executioner caspase activity (luminometric enzyme activity assays); (iii) regulation of mRNA expression of pro- and anti- apoptotic molecules using an apoptosis array (qPCR) and (iv) levels of significantly altered apoptosis-related proteins (Western blotting) following a 24 h incubation. FB1 caused a dose-dependent decrease in cell viability with an inhibitory concentration for 50% of cell growth at 200 μM. FACS data showed FB1 induced a 2.5-fold increase in annexin V staining, however, caspase activity and mitochondrial depolarization was not significantly influenced. Cleaved PARP and γH2AX were significantly lower in treated cells with minimal DNA condensation and fragmentation observed with the Hoechst stain. BIRC-8/ILP-2 was most significantly up-regulated (8-fold; apoptosis array). ILP2 protein levels were elevated (2.3-fold) with a corresponding decrease in Smac/DIABLO protein levels (1.7-fold). Further analysis showed a dose-dependent increase in BIRC-8/ILP-2 mRNA and protein expression in HepG2 cells. We conclude that FB1 modulates apoptosis in a complex dose-dependent regulation of pro- and anti-apoptotic molecules.
authors: Discipline of Medical Biochemistry, School of Medical Sciences, University of KwaZulu-Natal, Durban, South Africa. Electronic address: chutur@ukzn.ac.za.
authors: Anil A
authors: AA
authors: Chuturgoon
authors: Discipline of Medical Biochemistry, School of Medical Sciences, University of KwaZulu-Natal, Durban, South Africa. Electronic address: PhulukdareePhulukdaree@ukzn.ac.za.
authors: Alisa
authors: A
authors: Phulukdaree
authors: Discipline of Medical Biochemistry, School of Medical Sciences, University of KwaZulu-Natal, Durban, South Africa. Electronic address: MoodleyDevan_Moodley@hms.harvard.edu.
authors: Devapregasan
authors: D
authors: Moodley
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D053938:DNA Fragmentation; D004305:Dose-Response Relationship, Drug; D037341:Fumonisins / Q000633:toxicity*; D056945:Hep G2 Cells; D006657:Histones / Q000378:metabolism; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins / Q000235:genetics / Q000378:metabolism*; D020128:Inhibitory Concentration 50; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D008099:Liver / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism; D009183:Mycotoxins / Q000633:toxicity*; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D015854:Up-Regulation
chemical_list: D051017:Apoptosis Regulatory Proteins; C430870:BIRC8 protein, human; C412403:DIABLO protein, human; D037341:Fumonisins; C468783:H2AX protein, human; D006657:Histones; D051034:Inhibitor of Apoptosis Proteins; D047908:Intracellular Signaling Peptides and Proteins; D024101:Mitochondrial Proteins; D009183:Mycotoxins; D012333:RNA, Messenger; C056933:fumonisin B1; D011065:Poly(ADP-ribose) Polymerases
keywords: Apoptosis; BIRC-8; Fumonisin B(1); ILP-2; Liver cancer