DIRECTED ANTISENSE THERAPY CONFIRMS THE ROLE OF PROTEIN-KINASE-C-ALPHA IN THE TUMORIGENICITY OF PANCREATIC-CANCER

Background. The level of expression of the alpha isoform of protein, k inase C (PKC-alpha) has been shown to correlate inversely with the pat hologic differentiation of human pancreatic cancers. Methods, We stabl y transfected a moderately differentiated pancreatic cell line (HPAC) to overexpress PKC-alpha and examined the survival rates compared with parent HPAC according to an orthotopic model. Next we used a PKC-alph a antisense oligonucleotide specifically to down-regulate this isoform in vitro and examine the effect of treatment in vivo again according to the orthotopic model. Results. Animals implanted with the overexpre ssing cell line had a mortality rate almost twice that of those implan ted with the parent cell line (P < .01). Treatment with antisense olig onucleotide in increasing concentrations down-regulated PKC-alpha mRNA by Northern blot analysis and reverse transcriptase-polymerase chain reaction. Animals treated with antisense oligonucleotide after orthoto pic implantation of pancreatic cancer cells survived statistically lon ger than those treated with vehicle alone (P = .005). Treatment with a scrambled oligonucleotide also conferred a survival benefit compared with vehicle alone (P < .01). Conclusions. Tumorigenicity of pancreati c cancer is related directly to PKC-alpha expression in vivo as demons trated by decreased survival when overexpressed. PKC-alpha expression can be down-regulated directly (antisense) and indirectly (scrambled) in vitro, which subsequently confers a dramatic survival benefit in vi vo.