Plasma and tissue free amino acid profiles and their concentration correlation in patients with lung cancer

Variation of plasma free amino acids (PFAAs) is an essential feature of protein metabolic abnormalities in cancer patients. But there still little data about the cancer tissue free amino acid (TFAAs) profiles, including their patterns and correlations with PFAAs. To evaluate the variation in PFAAs and cancer TFAAs in patients with lung cancer, including their patterns and correlations, we investigated the concentrations of free amino acids in lung cancer tissues (n=27), paired lung paracarcinomous tissues (n=27) and plasma (n=27) using an automatic amino acid analyzer after pre-treatment. Within the PFAAs, the concentrations of five amino acids (tryptophan, glycine, citrulline, ornithine and proline) were significantly decreased, while that of phenylalanine was markedly increased compared with control subjects. Within the TFAAs, the concentrations of three amino acids (taurine, glutamic acid and glycine) were increased, while the concentrations of two amino acids (lysine and ornithine) were decreased significantly in lung cancer tissues compared with the paracarcinomous tissues. The amino acid patterns in PFAAs and TFAAs had similar trends, but percentage variations were diverse. Additionally, the concentrations of five amino acids (lysine, phenylalanine, threonine, serine, and alanine) in PFAAs correlated with those in lung cancer TFAAs, but no amino acids in PFAAs were correlated with those in lung paracarcinomous TFAAs. Thus, PFAA profiles may reflect the status of cancer tissues, which may provide more information about the metabolic statuses and prognoses of patients with lung cancer.