Design, synthesis, and biological evaluation of novel SN38-sulfonamide conjugates as Topo I/CA IX dual inhibitors inducing ferroptosis in colorectal cancer

Abstract

A series of novel SN38-sulfonamide conjugates were designed and synthesized as carbonic anhydrase IX (CA IX) and topoisomerase I (Topo I) dual inhibitors for colorectal cancer therapy. Structure-activity relationship analysis revealed that the length of alkyl linker critically influenced anticancer potency. Among them, compound 4f, featuring a six-atom linker, exhibited remarkable anticolorectal cancer potency and lower cytotoxicity against normal HK-2 cells compared to SN38. Moreover, compound 4f exhibited superior antitumor activities against colorectal cancer cells under hypoxia than that of normoxia conditions. Mechanistic investigations revealed that 4f potently inhibited CA IX and concurrently inhibited Topo I activity, leading to concentration-dependent DNA damage, as evidenced by comet tail formation and γ-H2AX upregulation. These effects triggered the intrinsic apoptotic pathway, characterized by increased Bax/Bcl-2 ratio, activation of cleaved caspase-3, while significantly suppressing cancer cell migration and invasion, mitochondrial dysfunction, and caspase-dependent apoptosis. Additionally, 4f induced mitochondrial dysfunction via ROS accumulation and loss of mitochondrial membrane potential. Notably, 4f also promoted ferroptosis through modulation of the CA IX/xCT/GPX4 axis and activation of the NCOA4 pathway. Together, this study establishes 4f as a potential CRC therapy agent for further development.