Fibroblastoid mammary carcinoma cells photoinactivation employing an anthraquinone from Argentinean flora

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

Villa del Mar

Encuentro; 14th Encuentro Latinoamericano de Fotoquímica y Fotobiología, XIV ELAFOT; 2019

Comite organizador XIV ELAFOT

Parietin (PTN), an anthraquinone (AQ) found in some vegetal specieseven lichens, has proven to be a good photosensitizer with promisingapplications in bacterial photoinactivation. The aim of this work was toevaluate the in vitro activity of PTNas photosensitizer on a mammary carcinoma cell line in order to estimate itspotential use in Photodynamic Therapy (PDT) of cancer.PTN (1,8-dihydroxy-3-methoxy-6-methylanthraquinone) was isolatedfrom the lichen Teoloschistes nodulifer(Nyl.) Hillman (Teloschistaceae) and it was purified by recrystallization fromthe 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 doseinducing 50% of cell death after PDT treatment (at non cytotoxic concentrationof PTN, irradiation time ≤ 30 min) by employing the MTT colorimetric assay; b) sub-cellularlocalization of PTN by fluorescence microscopy; c) cellular morphology after PDTby optical microscopy crystal violet staining; and d) impactof PDT on cell migration, using a wound healing assay. LM2 cells were used atsemi confluency, PTN was prepared in RPMI medium with DMSO ≤ 1% and theirradiation doses were adjusted by employing different times of exposition to alight system, which consisted of 2 blue compact fluorescent lamps (Sica, 15 W).Results show that PTN (purity of 91.2 ± 0.2%) has a cytoplasmiclocalization (1h incubation) and exhibited a LD50 of 0.95 J/cm2 (3 min). PTN-PDTinduced morphological changes as well as condensed nuclei and cytoplasmicvacuolisation. Migration analysis suggested that whereas PTN per se induces a significant decrease oncell migration, migration index was impaired from 0.65 ± 0.04 to 0.30 ± 0.03after PTN-PDT. Therefore,this natural AQ that has a cytoplasmic target, induced cellkilling mediated by photodynamic sensitization and impaired the in vitro migration rate of mammarycarcinoma cells, at non cytotoxic concentrations and employing visible light.The results of this work confirm thepotential use of parietin in PDT, supporting the recommendations of the WorldHealth Organization to revalue phytomedicine and consider the healingproperties of the country's flora. Currently, we are carrying out in vivo studies of PTN-PDT on LM2 tumourbearing mice.