Proteomic analysis reveals the heterogeneity of metabolic reprogramming in lacrimal gland tumors.

Lacrimal gland adenoid cystic carcinoma (ACC) is associated with high recurrence and mortality rates. Many recent studies have focused on the clinical features of the disease, and a better understanding of its underlying molecular mechanisms may help guide future treatment strategies. For proteomics quantitation, we analyzed normal tissues, benign tumor tissues and ACC tissues by LC-MS/MS with Tandem mass tags (TMTs) labeling. Bioinformatics analysis of the KEGG pathway found that, compared with normal tissues, the expression levels of major proteins related to cell metabolism were lower in benign tumors and cancer tissues of the lacrimal gland. In addition, we also performed IHC staining to verify the expression of representative proteins in tissue samples. All of these results indicated that compared with normal tissues, lacrimal gland tumors had unique metabolic reprogramming characteristics. Further Short Time-series Expression Miner (STEM) analysis revealed that glycine, serine and threonine metabolism in ACC tissues was significantly enhanced compared with that in normal tissues and benign tumor tissues. This finding suggested that glycine, serine and threonine metabolism might be the key to the malignant transformation of ACC; thus, assessing the metabolism in these tissues could be an effective approach enabling the early diagnosis of ACC, and the proteins involved in these metabolic pathways could represent therapeutic targets.