Antisense inhibition of protein kinase Calpha reverses the transformed phenotype in human lung carcinoma cells.
The protein kinase C (PKC) family, which functions through serine/threonine kinase activity, is involved in signal transduction pathways necessary for cell proliferation and differentiation. Its critical role in processes relevant to neoplastic transformation and tumor invasion renders PKC a potentially suitable target for anticancer therapy. To explore whether antisense blocking of PKCalpha would inhibit the neoplastic properties in tumor cells, human lung carcinoma LTEPa-2 cells were transfected with a recombinant plasmid, pXJ41-CKPalpha, with PKCalpha cDNA inserted in the antisense orientation. In LT.AS4 cell clones stably expressing antisense PKCalpha mRNA, the amounts of PKCalpha protein and total PKC activity were decreased when compared to control cells. The expression of antisense PKCalpha markedly inhibited the cell proliferation rate, colony forming efficiency in soft agar, and tumorigenecity in nude mice. Furthermore, the mRNA levels of oncogenes (Ha-ras, c-jun, and c-fos) were seen to decrease to varying degrees. Reduced DNA binding activity of transcription factor AP-1 was also observed using gel shift analysis, suggesting that one major molecular mechanism by which PKCalpha can exert its effects on cell growth and transformation is through regulation of AP-1 transcription factor activity. Taken together, these data provide evidence for the ability of antisense PKCalpha expression to reverse the transformed phenotype of human lung carcinoma cells and support the development of PKCalpha inhibitors for the clinical treatment of cancers.
Wang
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The Key Laboratory of Cell Proliferation and Regulation Biology, Beijing Normal University, Beijing, 100875, P. R. China. xywang@sc3101.med.buffalo.edu
Repasky
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Liu
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D000818:Animals; D002455:Cell Division; D002471:Cell Transformation, Neoplastic; D015536:Down-Regulation; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D015870:Gene Expression; D006801:Humans; D007527:Isoenzymes / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D008175:Lung Neoplasms / Q000188:drug therapy / Q000201:enzymology*; D051379:Mice; D008819:Mice, Nude; D016376:Oligonucleotides, Antisense / Q000494:pharmacology*; D010641:Phenotype; D011493:Protein Kinase C / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D051571:Protein Kinase C-alpha; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics; D016755:Proto-Oncogene Proteins c-jun / Q000235:genetics; D016283:Proto-Oncogene Proteins p21(ras) / Q000235:genetics; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014407:Tumor Cells, Cultured
D004791:Enzyme Inhibitors; D007527:Isoenzymes; D016376:Oligonucleotides, Antisense; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D018808:Transcription Factor AP-1; C496628:PRKCA protein, human; C496630:Prkca protein, mouse; D011493:Protein Kinase C; D051571:Protein Kinase C-alpha; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras)