Development of Breast Cancer Spheroids to Evaluate Cytotoxic Response to an Anticancer Peptide.

Breast cancer (BC) is the most commonly diagnosed cancer in women and one of the most common causes of cancer-related deaths. Despite intense research efforts, BC treatment still remains challenging. Improved drug development strategies are needed for impactful benefit to patients. Current preclinical studies rely mostly on cell-based screenings, using two-dimensional (2D) cell monolayers that do not mimic in vivo tumors properly. Herein, we explored the development and characterization of three-dimensional (3D) models, named spheroids, of the most aggressive BC subtypes (triple-negative breast cancer-TNBC; and human-epidermal growth receptor-2-HER2+), using the liquid overlay technique with several selected cell lines. In these cell line-derived spheroids, we studied cell density, proliferation, ultrastructure, apoptosis, reactive oxygen species (ROS) production, and cell permeabilization (live/dead). The results showed a formation of compact and homogeneous spheroids on day 7 after seeding 2000 cells/well for MDA-MB-231 and 5000 cells/well for BT-20 and BT-474. Next, we compared the efficacy of a model anticancer peptide (ACP) in cell monolayers and spheroids. Overall, the results demonstrated spheroids to be less sensitive to treatment than cell monolayers, revealing the need for more robust models in drug development.

Influence of adhesive and thermal cycling on the bond strength of ceramic brackets to dental ceramic

Aim: This in vitro study investigated the effect of the application of an adhesive, silane and thermal cycling (TC) on the shear bond strength (SBS) of ceramic brackets to feldspathic ceramic. Methods: 16 cylinders of feldspathic ceramic were etched with hydrofluoric acid and divided into four groups (n=4): G1 - silane, without TC; G2 ­ silane, with TC; G3 - adhesive, without TC; G4 - adhesive, with TC. One layer of silane was applied on the surface of cylinders in G1 and G2 e one layer of photo-activated adhesive Single Bond Universal was used in G3 and G4. Ceramic brackets were bonded using Transbond XT. The SBS data were subjected to two-way ANOVA and Tukey's post hoc test (α=0.05). The Adhesive Remnant Index (ARI) was evaluated at 40× magnification. Results: Silane was more effective than adhesive on the SBS of the brackets to ceramic (p<0.05). TC decreased significantly the SBS values compared with the groups without TC (p<0.05). The ARI results showed predominance of score 0. Conclusions: Groups with silane showed higher SBS than groups with adhesive. TC influence significantly on the bond strength. Regarding ARI, score 0 predominated in all groups (Au)