Inhibition of Kirsten-ras expression in human colorectal cancer using rationally selected Kirsten-ras antisense oligonucleotides.
Kirsten-ras is frequently mutated in colorectal cancers and may be an important therapeutic target, particularly because we have previously shown that acquisition of a mutation is associated with a poorer outcome. Understanding the role of Kirsten-ras and the consequences of inhibiting its activity or expression will contribute to our comprehension of colorectal cancer biology and may help to rationalize the choice of molecular targets suitable for therapeutic manipulation. Therefore we undertook a simple screen, incubating a library of oligonucleotides with Kirsten-ras mRNA and RNase H to identify an antisense oligonucleotide that effectively inhibited Kirsten-ras expression. We show for the first time in a human colon cancer cell line that inhibition of Kirsten-ras expression inhibits constitutive phosphorylation of Erk1/2, but not c-Akt, suggesting that in these cells constitutive phosphorylation of Erk 1/2 is dependent upon Kirsten-ras. Successful inhibition of Kirsten-ras had little effect on cell number or cell death and there was no evidence for accumulation of cells in any particular phase of the cell cycle. Kirsten-ras inhibition significantly reduced secretion of VEGF-A165 into the culture medium. Gene expression profiling by microarray detected altered expression of a number of genes. Of particular interest for future studies was the altered expression of genes encoding products involved in protein trafficking and the potential effects of these changes on cell adhesion. Our results suggest that, at least in this model, Kirsten-ras may contribute to malignancy predominantly through effects on angiogenesis, invasion, and metastasis, and that therapies directed at Kirsten-ras, including antisense approaches, may have particular utility through these mechanisms.
Ross
P J
PJ
Cancer Research Campaign Centre for Cancer Therapeutics, Institute of Cancer Research, 15 Cotswold Road, Sutton, Surrey, SM2 5NG, United Kingdom.
George
M
M
Cunningham
D
D
DiStefano
F
F
Andreyev
H J
HJ
Workman
P
P
Clarke
P A
PA
D000230:Adenocarcinoma / Q000235:genetics / Q000378:metabolism*; D043925:Angiogenesis Inducing Agents / Q000378:metabolism; D015153:Blotting, Western; D015179:Colorectal Neoplasms / Q000235:genetics / Q000378:metabolism*; D019938:Cyclin D1 / Q000378:metabolism; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D016376:Oligonucleotides, Antisense / Q000494:pharmacology*; D010766:Phosphorylation; D017354:Point Mutation; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D016283:Proto-Oncogene Proteins p21(ras); D012333:RNA, Messenger / Q000235:genetics; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A; D018631:ras Proteins
D043925:Angiogenesis Inducing Agents; C117307:KRAS protein, human; D016376:Oligonucleotides, Antisense; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D019938:Cyclin D1; C494918:AKT1 protein, human; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins