Correlation of mismatch repair deficiency with clinicopathological features and programmed death-ligand 1 expression in thyroid carcinoma.

BACKGROUND: Mutations in DNA mismatch repair (MMR) genes associated with thyroid carcinoma (TC) have rarely been reported, especially in East Asian populations. METHODS: We examined tumor tissue from a cohort of 241 patients diagnosed with TC between 2008 and 2020. MMR proteins were detected using tissue microarray-based immunohistochemistry in order to identify MMR-protein-deficient (MMR-D) and MMR-protein-intact (MMR-I) tumors. We retrospectively summarized the clinicopathologic characteristics of patients with MMR-D TC, measured the expression of PD-L1, and recorded overall survival (OS) and other clinical outcomes. RESULTS: In our cohort, there were 18 (7.5%) MMR-D (MLH1, MSH2, MSH6, and PMS2) patients, including 12 with papillary TC (PTC) (6.7%), 2 with poorly differentiated TC (PDTC) (4.7%), and 4 with anaplastic TC (ATC) (22.2%). Half of them (9/18) showed a specific deletion in MSH6, and 6 of them also carried variants in the MSH6 and PMS2 gene. Survival was significantly better in patients with MMR-D ATC than in those with MMR-I tumors (p = 0.033). Four of the 18 MMR-D patients (22%) were found to be PD-L1 positive. Their OS was much shorter than that of PD-L1-negative patients. CONCLUSIONS: MMR-D and PD-L1 positivity appear to be associated with clinicopathological characteristics and prognosis in TC. The results indicate that MMR status may have important prognostic significance in TC. Therefore, immune checkpoint inhibitors that target the PD-1/PD-L1 pathway may be a treatment option for TCs.

Silencing of PPM1D inhibits cell proliferation and invasion through the p38 MAPK and p53 signaling pathway in papillary thyroid carcinoma.

Endeavors towards identifying key molecular markers for early diagnosis and treatment are driving the clinical study of papillary thyroid carcinoma (PTC). Recent studies have indicated that protein phosphatase, Mg2+/Mn2+ dependent, 1D (PPM1D) exerts an oncogenic function by increasing cell proliferation, migration and invasion in various cancer types. In addition, PPM1D has a high frequency of genetic alterations and has been proposed as a tumor driver in thyroid cancer, making PPM1D an attractive potential oncotarget for cancer treatment. The aims of the present study were to investigate the downstream targets of PPM1D and the potential molecular mechanisms of its oncogenic activities, as well as its clinical significance in PTC. As anticipated, PPM1D overexpression was confirmed in PTC clinical specimens. Furthermore, knockdown of PPM1D in thyroid cancer cell lines significantly suppressed the proliferation, migration and invasion but facilitated cell apoptosis. The protein levels of phosphorylated p38 mitogen­activated protein kinase (MAPK), p53 and Bax were increased in PPM1D­knockdown cells, while inhibition of p38 phosphorylation restored cell migration, proliferation and cell apoptosis. In addition, silencing of PPM1D expression induced nuclear translocation of p53 in K­1 and TPC­1 cells. The present results demonstrated that PPM1D regulated p38 MAPK and p53 signaling pathways to promote thyroid cancer progression. Collectively with the clinical results, these data qualified PPM1D as a potential diagnostic biomarker and therapeutic target in human thyroid cancer.

Germline Missense Mutation of Deleted in Malignant Brain Tumor 1 (DMBT1) in Familial Mediastinal Neuroendocrine Cancer and in vitro Effects in Thyroid Cancer Cells.

BACKGROUND: Neuroendocrine tumors (NETs) rarely occur in the mediastinum and their etiology and pathogenesis are still unclear. OBJECTIVES: This study assessed inherited or de novo mutations in familial mediastinal NETs. METHOD: DNA samples from 4 patients were subjected to the whole-exome sequencing, and Sanger sequencing was used to identify Deleted in malignant brain tumor 1 (DMBT1) mutations in all 45 family members. RESULTS: All patients showed a germline DMBT1 mutation at 4971C. Sanger sequencing data showed that 4 NETs and 2 carriers in the first patient's family and 2 NETs and 4 carriers in the second patient's family, respectively, had this DMBT1 mutation. The in vitro data showed that the ectopic expression of DMBT1 reduced tumor cell viability and migration by arresting the G1/S phase of the cell cycle. CONCLUSIONS: We identified a germline missense mutation in DMBT1D1657E as a susceptibility gene for familial mediastinal NETs.

Prognostic Nomograms for Predicting Overall Survival and Cancer-Specific Survival of Patients with Major Salivary Gland Mucoepidermoid Carcinoma.

Background: The aim of this study was to develop and validate prognostic nomograms predicting overall (OS) and cancer-specific survival (CSS) of patients with major salivary gland (MaSG) mucoepidermoid carcinoma (MEC). Methods: 1398 MaSG-MEC patients were identified from the Surveillance, Epidemiology and End Results (SEER) database. They were randomly and equally divided into a training cohort (n=699) and a validation cohort (n=699). The best subsets of covariates were identified to develop nomograms predicting OS and CSS based on the smallest Akaike Information Criterion (AIC) value in the multivariate Cox models. The nomograms were internally and externally validated by the bootstrap resampling method. The predictive ability was evaluated by Harrell's Concordance Index (C-index). Results: For the training cohort, eight (age at diagnosis, tumor grade, primary site, surgery, radiation, T, N and M classification) and seven predictors (all the above factors except primary site) were selected to create the nomograms estimating the 3- and 5- year OS and CSS, respectively. C-index indicated better predictive performance of the nomograms than the 7th AJCC staging system, which was confirmed by both internal (via the training cohort: OS: 0.888 vs 0.785, CSS: 0.938 vs 0.821) and external validation (via the validation cohort: OS: 0.844 vs 0.743, CSS: 0.882 vs 0.787). The calibration plots also revealed good agreements between the nomogram-based prediction and observed survival. Conclusions: We have proposed and validated the nomograms predicting OS and CSS of MaSG-MEC. They are proved to be of higher predictive value than the AJCC staging system and may be adopted in future clinical practice.

IL-17A increases MHC class I expression and promotes T cell activation in papillary thyroid cancer patients with coexistent Hashimoto's thyroiditis.

BACKGROUND: The incidence of coexisting papillary thyroid cancer (PTC) and Hashimoto's thyroiditis (HT) is increasing. The impact of HT on PTC prognosis and its possible mechanism remains controversial. Interleukin-17A (IL-17A) has been reported to participate in the pathogenesis of multiple autoimmune diseases and cancers. The aim of this study is to investigate the role of IL-17A in PTC with coexistent HT and evaluate the changes in tumor antigenicity. METHODS: Expression of IL-17A and major histocompatibility complex (MHC) class I molecules were compared on PTC tissue samples with or without HT. PTC cell lines K1 and TPC-1 were stimulated with IL-17A and analyzed for MHC class I expression afterwards. Cluster of differentiation (CD) 8+T cell activation, production of Interleukin-2 (IL-2) and Interferon-gamma (IFN-γ) as well as the programmed death-1 (PD-1) expression on lymphocytes were assessed by coculture of donor peripheral blood lymphocytes (PBLs) with IL-17A pretreated PTC cells. RESULTS: Elevated IL-17A and MHC class I expression were observed in PTC tissue samples with coexistent HT. Stimulation of PTC cells with IL-17A effectively increased MHC class I expression in vitro. Coculture of PBLs with IL-17A pretreated PTC cells resulted in enhanced T cell activation (%CD25+ of CD3+T cells) and increased IL-2 production along with decreased IFN-γ secretion and PD-1 expression of the lymphocytes. CONCLUSIONS: Papillary thyroid cancer with coexisting Hashimoto's thyroiditis presents elevated MHC class I expression, which may be the result of IL-17A secretion. T cell activation is enhanced in vitro by IL-17A and may provide future utility in PTC immunotherapy.

Histone methyltransferase KMT5A gene modulates oncogenesis and lipid metabolism of papillary thyroid cancer in vitro.

KMT5A (known as PR-Set7/9, SETD8 and SET8), a member of the SET domain containing methyltransferase family specifically targeting H4K20 for methylation, has been implicated in multiple biological processes. In the present study, we identified that KMT5A was elevated in 50 pairs of papillary thyroid cancer tissue samples and in cell lines K1 and TPC-1 by qRT-PCR and western blotting, as well as by immunohistochemical staining. CCK-8 assay and flow cytometric analysis revealed that inhibition of KMT5A attenuated proliferation and induced apoptosis. Transwell assays revealed that cell migration and invasion were suppressed in KMT5A-knockdown cells. Moreover, the inhibition of KMT5A arrested the cell cycle in the G1/S phase of papillary thyroid cancer cells. The TCGA data revealed that elevated KMT5A expression was significantly correlated with extrathyroidal extension, lymph node metastasis and advanced pathological stage of papillary thyroid cancer. Furthermore, we observed that inhibition of KMT5A suppressed the expression of SREBP1, SCD, FASN and ACC, key molecules involved in lipid metabolism and decreased the level of malondialdehyde in papillary thyroid cancer cells. In conclusion, KMT5A may be a novel oncogenic factor, specifically a regulator for lipid metabolism in papillary thyroid carcinoma.