Mutant TP53 switches therapeutic vulnerability during gastric cancer progression within interleukin-6 family cytokines

Although aberrant activation of the KRAS and PI3K pathway alongside TP53 mutations account for frequent aberrations in human gastric cancers, neither the sequence nor the individual contributions of these mutations have been clarified. Here, we establish an allelic series of mice to afford conditional expression in the glandular epithelium of Kras G12D;Pik3ca H1047R or Trp53 R172H and/or ablation of Pten or Trp53. We find that Kras G12D;Pik3ca H1047R is sufficient to induce adenomas and that lesions progress to carcinoma when also harboring Pten deletions. An additional challenge with either Trp53 loss- or gain-of-function alleles further accelerated tumor progression and triggered metastatic disease. While tumor-intrinsic STAT3 signaling in response to gp130 family cytokines remained as a gatekeeper for all stages of tumor development, metastatic progression required a mutant Trp53-induced interleukin (IL)-11 to IL-6 dependency switch. Consistent with the poorer survival of patients with high IL-6 expression, we identify IL-6/STAT3 signaling as a therapeutic vulnerability for TP53-mutant gastric cancer. </p

A hypermorphic epithelial β-catenin mutation facilitates intestinal tumorigenesis in mice in response to compounding WNT-pathway mutations

Activation of the Wnt/β-catenin pathway occurs in the vast majority of colorectal cancers. However, the outcome of the disease varies markedly from individual to individual, even within the same tumor stage. This heterogeneity is governed to a great extent by the genetic make-up of individual tumors and the combination of oncogenic mutations. In order to express throughout the intestinal epithelium a degradation-resistant β-catenin (Ctnnb1), which lacks the first 131 amino acids, we inserted an epitope-tagged ΔN(1-131)-β-catenin-encoding cDNA as a knock-in transgene into the endogenous gpA33 gene locus in mice. The resulting gpA33ΔN-Bcat mice showed an increase in the constitutive Wnt/β-catenin pathway activation that shifts the cell fate towards the Paneth cell lineage in pre-malignant intestinal epithelium. Furthermore, 19% of all heterozygous and 37% of all homozygous gpA33ΔN-Bcat mice spontaneously developed aberrant crypt foci and adenomatous polyps, at frequencies and latencies akin to those observed in sporadic colon cancer in humans. Consistent with this, the Wnt target genes, MMP7  and Tenascin-C, which are most highly expressed in benign human adenomas and early tumor stages, were upregulated in pre-malignant tissue of gpA33ΔN-Bcat mice, but those Wnt target genes associated with excessive proliferation (i.e. Cdnn1, myc) were not. We also detected diminished expression of membrane-associated α-catenin and increased intestinal permeability in gpA33ΔN-Bcat mice in challenge conditions, providing a potential explanation for the observed mild chronic intestinal inflammation and increased susceptibility to azoxymethane and mutant Apc-dependent tumorigenesis. Collectively, our data indicate that epithelial expression of ΔN(1-131)-β-catenin in the intestine creates an inflammatory microenvironment and co-operates with other mutations in the Wnt/β-catenin pathway to facilitate and promote tumorigenesis

Catalysing change in health and medical research policy: an Australian case study of deliberative democracy to reform sex and gender policy recommendations

Revising public health policy based on new data does not happen automatically. This is acutely relevant to the now undeniable evidence that many diseases develop differently between the sexes and may also be affected by gender. Current health and medical practices across the globe generally fail to cater for sex and gender effects in common diseases. Inadequate policy frameworks to guide the comprehensive inclusion of sex and gender in research jeopardises scientific rigour and ultimately the practices they underpin. To ensure that Australian health and medical research is fit-for-purpose, we realised that potent initiatives would be necessary to expedite strategic reframing of thought and behaviour. Here we report on our innovative engagement of end-users for democratic self-determined policy reform to guide health and medical research, based on robust data. We draw upon our specific study to outline seven key steps that can be adopted to accelerate effective change, across a breadth of evidence-based initiatives to reform health policies

IL33 and Mast Cells—The Key Regulators of Immune Responses in Gastrointestinal Cancers?

The Interleukin (IL-)1 family IL33 is best known for eliciting type 2 immune responses by stimulating mast cells (MCs), regulatory T-cells (Tregs), innate lymphoid cells (ILCs) and other immune cells. MCs and IL33 provide critical control of immunological and epithelial homeostasis in the gastrointestinal (GI) tract. Meanwhile, the role of MCs in solid malignancies appears tissue-specific with both pro and anti-tumorigenic activities. Likewise, IL33 signaling significantly shapes immune responses in the tumor microenvironment, but these effects remain often dichotomous when assessed in experimental models of cancer. Thus, the balance between tumor suppressing and tumor promoting activities of IL33 are highly context dependent, and most likely dictated by the mixture of cell types responding to IL33. Adding to this complexity is the promiscuous nature by which MCs respond to cytokines other than IL33 and release chemotactic factors that recruit immune cells into the tumor microenvironment. In this review, we integrate the outcomes of recent studies on the role of MCs and IL33 in cancer with our own observations in the GI tract. We propose a working model where the most abundant IL33 responsive immune cell type is likely to dictate an overall tumor-supporting or tumor suppressing outcome in vivo. We discuss how these opposing responses affect the therapeutic potential of targeting MC and IL33, and highlight the caveats and challenges facing our ability to effectively harness MCs and IL33 biology for anti-cancer immunotherapy.</p

Abstract 252: STAT3 signaling in the tumor microenvironment promotes primary gastric cancer growth and metastasis formation

Abstract Tumor cell intrinsic activation of Signal Transducer and Activator of Transcription 3 (STAT3) signaling has been shown to promote stemness, tumorigenesis and cancer therapy resistance. Therefore, Stat3 inhibitors are being developed and tested pre-clinically and in clinical trials for multiple solid cancers. Importantly, STAT3 signaling also occurs in the non-tumor cells within the tumor microenvironment (TME). The effect of Stat3 signaling within the TME on primary gastric cancers (GC), metastasis formation and therapy responses is unknown. Here, we describe a novel genetically defined, tumor organoid-driven, transplantable, orthotopic gastric cancer model that represents gastric carcinomas with associated metastasis formation in immune competent recipient mice. Utilizing our murine GC organoid model in subcutaneous allograft experiments, we showed that established GC tumors respond to pharmacological Stat3 inhibition. This anti-tumor effect is primarily driven by inhibition of the Stat3 signaling in the TME as tumor growth was increased in Stat3 high TME recipients, while tumor growth was inhibited in Stat3-signaling reduced Stat3+/- mice. Furthermore, Crisp-Cas9 -mediated Stat3 knockout in the GC organoids did not alter their in vitro growth potential. Stat3KO GC allograft tumor growth was not changed compared to Stat3WT GC tumors grown in wildtype host mice. Collectively, this suggests that inhibition of Stat3 signaling within the TME but not the tumor cell intrinsic Stat3 reduction confer anti-tumor responses. Through gastric serosa transplantation of the murine GC organoids into Stat3-elevated gp130FF mutant mice, we confirmed that high Stat3 signaling within the TME promotes distal metastasis formation to the liver. Taken together, we show that Stat3 signaling represents a therapy target, that predominantly acts through the TME. Better understanding of the signaling within the TME in primary and metastatic GC lesions will allow identification of novel tumor cell and TME-centric therapy targets. Combination of therapies targeting tumor cell intrinsic vulnerabilities with novel pro-tumorigenic TME -targeting agents could help to improve responses against primary and metastatic disease and therefore improve outcome for the worst prognosis patients. Citation Format: Moritz Eissmann, Anne Huber, Amr Allam, Christine Dijkstra, Matthias Ernst. STAT3 signaling in the tumor microenvironment promotes primary gastric cancer growth and metastasis formation [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 252.</jats:p