MET is a receptor tyrosine kinase known to be associated with cancer development and progression. Dysregulations of MET expression and/or signaling have been reported in breast cancer patients and determined to be associated with inferior outcomes rendering MET an appealing target for therapeutic interventions. Crizotinib is a multi-targeted

small-molecule kinase inhibitor for MET, ALK, and ROS1 kinases. In this study, the anti- proliferative, cytotoxic, anti-migratory, and anti-invasive effects of crizotinib have been

evaluated in breast cancer cells in vitro. Cell viability was assessed by 3-(4,5-dimethyl-2- thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) colorimetric assay. In vitro wound-

healing assay was used to examine the effect of crizotinib on breast cancer cell migration. Anti-invasive effect of crizotinib treatment in MDA-MB-231 breast cancer cells was measured using Trevigen Cultrex® BME Cell Invasion Assay. The expressions of Ki-67, MET, and phospho-MET receptors were characterized using immunofluorescence staining. Results showed that crizotinib has significant anti-proliferative activity on all mammary tumor cells with IC50 values of 5.16, 1.5, and 3.85 μM in MDA-MB-231, MCF- 7, and SK-BR-3 cells, respectively. Crizotinib induced cytotoxic effects in all breast cancer cells examined after acute exposure in culture. Combined treatment of small dose of crizotinib with the chemotherapeutic agent paclitaxel or doxorubicin exhibited a highly synergistic inhibition of growth of MDA-MB-231 and MCF-7 cells with combination index values of less than 1. However, no significant effect was observed for the combined treatment of crizotinib with chemotherapy in SK-BR-3 cells. Treatment with crizotinib demonstrated a remarkable reduction in the total levels of the proliferation marker Ki-67 protein in all tested cell lines. Crizotinib inhibited migration and invasion of MDA-MB-231 cells in a dose-dependent fashion. Crizotinib reduced MET receptor activation in MDA-MB-231 cells when treated at effective concentrations. In conclusion, crizotinib suppressed proliferation, migration, and invasion of breast cancer cells in vitro. The results of this study demonstrated that combined treatment of crizotinib with chemotherapeutic agents resulted in a synergistic growth inhibition of specific breast cancer cell lines. Combination treatment of chemotherapy with novel targeted therapy could be a promising approach to overcome the limitations of conventional chemotherapeutic regimens in breast cancer management.

Citation Format: Nehad M. Ayoub, Kamal M. Al-Shami, Mohammad A. Alqudah, Nizar M. Mhaidat. Crizotinib inhibits growth, migration, and invasion of breast cancer cells in vitro and synergizes with chemotherapeutic agents [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2937.