3D Breast Cancer Spheroids Reveal Architecture-Dependent HER2 Expression and Signaling

Area of Science:

• Oncology
• Biotechnology
• Cell Biology

Background:

• Three-dimensional (3D) cell culture models offer a more physiologically relevant alternative to traditional 2D monolayers for studying cancer biology.
• HER2-positive breast cancer (BCa) is a significant subtype that benefits from targeted therapies, but predictive in vitro models are limited.

Purpose of the Study:

• To generate and compare 3D spheroids from two HER2-positive BCa cell lines (SKBR3 and BT474).
• To investigate the influence of 3D architecture on HER2 distribution, intracellular signaling, and cellular organization within these spheroids.

Main Methods:

• Reproducible generation and 4-day culture of SKBR3 and BT474 spheroids.
• Assessment of cell viability, HER2 distribution (confocal microscopy, cryosections), protein expression/phosphorylation (Western blotting), epithelial markers (immunofluorescence), and ultrastructure (transmission electron microscopy - TEM).

Main Results:

• SKBR3 spheroids were loose and heterogeneous; BT474 spheroids were compact and spherical.
• HER2 localized to the membrane with signal decrease towards the spheroid core, more pronounced in BT474 spheroids.
• Divergent HER2 expression and AKT phosphorylation observed: SKBR3 showed increased HER2/reduced pAKT; BT474 showed reduced HER2/pAKT. Differences in epithelial markers and ultrastructure correlated with spheroid compactness.

Conclusions:

• 3D architecture significantly impacts HER2 distribution, signaling, and organization in HER2-positive BCa spheroids.
• This 3D model serves as a robust platform for studying architecture-dependent processes.
• Potential applications include drug response evaluation, receptor trafficking studies, and targeted therapy assessment.