Mechanisms Involved in the Inhibition of Aurora Kinases in Adrenal Carcinoma

Author(s)

Kleiton Silva Borges

• Document type: Doctoral Thesis
• Press: Ribeirão Preto.
• Institution: Universidade de São Paulo (USP). Faculdade de Medicina de Ribeirão Preto (PCARP/BC)
• Defense date: 2014-05-09

Examining board members

Luiz Gonzaga Tone; Madson Queiroz de Almeida; Maria Sol Brassesco Annichini; Sonir Roberto Rauber Antonini; Mara Albonei Dudeque Pianovski

• Advisor: Luiz Gonzaga Tone

Abstract

Introduction: Pediatric adrenocortical tumors (ACT) are rare malignancies representing only 0.2 % of all pediatric cancers. Most cases are diagnosed in Brazil and are associated with TP53 p.R337H mutation. Surgery is the only effective treatment known for the ACT however this approach has a small impact on survival in advanced disease. The Aurora kinase family is comprised of three members (Aurora-A, -B and -C) which act at different phases of the cell cycle, such as chromosomes alignment, mitotic spindle formation and cytokinesis. Several studies have demonstrated altered expression of members of this family in various types of tumors and the functional inhibition of the aurora kinases have been considered as a potential approach to cancer treatment. Aim: On the basis of analysis of Aurora-A and Aurora-B gene expression in the samples from pediatric ACT, we investigated the effects of AMG 900, a pan-aurora kinase inhibitor, on proliferation, apoptosis rate, hormone synthesis and transcriptional profile of H295A cell line. Furthermore, we evaluated the effects of AMG 900 combined with different chemotherapeutic agents. Methods: The mRNA expression levels of Aurora-A and Aurora-B genes were analyzed in 60 children with ACT by RT-qPCR and immunohistochemistry. Cell proliferation was assessed by Giemsa staining and apoptosis was performed by flow cytometry. Drug combination analysis was made on the basis of Chou- Talalay method. Microarray experiments were carried out using the Agilent human microarray. Results: Aurora-A and Aurora-B overexpression was associated with advanced disease. Patients carrying the TP53 p.R337H mutation presented significantly higher expression values of Aurora-A. Treatment with AMG900 caused inhibition of proliferation, increased apoptosis and sensitized the cells to topoisomerase II inhibitors (doxorubicin and etoposide). Additionally, the AMG 900 led to decreased synthesis of hormones and modulated the expression of genes involved in this activity. Finally, Aurora kinases inhibition altered the expression of genes associated with G1 cell cycle phase regulation and affected the Notch signaling pathway target genes. Conclusion: These data suggest that Aurora kinase inhibition by AMG900 may be a new therapeutic approach to adrenocortical carcinoma treatment. (AU)

• FAPESP's process: 10/08699-5 - Mechanisms involved in the inhibition of aurora-kinases in adrenal carcinoma
• Grantee: Kleiton Silva Borges
• Support Opportunities: Scholarships in Brazil - Doctorate