Activated Ki-ras suppresses 12-O-tetradecanoylphorbol-13-acetate- induced activation of the c-Jun NH2-terminal kinase pathway in human colon cancer cells

Koji Okumura, Senji Shirasawa, Miharu Nishioka, Takehiko Sasazuki

Research output: Contribution to journalArticle

29 Citations (Scopus)

Abstract

Although the frequency of activated Ki-ras genes is high in human colorectal tumors, much less is known of activated Ki-ras-mediated signaling pathways. Using gene targeting, we examined HCT116 cells that contain the Gly-13→Asp mutation of Ki-ras and activated Ki-ras-disrupted clones derived from HCT116. 12-O-Tetradecanoylphorbol-13-acetate (TPA) induced immediate early genes, such as c-Jun, c-Fos, and Egr-1 in activated Ki-ras-disrupted clones, whereas c-Jun induction was rare in HCT116. TPA induced both phosphorylation of stress-activated protein kinase kinase 1 (SEK1) and c-Jun NH2-terminal kinase (JNK) in the activated Ki-ras-disrupted clones but not in HCT116. On the other hand, TPA-induced mitogen-activated protein kinase kinase 1/2 (MEK1/2)-extracellular signal-regulated kinase (ERK) activation was equally induced between HCT116 and the Ki-ras-disrupted clones. Furthermore, TPA-induced SEK1-JNK activation was observed in a DLD-1-derived activated Ki-ras-disrupted clone but not in DLD-1. The TPA-induced SEK1-JNK activation in these disrupted clones was completely inhibited by the protein kinase C (PKC) inhibitor, GF109203X (1 μM), but not by another PKC inhibitor, H7 (50 μM), whereas TPA-induced MEK1/2-ERK activation was partially and completely inhibited by GF109203X (1 μM) and H7 (50 μM), respectively. A phosphoinositol 3-kinase inhibitor, LY294002, did not inhibit the TPA-induced SEK1-JNK activation. Taken together, these results suggest that activated Ki-Ras-mediated signals are involved in the SEK1-JNK pathway through a PKC isotype that is distinct from that involved in MEK1/2-ERK activation in human colon cancer cells and independent of phosphoinositol 3- kinase activation, and the imbalance between ERK and JNK activity mused by activated Ki-Ras may play critical roles in human colorectal tumorigenesis.

Original languageEnglish
Pages (from-to)2445-2450
Number of pages6
JournalCancer Research
Volume59
Issue number10
Publication statusPublished - May 15 1999

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JNK Mitogen-Activated Protein Kinases
Tetradecanoylphorbol Acetate
Colonic Neoplasms
Clone Cells
MAP Kinase Kinase 2
Extracellular Signal-Regulated MAP Kinases
MAP Kinase Kinase 1
Protein Kinase C
Protein C Inhibitor
Protein Kinase Inhibitors
Phosphotransferases
MAP Kinase Kinase 4
HCT116 Cells
2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one
Immediate-Early Genes
ras Genes
Gene Targeting
Colorectal Neoplasms
Carcinogenesis
Phosphorylation

All Science Journal Classification (ASJC) codes

  • Oncology
  • Cancer Research

Cite this

Activated Ki-ras suppresses 12-O-tetradecanoylphorbol-13-acetate- induced activation of the c-Jun NH2-terminal kinase pathway in human colon cancer cells. / Okumura, Koji; Shirasawa, Senji; Nishioka, Miharu; Sasazuki, Takehiko.

In: Cancer Research, Vol. 59, No. 10, 15.05.1999, p. 2445-2450.

Research output: Contribution to journalArticle

Okumura, Koji ; Shirasawa, Senji ; Nishioka, Miharu ; Sasazuki, Takehiko. / Activated Ki-ras suppresses 12-O-tetradecanoylphorbol-13-acetate- induced activation of the c-Jun NH2-terminal kinase pathway in human colon cancer cells. In: Cancer Research. 1999 ; Vol. 59, No. 10. pp. 2445-2450.
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abstract = "Although the frequency of activated Ki-ras genes is high in human colorectal tumors, much less is known of activated Ki-ras-mediated signaling pathways. Using gene targeting, we examined HCT116 cells that contain the Gly-13→Asp mutation of Ki-ras and activated Ki-ras-disrupted clones derived from HCT116. 12-O-Tetradecanoylphorbol-13-acetate (TPA) induced immediate early genes, such as c-Jun, c-Fos, and Egr-1 in activated Ki-ras-disrupted clones, whereas c-Jun induction was rare in HCT116. TPA induced both phosphorylation of stress-activated protein kinase kinase 1 (SEK1) and c-Jun NH2-terminal kinase (JNK) in the activated Ki-ras-disrupted clones but not in HCT116. On the other hand, TPA-induced mitogen-activated protein kinase kinase 1/2 (MEK1/2)-extracellular signal-regulated kinase (ERK) activation was equally induced between HCT116 and the Ki-ras-disrupted clones. Furthermore, TPA-induced SEK1-JNK activation was observed in a DLD-1-derived activated Ki-ras-disrupted clone but not in DLD-1. The TPA-induced SEK1-JNK activation in these disrupted clones was completely inhibited by the protein kinase C (PKC) inhibitor, GF109203X (1 μM), but not by another PKC inhibitor, H7 (50 μM), whereas TPA-induced MEK1/2-ERK activation was partially and completely inhibited by GF109203X (1 μM) and H7 (50 μM), respectively. A phosphoinositol 3-kinase inhibitor, LY294002, did not inhibit the TPA-induced SEK1-JNK activation. Taken together, these results suggest that activated Ki-Ras-mediated signals are involved in the SEK1-JNK pathway through a PKC isotype that is distinct from that involved in MEK1/2-ERK activation in human colon cancer cells and independent of phosphoinositol 3- kinase activation, and the imbalance between ERK and JNK activity mused by activated Ki-Ras may play critical roles in human colorectal tumorigenesis.",
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