Long non‑coding RNA transcribed from pseudogene PPIAP43 is associated with radiation sensitivity of small cell lung cancer cells

Small cell lung cancer (SCLC) is a highly lethal disease. Although radiation therapy is effective for the majority of patients with SCLC, patient sensitivity to radiation varies. The lack of biomarkers impedes advances in targeting radiation-sensitive patients. In this study, the changes in transcription patterns of SCLC cell lines were evaluated with or without 2 Gy gamma radiation. The results demonstrated that peptidyl-prolyl cis-trans isomerase A pseudogene 43 (PPIAP43) transcription was increased 2-fold in cells irradiated with 2 Gy gamma radiation compared with unirradiated cells in pre-reported radio-sensitive sensitive cell lines H69, H128, H146, H209 and H187. These cells shared 259 upregulated and 96 downregulated RNA transcripts following radiation. Pre-reported less sensitive cell lines H526, D53, D114 and D153 in which PPIAP43 was not upregulated 2-fold following irradiation with 2 Gy gamma radiation compared with unirradiated cells, shared 3 upregulated and 9 downregulated RNA transcripts. The RNA transcript of PPIAP43 was aligned with the mRNA of peptidyl-prolyl cis-trans isomerase A (PPIA) at 2 sections (3,732 to 3,917 and 5,327 to 5,657 of the PPIA gene) and the sequences were shown to be 96 and 94% similar, respectively. Therefore, PPIAP43 may act as a sponge for microRNAs which bind with the RNA of PPIA. Therefore, PPIAP43 RNA transcription may serve as a potential biomarker of radio-sensitivity of SCLC.