Satellite DNA transcripts in blood plasma as potential markers of tumor growth

Abstract

Recent studies of human and animal tumor tissues revealed a high transcriptional activity of pericentromeric satellite DNA repeats; i.e., they were found to produce up to half of all transcripts in tumor cells, which is many times more than in normal cells. It was also found that the two subtypes of satellite DNA (HSATII and GSATII) are transcribed reciprocally, i.e., HSATII transcripts strongly dominate in tumors, while GSATII transcripts are more abundant in the corresponding normal tissues. Since different RNAs are present in blood plasma, and some of them serve as efficient tumor markers, this study was undertaken to evaluate for the first time satellite HSATII and GSATII RNA levels in the plasma of healthy donors and cancer patients. The RT-PCR protocol designed for this purpose enabled detection of both HSATII and GSATII transcripts. It was shown that HSATII transcripts were more abundant than GSATII RNAs in the plasma of healthy donors, and this relationship was inverse in the plasma of cancer patients; these ratios were exactly opposite to those that exist within normal and tumor cells. Some notions concerning the probable origins of circulating satellite RNAs and their role as potential tumor markers are discussed.