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This article is part of the supplement: São Paulo Advanced School of Comparative Oncology: Abstracts

Open Access Poster presentation

Differential expression profile of microRNAs associated with human breast cancer progression

Augusto LF Marino1, Adriane F Evangelista1, Taciane Macedo1, Henrique CS Silveira1, Ligia M Kerr2, Rene AC Vieira3, Adhemar F Longatto1 and Márcia MCM Silveira1*

Author Affiliations

1 Molecular Oncology Research Center, Barretos Cancer Hospital, Barretos, SP, Brazil

2 Department of Pathology, Barretos Cancer Hospital, Barretos, SP, Brazil

3 Department of Mastology and Breast Reconstruction, Barretos Cancer Hospital, Barretos, SP, Brazil

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BMC Proceedings 2013, 7(Suppl 2):P9  doi:10.1186/1753-6561-7-S2-P9


The electronic version of this article is the complete one and can be found online at: http://www.biomedcentral.com/1753-6561/7/S2/P9


Published:4 April 2013

© 2013 Marino et al; licensee BioMed Central Ltd.

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Background

MicroRNAs (miRNAs) negatively regulate gene expression and its deregulation is involved in cancer progression. Our aim was to verify which miRNAs may play a role in breast cancer progression, especially metastasis.

Materials and methods

MicroRNA expression profiles were generated by microarray analysis (Agilent) of 70 samples from primary breast tumors with different clinical staging. Data were analyzed using bioinformatics software (R, Cluster and Tree View), which allowed sample discrimination (metastatic vs. non metastatic tumors) by hierarchical clustering of breast cancer expression signatures. We performed a second analysis using the ROC curve method that allowed us to identify miRNAs with greater predictive potential of malignancy. Furthermore, by Venn diagram analysis, we were able to identify 8 miRNAs that were differentially expressed in all metastatic tumors of different clinical staging, compared to the primary non-metastatic tumors. SPSS 19 software was used to generate a Kaplan-Meier curve (p<0.05) to estimate the disease-specific survival (considering the specific event such as death by cancer), based on miRNA expression patterns.

Results

We found four miRNAs previously described as potentially oncogenic (hsa-let-7a, hsa-let-7b, hsa-let-7c and hsa-miR-21) for breast cancer, being hsa-let7a, hsa-let7b and hsa-miR-21 under-expressed in the metastatic vs non-metastatic tumors, and four new miRNAs candidates for markers of metastasis (has-miR-1308, has-miR-923, hsa-miR-328, has-miR-494), the first two were over-expressed while the latest ones were under-expressed in metastatic vs non-metastatic tumors.

Conclusions

We identified two groups of miRNAs whose expression level were associated with worse prognosis. These findings are important for better understanding of the role of miRNAs in breast cancer progression.

Financial support

FAPESP.