Abstract:
Human galectin-1 (hGal-1) is a soluble, secreted protein that non-covalently binds β-galactosides and contributes to cancer progression through both extracellular and intracellular mechanisms. In particular, evasion of antitumor immunity and growth suppressors, induction of angiogenesis, and increased invasiveness and metastatic potential of tumors have been linked to hGal-1 expression. Although targeting hGal-1 has been identified as a potential therapeutic approach, potent single-digit nanomolar small molecule inhibitors of hGal-1 that are highly selective for hGal-1 over human galectin-3 (hGal-3) are still lacking. We have discovered a highly potent and selective carbohydrate-based hGal-1 inhibitor, termed RuTDG, bearing a half-sandwich organoruthenium complex as a key structural fragment responsible for the high binding affinity. The goal of this project is to evaluate the RuTDG and compounds obtained by its structural modifications as antitumor agents using cellular assays and mouse models. First, RuTDG-derived inhibitors will be initially screened, including determination of in vitro affinity to human and murine galectin-1 and -3, solubility, solution stability, binding to plasma proteins, effects on cell viability and microsomal stability. The two best performing inhibitors will then be evaluated for cytostatic, antimigratory, anti-invasive and angiostatic properties in cell-based assays using the inhibitors alone or in combination with chemo- and radiotherapy. Cells with manipulated LGALS1 expression will then be used to confirm the specificity. In addition, the effect of the inhibitors on immune cells performance and cancer cell signaling will be evaluated using 2D and 3D cell models. The uptake of ruthenium by cells will also be determined. The molecular basis of the inhibition will be investigated by NMR spectrometry. The in vivo antitumor effects of the best inhibitors will then be evaluated in mouse xenografts and syngeneic models.