In Vitro: LW6 affects the stability of the HIF-1α protein. LW6 promotes the degradation of wild type HIF-1α, but not of a DM-HIF-1α with modifications of P402A and P564A, at hydroxylation sites in the oxygen-dependent degradation domain. LW6 induces the expression of von Hippel-Lindau (VHL), which interacts with prolyl-hydroxylated HIF-1α for proteasomal degradation. In the presence of LW6, knockdown of VHL does not abolish HIF-1α protein accumulation, indicating that LW6 degraded HIF-1α via regulation of VHL expression. In MDCKII-BCRP cells overexpressing BCRP, LW6 enhances significantly the cellular accumulation of mitoxantrone, a BCRP substrate. LW6 also down-regulates BCRP expression at concentrations of 0.1-10 µM. LW6 inhibits the expression of HIF 1α induced by hypoxia in A549 cells at 20 µM, independently of the von Hippel Lindau protein. LW6 induces hypoxia selective apoptosis together with a reduction in the mitochondrial membrane potential.
In Vivo: In mice carrying xenografts of human colon cancer HCT116 cells, LW6 demonstrates strong anti-tumor efficacy in vivo and causes a decrease in HIF-1α expression in frozen-tissue immunohistochemical staining.