HSATII RNA is induced via a non-canonical ATM-regulated DNA-damage response pathway and facilitates tumor cell proliferation and movement

Pericentromeric human satellite II (HSATII) repeats are normally silent, but can be actively transcribed in tumor cells, where increased HSATII copy number is associated with a poor prognosis in colon cancer, and in human cytomegalovirus (HCMV)-infected cells, where the RNA facilitates viral replication. Here, we report that HCMV infection or treatment of ARPE-19 diploid epithelial cells with the DNA-damaging agents, etoposide and zeocin, induced HSATII RNA expression, and a kinase-independent function of ATM was required for the induction. Additionally, various breast cancer cell lines growing in adherent, 2-dimensional cell culture expressed HSATII RNA at different levels, and levels were markedly increased when cells were either infected with HCMV or treated with zeocin. High levels of HSATII RNA expression correlated with enhanced migration of breast cancer cells, and knockdown of HSATII RNA reduced cell migration and the rate of cell proliferation. Our investigation links high expression of HSATII RNA to the DNA damage response, centered on a non-canonical function of ATM, and demonstrates a role for the satellite RNA in tumor cell proliferation and movement. SIGNIFICANCEHSATII RNA is associated with cancer progression, immunostimulation and, as we recently reported, it plays an important role in herpesvirus infections. However, the understanding of cellular processes responsible for the expression of HSATII RNA has been limited. Our current investigation identified a non-canonical, ATM kinase-independent DNA-damage response pathway as a common cellular mechanism regulating HSATII RNA induction in virus-infected cells or cells treated with DNA-damaging agents. Additionally, our study provides a link between expression of HSATII RNA and the cellular growth and migration phenotypes of cancer cells, establishing a new paradigm to study the biological consequences of HSATII RNA expression, i.e., treatment of normal diploid and tumor cells with DNA-damaging agents.