EXPRESSION OF ANTISENSE PC1 IN STABLY TRANSFECTED RIN5F CELLS SIGNIFICANTLY REDUCES CCK-8 BIOSYNTHESIS

The subtilisin-like endoprotease PC1 (PC3) has been implicated in the processing of a number of prohormones. To evaluate whether PC1 may be important for the processing of pro CCK to CCK 8, stable cell lines expressing a portion of the PC1 cDNA in the antisense orientation were established from RIN5F cells. These cells express CCK mRNA, produce and display regulated secretion of CCK 8. One of the clones, R1E8, expresses antisense PC1 mRNA as determined by reverse transcriptase-PCR (RT-PCR) and contains a significantly reduced level of PC1 protein. As compared to both RIN5F and RIN5F control cells (transfected with the expression plasmid containing no antisense message), R1E8 contains only about 30% cell content of CCK 8. These results suggest that PC1 may be important for the processing of CCK 8 from pro CCK.