Papillary Mucinous Adenocarcinoma of the Endolymphatic Sac: A Rare Middle Ear Neoplasm

Comprehensive analysis of DNA methylation gene expression profiles in GEO dataset reveals biomarkers related to malignant transformation of sinonasal inverted papilloma

BACKGROUND

DNA methylation may be involved in the regulation of malignant transformation from sinonasal inverted papilloma (SNIP) to squamous cell carcinoma (SCC). The study of gene methylation changes and screening of differentially methylated loci (DMLs) are helpful to predict the possible key genes in the malignant transformation of SNIP-SCC.

MATERIALS AND METHODS

Microarray dataset GSE125399 was downloaded from the Gene Expression Omnibus (GEO) database and differentially methylated loci (DMLs) were analyzed using R language (Limma package). ClusterProfiler R package was used to perform Gene Ontology (GO) analysis on up-methylated genes and draw bubble maps. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway and its visualization analysis were analyzed to speculate the possible key Genes in SNIP-SCC malignant transformation. Subsequently, SNIP cases archived in our department were collected, tissue microarray was made, and immunohistochemical staining was performed to analyze the expression levels of UCKL1, GSTT1, HLA-G, MAML2 and NRGN in different grades of sinonasal papilloma tissues.

RESULTS

Analysis of dataset GSE125399 identified 56 DMLs, including 49 upregulated DMLs and 7 downregulated DMLs. Thirty-one genes containing upregulated DNA methylation loci and three genes containing downregulated DNA methylation loci were obtained by methylation microarray annotation analysis. In addition, KEGG pathway visualization analysis of 31 up-methylated genes showed that there were four significantly up-methylated genes including UCKL1, GSTT1, HLA-G and MAML2, and one significantly down-methylated gene NRGN. Subsequently, compared with non-neoplasia nasal epithelial tissues, the expression of HLA-G and NRGN was upregulated in grade I, II, III and IV tissues, while the expression of MAML2 was lost. The protein expression changes of MAML2 and NRGN were significantly negatively correlated with their gene methylation levels.

CONCLUSIONS

By analyzing the methylation dataset, we obtained four up-regulated methylation genes UCKL1, GSTT1, HLA-G and MAML2 and one down-regulated gene NRGN. MAML2, a tumor suppressor gene with high methylation modification but loss of protein expression, and NRGN, a tumor gene with low methylation modification but upregulated protein expression, can be used as biological indicators to judge the malignant transformation of SNIP-SCC.

Symptoms and clinical features in patients affected by endolymphatic sac tumor: a systematic review and meta-analysis

PURPOSE

Most ELST data in the literature are case studies or limited to small cohorts (< 16 patients). We evaluated the main clinical signs observed at endolymphatic sac tumor (ELST) diagnosis in patients with or without Von Hippel-Lindau disease.

METHODS

We conducted a comprehensive literature search in PubMed, Scopus, and Web of Science. We included studies with at least 1 patient, of any age, affected by sporadic or VHL-related ELSTs reporting levels of hearing loss and facial nerve function and a comprehensive description of presenting symptoms at ELST diagnosis. We combined data for proportional meta-analysis. p values of 0.05 were considered statistically significant. Methodological quality was evaluated. Analyses were performed with MedCalc 14.8.1 software.

RESULTS

A total of 26 studies, including 113 patients and 118 cases of ELSTs were included. Pooled proportion rates (95% CI) of overall hearing loss was 88.7%, (82.4-93.4), severe hearing loss was 21.6% (12.8-32.1) profound hearing loss was 39.8% (28.7-51.5), vertigo/imbalance was 42.0% (33.8-50.5), tinnitus was 61.8% (53.4-69.8) and facial nerve palsy was 30.6% (23.2-38.9). Generally, symptoms were homogeneous or moderately heterogeneous among included studies.

CONCLUSION

This is the first systematic review of clinical presentations at ELST diagnosis. The most serious clinical events include profound hearing loss and facial impairment. Fluctuating hearing loss, tinnitus and vertigo are frequently reported and may confound correct and prompt ELST diagnosis.