EACR 2016

miRNA screening through nipple aspiration sampling

Dr Cathy Moelans - University Medical Center Utrecht, Utrecht, Netherlands

Today I presented some data about the feasibility of detecting microRNAs in nipple aspiration fluid samples. Nipple aspiration fluid samples are quite challenging; we obtain them non-invasively by aspiration under vacuum using a pump system that is similar to what is used for breast feeding. We generally get only a few droplets of NAF, so 10-20μl, so the sample volumes are really low. We want to use NAF samples as a means to predict breast cancer development at a very early stage so basically as a new screening tool for breast cancer. We think that this might particularly be interesting for women carrying a BRCA1 or 2 mutation because these women have a 6-8 times higher risk of developing breast cancer and they often develop the disease at a young age and with a more aggressive phenotype than usual. Up to 55% of these women will not develop breast cancer before the age of 70 but nevertheless many of these women opt at a very young age, so around the age of 35, for a prophylactic bilateral mastectomy, the preventive removal of both breasts which, of course, is a mutilating and psychologically distressing procedure. So by exploring a novel way to study the breast microenvironment based on the detection of microRNAs in these nipple aspiration fluid samples we hope to be able to find a new way to predict breast cancer development at a very early stage.

What more can you tell us about your study?

So far we’ve only done a small pilot and we found some significantly dysregulated microRNAs in the cancer setting but the sample size was too small to really conclude something about it. But at least we’ve found already a few interesting microRNAs. We need to expand the experiments so basically what I talked about today was more the feasibility of detecting these microRNAs in NAF and more basic things we need to know, such as how do these microRNA patterns fluctuate in time because if we want to use them as a biomarker we don’t want them to fluctuate too much during menstrual cycle, for example. I also demonstrated that the fluctuation is quite acceptable.

What techniques are you currently using?

We look at microRNAs using qPCR and we’ve tested different platforms because I already mentioned detecting microRNAs in these limited NAF samples is quite difficult. So we’ve compared different platforms and we’ve now selected the most sensitive one. That’s how it works and we chose to look at microRNAs because they are tiny RNA molecules that can influence gene expression and they are known to play a role in carcinogenesis and they have been shown to be dysregulated in many cancer types, including breast cancer. These microRNAs are released into biofluids and it has been shown that the release of these microRNAs by tumour cells into the corresponding biofluids is selective and therefore they may correlate to malignancy so that’s why we focus on microRNAs.

How do you see your research progressing in the near future?

We’ve now demonstrated that microRNA expression analysis in these limited NAF samples is not only feasible but also highly reproducible. This was just the first step, moving forward to a larger biomarker discovery study. We have started collecting NAF samples from women carrying a BRCA1 and 2 mutation and also other women that are at increased risk of developing breast cancer. We started collecting these samples already back in 2008; so far we’ve included 600 women and we’re still including at the moment and we obtain NAF and blood from these women each year and follow them up for ten years. So part of these women will develop breast cancer during follow-up and it will be interesting to look at microRNA levels in these samples while these women are developing breast cancer. In that way we will be able to find a microRNA biomarker panel that can predict breast cancer development at a very early stage.

Are the microRNA changes similar between cancers?

Many researchers have looked at microRNA expression in blood and there have been some systematic reviews comparing microRNAs that were found to be dysregulated in blood samples in those different studies but it has been shown that none of these studies actually finds the same microRNAs. So I think that is a big problem when using blood, that it’s not very specific. You can also have microRNA change when you have an inflammation somewhere in your body or something else and we believe that using the fluid from the source will be the solution.