Abstract
The naked mole rat (nmr) is cancer resistant due to the abundant production of extremely high-molecular-weight hyaluronan (EHMW-HA). However, whether EHMW-HA has similar anti-cancer effects in mice and humans remains to be determined. The present study used breast cancer cells to clarify the effect of EHMW-HA on breast cancer. First, the overexpression of nmrHas2 in 4T1 and BT549 cell lines in both two-dimensional (2D) and three-dimensional (3D) models to mimic tumor microenvironment was established. The 4T1/BT549-nmrHas2 cells could secrete EHMW-HA (with a molecular weight of up to 6 MDa), which was similar to that found in the naked mole rat. Second, EHMW-HA altering tumor microenvironment in both 2D monolayers and 3D spheroids significantly enhanced apoptosis, inhibiting the proliferation of 4T1 and BT549 cells. The prominent anticancer effects of EHMW-HA on the cancer-cell apoptosis phenotype were further confirmed by inhibiting tumor formation in nude mice. Finally, EHMW-HA significantly induced higher p53 protein expression, which enhanced pro-apoptotic proteins p21 and Bax in breast cancer cells; this is in contrast with the triggering of hypersensitivity of the naked mole rat cells to early contact inhibition (ECI). These results have important implications for the design of therapeutic approaches based on the application of EHMW-HA.