Selective Inhibition of L-type Amino Acid Transporter 1 Suppresses Cell Proliferation in Ovarian Clear Cell Carcinoma.

ABSTRACT

BACKGROUND/AIM: Ovarian clear cell carcinoma (OCCC) is a histological type of ovarian cancer that is refractory to chemotherapy and has poor prognosis, which necessitates the development of novel treatment therapies. In this study, we focused on L-type amino acid transporter 1 (LAT1), which is involved in cancer growth, and investigated the effect of its selective inhibition on cell proliferation in OCCC. MATERIALS AND METHODS: The inhibitory effect of nanvuranlat (JPH203), a LAT1 selective inhibitor, on the cellular uptake of [3H] leucine was evaluated using the OCCC cell line JHOC9, which expresses the LAT1 protein. In addition, the kinetics of cell proliferation and changes in phosphorylation of the mTOR pathway were analyzed. The correlation between LAT1 expression and progression-free survival (PFS) was evaluated using clinical specimens of OCCC. RESULTS: Nanvuranlat inhibited [3H] leucine intracellular uptake and cell proliferation in a dose-dependent manner in JHOC9 cells. In addition, it suppressed the activity of the mTOR signaling pathway, which is thought to inhibit cancer cell proliferation. LAT1 expression was most frequent in OCCC among clinical specimens of epithelial ovarian cancer. A correlation between LAT1 expression and PFS was observed in OCCC. CONCLUSION: LAT1 selective inhibition suppresses cell proliferation via the mTOR pathway by inhibiting leucine uptake in OCCC. This study illustrates the potential of using LAT1 selective inhibition as a treatment strategy for OCCC.