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Opioid growth factor regulates the cell cycle of human neoplasias

I S Zagon1, C D Roesener, M F Verderame

  • 1Department of Neuroscience and Anatomy, H-109, The Pennsylvania State University, College of Medicine, Hershey, PA 17033, USA. isz1@psu.edu

International Journal of Oncology
|October 13, 2000
PubMed

Insights

The opioid growth factor (OGF) inhibits cancer cell proliferation by targeting the G0/G1 phase of the cell cycle. Blocking OGF-OGFr interaction with naltrexone (NTX) accelerates cancer cell growth and disrupts cell cycle progression.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Cancer Research

Background:

  • The opioid growth factor (OGF), [Met5]-enkephalin, is a peptide that regulates cell proliferation and tissue organization.
  • OGF exerts its effects through the OGF receptor (OGFr).
  • Dysregulation of OGF-OGFr signaling is implicated in various biological processes, including cancer development.

Purpose of the Study:

  • To investigate the role of OGF in regulating cancer cell proliferation.
  • To determine the specific phase of the cell cycle targeted by OGF.
  • To examine the effects of OGF-OGFr interaction blockade on cancer cell cycle progression.

Main Methods:

  • Experiments were conducted on three human cancer cell lines: pancreatic (BxPC-3), colon (HT-29), and head and neck (CAL-27).
  • The effects of excess OGF and naltrexone (NTX), an opioid antagonist, on cell proliferation were assessed.
  • Flow cytometry (FACS) analysis and percentage of labeled mitosis (PLM) were used to evaluate cell cycle distribution and kinetics.

Main Results:

  • OGF exposure decreased cancer cell growth, DNA synthesis, and mitosis, increasing doubling time and accumulating cells in the G0/G1 phase.
  • Naltrexone (NTX) blockade of OGF-OGFr interaction accelerated cell growth, shortened DNA synthesis and mitotic phases, and reduced cells in G0/G1 phase.
  • FACS and PLM analyses confirmed that OGF targets the G0/G1 phase, while NTX-induced blockade caused significant cell cycle perturbations.

Conclusions:

  • OGF acts as a crucial inhibitor of cancer cell proliferation, primarily by regulating the G0/G1 phase.
  • Interruption of the OGF-OGFr pathway by naltrexone (NTX) has profound and detrimental effects on cancer cell cycle progression.
  • These findings highlight the importance of the OGF-OGFr axis in controlling cell proliferation and suggest its potential as a therapeutic target in cancer treatment.

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