The objective of the present study was to investigate the effect of β-lapachone, a quinone obtained from the bark of the lapacho tree (Tabebuia avellanedae), on the cell growth and apoptosis in human lung carcinoma cell line A549. Exposure of A549 cells to β-lapachone resulted in growth inhibition and induction of apoptosis in a time- and dose-dependent manner as measured by hemocytometer counts, fluorescence microscopy and flow cytometry analysis. This increase in apoptosis was associated with a decrease in Bcl-2 and expression, an increase of Bax, and an activation of caspase-3 and caspase-9. β-lapachone treatment markedly inhibited the activity of telomerase in a dose-dependent fashion. Additionally, the levels of human telomerase RNA (hTR) and c-myc expression were progressively down-regulated by β-lapachone treatment. Taken together, these findings provide important new insights into the possible molecular mechanisms of the anti-cancer activity of β-lapachone.

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