title: Extracellular pH influences the mode of cell death in human colon adenocarcinoma cells subjected to photodynamic treatment with chlorin p6.
abstract: Effect of varying extracellular pH on mode of cell death induced by photodynamic action of chlorin p6 was investigated in human colon carcinoma (Colo-205) cells. At an extracellular pH of 7.4, compared to cells treated with chlorin p6 in dark, the photodynamically treated cells showed reduction in mitochondrial membrane potential, an increase in ADP/ATP ratio (1:2) and a large percentage of cells with chromatin condensation. In contrast, when photodynamic treatment and post irradiation incubation was carried out in acidic medium (pH 6.5), total loss of mitochondrial membrane potential, a marked increase in ADP/ATP ratio (1:33) and increased damage to plasma membrane were observed. Further, cells subjected to photodynamic treatment in a medium of pH 7.4 showed twofold increase in caspase-3 activity as compared to photodynamic treatment at pH 6.5. These results suggest that chlorin p6 mediated photodynamic action induces apoptotic cell death when extracellular pH is 7.4 whereas necrosis is more predominant under condition when extracellular pH is 6.5.
authors.affiliation: Biomedical Applications Section, Laser Fusion Laboratory, Centre for Advanced Technology, Indore 452013, India. msharma@cat.ernet.in
authors.forename: Mrinalini
authors.initials: M
authors.lastname: Sharma
authors.forename: Khageswar
authors.initials: K
authors.lastname: Sahu
authors.forename: Alok
authors.initials: A
authors.lastname: Dube
authors.forename: Pradeep Kumar
authors.initials: PK
authors.lastname: Gupta
mesh_terms: D000230:Adenocarcinoma / Q000378:metabolism / Q000473:pathology*; D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000378:metabolism / Q000473:pathology*; D005110:Extracellular Space / Q000737:chemistry*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008564:Membrane Potentials; D008928:Mitochondria / Q000201:enzymology / Q000378:metabolism / Q000502:physiology; D010778:Photochemotherapy; D011166:Porphyrins / Q000494:pharmacology*
chemical_list: D011166:Porphyrins; C072905:chlorin p6; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases