Genetically engineered mouse model of HPV16 E6-E7 with vaginal-cervical intraepithelial neoplasia and decreased immunity

Objective

To construct models of high-risk human papillomavirus (HPV) infection with precancerous lesions or cervical cancer and explore the immune function.

Methods

Using CRISPR/Cas9, the expression vector HPV16-E6-E7-Rosa26 was microinjected into fertilized eggs of C57BL/6 N mice using homologous recombination, and the F0 generation was obtained for reproduction. Then, the formation of precancerous lesions was promoted via intramuscular injection of estradiol. Presence of precancerous cervical-vaginal intraepithelial lesions, Ki67 and p16 expression levels, and CD8+ T cell proportions in the spleen were evaluated.

Results

Two F0 generation mice exhibited correct the homologous recombination. Seven positive mice were identified in the F1 generation. After breeding and mating, 25 homozygous and 11 heterozygous HPV16-E6-E7-engineered mice were obtained from the F2 generation. After estradiol benzoate treatment, the cervical-vaginal epithelium appeared as precancerous lesions with positive Ki67 and p16 expression. The percentage of CD8+ T cells decreased.

Conclusion

HPV16-E6-E7-Rosa26 induced low immune function in mice, and provides a good model for the basic research of the mechanisms of action of HPV infection-associated precancerous lesions or cervical cancer.

Neurofibromatosis type 1-dependent alterations in mouse microglia function are not cell-intrinsic

We previously discovered a sex-by-genotype defect in microglia function using a heterozygous germline knockout mouse model of Neurofibromatosis type 1 (Nf1 ± mice), in which only microglia from male Nf1 ± mice exhibited defects in purinergic signaling. Herein, we leveraged an unbiased proteomic approach to demonstrate that male, but not female, heterozygous Nf1 ± microglia exhibit differences in protein expression, which largely reflect pathways involved in cytoskeletal organization. In keeping with these predicted defects in cytoskeletal function, only male Nf1 ± microglia had reduced process arborization and surveillance capacity. To determine whether these microglial defects were cell autonomous or reflected adaptive responses to Nf1 heterozygosity in other cells in the brain, we generated conditional microglia Nf1-mutant knockout mice by intercrossing Nf1^flox/flox with Cx3cr1-Cre^ER mice (Nf1^flox/wt; Cx3cr1-Cre^ER mice, Nf1^MG ± mice). Surprisingly, neither male nor female Nf1^MG ± mouse microglia had impaired process arborization or surveillance capacity. In contrast, when Nf1 heterozygosity was generated in neurons, astrocytes and oligodendrocytes by intercrossing Nf1^flox/flox with hGFAP-Cre mice (Nf1^flox/wt; hGFAP-Cre mice, Nf1^GFAP ± mice), the microglia defects found in Nf1 ± mice were recapitulated. Collectively, these data reveal that Nf1 ± sexually dimorphic microglia abnormalities are likely not cell-intrinsic properties, but rather reflect a response to Nf1 heterozygosity in other brain cells.

Effects of hyperinsulinemia on pancreatic cancer development and the immune microenvironment revealed through single-cell transcriptomics

BACKGROUND

Hyperinsulinemia is independently associated with increased risk and mortality of pancreatic cancer. We recently reported that genetically reduced insulin production resulted in ~ 50% suppression of pancreatic intraepithelial neoplasia (PanIN) precancerous lesions in mice. However, only female mice remained normoglycemic, and only the gene dosage of the rodent-specific Ins1 alleles was tested in our previous model. Moreover, we did not delve into the molecular and cellular mechanisms associated with modulating hyperinsulinemia.

METHODS

We studied how reduced Ins2 gene dosage affects PanIN lesion development in both male and female Ptf1a^CreER;Kras^LSL-G12D mice lacking the rodent-specific Ins1 gene (Ins1^-/-). We generated control mice having two alleles of the wild-type Ins2 gene (Ptf1a^CreER;Kras^LSL-G12D;Ins1^-/-;Ins2^+/+) and experimental mice having one allele of Ins2 gene (Ptf1a^CreER;Kras^LSL-G12D;Ins1^-/-;Ins2^+/-). We then performed thorough histopathological analyses and single-cell transcriptomics for both genotypes and sexes.

RESULTS

High-fat diet-induced hyperinsulinemia was transiently or modestly reduced in female and male mice, respectively, with only one allele of Ins2. This occurred without dramatically affecting glucose tolerance. Genetic reduction of insulin production resulted in mice with a tendency for less PanIN and acinar-to-ductal metaplasia (ADM) lesions. Using single-cell transcriptomics, we found hyperinsulinemia affected multiple cell types in the pancreas, with the most statistically significant effects on local immune cell types that were highly represented in our sampled cell population. Specifically, hyperinsulinemia modulated pathways associated with protein translation, MAPK-ERK signaling, and PI3K-AKT signaling, which were changed in epithelial cells and subsets of immune cells.

CONCLUSIONS

These data suggest a potential role for the immune microenvironment in hyperinsulinemia-driven PanIN development. Together with our previous work, we propose that mild suppression of insulin levels may be useful in preventing pancreatic cancer by acting on multiple cell types.

In Vitro and In Vivo Tumor Models for the Evaluation of Anticancer Nanoparticles

Multiple studies about tumor biology have revealed the determinant role of the tumor microenvironment in cancer progression, resulting from the dynamic interactions between tumor cells and surrounding stromal cells within the extracellular matrix. This malignant microenvironment highly impacts the efficacy of anticancer nanoparticles by displaying drug resistance mechanisms, as well as intrinsic physical and biochemical barriers, which hamper their intratumoral accumulation and biological activity.Currently, two-dimensional cell cultures are used as the initial screening method in vitro for testing cytotoxic nanocarriers. However, this fails to mimic the tumor heterogeneity, as well as the three-dimensional tumor architecture and pathophysiological barriers, leading to an inaccurate pharmacological evaluation.Biomimetic 3D in vitro tumor models, on the other hand, are emerging as promising tools for more accurately assessing nanoparticle activity, owing to their ability to recapitulate certain features of the tumor microenvironment and thus provide mechanistic insights into nanocarrier intratumoral penetration and diffusion rates.Notwithstanding, in vivo validation of nanomedicines remains irreplaceable at the preclinical stage, and a vast variety of more advanced in vivo tumor models is currently available. Such complex animal models (e.g., genetically engineered mice and patient-derived xenografts) are capable of better predicting nanocarrier clinical efficiency, as they closely resemble the heterogeneity of the human tumor microenvironment.Herein, the development of physiologically more relevant in vitro and in vivo tumor models for the preclinical evaluation of anticancer nanoparticles will be discussed, as well as the current limitations and future challenges in clinical translation.

Model Systems for the Study of Malignant Melanoma

Since the first resection of melanoma by Hunter in 1787, efforts to treat patients with this deadly malignancy have been ongoing. Initial work to understand melanoma biology for therapeutics development began with the employment of isolated cancer cells grown in cell cultures. However, these models lack in vivo interactions with the tumor microenvironment. Melanoma cell line transplantation into suitable animals such as mice has been informative and useful for testing therapeutics as a preclinical model. Injection of freshly isolated patient melanomas into immunodeficient animals has shown the capacity to retain the genetic heterogeneity of the tumors, which is lost during the long-term culture of melanoma cells. Upon advancement of technology, genetically engineered animals have been generated to study the spontaneous development of melanomas in light of newly discovered genetic aberrations associated with melanoma formation. Culturing melanoma cells in a matrix generate tumor spheroids, providing an in vitro environment that promotes the heterogeneity commonplace with human melanoma and displaces the need for animal care facilities. Advanced 3D cultures have been created simulating the structure and cellularity of human skin to permit in vitro testing of therapeutics on melanomas expressing the same phenotype as demonstrated in vivo. This review will discuss these models and their relevance to the study of melanomagenesis, growth, metastasis, and therapy.

Cryopreservation of mouse resources

The cryopreservation of sperm and embryos is useful to efficiently archive valuable resources of genetically engineered mice. Till date, more than 60,000 strains of genetically engineered mice have been archived in mouse banks worldwide. Researchers can request for the archived mouse strains for their research projects. The research infrastructure of mouse banks improves the availability of mouse resources, the productivity of research projects, and the reproducibility of animal experiments. Our research team manages the mouse bank at the Center for Animal Resources and Development in Kumamoto University and continuously develops new techniques in mouse reproductive technology to efficiently improve the system of mouse banking. In this review, we introduce the activities of mouse banks and the latest techniques used in mouse reproductive technology.

Effects of a postnatal Atrx conditional knockout in neurons on autism-like behaviours in male and female mice

BACKGROUND

Alpha-thalassemia/mental retardation, X-linked, or ATRX, is an autism susceptibility gene that encodes a chromatin remodeler. Mutations of ATRX result in the ATR-X intellectual disability syndrome and have been identified in autism spectrum disorder (ASD) patients. The mechanisms by which ATRX mutations lead to autism and autistic-like behaviours are not yet known. To address this question, we generated mice with postnatal Atrx inactivation in excitatory neurons of the forebrain and performed a battery of behavioural assays that assess autistic-like behaviours.

METHODS

Male and female mice with a postnatal conditional ablation of ATRX were generated using the Cre/lox system under the control of the αCaMKII gene promoter. These mice were tested in a battery of behavioural tests that assess autistic-like features. We utilized paradigms that measure social behaviour, repetitive, and stereotyped behaviours, as well as sensory gating. Statistics were calculated by two-way repeated measures ANOVA with Sidak's multiple comparison test or unpaired Student's t tests as indicated.

RESULTS

The behaviour tests revealed no significant differences between Atrx-cKO and control mice. We identified sexually dimorphic changes in odor habituation and discrimination; however, these changes did not correlate with social deficits.

CONCLUSION

The postnatal knockout of Atrx in forebrain excitatory neurons does not lead to autism-related behaviours in male or female mice.

Genotyping Genetically Modified (GM) Mice

Prior to generating a new mouse model, it is important to plan the method that will be used to detect which of the mice generated have the mutation(s) desired. Nearly, all types of mutations may be detected using PCR. However, the choice of primers will differ depending upon the method used to generate the model. Transgenic mice should be genotyped across a unique junction fragment. Targeted ES cells used to generate knock-out or knock-in mice should be genotyped using primers from a unique marker in the construct and a region outside of the construct. Targeting in ES cells can also be detected using a genomic Southern blot. Mice targeted using CRISPR/Cas9 should have the region of interest amplified using PCR, and then be assessed for size changes (for large changes in sequence) by Surveyor Assay (for gene knock-out and point mutations) and/or sequenced to verify the mutation. Each of these models has a unique requirement for genotyping, and failure to understand the requirements can easily lead to loss of the gene in subsequent generations.

Targeting nNOS ameliorates the severe neuropathic pain due to chronic pancreatitis

BACKGROUND

Pain due to pancreatic cancer/PCa or chronic pancreatitis/CP, is notoriously resistant to the strongest pain medications. Here, we aimed at deciphering the specific molecular mediators of pain at surgical-stage pancreatic disease and to discover novel translational targets.

METHODS

We performed a systematic, quantitative analysis of the neurotransmitter/neuroenzmye profile within intrapancreatic nerves of CP and PCa patients. Ex vivo neuronal cultures treated with human pancreatic extracts, conditional genetically engineered knockout mouse models of PCa and CP, and the cerulein-induced CP model were employed to explore the therapeutic potential of the identified targets.

FINDINGS

We identified a unique enrichment of neuronal nitric-oxide-synthase (nNOS) in the pancreatic nerves of CP patients with increasing pain severity. Employment of ex vivo neuronal cultures treated with pancreatic tissue extracts of CP patients, and brain-derived-neurotrophic-factor-deficient (BDNF^+/-) mice revealed neuronal enrichment of nNOS to be a consequence of BDNF loss in the progressively destroyed pancreatic tissue. Mechanistically, nNOS upregulation in sensory neurons was induced by tryptase secreted from perineural mast cells. In a head-to-head comparison of several genetically induced, painless mouse models of PCa (KPC, KC mice) or CP (Ptf1a-Cre;Atg5^fl/fl) against the hypersecretion/cerulein-induced, painful CP mouse model, we show that a similar nNOS enrichment is present in the painful cerulein-CP model, but absent in painless genetic models. Consequently, mice afflicted with painful cerulein-induced CP could be significantly relieved upon treatment with the specific nNOS inhibitor NPLA.

INTERPRETATION

We propose nNOS inhibition as a novel strategy to treat the unbearable pain in CP. FUND: Deutsche Forschungsgemeinschaft/DFG (DE2428/3-1 and 3-2).

RAMP3 deficiency enhances postmenopausal obesity and metabolic disorders

There is a marked increase in the incidence of visceral adiposity and insulin resistance among women following menopause. Adrenomedullin (AM) is an endogenous peptide first identified as a vasodilator, but now known to exert a variety of physiological effects. RAMP3 is a receptor activity-modifying protein that binds to the AM receptor (calcitonin receptor-like receptor). As expression of both AM and RAMP3 is reportedly activated by estrogen, we hypothesized that RAMP3 is crucially involved in the pathophysiology of postmenopausal obesity. To test this idea, we compared the effects of ovariectomy (OVX) and a high-fat diet for 10 weeks (a model of postmenopausal obesity) between RAMP3 knockout (RAMP3-/-) and wild-type mice. RAMP3-/- OVX mice exhibited greater obesity and adipose tissue weight gain as compared to wild-type OVX mice. RAMP3-/- OVX mice also exhibited higher serum insulin levels. In periuterine WAT from RAMP3-/- OVX mice, expression of lipolysis-related factors was lower and expression of inflammation-related factors was higher than in wild-type OVX mice. Hepatic steatosis was also exacerbated in RAMP3-/- OVX. Notably, expression of the membrane-type estrogen receptor GPR30 was downregulated in periuterine WAT from RAMP3-/- OVX mice. These findings raise the possibility that a GPR30-RAMP3 interaction is involved in the pathophysiology of postmenopausal obesity and suggest RAMP3 plays a key role in the regulation of energy metabolism and exerts a hepatoprotective effect in this model of postmenopausal obesity. RAMP3 may thus be a useful therapeutic target for treatment of postmenopausal obesity and metabolic disorders.

The LAT1 inhibitor JPH203 reduces growth of thyroid carcinoma in a fully immunocompetent mouse model

BACKGROUND

The L-type amino acid transporter 1 (LAT1/SLC7A5) transports essential amino acids across the plasma membrane. While LAT1 is overexpressed in a variety of human neoplasms, its expression and its role in thyroid cancer is currently unknown. Anaplastic thyroid carcinoma (ATC) is a highly aggressive malignancy for which no effective therapy exists. The purpose of this study was to explore whether the inhibition of LAT1 in ATC would affect tumor growth both in vitro and in vivo.

METHODS

LAT1 was pharmacologically blocked by JPH203 in human ATC and papillary thyroid cancer (PTC) cell lines. The effects on proliferation and mTORC1 activity were addressed in vitro. A genetically engineered mouse model of ATC was used to address the effect of blocking LAT1 on tumor growth in vivo. SLC7A5 transcription was measured in patient-derived ATC samples to address the clinical relevance of the findings.

RESULTS

LAT1 block by JPH203 reduced proliferation and mTORC1 signaling in human thyroid cancer cell lines. SLC7A5 transcription was upregulated in ATC tissues derived from a genetically engineered mouse model and in ATC samples recovered from patients. JPH203 treatment induced thyroid tumor growth arrest in vivo in a fully immunocompetent mouse model of thyroid cancer. Additionally, analysis of publicly available datasets of thyroid carcinomas revealed that high LAT1 expression is associated with potentially untreatable PTC presenting reduced NIS/SLC5A5 transcription and with ATC.

CONCLUSIONS

These preclinical results show that LAT1 inhibition is a novel therapeutic approach in the context of thyroid cancers, and more interestingly in untreatable thyroid cancers.

Somatic loss of estrogen receptor beta and p53 synergize to induce breast tumorigenesis

Background

Upregulation of estrogen receptor beta (ERβ) in breast cancer cells is associated with epithelial maintenance, decreased proliferation and invasion, and a reduction in the expression of the receptor has been observed in invasive breast tumors. However, proof of an association between loss of ERβ and breast carcinogenesis is still missing.

Methods

To study the role of ERβ in breast oncogenesis, we generated mouse conditional mutants with specific inactivation of ERβ and p53 in the mammary gland epithelium. For epithelium-specific knockout of ERβ and p53, ERβ^F/F and p53^F/F mice were crossed to transgenic mice that express the Cre recombinase under the control of the human keratin 14 promoter.

Results

Somatic loss of ERβ significantly accelerated formation of p53-deficient mammary tumors. Loss of the receptor also resulted in the development of less differentiated carcinomas with stronger spindle cell morphology and decreased expression of luminal epithelial markers.

Conclusions

Our results show that synergism between ERβ and p53 inactivation functions to determine important aspects of breast oncogenesis and cancer progression.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-017-0872-z) contains supplementary material, which is available to authorized users.

Advances in rodent models of human esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is a common form of malignant disease. Appropriate animal models recapitulating human cancers, which are powerful not only for the elucidation of in vivo process and relevant mechanisms of the diseases but also for the evaluation of efficacy and safety of new drugs and management concepts, are critical for the success of translational research. In this context, compared with other malignancies, the present situation for human ESCC that novel discoveries for either diagnostic markers or therapeutic targets as well as the clinical application are out of step (laggard) is largely attributed to the lack of suitable in vivo animal model for this human disease. This article provides an overview of the currently available animal models established for human ESCC, encompassing chemically induced and genetically engineered rodents. Genetically engineered mice coupling induction with 4-nitroquinoline-1-oxide (4NQO) are discussed in more detail.

Animal models of liver cancer: progress and prospects

Primary liver cancer remains one of the most lethal malignancies worldwide. As this disease is lethal in most cases, research has to be done to improve our understanding of the disease and to offer insights for possible treatment options. Animal models have been widely used in the research of primary liver cancer. Here, we review the progress and prospects for the development of animal models of primary liver cancer, highlighting the best candidates for future preclinical investigations.

Mouse models in liver cancer research: A review of current literature

Primary liver cancer remains one of the most lethal malignancies worldwide. Due to differences in prevalence of etiological factors the incidence of primary liver cancer varies among the world, with a peak in East-Asia. As this disease is still lethal in most of the cases, research has to be done to improve our understanding of the disease, offering insights for possible treatment options. For this purpose, animal models are widely used, especially mouse models. In this review, we describe the different types of mouse models used in liver cancer research, with emphasis on genetically engineered mice used in this field. We focus on hepatocellular carcinoma (HCC), as this is by far the most common type of primary liver cancer, accounting for 70%-85% of cases.