Inhibition of L-type amino acid transporter 1 has antitumor activity in non-small cell lung cancer

BACKGROUND

L-type amino acid transporter 1 (LAT1) is highly expressed in various human neoplasms. Antitumor activity of inhibiting LAT1 was analyzed in non-small cell lung cancer (NSCLC).

MATERIALS AND METHODS

Expression of LAT1 mRNA in 54 lung cancer cell lines was examined by RT-PCR. An inhibitor of LAT1, 2-aminobicyclo-(2,2,1)-heptane-2-carboxylic acid (BCH), was administered to H1395 cell. LAT1 expression was examined in correlation with clinical features and outcome in 51 NSCLC patients.

RESULTS

Inhibition of LAT1 by BCH reduced cell viability in H1395 cells. Furthermore, co-administration of gefitinib with BCH reduced the viability of the cells more than either agent alone. Inhibition of LAT1 reduced the level of phosphorylation of mTOR, p70S6K and 4EBP1. LAT1 protein expression was closely associated with wild type EGFR, and was an independent significant factor to predict a poor prognosis.

CONCLUSION

Inhibition of LAT1 may be a new rationale to the effective therapy of NSCLC without EGFR mutation.

Neuroprotective Effect of 1-Aminocyclopropanecarboxylic Acid in a Rabbit Spinal Ischemia Model

BACKGROUND

Postoperative paraplegia remains a serious complication after repair of a thoracoabdominal aortic aneurysm. The release of the excitatory neurotransmitter glutamate might be responsible for ischemic neuronal damage. We investigated the effect of 1-Aminocyclopropanecarboxylic acid (ACPC) on the prevention of paraplegia in a rabbit model of spinal cord ischemia.

METHODS

The infrarenal abdominal aorta was clamped in eighteen rabbits. Saline (group A), 20 mg/kg of ACPC (group B), or 10 mg/kg of ACPC (group C), was injected into the clamped aorta. The animals were neurologically evaluated by Tarlov's score. The spinal cord was obtained for histopathologic examination, including hematoxylin and eosin staining and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling (TUNEL) staining method.

RESULTS

Postoperative complete paraplegia with marked neuronal necrosis appeared in group A animals. Four of the six group C animals showed intact neurological function. Scattered TUNEL positive neurons were seen within areas containing necrotic cells in sections from paraplegic animals in group A.

CONCLUSIONS

ACPC can prevent spinal cord injury in a rabbit model of spinal cord ischemia.

Charged Residues at the 2′ Position of Human GABAC ρ1 Receptors Invert Ion Selectivity and Influence Open State Probability

The ability of members of the nicotinicoid superfamily of ligand-gated ion channels to selectively conduct anions or cations is critical to their function within the central nervous system. Recent work has demonstrated that residues at the intracellular end of the second transmembrane domain, between the -3' and 2' positions, form the ion selectivity filter of these receptors. In this study, the proline residue at the 2' position (Pro-2') at the intracellular end of the second transmembrane domain of the gamma-aminobutyric acid type C rho 1 subunit was mutated to glutamate (rho 1P2'E) and arginine (rho 1P2'R). Dilution potential experiments indicated that the charge selectivity of the rho 1P2'E receptor channels had been inverted, with the channels now becoming predominantly cation selective, indicating the ability of negatively charged residues at this 2' position to control charge selectivity. The mutation was also seen to have significantly decreased agonist potency and intrinsic efficacy. In contrast, the rho 1P2'R receptor channels were anion-selective but were now found to be constitutively open with high holding currents (inhibited by low gamma-aminobutyric acid doses and the competitive antagonist, 1,2,5,6-tetrahydropyridine-4-yl)methylphosphinic acid alone) and increased agonist activity. Hill coefficients of both mutants were decreased, but competitive antagonist studies indicated that their binding sites were not significantly affected.