Presentation Authors: Maihulan Maimaiti*, Shinichi Sakamoto, Masahiro Sugiura, Minhui Xu, Yasutaka Yamada, Kosuke Higuchi, Keisuke Ando, Nobushige Takeshita, Akira Komiya, Yuzuru Ikehara, Chiba, Japan, Yosikatsu Kanai, Osaka, Japan, Naohiko Anzai, Tomohiko Ichikawa, Chiba, Japan
Introduction: Cancer cells take up massive amounts of amino acids for survival. L-type amino acid transporter 1(LAT1) transports essential amino acids, including leucine, which triggers the downstream m-TOR pathway. In collaboration, we have created JPH203, a novel tyrosine analog, inhibits LAT1 selectively without affecting other types of the transporter, which went through Phase I clinical trial in Japan. Here we study examined 1) the association between bladder cancer and LAT1 expression, and 2) study the role of JPH203 in
Methods: Gene expression was compared by Real-Time PCR and expression of related proteins was examined by Western blotting. SiRNA was used for knocking down the target gene. triggers experiment of bladder cancer cell line was performed using LAT1 inhibitor JPH203. Genes related to LAT1 were analyzed using RNA-Seq. 68 total cystectomy patient`s data was used to study the clinical relevance. Univariate and multivariate Cox hazard proportional models and the Kaplan-Meier method were used for the statistical analysis.
Results: LAT1 was highly expressed in 5637 cells and T24 cells. LAT1 knockdown and JPH203 (10ÂµM and 20ÂµM) suppressed cell proliferative, invasive and migratory ability. JPH203 inhibited phosphorylation of MAPK / Erk, AKT, p70S6K and 4EBP-1. JPH 203 inhibits C14 leucine uptake while increasing apoptosis. IGFBP-5 was identified as a gene that significantly changed (0.35 times) by SiLAT1 by RNA-Seq analysis. SiIGFBP-5 suppressed the cell proliferation in two bladder cancer cell lines (p < 0.05). In proportional hazard analysis, the LAT1 expression (HR5.60 p=0.0142), grade (HR4.78 p=0.0194) and smoke (HR6.04 p=0.0036) are the independent predictors of overall survival in bladder cancer patients who received total cystectomy. On Kaplan-Meier analysis, patients with high expression of LAT1+IGBP-5 showed significantly poor survival compared to the low expression of LAT1+IGFBP-5 (p=0.0013).
Conclusions: LAT1 potentially contributed to the progression of bladder cancer cells through IGFBP-5 related pathway. Since JPH 203 underwent the phase I clinical trial in solid cancer patients, the clinical benefit of JPH203 in bladder cancer patient is awaited to be investigated.