Abstract 1360: The role of inflammatory stimuli in modulating tumor derived factor expression in metastatic prostate cancer microenvironment
Authors: Banzola Irina , Mohyuddin Rizwan , Sais Giovanni , Poyet Cédric , Sulser Tullio , Provenzano Maurizio 
Published: February 2011

Tumor microenvironment is the battlefield were not well defined relationships between oncogenesis and immune surveillance to cancer take place. Upon transformation due to accumulation of several genetic mutations and epigenetic alterations, tumor cells proceed to either their full elimination or progression to overt cancer depending on immunity fitness. In particular, tumor escape occurs through the secretion of different tumor derived factors (TDFs) with immune suppressive properties, such as indoleamine, 2-3 dioxygenase (IDO), interleukin (IL) 10, transforming growth factor beta (TGF-β), and/or cytokines relevant in modulating the TDFs network. Among them, our interest focused on those microenvironmental modifiers that have been reported as possible mediators of prostate cancer (PCa) morbidity (IDO, IL-6, TGF-β).

For this study, two prostate cancer cell-lines with invasive (CA-HPV-10) and metastatic behavior (PC3) were used. After culturing upon stimulation over 24 hours with IFN-γ and TNF-α, cells were harvested, total RNA extracted and transcribed into cDNA in order to perform gene expression by using qrt-PCR. As housekeeping genes, either rRNA18S or β-actin was tested. A 2-ΔΔCt methods was used to compute fold changes among experimental conditions.

IDO-1 was constitutively higher expressed in bone metastases (20fold) than in localized cancer (2fold) and the finding was inversely correlated to serine protease inhibitor maspin expression (8-10fold less in PC3) while c-myc, relevantly expressed in both cell lines, was not modulated over time. A significant higher expression of IL-10 and IL-6 (15fold and 20fold, respectively) was detected in PC3 while there were no variations for TNF-α and TGF-β, although a constitutive strongest expression was observed for IL-6 and TGF-β in both cell-lines, as compared to the other cytokines (2000fold). IL-2 and IL-4 gene expression was almost negligible. Upon 12 hours stimulation with IFN-γ, an inducible higher amount of IDO-1 was detected (450fold) over the constitutive level but at a lesser extent for IDO-2 (20fold). However, the fold change seen between both enzymes at a constitutive expression was proportionally maintained. Conversely, TNF-α treatment produced a lower increase of expression for both IDO (5-15fold), as compared to constitutive values but a significant modulation for IL-6 over 24 hours (8fold over the baseline).

Factors involved in immune suppressions such as IDO, IL-10, TGF-β and most likely mediators for PCa morbidity, also including IL-6, appear to be expressed at higher levels during PCa progression. Furthermore, their expression is even more increased in a microenvironment characterized by inflammatory stimuli. An extended analysis on PCa patients might better inform on the role that inflammation plays in TDFs expression and activity.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1360.