Despite many studies on papillary thyroid carcinoma (PTC) in the past few decades, some critical and significant genes remain undiscovered. To explore genes that may play crucial roles in PTC, a detailed analysis of the expression levels, mutations, and clinical significance of Kallikrein-related peptidases (KLKs) family genes in PTC was undertaken to provide new targets for the precise treatment of the disease. A comprehensive analysis of KLK family genes was performed using various online tools, such as GEPIA, Kaplan-Meier Plotter, LinkedOmics, GSCA, TIMER, and Cluego. KLK7, KLK10, and KLK11 were critical factors of KLK family genes. Then, functional assays were carried out on KLK7/10/11 to determine their proliferation, migration, and invasion capabilities in PTC. The mRNA expression levels of KLK7, KLK10, KLK11, and KLK13 were significantly elevated in thyroid carcinoma, while KLK1, KLK2, KLK3 and KLK4 mRNA levels were decreased compared to normal tissues. Correlations between KLK2/7-12/15 expression levels and tumor stage were also observed in thyroid carcinoma. Survival analysis demonstrated that KLK4/5/7/9-12/14 was associated with overall survival in patients with thyroid cancer. Not only were KLK genes strongly associated with cancer-related pathways, but also KLK7/10/11 was associated with immune-cell infiltration. Finally, silencing KLK7/10/11 impaired human papillary thyroid carcinoma cells' growth, migration ability, and invasiveness. The increased expression of KLK7, KLK10, and KLK11 may serve as molecular markers to identify PTC patients. KLK7, KLK10, and KLK11 could be potential prognostic indicators and targets for precision therapy against PTC.
Background: Recent research showed that abnormal lipid metabolism was associated with cancers. As one of the genes that can regulate the level of lipid metabolism, abnormal APOE expression was associated with carcinogenesis. However, the clinical value of APOE in papillary thyroid carcinoma (PTC) remains to be determined. Methods: ONCOMINE, GEPIA, UALCAN, STRING, GeneMANIA, LinkedOmics, GSCALite, TISIDB, EPIC and TIMER were utilized to achieve comprehensively bioinformatics analysis of APOE in this study. And the immunohistochemical staining of APOE was used to verify the predicted results. Results: The mRNA level and protein level of APOE of PTC tissues were significantly elevated in TCGA cohort and Shanghai cohort. PTC patients with low mRNA level of APOE were associated with a bad prognosis. The functions of APOE co-expressed genes were mainly enriched in adaptive immune response, protein-lipid complex subunit organization, actin cytoskeleton reorganization, cell chemotaxis, protein activation cascade and transcriptional misregulation in cancer. APOE level was significantly correlated with tumor-infiltrating cells (B cells, CD8+ T cells, neutrophils, and dendritic) and immune biomarkers in PTC. Conclusions: APOE is a potential independent biomarker for PTC and APOE expression is positively correlated with immune cell infiltration in PTC.
