Characteristics of Genomic Mutations and Signaling Pathway Alterations in Thymic Epithelial Tumors

Abstract Purpose: To elucidate mechanisms of thymic epithelial tumor (TET) canceration through characterization of genomic mutations and signal pathway alterations.Methods: Primary tumor and blood samples were collected from 21 patients diagnosed with TETs (thymoma and thymic cancer), 15 of whom were screened by nucleic acid extraction and total exon sequencing. Bioinformatics was used to comprehensively analyze sequencing data for these samples, including differences in tumor mutation burden (TMB) and signaling pathways.Results: We found that the gene with the highest mutation frequency in thymic carcinoma was ZNF429 (36%). In addition, mutations in BAP1 (14%), ABI1 (7%), BCL9L (7%), CHEK2 (7%) were only detected in thymic carcinoma, whereas ZNF721 mutations (7%) were found only in thymoma. Mean TMB values for thymic carcinoma and thymoma groups were 0.722 and 0.663 mutations per megabase (Mb), respectively, differences that were not statistically significant. There were significant differences in enriched pathways for cellular components between tumor metastasis and non-metastatic samples. The ErbB signaling pathway was enriched in both the thymoma group and the intersection group, whereas “pathways in cancer” was found in both the thymoma group and thymic cancer group. In contrast, enrichment of longevity-regulating and MAPK signaling pathways was found only in the thymoma group.Conclusions: We identified multiple differences in somatic genes and pathways, providing insights into differences between thymoma and thymic carcinoma that could aid in designing personalized clinical therapy.