IDENTIFICATION AND INITIAL CHARACTERIZATION OF STATHMIN BY THE DIFFERENTIAL DISPLAY METHOD IN NERVE GROWTH FACTOR-TREATED PC12 CELLS

The differential display of mRNA is a new strategy to identify genes t hat are differentially expressed under altered conditions, We applied this method to determine differential gene expression in the rat pheoc hromocytoma cell line during differentiation induced by nerve growth f actor (NGF). Three different mRNA species were isolated, and their dif ferential expression was confirmed by RT-PCR. One of the mRNA species was identified as stathmin, a 19 kDa cytosolic protein attracting incr easing interest for its role in signal transduction. In the NGF-treate d PC12 cells, the expression of stathmin mRNA increased in a time-depe ndent manner, as assessed by northern blot analysis and RT-PCR. We als o assessed by northern blot analysis how the expression of stathmin mR NA was altered in human pheochromocytomas (n = 5) compared with that i n normal adrenal medulla tissue (n = 5), The mRNA concentrations were found to be significantly greater in the pheochromocytomas than in the normal tissues. It has been shown that stathmin mRNA concentrations a re increased in various tumor cells. As pheochromocytomas are well-dif ferentiated tumors of neural origin, it is not unexpected that stathmi n mRNA is overexpressed in these tumors. Stathmin was isolated and ide ntified as a differentially expressed gene by the differential display method in PC12 cells during differentiation induced by NGF. In additi on, stathmin mRNA was found to be overexpressed in human pheochromocyt omas, The mechanisms responsible for the up-regulation of stathmin mRN A during differentiation of PC12. cells and the significance of its ov erexpression in human pheochromocytomas remain to be determined.