Survival strategies of papillary thyroid cancer cells in the microenvironment

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: MON 414-436-HPT Axis Biology & Action
Basic/Translational
Monday, June 17, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board MON-433
Satoshi Ogasawara*1, Yuki Tomisawa1, Go Wakabayashi2 and Yoshio Kusaka1
1Uchimaru Hospital, Morioka, Japan, 2Iwate Medical University
INTRODUCTION

Tumor dormancy is a poorly understood phenomenon conceptualized as a protracted quiescent state during which cancer cells are present but clinical disease is not apparent. Generally, following treatment of cancer, very few cancer cells can persist for years or decades under these hostile conditions that include continuous exposure to chemo/radiation therapy, autologous anti-tumor immune response, and a hypoxic / nutrient starving microenvironment. Dormant tumor cells may survive despite these unbearable-factors if they adapt and develop strategies to escape from cell death, and may progress in the future. However, this story has not proved in thyroid cancer yet. We analyzed in experimental systems in vitro and ex vivo to confirm the factors that regulate the dormant cancer cells.

Materials & Methods

For ex vivo experiments, expression of proteins related in hypoxia, nutrition, stemness, EMT, autophagy, were measured in 96 papillary thyroid cancer and 20 benign thyroid tumors by immunohistochemistry. Proteins from 10 cases of surgical materials were analized expression of these factors by western blotting.  For in vitro experiments, same factors mentioned above were analized using differentiated thyroid cancer-derived cell line (KTC1 & TPC1) with exposing to severe hypoxia/starvation (<1% O2, No FBS, No Glucose). Cell cycle, Apoptosis, and ROS were measured by Tali® Image Cytometer. Currently, the  the protein that is remarkably in experiment above was confirmed by knock-down using siRNA, and also confirmed the effect of under hypoxia/starvation.

RESULTS & DISCUSSION

In our patient cohort, local recurrences were positively correlated with Hypoxia-related protein expression. In vitro experiments, Autophagy-related protein expression were importantly for cell survival in the hypoxic microenvironment. Our results suggest that Hypoxia-related protein predicts poor survival in thyroid papillary cancer. And, autophagy system is necessary in order to thyroid cancer cell-dormancy in hypoxic microenvironment.

Nothing to Disclose: SO, YT, GW, YK

*Please take note of The Endocrine Society's News Embargo Policy at http://www.endo-society.org/endo2013/media.cfm

Sources of Research Support: Silver Group Fund 2012