Mechanotransduction regulates adipose estrogen output and its impact on tumor cell growth

Adipose stromal cells (ASCs) are the primary source of local estrogens in adipose tissue, aberrant production of which promotes estrogen receptor-positive (ER+) breast cancer. Here we show that extracellular matrix (ECM) rigidity and cell contractility are two opposing determinants for estrogen output of ASCs. Using synthetic ECMs and elastomeric micropost arrays with tunable rigidity, we find that increasing matrix compliance induces transcription of aromatase, a rate-limiting enzyme in estrogen biosynthesis. This mechanical cue is transduced sequentially by Discoidin Domain Receptor 1 (DDR1), c-Jun N-terminal kinase 1 (JNK1), and phosphorylated JunB, which binds to and activates two breast cancer-associated aromatase promoters. In contrast, elevated cell contractility due to actin stress fiber formation dampens aromatase transcription. Mechanically stimulated stromal estrogen production enhances estrogen-dependent transcription in ER+ tumor cells and promotes their growth. This novel mechanotransduction pathway underlies communications between ECM, stromal hormone output, and cancer cell growth within the same microenvironment. Total RNA was isolated from primary adipose stromal cells after 2d culture or 3d Collagen gel for 21 hours. Triplicates for each conditioned were analyzed