Georgia Papachristopoulou1, Emmanuel I Papadopoulos2, Afrodite Nonni3, George Z Rassidakis4, Andreas Scorilas5. 1. First Department of Pathology, School of Health Sciences, Faculty of Medicine, National and Kapodistrian University of Athens, Athens, Greece; Department of Biochemistry and Molecular Biology, Faculty of Biology, National and Kapodistrian University of Athens, Athens, Greece; Department of Pathology, "Saint Savvas" Cancer Hospital of Athens, Athens, Greece. 2. Department of Biochemistry and Molecular Biology, Faculty of Biology, National and Kapodistrian University of Athens, Athens, Greece. 3. First Department of Pathology, School of Health Sciences, Faculty of Medicine, National and Kapodistrian University of Athens, Athens, Greece. 4. First Department of Pathology, School of Health Sciences, Faculty of Medicine, National and Kapodistrian University of Athens, Athens, Greece; Department of Oncology and Pathology, Karolinska University Hospital and Karolinska Institutet, Stockholm, Sweden. 5. Department of Biochemistry and Molecular Biology, Faculty of Biology, National and Kapodistrian University of Athens, Athens, Greece. Electronic address: ascorilas@biol.uoa.gr.
Abstract
BACKGROUND: Aberrations in microRNA levels seem to provide valuable information regarding breast cancer prognosis and therapy. In this study, we sought to analyze miR-29b expression in breast tumors and thus explore its clinical value. MATERIALS AND METHODS: One hundred twenty-one malignant and 56 benign breast tissue specimens were collected and subjected to extraction of total RNA, which was polyadenylated and reverse transcribed to cDNA. Subsequently, a highly sensitive quantitative real-time polymerase chain reaction protocol was developed and miR-29b levels, estimated via the comparative CT method, were finally subjected to comprehensive statistical analysis. RESULTS: MiR-29b levels did not differ between the analyzed benign and malignant breast tissue specimens, but were found to be significantly (P = .010) decreased in invasive ductal adenocarcinomas compared with their lobular counterparts, albeit receiver operating characteristics curve analysis did not verify the latter correlation. Additionally, miR-29b expression was elevated in samples with positive estrogen receptor status (P = .021) in the overall population, whereas it was negatively correlated (P = .035) with primary tumor staging in the ductal subset and increased in poorly-differentiated tumors of lobular origin (P = .041). Furthermore, Kaplan-Meier and Cox regression analyses showed that patients with ductal carcinoma and elevated miR-29b levels had a significantly longer disease-free survival (P = .010) and a lower risk to relapse (hazard ratio = 0.35, 95% confidence interval, 0.15-0.81; P = .014). CONCLUSION: Our results provide evidence that miR-29b levels constitute a promising biomarker of favorable prognosis for patients with invasive ductal breast carcinoma and imply that its expression status might be affected by the histological origin of breast malignancy.
BACKGROUND: Aberrations in microRNA levels seem to provide valuable information regarding breast cancer prognosis and therapy. In this study, we sought to analyze miR-29b expression in breast tumors and thus explore its clinical value. MATERIALS AND METHODS: One hundred twenty-one malignant and 56 benign breast tissue specimens were collected and subjected to extraction of total RNA, which was polyadenylated and reverse transcribed to cDNA. Subsequently, a highly sensitive quantitative real-time polymerase chain reaction protocol was developed and miR-29b levels, estimated via the comparative CT method, were finally subjected to comprehensive statistical analysis. RESULTS:MiR-29b levels did not differ between the analyzed benign and malignant breast tissue specimens, but were found to be significantly (P = .010) decreased in invasive ductal adenocarcinomas compared with their lobular counterparts, albeit receiver operating characteristics curve analysis did not verify the latter correlation. Additionally, miR-29b expression was elevated in samples with positive estrogen receptor status (P = .021) in the overall population, whereas it was negatively correlated (P = .035) with primary tumor staging in the ductal subset and increased in poorly-differentiated tumors of lobular origin (P = .041). Furthermore, Kaplan-Meier and Cox regression analyses showed that patients with ductal carcinoma and elevated miR-29b levels had a significantly longer disease-free survival (P = .010) and a lower risk to relapse (hazard ratio = 0.35, 95% confidence interval, 0.15-0.81; P = .014). CONCLUSION: Our results provide evidence that miR-29b levels constitute a promising biomarker of favorable prognosis for patients with invasive ductal breast carcinoma and imply that its expression status might be affected by the histological origin of breast malignancy.