EXPRESSION AND TYROSINE PHOSPHORYLATION OF PHOSPHATIDYL-INOSITOL-3 KINASE IN HUMAN GASTRIC-CANCER CELLS - ITS CORRELATION WITH CELL-GROWTH

  • Authors:
    • HY XIAO
    • Y NAGAI
    • Y FUKUI
    • K TAMIYAKOIZUMI
    • H IWATA
    • T WATANABE
    • M HAMAGUCHI
  • View Affiliations

  • Published online on: February 1, 1995     https://doi.org/10.3892/ijo.6.2.405
  • Pages: 405-411
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Abstract

To reveal the signaling pathway leading to oncogenecity of human cancer cells, we examined the expression and tyrosine-phosphorylation of phosphatidylinositol (PI)-3 kinase in cancer cell lines. Of the 14 cell lines examined, two poorly differentiated human gastric cancer cell lines, NUGC-4 and MKN-45, which were previously found to have aberrant elevation of tyrosine phosphorylation showed elevated levels of PI-3 kinase 85-kDa subunit expression. In these cells, tyrosine-phosphorylation and overall activity of PI-3 kinase were apparently elevated, compared with normal human fibroblasts and another well differentiated gastric cancer cell line, MKN-28. Treatment of these cells with tyrosine kinase inhibitor, genistein, strongly suppressed the PI-3 kinase activity. Furthermore, wortmannin, a potent inhibitor of PI-3 kinase, strongly suppressed the growth of these gastric cancer cells. These results suggest that the growth signaling via tyrosine phosphorylation is required for the activation of PI-3 kinase in NUGC4 and MKN-45, and that this activation plays an important role in oncogenic growth of these cells. However, these two cell lines showed different responses of PI-3 kinase to acid-treatment and tyrosine kinase inhibitors. In MKN-45, activation of PI-3 kinase appeared to be constitutive, and could be relevant to the oncogenic nature of the cell line.

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February 1995
Volume 6 Issue 2

Print ISSN: 1019-6439
Online ISSN:1791-2423

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APA
XIAO, H., NAGAI, Y., FUKUI, Y., TAMIYAKOIZUMI, K., IWATA, H., WATANABE, T., & HAMAGUCHI, M. (1995). EXPRESSION AND TYROSINE PHOSPHORYLATION OF PHOSPHATIDYL-INOSITOL-3 KINASE IN HUMAN GASTRIC-CANCER CELLS - ITS CORRELATION WITH CELL-GROWTH. International Journal of Oncology, 6, 405-411. https://doi.org/10.3892/ijo.6.2.405
MLA
XIAO, H., NAGAI, Y., FUKUI, Y., TAMIYAKOIZUMI, K., IWATA, H., WATANABE, T., HAMAGUCHI, M."EXPRESSION AND TYROSINE PHOSPHORYLATION OF PHOSPHATIDYL-INOSITOL-3 KINASE IN HUMAN GASTRIC-CANCER CELLS - ITS CORRELATION WITH CELL-GROWTH". International Journal of Oncology 6.2 (1995): 405-411.
Chicago
XIAO, H., NAGAI, Y., FUKUI, Y., TAMIYAKOIZUMI, K., IWATA, H., WATANABE, T., HAMAGUCHI, M."EXPRESSION AND TYROSINE PHOSPHORYLATION OF PHOSPHATIDYL-INOSITOL-3 KINASE IN HUMAN GASTRIC-CANCER CELLS - ITS CORRELATION WITH CELL-GROWTH". International Journal of Oncology 6, no. 2 (1995): 405-411. https://doi.org/10.3892/ijo.6.2.405