and Mutations Promote 4NQO-Initated Head and Neck Tumor Progression and Metastasis in Mice.

The PI3K signaling pathway is frequently mutated in head and neck squamous cell carcinoma (HNSCC), often via gain-of-function (GOF) mutations in the gene. Here, we present novel genetically engineered mouse models (GEMM) carrying a GOF allele (E20) alone or in combination with heterozygous - (p53) mutation with tissue-specific expression to interrogate the role of oncogenic in transformation of upper aerodigestive track epithelium. We demonstrated that the GOF mutation promoted progression of 4-nitroquinoline 1-oxide-induced oral squamous cell carcinoma (OSCC) in both E20 single mutant and E20/p53 double mutant mice, with frequent distal metastasis detected only in E20/p53 GEMM.

Efficient tissue-type specific expression of target genes in a tetracycline-controlled manner from the ubiquitously active Eef1a1 locus.

Using an efficient gene targeting approach, we developed a novel mouse line that expresses the tetracycline-controlled transactivator (tTA) from the constitutively active Eef1a1 locus in a Cre recombinase-inducible manner. The temporally and spatially controlled expression of the EF1-LSL-tTA knockin and activation of tTA-driven responder transgenes was tested using four transgenic lines that express Cre under tissue-specific promoters of the pancreas, mammary gland and other secretory tissues, as well as an interferon-inducible promoter. In all models, the endogenous Eef1a1 promoter facilitated a cell-type-specific activation of target genes at high levels without exogenous enhancer elements.

Aldh1b1 expression defines progenitor cells in the adult pancreas and is required for Kras-induced pancreatic cancer.

The presence of progenitor or stem cells in the adult pancreas and their potential involvement in homeostasis and cancer development remain unresolved issues. Here, we show that mouse centroacinar cells can be identified and isolated by virtue of the mitochondrial enzyme Aldh1b1 that they uniquely express. These cells are necessary and sufficient for the formation of self-renewing adult pancreatic organoids in an Aldh1b1-dependent manner.

Therapeutic effects of an anti-Myc drug on mouse pancreatic cancer.

Background: Pancreatic ductal adenocarcinoma (PDA) is frequently driven by oncogenic KRAS(KRAS*) mutations. We developed a mouse model of KRAS*-induced PDA and, based on genetic results demonstrating that KRAS* tumorigenicity depends on Myc activity, we evaluated the therapeutic potential of an orally administered anti-Myc drug.

Methods: We tested the efficacy of Mycro3, a small-molecule inhibitor of Myc-Max dimerization, in the treatment of mouse PDA (n = 9) and also of xenografts of human pancreatic cancer cell lines (NOD/SCID mice, n = 3-12).

SDF-1 activates papillary label-retaining cells during kidney repair from injury.

The adult kidney contains a population of low-cycling cells that resides in the papilla. These cells retain for long periods S-phase markers given as a short pulse early in life; i.e.

A novel tumour-suppressor function for the Notch pathway in myeloid leukaemia.

Notch signalling is a central regulator of differentiation in a variety of organisms and tissue types. Its activity is controlled by the multi-subunit γ-secretase (γSE) complex. Although Notch signalling can play both oncogenic and tumour-suppressor roles in solid tumours, in the haematopoietic system it is exclusively oncogenic, notably in T-cell acute lymphoblastic leukaemia, a disease characterized by Notch1-activating mutations.

Evasion mechanisms to Igf1r inhibition in rhabdomyosarcoma.

Inhibition of the insulin-like growth factor 1 receptor (Igf1r) is an approach being taken in clinical trials to overcome the dismal outcome for metastatic alveolar rhabdomyosarcoma (ARMS), an aggressive muscle cancer of children and young adults. In our study, we address the potential mechanism(s) of Igf1r inhibitor resistance that might be anticipated for patients. Using a genetically engineered mouse model of ARMS, validated for active Igf1r signaling, we show that the prototypic Igf1r inhibitor NVP-AEW541 can inhibit cell growth and induce apoptosis in vitro in association with decreased Akt and Mapk phosphorylation.

Genetic analysis of type-1 insulin-like growth factor receptor signaling through insulin receptor substrate-1 and -2 in pancreatic beta cells.

Signaling by receptor tyrosine kinases regulates pancreatic β cell function. Inactivation of insulin receptor (InsR), IGF1 receptor (Igf1r), or Irs1 in β cells impairs insulin secretion. Conversely, Irs2 ablation impairs β cell replication.

Insulin receptor and IGF1R are not required for oocyte growth, differentiation, and maturation in mice.

In mammals, insulin and insulin-like growth factors (IGFs: IGF1 and IGF2) act through 2 structurally related receptors, the insulin receptor (INSR) and the type 1 IGF receptor (IGF1R), both of which are expressed in developing oocytes. IGF1 plays an important role in female reproduction, and female Igf1 knockout mice fail to ovulate and are infertile. On the other hand, little is known about the in vivo role of the insulin signaling pathway in oocytes during follicular development, although exposure to insulin or IGF1 in vitro improves oocyte maturation.

Proliferation and migration of label-retaining cells of the kidney papilla.

The kidney papilla contains a population of cells with several characteristics of adult stem cells, including the retention of proliferation markers during long chase periods (i.e., they are label-retaining cells [LRCs]).

CCR7 signalling as an essential regulator of CNS infiltration in T-cell leukaemia.

T-cell acute lymphoblastic leukaemia (T-ALL) is a blood malignancy afflicting mainly children and adolescents. T-ALL patients present at diagnosis with increased white cell counts and hepatosplenomegaly, and are at an increased risk of central nervous system (CNS) relapse. For that reason, T-ALL patients usually receive cranial irradiation in addition to intensified intrathecal chemotherapy.

Igf1r as a therapeutic target in a mouse model of basal-like breast cancer.

Considering the strong association between dysregulated insulin-like growth factor (IGF) signaling and various human cancers, we have used an expedient combination of genetic analysis and pharmacological treatment to evaluate the potential of the type 1 IGF receptor (Igf1r) for targeted anticancer therapy in a mouse model of mammary tumorigenesis. In this particular strain of genetically modified animals, histopathologically heterogeneous invasive carcinomas exhibiting up-regulation of the Igf1r gene developed extremely rapidly by mammary gland-specific overexpression of constitutively active oncogenic Kras* (mutant Kras(G12D)). Immunophenotyping data and expression profiling analyses showed that, except for a minor luminal component, these mouse tumors resembled basal-like human breast cancers.

Irs2 inactivation suppresses tumor progression in Pten+/- mice.

Mutations in the phosphatase and tensin homologue (PTEN)/phosphatidylinositol-3 kinase-alpha (PI3K) signaling pathway are frequently found in human cancer. In addition, Pten(+/-) mice develop tumors in multiple organs because of the activation of the PI3K signaling cascade. Because activation of PI3K signaling leads to feedback inhibition of insulin receptor substrate-2 (IRS2) expression, an upstream activator of PI3K, we therefore anticipated that IRS2 expression would be low in tumors that lack PTEN.

The hormonal action of IGF1 in postnatal mouse growth.

The mammalian insulin-like growth factor 1 (IGF1), which is a member of a major growth-promoting signaling system, is produced by many tissues and functions throughout embryonic and postnatal development in an autocrine/paracrine fashion. In addition to this local action, IGF1 secreted by the liver and circulating in the plasma presumably acts systemically as a classical hormone. However, an endocrine role of IGF1 in growth control was disputed on the basis of the results of a conditional, liver-specific Igf1 gene knockout in mice, which reduced significantly the level of serum IGF1, but did not affect average body weight.

Role of IGF signaling in olfactory sensory map formation and axon guidance.

Olfactory neurons project their axons to spatially invariant glomeruli in the olfactory bulb, forming an ordered pattern of innervation comprising the olfactory sensory map. A mirror symmetry exists within this map, such that neurons expressing a given receptor typically project to one glomerulus on the medial face and one glomerulus on the lateral face of the bulb. The mechanisms underlying an olfactory neuron's choice to project medially versus laterally remain largely unknown, however.

Notch, Myc and breast cancer.

The involvement of Myc in the development of human breast cancer is known for quite some time, but an analogous role of Notch signaling is only now emerging from fragmented pieces of information. Recently, a Notch/Myc relationship in oncogenesis was revealed from a mouse model, in which mammary tumors are induced by the intracellular domain of Notch1 (N1(IC)). In fact, a combination of genetic and molecular data demonstrated that Myc is a direct transcriptional target of Notch1 participating as an indispensable downstream effector in N1(IC)-induced tumorigenic action.

Independent regulation of skeletal growth by Ihh and IGF signaling.

The insulin-like growth factors (IGFs) play a major role in regulating the systemic growth of mammals. However, it is unclear to what extent their systemic and/or local functions act in concert with other local growth factors controlling the sizes of individual organs. We have specifically addressed whether growth control of the skeleton by IGFs interacts genetically with that by Indian hedgehog (Ihh), a locally produced growth signal for the endochondral skeleton.

Myc is a Notch1 transcriptional target and a requisite for Notch1-induced mammary tumorigenesis in mice.

To explore the potential involvement of aberrant Notch1 signaling in breast cancer pathogenesis, we have used a transgenic mouse model. In these animals, mouse mammary tumor virus LTR-driven expression of the constitutively active intracellular domain of the Notch1 receptor (N1(IC)) causes development of lactation-dependent mammary tumors that regress upon gland involution but progress to nonregressing, invasive adenocarcinomas in subsequent pregnancies. Up-regulation of Myc in these tumors prompted a genetic investigation of a potential Notch1/Myc functional relationship in breast carcinogenesis.

Prostatic intraepithelial neoplasia and adenocarcinoma in mice expressing a probasin-Neu oncogenic transgene.

NEU (ERBB2) and other members of the epidermal growth factor receptor (EGFR) family have been implicated in human prostate cancer (CAP) development and progression to an androgen-independent state, but the extent of involvement and precise role of this signaling pathway remain unclear. To begin addressing such open questions in an animal model, we have developed a transgenic line in which an oncogenic Neu cDNA (Neu*) driven by the probasin gene promoter is overexpressed in the mouse prostate and causes development of prostatic intraepithelial neoplasia (PIN) that progresses to invasive carcinoma. Expression profiling using microarrays, which was selectively validated and extended by immunophenotyping of Neu*-induced PIN and CAP, led to the identification of some novel biomarkers and also revealed increased expression of Egfr, Erbb3 and phosphorylated androgen receptor.

Role for Akt3/protein kinase Bgamma in attainment of normal brain size.

Studies of Drosophila and mammals have revealed the importance of insulin signaling through phosphatidylinositol 3-kinase and the serine/threonine kinase Akt/protein kinase B for the regulation of cell, organ, and organismal growth. In mammals, three highly conserved proteins, Akt1, Akt2, and Akt3, comprise the Akt family, of which the first two are required for normal growth and metabolism, respectively. Here we address the function of Akt3.

Modulation of notch signaling elicits signature tumors and inhibits hras1-induced oncogenesis in the mouse mammary epithelium.

Deregulation of Notch signaling, which normally affects a broad spectrum of cell fates, has been implicated in various neoplastic conditions. Here we describe a transgenic mouse model, which demonstrates that expression of a constitutively active form of the Notch1 receptor in the mammary epithelium induces the rapid development of pregnancy/lactation-dependent neoplasms that consistently exhibit a characteristic histopathological pattern. These signature tumors retain the ability to respond to apoptotic stimuli and regress on initiation of mammary gland involution, but eventually appear to progress in subsequent pregnancies to nonregressing malignant adenocarcinomas.

Mosaic analysis of insulin receptor function.

Insulin promotes both metabolism and growth. However, it is unclear whether insulin-dependent growth is merely a result of its metabolic actions. Targeted ablation of insulin receptor (Insr) has not clarified this issue, because of early postnatal lethality.

A mouse model of uterine leiomyosarcoma.

We are using an approach that is based on the cre/loxP recombination process and involves a binary system of Cre-producing and Cre-responding transgenic mice to achieve ubiquitous or tissue-specific expression of oncoproteins. To develop mouse models of tumorigenesis, Cre-producers are mated with responder animals carrying a dormant oncogene targeted into the 3' untranslated region of the locus encoding cytoplasmic beta-actin (actin cassette). Production of oncoprotein from a bicistronic message is accomplished in bitransgenic progeny by Cre-mediated excision of a segment flanked by loxP sites that is located upstream from the oncogenic sequence.

'Designer' tumors in mice.

We have developed and tested successfully a general method based on Cre-mediated recombination that can be used for ubiquitous or tissue-specific expression of protein products, including tumor-inducing oncoproteins. Depending on the specificity of a chosen promoter driving cre expression, tumors develop by design in bitransgenic mouse progeny derived by crossing Cre-producing mice with partners carrying a dormant oncogenic transgene (targeted into the 3' noncoding region of the cytoplasmic beta-actin locus) that becomes functional after excision of a 'floxed' DNA segment. To provide proof-of-principle, we have used as models transgenes encoding the polyomavirus middle T antigen (PVMT) and the T antigens of the SV40 early region (SVER).

Testis determination requires insulin receptor family function in mice.

In mice, gonads are formed shortly before embryonic day 10.5 by the thickening of the mesonephros and consist of somatic cells and migratory primordial germ cells. The male sex-determining process is set in motion by the sex-determining region of the Y chromosome (Sry), which triggers differentiation of the Sertoli cell lineage.