phytochlorin and Fibrosarcoma

The controlled release of anticancer drugs at the tumor site is a central challenge in treating cancer. To achieve this goal, our strategy was based on tumor-specific targeting and ultrasound-triggered release of an anticancer agent from liposomal nanocarriers. To enhance the ultrasound-triggered drug release, we incorporated a lipophilic sonosensitizer, chlorin e6 (Ce6) ester, into the lipid bilayer of liposomes. Additionally, asparagine-glycine-arginine (NGR) that binds to CD13, which is overexpressed in tumor cells, was introduced into these liposomes. Under the navigation effects of the NGR, the novel ultrasound-triggerable NGR-modified liposomal nanocarrier (NGR/UT-L) accumulates in tumor sites. Once irradiated by ultrasound in tumor tissues, the sonodynamic effect produced by Ce6 could create more efficient disruptions of the lipid bilayer of the liposomal nanocarriers. After encapsulating doxorubicin (DOX) as the model drug, the ultrasound triggered lipid bilayer breakdown can spring the immediate release of DOX, making it possible for ultrasound-responsive chemotherapy with great selectivity. By combining tumor-specific targeting and stimuli-responsive controlled release into one system, NGR/UT-L demonstrated a perfect antitumor effect. Moreover, this report provides an example of controlled-release by means of a novel class of ultrasound triggering systems.

Topics: Animals; Antibiotics, Antineoplastic; CD13 Antigens; Cell Line, Tumor; Cell Survival; Chlorophyllides; Doxorubicin; Drug Carriers; Drug Delivery Systems; Drug Liberation; Fibrosarcoma; Humans; Lipid Bilayers; Liposomes; Mice; Mice, Nude; Oligopeptides; Porphyrins; Radiation-Sensitizing Agents; Tumor Burden; Ultrasonic Waves; Xenograft Model Antitumor Assays

A new approach to selective photodynamic therapy (PDT) was developed by designing chlorin e6 (Ce6)-containing macromolecules, which are sensitive to tumor-associated proteases. The agents are nontoxic in their native state but become fluorescent and produce singlet oxygen on protease conversion. Coupled with optimized delivery systems, we show that (a) the agents efficiently accumulate in tumors due to the enhanced permeability and retention effect, (b) the agents are locally activated by proteases, (c) local drug concentrations can be measured by quantitative fluorescence tomography, and (d) light-treated tumors show reduced growth. A single low dose of PDT (0.125 mg Ce6 equivalent/kg) was sufficient to suppress tumor growth by >50%. Activatable singlet oxygen generation agents provide increased efficacy with reduced toxicity, and it could become a powerful PDT.

Topics: Animals; Biotransformation; Cathepsin B; Chlorophyllides; Female; Fibrosarcoma; Humans; Mice; Mice, Nude; Photochemotherapy; Photosensitizing Agents; Porphyrins; Xenograft Model Antitumor Assays

Derivatives of porphyrin, specifically Fe-chlorin e6-Na (FeCNa), mimic superoxide dismutase (SOD). This SOD activity was determined by decrease in electron spin resonance (ESR) signals and increase in hydrogen peroxide (H2O2) as the intermediate of O2-. by the coloration using 4-aminoantipyrin. Chlorin e6-Na used for cancer photodynamic therapy (PDT)(1) does not show SOD mimicking activity. The specific activity of FeCNa, comparing with bovine RBC-SOD, was 1/7.5 as determined by ESR analysis. The iron element of Fe-chlorin e6-Na, being tightly encased in the molecule, did not participate in the Fenton reaction. The SOD mimetic activity of FeCNa was stable against physico-chemical treatment such as pH shock, heat and digestion by pronase. For cancer bearing rats with oxidative stress (OS), immediate relief of OS was possible by a single intraperitoneal injection of FeCNa and relief continued for 24 hours. The subsequent administration of FeCNa suppressed cancer growth in vivo.

Topics: Animals; Body Weight; Chlorophyllides; Electron Spin Resonance Spectroscopy; Fibrosarcoma; Hydrogen Peroxide; Injections, Intraperitoneal; Neoplasms, Experimental; Oxidative Stress; Oxygen; Porphyrins; Radiation-Sensitizing Agents; Rats; Rats, Wistar; Superoxide Dismutase

Transplantable rat tumours (sarcoma M-1, sarcoma 45, alveolar liver cancer PC-1 and Pliss' lymphosarcoma) were used to study chlorin e6 accumulation in tumours and its photodynamic effect. Tumours were irradiated by krypton ion laser light (647 and 676 nm; 90 J cm-2) 15 min and 24 h after chlorin e6 injection at doses of 5 and 10 mg kg-1. The relationship between some morphological peculiarities of these tumour strains, photosensitizer accumulation in tumours and their response to the photodynamic treatment is discussed.

Topics: Animals; Cell Division; Chlorophyllides; Female; Fibrosarcoma; Light; Liver Neoplasms; Lymphoma, Non-Hodgkin; Neoplasms, Experimental; Photochemotherapy; Porphyrins; Radiation-Sensitizing Agents; Rats; Rats, Wistar; Sarcoma, Experimental; Skin