Heparin regulates colon cancer cell growth through p38 mitogen-activated protein kinase signalling.
OBJECTIVE
Heparin acts as an extracellular stimulus capable of activating major cell signalling pathways. Thus, we examined the putative mechanisms utilized by heparin to stimulate HT29, SW1116 and HCT116 colon cancer cell growth.


METHODS
Possible participation of the mitogen-activated protein kinase (MAPK) cascade on heparin-induced HT29, SW1116 and HCT116 colon cancer cell growth was evaluated using specific MAPK cascade inhibitors, Western blot analysis, real-time quantitative PCR and FACS apoptosis analysis.


RESULTS
Treatment with a highly specific p38 kinase inhibitor, SB203580, significantly (50-70%) inhibited heparin-induced colon cancer cell growth, demonstrating that p38 MAPK signalling is involved in their heparin-induced proliferative response. This was shown to be correlated with increased (up to 3-fold) phosphorylation of 181/182 threonine/tyrosine residues on p38 MAP kinase. Furthermore, heparin inhibited cyclin-dependent kinase inhibitor p21(WAF1/CIP1) and p53 tumour suppressor gene and protein expression up to 2-fold or 1.8-fold, respectively, and stimulated cyclin D1 expression up to 1.8-fold, in these cell lines through a p38-mediated mechanism. On the other hand, treatment with heparin did not appear to affect HT29, SW1116 and HCT116 cell levels of apoptosis.


CONCLUSIONS
This study demonstrates that an extracellular glycosaminoglycan, heparin, finely modulates expression of genes crucial to cell cycle regulation through specific activation of p38 MAP kinase to stimulate colon cancer cell growth.
Department of Histology, Division of Morphology, School of Medicine, University of Crete, Heraklion, Greece.
G
G
Chatzinikolaou
D
D
Nikitovic
A
A
Berdiaki
A
A
Zafiropoulos
P
P
Katonis
N K
NK
Karamanos
G N
GN
Tzanakakis
D017209:Apoptosis; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000201:enzymology*; D019938:Cyclin D1; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000235:genetics / Q000378:metabolism; D005434:Flow Cytometry; D045325:HCT116 Cells; D006493:Heparin / Q000494:pharmacology*; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D020935:MAP Kinase Signaling System; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
D050759:Cyclin-Dependent Kinase Inhibitor p21; D007093:Imidazoles; D047428:Protein Kinase Inhibitors; D011725:Pyridines; D016159:Tumor Suppressor Protein p53; D019938:Cyclin D1; D006493:Heparin; D048051:p38 Mitogen-Activated Protein Kinases; C093642:SB 203580