Ablative radiotherapy improves survival but does not cure autochthonous mouse models of prostate and colorectal cancer.

BACKGROUND: Genetically engineered mouse models (GEMMs) of cancer are powerful tools to study mechanisms of disease progression and therapy response, yet little is known about how these models respond to multimodality therapy used in patients. Radiation therapy (RT) is frequently used to treat localized cancers with curative intent, delay progression of oligometastases, and palliate symptoms of metastatic disease. METHODS: Here we report the development, testing, and validation of a platform to immobilize and target tumors in mice with stereotactic ablative RT (SART). Xenograft and autochthonous tumor models were treated with hypofractionated ablative doses of radiotherapy. RESULTS: We demonstrate that hypofractionated regimens used in clinical practice can be effectively delivered in mouse models. SART alters tumor stroma and the immune environment, improves survival in GEMMs of primary prostate and colorectal cancer, and synergizes with androgen deprivation in prostate cancer. Complete pathologic responses were achieved in xenograft models, but not in GEMMs. CONCLUSIONS: While SART is capable of fully ablating xenografts, it is unable to completely eradicate disease in GEMMs, arguing that resistance to potentially curative therapy can be modeled in GEMMs.

Mice can be used to model the types of cancer seen in people to investigate the effects of cancer therapies, such as radiation. Here, we apply radiation therapy treatments that are able to cure cancer in humans to mice that have cancer of the prostate or colorectum. We show that the mice do not experience many side effects and that the tumours reduce in size, but in some cases show progression after treatment. Our study demonstrates that mice can be used to better understand how human cancers respond to radiation treatment, which can lead to the development of improved treatments and treatment schedules.

Proteomic Profiling of Extracellular Matrix Components from Patient Metastases Identifies Consistently Elevated Proteins for Developing Nanobodies That Target Primary Tumors and Metastases.

Metastases are hard to detect and treat, and they cause most cancer-related deaths. The relative lack of therapies targeting metastases represents a major unmet clinical need. The extracellular matrix (ECM) forms a major component of the tumor microenvironment in both primary and metastatic tumors, and certain ECM proteins can be selectively and abundantly expressed in tumors. Nanobodies against ECM proteins that show selective abundance in metastases have the potential to be used as vehicles for delivery of imaging and therapeutic cargoes. Here, we describe a strategy to develop phage-display libraries of nanobodies against ECM proteins expressed in human metastases, using entire ECM-enriched preparations from triple-negative breast cancer (TNBC) and colorectal cancer metastases to different organs as immunogens. In parallel, LC-MS/MS-based proteomics were used to define a metastasis-associated ECM signature shared by metastases from TNBC and colorectal cancer, and this conserved set of ECM proteins was selectively elevated in other tumors. As proof of concept, selective and high-affinity nanobodies were isolated against an example protein from this signature, tenascin-C (TNC), known to be abundant in many tumor types and to play a role in metastasis. TNC was abundantly expressed in patient metastases and widely expressed across diverse metastatic sites originating from several primary tumor types. Immuno-PET/CT showed that anti-TNC nanobodies bind TNBC tumors and metastases with excellent specificity. We propose that such generic nanobodies against tumors and metastases are promising cancer-agnostic tools for delivery of therapeutics to tumor and metastatic ECM. SIGNIFICANCE: Nanobodies specific for extracellular matrix markers commonly expressed in primary tumors and metastases are promising agents for noninvasive detection of tumors and metastases and potential tools for targeted therapy.

Pyruvate Kinase M1 Suppresses Development and Progression of Prostate Adenocarcinoma.

SIGNIFICANCE: Differential expression of PKM1 and PKM2 impacts prostate tumorigenesis and suggests a potential therapeutic vulnerability in prostate cancer.

Late stage erythroid precursor production is impaired in mice with chronic inflammation.

BACKGROUND: We and others have shown previously that over-expression of hepcidin antimicrobial peptide, independently of inflammation, induces several features of anemia of inflammation and chronic disease, including hypoferremia, sequestration of iron stores and iron-restricted erythropoiesis. Because the iron-restricted erythropoiesis evident in hepcidin transgenic mice differs from the normocytic, normochromic anemia most often observed in anemia of inflammation, we tested the hypothesis that chronic inflammation may contribute additional features to anemia of inflammation which continue to impair erythropoiesis following the acute phase of inflammation in which hepcidin is active. DESIGN AND METHODS: We compared erythropoiesis and iron handling in mice with turpentine-induced sterile abscesses with erythropoiesis and iron handling in hepcidin transgenic mice. We compared erythrocyte indices, expression of genes in the hepcidin regulatory pathway, tissue iron distribution, expression of heme and iron transport genes in splenic macrophages, the phenotype of erythroid maturation and chloromethyl dichlorodihydrofluorescein diacetate, acetyl ester fluorescence. RESULTS: Mice with sterile abscesses exhibited an intense, acute inflammatory phase followed by a mild to moderate chronic inflammatory phase. We found that erythrocytes in mice with sterile abscesses were normocytic and normochromic in contrast to those in hepcidin transgenic mice. We also observed that although hypoferremia resolved in the late phases of inflammation, erythropoiesis remained suppressed, with evidence of inefficient maturation of erythroid precursors in the bone marrow of mice with sterile abscesses. Finally, we observed increased oxidative stress in erythroid progenitors and circulating erythrocytes of mice with sterile abscesses which was not evident in hepcidin transgenic mice. CONCLUSIONS: Our results suggest that chronic inflammation inhibits late stages of erythroid production in the turpentine-induced sterile abscess model and induces features of impaired erythropoiesis which are distinct from those in hepcidin transgenic mice.

Hepcidin antimicrobial peptide transgenic mice exhibit features of the anemia of inflammation.

The anemia of inflammation is an acquired disorder affecting patients with a variety of medical conditions, and it is characterized by changes in iron homeostasis and erythropoiesis. Mounting evidence suggests that hepcidin antimicrobial peptide plays a primary role in the pathogenesis of the anemia of inflammation. To evaluate which features of this anemia can be attributed to hepcidin, we have generated mice carrying a tetracycline-regulated hepcidin transgene. Expression of the hepcidin transgene resulted in down-regulation of endogenous hepcidin mRNA. The transgenic mice developed a mild-to-moderate anemia associated with iron deficiency and iron-restricted erythropoiesis. Similar to the anemia of inflammation, iron accumulated in tissue macrophages, whereas a relative paucity of iron was found in the liver. Circulating erythrocytes in transgenic animals had normal survival rates, but transgenic animals had an impaired response to erythropoietin. Thus, hepcidin transgenic mice recapitulate each of the key features of anemia of inflammation in human patients and serve as a useful model of this prevalent disorder.