Anticancer activities of harmine by inducing a pro-death autophagy and apoptosis in human gastric cancer cells

Phytomedicine. 2017 May 15;28:10-18. doi: 10.1016/j.phymed.2017.02.008. Epub 2017 Feb 28.

Abstract

Background: Harmine, a β-carboline alkaloid from Peganum harmala, has multiple anti-tumor activities, especially for its folk therapy for digestive system neoplasm. However, the underlying mechanism of harmine on gastric cancer remains unclear.

Purpose: To illuminate the potential anti-tumor activity and mechanism of harmine against gastric cancer cells.

Methods/study designs: The anti-proliferative activity of harmine in vitro was evaluated by MTT assay. The autophagic activity induced by harmine was assessed using GFP-LC3 transfection. FITC/PI double staining was applied for the apoptosis inspection. The mitochondrial membrane potential was detected by JC-1 fluorescence probe. The potential mechanisms for proteins level in autophagy and apoptosis were analyzed by Western blot.

Results: Harmine exhibited potent effects on both autophagy and apoptosis. Treatment with harmine could enhance dots of GFP-LC3 in cells. Meanwhile, the process had connection with Beclin-1, LC3-II, and p62 by the inhibition of Akt/mTOR/p70S6K signaling. However, high concentration of harmine led to apoptosis characterized by the propidium/Annexin V-positive cell pollution, cell shrunk and the collapse of mitochondrial membrane potential. The regulation of Bcl-2, Bax and the gathering of cleaved-PARP, cleaved-caspase 3 and cleaved-caspase 9 contributed to the induction of apoptosis. In addition, 10μM LY294002 (a specific inhibitor of PI3K/Akt) combination with 40μM harmine significantly increased the cytotoxicity to the gastric cancer cells and up-regulated both the apoptosis-related protein (cleaved-PARP, cleaved-caspase-3) and autophagy-related protein (Beclin-1, LC3-II, and p62). Adding the inhibitor of autophagy, 3-MA or BafA1, increased the viability of harmine-exposured gastric cancer cells, which confirmed the role of autophagy played in the gastric cancer cell death induced by harmine.

Conclusion: Harmine might be a potent inducer of apoptosis and autophagy, which offered evidences to therapy of harmine in gastric carcinoma in the folk medicine.

Keywords: Apoptosis; Autophagy; Gastric cancer; Harmine; mTOR.

MeSH terms

  • Antineoplastic Agents, Phytogenic / pharmacology*
  • Apoptosis / drug effects
  • Apoptosis Regulatory Proteins / metabolism
  • Autophagy / drug effects*
  • Beclin-1 / metabolism
  • Caspase 3 / metabolism
  • Caspase 9 / metabolism
  • Cell Line, Tumor
  • Drug Screening Assays, Antitumor / methods
  • Harmine / pharmacology*
  • Humans
  • Membrane Potential, Mitochondrial / drug effects
  • Phosphatidylinositol 3-Kinases / metabolism
  • Signal Transduction / drug effects
  • Stomach Neoplasms / drug therapy*
  • Stomach Neoplasms / metabolism
  • Stomach Neoplasms / pathology

Substances

  • Antineoplastic Agents, Phytogenic
  • Apoptosis Regulatory Proteins
  • BECN1 protein, human
  • Beclin-1
  • Harmine
  • Phosphatidylinositol 3-Kinases
  • Caspase 3
  • Caspase 9