Activated signal transducer and activator of transcription 3 (STAT3) supports the malignant phenotype of human pancreatic cancer

doi:10.1016/S0016-5085(03)01064-3

Gastroenterology

Volume 125, Issue 3, September 2003, Pages 891-905

https://doi.org/10.1016/S0016-5085(03)01064-3 Get rights and content

Abstract

$Background & aims$ : Constitutive activation of signal transducer and activator of transcription 3 (STAT3) has been implicated in regulation of growth and malignant transformation. We therefore analyzed the expression and biologic significance of STAT3 in human pancreatic cancer cells. $Methods$ : Expression and activation of STAT3 were investigated by immunohistochemistry and immunoblotting. Functional inactivation of STAT3 was achieved by stable transfection of dominant-negative STAT3 constructs in 2 pancreatic cancer cell lines and confirmed by electrophoretic mobility shift assay and immunoblotting. Cell proliferation and tumorigenicity were evaluated by cell counting, colony formation in soft agar, and xenotransplantation in nude mice. STAT3-dependent cell cycle distribution was monitored by flow cytometry, immunoprecipitation, immunoblotting, and histone H1 and GST-Rb kinase assays. $Results$ : Compared with nontransformed human pancreas, activated STAT3 is overexpressed in ductal carcinoma cells but not in ducts from chronic pancreatitis. Constitutive activation was also observed in all human pancreatic cancer cell lines examined. Functional inactivation of STAT3 resulted in significant inhibition of anchorage-dependent and -independent proliferation in vitro and reduced tumor growth in vivo. Cell cycle analysis showed a delay of G₁/S-phase progression due to inhibition of cyclin-dependent kinase 2 activity based on increased expression of p21^WAF1 in vitro and in vivo. Blocking of the STAT3 upstream activator Janus kinase 2 by tyrphostin also resulted in growth arrest because of delayed G₁/S-phase progression and increased expression of p21^WAF1. $Conclusions$ : On malignant transformation, activated STAT3 promotes cellular proliferation by acceleration of G₁/S-phase progression and thereby contributes to the malignant phenotype of human pancreatic cancer.

Section snippets

Materials

The following were purchased: human pancreatic carcinoma cell lines AsPC-1, BxPC-3, CAPAN-1, CAPAN-2, MIA PaCA-2, and PANC-1 from American Type Tissue Culture Collection (Manassas, VA) and DAN-G cells from Deutsches Krebsforschungszentrum (Heidelberg, Germany); Dulbecco’s modified Eagle medium, RPMI 1640 medium, phosphate-buffered saline, glutamine and Geneticin (G418), Iscove’s modified Dulbecco’s modified Eagle medium, and Hyclone fetal calf serum (FCS) from Life Technologies (Karlsruhe,

Activated STAT3 is overexpressed in human pancreatic carcinoma

To evaluate the expression of activated STAT3 in human pancreatic cancer, we initially analyzed the prevalence of activated STAT3 in nontransformed pancreatic tissue, chronic pancreatitis, and ductal adenocarcinoma by using a phosphotyrosine-specific STAT3 antibody (p[tyr]-STAT3) that exclusively detects active STAT3. All carcinoma samples analyzed (n = 11) showed distinct nuclear p(tyr)-STAT3 staining in at least 35% of the ductal tumor cells (Figure 1C and D). In contrast, ductal epithelia

Discussion

In the current study, we show constitutive activation of STAT3 in human pancreatic cancer cells compared with their nontransformed counterparts. The mechanisms responsible for STAT3 activation on malignant transformation in the human pancreas are currently unknown. Activation of STAT3 can be observed in response to a plethora of stimuli, including growth factors, cytokines, oncoproteins, activated cytoplasmic kinases, or mitogenic receptors.11, 38 Our observation that considerable STAT3

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^☆: S.R. was supported by grants from Deutsche Krebshilfe, Wilhelm-Sander Stiftung, Else-Kröner-Fresenius Stiftung, Sonnenfeld Stiftung, and Deutsche Forschungs-gemeinschaft (DFG Ro 674/14–1). S.H. was supported by grants from Deutsche Forschungsgemeinschaft (Graduiertenkolleg 276/2).

¹: A.S. and S.H. contributed equally to this work.

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Basic-liver, pancreas, and biliary tractActivated signal transducer and activator of transcription 3 (STAT3) supports the malignant phenotype of human pancreatic cancer☆

Abstract

Section snippets

Materials

Activated STAT3 is overexpressed in human pancreatic carcinoma

Discussion

Eur J Cancer

Trends Biochem Sci

Gastroenterology

Immunity

Cell

Biochem Biophys Res Commun

Surg Oncol Clin North Am

Eur J Cancer

Gastroenterology

J Biol Chem

Pathol Res Pract

J Biol Chem

Biochem Biophys Res Commun

Cell Immunol

Biochim Biophys Acta

Cancer statistics, 1997

C A Cancer J Clin

Pancreatic cancer

Curr Treat Options Oncol

Pancreatic carcinoma

Lancet

Progress in cancer geneticslessons from pancreatic cancer

Ann Oncol

Tumor-suppressive pathways in pancreatic carcinoma

Cancer Res

Interferons as a paradigm for cytokine signal transduction

Cell Mol Life Sci

The nonsteroidal anti-inflammatory drug sulindac causes down-regulation of signal transducer and activator of transcription 3 in human oral squamous cell carcinoma cells

Cancer Res

A road map for those who know JAK-STAT

Science

STATs in oncogenesis

Oncogene

Serine phosphorylation of STATs

Oncogene

Targeted disruption of the mouse Stat3 gene leads to early embryonic lethality

Proc Natl Acad Sci U S A

Inhibition of constitutively activated Stat3 signaling pathway suppresses growth of prostate cancer cells

Cancer Res

Constitutive activation of Stat3 signaling abrogates apoptosis in squamous cell carcinogenesis in vivo

Proc Natl Acad Sci U S A

Constitutive activation of Stat3 in fibroblasts transformed by diverse oncoproteins and in breast carcinoma cells

Cell Growth Differ

Activated STAT signaling in human tumors provides novel molecular targets for therapeutic intervention

Clin Cancer Res

Requirement of Stat3 but not Stat1 activation for epidermal growth factor receptor-mediated cell growth in vitro

J Clin Invest

Enhanced DNA-binding activity of a Stat3-related protein in cells transformed by the Src oncoprotein

Science

Activation and association of Stat3 with Src in v-Src-transformed cell lines

Mol Cell Biol

Overexpression of pRB in human pancreatic carcinoma cellsfunction in chemotherapy-induced apoptosis

J Natl Cancer Inst

Basic-liver, pancreas, and biliary tract
Activated signal transducer and activator of transcription 3 (STAT3) supports the malignant phenotype of human pancreatic cancer☆