Gastroenterology

Gastroenterology

Volume 124, Issue 7, June 2003, Pages 1830-1845
Gastroenterology

Clinical-liver,pancreas, and biliary tract
Down-regulation of the dual-specificity phosphatase MKP-1 suppresses tumorigenicity of pancreatic cancer cells

https://doi.org/10.1016/S0016-5085(03)00398-6Get rights and content

Abstract

Background & Aims:

In both pancreatic cancer and chronic pancreatitis, there is enhanced expression of mitogenic growth factors and their tyrosine kinase receptors, which have the capacity to activate mitogen-activated protein kinase (MAPK). In view of the important role of MAPK kinase phosphatase (MKP)-1 in the regulation of MAPK activation, the expression and functional role of MKP-1 was analyzed.

Methods:

Pancreatic tissues were analyzed by Northern blotting, Western blotting, and immunohistochemistry. Pancreatic cancer cells were transfected with a full-length MKP-1 antisense construct. Growth characteristics and tumorigenicity in vivo and the effects of mitogenic growth factors on cell growth and MAPK activation were determined in transfected and control cells.

Results:

MKP-1 messenger RNA (mRNA) levels were increased in pancreatic cancer and chronic pancreatitis (CP) tissues. Moderate to strong MKP-1 immunoreactivity was present in the cancer cells, ductal cells of pancreatic intraepithelial neoplasia, and in tubular complexes in CP. Down-regulation of MKP-1 resulted in decreased anchorage-dependent and -independent growth of pancreatic cancer cells, and decreased tumorigenicity in a nude mouse tumor model. MKP-1 down-regulation led to decreased proliferation and sustained MAPK activation in response to mitogens.

Conclusions:

Suppression of MKP-1 expression reduces the tumorigenicity of pancreatic cancer cells in vivo, suggesting that MKP-1 contributes to enhanced mitogenic signaling in pancreatic cancer cells.

Section snippets

Tissue samples

Normal human pancreatic tissue samples (13 male, 7 female donors; median age 42 years; range 14–73 years), chronic pancreatitis tissues (18 male, 2 female; median age 47 years; range 30–60 years), and pancreatic cancer tissues (13 male, 8 female; median age 64 years; range 48–83 years) were obtained through an organ donor program and from surgical specimens obtained from patients with severe symptomatic chronic pancreatitis or from pancreatic cancer patients. According to the TNM classification

Mitogen-activated protein kinase phosphatase-1 expression in human pancreatic cancer and chronic pancreatitis

We first examined the expression levels of MKP-1 messenger RNA (mRNA) in pancreatic cancer specimens and normal pancreatic tissues. Northern blot analysis of total RNA isolated from 21 cancerous and 20 normal pancreatic tissues revealed the presence of the 2.4-kb MKP-1 transcript7 at relatively low levels in 7 of 20 (35%) normal pancreatic samples. In the remaining samples the MKP-1 transcript was detectable only on the original autoradiographs. In contrast, in 12 of 21 (57%) pancreatic cancer

Discussion

MAPKs, which include the extracellular signal-regulated kinases (p42 and p44-MAPK), the c-Jun N-terminal kinases (JNK/SAPK), and p38-MAPK, play a pivotal role in cell proliferation and differentiation.3 Their function can be modulated by reversible phosphorylation. MAPKs are activated through complex phosphorylation cascades, in which a series of phosphorylation events occur by Raf (MAPKKK) and MEK (MAPKK),4 and their activation in turn leads to the phosphorylation and activation of a variety

References (46)

  • H. Friess et al.

    Enhanced expression of transforming growth factor beta isoforms in pancreatic cancer correlates with decreased survival

    Gastroenterology

    (1993)
  • A.B. Raitano et al.

    Tumor necrosis factor up-regulates gamma-interferon binding in a human carcinoma cell line

    J Biol Chem

    (1990)
  • R.J. Davis

    The mitogen-activated protein kinase signal transduction pathway

    J Biol Chem

    (1993)
  • Y. Liu et al.

    Age-related decline in mitogen-activated protein kinase activity in epidermal growth factor-stimulated rat hepatocytes

    J Biol Chem

    (1996)
  • C.J. Marshall

    Specificity of receptor tyrosine kinase signalingtransient versus sustained extracellular signal-regulated kinase activation

    Cell

    (1995)
  • Y.R. Chen et al.

    The role of c-Jun N-terminal kinase (JNK) in apoptosis induced by ultraviolet C and gamma radiation. Duration of JNK activation may determine cell death and proliferation

    J Biol Chem

    (1996)
  • H. Kazama et al.

    Oncogenic K-Ras and basic fibroblast growth factor prevent Fas-mediated apoptosis in fibroblasts through activation of mitogen-activated protein kinase

    J Cell Biol

    (2000)
  • S.L. Pelech et al.

    MAP kinasescharting the regulatory pathways

    Science

    (1992)
  • J. Wu et al.

    Molecular structure of a protein-tyrosine/threonine kinase activating p42 mitogen-activated protein (MAP) kinaseMAP kinase kinase

    Proc Natl Acad Sci U S A

    (1993)
  • K.Z. Guyton et al.

    Mitogen-activated protein kinase (MAPK) activation by butylated hydroxytoluene hydroperoxideimplications for cellular survival and tumor promotion

    Cancer Res

    (1996)
  • C.C. Franklin et al.

    Conditional expression of mitogen-activated protein kinase phosphatase-1, MKP-1, is cytoprotective against UV-induced apoptosis

    Proc Natl Acad Sci U S A

    (1998)
  • M. Mayr et al.

    Biomechanical stress-induced apoptosis in vein grafts involves p38 mitogen-activated protein kinases

    FASEB J

    (2000)
  • S. Srikanth et al.

    Human DU145 prostate cancer cells overexpressing mitogen-activated protein kinase phosphatase-1 are resistant to Fas ligand-induced mitochondrial perturbations and cellular apoptosis

    Mol Cell Biochem

    (1999)
  • Cited by (0)

    Supported in part by USPHS grant CA-40162 awarded by the National Cancer Institute (to M.K.).

    1

    Q.L., J.G., and J.K. contributed equally to this work.

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