Embryonic Lethality in Homozygous Human Her-2 Transgenic Mice Due to Disruption of the Pds5b Gene

The widely used Ucp1-CreEvdr transgene elicits complex developmental and metabolic phenotypes

Bacterial artificial chromosome transgenic models, including most Cre-recombinases, enable potent interrogation of gene function in vivo but require rigorous validation as limitations emerge. Due to its high relevance to metabolic studies, we performed comprehensive analysis of the Ucp1-CreEvdr line which is widely used for brown fat research. Hemizygotes exhibited major brown and white fat transcriptomic dysregulation, indicating potential altered tissue function. Ucp1-CreEvdr homozygotes also show high mortality, growth defects, and craniofacial abnormalities. Mapping the transgene insertion site revealed insertion in chromosome 1 accompanied by large genomic alterations disrupting several genes expressed in a range of tissues. Notably, Ucp1-CreEvdr transgene retains an extra Ucp1 gene copy that may be highly expressed under high thermogenic burden. Our multi-faceted analysis highlights a complex phenotype arising from the presence of the Ucp1-CreEvdr transgene independently of the intended genetic manipulations. Overall, comprehensive validation of transgenic mice is imperative to maximize discovery while mitigating unexpected, off-target effects.

Rapid and precise genotyping of transgene zygosity in mice using an allele-specific method

Precise determination of transgene zygosity is essential for use of transgenic mice in research. Because integration loci of transgenes are usually unknown due to their random insertion, assessment of transgene zygosity remains a challenge. Current zygosity genotyping methods (progeny testing, qPCR, and NGS-computational biology analysis) are time consuming, prone to error or technically challenging. Here, we developed a novel method to determine transgene zygosity requiring no knowledge of transgene insertion loci. This method applies allele-specific restriction enzyme digestion of PCR products (RE/PCR) to rapidly and reliably quantify transgene zygosity. We demonstrate the applicability of this method to three transgenic strains of mice (Atm TgC3001L, Nes-Cre, and Syn1-Cre) harboring a unique restriction enzyme site on either the transgene or its homologous sequence in the mouse genome. This method is as accurate as the gold standard of progeny testing but requires 2 d instead of a month or more. It is also exceedingly more accurate than the most commonly used approach of qPCR quantification. Our novel method represents a significant technical advance in determining transgene zygosities in mice.

ASIS-Seq: Transgene Insertion Site Mapping by Nanopore Adaptive Sampling

Generation of transgenic mice by direct microinjection of foreign DNA into fertilized ova has become a routine technique in biomedical research. It remains an essential tool for studying gene expression, developmental biology, genetic disease models, and their therapies. However, the random integration of foreign DNA into the host genome that is inherent to this technology can lead to confounding effects associated with insertional mutagenesis and transgene silencing. Locations of most transgenic lines remain unknown because the methods are often burdensome (Nicholls et al., G3: Genes Genomes Genetics 9:1481-1486, 2019) or have limitations (Goodwin et al., Genome Research 29:494-505, 2019). Here, we present a method that we call Adaptive Sampling Insertion Site Sequencing (ASIS-Seq) to locate transgene integration sites using targeted sequencing on Oxford Nanopore Technologies' (ONT) sequencers. ASIS-Seq requires only about 3 ug of genomic DNA, 3 hours of hands-on sample preparation time, and 3 days of sequencing time to locate transgenes in a host genome.

Concatenation of Transgenic DNA: Random or Orchestrated?

Generation of transgenic organisms by pronuclear microinjection has become a routine procedure. However, while the process of DNA integration in the genome is well understood, we still do not know much about the recombination between transgene molecules that happens in the first moments after DNA injection. Most of the time, injected molecules are joined together in head-to-tail tandem repeats-the so-called concatemers. In this review, we focused on the possible concatenation mechanisms and how they could be studied with genetic reporters tracking individual copies in concatemers. We also discuss various features of concatemers, including palindromic junctions and repeat-induced gene silencing (RIGS). Finally, we speculate how cooperation of DNA repair pathways creates a multicopy concatenated insert.

A Histone Deacetylase Inhibitor, Panobinostat, Enhances Chimeric Antigen Receptor T-cell Antitumor Effect Against Pancreatic Cancer

PURPOSE

In this article, we describe a combination chimeric antigen receptor (CAR) T-cell therapy that eradicated the majority of tumors in two immunocompetent murine pancreatic cancer models and a human pancreatic cancer xenograft model.

EXPERIMENTAL DESIGN

We used a dual-specific murine CAR T cell that expresses a CAR against the Her2 tumor antigen, and a T-cell receptor (TCR) specific for gp100. As gp100 is also known as pMEL, the dual-specific CAR T cells are thus denoted as CARaMEL cells. A vaccine containing live vaccinia virus coding a gp100 minigene (VV-gp100) was administered to the recipient mice to stimulate CARaMEL cells. The treatment also included the histone deacetylase inhibitor panobinostat (Pano).

RESULTS

The combination treatment enabled significant suppression of Her2⁺ pancreatic cancers leading to the eradication of the majority of the tumors. Besides inducing cancer cell apoptosis, Pano enhanced CAR T-cell gene accessibility and promoted CAR T-cell differentiation into central memory cells. To test the translational potential of this approach, we established a method to transduce human T cells with an anti-Her2 CAR and a gp100-TCR. The exposure of the human T cells to Pano promoted a T-cell central memory phenotype and the combination treatment of human CARaMEL cells and Pano eradicated human pancreatic cancer xenografts in mice.

CONCLUSIONS

We propose that patients with pancreatic cancer could be treated using a scheme that contains dual-specific CAR T cells, a vaccine that activates the dual-specific CAR T cells through their TCR, and the administration of Pano.

Diversity Outbred Mice Reveal the Quantitative Trait Locus and Regulatory Cells of HER2 Immunity

The genetic basis and mechanisms of disparate antitumor immune response was investigated in Diversity Outbred (DO) F1 mice that express human HER2. DO mouse stock samples nearly the entire genetic repertoire of the species. We crossed DO mice with syngeneic HER2 transgenic mice to study the genetics of an anti-self HER2 response in a healthy outbred population. Anti-HER2 IgG was induced by Ad/E2TM or naked pE2TM, both encoding HER2 extracellular and transmembrane domains. The response of DO F1 HER2 transgenic mice was remarkably variable. Still, immune sera inhibited HER2+ SKBR3 cell survival in a dose-dependent fashion. Using DO quantitative trait locus (QTL) analysis, we mapped the QTL that influences both total IgG and IgG2(a/b/c) Ab response to either Ad/E2TM or pE2TM. QTL from these four datasets identified a region in chromosome 17 that was responsible for regulating the response. A/J and NOD segments of genes in this region drove elevated HER2 Ig levels. This region is rich in MHC-IB genes, several of which interact with inhibitory receptors of NK cells. (B6xA/J)F1 and (B6xNOD)F1 HER2 transgenic mice received Ad/E2TM after NK cell depletion, and they produced less HER2 IgG, demonstrating positive regulatory function of NK cells. Depletion of regulatory T cells enhanced response. Using DO QTL analysis, we show that MHC-IB reactive NK cells exert positive influence on the immunity, countering negative regulation by regulatory T cells. This new, to our knowledge, DO F1 platform is a powerful tool for revealing novel immune regulatory mechanisms and for testing new interventional strategies.

Enhancing chimeric antigen receptor T-cell immunotherapy against cancer using a nanoemulsion-based vaccine targeting cross-presenting dendritic cells

Objectives

Adoptive transfer of chimeric antigen receptor (CAR)-modified T cells is a form of cancer immunotherapy that has achieved remarkable efficacy in patients with some haematological cancers. However, challenges remain in CAR T-cell treatment of solid tumours because of tumour-mediated immunosuppression.

Methods

We have demonstrated that CAR T-cell stimulation through T-cell receptors (TCRs) in vivo can generate durable responses against solid tumours in a variety of murine models. Since Clec9A-targeting tailored nanoemulsion (Clec9A-TNE) vaccine enhances antitumour immune responses through selective activation of Clec9A⁺ cross-presenting dendritic cells (DCs), we hypothesised that Clec9A-TNE could prime DCs for antigen presentation to CAR T cells through TCRs and thus improve CAR T-cell responses against solid tumours. To test this hypothesis, we used CAR T cells expressing transgenic TCRs specific for ovalbumin (OVA) peptides SIINFEKL (CAROTI) or OVA_323-339 (CAROTII).

Results

We demonstrated that the Clec9A-TNEs encapsulating full-length recombinant OVA protein (OVA-Clec9A-TNE) improved CAROT T-cell proliferation and inflammatory cytokine secretion in vitro. Combined treatment using the OVA-Clec9A-TNE and CAROT cells resulted in durable responses and some rejections of tumours in immunocompetent mice. Tumour regression was accompanied by enhanced CAROT cell proliferation and infiltration into the tumours.

Conclusion

Our study presents Clec9A-TNE as a prospective avenue to enhance CAR T-cell efficacy for solid cancers.

PDS5B regulates cell proliferation and motility via upregulation of Ptch2 in pancreatic cancer cells

Pds5b (precocious dissociation of sisters 5B) is involved in both tumorigenesis and cancer progression; however, the functions and molecular mechanisms of Pds5b in pancreatic cancer (PC) are unknown. Several approaches were conducted to investigate the molecular basis of Pds5b-related PC progression, including transfection, MTT, FACS, western blotting, wound healing assay, transwell chamber invasion assay, and immunohistochemical methods. Pds5b overexpression inhibited cell growth and induced apoptosis, whereas the inhibition of Pds5b promoted growth of PC cells. Moreover, Pds5b overexpression inhibited cell migration and invasion, while the downregulation of Pds5b enhanced cell motility. Furthermore, reduced Pds5b expression was associated with survival in PC patients. Mechanistically, Pds5b positively regulated the expression of Ptch2 to influence the Sonic hedgehog signaling pathway. Consistently, Ptch2 downregulation enhanced cell growth, migration, and invasion, while inhibiting cell apoptosis. Notably, the downregulation of Ptch2 abolished Pds5b-mediated anti-tumor activity in PC cells. Strikingly, Pds5b expression was positively associated with levels of Ptch2 in PC patient samples, suggesting that the Pds5b/Ptch2 axis regulates cell proliferation and invasion in PC cells. Our findings indicate that targeting Pds5b and Ptch2 may represent a novel therapeutic approach for PC.

An HER2 DNA vaccine with evolution-selected amino acid substitutions reveals a fundamental principle for cancer vaccine formulation in HER2 transgenic mice

Enhancement of endogenous immunity to tumor-associated self-antigens and neoantigens is the goal of preventive vaccination. Toward this goal, we compared the efficacy of the following HER2 DNA vaccine constructs: vaccines encoding wild-type HER2, hybrid HER2 vaccines consisting of human HER2 and rat Neu, HER2 vaccines with single residue substitutions and a novel human HER2 DNA vaccine, ph(es)E2TM. ph(es)E2TM was designed to contain five evolution-selected substitutions: M198V, Q398R, F425L, H473R and A622T that occur frequently in 12 primate HER2 sequences. These ph(es)E2TM substitutions score 0 to 1 in blocks substitutions matrix (BLOSUM), indicating minimal biochemical alterations. h(es)E2TM recombinant protein is recognized by a panel of anti-HER2 mAbs, demonstrating the preservation of HER2 protein structure. Compared to native human HER2, electrovaccination of HER2 transgenic mice with ph(es)E2TM induced a threefold increase in HER2-binding antibody (Ab) and elevated levels of IFNγ-producing T cells. ph(es)E2TM, but not pE2TM immune serum, recognized HER2 peptide p95 ₃₅₅LPESFDGDPASNTAP₃₆₉, suggesting a broadening of epitope recognition induced by the minimally modified HER2 vaccine. ph(es)E2TM vaccination reduced tumor growth more effectively than wild-type HER2 or HER2 vaccines with more extensive modifications. The elevation of tumor immunity by ph(es)E2TM vaccination would create a favorable tumor microenvironment for neoantigen priming, further enhancing the protective immunity. The fundamental principle of exploiting evolution-selected amino acid substitutions is novel, effective and applicable to vaccine development in general.

A role for multiple chimeric antigen receptor-expressing leukocytes in antigen-specific responses to cancer

While adoptive immunotherapy using chimeric antigen receptor (CAR)-modified T cells can induce remission of some tumors, the role of other CAR-modified leukocytes is not well characterized. In this study, we characterize the function of leukocytes including natural killer (NK) cells, macrophages and CAR T cells from transgenic mice expressing a CAR under the control of the pan-hematopoietic promoter, vav, and determine the ability of these mice to respond to ERB expressing tumors. We demonstrate the anti-tumor functions of leukocytes, including antigen specific cytotoxicity and cytokine secretion. The adoptive transfer of CAR T cells provided a greater survival advantage in the E0771ERB tumor model than their wildtype (WT) counterparts. In addition, CAR NK cells and CAR T cells also mediated increased survival in the RMAERB tumor model. When challenged with Her2 expressing tumors, F38 mice were shown to mount an effective immune response, resulting in tumor rejection and long-term survival. This was shown to be predominantly dependent on both CD8⁺ T cells and NK cells. However, macrophages and CD4⁺ T cells were also shown to contribute to this response. Overall, this study highlights the use of the vav-CAR mouse model as a unique tool to determine the anti-tumor function of various immune subsets, either alone or when acting alongside CAR T cells in adoptive immunotherapy.

Effect of Fu-Zheng-Xiao-Liu Granules on Expression of Human Epidermal Growth Factor Receptor 2 (HER-2) and Proliferation and Apoptosis of Breast Cancer Cell Line SKBR-3

Background

Previous research showed that granulized Fu-Zheng-Xiao-Liu has a significant effect on breast cancer. However, it remains unclear whether HER-2 plays a role in this anti-cancer effect.

Material/Methods

Serum of male SD rats administered Fu-Zheng-Xiao-Liu granules (SF) was prepared and used to treat HER-2 positive breast cancer cell line SKBR-3. PBS and herceptin were used as negative and positive controls, respectively. MTT was used to detect the proliferation of SKBR-3 cells. Flow cytometry was used to measure the apoptosis of SKBR-3 cells. Western blot and immunofluorescence were used to measure the expression change of HER-2.

Results

Serum of male SD rats administered Fu-Zheng-Xiao-Liu granules had significantly reduced HER-2 expression at both mRNA level and protein level, significantly inhibited proliferation of SKBR-3 cells, and significantly increased apoptosis of SKBR-3 cells, compared to that of the blank control group or serum control group.

Conclusions

Fu-Zheng-Xiao-Liu granules affect proliferation and apoptosis through inhibition of HER-2 transcription and translation, providing an experimental basis for further study of the mechanism by which Fu-Zheng-Xiao-Liu granules affect breast cancer.

Dual-specific Chimeric Antigen Receptor T Cells and an Indirect Vaccine Eradicate a Variety of Large Solid Tumors in an Immunocompetent, Self-antigen Setting

Purpose: While adoptive transfer of T cells bearing a chimeric antigen receptor (CAR) can eliminate substantial burdens of some leukemias, the ultimate challenge remains the eradication of large solid tumors for most cancers. We aimed to develop an immunotherapy approach effective against large tumors in an immunocompetent, self-antigen preclinical mouse model.Experimental Design: In this study, we generated dual-specific T cells expressing both a CAR specific for Her2 and a TCR specific for the melanocyte protein (gp100). We used a regimen of adoptive cell transfer incorporating vaccination (ACTIV), with recombinant vaccinia virus expressing gp100, to treat a range of tumors including orthotopic breast tumors and large liver tumors.Results: ACTIV therapy induced durable complete remission of a variety of Her2⁺ tumors, some in excess of 150 mm², in immunocompetent mice expressing Her2 in normal tissues, including the breast and brain. Vaccinia virus induced extensive proliferation of T cells, leading to massive infiltration of T cells into tumors. Durable tumor responses required the chemokine receptor CXCR3 and exogenous IL2, but were independent of IFNγ. Mice were resistant to tumor rechallenge, indicating immune memory involving epitope spreading. Evidence of limited neurologic toxicity was observed, associated with infiltration of cerebellum by T cells, but was only transient.Conclusions: This study supports a view that it is possible to design a highly effective combination immunotherapy for solid cancers, with acceptable transient toxicity, even when the target antigen is also expressed in vital tissues. Clin Cancer Res; 23(10); 2478-90. ©2016 AACR.