Malignant gliomas are characterized by an intrinsic ability to invade diffusely throughout the normal brain tissue. This feature contributes mainly to the failure of existing therapies. Deregulation of small GTPases signaling, in particular Rac1 activity, plays a key role in the invasive phenotype of gliomas. Here we report the effect of ZINC69391, a specific Rac1 inhibitor developed by our group, on human glioma cell lines LN229 and U-87 MG. ZINC69391 is able to interfere with the interaction of Rac1 with Dock180, a relevant Rac1 activator in glioma invasion, and to reduce Rac1-GTP levels. The kinase Pak1, a downstream effector of Dock180–Rac1 signaling, was also downregulated upon ZINC69391 treatment. ZINC69391 reduced cell proliferation, arrested cells in G1 phase, and triggered apoptosis in glioma cells. Importantly, ZINC69391 dramatically affected cell migration and invasion in vitro, interfering with actin cytoskeleton dynamics. We also evaluated the effect of analog 1A-116, a compound derived from ZINC69391 structure. 1A-116 showed an improved antiproliferative and antiinvasive activity on glioma cells. These findings encourage further preclinical testing in clinically relevant animal models.
ObjectiveThe RHO family of GTPases, particularly RAC1, has been linked with hepatocarcinogenesis, suggesting that their inhibition might be a rational therapeutic approach. We aimed to identify and target deregulated RHO family members in human hepatocellular carcinoma (HCC).DesignWe studied expression deregulation, clinical prognosis and transcription programmes relevant to HCC using public datasets. The therapeutic potential of RAC1 inhibitors in HCC was study in vitro and in vivo. RNA-Seq analysis and their correlation with the three different HCC datasets were used to characterise the underlying mechanism on RAC1 inhibition. The therapeutic effect of RAC1 inhibition on liver fibrosis was evaluated.ResultsAmong the RHO family of GTPases we observed that RAC1 is upregulated, correlates with poor patient survival, and is strongly linked with a prooncogenic transcriptional programme. From a panel of novel RAC1 inhibitors studied, 1D-142 was able to induce apoptosis and cell cycle arrest in HCC cells, displaying a stronger effect in highly proliferative cells. Partial rescue of the RAC1-related oncogenic transcriptional programme was obtained on RAC1 inhibition by 1D-142 in HCC. Most importantly, the RAC1 inhibitor 1D-142 strongly reduce tumour growth and intrahepatic metastasis in HCC mice models. Additionally, 1D-142 decreases hepatic stellate cell activation and exerts an anti-fibrotic effect in vivo.ConclusionsThe bioinformatics analysis of the HCC datasets, allows identifying RAC1 as a new therapeutic target for HCC. The targeted inhibition of RAC1 by 1D-142 resulted in a potent antitumoural effect in highly proliferative HCC established in fibrotic livers.
The Rho GTPase Rac1 is involved in the control of cytoskeleton reorganization and other fundamental cellular functions. Aberrant activity of Rac1 and its regulators is common in human cancer. In particular, deregulated expression/activity of Rac GEFs, responsible for Rac1 activation, has been associated to a metastatic phenotype and drug resistance. Thus, the development of novel Rac1‐GEF interaction inhibitors is a promising strategy for finding new preclinical candidates. Here, we studied structure–activity relationships within a new family of N,N’‐disubstituted guanidine as Rac1 inhibitors. We found that compound 1D‐142, presents superior antiproliferative activity in human cancer cell lines and higher potency as Rac1‐GEF interaction inhibitor in vitro than parental compounds. In addition, 1D‐142 reduces Rac1‐mediated TNFα‐induced NF‐κB nuclear translocation during cell proliferation and migration in NSCLC. Notably, 1D‐142 allowed us to show for the first time the application of a Rac1 inhibitor in a lung cancer animal model.
<p>Rac1 (Ras-related C3 botulinum toxin substrate 1), is a member of the family of Rho GTPases involved in the dynamic control of cytoskeleton reorganization and other fundamental cellular functions including growth, motility and survival. Aberrant activity of Rac1 and its regulators is common in human cancer. In particular, deregulated expression/activity of Rac Guanine nucleotide Exchange Factors (GEFs), responsible for Rac activation, has been largely associated to a metastatic phenotype and drug resistance. Thus, the development of novel Rac1-GEF interaction inhibitors is a promising strategy for finding new preclinical candidates. In this work, we have studied structure-activity relationships within a new family of N,N’-disubstituted guanidine as Rac1-GEF protein-protein interaction inhibitors, starting from our first developed member 1A-116. We found that new analogue 1D-142, bearing a pyridine ring instead of benzene ring, presents improved antiproliferative activity in human cancer cell lines and higher potency as Rac1-GEF interaction inhibitor in vitro. In addition, 1D-142 reduces TNFα-induced NF-κB nuclear translocation, a mechanisms mediated by Rac1 during cell proliferation and migration in NSCLC. Notably, 1D-142 was used to show for the first time the application of a Rac1 inhibitor in a lung cancer animal model.<br></p>
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