title: Intrinsic mitochondrial membrane potential change and associated events mediate apoptosis in chemopreventive effect of diclofenac in colon cancer.
abstract: The present study explored the role of intrinsic mitochondrial membrane potential (delta psi M) in NSAID-induced apoptosis in the early stages of colon cancer. 1,2-Dimethylhydrazine dihydrochloride (DMH) was used to induce colon cancer and its chemoprevention was studied by diclofenac in a rat model. After 6 weeks of treatment with DMH (early stage), morphological analysis revealed a marked occurrence of preneoplastic features [i.e., mucosal plaque lesions (MPLs) in the colonic tissue]. Coadministration of diclofenac with DMH resulted in a significant reduction of these lesions, thereby proving the chemopreventive efficacy of diclofenac at the chosen anti-inflammatory dose. DMH treatment also led to a significant increase in delta psi M in the isolated colonocytes as assessed by JC-1 fluorescent staining, measured both by fluorescence microscopy and spectrofluorometerically. Further, there was seen a reduction in the number of cells showing low delta psi M, and hence monomer intensity of JC-1 by DMH treatment. To study the mechanism of these alterations in delta psi M in the present work, we studied the protein expression of important proapoptotic proteins, cytochrome c and Bax, by Western blot analysis and immunohistochemistry. DMH treatment reduced the mitochondrial translocation of Bax whereas cytochrome c was found to be located prominently in the mitochondria. Protein expression of antiapoptotic Bcl-2 was also studied in the colonic mucosa, which was expectedly found to be overexpressed after DMH treatment. Diclofenac treatment ameliorated the elevated delta psi M and its associated events to exert its chemopreventive action against early stages of colon cancer.
authors.affiliation: Department of Biophysics, Panjab University, Chandigarh, India.
authors.forename: Jasmeet
authors.initials: J
authors.lastname: Kaur
authors.forename: S N
authors.initials: SN
authors.lastname: Sanyal
mesh_terms: D019813:1,2-Dimethylhydrazine; D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology*; D016588:Anticarcinogenic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D003110:Colonic Neoplasms / Q000139:chemically induced / Q000473:pathology / Q000517:prevention & control*; D045304:Cytochromes c / Q000378:metabolism; D004008:Diclofenac / Q000494:pharmacology*; D008297:Male; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects*; D010718:Phosphatidylserines / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D051028:bcl-2-Associated X Protein / Q000032:analysis
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D016588:Anticarcinogenic Agents; C494828:Bax protein, rat; D010718:Phosphatidylserines; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D004008:Diclofenac; D045304:Cytochromes c; D019813:1,2-Dimethylhydrazine