Differences in in vitro invasive capacity induced by differences in Ki-Ras protein mutations.
The p21 proteins encoded by N-, Ki-, and H-ras are small guanine nucleotide-binding proteins that act as switches in several signal transduction pathways. Recently, evidence has been accumulating to suggest that valine-12 mutation in the Ki-Ras protein is associated with lung and colorectal tumours that are more aggressive than those carrying aspartate-12 mutation. The purpose of this study was to determine whether cells transfected with different Ki-ras codon-12 mutants have different biological behaviours in vitro that could reflect the differences in behaviour in vivo. For that reason, Rat-1 fibroblasts transfected with the valine-12 or aspartate-12 mutant or the wild-type Ki-ras gene were assessed in terms of in vitro invasion, transformation, and VEGF production. Both mutants demonstrated equal abilities to transform Rat-1 cells and induce VEGF production, while cells transfected with wild-type Ki-Ras failed to do so. Most significantly, the valine-12 mutants demonstrated a greater ability to invade Matrigel than cells expressing the aspartate-12 mutant or wild-type Ki-Ras proteins. This study complements previous experimental data that specific Ras mutations differ in their effects in vivo and shows, for the first time, a significant difference in Matrigel invasion in vitro. The precise mechanisms behind these biological differences in vivo and in vitro should now be investigated.
Al-Mulla
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Kuwait University, Faculty of Medicine, Department of Pathology (Molecular Pathology Laboratory), P.O. Box 24923, Safat, Kuwait 13110. fahd@al-mulla.org
MacKenzie
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EM
D001224:Aspartic Acid / Q000235:genetics; D015153:Blotting, Western; D002471:Cell Transformation, Neoplastic / Q000235:genetics* / Q000473:pathology; D016228:Endothelial Growth Factors / Q000096:biosynthesis; D005347:Fibroblasts / Q000378:metabolism / Q000473:pathology; D006801:Humans; D008222:Lymphokines / Q000096:biosynthesis; D009154:Mutation; D009361:Neoplasm Invasiveness; D016283:Proto-Oncogene Proteins p21(ras) / Q000235:genetics*; D014162:Transfection; D014407:Tumor Cells, Cultured; D014633:Valine / Q000235:genetics; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
D016228:Endothelial Growth Factors; D008222:Lymphokines; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D001224:Aspartic Acid; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras); D014633:Valine