Certain short strands of RNA, known as microRNAs (miRNAs), have been linked to the progression and metastasis of breast cancer and may provide information about prognosis. However, studies of miRNA expression profiles often report conflicting findings. While the potential for using miRNAs in breast cancer diagnosis is promising, scientists report in a new study published online today in The Journal of Molecular Diagnostics that differences in the amount and types of miRNA within breast tumors can be misleading.
"Personalized medicine will be the future of cancer care," explains lead investigator Stefanie Avril, MD, of the Technical University of Munich. "However, taking a single tumor biopsy for defining individual treatment is probably oversimplified, and we need to take into account the heterogeneity of tumors. "We found considerable differences in the expression of miRNAs associated with breast cancer within a single tumor (referred to as intratumoral heterogeneity). The use of miRNA for diagnosis or prognosis requires sampling at several different tumor locations and of several tumor-involved lymph nodes."
Researchers collected 132 tumor samples from 16 patients who underwent either lumpectomy or mastectomy for large primary invasive breast cancer. Samples were taken from defined tumor zones: the center of the tumor, the periphery, and the area between. Samples were also taken from lymph nodes, if metastases were present. The expression of four miRNAs (miR-31, miR-335, miR-10b, and miR-210) and four control genes (let-7a, miR-16, RNU48, and RNU44) was assessed.
The researchers found significant variation in miRNA expression, from samples both within primary breast cancers and within lymph node metastases from the same patient. The extent of heterogeneity was very similar within the defined tumor zones and between different zones.
To illustrate why intratumoral heterogeneity may produce misleading results if only a single sample is used, the researchers assessed the variation of miRNA expression between different patients. The mean expression of miR31, which is associated with cancer metastasis, from all zones of the primary tumor site in patient 5 was significantly lower than the mean expression from all zones of the primary tumor site of patient 6. However, a sample from a single tumor zone from patient 5 showed a higher expression level than the lowest case from patient 6. "This might in part explain conflicting previous findings regarding miRNA expression profiles," Dr. Avril notes.
"An important strength of this study is the systematic and predefined prospective sampling of tumors in 8 to 10 different areas, whereas previous studies have commonly only analyzed different areas of one tumor section, or core biopsies of the same tumor," says Dr. Avril. "Reliable assessment of breast cancer miRNA profiles should include sampling of the primary tumor in several locations or sampling several tumor-involved lymph nodes when deriving miRNA expression profiles from metastases."
David Sampson | EurekAlert!
23.03.2017 | Technische Universität München
How prenatal maternal infections may affect genetic factors in Autism spectrum disorder
22.03.2017 | University of California - San Diego
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
23.03.2017 | Life Sciences
23.03.2017 | Power and Electrical Engineering
23.03.2017 | Earth Sciences