EPINEPHRINE INDUCES CYTOSOLIC TRANSIENTS IN TRANSFORMED KERATINOCYTES

Epinephrine is known to activate beta-adrenergic signal transduction i n human keratinocytes. This, in turn, induces a rise in intracellular calcium, a second messenger which is important for cell proliferation and differentiation. Epinephrine at a concentration of 10 mu M has bee n shown to stimulate an increase in free cytostolic calcium in normal keratinocytes. In this study, eve demonstrate an increase in the fluor escence of calcium-sensitive Flue 3 dye-loaded KB oral epidermoid carc inoma cells (which are transformed keratinocytes) in response to 10 mu M epinephrine, with the aid of laser scanning confocal microscopy. Th is is in contrast to ras transformed NIH3T3 fibroblasts where only 3% of the cell population exhibited calcium transients when stimulated wi th 100 mu M epinephrine. Beta-adrenergic transduction pathways, mediat ed via bronchodilators such as epinephrine, have been postulated as a major factor contributing to the increased incidence of lung periphera l adenocarcinoma. Since beta-adrenergic receptors are present in oral epidermoid carcinoma cells, a possible linkage may also exist between such tumours and the usage of bronchodilators.