Correlation of MAP kinases with COX‐2 induction differs between MKN45 and HT29 cells

• Published in: Alimentary pharmacology & therapeutics 2004-07, Vol.20 (s1), p.143-150
• Main Authors: Tominaga, K., Higuchi, K., Sasaki, E., Suto, R., Watanabe, T., Fujiwara, Y., Oshitani, N., Matsumoto, T., Kim, S., Iwao, H., Arakawa, T.
• Format: Article
• Language: English
• Subjects: Blotting, Western; Cell Division; Cell Line, Tumor; Colonic Neoplasms - enzymology; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Cyclooxygenase Inhibitors - pharmacology; Enzyme Inhibitors - pharmacology; Flavonoids - pharmacology; HT29 Cells; Humans; Imidazoles - pharmacology; Isoenzymes - antagonists & inhibitors; Isoenzymes - metabolism; Membrane Proteins; Mitogen-Activated Protein Kinase Kinases - metabolism; Prostaglandin-Endoperoxide Synthases - metabolism; Pyridines - pharmacology; Serum - physiology; Stomach Neoplasms - enzymology
• ISSN: 0269-2813; 1365-2036
• DOI: 10.1111/j.1365-2036.2004.01986.x

Summary Background : Mitogen‐activated protein (MAP) kinases, including extracellular signal‐regulated kinases (ERK),c‐Jun NH2‐terminal kinases (JNK) and p38 MAP kinase (p38 MAPK) are important intermediates of the signal‐transduction pathway from the cell surface to the nucleus. Expression of cyclooxygenase (COX)‐2, associated with proliferation, apoptosis or both of gastrointestinal cancer cells, is mediated through MAP kinase families. However, the correlation between respective MAP kinase signals and COX‐2 in the proliferation of gastric and colon cancer cells has not been well elucidated. Aim : We examined the effect of selective inhibitors of MAP kinases and COX‐2 on serum‐induced proliferation of gastric (MKN45) and colon (HT29) cancer cells. Methods : After 24‐h serum starvation, cancer cells were stimulated with 2% serum and COX‐2 inhibitors (NS398 10 µmol/L, or etodolac 100 µmol/L) or 1 h after preincubation with inhibitors for ERK (PD98059 20 µmol/L) or p38 MAPK (SB203580 10 µmol/L). Phosphorylated MAP kinases and COX‐2 protein were evaluated by Western blotting, and the proliferation of cancer cells was estimated by 3H‐thymidine incorporation. Transcription factors nuclear factor‐κB and CREB were assayed by an electorophoretic mobility shift assay. Results : Serum increased the proliferation of MKN45 and HT29 cells by 280% and 200%, respectively, compared with the control levels (100%). In both cancer cells, phosphorylated MAP kinases were increased within 30 min after stimulation. PD98059 and SB203580 inhibited the serum‐induced proliferation of MKN45 by 21% and 51% and of HT29 by 81% and 69%, respectively. NS398 and etodolac inhibited the proliferation of HT29 by 21% and 41%, respectively, but not that of MKN45. PD98059 and SB203580 also suppressed serum‐induced expression of COX‐2 protein in HT29 cells. In addition to the activation of MAP kinases and COX‐2, activities of nuclear factor‐κB and CREB were also increased during HT29 cell proliferation. Conclusions : These results suggest that the correlation of MAP kinases with COX‐2 induction for cell proliferation differs between MKN45 and HT29 cells.