Spheroids of HER2-Positive Breast Adenocarcinoma for Studying Anticancer Immunotoxins In Vitro

Abstract

Tumor response to therapeutic treatment is largely determined by its heterogeneity and the presence of intercellular junctions, hindering the penetration of large molecules deep into the three-dimensional structure of the tumor. In that context, 3D in vitro tumor models such as cancer cell spheroids are becoming increasingly popular. We obtained spheroids of human breast adenocarcinoma SKBR-3 overexpressing the HER2 cancer marker. The toxicity of HER2-targeted immunotoxin 4D5scFv-PE40 against spheroids was shown to be several orders of magnitude lower compared to a monolayer cell culture. The significant difference in the severity of the immunotoxin effect can be explained by the fact that it ineffectively penetrates the spheroid and predominantly influences the cells of the outer layers. The resulting tumor spheroid model can be used in development of drugs for targeted therapy as well as to study ways to improve the efficiency of anticancer agents by targeting cell–cell contacts.

Synthetic Tuning of Domain Stoichiometry in Nanobody–Enzyme Megamolecules

“…35 While BT-474 was similarly sensitive to 5-FU treatment in adherent and spheroid culture, BT-474 clone 5 was more resistant to 5-FU treatment in spheroid culture (Figure S7 and Table 1), an effect observed in previous studies. 36,37 To enable comparison between cell lines, all remaining experiments used a concentration of 5-FC set to ten times the 5-FU IC 50 , unless otherwise noted.…”