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APOPTOSIS GENE EXPRESSION IN HUMAN EPDERMAL KERATINOCYTES TREATED WITH SODIUM ARSENITE USING REAL TIME PCR ARRAY
Citation:
MO, J., J. S. MUMFORD, AND Y. XIA. APOPTOSIS GENE EXPRESSION IN HUMAN EPDERMAL KERATINOCYTES TREATED WITH SODIUM ARSENITE USING REAL TIME PCR ARRAY. Presented at Society of Toxicology 47th Annual Meeting, Seattle, WA, March 16 - 20, 2008.
Impact/Purpose:
This study was to investigate arsenic effects on expression of the genes relevant to apoptosis and examine the possible mode of action by arsenic in human cells.
Description:
Arsenic exposure via contaminated drinking water is a great public health concern worldwide. Chronic arsenic exposure has been associated with human skin, lung and bladder cancer and other chronic effects. We have previous reported that sodium arsenite stimulated cell proliferation at low dose (peaked at 0.5 µM), and induced apoptosis at high doses (starting at 1.0 µM and up to 40 µM) in human epidermal keratinocytes (HaCaT). The mechanisms of apoptosis induced by arsenic are not completely understood. This study was to investigate arsenic effects on expression of the genes relevant to apoptosis and examine the possible mode of action by arsenic in human cells. HaCaT cells were treated with 0 µM (controls), 0.5 µM, 1.0 µM and 10 µM of sodium arsenite for 72 hours. Total RNA was isolated and gene expression of 93 genes relevant to apoptosis and 3 endogenous controls was assayed using real time PCR array (Apoptosis Panel of Taqman Low Density Array, ABI). Target gene expression was normalized to 18s RNA and calculated as fold of the controls. The results showed most of apoptosis-related gene expression tested increased at 0.5 µM and 1.0 µM and decreased at 10 µM. The anti-apoptosis genes such as BIRC2 and BIRC3 greatly increased (3.3 and 3.2 folds of control, respectively) at the lowest dose, 0.5 µM, but decreased at 1µM. Whereas, the pro-apoptosis genes such as BAX, PMAIP1 and BNIP3L gradually increased at 0.5 µM and peaked at 1 µM (3.4, 2.0, and 2.4 folds of control, respectively). Other apoptosis-related genes, TNF-α and the NFκB pathway genes (NFκB2, IκBε), also showed dose- response relationships and peaked at 1 µM (5.3, 2.2 and 2.0 folds of control, respectively). These results showed that depending on concentrations, arsenic can function both as anti-apoptotic and apoptotic agent in human cells. (This abstract does not reflect EPA policy.)