35P - MiR-16 is the most stable-expressed housekeeping microRNA in breast cancer tissues from primary and metastatic sites

Date 07 May 2015
Event IMPAKT 2015
Session Welcome reception and Poster Walk
Topics Breast Cancer, Metastatic
Pathology/Molecular Biology
Translational Research
Presenter Gabriel Rinnerthaler
Citation Annals of Oncology (2015) 26 (suppl_3): 10-14. 10.1093/annonc/mdv116
Authors G. Rinnerthaler1, H. Hackl2, F. Hamacher1, S.P. Gampenrieder1, C. Hufnagl1, F. Romeder1, C. Monzo Fuentes1, C. Hauser-Kronberger3, B. Mlineritsch1, R. Greil1
  • 1Iiird Medical Department, Salzburg Cancer Research Institute, Paracelsus University Hospital Salzburg, 5020 - Salzburg/AT
  • 2Division Of Bioinformatics, Biocenter, Medizinische Universität Innsbruck, Innsbruck/AT
  • 3Department Of Pathology, Paracelsus University Hospital Salzburg, 5020 - Salzburg/AT

Abstract

Body

Background: For quantitative miRNA expression analyses with real-time quantitative PCR expression levels have to be normalized to endogenous controls. As miRNA expression analysis of formalin-fixed paraffin-embedded (FFPE) cancer tissue is influenced by the microenvironment and surrounding tissue, we investigated the most stable-expressed miRNA in breast cancer tissues from primary and metastatic sites.

Patients and methods: A genome-wide miRNA profiling using TaqMan® Array Human MicroRNA Cards enabling quantification of 754 unique human miRNAs was performed in FFPE specimen from 60 patients treated with bevacizumab as first-line therapy at our institution. Forty-three (72%) samples came from primary tumor and 17 (28%) from metastasis. Twenty-three (38%) of specimen were achieved by biopsies and 37 (62%) by surgery. As endogenous controls often housekeeping miRNAs are used. These are expected to show small variation and high correlation to the mean of all measured miRNAs, because the majority of microRNAs are not changing and mean normalization might be appropriate.

Results: Eleven miRNAs could be detected in all analyzed samples. Four of these miRNAs (miR-16-5p, miR-29a-3p miR-126-3p, miR-222-3p) showed also a high correlation with the median of all measured miRNAs (Spearman rank correlation rho ≥ 0.8) and therefore might be well suited as endogenous controls. U6sn, a small nuclear RNA which is thought as an endogenous control on TaqMan® Array Human MicroRNA Cards was consistently expressed across all samples from primary tumors and metastatic sites (CV = 11%). The identified miRNAs showed even more consistent expression levels with a CV from 7% to 10% and therefore considered as housekeeping miRNAs. MiR-16 might be the most promising miRNA as it was previously also used as control in serum analysis of breast cancer patients. Currently these data are being validated in a second cohort. These validated results will be presented at the meeting.

Conclusion: In breast cancer tissue from primary tumor and metastatic sites miR-16 is stably expressed. It might be considered as most relevant housekeeping miRNA and used as an endogenous control for normalization in expression analysis.

Disclosure: All authors have declared no conflicts of interest.