Small nucleolar RNA host genes and long non-coding RNA responses in directly irradiated and bystander cells.

The irradiated cells communicate with unirradiated cells and induce changes in them through a phenomenon known as the bystander effect. The nature of the bystander signal and how it impacts unirradiated cells remains to be discovered. Examination of molecular changes could lead to the identification of pathways underlying the bystander effect. Apart from microRNAs, little is known about the regulation of other non-coding RNAs (ncRNA) in irradiated or bystander cells. In this study we monitored the transcriptional changes of several small nucleolar RNAs (snoRNAs) host genes and long non-coding RNAs (lncRNAs) that are known to participate in a variety of cellular functions, in irradiated and bystander cells to gain insight into the molecular pathways affected in these cells. We used human lymphoblasts TK6 cells in a medium exchanged bystander effect model system to examine ncRNA expression alterations. The snoRNA host genes SNHG1 and SNHG4 were upregulated in irradiated TK6 cells but were repressed in bystander cells. The SNHG5 and SNHG11 were downregulated in irradiated and bystander cells and the expression levels of these ncRNA were significantly lower in bystander cells. The lncRNA MALAT1, MATR3, SRA1, and SOX2OT were induced in irradiated TK6 cells and their expression levels were repressed in bystander cells. The lncRNA RMST was induced in both irradiated and bystander cells. Taken together, these results indicate that expression levels of ncRNA are modulated in irradiated and bystander cells and these transcriptional changes could be associated with the bystander effect.