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The zinc-finger transcription factor Snail downregulates proliferating cell nuclear antigen expression in colorectal

Jae-Hong Park1, Ik-Joo Sung, Sae-Won Lee

  • 1Department of Molecular Biology, Pusan National University, Busan 609-735, Korea.

International Journal of Oncology
|May 5, 2005
PubMed

Insights

The Snail protein represses the PCNA gene, inhibiting cell proliferation in colorectal cancer cells. This study identifies PCNA as a novel Snail target gene, impacting tumor progression.

Area of Science:

  • Molecular Biology
  • Cancer Research
  • Gene Regulation

Background:

  • Snail family proteins are transcription repressors crucial for embryonic development and tumor progression.
  • They regulate diverse cellular processes including differentiation, motility, cell cycle, and apoptosis.
  • However, specific target genes of Snail remain largely unidentified.

Purpose of the Study:

  • To investigate the potential role of Snail as a regulator of the human PCNA gene.
  • To determine if Snail directly binds to the PCNA promoter and affects its activity.
  • To explore the impact of Snail on cell proliferation via PCNA regulation in colorectal cancer.

Main Methods:

  • Bioinformatic analysis to identify potential Snail binding sites in the human PCNA 5'-flanking region.
  • Cotransfection assays in colorectal carcinoma cell lines (HCT116, Colo320HSR) to assess promoter activity.
  • Immunoblotting and immunochemistry to detect PCNA protein expression levels.
  • Bromodeoxyuridine (BrdU) incorporation assays to measure cell proliferation.
  • Electrophoretic mobility shift assays (EMSAs) to confirm Snail-PCNA promoter binding.

Main Results:

  • Potential Snail binding sequences were identified in the human PCNA gene's 5'-flanking region.
  • Snail significantly reduced PCNA gene promoter activity in colorectal cancer cell lines.
  • Snail expression led to decreased PCNA protein levels and inhibited BrdU incorporation.
  • EMSAs confirmed direct binding of Snail to the identified recognition sites on the human PCNA promoter.

Conclusions:

  • Snail directly targets the human PCNA gene promoter.
  • Snail down-regulates PCNA expression, suggesting an inhibitory effect on cell proliferation.
  • PCNA is identified as a novel target gene of Snail, implicating Snail in the regulation of cell proliferation during tumor progression.

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