Differential gene expression between resistant tumors and residual tumors of breast Cancer patients treated with doxorrubicin and cyclophosphamide neoadjuvant chemotherapy

• Grant number: 10/02054-2
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: April 01, 2010
• End date: March 31, 2011
• Field of knowledge: Health Sciences - Medicine - Medical Clinics
• Principal Investigator: Maria Aparecida Azevedo Koike Folgueira
• Grantee: Fernanda Kaori Fujiki
• Host Institution: Faculdade de Medicina (FM). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

One of the aims of neoadjuvant chemotherapy in locally advanced breast cancer is to reduce tumor dimension, allowing tumor resection. Although most patients present clinical objective response, around 10-20% present complete pathological response or tumor progression. Tumor resistance may be characterized as intrinsic, when stable or progressive diseases are observed or acquired when after an initial response, the tumor becomes resistant to additional chemotherapy cycles, containing the same drugs. It is unknown whether these mechanisms of resistance are similar. One important aspect is to identify possible mechanisms of resistance. Our group is involved in the determination of transcriptions profiles involved in tumor resistance. We have previously studied tumor samples from patients with breast cancer treated with neoadjuvant chemotherapy. The transcriptional profile associated with response to treatment was determined by the cDNA microarray technique. In another study, the differential gene expression of pre and post-chemotherapy samples was analyzed, in an attempt to evaluate residual tumors. Our present aim is to determine the transcriptional profile of samples considered resistant to treatment and residual samples from tumors considered responsive to treatment. This comparison may reveal mechanisms involved in the resistance mechanisms. Identified candidate genes will have their expression further evaluated in another group of patients using PCR methodology.(AU)