EFFECT OF INHIBITION OF THE WNT PATHWAY IN BASAL-LIKE MAMMARY TUMOR CELLS

PETRIZ OTAÑO LUCÍA; FELCHER, CARLA M.; MOSNA M JIMENA; GARDE FEDERICO; STINSON MARCELO; DI BELLA DANIELA; KORDON EDITH; CARCAGNO ABEL

Mar del Plata

Congreso; Reunión Anual SAIC 2022; 2022

SAIC

In 2020, breast cancer ranked first regarding cancer incidence andmortality worldwide. Basal-like tumors represent approximately 15-20% of all breast cancers and show aggressive behavior, with a highprobability of recurrence and few specific therapies. Our aim was tostudy in vitro and in ovo the effects of knocking down R-spondin 3(Rspo3), which (as demonstrated previously) enhances the canonicalWnt pathway in the SCg6 basal-like tumor cell line. Using flowcytometry assays with Propidium Iodide staining, we observed thatSCg6 Rspo3 knockdown cells showed increased G1 phase comparedto control cells, which suggests that reducing Rspo3 expressionaffects cell cycling. However, cell viability, analyzed by MTTand Trypan Blue assays was moderately or not significantly alteredby reducing Rspo3 levels. For the optimization of the in ovo assay,tumors from SCg6 spheroids were successfully grown on the chickchorioallantoic membrane (CAM), which constitutes an alternativetool to validate the results observed in vitro. Moreover, canine mammarybiopsies were correctly grafted onto de CAM, which betterrecapitulates physiological conditions and tumor heterogeneity. Finally,single-cell RNA sequencing datasets from oncologic patientswere processed and analyzed in order to explore cellular heterogeneityin basal-like tumors. Additionally, through measurement ofthe expression of Rspo3 and target genes of the Wnt pathway, itwas possible to evaluate the relevance of therapies that modulatethese genes. These results highlight the impact of the Wnt pathwayin the acquisition of tumorigenic characteristics of basal-type breastcancer cells. In addition, grafting of biopsies onto the CAM will allowfor in ovo testing of Wnt pathway inhibiting drugs, already availableat the laboratory, to evaluate the efficacy of this therapeutic strategyin vivo.