PTEN regulates apoptotic cell death through PI3-K/Akt/GSK3β signaling pathway in DMH induced early colon carcinogenesis in rat

Exp Mol Pathol. 2012 Aug;93(1):135-46. doi: 10.1016/j.yexmp.2012.04.019. Epub 2012 Apr 25.


Phosphatidylinositol 3-kinase (PI3-K) and Akt (protein kinase B), are both essential signaling molecules that are up-regulated in various cancers. Here, we examined the molecular mechanisms by which PI3-K and Akt expression are regulated by glycogen synthase kinase-3β (GSK-3β) and the phosphatase and tensin homolog deleted on chromosome 10 (PTEN) in the early stages of experimental colon carcinogenesis. 1,2-dimethylhydrazine (DMH) was utilized for the induction of colon cancer while piroxicam, a traditional non-steroidal anti-inflammatory drug and c-phycocyanin, a biliprotein from Spirulina platensis (cyanobacterium) as the chemopreventive agents. Western blotting and immunofluorescence results indicated that the expression of PI3-K and Akt was promoted in the DMH group while least apoptosis was detected in this group as analyzed by Hoechst 33342-propidium iodide co-staining. DMH group further detected lower GSK-3β and PTEN expression as compared to other groups. Piroxicam and c-phycocyanin treatment resulted significant apoptotic cell death while showing low PI3-K and Akt expressions. Mitochondrial membrane potential (ΔΨ(M)) alterations (examined by JC-1 and rhodamine 123 labeling of colonocytes) and fluorescence intensity measurement of ROS level, were also analyzed showing the raised ΔΨ(M) while reduced ROS levels in DMH group, however piroxicam and c-phycocyanin treatment resulted in falling of ΔΨ(M) although both stimulated the ROS production as analyzed by flow cytometry. The present study thus identified that piroxicam, a traditional NSAID and c-phycocyanin, a newly discovered COX-2 selective inhibitor, constitute remarkable chemopreventive targets in mediating apoptosis in the DMH induced early rat colon carcinogenesis via regulating PI3-K/Akt/GSK-3β/PTEN signaling pathways. Further, a combination of the two drugs provides a better therapeutic option, than the monotherapy regimen.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anti-Inflammatory Agents, Non-Steroidal / pharmacology
  • Apoptosis
  • Carcinogens / toxicity
  • Carcinoma / chemically induced
  • Carcinoma / metabolism
  • Carcinoma / prevention & control
  • Cell Transformation, Neoplastic / chemically induced
  • Cell Transformation, Neoplastic / drug effects
  • Colonic Neoplasms / chemically induced
  • Colonic Neoplasms / metabolism*
  • Colonic Neoplasms / prevention & control
  • Cyclooxygenase 2 Inhibitors / pharmacology
  • Dimethylhydrazines / toxicity
  • Drug Therapy, Combination
  • Glycogen Synthase Kinase 3 / metabolism*
  • Glycogen Synthase Kinase 3 beta
  • Male
  • Membrane Potential, Mitochondrial / drug effects
  • PTEN Phosphohydrolase / physiology*
  • Phosphatidylinositol 3-Kinase / biosynthesis*
  • Phycocyanin / pharmacology
  • Piroxicam / pharmacology
  • Proto-Oncogene Proteins c-akt / biosynthesis*
  • Rats
  • Rats, Sprague-Dawley
  • Reactive Oxygen Species / metabolism


  • Anti-Inflammatory Agents, Non-Steroidal
  • Carcinogens
  • Cyclooxygenase 2 Inhibitors
  • Dimethylhydrazines
  • Reactive Oxygen Species
  • Phycocyanin
  • Piroxicam
  • Phosphatidylinositol 3-Kinase
  • Glycogen Synthase Kinase 3 beta
  • Gsk3b protein, rat
  • Proto-Oncogene Proteins c-akt
  • Glycogen Synthase Kinase 3
  • PTEN Phosphohydrolase
  • Pten protein, rat