PEITC-mediated inhibition of mRNA translation is associated with both inhibition of mTORC1 and increased eIF2α phosphorylation in established cell lines and primary human leukemia cells.
Increased mRNA translation drives carcinogenesis and is an attractive target for the development of new anti-cancer drugs. In this work, we investigated effects of phenethylisothiocyanate (PEITC), a phytochemical with chemopreventive and anti-cancer activity, on mRNA translation. PEITC rapidly inhibited global mRNA translation in human breast cancer-derived MCF7 cells and mouse embryonic fibroblasts (MEFs). In addition to the known inhibitory effects of PEITC on mTORC1 activity, we demonstrate that PEITC increased eIF2α phosphorylation. PEITC also increased formation of stress granules which are typically associated with eIF2α phosphorylation and accumulation of translationally stalled mRNAs. Analysis of genetically modified MEFs demonstrated that optimal inhibition of global mRNA translation by PEITC was dependent on eIF2α phosphorylation, but not mTORC1 inhibition. We extended this study into primary leukemic B cells derived from patients with chronic lymphocytic leukaemia (CLL). CLL cells were stimulated in vitro with anti-IgM to mimic binding of antigen, a major driver of this leukemia. In CLL cells, PEITC increased eIF2α phosphorylation, inhibited anti-IgM-induced mTORC1 activation and decreased both basal and anti-IgM-induced global mRNA translation. PEITC also inhibited transcription and translation of MYC mRNA and accumulation of the MYC oncoprotein, in anti-IgM-stimulated cells. Moreover, treatment of CLL cells with PEITC and the BTK kinase inhibitor ibrutinib decreased anti-IgM-induced translation and induced cell death to a greater extent than either agent alone. Therefore, PEITC can inhibit both global and mRNA specific translation (including MYC) via effects on multiple regulatory pathways. Inhibition of mRNA translation may contribute to the chemopreventive and anti-cancer effects of PEITC.
['Yeomans|Alison|A|', 'Lemm|Elizabeth|E|', 'Wilmore|Sarah|S|', 'Cavell|Breeze E|BE|', 'Valle-Argos|Beatriz|B|', 'Krysov|Sergey|S|', 'Hidalgo|Marina Sanchez|MS|', 'Leonard|Elodie|E|', 'Willis|Anne E|AE|', 'Forconi|Francesco|F|', 'Stevenson|Freda K|FK|', 'Steele|Andrew J|AJ|', 'Coldwell|Mark J|MJ|', 'Packham|Graham|G|']
D000888:Antibodies, Anti-Idiotypic D045744:Cell Line, Tumor D002470:Cell Survival D004305:Dose-Response Relationship, Drug D015852:Eukaryotic Initiation Factor-2 D015973:Gene Expression Regulation, Leukemic D016259:Genes, myc D006801:Humans D017879:Isothiocyanates D007938:Leukemia D015451:Leukemia, Lymphocytic, Chronic, B-Cell D061986:MCF-7 Cells D000076222:Mechanistic Target of Rapamycin Complex 1 D010766:Phosphorylation D014176:Protein Biosynthesis D012333:RNA, Messenger D011947:Receptors, Antigen, B-Cell D013312:Stress, Physiological D014158:Transcription, Genetic
mRNA translation mTORC1 eIF2α phenethylisothiocyanate MYC