Poster S13 - Engineered Breast Cancer Models with Age-Mimetic ECM for Drug Screening

Introduction: Aging is one of the most significant risk factors for breast cancer. The influence of age-related cellular alterations on breast cancer development has been extensively explored in previous studies. Recently, the significance of the aging breast tumor microenvironment has gained growing attention. Despite the significant advances in breast cancer diagnosis and therapies, screenings for novel breast cancer therapies for patients from different age groups are limited by the lack of an aging-related breast cancer model. Extensive literature has demonstrated the changes in mechanical and chemical properties and collagen structure with aging. Age-related alterations in physical properties and glycation of mouse tail tendon collagen have implied the possibility of modeling the aging breast ECM with collagen from mouse tail tendon. Here, we isolated and characterized collagen extracted from young and aged mice tail tendon and constructed a 3D age-related breast cancer model for drug screening with FDA-approved drug library with over 700 drugs.

Materials and

Methods: Tails and breast tissues of young (2-6 months) and aged (20-23 months) mice were collected. Soluble type I collagen was isolated from the tail tendons for characterization and engineering 3D breast tissue models. Lectin staining was performed to characterize the glycation of collagen in young and aged mouse breast and tail tendon tissue sections. Circular Dichroism was performed to assess the secondary structure and melting point of the isolated collagen I. A solution containing collagen (3 mg/mL) and transglutaminase (100 mg/mL) was prepared to construct 3D breast tissue models. Total collagen assays were performed to assess the degradation of the hydrogel model. Cancerous and normal human mammary epithelial cells were seeded on or in the 3D aged breast models to evaluate migration and invasion, respectively. Tumor spheroids were prepared with the ultra-low attachment method and successfully embedded in the collagen gels to construct the 3D breast cancer model. 3D invasion assessment and drug screening were performed with the automated BioTek BioSpa Live Cell Analysis System and a Biomek i7 Liquid Handler coupled with CTG assays.

Results, Conclusions, and Discussions: Lectin staining confirmed higher level of glycation in collagen fibers in both native breast ECM and tail tendon of aged mice. Degradation studies confirmed the stability of the 3D model within 7-day incubation. Epithelial cells showed significantly increased migration and invasion behavior in/on the 3D aged breast model, in accordance with our findings in the aged breast ECM sections. mRNA qPCR analysis of cancerous and normal epithelial cells and mammary fibroblasts encapsulated in the 3D aged breast tissue models all demonstrated an increased expression in SERPINE1, an established aging marker. These results have indicated the potential of the established 3D age-related breast cancer model for novel drug screening. Tumor spheroids were successfully embedded in the gels to construct 3D age-related breast cancer models. Tumor spheroids embedded in the aging breast cancer models also demonstrated higher 3D invasion ability over the period of 7 days monitor. Tumor spheroids within the aged and young breast cancer models presented different drug responses to selected drug treatments. Within the screened FDA-approved drug library, we identified 37 drug targets that are effective in inhibiting breast cancer progression in both age groups with 33 only effective in the young models. In this study, we isolated and characterized soluble collagen I extracted from young and aged mice tail tendon and for the first time in literature utilized the extracted biomaterials to construct a stable 3D age-related breast cancer model for aging-related studies and high-throughput novel drug screening.

Acknowledgements (Optional): This work is supported by The Interdisciplinary Interface Training Program (IITP) Grant, made possible by the Walther Cancer Foundation.