J Cancer 2011; 2:67-75. doi:10.7150/jca.2.67 This volume

Research Paper

miR-21 Expression in Pregnancy-Associated Breast Cancer: A Possible Marker of Poor Prognosis

Beatriz A. Walter1, Gabriela Gómez-Macias2, Vladimir A. Valera1, Mark Sobel1, Maria J. Merino1

1. Laboratory of Pathology, National Institutes of Health, National Cancer Institute, Bethesda, MD, USA;
2. Department of Pathology and Cytopathology, Universidad Autonoma Nuevo Leon, Monterrey, México.

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Walter BA, Gómez-Macias G, Valera VA, Sobel M, Merino MJ. miR-21 Expression in Pregnancy-Associated Breast Cancer: A Possible Marker of Poor Prognosis. J Cancer 2011; 2:67-75. doi:10.7150/jca.2.67. Available from https://www.jcancer.org/v02p0067.htm

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Aims: microRNAs (miRNAs) are a class of small noncoding RNAs that can act as key modulators in tumorigenesis-related genes. Specifically, it has been suggested that miR-21 overexpression plays a role in the development and progression of breast cancer. So far, the role of miRNAs in pregnancy-associated breast cancer (PABC) has not been investigated.

Methods and Results: We evaluated miR-21 expression by quantitative RT-PCR in 35 patients, 25 with PABC and 10 control breast cancer cases not pregnancy-associated with similar clinicopathological features. We then analyzed protein expression for PTEN, BCL2 and PDCD4 as miR-21 target genes by IHC, and finally correlated the results with patients' clinicopathological features.

Significant overexpression of miR-21 in PABC tumors compared to normal adjacent tissue was found. Overexpression of miR-21 was frequently found in high grade tumors with loss of hormone receptor expression and was significantly associated with positive lymph nodes (p=0.025). In PABC patients, PTEN, BCL2 and PDCD4 target protein expression was decreased in 80%, 76% and 40% respectively.

Conclusion: Our study supports the involvement of miR-21 in breast cancer progression and metastasis formation in PABC implying a role of this miRNA as a marker for poor prognosis in PABC patients.

Keywords: Pregnancy-associated breast cancer, breast cancer, microRNA, miR-21, PTEN.