Abstract A1: Long stress-induced non-coding transcripts (LSINCTs) and Cancer

Abstract We previously utilized a whole genome tiling array to identify novel transcripts which had altered expression in response to the genotoxic effects of the tobacco carcinogen NNK. Our goal was to identify novel long stress-induced non-coding transcripts that could play important regulatory roles within cells and be important targets of alteration during cancer formation. Utilizing very stringent criteria, we examined all transcriptionally active regions that had altered expression in response to NNK treatment and identified a group of 12 transcripts, termed long stress-induced noncoding trancripts (LSINCTs). These novel long non-coding transcripts are between 2 and 4 Kb in length and do not contain any open reading frames or have homology to any mRNAs. 11 LSINCTs are intergenically located and one LSINCT is intragenically located within the genome. We found LSINCTs to be more highly expressed in more proliferative normal human tissues and to be frequently over-expressed in a number of different cancers including breast cancer. We studied one of these transcripts in greater detail, LSINCT5. We found LSINCT5 to be a polyadenylated nuclear transcript of exactly 2,647 base pairs. It is highly over-expressed in both breast and ovarian cancers and knocking down its' expression in either a breast or ovarian cancer cell line resulted in decreased cellular proliferation. We further compared gene expression in the breast cancer cell line, MCF7, before and after knocking down LSINCT5 expression and identified a number of genes whose expression changed more than 2-fold in response. Two of the genes identified were the gene for the major paraspeckle protein PSPC1, and another long non-coding transcript NEAT1. Paraspeckles are irregularly shaped compartments found in the nucleus' interchromatin space. Paraspeckles are RNA-protein structures formed by the interaction of NEAT1 and members of the Drosophila Behavior Human Splicing family of proteins including PSPC1. Paraspeckles appear to be critical to the control of gene expression through the nuclear retention of certain species of RNA. It is though that paraspeckles and their components play a role in controlling gene expression during a number of different cellular processes including differentiation, viral infection and stress responses. Using RNA fluorescent in situ hybridization, we found LSINCT5 to co-localize with NEAT1 within the nucleus. Hence, this novel stress-induced transcript may be another important long non-coding transcript that is involved in the normal cellular function of the paraspeckles. Citation Format: David I. Smith, Silva M. Jessica. Long stress-induced non-coding transcripts (LSINCTs) and Cancer [abstract]. In: Proceedings of the AACR Special Conference on Noncoding RNAs and Cancer; 2012 Jan 8-11; Miami Beach, FL. Philadelphia (PA): AACR; Cancer Res 2012;72(2 Suppl):Abstract nr A1.