title: p38 kinase is a key signaling molecule for H-Ras-induced cell motility and invasive phenotype in human breast epithelial cells.
abstract: Ras expression has been suggested as a marker for tumor aggressiveness of breast cancer,including the degrees of invasion and tumor recurrence.We showed previously that H-ras, but not N-ras, up-regulates matrix metalloproteinase 2 expression and induces invasive phenotype in MCF10A human breast epithelial cells (A. Moon, et al. Int. J. Cancer, 85: 176-181, 2000). In this study, we show that H-ras also promotes cell motility more effectively than N-ras in MCF10A cells. We have investigated H-ras-specific signaling pathway(s) critical for H-ras-mediated cell motility and invasive phenotype. Whereas neither H-ras nor N-ras activated c-Jun NH(2)-terminal kinase 1, both H-ras and N-ras effectively activated extracellular signal-regulated protein kinase (ERK) -1,2. Importantly, prominent activation of p38 mitogen-activated protein kinase was shown only in H-ras-activated cells but not in N-ras-activated MCF10A cells. Functional significance of H-ras-activated p38 in invasiveness and cell motility was evidenced by studies using SB203580, a chemical inhibitor of p38, and a dominant-negative construct of p38. Whereas inhibition of c-Jun NH(2)-terminal kinase 1 activity had no effect on H-ras-induced MCF10A cell invasion and motility, the inhibition of the ERK pathway using a chemical inhibitor PD98059 or dominant-negative mutant of mitogen-activated protein/ERK kinase 1, an activator of ERKs, significantly reduced H-ras-induced invasion and migration. We also provide evidence that p38 and, to a lesser degree, ERKs, are critical for H-ras-mediated up-regulation of matrix metalloproteinase 2. Taken together, the present study shows that H-ras activation of both p38 and ERKs induces cell invasion and motility, whereas N-ras activation of ERKs alone is not sufficient. This study reveals the p38 kinase as a key signaling molecule differentially regulated by H-ras and N-ras, leading to H-ras-specific cell invasive and migrative phenotypes in human breast epithelial cells.
mesh_terms: D001940:Breast / Q000166:cytology* / Q000201:enzymology*; D001943:Breast Neoplasms / Q000201:enzymology / Q000473:pathology; D002465:Cell Movement / Q000502:physiology*; D004789:Enzyme Activation; D006801:Humans; D020935:MAP Kinase Signaling System / Q000502:physiology*; D020778:Matrix Metalloproteinase 2 / Q000096:biosynthesis / Q000235:genetics; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048055:Mitogen-Activated Protein Kinase 8; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism / Q000502:physiology*; D009361:Neoplasm Invasiveness; D015854:Up-Regulation; D048051:p38 Mitogen-Activated Protein Kinases; D018631:ras Proteins / Q000502:physiology*
chemical_list: D019950:Mitogen-Activated Protein Kinase 1; D048055:Mitogen-Activated Protein Kinase 8; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D020778:Matrix Metalloproteinase 2; D018631:ras Proteins