Partial involvement of c-jun protooncogene in growth enhancing and cytotoxic effects of lithium in vitro
Shai, L.J.; Abotsi, E.K.; Tyobekai, E.M.; Wachira, J.M.
Cellular and Molecular Biology 49(7): 1137-1143
2003
ISSN/ISBN: 0145-5680 PMID: 14682396 Document Number: 559809
The AP-1 transcription factor is comprised of homo- and heterodimers of the Fos and Jun families of proteins. Literature reports indicate that AP-1 is activated in lithium treated mammalian cells suggesting a role in lithium induced growth stimulation and apoptosis. In these studies, an antisense c-jun plasmid blocked the stimulation of HL-60 cell growth by lithium. Furthermore, antisense c-jun caused a 60% reduction in cell viability at 48 hr post-transfection but did not influence DNA fragmentation in the presence of lithium. The levels of c-jun mRNA, as determined by RT-PCR, were not affected by lithium treatment. Nevertheless, 12-O-tetradecanoyl-phorbol-13-acetate (TPA) blocked the induction of apoptosis by lithium suggesting the involvement of the protein kinase C (PKC) signaling pathway. In RAJI cells, antisense c-jun mimicked lithium by inhibiting cell proliferation with only a marginal loss in cell viability. This study therefore suggests that PKC is involved in the effects of lithium on cells in culture and provides evidence for differential effects of antisense c-jun on hemotopoietic lineages.