A new cancer/testis long noncoding RNA, the OTP-AS1 RNA

The orthopedia homeobox (OTP) gene encodes a homeodomain-containing transcription factor involved in brain development. OTP is mapped to human chromosome 5q14.1. Earlier we described transcription in the second intron of this gene in wide variety of tumors, but among normal tissues only in testis. In GeneBank these transcripts are represented by several 300-400 nucleotide long AI267901-like ESTs. We assumed that the AI267901-like ESTs belonged to the longer transcript(s). We used the Rapid Amplification of cDNA Ends (RACE) approach and other methods to find the full-length transcript. The transcript we found was a 2436 nucleotide polyadenylated sequence in antisense to OTP gene. The corresponding gene consisted of two exons separated by an intron of 2961 bp. The first exon was found to be 91 bp long and located in the third exon of OTP. The second exon was 2345 bp long and located in the second intron of OTP. We have shown the expression of this gene in many human tumors but as few as a single sample of normal testis. The transcript lacked significant ORFs suggesting that we discovered a new antisense cancer/testis (CT) sequence OTP-AS1 (OTP-antisense RNA 1), which belongs to the class of long noncoding RNAs (lncRNAs). According to our findings we assume that OTP-AS1 and OTP genes may be a CT-coding gene/CT-ncRNA pair, or sense-antisense gene pair involved in regulatory interactions.