Conjugated PDT drug: photosensitizing activity and tissue distribution of PEGylated pheophorbide a.

The design of new photosensitizers with enhanced phototoxicity and pharmacokinetic properties remains a central challenge for cancer photodynamic therapy (PDT). In this study, Pheophorbide a (Pba) has been pegylated to methoxypolyethylene glycol (mPE G-Pba) to produce a soluble photosensitizer that exhibits a higher tissue distribution than free Pba. In vitro studies have shown that mPE G-Pba promotes a fairly strong photosensitizing effect in cancer cells, as previously observed for the unpegylated molecule. mPE G-Pba targets the mitochondria where, following photoactivation, ROS are produced which cause a cellular injury by lipid peroxidation. The effect of pegylation on the photosensitizer biodistribution has been examined in different selected organs of female mice, at different time points after intraperitoneal administration of the drug (50 μmol/Kg body weight). Other than free Pba, which showed a low tissue accumulation, mPE G-Pba has been detected in significant amounts (8 to 16 μg/ml) in liver, spleen, duodenum and kidney and, 3-5 hours after intraperitoneal injection, in moderate amounts (3 to 8 μg/ml) in brain and lung. In vivo optical imaging performed on living female C57/BL6 mice bearing a subcutaneous melanoma mass, showed that injected mPEG-Pba distributes all over the body, with an higher uptake in the tumor respect to free Pba. Our results indicate that although pegylation somewhat decreases the phototoxicity, it significantly increases the drug solubility and tissue distribution and tumor uptake of mPE G-Pba, making the conjugate an interesting photosensitizer for PDT

Photosensitization of pancreatic cancer cells by cationic alkyl-porphyrins in free form or engrafted into POPC liposomes: The relationship between delivery mode and mechanism of cell death

Cationic porphyrins bearing an alkyl side chain of 14 (2b) or 18 (2d) carbons dramatically inhibit proliferation of pancreatic cancer cells following treatment with light. We have compared two different ways of delivering porphyrin 2d: either in free form or engrafted into palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine liposomes (L-2d). Cell cytometry shows that while free 2d is taken up by pancreatic cancer cells by active (endocytosis) and passive (membrane fusion) transports, L-2d is internalized solely by endocytosis. Confocal microscopy showed that free 2d co-localizes with the cell membrane and lysosomes, whereas L-2d partly co-localizes with lysosomes and ER. It is found that free 2d inhibits the KRAS-Nrf2-GPX4 axis and strongly triggers lipid peroxidation, resulting in cell death by ferroptosis. By contrast, L-2d does not affect the KRAS-Nrf2-GPX4 axis and activates cell death mainly through apoptosis. Overall, our study demonstrates for the first time that cationic alkyl porphyrins, which have a IC50 ~ 23 nM, activate a dual mechanism of cell death, ferroptosis and apoptosis, where the predominant form depends on the delivery mode

Potent virucidal activity in vitro of photodynamic therapy with Hpericum extract as photosensitizer and white light against human coronavirus HCoV-229E

The emergent human coronavirus SARS-CoV-2 and its high infectivity rate has highlighted the strong need for new virucidal treatments. In this sense, the use of photodynamic therapy (PDT) with white light, to take advantage of the sunlight, is a potent strategy for decreasing the virulence and pathogenicity of the virus. Here, we report the virucidal effect of PDT based on Hypericum extract (HE) in combination with white light, which exhibits an inhibitory activity of the human coronavirus HCoV-229E on hepatocarcinoma Huh-7 cells. Moreover, despite continuous exposure to white light, HE has long durability, being able to maintain the prevention of viral infection. Given its potent in vitro virucidal capacity, we propose HE in combination with white light as a promising candidate to fight against SARS-CoV-2 as a virucidal compoundThis research was funded by Fundación Universidad Autónoma de Madrid, grant number PI21/00315 and by Instituto de Salud Carlos III, grant number PI21/00953. Institutional Review Board Statement: Not applicabl

Efficient Silencing of bcr/abl Oncogene by Single- and Double-Stranded siRNAs Targeted against b2a2 Transcripts †

ABSTRACT: In this work, double- and single-stranded small-interference RNAs (siRNAs) were designed to knock down the bcr/abl oncogene in leukaemia KYO-1 cells. The siRNA molecules were targeted against two distinct sites encompassing the b2a2 junction of the bcr/abl transcripts. The siRNAs were able to reduce the levels of both bcr/abl mRNA and protein p210 BCR/ABL. Conversely, control siRNAs bearing 3 or 4 base-pair substitutions did not produce any inhibitory effect. The designed siRNAs were also found to be active in KCl22 cells, which harbor the b2a2 junction, but not in K562 cells, which, by contrast, harbor the b3a2 junction. The anti-b2a2 siRNAs promoted biological effects on KYO-1 cells, because the bcr/abl suppression resulted in the inhibition of cell growth and colony formation in agar and activation of apoptosis and upregulation of the cell-cycle inhibitor p27 protein. The bioactivity of the designed siRNAs is discussed in terms of internal stability of the RNA duplexes. Our data suggest that siRNAs can be considered strong tools for functional analysis of bcr/abl and for developing molecular therapeutic approaches to leukaemia. A reciprocal translocation between chromosomes 9 and 22, t(9;22), is found in more than 95 % of patients with chronic myeloid leukaemia (CML) 1 and in about 20 % o