SOD3 induces a HIF-2α-dependent program in endothelial cells that provides a selective signal for tumor infiltration by T cells

Abstract

BackgroundTumor-infiltrating lymphocytes (TILs), mainly CD8+ cytotoxic T lymphocytes (CTL), are linked to immune-mediated control of human cancers and response to immunotherapy. Tumors have nonetheless developed specific mechanisms that selectively restrict T cell entry into the tumor microenvironment. The extracellular superoxide dismutase (SOD3) is an anti-oxidant enzyme usually downregulated in tumors. We hypothesize that upregulation of SOD3 in the tumor microenvironment might be a mechanism to boost T cell infiltration by normalizing the tumor-associated endothelium.ResultsHere we show that SOD3 overexpression in endothelial cells increased in vitro transmigration of naïve and activated CD4+ and CD8+ T cells, but not of myeloid cells. Perivascular expression of SOD3 also specifically increased CD4+ and CD8+ effector T cell infiltration into tumors and improved the effectiveness of adoptively transferred tumor-specific CD8+ T cells. SOD3-induced enhanced transmigration in vitro and tumor infiltration in vivo were not associated to upregulation of T cell chemokines such as CXCL9 or CXCL10, nor to changes in the levels of endothelial adhesion receptors such as intercellular adhesion molecule-1 (ICAM-1) or vascular cell adhesion molecule-1 (VCAM-1). Instead, SOD3 enhanced T cell infiltration via HIF-2α-dependent induction of specific WNT ligands in endothelial cells; this led to WNT signaling pathway activation in the endothelium, FOXM1 stabilization, and transcriptional induction of laminin-α4 (LAMA4), an endothelial basement membrane component permissive for T cell infiltration. In patients with stage II colorectal cancer, SOD3 was associated with increased CD8+ TIL density and disease-free survival. SOD3 expression was also linked to a T cell–inflamed gene signature using the COAD cohort from The Cancer Genome Atlas program.ConclusionOur findings suggest that SOD3-induced upregulation of LAMA4 in endothelial cells boosts selective tumor infiltration by T lymphocytes, thus transforming immunologically “cold” into “hot” tumors. High SOD3 levels are associated with human colon cancer infiltration by CD8+ T cells, with potential consequences for the clinical outcome of these patients. Our results also uncover a cell type–specific, distinct activity of the WNT pathway for the regulation of T cell infiltration into tumors.

SOD3 boosts T cell infiltration by normalizing the tumor endothelium and inducing laminin-α4

“…In mouse tumor models, LAMA4 levels correlated positively with TIL density after SOD3 overexpression; in contrast, LAMA4 and TIL were reduced after endothelial HIF-2α deletion or WNT pathway inhibition. 6 These data support LAMA4 as a SOD3 mediator for TIL infiltration.…”

“…4 We reported that perivascular SOD3 triggers a program that simultaneously induces vascular normalization and T cell infiltration, thus linking these two processes unequivocally. 5,6 The anti-oxidant enzyme SOD3 is usually downregulated in tumors, which suggests that its loss is advantageous for cancer progression. 7 SOD3 catalyzes the dismutation of the superoxide radical (•O 2 − ) in the extracellular space; this activity not only prevents oxidative damage of lipids or proteins but also preserves the bioavailability of nitric oxide (NO).…”

“…In vivo, perivascular SOD3 accumulation increases infiltration of adoptively transferred and endogenous tumor-specific T cells. 6 Specific HIF-2α deletion in the tumor endothelium causes a reduction in TIL numbers, which pinpoints HIF-2α as a necessary SOD3 mediator. SOD3 overexpression in the TME increases the CD8 + / FoxP3 + ratio compared to controls, 6 which suggests distinct SOD3 effects on effector and regulatory T cell transmigration.…”

“…β-catenin levels are elevated in SOD3overexpressing cells; however, β-catenin neither translocates to the nucleus nor induces transcription of canonical βcatenin-regulated genes in SOD3-overexpressing cells. 6 It accumulates massively in the juxtamembrane area, probably due to β-catenin sequestration by VEC at AJ. SOD3 induces nuclear accumulation of another WNTinduced transcription factor, FoxM1, whose deficiency causes vascular abnormalities.…”

Changes in the Activity and Concentration of Superoxide Dismutase Isoenzymes (Cu/Zn SOD, MnSOD) in the Blood of Healthy Subjects and Patients with Acute Pancreatitis

“…SOD3 is known as a predominant form of SODs in plasma [ 10 ]. In many studies, it has been shown that SOD3 is mainly expressed in endothelial cells [ 11 , 26 , 27 ], and its decrease was associated with vascular endothelium damage and the infiltration of inflammatory cells [ 5 , 10 , 28 ]. In our previous study [ 29 ], we demonstrated an increased concentration of endothelium damage markers in AP patients which could be associated with decreased SOD3 concentration in the plasma of these patients.…”