Remodeling of tannic acid crosslinked collagen type I induces apoptosis in ER+ breast cancer cells.

BACKGROUND The naturally-occurring phytochemical tannic acid (TA) has anticancer properties. We have demonstrated that estrogen receptor-positive (ER+) breast cancer cells are more sensitive to effects of TA than triple-negative breast cancer cells and normal breast epithelial cells. In the present study, cells were grown on TA-crosslinked collagen beads. Growing cells remodel collagen and release TA, which affects attached cells. MATERIALS AND METHODS The ER+ breast cancer cell line MCF7 and the normal breast epithelial cell line MCF10A were grown on TA-crosslinked collagen beads in roller bottles. Concentrations of TA in conditioned media were determined. Induced apoptosis was imaged and quantified. Caspase gene expression was calculated by real-time polymerase chain reaction (PCR). RESULTS Both cell lines attached and grew on TA-crosslinked collagen beads where they remodeled collagen and released TA into surrounding medium. Released TA induced caspase-mediated apoptosis. CONCLUSION TA induced apoptosis in a concentration-dependent manner, with ER+ MCF7 cells displaying more sensitivity to effects of TA.