Fibroblastoid mammary carcinoma cells photoinactivation employing an anthraquinone from Argentinean flora

MUGAS, MARÍA LAURA; CÉSPEDES, MARIELA A.; NUÑEZ, SUSANA; MARIONI, JULIANA; DI VENOSA, GABRIELA; CALVO, GUSTAVO; SAENZ, DANIEL; ADRIANA CASAS

Villa del Mar

Congreso; 4th Encuentro Latinoamericano de Fotoquímica y Fotobiología, XIV ELAFOT; 2019

Comite organizador XIV ELAFOT

Parietin (PTN), an anthraquinone (AQ) found in some vegetal species even lichens, has proven to be a good photosensitizer with promising applications in bacterial photoinactivation. The aim of this work was to evaluate the in vitro activity of PTN as photosensitizer on a mammary carcinoma cell line in order to estimate its potential use in Photodynamic Therapy (PDT) of cancer.PTN (1,8-dihydroxy-3-methoxy-6-methylanthraquinone) was isolated from the lichen Teoloschistes nodulifer (Nyl.) Hillman (Teloschistaceae) and it was purified by recrystallization from the acetone extract, and its purity was determined by HPLC. We employed the murine mammary carcinoma cell line (LM2), originated from a mouse adenocarcinoma, and we determined: a) LD50: light dose inducing 50% of cell death after PDT treatment (at non cytotoxic concentration of PTN, irradiation time ≤ 30 min) by employing the MTT colorimetric assay; b) sub-cellular localization of PTN by fluorescence microscopy; c) cellular morphology after PDT by optical microscopy crystal violet staining; and d) impact of PDT on cell migration, using a wound healing assay. LM2 cells were used at semi confluency, PTN was prepared in RPMI medium with DMSO ≤ 1% and the irradiation doses were adjusted by employing different times of exposition to a light system, which consisted of 2 blue compact fluorescent lamps (Sica, 15 W). Results show that PTN (purity of 91.2 ± 0.2%) has a cytoplasmic localization (1h incubation) and exhibited a LD50 of 0.95 J/cm2 (3 min). PTN-PDT induced morphological changes as well as condensed nuclei and cytoplasmic vacuolisation. Migration analysis suggested that whereas PTN per se induces a significant decrease on cell migration, migration index was impaired from 0.65 ± 0.04 to 0.30 ± 0.03 after PTN-PDT. Therefore, this natural AQ that has a cytoplasmic target, induced cell killing mediated by photodynamic sensitization and impaired the in vitro migration rate of mammary carcinoma cells, at non cytotoxic concentrations and employing visible light.The results of this work confirm the potential use of parietin in PDT, supporting the recommendations of the World Health Organization to revalue phytomedicine and consider the healing properties of the country´s flora. Currently, we are carrying out in vivo studies of PTN-PDT on LM2 tumour bearing mice.