RIBOFLAVIN ACETATE INDUCES APOPTOSIS IN SQUAMOUS CARCINOMA CELLS AFTER PHOTODYNAMIC THERAPY

JUAREZ, V; SOSA L DEL V.; DE PAUL, A L; COSTA A P; FARINA, M; LEAL, R; TORRES, AI; PONS, P

JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY

ELSEVIER SCIENCE SA

Lugar: Amsterdam; Año: 2015 vol. 153 p. 445 - 454

1011-1344

Several research efforts have been focused on finding newer and more efficient photosensitizers for photodynamictherapy (PDT). Although, it was demonstrated that riboflavin is an efficient photosensitizer for PDT, theeffect of its ester derivate, riboflavin 2′,3′,4′,5′-tetraacetate (RFTA), which has higher cellular uptake, has notbeen well defined. To evaluate the cell death generated by applying RFTA as the photosensitizer in PDT in ahuman cancer cell line of squamous carcinoma (SCC-13), these cells were incubated with riboflavin and itsester derivate, RFTA followed by irradiation with different blue light doses. Cell viability was evaluated using neutralred uptake assay and cell death was evaluated using transmission electron microscopy, TUNEL assay andannexin V-PE/7AAD double staining. The expression of caspase-3, Bax, Bcl-2, ERK 1/2 and p38MAPK was evaluatedby Western blotting and generation of intracellular ROS and changes in anion superoxide levels were analyzedusing 2′,7′-dichlorofluorescein-diacetate and dihydroethidium dye, respectively. RFTA-PDT generated a decreasein cancer cell viability in a light dose?response. Treated SCC-13 cells exhibited chromatin condensation,formation of apoptotic bodies, increases in TUNEL-positive cells, phosphatidylserine externalization anddecreased procaspase-3 and Bcl-2 protein expression and increment of ERK 1/2 phosphorylation. Moreover,trolox abolished the effect of PDT on cell viability linking the increase in intracellular ROS levels with the celldeath observed, whereas that the pre-treatment with MEK inhibitor did not induce changes in SCC-13 cellsurvival. These findings demonstrate the effects of RFTA in triggering apoptosis induced by ROS (?O2−) productionafter visible light irradiation of squamous carcinoma cells.