The Rac Inhibitor EHop-016 Inhibits Mammary Tumor Growth and Metastasis in a Nude Mouse Model

Abstract

Metastatic disease still lacks effective treatments, and remains the primary cause of cancer mortality. Therefore, there is a critical need to develop better strategies to inhibit metastatic cancer. The Rho family GTPase Rac is an ideal target for anti-metastatic cancer therapy, because Rac is a key molecular switch that is activated by a myriad of cell surface receptors to promote cancer cell migration/invasion and survival. Previously, we reported the design and development of EHop-016, a small molecule compound, which inhibits Rac activity of metastatic cancer cells with an IC50 of 1 μM. EHop-016 also inhibits the activity of the Rac downstream effector p21-activated kinase (PAK), lamellipodia extension, and cell migration in metastatic cancer cells. Herein, we tested the efficacy of EHop-016 in a nude mouse model of experimental metastasis, where EHop-016 administration at 25 mg/kg body weight (BW) significantly reduced mammary fat pad tumor growth, metastasis, and angiogenesis. As quantified by UPLC MS/MS, EHop-016 was detectable in the plasma of nude mice at 17 to 23 ng/ml levels at 12 h following intraperitoneal (i.p.) administration of 10 to 25 mg/kg BW EHop-016. The EHop-016 mediated inhibition of angiogenesis In Vivo was confirmed by immunohistochemistry of excised tumors and by In Vitro tube formation assays of endothelial cells. Moreover, EHop-016 affected cell viability by down-regulating Akt and Jun kinase activities and c-Myc and Cyclin D expression, as well as increasing caspase 3/7 activities in metastatic cancer cells. In conclusion, EHop-016 has potential as an anticancer compound to block cancer progression via multiple Rac-directed mechanisms.

Integrin-α10 Dependency Identifies RAC and RICTOR as Therapeutic Targets in High-Grade Myxofibrosarcoma

“…Furthermore, EHop-016 revealed significant anti-tumor activity for both subcutaneous primary tumors and lung metastasis after tail vein injection. These results, together with reports that RAC inhibitors of this class have pre-clinical efficacy against several tumor types (38, 39), further support the idea of targeting the TRIO/RAC axis. EHop-016 seems particularly promising for further development, since in mice it has 26% to 40% oral bioavailability and linear pharmacokinetic profiles (40).…”

Direct Modulation of Small GTPase Activity and Function

“…Compound 32 significantly reduces tumor growth, metastasis,and angiogenesis in breast cancer mouse models. [118] Compared to 28,R ac1 inhibition can be achieved with a1 0-50-fold lower concentration of 32.…”

Minireview: Mouse Models of Rho GTPase Function in Mammary Gland Development, Tumorigenesis, and Metastasis

“…EHop-016, a derivative of the Rac1 inhibitor NSC23766, blocked MDA-MB-435 tumor growth and metastasis in nude mice xenografts (65). EHop-016 also inhibited interaction between Rac1 and the RhoGEF Vav guanine nucleotide exchange factor 1 (Vav1) and prevented activation of Rac1, Pak1 and v-akt murine thyoma viral oncogene homolog 1 (Akt1) in cells.…”