Effect of inhibition of the Wnt pathway in basal-like mammary tumor cells

PETRIZ OTAÑO, LUCÍA PAULA; FELCHER, CARLA MARÍA; MOSNA, MARÍA JIMENA; GARDE, FEDERICO JULIÁN; STINSON, MARCELO GABRIEL; DI BELLA, DANIELA JÉSICA; KORDON, EDITH CLAUDIA; CARCAGNO, ABEL LUIS

Mar del Plata

Congreso; Reunión Anual de Sociedades de Biociencias 2022; 2022

SAIC, SAI & FAIC, SAFIS

In 2020, breast cancer ranked first regarding cancer incidence and mortality worldwide. Basal-like tumors represent approximately 15-20% of all breast cancers and show aggressive behavior, with a high probability of recurrence and few specific therapies. Our aim was to study in vitro and in ovo the effects of knocking down R-spondin 3 (Rspo3), which (as demonstrated previously) enhances the canonical Wnt pathway in the SCg6 basal-like tumor cell line. Using flow cytometry assays with Propidium Iodide staining, we observed that SCg6 Rspo3 knockdown cells showed increased G1 phase compared to control cells, which suggests that reducing Rspo3 expression affects cell cycling. However, cell viability, analyzed by MTT and Trypan Blue assays was moderately or not significantly altered by reducing Rspo3 levels. For the optimization of the in ovo assay, tumors from SCg6 spheroids were successfully grown on the chick chorioallantoic membrane (CAM), which constitutes an alternative tool to validate the results observed in vitro. Moreover, canine mammary biopsies were correctly grafted onto de CAM, which better recapitulates physiological conditions and tumor heterogeneity. Finally, single-cell RNA sequencing datasets from oncologic patients were processed and analyzed in order to explore cellular heterogeneity in basal-like tumors. Additionally, through measurement of the expression of Rspo3 and target genes of the Wnt pathway, it was possible to evaluate the relevance of therapies that modulate these genes. These results highlight the impact of the Wnt pathway in the acquisition of tumorigenic characteristics of basal-type breast cancer cells. In addition, grafting of biopsies onto the CAM will allow for in ovo testing of Wnt pathway inhibiting drugs, already available at the laboratory, to evaluate the efficacy of this therapeutic strategy in vivo.