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Chordoma is a relatively rare and locally aggressive malignant tumor. Sirtuin (SIRT)5 plays pivotal roles in various tumors, but the role of SIRT5 in chordoma has not been found. This study was performed to investigate the regulatory effects of SIRT5 on cell proliferation, migration, and invasion and the underlying mechanism in chordoma. A xenograft tumor mouse model was established to assess tumor growth. Reverse transcription-quantitative polymerase chain reaction was used to analyze the mRNA levels of SIRT5 and c-myc. The effects of SIRT5 and c-myc on cell proliferation, migration, and invasion of chordoma cells were detected by cell counting kit-8, colony formation, and Transwell assays. The interaction between SIRT5 and c-myc was evaluated by co-immunoprecipitation (IP) assay. The succinylation of c-myc was analyzed by IP and Western blot. The results showed that SIRT5 expression was upregulated in chordoma tissues and cells. SIRT5 interacted with c-myc to inhibit the succinylation of c-myc at K369 site in human embryonic kidney (HEK)-293T cells. Silencing of SIRT5 suppressed the cell proliferation, migration, and invasion of chordoma cells, while the results were reversed after c-myc overexpression. Moreover, silencing SIRT5 suppressed tumor growth in mice. These findings suggested that SIRT5 promoted the malignant advancement of chordoma by regulating the desuccinylation of c-myc. [ABSTRACT FROM AUTHOR]

Background: Increasing evidence has showed that inflammatory biomarkers, including neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR) and fibrinogen can be used as predictors in the prognosis of esophageal squamous cell carcinoma (ESCC). The aim of this study was to explore prognostic value of these biomarkers and evaluate the clinicopathological and prognostic significance of combined score based on plasma fibrinogen and platelet-lymphocyte ratio (F-PLR score). Methods: A total of 506 patients with ESCC were enrolled in this study. Harrell’s concordance index (c-index) was used to determine the optimal cut-off values of these markers and evaluate their prognostic significance. The relationship between factors with survival rates (including overall survival [OS] and disease-free survival [DFS]) was explored by Kaplan-Meier curve, univariate analysis and multivariate cox hazard analysis. Results: Our result indicated that high F-PLR score was significantly associated with longer tumor length and deeper depth of tumor invasion (p < 0.01). The result of Cox multivariable analysis showed that F-PLR score was an independent prognostic factor for OS (p = 0.002) and DFS (p = 0.003). In addition, F-PLR score presented the greater c-index values for OS and DFS compared with NLR, PLR and fibrinogen level. Our result also showed that the c-index values for OS and DFS were both greater in TNM + F-PLR than those in TNM stage alone. Conclusions: In conclusion, F-PLR score is a predictive biomarker for prognosis in patients with ESCC. [ABSTRACT FROM AUTHOR]