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Study of the functional role of PAR-4 and SPARC in breast cancer cell survival and chemosensitivity

Grant number: 10/16543-5
Support Opportunities:Regular Research Grants
Duration: April 01, 2011 - March 31, 2013
Field of knowledge:Biological Sciences - Biochemistry - Molecular Biology
Principal Investigator:Maria Aparecida Nagai
Grantee:Maria Aparecida Nagai
Host Institution: Faculdade de Medicina (FM). Universidade de São Paulo (USP). São Paulo , SP, Brazil
Associated researchers:Flavia Regina Rotea Mangone ; José César Rosa ; Rosimeire Aparecida Roela ; Simone Aparecida de Bessa Garcia


Breast cancer is considered a heterogeneous disease-differing by individual, with varied clinical behavior. Breast cancer is the most commonly diagnosed neoplasm and the major source of morbidity and mortality among women worldwide. In Brazil, breast cancer is one of the most frequent malignancies in women and the leading cause of mortality. Data from the Ministry of Health estimates the occurrence of 49.240 new cases of breast cancer in 2010, representing an important health problem (INCA, Ministério da Saúde, 2010).In spite of the advances in our understanding of the molecular basis of breast cancer, chemotherapy remains the only choice of treatment available for patients with advanced breast tumors. A major clinical problem associated with fatality of advanced breast cancer patients is the intrinsic or acquired resistance to chemotherapy that leads to a high recurrence rate and reduced overall survival. To date, there are no clinically useful predictive markers to distinguish patients who are likely to respond effectively to a chemotherapeutic regimen.The taxanes, paclitaxel and docetaxel, has emerged as the most powerful chemotherapeutic drugs in the treatment of many cancers. Docetaxel is currently the most effective chemotherapeutic drug for the treatment of advanced breast cancer. However, a considerable proportion of breast cancer patients do not respond positively to docetaxel, but instead suffer from side effects. To date, the mechanisms of docetaxel sensitivity or resistance are poorly understood.In this context, the present project aims to continue and extend studies initiated in a thematic project (Processo FAPESP No. 06/01026-0) developed during the past 3 years aiming to investigate the functional role of differentially expressed genes previously identified by our group in breast cancer (Nagai et al., 2003; Nagai et al., 2004; dos Santos et al., 2006; dos Santos et al., 2009). Recently, using tissue microarrays (TMAs) containing a large number of primary breast tumors we demonstrated that PAR-4 and SPARC protein down-regulation has prognostic predictive value to distinguish patients with a more biologically aggressive invasive breast carcinoma (Nagai et al., 2010a; Nagai et al., 2010b). In the present project our goal is to investigate, in vitro, the functional role of PAR-4 and SPARC in breast cancer cell survival and sensitivity to docetaxel and 5-Fluorouracil. We will also evaluate, in vivo, the impact of SPARC expression in cancer cells and/or in the tumor microenvironment in tumor development and docetaxel chemosensitivity. In vivo studies will be conducted using nude mice SPARC-/- as a model. In vitro studies will be conducted using cell culture systems in 2D ( monolayer) and 3D (spheroids in matrigel). The three-dimensional (3D) cell culture system uses a commercially available matrix, such as MatrigelTM that is derived from the Engelbreth-Holm-Swan (EHS) murine tumor; it is a very well-established model to study breast epithelial cell biology and morphogenesis in the context of a tissue organized structure. The 3D system was established in our laboratory during the development of the thematic project to study the functional role of oncogenes and tumor suppressor genes in mammary epithelial cell morphogenesis (Nagai et al., 2010a). The 3D cell culture is also considered an important tool in studies aiming at elucidating drug sensitivity in an in vitro condition that more adequately mimetize the in vivo cell biological conditions. In the present study genomic and proteomic techniques will be used to identify the cell signaling pathways and biological processes regulated by PAR-4 and SPARC proteins. Characterization of the networks of transcripts and proteins associated with the expression of PAR-4 and SPARC might lead to the identification of new therapeutic targets and provide new insights on the mechanisms involved in cancer drug sensitivity and resistance. (AU)

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(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
PEREIRA, MICHELLY C.; DE BESSA-GARCIA, SIMONE A.; BURIKHANOV, RAVSHAN; PAVANELLI, ANA CAROLINA; ANTUNES, LOURIVAL; RANGNEKAR, VIVEK M.; NAGAI, MARIA A.. Prostate apoptosis response-4 is involved in the apoptosis response to docetaxel in MCF-7 breast cancer cells. International Journal of Oncology, v. 43, n. 2, p. 531-538, . (10/16543-5)

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