RESUMO
Dysregulation of the tightly controlled protein phosphorylation networks that govern cellular behavior causes cancer. The membrane-associated, intracellular protein tyrosine phosphatase PTP4A3 is overexpressed in human colorectal cancer and contributes to cell migration and invasion. To interrogate further the role of PTP4A3 in colorectal cancer cell migration and invasion, we deleted the Ptp4a3 gene from murine colorectal tumor cells. The resulting PTP4A3-/- cells exhibited impaired colony formation, spheroid formation, migration, and adherence compared with the paired PTP4A3fl/fl cells. We replicated these phenotypic changes using the new small-molecule, allosteric PTP4A3 inhibitor JMS-053. A related structure, JMS-038, which lacked phosphatase inhibition, displayed no cellular activity. Reduction in cell viability and colony formation by JMS-053 occurred in both mouse and human colorectal cell lines and required PTP4A3 expression. Ptp4a3 deletion increased the expression of extracellular matrix (ECM) and adhesion genes, including the tumor suppressor Emilin 1. JMS-053 also increased Emilin 1 gene expression. Moreover, The Cancer Genome Atlas genomic database revealed human colorectal tumors with high Ptp4a3 expression had low Emilin 1 expression. These chemical and biologic reagents reveal a previously unknown communication between the intracellular PTP4A3 phosphatase and the ECM and support efforts to pharmacologically target PTP4A3.-McQueeney, K. E., Salamoun, J. M., Ahn J. G., Pekic, P., Blanco, I. K., Struckman, H. L., Sharlow, E. R., Wipf, P., Lazo, J. S. A chemical genetics approach identifies PTP4A3 as a regulator of colon cancer cell adhesion.
Assuntos
Neoplasias do Colo/metabolismo , Matriz Extracelular/metabolismo , Proteínas Imediatamente Precoces/metabolismo , Proteínas de Neoplasias/metabolismo , Proteínas Tirosina Fosfatases/metabolismo , Animais , Adesão Celular/genética , Linhagem Celular Tumoral , Neoplasias do Colo/genética , Matriz Extracelular/genética , Matriz Extracelular/patologia , Proteínas Imediatamente Precoces/antagonistas & inibidores , Proteínas Imediatamente Precoces/genética , Camundongos , Camundongos Knockout , Proteínas de Neoplasias/antagonistas & inibidores , Proteínas de Neoplasias/genética , Proteínas Tirosina Fosfatases/antagonistas & inibidores , Proteínas Tirosina Fosfatases/genéticaRESUMO
Overexpression of protein tyrosine phosphatase PTP4A oncoproteins is common in many human cancers and is associated with poor patient prognosis and survival. We observed elevated levels of PTP4A3 phosphatase in 79% of human ovarian tumor samples, with significant overexpression in tumor endothelium and pericytes. Furthermore, PTP4A phosphatases appear to regulate several key malignant processes, such as invasion, migration, and angiogenesis, suggesting a pivotal regulatory role in cancer and endothelial signaling pathways. While phosphatases are attractive therapeutic targets, they have been poorly investigated because of a lack of potent and selective chemical probes. In this study, we disclose that a potent, selective, reversible, and noncompetitive PTP4A inhibitor, JMS-053, markedly enhanced microvascular barrier function after exposure of endothelial cells to vascular endothelial growth factor or lipopolysaccharide. JMS-053 also blocked the concomitant increase in RhoA activation and loss of Rac1. In human ovarian cancer cells, JMS-053 impeded migration, disrupted spheroid growth, and decreased RhoA activity. Importantly, JMS-053 displayed anticancer activity in a murine xenograft model of drug resistant human ovarian cancer. These data demonstrate that PTP4A phosphatases can be targeted in both endothelial and ovarian cancer cells, and confirm that RhoA signaling cascades are regulated by the PTP4A family.
