chlorophyll-a and Carcinoma

Photodynamic therapy (PDT) is an established therapeutic method, first approved by the FDA for certain kinds of cancer in 1998. There are also increasing data to show that a related procedure, sonodynamic therapy (SDT), is a promising new modality for cancer treatment. Here, the authors report clinical results in 3 advanced refractory breast cancer patients who were treated using a combination of sonodynamic and photodynamic therapy (SPDT), along with conventional therapies. All 3 patients had pathologically proven metastatic breast carcinoma. These widely disseminated carcinomas had ultimately failed to respond to conventional therapy. A new sensitizing agent, Sonoflora 1 (SF1) was administered sublingually; then, after a 24-hour delay, patients were treated with a combination of light and ultrasound. All patients had significant partial or complete responses. SPDT is a promising new therapeutic combination for the treatment of breast cancer.

Topics: Administration, Sublingual; Adult; Breast Neoplasms; Carcinoma; Chlorophyll; Combined Modality Therapy; Complementary Therapies; Fatal Outcome; Female; Humans; Middle Aged; Neoplasm Metastasis; Photochemotherapy; Photosensitizing Agents; Positron-Emission Tomography; Treatment Outcome; Ultrasonic Therapy

Pharmacokinetics and phototoxicity of purpurin-18 (Pp18) in human colon carcinoma cells (Colo-205) was studied using liposomes as delivery vehicles. Cytotoxicity was measured using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and neutral red uptake assay, and mode of cell death was assessed by the study of cell morphology and nuclear staining with Hoechst 33342-propidium iodide. Pp18 solubilized in dimethyl sulfoxide saline solution was observed to aggregate (Q-band absorption 740 nm), resulting in very poor cellular uptake. Pp18 incorporated in liposome remained in monomeric form (Q-band absorption 695 nm), but due to the presence of an anhydride ring in the molecule it readily yielded another photosensitizer, chlorin p6 (Q-band absorption 662 nm). Measurements at various pH showed that Pp18 in liposome was stable at acidic pH (6.5). Incubation of cells with 6.0 microM Pp18 in liposome at pH 6.5 showed a rapid cellular uptake. Spectrofluorometric measurements showed the presence of both Pp18 and chlorin p6, indicating conversion of some amount of Pp18 into chlorin p6 in the cells. Fluorescence microscopy revealed that the fluorescence was localized mainly in the cytoplasm, sparing the nucleus. Illumination of cells to white light after 4-h incubation with Pp18 liposome preparation was observed to lead to dose-dependent decrease in cell viability. At low irradiation time, cells displayed formation of plasma membrane blebs and micronuclei typical of apoptotic cell death. In contrast, at higher irradiation time, cell swelling and vacuolization in nucleus was observed, suggesting cell death due to necrosis. Irradiation with narrow bandwidth light showed that at low pH, the relative phototoxicity due to pp18 was higher than that due to chlorin p6. It is suggested that the pH-dependent conversion of pp18 to chlorin p6 can be exploited to increase PDT selectivity.

Topics: Carcinoma; Cell Death; Cell Line, Tumor; Chlorophyll; Colonic Neoplasms; Dermatitis, Phototoxic; DNA Fragmentation; Drug Delivery Systems; Humans; Hydrogen-Ion Concentration; Liposomes; Neutral Red; Phosphatidylcholines; Porphyrins; Radiation-Sensitizing Agents

We propose the use of acetoxymethyl esters of pH-sensitive amphipathic photosensitizers (PS) for photodynamic therapy (PDT). These compounds may be applicable for PDT involving endocytosis of lipophilic carriers leading to lysosomal uptake of the esterified PS by target cells. Partial and/or total enzymatic de-esterification may result in the extralysosomal distribution of the photoactive agents, possibly culminating in a multisite photochemical response. We report here the synthesis and properties of chlorin e6 triacetoxymethyl ester (CAME) and pheophorbide a acetoxymethyl ester (PAME). Chlorin e6 and pheophorbide a are photocytotoxic chlorins that possess free carboxylate groups and exhibit optimum wavelengths of excitation substantially red shifted relative to hematoporphyrin derivative. Acetoxymethyl esterification of chlorin e6 and pheophorbide a was accomplished with bromomethyl acetate. High-performance liquid chromatography allowed for the purification of PAME, in 87% purity, and CAME, in 63% yield and 94% purity, as well as the detection of the presumed mono- and diesters of chlorin e6 as transient intermediates in the synthesis of CAME. The ultraviolet-visible absorption, fluorescence excitation and emission, NMR and mass spectra of the chlorin e6 triester are consistent with those expected for CAME. The pH-sensitive amphipathicity of pheophorbide a and chlorin e6 but not CAME was demonstrated using a water/1-octanol partition assay. The production of pheophorbide a from PAME and the sequential formation of the di- and monoesters and free chlorin e6 from CAME, by the action of lysosomal esterases obtained from cancer cells, demonstrate the potential of cellular enzymes to convert the lipophilic esters to pH-sensitive amphipathic PS.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Carcinoma; Chlorophyll; Chlorophyllides; Esterases; Esterification; Esters; Humans; Hydrogen-Ion Concentration; Lysosomes; Photosensitizing Agents; Porphyrins; Solubility; Spectrometry, Fluorescence; Spectrophotometry; Urinary Bladder Neoplasms

In recent years porphyrins and related materials have been tested as antitumor agents. A technique was devised to obtain dose-response curves for the sensitizer fraction that resists one day of elution by tissue culture medium--the retained fraction. We found a steep "threshold" dose response relationship that helps to explain tumor destruction without damage to normal tissues. The family of dose-response curves produced by a wide range of light exposures suggests that chlorins and porphyrins do not act by identical mechanisms. Moreover, they suggest that chlorins will prove superior in practical use.

Topics: Carcinoma; Cell Survival; Chlorophyll; Chlorophyllides; Colonic Neoplasms; Dose-Response Relationship, Drug; Dose-Response Relationship, Radiation; Hematoporphyrins; Humans; Light; Porphyrins; Tumor Cells, Cultured

Topics: Carcinoma; Chlorophyll; Female; Humans; Iodized Oil; Lymphatic Metastasis; Lymphography; Uterine Cervical Neoplasms

Topics: Carcinoma; Carcinoma, Basal Cell; Chlorophyll; Enzymes; Humans; Skin Neoplasms