Overexpression of the non-coding SOX2OT variants 4 and 7 in lung tumors suggests an oncogenic role in lung cancer

Despite the advances in cancer therapy, lung cancer still remains the most leading cause of cancer death worldwide. The long non-coding RNAs (lncRNAs) are recently introduced as novel regulators of human cancers. SOX2 overlapping transcript (SOX2OT) is a cancer-associated lncRNA gene that encodes different alternatively spliced transcripts. Here, we investigated the alterations in the preferential expression of different SOX2OTs in twenty non-small cell lung cancer (NSCLC) patients by real-time quantitative reverse transcription PCR (qRT-PCR) method. We observed preferential expression of SOX2OT4 and SOX2OT7 in lung tumor tissues. The quantitative gene expression analysis revealed that >30 % of NSCLC tumors express SOX2OT4 (mean = 7.6 times) and SOX2OT7 (mean = 5.9 times) more than normal tissues, with higher expression in squamous cell carcinoma. Further, we observed overexpression of pluripotency-associated transcription factor, SOX2 in 47 % of our samples concordant with SOX2OT (R = 0.62, P value <0.05). Overexpression of OCT4A gene was also observed in 36.8 % of tumor tissues. Then, we investigated the effects of SOX2OT suppression in lung adenocarcinoma cell line, by means of RNAi. Cell characteristics of colony formation, apoptosis, 2-D mobility, and cell cycle progression were measured in control and treated A549 cells. The SOX2OT knockdown significantly reduced the colony formation ability of cancer cells; however, no alterations in the rate of apoptosis were detected. On the other hand, SOX2OT-suppressed cells had elevated accumulation in G2/M phase of cell cycle and exhibited limited mobility. Altogether, our findings support a potential oncogenic role for SOX2OT in non-small cell lung cancer tumor genesis and SOX2OT seems a promising therapeutic candidate for NSCLC. © 2016, International Society of Oncology and BioMarkers (ISOBM)

Identification of new SOX2OT transcript variants highly expressed in human cancer cell lines and down regulated in stem cell differentiation

Long non-coding RNAs are manifested as a new paradigm of molecular effectors in a wide range of human diseases. Human SOX2 overlapping transcript (SOX2OT) gene can generate six lncRNA transcript variants which are functionally assumed to be correlated with cellular differentiation and carcinogenesis. However, the circumstances determining expressional and functional differences between SOX2OT transcript variants remain to be explored. Here, we studied the expression of all SOX2OT transcript variants specifically in five human cancer cell lines by real-time RT-PCR. Changes of the new SOX2OT transcript variants expression were measured during the NT2 teratocarcinoma cell line neuronal-like differentiation and were compared to pluripotency regulators, SOX2 and OCT4A gene expressions. Surprisingly, we identified two new SOX2OT transcripts, named SOX2OT-7, SOX2OT-8 which lack exon 8. We discovered that beside active proximal and distal SOX2OT promoters, different cancer cell lines express high levels of some SOX2OT transcript variants differentially by alternative splicing. Significantly, both SOX2OT-7 and SOX2OT-8 are highly expressed in human cancer cell lines coinciding with SOX2, one of the pluripotency regulators. Our results revealed that SOX2OT-7 is almost the most abundant form of SOX2OT transcript variants in the examined cancer cell lines particularly in NT2 teratocarcinoma cell line where its expression falls upon neuronal-like differentiation similar to SOX2 and OCT4A. We suggest that at least some of SOX2OT transcripts are significantly associated with cancer and stem cell related pathways. © 2015, Springer Science+Business Media Dordrecht