Mechanisms of endothelin 1-stimulated proliferation in colorectal cancer cell lines.
BACKGROUND
The peptide endothelin (ET) 1 promotes proliferation in a number of epithelial cancers. The aim of this study was to identify the mechanism of ET-1-stimulated proliferation in colorectal cancer cells in vitro.


METHODS
The effects of ET-1 on colorectal cancer cell lines HT29, LIM1215 and SW620 were studied. Cells were cultured with ET-1 plus antagonists/inhibitors to ET(A) or ET(B) receptors, G protein subtypes, phosphoinositide 3-kinase (PI3K) or protein kinase C (PKC). DNA replication and apoptosis were investigated by 5-bromo-2'-deoxyuridine incorporation and Annexin V staining. Transactivation of the epidermal growth factor (EGF) receptor was investigated by blockade of the receptor in the presence of ET-1, measurement of levels of phosphorylated EGF receptor in the presence of ET-1, and comparing the effects of ET-1 and EGF on cell proliferation.


RESULTS
ET-1 significantly stimulated growth of all cell lines via ET(A) receptors. ET-1 stimulated DNA replication, not apoptosis. ET-1-stimulated growth was inhibited by antagonism of pertussis toxin-sensitive G proteins, PI3K and PKC. Inhibition of the EGF receptor reduced the effect of ET-1. ET-1 increased levels of phosphorylated EGF receptor via the ET(A) receptor.


CONCLUSIONS
ET-1 increased DNA replication in colorectal cancer cells via the ET(A) receptor. This mitogenic action was mediated via pertussis toxin-sensitive G proteins, PI3K, PKC and transactivation of the EGF receptor.
Grant
K
K
Department of Surgery, Royal Free and University College Medical School, University College London, London, UK.
Knowles
J
J
Dawas
K
K
Burnstock
G
G
Taylor
I
I
Loizidou
M
M
D000704:Analysis of Variance; D049109:Cell Proliferation / Q000187:drug effects; D015179:Colorectal Neoplasms / Q000378:metabolism / Q000473:pathology*; D004273:DNA, Neoplasm / Q000187:drug effects / Q000378:metabolism; D065128:Endothelin Receptor Antagonists; D019332:Endothelin-1 / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D066246:ErbB Receptors / Q000378:metabolism*; D005434:Flow Cytometry; D006801:Humans; D007150:Immunohistochemistry; D014407:Tumor Cells, Cultured
D004273:DNA, Neoplasm; D065128:Endothelin Receptor Antagonists; D019332:Endothelin-1; D066246:ErbB Receptors