Effect of chirality on cellular uptake, imaging and photodynamic therapy of photosensitizers derived from chlorophyll-a.
We have previously shown that the (124)I-analog of methyl 3-(1'-m-iodobenzyloxy) ethyl-3-devinyl-pyropheophorbide-a derived as racemic mixture from chlorophyll-a can be used for PET (positron emission tomography)-imaging in animal tumor models. On the other hand, as a non-radioactive analog, it showed excellent fluorescence and photodynamic therapy (PDT) efficacy. Thus, a single agent in a mixture of radioactive ((124)I-) and non-radioactive ((127)I) material can be used for both dual-imaging and PDT of cancer. Before advancing to Phase I human clinical trials, we evaluated the activity of the individual isomers as well as the impact of a chiral center at position-3(1) in directing in vitro/in vivo cellular uptake, intracellular localization, epithelial tumor cell-specific retention, fluorescence/PET imaging, and photosensitizing ability. The results indicate that both isomers (racemates), either as methyl ester or carboxylic acid, were equally effective. However, the methyl ester analogs, due to subcellular deposition into vesicular structures, were preferentially retained. All derivatives containing carboxylic acid at the position-17(2) were noted to be substrate for the ABCG2 (a member of the ATP binding cassette transporters) protein explaining their low retention in lung tumor cells expressing this transporter. The compounds in which the chirality at position-3 has been substituted by a non-chiral functionality showed reduced cellular uptake, retention and lower PDT efficacy in mice bearing murine Colon26 tumors.
Photodynamic Therapy Center, Cell Stress Biology, Roswell Park Cancer Institute (RPCI), Buffalo, NY 14263, United States.
Avinash
A
Srivatsan
Photodynamic Therapy Center, Cell Stress Biology, Roswell Park Cancer Institute (RPCI), Buffalo, NY 14263, United States.
Paula
P
Pera
Photodynamic Therapy Center, Cell Stress Biology, Roswell Park Cancer Institute (RPCI), Buffalo, NY 14263, United States.
Penny
P
Joshi
Photodynamic Therapy Center, Cell Stress Biology, Roswell Park Cancer Institute (RPCI), Buffalo, NY 14263, United States.
Yanfang
Y
Wang
Photodynamic Therapy Center, Cell Stress Biology, Roswell Park Cancer Institute (RPCI), Buffalo, NY 14263, United States.
Joseph R
JR
Missert
Department of Molecular and Cellular Biology, Roswell Park Cancer Institute (RPCI), Buffalo, NY 14263, United States.
Erin C
EC
Tracy
Photodynamic Therapy Center, Cell Stress Biology, Roswell Park Cancer Institute (RPCI), Buffalo, NY 14263, United States.
Walter A
WA
Tabaczynski
Department of Nuclear Medicine, SUNY, Buffalo, NY 14221, United States.
Rutao
R
Yao
Department of Nuclear Medicine, SUNY, Buffalo, NY 14221, United States.
Munawwar
M
Sajjad
Department of Molecular and Cellular Biology, Roswell Park Cancer Institute (RPCI), Buffalo, NY 14263, United States. Electronic address: Heinz.Baumann@roswellpark.org.
Heinz
H
Baumann
Photodynamic Therapy Center, Cell Stress Biology, Roswell Park Cancer Institute (RPCI), Buffalo, NY 14263, United States. Electronic address: Ravindra.pandey@roswellpark.org.
Ravindra K
RK
Pandey
D000818:Animals; D001692:Biological Transport; D002294:Carcinoma, Squamous Cell / Q000378:metabolism / Q000473:pathology / Q000532:radiotherapy* / Q000648:ultrastructure; D045744:Cell Line, Tumor; D002734:Chlorophyll / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D000077194:Chlorophyll A; D003110:Colonic Neoplasms / Q000378:metabolism / Q000473:pathology / Q000532:radiotherapy* / Q000648:ultrastructure; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007457:Iodine Radioisotopes; D008175:Lung Neoplasms / Q000378:metabolism / Q000473:pathology / Q000532:radiotherapy* / Q000648:ultrastructure; D051379:Mice; D008807:Mice, Inbred BALB C; D057054:Molecular Imaging / Q000379:methods; D009368:Neoplasm Transplantation; D009928:Organ Specificity; D010778:Photochemotherapy / Q000379:methods; D017319:Photosensitizing Agents / Q000138:chemical synthesis / Q000494:pharmacology*; D053545:Spirulina / Q000737:chemistry; D013237:Stereoisomerism; D047368:Tumor Burden / Q000187:drug effects
D007457:Iodine Radioisotopes; D017319:Photosensitizing Agents; C505556:methyl 3-(1'-3-iodobenzyloxyethyl)-3-devinylpyropheophorbide-a; D002734:Chlorophyll; D000077194:Chlorophyll A
Cell-specificity; Chlorophyll-a; Imaging; Photodynamic therapy; Photosensitizer