Project description:We report an in situ vaccination, adaptable to nearly any type of cancer, that combines radiotherapy targeting one tumor and intratumoral injection of this site with tumor-specific antibody and interleukin-2 (IL-2; 3xTx). In a phase I clinical trial, administration of 3xTx (with an immunocytokine fusion of tumor-specific antibody and IL-2, hu14.18-IL2) to subjects with metastatic melanoma increases peripheral CD8+ T cell effector polyfunctionality. This suggests the potential for 3xTx to promote antitumor immunity against metastatic tumors. In poorly immunogenic syngeneic murine melanoma or head and neck carcinoma models, 3xTx stimulates CD8+ T cell-mediated antitumor responses at targeted and non-targeted tumors. During 3xTx treatment, natural killer (NK) cells promote CTLA4+ regulatory T cell (Treg) apoptosis in non-targeted tumors. This is dependent on NK cell expression of CD86, which is upregulated downstream of KLRK1. NK cell depletion increases Treg infiltration, diminishing CD8+ T cell-dependent antitumor response. These findings demonstrate that NK cells sustain and propagate CD8+ T cell immunity following 3xTx
Project description:Natural killer (NK) cells are the main innate antitumor effector cells and can be constrained in the tumor microenvironment (TME). It has been reported that E3 ligase FBXO38 accelerates PD-1 degradation of tumor-infiltrating T cells to unleash their cytotoxic function. In this study, we found that FBXO38 transcripts were significantly lower in intra-tumoral NK cells than in peri-tumoral regions using specimens from cancer patients in The Cancer Genome Atlas (TCGA). Conditional knock-out (cKO) of FBXO38 in NK cells accelerated tumor growth and increased tumor metastasis. However, FBXO38 deficiency did not show an effect on the cytotoxic function of tumor-infiltrating NK (TINK) cells, but decreased proliferation and survival of TINK cells. Mechanically, FBXO38 deficiency led to TINK cell hyporesponsiveness to IL-15 by reducing the expression of IL-15Rβ and IL-15Rγc, which accounted for the reduced expansion of FBXO38-deficient TINK cells in TME. Furthermore, human NK-92 cells proliferated more rapidly when FBXO38 was overexpressed and exerted greater antitumor efficacy in xenograft mouse models. Conversely, the removal of FBXO38 led to a dramatic decrease in NK-92 cell proliferation. In conclusion, our results suggest that FBXO38 strongly sustains NK cell expansion in the antitumor immunity response.
Project description:Inactivation of the von Hippel-Lindau (VHL) E3 ubiquitin ligase protein is a hallmark of clear cell renal cell carcinoma (ccRCC). Identifying how pathways affected by VHL loss contribute to ccRCC remains challenging. We used a genome-wide in vitro expression strategy to identify proteins that bound VHL only when hydroxylated. Zinc fingers and homeoboxes 2 (ZHX2) was found as a VHL target and its hydroxylation allowed VHL to regulate its protein stability. Tumor cells from ccRCC patients with VHL loss-of-function mutations usually had increased ZHX2 amount and nuclear localization. Functionally, depletion of ZHX2 inhibited VHL-deficient ccRCC cell growth in vitro and in vivo. Mechanistically, integrated ChIP-Seq and microarray analysis showed that ZHX2 promoted NF-kB activation. These studies reveal ZHX2 as a potential therapeutic target for ccRCC.
Project description:The liver has an exceptional capacity for regeneration which is crucial for maintaining liver function. Since transcriptional regulation of genes controlling metabolism and cell division is a hallmark of liver regeneration (LR), we investigated the role of Zinc-finger and homeboxes 2 (ZHX2), a transcription factor critical for regulating liver postnatal gene expression and hepatic lipid hemostasis, in LR. Our results show that hepatocyte-specific Zhx2 knockout (Zhx2-KOhep) enhances LR after 2/3 partial hepatectomy in mice. Proteomics assays revealed higher mitochondrial oxidative phosphorylation (OXPHOS) in Zhx2-KOhep mouse livers. Oxygen consumption rate (OCR) and ATP generation assays confirmed the enhanced OXPHOS in Zhx2-KOhep mouse livers and human hepatocytes with ZHX2 knockdown.