Constitutive activation of Stat3 by the Src and JAK tyrosine kinases participates in growth regulation of human breast carcinoma cells

Garcia, Roy; Bowman, Tammy; Niu, Guilian; Yu, Hua; Minton, Sue; Muro-Cacho, Carlos; Cox, Charles E.; Falcone, Robert E.; Fairclough, Rita; Parsons, Sarah J.; Laudano, Andy; Gazit, Aviv; Levitzki, Alexander; Kraker, Alan J.; Jove, Richard

doi:10.1038/sj.onc.1204349

Cited by 667 publications

(620 citation statements)

References 72 publications

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“…We also observed a basal tyrosine kinase activity in immunoprecipitates of c-Src from hepatocyte lysates, which was inhibited by CGP77675, but so far we have not found any significant increase of this kinase activity after EGF stimulation (data not shown). The data support the notion that although c-Src tyrosine kinase activity is required for EGF-induced Stat5b activation, this might reflect a cooperation between cSrc and the EGF receptor and not necessarily c-Src activation as a direct downstream effect of the EGF receptor (Biscardi et al, 1999;Abram and Courtneidge, 2000;Reddy et al, 2000;Garcia et al, 2001).…”

Section: Discussionsupporting

confidence: 82%

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EGF receptor‐mediated, c‐Src‐dependent, activation of Stat5b is downregulated in mitogenically responsive hepatocytes

Guren

Ødegård

Abrahamsen

et al. 2003

Journal Cellular Physiology

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Signal transducer and activator of transcription (STAT) proteins may be activated by epidermal growth factor (EGF), but their role in EGF receptor-mediated mitogenic signaling is not clear. We previously showed that Stat5b was activated by EGF in rat hepatocytes in primary monolayer culture. In the present study, we found that EGF induced tyrosine phosphorylation of Stat5b both on Tyr-699, which correlated with specific DNA binding activity, and also on other tyrosine residues. The Src tyrosine kinase inhibitor CGP77675 blocked the EGF-induced activation of Stat5b, but did not affect the Stat5b activation by growth hormone (GH) or prolactin (PRL). The Stat5b response to EGF was most pronounced soon (3 h) after plating (early G 1 ) and at high cell density (50,000 hepatocytes per cm 2 ). However, at this cell density EGF did not stimulate DNA synthesis. In hepatocytes at 24 h of culturing (mid/late G 1 ) with 20,000 cells per cm 2 , EGF induced strong phosphorylation of the EGF receptor, as well as Shc and ERK, and stimulated DNA synthesis, but did not activate Stat5b, although the Stat5b response to GH or PRL was retained. A strong GHinduced Stat5b activation neither influenced the DNA synthesis alone nor enhanced the mitogenic effect of EGF. The results show that EGF induces tyrosine phosphorylation and DNA-binding activity of Stat5b in a manner different from GH and PRL, apparently by a Src-dependent mechanism. The data also provide further evidence that Stat5b is not required for mitogenic signaling from the EGF receptor.

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Section: Discussionsupporting

confidence: 82%

“…There are data suggesting that STAT proteins may have a role in cellular actions of Src (Bromberg et al, 1998b;Turkson et al, 1998;Garcia et al, 2001). The present results with the inhibitor CGP77675, suggested that c-Scr tyrosine kinase is selectively involved in the EGF-induced activation of Stat5b in hepatocytes.…”

Section: Discussionmentioning

confidence: 99%

EGF receptor‐mediated, c‐Src‐dependent, activation of Stat5b is downregulated in mitogenically responsive hepatocytes

Guren

Ødegård

Abrahamsen

et al. 2003

Journal Cellular Physiology

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“…Although Stat3 (S727) remains correlate well with kinases in this cascade including EGFR, PDK-1, AKT, mTOR, p70S6K and S6 (Po0.05 in Table 1), phosphorylated Stat3 (Y705) did not correlate with PDK-1 phosphorylation in this study (P40.05; Table 2), despite it is associated with invasive breast carcinoma (Po0.05; Table 2). It hence suggests that Stat3 phosphorylation (Y705) was likely accomplished by different kinase(s) that were excluded from PDK-1/mTOR/p70S6K/S6K pathway and further support the notion indicating phosphorylation on these two residues was mediated by independent signalling events (Jain et al, 1999;Yokogami et al, 2000;Garcia et al, 2001;Lim and Cao, 2001;Yonezawa et al, 2004).…”

Section: Concomitant Phosphorylation Of Pdk-1 With Other Downstream Ksupporting

confidence: 68%

“…Numerous studies suggested constitutively activated Stat3 plays an oncogenic role in many types in human cancers including breast cancer (Bowman et al, 2000;Garcia et al, 2001). Activation of Stat3 requires phosphorylation on two residues S727 and Y705 (Wen et al, 1995;Jain et al, 1999;Lim and Cao, 2001).…”

Section: Phosphorylation Of Stat3 In Breast Cancermentioning

confidence: 99%

Elevated phosphorylation and activation of PDK-1/AKT pathway in human breast cancer

et al. 2005

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Activation of kinases signalling pathways contributes to various malignant phenotypes in human cancers, including breast tumour. To examine the possible activation of these signalling molecules, we examined the phosphorylation status in 12 protein kinases and transcription factors in normal primary human mammary epithelial cells, telomerase-immortalised human breast epithelial cell line, and two breast cancer lines, MDA-MB-468 and MCF-7, using Kinexus phosphorylated protein screening assays. The phosphorylation of FAK, mTOR, p70S6K, and PDK-1 were elevated in both breast cancer cell lines, whereas the phosphorylation of AKT, EGFR, ErbB2/ Her2, PDGFR, Shc, and Stat3 were elevated in only one breast cancer line compared to normal primary mammary epithelial cells and telomerase-immortalised breast epithelial cells. The same findings were confirmed by Western blotting and by kinase assays. We further substantiated the phosphorylation status of these molecules in tissue microarray slides containing 89 invasive breast cancer tissues as well as six normal mammary tissues with immunohistochemistry staining using phospho-specific antibodies. Consistent findings were obtained as greater than 70% of invasive breast carcinomas expressed moderate to high levels of phosphorylated PDK-1, AKT, p70S6K, and EGFR. In sharp contrast, phosphorylation of the same proteins was nearly undetectable or was at low levels in normal mammary tissues under the same assay. Elevated phosphorylation of PDK-1, AKT, mTOR, p70S6K, S6, EGFR, and Stat3 were highly associated with invasive breast tumours (Po0.05). Taken together, our results suggest that activation of these kinase pathways by phosphorylation may in part account for molecular pathogenesis of human breast carcinoma. Particularly, moderate to high level of PDK-1 phosphorylation was found in 86% of high-grade metastasised breast tumours. This is the first report demonstrating phosphorylation of PDK-1 is frequently elevated in breast cancer with concomitantly increased phosphorylation of downstream kinases, including AKT, mTOR, p70S6K, S6, and Stat3. This finding thus suggested PDK-1 may promote oncogenesis in part through the activation of AKT and p70S6K and rationalised that PDK-1 as well as downstream components of PDK-1 signalling pathway may be promising therapeutic targets to treat breast cancer. Breast cancer remains to be a major cause of death in women worldwide, despite improvements in cancer prevention, early detection, treatment, and understanding the molecular pathogenesis. It hence demands an urgent need to unveil the exact mechanism of oncogenesis and tumour progression, which may prelude the development of new strategies for treatment. Breast carcinoma emerges through multistep processes progressing from hyperplasia to premalignant change, in situ carcinoma, invasion, and distal metastasis, in concomitant with gain of oncogenic activities and loss of tumour suppressor gene functions.Protein kinases have been implicated in playing crucial roles in regulating cell growth, met...

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“…To this end, we used the transitional bladder cancer cell line T24 in which EGFR is expressed (Dominguez-Escrig et al, 2004). EGFR, in response to its ligands, phosphorylates STAT proteins directly or indirectly through nonreceptor-type tyrosine kinases (Garcia et al, 2001). Our Western blot assay revealed the expression of STAT1a, 1b, 3 and 5 in T24 cells.…”

Section: Discussionmentioning

confidence: 99%

Requirement of STAT3 activation for maximal collagenase-1 (MMP-1) induction by epidermal growth factor and malignant characteristics in T24 bladder cancer cells

et al. 2005

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Signal transducers and activators of transcription (STATs) are latent transcription factors that mediate cytokine-and growth factor-induced transcription. Constitutive activation of STAT3 has been shown in human cancers and transformed cell lines. We report that STAT3, but not STAT1 and STAT5, becomes phosphorylated in response to epidermal growth factor (EGF) and achieves maximal induction of collagenase-1 (MMP-1) transcription by interacting with c-JUN. Phosphorylation of STAT3 protein is biphasic: the first peak within 30 min and the second peak between 4 and 8 h. Association of STAT3 with c-JUN is detected and its constituting STAT3 is increasingly phosphorylated. The STAT and AP-1 elements are necessary for effective induction of MMP-1 promoter by EGF. Mutation of AP-1 element closely located at the STAT site abolishes the binding not only of c-JUN but also of STAT3 to MMP-1 promoter, resulting in the loss of the responsiveness to EGF. By blocking STAT3 activity with the dominant-negative form, we show the requirement of STAT3 for EGF induction of MMP-1 and MMP-10 (stromelysin-2). Furthermore, expression of the dominant-negative STAT3 is sufficient to inhibit the constitutive and EGF-inducible cell migration and invasion and the tumor formation in nude mice. These results demonstrate that STAT3 phosphorylation and its possible interaction with c-JUN are required for the strong responsiveness of MMP-1 to EGF, and STAT3 activation is crucial for exhibition of malignant characteristics in T24 bladder cancer cells.

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Constitutive activation of Stat3 by the Src and JAK tyrosine kinases participates in growth regulation of human breast carcinoma cells

Cited by 667 publications

References 72 publications

EGF receptor‐mediated, c‐Src‐dependent, activation of Stat5b is downregulated in mitogenically responsive hepatocytes

EGF receptor‐mediated, c‐Src‐dependent, activation of Stat5b is downregulated in mitogenically responsive hepatocytes

Elevated phosphorylation and activation of PDK-1/AKT pathway in human breast cancer

Requirement of STAT3 activation for maximal collagenase-1 (MMP-1) induction by epidermal growth factor and malignant characteristics in T24 bladder cancer cells

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