title: pH effects on the cellular uptake of four photosensitizing drugs evaluated for use in photodynamic therapy of cancer.
abstract: The difference in extracellular pH in malignant as compared to normal healthy tissues has been proposed to contribute to selective uptake of photosensitizers in tumors. Hematoporphyrin IX (HpIX), disulfonated meso-tetraphenylporphine (TPPS(2a)), meso-tetra(3-hydroxyphenyl)porphine (mTHPP) and meso-tetra(3-hydroxyphenyl)chlorin (mTHPC) were chosen to examine the pH dependence of their cellular drug uptake. The study was performed in the pH range 6.5-8.0 and showed that significantly higher amounts of the drug are taken up by T-47D cells at low pH values only in the case of HpIX. The pH value of the incubation medium did not influence the cellular uptake of mTHPP, mTHPC and TPPS(2a) significantly. The present work indicates that tumor selectivity of dyes, which get more lipophilic with decreasing pH value, may be related to the low extracellular pH value.
authors.affiliation: Department of Biophysics, Institute for Cancer Research, Montebello, N-0310 Oslo, Norway. eva.friberg@nrpa.no
authors.forename: Eva G
authors.initials: EG
authors.lastname: Friberg
authors.forename: Beata
authors.initials: B
authors.lastname: Cunderlíková
authors.forename: Erik O
authors.initials: EO
authors.lastname: Pettersen
authors.forename: Johan
authors.initials: J
authors.lastname: Moan
mesh_terms: D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology; D003470:Culture Media / Q000737:chemistry; D005110:Extracellular Space / Q000737:chemistry; D006414:Hematoporphyrin Photoradiation; D006415:Hematoporphyrins / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D008652:Mesoporphyrins / Q000737:chemistry / Q000378:metabolism*; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000737:chemistry / Q000378:metabolism*; D011166:Porphyrins / Q000737:chemistry / Q000378:metabolism*; D013329:Structure-Activity Relationship; D014407:Tumor Cells, Cultured / Q000378:metabolism
chemical_list: D003470:Culture Media; D006415:Hematoporphyrins; D008652:Mesoporphyrins; D017319:Photosensitizing Agents; D011166:Porphyrins; C425082:di(4-sulfonatophenyl)diphenylporphine; C437342:tetra(3-hydroxyphenyl)porphine; C037518:hematoporphyrin IX dimethylester; C072269:temoporfin