Figure 4.

Effect of the SMI-Sap and SMI(AF)-Sap conjugates on cell viability and proliferation. SMI-Sap conjugate mediates cellular toxicity to M21 cells at a subnanomolar IC50, but not to M21-L cells (A and B). SMI 1 and Sap also show minimum toxicity to M21 cells at 20nM concentration. SMI-Sap and SMI(AF)-Sap conjugates mediate strong toxicity (sub-nanomolar IC50) to M21 cells (C) but not to M21-L cells. SMI-Sap and SMI(AF)-Sap conjugates are also active against MDA-MB-435 cell variants 435 β3- in which the β3 integrin subunit gene had been knocked down, as well as to 435 ScrB in which β3 integrin expression had been restored by transduction with the β3 wild type gene (E, F). To measure effects of the compounds and conjugates on tumor cell viability and proliferation, 5×10³⁴ cells were plated into 24 well plates and incubated with or without compounds and conjugates at various concentration. After 72 hrs, cells were harvested and counted. Live cells were identified and counted based on trypan blue exclusion. Cell-survival assay was performed once, and there were three replicates.