Login to Access Video or Poster Abstract: MP44-16
Sources of Funding: This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology, Republic of Korea (2015R1A1A1A0500110), and (2015R1A2A1A15054364).

Introduction

The cross-talk of mammalian target of rapamycin (mTOR) pathway is clinical limitation of mTOR inhibitor for the treatment of urothelial carcinoma (URCa). This study is to search mTOR pathway downstream genes to overcome cross-talk at non muscle invasive low grade (LG)-URCa of the bladder.

Methods

Gene expression patterns, gene ontology, and gene clustering by dual (p70S6K and S6K) siRNAs or rapamycin in 253J and TR4 cell lines were investigated by microarray analysis and we selected mTOR/S6K pathway downstream genes which were suppressed to siRNAs, and rapamycin up-regulated or rapamycin down-regulated. We validated mTOR downstream genes with immunohistochemistry using tissue microarray of 90 non-muscle invasive LG-URCa patients whether genes can predict clinical outcomes, and knockout study to evaluate the synergistic effect with rapamycin.

Results

In the microarray analysis, we selected mTOR pathway downstream genes which consisted of 4 rapamycin down-regulated (FOXM1, KIF14, MYBL2, and UHRF1), and 4 rapamycin up-regulated (GPR87, NBR1, VASH1 and PRIMA1). In tissue microarray, FOXM1, KIF14, and NBR1 were more expressed at T1, and MYBL2 and PRIMA1 were more expressed at tumor size more than 3 cm. In multivariate Cox regression model, KIF14 and NBR1 were significant predictors of recurrence in non-muscle invasive LG-URCa of the bladder. In NBR1 knock out model, rapamycin treatment showed synergistic effect to inhibit cell viability and colony forming ability compared to rapamycin only.

Conclusions

KIF14 and NBR1 were mTOR/S6K pathway downstream genes to predict recurrence in non-muscle invasive LG-URCa of the bladder and NBR1 knockout overcome the rapamycin coss-talk.

Funding

This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology, Republic of Korea (2015R1A1A1A0500110), and (2015R1A2A1A15054364).