An effect of K-ras gene mutation on epidermal growth factor receptor signal transduction in PANC-1 pancreatic carcinoma cells.
The Ras protein is involved in tyrosine kinase signal transduction pathway steps such as EGFR signalling. Most human pancreatic carcinomas harbor a point mutation of K-ras oncogene and overexpress transforming TGF-alpha. We studied how K-ras gene mutation could influence the EGFR signal transduction mechanism and the autonomous proliferation of pancreatic carcinoma cells, using PANC-1 human pancreatic carcinoma line and W1-38 normal human fibroblast cell line as a control. PANC-1 cells responded to neither EGF nor exogenous TGF-alpha, although anti-TGF-alpha MAb suppressed their growth. Expression of TGF-alpha mRNA was detected only in PANC-1 cells, which confirmed EGFR being within an autocrine loop. Ras protein and MAP kinase were constitutively activated in PANC-1 cells so that the cells did not respond to treatment with staurosporine or herbimycin A, and exhibited slight response to EGF stimulation. PANC-1 cells harbored K-ras gene mutation in codon 12. In contrast, EGF stimulation induced an elevation of GTP-bound ratio to Ras protein and an activation of MAP kinase with accelerated growth in W1-38 cells. From these findings, we concluded that K-ras gene mutation possibly plays an important role in the autonomous proliferation of PANC-1 pancreatic carcinoma cells, and that an autocrine loop represented by TGF-alpha and EGFR may further accelerate the growth of PANC-1 cells.
Watanabe
M
M
Third Department of Internal Medicine, Hokkaido University School of Medicine, Sapporo, Japan.
Nobuta
A
A
Tanaka
J
J
Asaka
M
M
D000911:Antibodies, Monoclonal / Q000494:pharmacology; D001483:Base Sequence; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004815:Epidermal Growth Factor / Q000494:pharmacology; D066246:ErbB Receptors / Q000378:metabolism*; D011905:Genes, ras / Q000235:genetics*; D006150:Guanine Nucleotides / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D010190:Pancreatic Neoplasms / Q000235:genetics*; D019000:Phosphotyrosine / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics*; D016211:Transforming Growth Factor alpha / Q000235:genetics / Q000276:immunology / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D018631:ras Proteins / Q000378:metabolism
D000911:Antibodies, Monoclonal; D004791:Enzyme Inhibitors; D006150:Guanine Nucleotides; D012333:RNA, Messenger; D016211:Transforming Growth Factor alpha; D019000:Phosphotyrosine; D004815:Epidermal Growth Factor; D066246:ErbB Receptors; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D018631:ras Proteins