Targeting Cdc42 with the small molecule drug AZA197 suppresses primary colon cancer growth and prolongs survival in a preclinical mouse xenograft model by downregulation of PAK1 activity

Abstract

BackgroundRho GTPases play important roles in cytoskeleton organization, cell cycle progression and are key regulators of tumor progression. Strategies to modulate increased Rho GTPase activities during cancer progression could have therapeutic potential.MethodsWe report here the characterization of a Cdc42-selective small-molecule inhibitor AZA197 for the treatment of colon cancer that was developed based on structural information known from previously developed compounds affecting Rho GTPase activation. We investigated the effects of AZA197 treatment on RhoA, Rac1 and Cdc42 activities and associated molecular mechanisms in colon cancer cells in vitro. Therapeutic effects of AZA197 were examined in vivo using a xenograft mouse model of SW620 human colon cancer cells. After treatment, tumors were excised and processed for Ki-67 staining, TUNEL assays and Western blotting to evaluate proliferative and apoptotic effects induced by AZA197.ResultsIn SW620 and HT-29 human colon cancer cells, AZA197 demonstrated selectivity for Cdc42 without inhibition of Rac1 or RhoA GTPases from the same family. AZA197 suppressed colon cancer cell proliferation, cell migration and invasion and increased apoptosis associated with down-regulation of the PAK1 and ERK signaling pathways in vitro. Furthermore, systemic AZA197 treatment reduced tumor growth in vivo and significantly increased mouse survival in SW620 tumor xenografts. Ki-67 staining and tissue TUNEL assays showed that both inhibition of cell proliferation and induction of apoptosis associated with reduced PAK/ERK activation contributed to the AZA197-induced therapeutic effects in vivo.ConclusionsThese data indicate the therapeutic potential of the small-molecule inhibitor AZA197 based on targeting Cdc42 GTPase activity to modulate colorectal cancer growth.

Redundant and nonredundant roles for Cdc42 and Rac1 in lymphomas developed in NPM-ALK transgenic mice

“…2,27 Our data indicate that a simultaneous inhibition of both Cdc42 and Rac1 would likely have a more profound effect on lymphoma growth and dissemination. As dual Cdc42/Rac1 inhibitors have been recently developed and are currently tested in preclinical mouse models, 28 this approach could represent a potential additional therapeutic strategy for NPM-ALK lymphoma.…”

Two Small Molecules, ZCL278 and AZA197 Show Promise in Influencing Protein Interactions Involving the Ras-Related Protein Cell division cycle 42 [Cdc42] to Modulate Its Oncogenic Potential

“…In vitro studies showed that the small molecule inhibited a Cdc42-GEF interaction involving Dbs, a Dbl guanine nuc- Cdc42 over-activity. Moreover, Cdc42 signaling pathways involving binding to the downstream effector PAK1, and its involvement in ERK pathway were down regulated by AZA197 [13]. These studies highlighted the potential influence that the small molecule AZA197 could have on a PPI that leads to Cdc42-stimulated hyperactivity.…”

“…Results from the experiments of Zins et al showed that AZA197 could target GTP-bound Cdc42 and inhibit Cdc42-stimulated hyperactivity, as characterized by the suppression of proliferation of SW620 colon cancer cells, a reduction of the migration and invasion potential of these cells, and the inhibition of cell growth in vivo [13]. In vitro studies showed that the small molecule inhibited a Cdc42-GEF interaction involving Dbs, a Dbl guanine nuc- Cdc42 over-activity.…”

“…rimidine-2,4-diamine, known as AZA197 (Figure 3(b)), influenced Cdc42-stimulated function [13]. Results from the experiments of Zins et al showed that AZA197 could target GTP-bound Cdc42 and inhibit Cdc42-stimulated hyperactivity, as characterized by the suppression of proliferation of SW620 colon cancer cells, a reduction of the migration and invasion potential of these cells, and the inhibition of cell growth in vivo [13].…”

“…These studies highlighted the potential influence that the small molecule AZA197 could have on a PPI that leads to Cdc42-stimulated hyperactivity. However, further development will be needed in the use of AZA197 because, due to toxicity, only low μM concentrations of the small molecule could be used [13]. Zins et al, also pointed out that, at concentrations > 20 μM, this molecule destroyed the plasma membrane of SW620 and HT-29 colon cancer cells, as well as S3T3 fibroblast cells.…”