Progress report: Melanoma microRNA biomarker project

Brighton and Sussex Medical School (BSMS)  working with the Myfanwy Townsend Melanoma Research Fund  – By Sophie Mumford

Melanoma remains the most aggressive form skin cancer with an increasing incidence worldwide. Surgical resection of a non-metastatic melanoma (stage I/II) can result in disease-free intervals; however recurrence is common often resulting in progression to metastatic melanoma (stage III/IV) and death within 5 years.

This presents a pressing need to establish biomarker signatures that allow identification of patients at high risk of recurrence, to enhance their likelihood of survival, as there are now a number of drugs available that are effective against certain subtypes of melanoma.

 

Circulating microRNAs are emerging as promising non-invasive cancer biomarkers. MicroRNAs are small non-coding RNAs that function in gene silencing and post-transcriptional control on gene expression. These miRNAs are stable in the circulating blood because they are encapsulated in exosomes or are bound to protective proteins such as AGO2.

Indeed, a number of studies have demonstrated that the dynamics of microRNA expression in circulation is altered in melanoma patients, and a number microRNA biomarker signatures have been identified from circulating blood which can differentiate between melanoma patients and healthy controls.

Relatively few studies have used staged samples to identify microRNA biomarkers that can distinguish non-metastatic melanoma from metastatic melanoma. Therefore, the aim of our study is to identify microRNA biomarkers from the circulating blood to detect recurrence in malignant melanoma.

To recap, previous work carried out at the Blond McIndoe Research Foundation and the Brighton and Sussex Medical School identified 3 potential microRNA biomarkers that can distinguish Stage I/II from Stage III/IV melanoma, plus three potential reference controls.

Professor Sarah Newbury

Recent funding from the Myfanwy Townsend Melanoma Research Fund has provided me with the exciting opportunity to work alongside Professor Sarah Newbury and her research team, to check and validate the microRNA biomarkers identified in these initial experiments. Since our previous report, I have performed 474 qRT-PCR assays to quantify the relative levels of the three potential biomarkers and three normalisers in RNA extracted from the serum of 20 healthy, 20 stage I/II and 20 stage III/IV donors.

I recently re-analysed the primary data upon which this project was built and identified two additional potential biomarkers which will also be analysed in these samples using qRT-PCR.

 

Sophie Mumford in the lab. in Brighton

Currently only a few molecules of microRNA biomarkers extracted from serum can be measured using RT-qPCR and it has been reported that the RNA extraction method can affect detection, therefore I will re-extract RNA from the remaining serum of these donors using an alternative extraction method, and repeat all RT-qPCR assays to provide an additional level of validation.

To assess the extraction efficiency of the two RNA extraction kits, I will collect serum from healthy donors, add spike-in control and run an equal volume of each sample through each kit, followed by comparison using RT-qPCR. Alongside my lab work, I am in the process of conducting a literature review on the identification of circulating microRNA biomarkers in melanoma and related cancers. So far, I have collected 16 publications on this topic.

I have also designed a spread sheet to summarise the identified microRNA biomarkers in these papers, as well as listing the exact methods that each group has used. The information that I collect will be used to inform the introduction and/or some of the discussion in our publication.

Sophie will be updating this report each month. For further information on this important research project contact info@melanoma-fund.co.uk.

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