Abstract 5796: Targeting poorly differentiated and anaplastic thyroid cancer microenvironment via TNF-α/TGF-β/LOX signaling to improve drug delivery and treatment efficacy

Abstract

Abstract A major limitation of current systemic solid cancer therapies is the failure to effectively deliver drugs to cancer cells. Solid tumors have high cell density and poor lymphatic drainage, leading to higher interstitial fluid pressure (IFP). We previously showed that the tumor microenvironment of poorly-differentiated (PDTC) and anaplastic thyroid cancer (ATC) can be selectively and effectively treated with nanomedicine carrying recombinant human Tumor Necrosis Factor α (TNFα)(CYT6091), resulting in vascular leakage, decreased IFP, and increased intratumoral concentration of paclitaxel in vivo. The purpose of this study is to investigate the mechanisms involved in a TNFα-induced reduction of IFP. We investigated the effects of TNF-α on cytokines and extracellular matrix (ECM) proteins in tumor microenvironment. Our data showed that TNFα treatment downregulated transforming growth factor-beta (TGF-β) and Lysyl oxidase (LOX) and upregulated several ECM proteins. However, we observed LOX upregulation when we treated thyroid cancer with siTNF-α-receptor 1 or 2 followed by TNF-α, suggesting the involvement of TNF-α-receptors in treatment resistance. In addition to the role of LOX in stiffening the ECM, causing a barrier to drug delivery, we showed overexpression of LOX in aggressive thyroid cancer. We observed increased vascular leakage in siLOX-treated thyroid cancer xenografts, mimicking the effect of CYT-6091. Furthermore, we confirmed that the LOX expression in thyroid cancer is positively associated with transforming growth factor receptor 1 (TGFBR1). In TCGA thyroid cancer database the mRNA expression of TGFBR1 was positively correlated with those of ECM regulatory genes (ITGB2, ITGA2 and COL1A1) which were downregulated with TNF-α treated thyroid cancer cells. To assess the role of TGF-β on vascular permeability, we found that the TGF-β inhibitor (SB-431542) induced in vitro vascular leakage, while the recombinant TGF-β reversed TNF-α-induced in vitro vascular leakage in HUVEC cells. SB-431542 and TGF-β neutralizing antibodies independently and markedly improved treatment efficacy of paclitaxel in in vitro thyroid cancer 3D tumor spheroids. Moreover, TGF-β1 inhibition downregulates the protein levels of Smad3 molecules in thyroid cancer cells. TCGA database studies of thyroid cancer patient samples showed that SMAD3 positively correlated with TGFBR1 and LOX, suggesting the involvement of SMAD3 in TGF-β/LOX signaling in the TME. Citation Format: DIPRANJAN LAHA. Targeting poorly differentiated and anaplastic thyroid cancer microenvironment via TNF-α/TGF-β/LOX signaling to improve drug delivery and treatment efficacy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5796.