Researchers at Exiqon published an application note describing the use of the company’s miRCURY LNA™ microRNA arrays and Tecan’s HS Pro™ hybridization station for microRNA profiling of carcinomas of unknown primary (CUP) origin. The goal of the study was to develop a classifier tool based on microRNA profiles for CUP diagnosis and the classifier itself was subsequently used to identify the tumor type of a patient suffering from CUP by analyzing a biopsy from a lymph node metastasis.
Eighteen tissues, which represent the most common tissues of origin of CUP, were included in the analysis. The microRNA expression levels of these samples were analyzed and a unique microRNA profile for each of the 18 tissues was generated. Thus, CUP samples can now be compared to these expression profiles in order to locate their origin, report the scientists, who add that detailed analysis of these results revealed that a cancer classifier based on seven microRNAs is sufficient.
A biopsy from a lymph node metastasis from a patient suffering from CUP was profiled on the miRCURY LNA microRNA array. The microRNA expression level of the metastasis was compared to the average expression level across the 18 tissues.
Based on a simple cluster analysis, the lymph node metastasis microRNA profile was shown to belong to the colorectal microRNA cluster and was thus identified as colorectal cancer. Indeed, a primary colon tumor was found in this patient.
In this case, based on the microRNA profile alone, one would be able to direct the treatment against a colon cancer without having to perform a full-body PET scan searching for the primary tumor, concluded the scientists.