Prognostic Value of LDHD and Its Correlation With Immune Infiltrates in Thyroid Cancer

Background: LDHD is a subtype of the LDH family that can participate in D-lactate metabolism. However, the expression of LDHD in tumors and its role in tumor immunity are currently unknown. The objective of this research was to estimate the expression and prognosis of LDHD in pan-cancer and to explore the communication between LDHD expression level and tumor immune infiltration.Methods: LDHD expression level in pan-cancer was explored by TIMER and UALCAN databases and the prognostic value of LDHD was explored by Kaplan Meier plotter and PrognoScan databases. Then, the correlation between LDHD expression level and immune cell infiltration was evaluated by the TIMER database. In addition, the relationship between LDHD expression and clinical features of THCA was verified in the TCGA database. Results: The expression of LDHD mRNA or protein is downregulated in varied tumor types, and LDHD expression level is significantly related to the prognosis in tumors. Moreover, the downregulation of LDHD was found related to increased immune-cell infiltration and worse clinical features, especially in thyroid cancer.Conclusion: LDHD may be a potential pan-cancer prognostic biomarker. In thyroid cancer, loss of expression of LDHD may mediate tumor initiation and progression by affecting immune cell infiltration.