NEW YORK (GenomeWeb News) – New research suggests miRNAs hold promise as diagnostic tools for identifying metastatic cancer’s origin.
Scientists from Israel-based Rosetta Genomics and their collaborators identified several dozen miRNA biomarkers in tumor and metastatic tissue that can effectively pinpoint the tissue in which the cancer originated. The researchers say the work, which appeared yesterday in the online version of Nature Biotechnology, may ultimately have implications for cancer diagnostics, specifically for metastatic cancer of unknown primary origin.
Roughly three to five percent of new cancer cases have unknown primary origins. Although there are various cancer diagnostic tools available, including X-rays, MRI, and PET scans, there is still no reliable method for determining where metastases originated in these CUP cases.
Non-coding, regulatory miRNAs play roles both in development and in the genesis and progression of some cancers. Because they show high tissue specificity, miRNAs are a potential tool for tracking down metastatic cancer’s origin.
In an effort to explore this possibility, the researchers measured miRNA expression in about 400 samples from 22 tumor tissues and metastases using custom microarrays with probes for more than 600 miRNAs. From these, they created a transparent miRNA-based classifier using a branched binary tree classification algorithm and data from four dozen miRNAs in 253 samples.
Based on these results, as well as data gleaned from quantitative RT-PCR on 65 other blinded test samples and a K-nearest neighbors classification algorithm, the authors concluded that their miRNA biomarkers are effective for tracking down CUP origin in the majority of samples. For instance, in blinded test samples and more than 100 metastases, they could decipher between 22 tissue origins about 90 percent of the time using 48 miRNA markers.
“We developed an approach that assigns well-defined roles to individual miRNAs in classifying cancer tissue origin,” the authors wrote.
Rosetta Genomics is developing a CUP diagnostic test that it hopes to launch in Clinical Laboratory Improvement Amendments certified laboratories in the US this year.