LAUSR

Simple Summary The most aggressive subtype of breast cancer, triple-negative breast cancer, is characterized by an excessive accumulation of hyaluronan in the cancer and its peritumoral stroma, which has been linked to poor prognosis of the patients. Inhibitors of hyaluronan synthesis would thus have a potential clinical value. We have identified the thymidine analog 5′-Deoxy-5′-(1,3-Diphenyl-2-Imidazolidinyl)-Thymidine (DDIT) as a new non-toxic inhibitor of hyaluronan synthesis. DDIT is more potent than the available inhibitor 4-Methylumbelliferone (4-MU), and significantly suppressed the aggressiveness of triple-negative breast cancer cells grown in tissue culture. Abstract Breast cancer is a common cancer in women. Breast cancer cells synthesize large amounts of hyaluronan to assist their proliferation, survival, migration and invasion. Accumulation of hyaluronan and overexpression of its receptor CD44 and hyaluronidase TMEM2 in breast tumors correlate with tumor progression and reduced overall survival of patients. Currently, the only known small molecule inhibitor of hyaluronan synthesis is 4-methyl-umbelliferone (4-MU). Due to the importance of hyaluronan for breast cancer progression, our aim was to identify new, potent and chemically distinct inhibitors of its synthesis. Here, we report a new small molecule inhibitor of hyaluronan synthesis, the thymidine analog 5′-Deoxy-5′-(1,3-Diphenyl-2-Imidazolidinyl)-Thymidine (DDIT). This compound is more potent than 4-MU and displays significant anti-tumorigenic properties. Specifically, DDIT inhibits breast cancer cell proliferation, migration, invasion and cancer stem cell self-renewal by suppressing HAS-synthesized hyaluronan. DDIT appears as a promising lead compound for the development of inhibitors of hyaluronan synthesis with potential usefulness in breast cancer treatment.