Runx3, a member of Runt-related
transcription factor (
Runx) proteins with
tumor suppressor effect, is a tissue-restricted and
cancer related
transcription factor that regulate cell proliferation and growth, as well as differentiation. In the present study, exogenous Run3 was transiently expressed in AGS (human gastric
adenocarcinoma), with undetectable
Runx3 protein and in A549 (human lung
carcinoma) with low levels of endogenous
Runx3 protein. The GFP tagged Runx3 was transfected into AGS and A549 cells using fugene6 and PolyFect and Runx3 expression was confirmed by fluorescent microscopy and RT-PCR. The effect of Runx3 transfection on cell proliferation was determined by MTT assay and the results were confirmed by the
trypan blue dye exclusion method. The effect of Runx3 expression on
mRNA expression of
BCL2-associated X protein (Bax) was evaluated using RT-PCR. In AGS and A549 cells, Runx3 expression inhibited cell proliferation (p < 0.01). The growth inhibition was less in A549 cells. We show that Runx3 expression increases Bax
mRNA expression in AGS cells when compared with control (p < 0.05), but no significant differences in
mRNA expression was observed in both examined cells. Runx3 expression has antiproliferative effect in AGS cell perhaps via increase in expression of Bax. The effect of Runx3 on A549 cells' viability which has endogenous level of Runx3 is not related to Bax. These findings implicate a complex regulation by Runx3 in inhibition of cell proliferation utilizing Bax.