Abstract 4335: The role of fibroblasts in prostate cancer cell invasion in tumor microenvironments
Authors: Shah Tariq , Wildes Flonne , Artemov Dmitri , Bhujwalla Zaver M. 
Published: July 2017

Cancer-associated fibroblasts (CAFs) play a critical role in tumor aggressiveness. We have started to investigate the role of CAFs in different tumor microenvironments of hypoxia and acidic extracellular pH. To further understand interactions between CAFs and cancer cells under carefully controlled conditions of hypoxia and acidic pH, we have used our MR compatible cell perfusion system to determine, for the first time, changes in the ability of prostate cancer cells to invade and degrade the extracellular matrix (ECM) in the presence of prostate myofibroblasts.

Experiments were performed using the human prostate cancer cell lines PC-3 and prostate myofibroblasts (WPMY-1, ATCC, Manassas, VA). Before each MR experiment, 2.5X106 PC-3 cells were seeded on 0.5 ml of Plastic Plus beads in five 100mm dishes and grown for 4 days. Experiments were carried out with PC-3 cells plated on an ECM chamber with or without prostate myofibroblasts layered between the PC-3 and the ECM. For experiments investigating prostate myofibroblasts-cancer cell interaction, 5 X 104 prostate myofibroblasts were seeded on ECM gel contained in a chamber overnight before the MR experiment. This time interval allowed myofibroblasts to attach to the ECM gel. Degradation of ECM by cancer cells was determined at the 24h time point relative to the initial time point from the proton images. MR data were acquired on a 9.4 T MR spectrometer every 12 h over a period of 2 days. T1-weighted 1H MR imaging was performed to evaluate changes in ECM invasion and degradation. The extent of ECM degradation was estimated by drawing a region of interest (ROI) around the ECM gel region using NIH ImageJ software. The degradation index was defined as (ROIt=0-ROIt=24)/ROIt=0. One-dimensional 1H MR profiles of intracellular water were acquired along the length (z-axis) of the sample by diffusion- weighted MRI. These profiles were used to derive an invasion index by quantifying the number of cells invading into the ECM.

Fibroblasts alone marginally degraded the matrigel. PC-3 cells, being invasive cells also degraded the ECM. However, ECM degradation increased when prostate myofibroblasts were layered between the ECM and the PC-3 prostate cancer cells. Consistent with the degradation data, PC-3 cells showed a significant increase in the invasive index in the presence of myofibroblasts under normoxia. The enhanced invasion and degradation of ECM by PC-3 cells in the presence of myofibroblasts suggests that the interaction between myofibroblasts and PC-3 cells plays a role in prostate cancer invasion. Further studies with hypoxia and acidic pH microenvironment are currently ongoing.

Citation Format: Tariq Shah, Flonne Wildes, Dmitri Artemov, Zaver M. Bhujwalla. The role of fibroblasts in prostate cancer cell invasion in tumor microenvironments [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4335. doi:10.1158/1538-7445.AM2017-4335