title: P2X7 receptor as a novel drug delivery system to increase the entrance of hydrophilic drugs into cells during photodynamic therapy.
abstract: The second-generation photosensitizer methylene blue (MB) exhibits photochemical and photophysical properties suitable for photodynamic therapy (PDT)-based cancer treatment. However, the clinical application of MB is limited because of its high hydrophilicity, which hinders its penetration into tumor tissues. Therefore, new methods to improve the entry of MB into the cytoplasm of target cells are necessary. Because MB has a mass of 319 Da, transient pores on the plasma membrane, such as the pore induced by the P2X7 receptor (P2X7R) that allows the passage of molecules up to 900 Da, could be used. Using MTT viability assays, flow cytometry experiments, and fluorescence microscopy, we evaluated the toxicity and phototoxicity of MB and potentiation effects of ATP and MB on cell death processes in the J774 cell line (via a P2X7-associated pore). We observed that treatment with 5 μM MB for 15 min promoted the rate of entry of MB into the cytoplasm to 4.7 %. However, treatment with 5 μM MB and 1 mM ATP for the same amount of time increased this rate to 90.2 %. However, this effect was inhibited by pretreatment with a P2X7 antagonist. We used peritoneal macrophages and a cell line that does not express P2X7R as controls. These cells were more resistant to PDT with MB under the same experimental conditions. Taken together, these results suggest the use of the pore associated with P2X7R as a drug delivery system to increase the passage of hydrophilic drugs into cells that express this receptor, thus facilitating PDT.
authors.affiliation: Laboratório de Comunicação Celular, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, Brasil.
authors.forename: Paulo Anastácio Furtado
authors.initials: PA
authors.lastname: Pacheco
authors.affiliation: Laboratório de Inflamação, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, Brasil.
authors.forename: Leonardo Braga Gomes
authors.initials: LB
authors.lastname: Ferreira
authors.affiliation: Laboratório de Comunicação Celular, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, Brasil.
authors.forename: Leonardo
authors.initials: L
authors.lastname: Mendonça
authors.affiliation: Laboratório de Comunicação Celular, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, Brasil.
authors.forename: Dinarte Neto M
authors.initials: DN
authors.lastname: Ferreira
authors.affiliation: Laboratório de Toxoplasmose, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz - FIOCRUZ, Av. Brasil, 4365 Manguinhos - CEP, :21045-900, Rio de Janeiro, RJ, Brasil.
authors.forename: Juliana Pimenta
authors.initials: JP
authors.lastname: Salles
authors.affiliation: Laboratório de Toxoplasmose, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz - FIOCRUZ, Av. Brasil, 4365 Manguinhos - CEP, :21045-900, Rio de Janeiro, RJ, Brasil. robson.xavier@gmail.com.
authors.forename: Robson Xavier
authors.initials: RX
authors.lastname: Faria
authors.affiliation: Laboratório de Comunicação Celular, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, Brasil.
authors.forename: Pedro Celso Nogueira
authors.initials: PC
authors.lastname: Teixeira
authors.affiliation: Laboratório de Comunicação Celular, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, Brasil.
authors.forename: Luiz Anastacio
authors.initials: LA
authors.lastname: Alves
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D016923:Cell Death / Q000187:drug effects; D002460:Cell Line; D002463:Cell Membrane Permeability / Q000187:drug effects; D002478:Cells, Cultured; D016503:Drug Delivery Systems / Q000379:methods*; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008264:Macrophages / Q000166:cytology; D008751:Methylene Blue / Q000493:pharmacokinetics / Q000633:toxicity; D051379:Mice; D010778:Photochemotherapy / Q000379:methods*; D016062:Porosity; D058486:Receptors, Purinergic P2X7 / Q000627:therapeutic use*
chemical_list: D058486:Receptors, Purinergic P2X7; D000255:Adenosine Triphosphate; D008751:Methylene Blue
keywords: Methylene blue; P2X7 receptor; Photodynamic therapy; Pore