Plasma lncRNA LOC338963 and mRNA AP3B2 are upregulated in paraneoplastic Lambert‐Eaton myasthenic syndrome

Lambert-Eaton myasthenic syndrome (LEMS) is an autoimmune neuromuscular junction disorder. Long noncoding RNA (lncRNA) can regulate the expression of mRNA and is involved in the development of autoimmune diseases, but few genetic studies are available. In this study we aimed to explore the lncRNA and mRNA changes of LEMS.Plasma lncRNA and mRNA expression profiles of three LEMS patients with small cell lung cancer (SCLC) and three matched healthy controls were analyzed by microarray. Differentially expressed lncRNAs and adjacent mRNAs were jointly analyzed, and candidates were verified by quantitative real-time polymerase chain reaction (qRT-PCR). The identified genes were subsequently evaluated in 9, 8, and 4 patients with paraneoplastic LEMS, nontumor LEMS, and SCLC, respectively. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed to determine possible functions.A total of 320 lncRNA and 168 mRNAs were differentially expressed in the three LEMS with SCLC and compared with healthy controls. Among these, lncRNA LOC338963 and its neighboring mRNA AP3B2 were upregulated jointly, which was confirmed by qRT-PCR. qRT-PCR revealed significant upregulation of the two genes in patients with paraneoplastic LEMS compared with nontumor LEMS or SCLC. GO analysis of AP3B2 identified the enrichment terms anterograde synaptic vesicle transport and establishment of synaptic vesicle localization. KEEG analysis showed that AP3B2 was enriched in lysosomal pathways.LOC338963 and AP3B2 were upregulated in patients with paraneoplastic LEMS, suggesting their involvement in pathogenesis. These genes could be targets for exploring the pathomechanism of paraneoplastic LEMS.