Antisense-fos RNA causes partial reversion of the transformed phenotypes induced by the c-Ha-ras oncogene.
Several lines of evidence have suggested that c-fos may act downstream from c-Ha-ras in a growth-regulatory signal transduction pathway. We used antisense RNA to inhibit c-fos gene expression and investigated the effects of diminished c-fos expression on the phenotypes induced by the EJ c-Ha-ras oncogene in NIH 3T3 cells. Immunofluorescent staining demonstrated that the antisense RNA caused a marked reduction in the amount of c-fos protein expressed following serum stimulation. EJ cells containing antisense-fos RNA continued to overexpress ras and remained capable of proliferating in vitro. However, the antisense-fos RNA caused a partial reversion of the major transformed phenotypes of EJ cells, including a restoration of both density-dependent growth arrest and the ability to be rendered quiescent by serum deprivation, a reversion to a flat morphology, inhibition of anchorage-independent growth, and inhibition of tumorigenicity in nude mice. Our results indicate that inhibition of c-fos expression, to a level still supporting in vitro proliferation, prevents the transforming effects of the ras oncogene; they thus provide additional evidence for the participation of c-fos in ras-regulated signal transduction pathways.
Merck Sharp & Dohme Research Laboratories, West Point, Pennsylvania 19486.
B J
BJ
Ledwith
S
S
Manam
A R
AR
Kraynak
W W
WW
Nichols
M O
MO
Bradley
D000818:Animals; D015139:Blotting, Southern; D002455:Cell Division; D002460:Cell Line; D002471:Cell Transformation, Neoplastic; D002478:Cells, Cultured; D004261:DNA Replication; D004273:DNA, Neoplasm / Q000235:genetics; D003907:Dexamethasone / Q000494:pharmacology; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D011905:Genes, ras; D006801:Humans; D007700:Kinetics; D051379:Mice; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D010641:Phenotype; D011505:Protein-Tyrosine Kinases / Q000235:genetics; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D016760:Proto-Oncogene Proteins c-fos; D011519:Proto-Oncogenes; D012313:RNA / Q000235:genetics*; D016372:RNA, Antisense; D012333:RNA, Messenger / Q000037:antagonists & inhibitors*; D014162:Transfection; D014183:Transplantation, Heterologous; D001749:Urinary Bladder Neoplasms / Q000235:genetics
D004273:DNA, Neoplasm; D011518:Proto-Oncogene Proteins; D016760:Proto-Oncogene Proteins c-fos; D016372:RNA, Antisense; D012333:RNA, Messenger; D012313:RNA; D003907:Dexamethasone; D011505:Protein-Tyrosine Kinases