Differential TNFα and Toll-like-receptor 4-signaling in endocrine tumors after tumor-vascular-disrupting agent ASA404 (vadimezan) and TNFα treatment

C Hantel; R Lira; A Ozimek; R Frantsev; M Reincke; T Mussack; F Beuschlein

doi:10.1055/s-0034-1372034

Experimental and Clinical Endocrinology & Diabetes, Table of Contents

Differential TNFα and Toll-like-receptor 4-signaling in endocrine tumors after tumor-vascular-disrupting agent ASA404 (vadimezan) and TNFα treatment

C Hantel ¹, R Lira ², A Ozimek ³, R Frantsev ¹, M Reincke ¹, T Mussack ³, F Beuschlein ¹

¹Endocrine Research Unit, Medizinische Klinik and Poliklinik IV, Ludwig-Maximilians-University, Munich, Germany
²Pediatrics Department, FMRP-USP, Ribeirão Preto, Brazil
³Department of Surgery, Ludwig-Maximilians-University, Munich, Germany

Abstract

ASA404 (Vadimezan) belongs to a class of agents with disrupting properties against tumor vasculature. Herein, putative therapeutic applicability was investigated in preclinical models for neuroendocrine tumors of the gastroenteropancreatic system (BON) and adrenocortical carcinoma (NCIh295). Upon treatment of tumor bearing mice we detected a significant disruption of microvessels, decrease in cell proliferation, increase of apoptotic cells and extensive necrosis in BON tumors while no comparable effects were detectable in those of NCIh295 origin. As TNFα-signaling had been proposed to mediate parts of ASA404 dependent effects we utilized these models based on their different responsiveness for characterization of TNFα synthesis and signaling in vitro and in vivo. While NCIh295 tumors showed higher basal TNF receptor 1 expression and a comparable increase in serum TNFα levels, a significant increase in intra-tumoral TNFα secretion as well as TNFα-specific activation of downstream NFκB and caspase 3/7 signalling was present mainly in the BON model. Furthermore, we detected high levels of Toll-like-receptor (TLR)-4 and a significant increase in the expression of its adaptor protein MD-2 specifically in ASA404 treated BON tumors, while both was not detectable for NCIh295. As TNFα is an important downstream component of the TLR-network this could be an additional reason for intra-tumoral TNFα alterations. Moreover, we identified several members of an inhibitory feedback loop downstream of both pathways, including TNFAIP3/A20, TNIP1 and NFKκBIA, as elevated at baseline in the adrenocortical carcinoma tumor model suggesting basal inhibition of both pathways as one putative reason for the detected impairment in therapeutic response.