STAT3, but not ERKs, mediates the IL-6-induced proliferation of renal cancer cells, ACHN and 769P

Akio Horiguchi, Mototsugu Oya, Ken Marumo, Masaru Murai

Research output: Contribution to journalArticle

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Abstract

Background. Although interleukin-6 (IL-6) has been suggested to function as an autocrine growth factor in renal cell carcinoma (RCC), the underlying mechanism responsible for the IL-6-induced proliferation of RCC has not been defined. The aim of this study was to characterize the signaling cascades mediating IL-6-induced proliferation and to investigate the use of effective novel interventions to block the IL-6-induced autocrine growth of renal cancer cells. Methods. IL-6-induced proliferation and intracellular signaling cascades were analyzed in four human renal cancer cell lines Caki-1, ACHN, 769P and A498. IL-6-induced activation of STAT3 (signal transducer and activator of transcription-1) and extracellular signal-regulated kinases (ERKs), and the effects of anti-IL-6 neutralizing antibody, Jak inhibitor AG 490, and MEK1 inhibitor PD 98059 were analyzed by Western blotting using phospho-specific antibodies. The DNA-binding activities of STATs were analyzed by EMSA. Apoptosis was determined by using nuclear staining and the TUNEL assay. Changes in the apoptosis-related proteins, bcl-2, bcl-xL, and bax were analyzed by Western blotting. Results. IL-6 induced tyrosine phosphorylation and increased the DNA binding activity of STAT3 and, to a lesser extent, STAT1 in all cell lines except for Caki-1, which did not express the IL-6 receptor subunit gp130. ERKs were constitutively activated in all cell lines and the activation level was not up-regulated further by exogenously added IL-6 nor down-regulated by anti-IL-6 neutralizing antibody. IL-6-induced STAT3 tyrosine phosphorylation and DNA binding activity was inhibited by treatment with Jak specific inhibitor AG 490; however, it was not affected by the MEK1 inhibitor PD 98059. Moreover, treatment with AG 490 inhibited IL-6-induced proliferation of ACHN and 769P cells and induced apoptosis with the down-regulation of bcl-2 and the up-regulation of bax. Conclusions. This study identified STAT3, but not ERKs, to be a major mediator of IL-6-induced proliferation of renal cancer cells. Although ERKs were constitutively activated, ERKs were not found to be essential for the IL-6-induced proliferation and modulation of the STAT3 activity. Because the Jak specific inhibitor AG 490 effectively inhibited the IL-6-induced STAT3 activity and induced apoptosis, the blockade of the STAT3 signaling pathways is considered to be potentially useful as a novel therapeutic approach for RCC.

Original languageEnglish
Pages (from-to)926-938
Number of pages13
JournalKidney International
Volume61
Issue number3
DOIs
Publication statusPublished - 2002

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Extracellular Signal-Regulated MAP Kinases
Renal Cell Carcinoma
Interleukin-6
Apoptosis
Neutralizing Antibodies
Cell Line
Tyrosine
DNA
Western Blotting
Phosphorylation
Phospho-Specific Antibodies
STAT1 Transcription Factor
Interleukin-6 Receptors
Kidney Neoplasms
In Situ Nick-End Labeling
Intercellular Signaling Peptides and Proteins

Keywords

  • Apoptosis
  • Cell proliferation
  • Extracellular signal-regulated kinases
  • Intracellular signaling
  • Kidney cancer
  • Renal cell carcinoma
  • STAT3

ASJC Scopus subject areas

  • Nephrology

Cite this

STAT3, but not ERKs, mediates the IL-6-induced proliferation of renal cancer cells, ACHN and 769P. / Horiguchi, Akio; Oya, Mototsugu; Marumo, Ken; Murai, Masaru.

In: Kidney International, Vol. 61, No. 3, 2002, p. 926-938.

Research output: Contribution to journalArticle

Horiguchi, Akio ; Oya, Mototsugu ; Marumo, Ken ; Murai, Masaru. / STAT3, but not ERKs, mediates the IL-6-induced proliferation of renal cancer cells, ACHN and 769P. In: Kidney International. 2002 ; Vol. 61, No. 3. pp. 926-938.
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abstract = "Background. Although interleukin-6 (IL-6) has been suggested to function as an autocrine growth factor in renal cell carcinoma (RCC), the underlying mechanism responsible for the IL-6-induced proliferation of RCC has not been defined. The aim of this study was to characterize the signaling cascades mediating IL-6-induced proliferation and to investigate the use of effective novel interventions to block the IL-6-induced autocrine growth of renal cancer cells. Methods. IL-6-induced proliferation and intracellular signaling cascades were analyzed in four human renal cancer cell lines Caki-1, ACHN, 769P and A498. IL-6-induced activation of STAT3 (signal transducer and activator of transcription-1) and extracellular signal-regulated kinases (ERKs), and the effects of anti-IL-6 neutralizing antibody, Jak inhibitor AG 490, and MEK1 inhibitor PD 98059 were analyzed by Western blotting using phospho-specific antibodies. The DNA-binding activities of STATs were analyzed by EMSA. Apoptosis was determined by using nuclear staining and the TUNEL assay. Changes in the apoptosis-related proteins, bcl-2, bcl-xL, and bax were analyzed by Western blotting. Results. IL-6 induced tyrosine phosphorylation and increased the DNA binding activity of STAT3 and, to a lesser extent, STAT1 in all cell lines except for Caki-1, which did not express the IL-6 receptor subunit gp130. ERKs were constitutively activated in all cell lines and the activation level was not up-regulated further by exogenously added IL-6 nor down-regulated by anti-IL-6 neutralizing antibody. IL-6-induced STAT3 tyrosine phosphorylation and DNA binding activity was inhibited by treatment with Jak specific inhibitor AG 490; however, it was not affected by the MEK1 inhibitor PD 98059. Moreover, treatment with AG 490 inhibited IL-6-induced proliferation of ACHN and 769P cells and induced apoptosis with the down-regulation of bcl-2 and the up-regulation of bax. Conclusions. This study identified STAT3, but not ERKs, to be a major mediator of IL-6-induced proliferation of renal cancer cells. Although ERKs were constitutively activated, ERKs were not found to be essential for the IL-6-induced proliferation and modulation of the STAT3 activity. Because the Jak specific inhibitor AG 490 effectively inhibited the IL-6-induced STAT3 activity and induced apoptosis, the blockade of the STAT3 signaling pathways is considered to be potentially useful as a novel therapeutic approach for RCC.",
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T1 - STAT3, but not ERKs, mediates the IL-6-induced proliferation of renal cancer cells, ACHN and 769P

AU - Horiguchi, Akio

AU - Oya, Mototsugu

AU - Marumo, Ken

AU - Murai, Masaru

PY - 2002

Y1 - 2002

N2 - Background. Although interleukin-6 (IL-6) has been suggested to function as an autocrine growth factor in renal cell carcinoma (RCC), the underlying mechanism responsible for the IL-6-induced proliferation of RCC has not been defined. The aim of this study was to characterize the signaling cascades mediating IL-6-induced proliferation and to investigate the use of effective novel interventions to block the IL-6-induced autocrine growth of renal cancer cells. Methods. IL-6-induced proliferation and intracellular signaling cascades were analyzed in four human renal cancer cell lines Caki-1, ACHN, 769P and A498. IL-6-induced activation of STAT3 (signal transducer and activator of transcription-1) and extracellular signal-regulated kinases (ERKs), and the effects of anti-IL-6 neutralizing antibody, Jak inhibitor AG 490, and MEK1 inhibitor PD 98059 were analyzed by Western blotting using phospho-specific antibodies. The DNA-binding activities of STATs were analyzed by EMSA. Apoptosis was determined by using nuclear staining and the TUNEL assay. Changes in the apoptosis-related proteins, bcl-2, bcl-xL, and bax were analyzed by Western blotting. Results. IL-6 induced tyrosine phosphorylation and increased the DNA binding activity of STAT3 and, to a lesser extent, STAT1 in all cell lines except for Caki-1, which did not express the IL-6 receptor subunit gp130. ERKs were constitutively activated in all cell lines and the activation level was not up-regulated further by exogenously added IL-6 nor down-regulated by anti-IL-6 neutralizing antibody. IL-6-induced STAT3 tyrosine phosphorylation and DNA binding activity was inhibited by treatment with Jak specific inhibitor AG 490; however, it was not affected by the MEK1 inhibitor PD 98059. Moreover, treatment with AG 490 inhibited IL-6-induced proliferation of ACHN and 769P cells and induced apoptosis with the down-regulation of bcl-2 and the up-regulation of bax. Conclusions. This study identified STAT3, but not ERKs, to be a major mediator of IL-6-induced proliferation of renal cancer cells. Although ERKs were constitutively activated, ERKs were not found to be essential for the IL-6-induced proliferation and modulation of the STAT3 activity. Because the Jak specific inhibitor AG 490 effectively inhibited the IL-6-induced STAT3 activity and induced apoptosis, the blockade of the STAT3 signaling pathways is considered to be potentially useful as a novel therapeutic approach for RCC.

AB - Background. Although interleukin-6 (IL-6) has been suggested to function as an autocrine growth factor in renal cell carcinoma (RCC), the underlying mechanism responsible for the IL-6-induced proliferation of RCC has not been defined. The aim of this study was to characterize the signaling cascades mediating IL-6-induced proliferation and to investigate the use of effective novel interventions to block the IL-6-induced autocrine growth of renal cancer cells. Methods. IL-6-induced proliferation and intracellular signaling cascades were analyzed in four human renal cancer cell lines Caki-1, ACHN, 769P and A498. IL-6-induced activation of STAT3 (signal transducer and activator of transcription-1) and extracellular signal-regulated kinases (ERKs), and the effects of anti-IL-6 neutralizing antibody, Jak inhibitor AG 490, and MEK1 inhibitor PD 98059 were analyzed by Western blotting using phospho-specific antibodies. The DNA-binding activities of STATs were analyzed by EMSA. Apoptosis was determined by using nuclear staining and the TUNEL assay. Changes in the apoptosis-related proteins, bcl-2, bcl-xL, and bax were analyzed by Western blotting. Results. IL-6 induced tyrosine phosphorylation and increased the DNA binding activity of STAT3 and, to a lesser extent, STAT1 in all cell lines except for Caki-1, which did not express the IL-6 receptor subunit gp130. ERKs were constitutively activated in all cell lines and the activation level was not up-regulated further by exogenously added IL-6 nor down-regulated by anti-IL-6 neutralizing antibody. IL-6-induced STAT3 tyrosine phosphorylation and DNA binding activity was inhibited by treatment with Jak specific inhibitor AG 490; however, it was not affected by the MEK1 inhibitor PD 98059. Moreover, treatment with AG 490 inhibited IL-6-induced proliferation of ACHN and 769P cells and induced apoptosis with the down-regulation of bcl-2 and the up-regulation of bax. Conclusions. This study identified STAT3, but not ERKs, to be a major mediator of IL-6-induced proliferation of renal cancer cells. Although ERKs were constitutively activated, ERKs were not found to be essential for the IL-6-induced proliferation and modulation of the STAT3 activity. Because the Jak specific inhibitor AG 490 effectively inhibited the IL-6-induced STAT3 activity and induced apoptosis, the blockade of the STAT3 signaling pathways is considered to be potentially useful as a novel therapeutic approach for RCC.

KW - Apoptosis

KW - Cell proliferation

KW - Extracellular signal-regulated kinases

KW - Intracellular signaling

KW - Kidney cancer

KW - Renal cell carcinoma

KW - STAT3

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