Lactate Dehydrogenase A as a Potential New Biomarker for Thyroid Cancer

BACKGROUND: Several cancers show increased levels of lactate dehydrogenase A (LDHA), which are associated with cancer progression. However, it remains unclear whether LDHA levels are associated with papillary thyroid cancer (PTC) aggressiveness or with the presence of the PTC prognostic marker, the BRAF(V600E) mutation. This study aimed to evaluate the potential of LDHA as a PTC prognostic marker. METHODS: LDHA expression was examined in 83 PTC tissue specimens by immunohistochemistry. Human thyroid cell lines were genetically manipulated to overexpress BRAF(V600E) or were treated with a BRAF-specific short hairpin RNA (shBRAF), whose effects on LDHA expression were evaluated by Western blotting. Data from 465 PTC patients were obtained from The Cancer Genome Atlas (TCGA) database and analyzed to validate the in vitro results. RESULTS: LDHA was aberrantly overexpressed in PTC. Intense immunostaining for LDHA was observed in PTC specimens carrying mutated BRAF, whereas the intensity was less in wild-type BRAF samples. Overexpression of BRAF(V600E) resulted in LDHA upregulation, whereas treatment with shBRAF downregulated LDHA in human thyroid cell lines. Furthermore, LDHA mRNA expression was significantly elevated and associated with BRAF(V600E) expression in thyroid cancer tissues from TCGA database. Additionally, LDHA overexpression was found to be correlated with aggressive clinical features of PTC, such as lymph node metastases and advanced tumor stages. CONCLUSION: LDHA overexpression is associated with the BRAF(V600E) mutation and an aggressive PTC behavior. Therefore, LDHA may serve as a biomarker and therapeutic target in PTC.