Structure-activity relationship and molecular mechanisms of ethyl 2-amino-4-(2-ethoxy-2-oxoethyl)-6-phenyl-4H-chromene-3-carboxylate (sHA 14-1) and its analogues

Rapid development of multiple drug resistance against current therapies is a major barrier in the treatment of cancer. Therefore, anticancer agents that can overcome acquired drug resistance in cancer cells are of great importance. Previously, we have demonstrated that ethyl 2-amino-4-(2-ethoxy-2-oxoethyl)-6- phenyl-4H-chromene-3-carboxylate (5a, sHA 14-1), a stable analogue of ethyl 2-amino-6-bromo-4-(1-cyano-2-ethoxy-2-oxoethyl)-4H-chromene-3-carboxylate (6, HA 14-1), mitigates drug resistance and synergizes with a variety of cancer therapies in leukemia cells. Structure-activity relationship (SAR) studies of 5a guided the development of ethyl 2-amino-6-(3′,5′-dimethoxyphenyl)- 4-(2-ethoxy-2-oxoethyl)-4H-chromene-3-carboxylate (5q, CXL017), a compound with low micromolar cytotoxicity against a wide-range of hematologic and solid tumor cells. More excitingly, our studies of 5q in camptothecin (CCRF-CEM/C2) and mitoxantrone (HL-60/MX2) resistant cancer cells highlight its ability to selectively kill drug-resistant cells over parent cancer cells. 5q inhibits tumor cell growth through the induction of apoptosis, with detailed mechanism of its selectivity toward drug-resistant cancer cells under investigation. These results suggest that 5q is a promising candidate for treatment of cancers with multiple drug resistance.