Diverse breast adipose stromal cell biology in women at high risk for developing breast cancer

Abstract Purpose: Adipose tissue constitutes a significant volume of the breast. However its influence on breast cancer initiation remains poorly understood. Breast adipose stromal cells (breast ASCs), essential progenitors of breast fat tissue, are abundant in breast adipose tissue. We studied the biology of primary human bASCs and their contribution to the tumor microenvironment.Methods: We generated a bASC cell repository from women undergoing prophylactic or therapeutic mastectomies (n=6 breast cancer patients; n=2 high risk patients). bASCs were isolated from the stromal vascular fraction of breast adipose tissue. Senescence was measured in bASCs using the senescence-associated beta-galactosidase detection kit. Senescence-associated-cytokines and chemokines in conditioned media collected from bASCs were measured by ELISA. The ability of bASCs to support cytokine signaling was determined by immunoblotting. Adipogenic potential of bASCs was determined by AdipoRed staining.Results: bASCs from 63% (5/8) of women in our cohort scored positive for senescence, with only some secreting senescence-associated cytokines (IL-6; TGF-beta) and chemokines (IL-8). Only in select cases was bASC secretion of cytokine associated with their ability to support cytokine-specific signaling pathways (e.g. TGFb/Smad2 signaling). bASCs from 38% (3/8) of these women exhibited an adipogenesis defect, and 2/3 (67%) also scored positive for senescence.Conclusion: bASC biology shows notable biologic variability in women undergoing prophylactic or therapeutic mastectomies, with some exhibiting a senescent phenotype, some exhibiting an adipogenesis defect, and some supporting TGFb or IL-6 signaling. Our results establish an important foundation for larger studies examining the impact of aberrant bASC biologies on breast cancer risk.