The antiangiogenic effects of polyisoprenylated cysteinyl amide inhibitors in HUVEC, chick embryo and zebrafish is dependent on the polyisoprenyl moiety

Abstract

Angiogenesis is essential for solid tumor growth, therapeutic resistance and metastasis, the latest accounting for 90% of cancer deaths. Although angiogenesis is essential for the malignant transformations in solid tumors and therefore is an attractive target, few drugs are available that block tumor angiogenesis. The focus has been to block signaling by receptor tyrosine kinases (RTKs), such as for vascular endothelial growth factor (VEGF), whose activation abrogate apoptosis and promote angiogenesis. The polyisoprenylated cysteinyl amide inhibitors (PCAIs) were designed to modulate aberrant polyisoprenylated small G-proteins such as mutant Ras whose constitutive activation promotes RTKs signaling. Since polyisoprenylation is essential for protein-protein interactions and functions of G-proteins, we hypothesized that the PCAIs would disrupt the monomeric G-protein signaling thereby effectively inhibiting angiogenesis. In this study we determined the effects of PCAIs on human umbilical vein endothelial cells (HUVEC) tube formation, cell viability, cell migration and invasion as well as in vivo using the chick chorioallantoic membrane (CAM) and zebrafish models. At sub- to low micromolar concentrations, the PCAIs inhibit the native and VEGF-stimulated cell migration and invasion as well as tube formation and angiogenesis in CAM and zebrafish embryos. The concentrations that block the angiogenic processes were lower than those that induce cell death. Since angiogenesis is essential for tumor growth but otherwise limited to wound healing, feeding fat cells and uterine wall repair in adults, it is conceivable that these compounds can be developed into safer therapeutics for cancers and retinal neovascularization that leads to loss of vision.

Polyisoprenylated cysteinyl amide inhibitors disrupt actin cytoskeleton organization, induce cell rounding and block migration of non-small cell lung cancer

“…In our quest to better understand the role of PCAIs in cell migration, we examined the time-dependent changes in size of H1299 cells. In addition to using the PCAIs in these assays, we synthesized an analog of the PCAIs, NSL-100 in which the farnesyl moiety is replaced with an ethyl group [ 26 ]. Using live cell imaging microscopy, we captured DIC images of cells at different time points after exposure to 5 μM NSL-BA-040 or 5 μM of NSL-100 (Figure 4A ).…”

“…In this study we describe for the first time, the role of PCAIs, a novel class of compounds that were synthesized to mimic the posttranslational modifications in polyisoprenylated small monomeric G-proteins, in modulating the F-actin cytoskeleton to suppress lung cancer cell migration and invasion. In a recent report [ 26 ], we demonstrated that the PCAIs possess anti-angiogenic effects. We report that the PCAIs (1) suppress 2D and 3D NSCLC migration and invasion; (2) induce morphological changes promoting cell rounding; (3) disrupt F-actin organization and diminish filopodia density and (4) diminish Rac1, Cdc42 and RhoA protein levels but do not alter RhoA localization to compromise their functions in cytoskeletal organization.…”

“…The PCAIs, NSL-BA-040, NSL-BA055, and their non-farnesylated analog NSL-100 were used for treatment. The chemical structures are as previously described [ 26 ].…”

“…These results point to the potential of the PCAIs to be effective therapies in suppressing metastasis at concentrations that are not cytotoxic thereby eliminating the potential toxic side effects. The PCAIs-induced effects against cell migration and invasion, coupled with the aforementioned potent effects against angiogenesis [ 26 ] imply that metastasis is likely to be severely limited in the presence of the PCAIs.…”

“…The benefits of pharmacologically controlling the F-actin cytoskeleton in the treatment of tumor metastasis are significant as cytoskeletal remodeling is involved in multiple cellular processes and events such as in EMT that drive the transformed phenotype. Although more work is needed to fully decipher the precise mechanism by which the PCAIs elicit their effects, nonetheless our previous findings that the PCAIs attenuate angiogenesis [ 26 ] and current observations on cell migration and invasion make them a desirable candidate to be developed for the targeted treatment of lung cancers with hyperactive signaling pathways involving polyisoprenylated proteins. We are currently conducting structural and biochemical assays to identify the molecular target(s) to which the PCAIs bind to in order to elicit their F-actin modulating effects.…”