Study of the physiological changes associated with the development of malignancy demonstrates a metabolic signature for the different stages of tumorigenesis. Increased glucose uptake and lactate production have been detected during malignant transformation. Based on energy production, malignancies can be divided into two subclasses: (a) tumor cells which use the mitochondrial machinery for ATP synthesis, and (b) tumor cells which generate ATP by glucose fermentation and lactate production even in the presence of oxygen (aerobic glycolysis). Recently, transketolase-like protein 1 (TKTL1) gene expression has been shown to contribute to carcinogenesis through increased aerobic glycolysis and hypoxia-inducible factor alpha stabilization. In the present study, 197 patients suffering from lung cancer were investigated by immunohistochemistry for the presence of TKTL1 protein expression. We detected: (1) moderate to strong TKTL1 expression (immune reactive score>100) in 39.1% of the investigated lung cancer patients; (2) a complete lack of TKTL1 by immunohistochemistry in 12.7% of lung cancer cases, with small cell lung cancer (SCLC) being most frequent in this subgroup; (3) no correlation of TKTL1 with overall survival, disease-free survival, any of the established variables of the TNM system, grading, stage, smoking status, or gender. Based on this data, we conclude that TKTL1 could be a target protein for improved therapeutic strategies in some cases of lung cancer.
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