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Negative regulation of hepatocellular carcinoma cell growth by signal regulatory protein alpha1

He-Xin Yan1, Hong-Yang Wang, Rui Zhang

  • 1International Cooperation Laboratory on Signal Transduction, Eastern Hepatobiliary Surgery Institute, Second Military Medical University, Shanghai, China.

Hepatology (Baltimore, Md.)
|September 7, 2004
PubMed

Insights

Signal regulatory protein alpha1 (SIRPalpha1) suppresses liver cancer growth by inhibiting key signaling pathways. Restoring SIRPalpha1 levels in hepatocellular carcinoma cells reduced tumor progression and metastasis.

Area of Science:

  • Molecular Biology
  • Cancer Research
  • Immunology

Background:

  • Signal regulatory protein alpha1 (SIRPalpha1) is a tyrosine-phosphorylated protein that interacts with SHP-2 phosphatase.
  • SIRPalpha1 expression is often reduced in hepatocellular carcinoma (HCC) tissues.

Purpose of the Study:

  • To investigate the role of SIRPalpha1 in hepatocellular carcinoma (HCC) progression.
  • To elucidate the molecular mechanisms by which SIRPalpha1 regulates HCC cell behavior.

Main Methods:

  • Utilized SIRPalpha1-negative Huh7 HCC cells for transfection with wild-type or mutant SIRPalpha1.
  • Stimulated cells with epidermal growth factor (EGF) or hepatocyte growth factor (HGF) to induce phosphorylation and complex formation.
  • Assessed tumor cell growth, proliferation, signaling pathway activation (ERK, NF-kappaB), cell death sensitivity, migration, and spreading.

Main Results:

  • Exogenous expression of wild-type SIRPalpha1 suppressed HCC cell growth in vitro and in vivo.
  • SIRPalpha1 phosphorylation and SHP-2 binding were induced by EGF/HGF, leading to reduced ERK1 activation.
  • SIRPalpha1 expression inhibited NF-kappaB activation and sensitized cells to TNFalpha/cisplatin-induced death.
  • SIRPalpha1-mediated suppression of cell migration and spreading was dependent on SHP-2 complex formation.

Conclusions:

  • SIRPalpha1 acts as a negative regulator of hepatocarcinogenesis.
  • SIRPalpha1 exerts its tumor-suppressive effects partly by inhibiting ERK and NF-kappaB pathways.
  • SIRPalpha1-SHP-2 interaction is crucial for its anti-migratory and anti-metastatic functions in HCC.

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