Aberrant allelic-switch of antisense lncRNA IRAIN may be an early diagnostic marker in laryngeal cancer

Laryngeal carcinoma is a common head and neck malignancy, however, the molecular mechanism of the disease has not yet been elucidated. The present study aimed to investigate the role of IGF1R antisense imprinted non-protein coding RNA (IRAIN) long non-coding (lnc)RNA in laryngeal carcinoma. In total, specimens of healthy pharynx tissue from 6 healthy individuals, carcinoma tissue and paracancerous tissue from 37 patients with laryngeal carcinoma were used in this study. The single nucleotide polymorphism (SNP) rs8034564 was used to distinguish the two parental alleles of IRAIN. DNA and RNA were extracted from tissue specimens and the IRAIN allelic gene was sequenced. Reverse transcription-quantitative PCR was used to determine the expression levels of IRAIN and Insulin-like growth factor 1 receptor (IGF1R) in laryngeal carcinoma and paracancerous tissue. Bisulfite genomic sequencing was used to determine IRAIN promoter DNA methylation status in laryngeal carcinoma tissue. The expression of IRAIN was di-allelic in healthy pharynx tissue, laryngeal carcinoma tissue and paracancerous tissue. Moreover, IRAIN expression in laryngeal carcinoma tissue was lower compared with paracancerous tissue (P<0.05). IRAIN expression was not associated with age, histological type, tumor stage and grade and lymph node metastasis. IRAIN allelic expression imbalance was present in laryngeal carcinoma and paracancerous tissue, but not in healthy pharynx tissue. SNP analysis (rs8034564) indicated there was an allelic-switch of the two parental alleles. Furthermore, epigenetic analysis revealed no extensive DNA methylation of CpG islands in the IRAIN gene promoter of laryngeal carcinoma. Therefore, it was suggested that IRAIN allele was non-imprinted in laryngeal carcinoma and healthy pharynx tissue. It was also demonstrated that IRAIN may be a potential tumor suppressor in laryngeal carcinoma, and that DNA methylation is not involved in the regulation of IRAIN gene immobilization in laryngeal carcinoma tissue. Thus, detection of IRAIN allelic expression imbalance and aberrant allele-switch may serve as an early diagnostic marker of laryngeal carcinoma.