Long Noncoding RNA Expression in Adrenal Cortical Neoplasms

Long noncoding RNAs (lncRNAs) consist of nucleic acid molecules that are greater than 200 nucleotides in length and they do not code for specific proteins. A growing body of evidence indicates that these lncRNAs have important roles in tumorigenesis. Separating adrenal cortical adenomas from carcinomas is often a difficult problem for the surgical pathologist. This is especially true when only small needle biopsies are available for examination. We used in situ hybridization (ISH) analysis to study normal adrenal cortical tissues and adrenal cortical tumors to determine the role of specific lncRNAs in tumor development and classification. The lncRNAS studied included metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), psoriasis susceptibility-related RNA gene induced by stress (PRINS), and HOX antisense intergenic RNA myeloid 1 (HAM1). We constructed a tissue microarray (TMA) for the studies and also analyzed a subset of cases by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). Two 1-mm duplicate cores of normal adrenal cortex (NAC) (n = 23), adrenal cortical adenomas (ACAs) (n = 95), and adrenal cortical carcinomas (ACCs), (n = 20) were used on the TMA. The results of ISH were analyzed by image analysis. ISH showed predominantly nuclear expression of lncRNAs in adrenal cortical tissues. MALAT1 showed more expression in ACCs than in NAC and ACA (p < 0.05). PRINS had higher expression in NACs and ACAs than in ACCs. The lncRNAs MALAT1, PRINS, and HAM1 are all expressed in normal and neoplastic adrenal cortical tissues. MALAT1 had the highest expression in ACC compared to ACAs and may have a role in ACC development.