Specific inhibitor of MEK-mediated cross-talk between ERK and p38 MAPK during differentiation of human osteosarcoma cellsReport as inadecuate




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Journal of Cell Communication and Signaling

, Volume 1, Issue 2, pp 103–111

First Online: 04 October 2007Received: 10 May 2007Accepted: 07 August 2007DOI: 10.1007-s12079-007-0010-2

Cite this article as: Shimo, T., Matsumura, S., Ibaragi, S. et al. J. Cell Commun. Signal. 2007 1: 103. doi:10.1007-s12079-007-0010-2

Abstract

Osteosarcoma is the most common primary malignant bone tumor, accounting for approximately 20% of all primary sarcomas in bone. Although treatment modalities have been improved over the past decades, it is still a tumor with a high mortality rate in children and young adults. Based on histological considerations, osteosarcoma arises from impaired differentiation of these immature cells into more mature types and that correction of this impairment may reduce malignancy and increase the efficiency of chemotherapy. The purpose of this study was to determine the effect of specific inhibitors of MAPK extracellular signaling-regulated kinase ERK kinase MEK and p38 on the differentiation of human osteosarcoma cell line SaOS-2 cells. We found that PD98059, a specific inhibitor of MEK, inhibited the serum-stimulated proliferation of SaOS-2 cells; whereas SB203580, a specific inhibitor of p38 MAPK, had little effect on it. SB203580 suppressed ALPase activity, gene expression of type I collagen, and expression of ALP and BMP-2 mRNAs; whereas PD98059 upregulated them dose dependently. In addition, immunoblot and immunostaining analysis revealed that phosphorylation of ERK was increased by treatment with SB203580; whereas PD98059 increased the phosphorylation of p38, which implies a seesaw-like balance between ERK and p38 phosphorylation. We suggest that osteosarcoma cell differentiation is regulated by the balance between the activities of the ERK and p38 pathways and that the MEK-ERK pathway negatively regulates osteosarcoma cell differentiation, whereas the p38 pathway does so positively. MEK inhibitor may thus be a good candidate for altering the expression of the osteosarcoma malignant phenotype.

Keywords Mitogen-activated protein kinase Extracellular signal-regulated kinase Differentiaton  Download fulltext PDF



Author: Tsuyoshi Shimo - Shinsuke Matsumura - Soichiro Ibaragi - Sachiko Isowa - Koji Kishimoto - Hiroshi Mese - Akiyoshi Nishiyama

Source: https://link.springer.com/







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