CD47-Dependent Regulation of Immune Checkpoint Gene Expression and MYCN mRNA Splicing in Murine CD8 and Jurkat T Cells.

Elevated expression of CD47 in some cancers is associated with poor survival related to its function as an innate immune checkpoint when expressed on tumor cells. In contrast, elevated CD47 expression in cutaneous melanomas is associated with improved survival. Previous studies implicated protective functions of CD47 expressed by immune cells in the melanoma tumor microenvironment. RNA sequencing analysis of responses induced by CD3 and CD28 engagement on wild type and CD47-deficient Jurkat T lymphoblast cells identified additional regulators of T cell function that were also CD47-dependent in mouse CD8 T cells. MYCN mRNA expression was upregulated in CD47-deficient cells but downregulated in CD47-deficient cells following activation. CD47 also regulated alternative splicing that produces two N-MYC isoforms. The CD47 ligand thrombospondin-1 inhibited expression of these MYCN mRNA isoforms, as well as induction of the oncogenic decoy MYCN opposite strand (MYCNOS) RNA during T cell activation. Analysis of mRNA expression data for melanomas in The Cancer Genome Atlas identified a significant coexpression of MYCN with CD47 and known regulators of CD8 T cell function. Thrombospondin-1 inhibited the induction of TIGIT, CD40LG, and MCL1 mRNAs following T cell activation in vitro. Increased mRNA expression of these T cell transcripts and MYCN in melanomas was associated with improved overall survival.

Naturally Acquired Mouse Kidney Parvovirus Infection Produces a Persistent Interstitial Nephritis in Immunocompetent Laboratory Mice.

Mouse kidney parvovirus (MKPV), also known as murine chapparvovirus (MuCPV), is an emerging, highly infectious agent that has been isolated from laboratory and wild mouse populations. In immunocompromised mice, MKPV produces severe chronic interstitial nephropathy and renal failure within 4 to 5 months of infection. However, the course of disease, severity of histologic lesions, and viral shedding are uncertain for immunocompetent mice. We evaluated MKPV infections in CD-1 and Swiss Webster mice, 2 immunocompetent stocks of mice. MKPV-positive CD-1 mice (n = 30) were identified at approximately 8 weeks of age by fecal PCR (polymerase chain reaction) and were subsequently housed individually for clinical observation and diagnostic sampling. Cage swabs, fecal pellets, urine, and blood were evaluated by PCR at 100 and 128 days following the initial positive test, which identified that 28 of 30 were persistently infected and 24 of these were viremic at 100 days. Histologic lesions associated with MKPV in CD-1 (n = 31) and Swiss mice (n = 11) included lymphoplasmacytic tubulointerstitial nephritis with tubular degeneration. Inclusion bodies were rare; however, intralesional MKPV mRNA was consistently detected via in situ hybridization within tubular epithelial cells of the renal cortex and within collecting duct lumina. In immunocompetent CD-1 mice, MKPV infection resulted in persistent shedding of virus for up to 10 months and a mild tubulointerstitial nephritis, raising concerns that this virus could produce study variations in immunocompetent models. Intranuclear inclusions were not a consistent feature of MKPV infection in immunocompetent mice.

Potential role of cervicovaginal extracellular particles in diagnosis of endometriosis.

BACKGROUND: Macaques are an excellent model for many human diseases, including reproductive diseases such as endometriosis. A long-recognized need for early biomarkers of endometriosis has not yet resulted in consensus. While biomarker studies have examined many bodily fluids and targets, cervicovaginal secretions have been relatively under-investigated. Extracellular vesicles (EVs, including exosomes and microvesicles) are found in every biofluid examined, carry cargo including proteins and RNA, and may participate in intercellular signaling. Little is known about EVs in the cervicovaginal compartment, including the effects of reproductive tract disease on quantity and quality of EVs. CASE PRESENTATION: In September 2014, a 9-year-old rhesus macaque was diagnosed with endometriosis at The Johns Hopkins University School of Medicine. Ultrasound-guided fine needle aspiration of a cyst and subsequent laparotomy confirmed diagnosis. The animal was sent to necropsy following euthanasia for humane reasons. Perimortem vaginal swabs and cervicovaginal lavages were obtained. Using a combination of methods, including ultracentrifugation and NanoSight visualization technology, approximate numbers of EVs from each sample were calculated and compared to populations of EVs from other, reproductively normal macaques. Fewer EVs were recovered from the endometriosis samples as compared with those from reproductively healthy individuals. CONCLUSION: To our knowledge, this is the first examination of EVs in primate cervicovaginal secretions, including those of a macaque with endometriosis. This case study suggests that additional research is justified to determine whether quantification of EVs-or their molecular cargo-in cervicovaginal lavage and vaginal swabs may provide a novel, relatively non-invasive diagnostic for primate endometrial disease or other reproductive tract diseases.

Enhancing standard of care chemotherapy efficacy using DNA-dependent protein kinase (DNA-PK) inhibition in preclinical models of Ewing sarcoma.

Disruption of DNA damage repair via impaired homologous recombination is characteristic of Ewing sarcoma (EWS) cells. We hypothesize that this disruption results in increased reliance on non-homologous end joining (NHEJ) to repair DNA damage. In this study, we investigated if pharmacological inhibition of the enzyme responsible for NHEJ, the DNA-PK holoenzyme, alters the response of EWS cells to genotoxic standard of care chemotherapy. We used analyses of cell viability and proliferation to investigate the effects of clinical DNA-PK inhibitors (DNA-PKi) in combination with six therapeutic or experimental agents for EWS. We performed calculations of synergy using the Loewe Additivity Model. Immunoblotting evaluated treatment effects on DNA-PK, DNA damage, and apoptosis. Flow cytometric analyses evaluated effects on cell cycle and fate. We used orthotopic xenograft models to interrogate tolerability, drug mechanism, and efficacy in vivo. DNA-PKi demonstrated on-target activity, reducing phosphorylated DNA-PK levels in EWS cells. DNA-PKi sensitized EWS cell lines to agents that function as topoisomerase 2 (TOP2) poisons and enhanced the DNA damage induced by TOP2 poisons. Nanomolar concentrations of single agent TOP2 poisons induced G2M arrest and little apoptotic response, while adding DNA-PKi mediated apoptosis. In vivo, the combination of AZD-7648 and etoposide had limited tolerability but resulted in enhanced DNA damage, apoptosis, and EWS tumor shrinkage. The combination of DNA-PKi with standard of care TOP2 poisons in EWS models is synergistic, enhances DNA damage and cell death, and may form the basis of a promising future therapeutic strategy for EWS.

Chemoprevention utility of silibinin and Cdk4 pathway inhibition in Apc(-/+) mice.

BACKGROUND: Colorectal cancer (CRC) is the second leading cause of death from cancer in the United States. Colorectal cancers have a prolonged latency following initiation that may span decades providing ample time for implementing a chemoprevention strategy that could block or reverse the progression to CRC. Cdk4 pathway alterations have been linked to a number of cancers including CRC. In these experiments we focused on the Cdk4 pathway and its role in intestinal tumorigenesis as a possible target in chemoprevention strategies. METHODS: We evaluated the effect of Cdk4 blockade on the prevention of intestinal tumor formation by crossing Cdk4(-/-) mice to Apc(-/+) mice. In addition, we tested the effect of the dietary compound silibinin on the Cdk4 pathway in Apc(-/+) mice and HT-29 colon cancer cells in culture. RESULTS: Cdk4(-/-) mice backcrossed to Apc(-/+) mice reduced intestinal adenoma formation compared to Apc(-/+) controls. Silibinin effectively targeted the Cdk4 pathway causing hypophosphorylation of the retinoblastoma protein, inhibited cell growth, and induced apoptosis. As a result silibinin blocked the development of intestinal adenomas by 52% in this genetic model (Apc(-/+) mice) of early events in colorectal cancer formation. No toxic abnormalities were detected in mice which received silibinin. CONCLUSIONS: Modification of the Cdk4 pathway using a natural plant-derived compound such as silibinin may be a useful chemopreventive strategy for colorectal carcinomas.

Anti-Cancer Activity of Verteporfin in Cholangiocarcinoma.

Cholangiocarcinoma (CCA) is a heterogenous malignancy that arises from the biliary epithelium and has a poor clinical prognosis. The Hippo/yes-associated protein (YAP) pathway has been reported to affect various aspects of tumorigenesis, with high expression of YAP1 being negatively associated with survival in CCA patients. Thus, we investigated the antitumoral effect of verteporfin, a YAP1 pathway inhibitor, in YAP1/AKT hydrodynamic tail vein injected murine models. We also used flow cytometry and single-cell RNA sequencing (scRNA-seq) to analyze the change in the immune cell profile and malignant cell stemness following verteporfin treatment. Our results demonstrated reduced liver weight and tumor formation in verteporfin-treated groups compared to that of a vehicle-treated group. Immune cell profiling through flow cytometry showed that relative to the vehicle, verteporfin induced a higher ratio of tumor-associated macrophage (TAM) M1/M2 and increased the percentage of activated CD8 T cell population (CD8+CD25+ and CD8+CD69+). scRNA-seq analysis showed significantly increased TAM M1 populations following verteporfin treatment and decreased proportions of stem-like cells within the malignant cell population. In summary, this study indicates that in CCA YAP/AKT murine models, verteporfin reduces tumorigenesis by polarizing anti-tumoral TAM and activating CD8 T cells and decreasing stem-like malignant cell proportions in the tumor microenvironment.

Inhibition of NAD+-Dependent Metabolic Processes Induces Cellular Necrosis and Tumor Regression in Rhabdomyosarcoma Models.

PURPOSE: Deregulated metabolism in cancer cells represents a vulnerability that may be therapeutically exploited to benefit patients. One such target is nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme in the NAD+ salvage pathway. NAMPT is necessary for efficient NAD+ production and may be exploited in cells with increased metabolic demands. We have identified NAMPT as a dependency in rhabdomyosarcoma (RMS), a malignancy for which novel therapies are critically needed. Here we describe the effect of NAMPT inhibition on RMS proliferation and metabolism in vitro and in vivo. EXPERIMENTAL DESIGN: Assays of proliferation and cell death were used to determine the effects of pharmacologic NAMPT inhibition in a panel of ten molecularly diverse RMS cell lines. Mechanism of the clinical NAMPTi OT-82 was determined using measures of NAD+ and downstream NAD+-dependent functions, including energy metabolism. We used orthotopic xenograft models to examine tolerability, efficacy, and drug mechanism in vivo. RESULTS: Across all ten RMS cell lines, OT-82 depleted NAD+ and inhibited cell growth at concentrations ≤1 nmol/L. Significant impairment of glycolysis was a universal finding, with some cell lines also exhibiting diminished oxidative phosphorylation. Most cell lines experienced profound depletion of ATP with subsequent irreversible necrotic cell death. Importantly, loss of NAD and glycolytic activity were confirmed in orthotopic in vivo models, which exhibited complete tumor regressions with OT-82 treatment delivered on the clinical schedule. CONCLUSIONS: RMS is highly vulnerable to NAMPT inhibition. These findings underscore the need for further clinical study of this class of agents for this malignancy.

Telomere fusion to chromosome breaks reduces oncogenic translocations and tumour formation.

Telomeres protect chromosome ends from fusion, degradation and recombination. Loss of telomere function has opposite effects on tumorigenesis: apoptosis, which inhibits tumour growth, and genomic instability, which accelerates tumour formation. Here we describe a new mechanism by which short telomeres inhibit tumorigenesis through interference with oncogenic translocations. In mice that are null for both ataxia-telangiectasia-mutated (Atm) and telomerase RNA (mTR), the first generation (G1) Atm-/- mTR-/- mice have a lower rate of tumour formation than Atm-/- mTR+/+ mice. These Atm-/- mTR-/- G1 tumours show no increase in either apoptosis or overall genomic instability. Strikingly, the tumours show a high fraction of translocations containing telomere signals at the translocation junctions. Translocations of the T-cell receptors on chromosome 14, which initiate tumorigenesis, were interrupted by fusion with telomeres. Telomere repeats were also detected at the translocation junctions in pre-malignant thymocytes. We propose that telomere fusion to DNA double-strand breaks competes with the generation of oncogenic translocations and thus reduces tumour formation.

TNIK Is a Therapeutic Target in Lung Squamous Cell Carcinoma and Regulates FAK Activation through Merlin.

Lung squamous cell carcinoma (LSCC) is the second most prevalent type of lung cancer. Despite extensive genomic characterization, no targeted therapies are approved for the treatment of LSCC. Distal amplification of the 3q chromosome is the most frequent genomic alteration in LSCC, and there is an urgent need to identify efficacious druggable targets within this amplicon. We identify the protein kinase TNIK as a therapeutic target in LSCC. TNIK is amplified in approximately 50% of LSCC cases. TNIK genetic depletion or pharmacologic inhibition reduces the growth of LSCC cells in vitro and in vivo. In addition, TNIK inhibition showed antitumor activity and increased apoptosis in established LSCC patient-derived xenografts. Mechanistically, we identified the tumor suppressor Merlin/NF2 as a novel TNIK substrate and showed that TNIK and Merlin are required for the activation of focal adhesion kinase. In conclusion, our data identify targeting TNIK as a potential therapeutic strategy in LSCC. SIGNIFICANCE: Targeted therapies have not yet been approved for the treatment of LSCC, due to lack of identification of actionable cancer drivers. We define TNIK catalytic activity as essential for maintaining LSCC viability and validate the antitumor efficacy of TNIK inhibition in preclinical models of LSCC.This article is highlighted in the In This Issue feature, p. 1307.

TFE3 Xp11.2 Translocation Renal Cell Carcinoma Mouse Model Reveals Novel Therapeutic Targets and Identifies GPNMB as a Diagnostic Marker for Human Disease.

Renal cell carcinoma (RCC) associated with Xp11.2 translocation (TFE3-RCC) has been recently defined as a distinct subset of RCC classified by characteristic morphology and clinical presentation. The Xp11 translocations involve the TFE3 transcription factor and produce chimeric TFE3 proteins retaining the basic helix-loop-helix leucine zipper structure for dimerization and DNA binding suggesting that chimeric TFE3 proteins function as oncogenic transcription factors. Diagnostic biomarkers and effective forms of therapy for advanced cases of TFE3-RCC are as yet unavailable. To facilitate the development of molecular based diagnostic tools and targeted therapies for this aggressive kidney cancer, we generated a translocation RCC mouse model, in which the PRCC-TFE3 transgene is expressed specifically in kidneys leading to the development of RCC with characteristic histology. Expression of the receptor tyrosine kinase Ret was elevated in the kidneys of the TFE3-RCC mice, and treatment with RET inhibitor, vandetanib, significantly suppressed RCC growth. Moreover, we found that Gpnmb (Glycoprotein nonmetastatic B) expression was notably elevated in the TFE3-RCC mouse kidneys as seen in human TFE3-RCC tumors, and confirmed that GPNMB is the direct transcriptional target of TFE3 fusions. While GPNMB IHC staining was positive in 9/9 cases of TFE3-RCC, Cathepsin K, a conventional marker for TFE3-RCC, was positive in only 67% of cases. These data support RET as a potential target and GPNMB as a diagnostic marker for TFE3-RCC. The TFE3-RCC mouse provides a preclinical in vivo model for the development of new biomarkers and targeted therapeutics for patients affected with this aggressive form of RCC. IMPLICATIONS: Key findings from studies with this preclinical mouse model of TFE3-RCC underscore the potential for RET as a therapeutic target for treatment of patients with TFE3-RCC, and suggest that GPNMB may serve as diagnostic biomarker for TFE3 fusion RCC.

Cytomorphologic differentiation of benign and malignant mammary tumors in fine needle aspirate specimens from irradiated female Sprague-Dawley rats.

BACKGROUND: Fine needle aspiration (FNA) offers a rapid and minimally invasive means to distinguish malignant from benign neoplasms. However, few studies have been published regarding the cytopathology of mammary tumors in rats despite widespread use of the rat model for breast cancer formation and inhibition. OBJECTIVE: The purpose of this study was to determine the diagnostic accuracy of FNA cytology and to develop distinguishing cytologic criteria for the diagnosis of radiation-induced benign and malignant mammary tumors in rats. METHODS: In a study of radiation-induced mammary carcinogenesis, 100 Sprague-Dawley rats with cutaneous masses were randomly chosen for FNA. The aspirates were smeared, fixed, and stained with a modified Papanicolaou procedure for diagnostic evaluation. Cytologic and histologic diagnoses (benign vs malignant) were compared, and diagnostic accuracy was calculated using the histologic diagnosis as the criterion standard. FNA smears were scored semiquantitatively on a scale of 1-4 for cellularity, atypia, nuclear size, chromatin pattern, nuclear membrane thickness, nucleoli, and mitoses. The background was evaluated for necrosis, hemorrhage, inflammation, and mucosecretory material. Cytomorphologic features were compared statistically between benign and malignant tumors, based on the histologic diagnosis. RESULTS: The sensitivity of FNA was 92.3% and specificity was 89.4% for the detection of malignancy. However, 14% of specimens, all fibroadenomas by histology, had insufficient cells for cytologic evaluation, for an overall accuracy rate of 78.0%. Malignant tumors had significantly higher scores for all cytomorphologic features, and were significantly more likely to contain cell clusters and necrotic debris. CONCLUSIONS: FNA is an accurate method for differentiating benign and malignant rat mammary tumors.

Short telomeres and ataxia-telangiectasia mutated deficiency cooperatively increase telomere dysfunction and suppress tumorigenesis.

To examine the role of ataxia-telangiectasia mutated (Atm) in telomere function, we generated Atm and telomerase null mice (Atm(-/-) mTR(-/-) iG6 mice). These mice exhibited increased germ cell death and chromosome fusions compared with either Atm(-/-) or mTR(-/-) iG6 mice. Furthermore, the Atm(-/-) mTR(--) iG6 mice had a delayed onset and reduced incidence of thymic lymphoma compared with Atm(-/-) mice. The tumors in the Atm(-/-) mTR(-/-) iG6 mice showed increased apoptosis and anaphase bridges. Finally, lymphomas from Atm(-/-) mTR(-/-) iG6 mice were derived from CD8 immature, single-positive T cells, whereas Atm(-/-) lymphomas were from CD4(+)CD8(+) double-positive T cells. We propose that Atm protects short telomeres and that Atm deficiency cooperates with short telomeres, leading to increased cell death, decreased tumorigenesis, and increased overall survival.

Lack of correlation of vaginal impedance measurements with hormone levels in the rat.

Hormone levels vary in female rats depending on estrous cycle stage. Vaginal cytology is a reliable method of staging female rats, but vaginal impedance offers an alternative depending on application. We sought to correlate vaginal impedance in cycling female rats with hormone levels. Vaginal cytology was the standard for comparison and verification of estrous cycle stage. Female rats (n = 41) were evaluated twice daily for 15 days via vaginal cytology and impedance to evaluate two or three estrous cycles per rat. During the last 5 days of the study, selected anesthetized sampling groups (n = 3 or 4 rats per group) were bled terminally at each time point to allow hormone determinations concurrently with vaginal cytology and impedance. Rats with abnormal vaginal smears or discharges (n = 5) were evaluated for reproductive tract histology. Rats classified in estrus by vaginal cytology had significantly higher vaginal impedance values than did nonestrus rats, but vaginal impedance and estrous cycle stage as determined by vaginal cytology did not correlate. Because of small sampling size in nonproestrus groups, correlation between vaginal impedance and hormone levels was evaluated only in proestrus rats (n = 22) and was nonsignificant. No correlation occurred between vaginal impedance and hormone levels in unstaged rats (n = 41). Two animals evaluated for reproductive tract histology showed evidence of pseudopregnancy. Vaginal impedance may be useful in distinguishing estrus from nonestrus rats but may be limited for chronic estrous cycle monitoring because of the possible risk of inducing pseudopregnancy.

Estrous cycle and ovarian changes in a rat mammary carcinogenesis model after irradiation, tamoxifen chemoprevention, and aging.

PURPOSE: Variation in the effects of selective estrogen receptor modulators (SERMs) on the estrous cycle and reproductive organs during aging could play an important role in the observed heterogeneity of tamoxifen chemoprevention efficacy against breast cancer. METHODS: Of the 1,022 female Sprague Dawley rats enrolled in a long-term tamoxifen chemoprevention study, 87 were randomly chosen from four groups (irradiated, irradiated and tamoxifen treated, tamoxifen treated, and control). Vaginal smears were evaluated for determination of cycle stage, and vaginal pathologic changes. Correlation with the histologic features of reproductive tissues in 43 animals was made. RESULTS: More tamoxifen-treated (21.9%; 7/32) rats had irregular cycling than did control (9%; 3/23) rats. Ovarian granulosa cell hyperplasia was present in 50% (3/6) of tamoxifen-treated rats, and 20% (2/10) of control rats. Endometrial-type cells (ETCs) were present only in tamoxifen-treated (tamoxifen alone 6.25% [2/32]) and tamoxifen/ radiation-treated (28.6% [4/14]) rats. CONCLUSION: The modified Papanicolaou stain used here provided excellent morphologic detail for evaluating the estrous cycle in rodents. Tamoxifen altered vaginal cytologic and ovarian histologic features during aging. Results indicated that tamoxifen had direct and indirect effects on the reproductive tract, causing disturbance of the estrous cycle, shedding of ETCs, and promoting granulosa cell hyperplasia. Understanding of the heterogeneous response to tamoxifen chemoprevention during aging in rodents may provide important insights into the basis for tamoxifen chemoprevention failures in humans.

Endometrial-type cells in cervico-vaginal smears: clinical significance and cytopathologic correlates.

This study assessed the significance of endometrial-type cells (ETC) in cervico-vaginal (CV) smears in patients 45 yr and older by evaluating quantitatively and qualitatively the relationship of ETC to subsequent endometrial pathology. In a 3-yr period (1997-1999) at the Johns Hopkins Cytopathology Laboratory, 1,162 CV smears with ETC were found in patients 45 yr and older. In all cases with positive follow-up by tissue biopsy/resection, i.e., endometrial hyperplasia (EHP) and endometrial adenocarcinoma (EACA), the CV smears were reevaluated and compared to the control group (i.e., patients with normal endometrial biopsies). The following cytologic characteristics were recorded: quantity of ETC, type of ETC (epithelial, stromal/histiocyte-type, or mixed), cellular atypism, presence of inflammation, smear background, and associated estrogen effect. Of the 1,162 patients with ETC, 432 cases (37%) had tissue follow-up as follows: EACA, 18 (4.2%); EHP, 20 (4.6%); leiomyomata, 17 (3.9%); endometrial polyp, 21 (4.9%); benign/within normal limits (WNL), 339 (78.5%); nondiagnostic, 17 (3.9%). Cytologic characteristics of ETC showed subtle but definite quantitative and qualitative differences in the major pathologic groups examined. All instances of cancers and hyperplasia occurred in postmenopausal (PM) women. Abnormal vaginal bleeding was the presenting complaint in 66.7% of EACA, 45% of EHP, and 28.6% of benign endometrium. ETC in PM CV smears are associated with significant endometrial lesions (carcinoma, hyperplasia) in less than 9% of the patients. It is concluded that the distinction between EACA and EHP can be difficult. The presence of a large number of ETC, predominantly of epithelial or a mixed (epithelial and stromal) type, is more often associated with EACA or EHP than with benign endometrium. The presence of cytologic atypia and/or diathesis is additionally helpful for the diagnosis of EACA.

Hepatic calodium hepaticum (Nematoda) infection in a zoo colony of black-tailed prairie dogs (Cynomys ludovicianus).

Calodium hepaticum (syn. Capillaria hepatica), a nematode parasite commonly found in the liver of wild rodents, infects a wide variety of mammals, including humans. A retrospective study of black-tailed prairie dogs (Cynomys ludovicianus) at the Baltimore Zoo showed that 5 of 21 (24%) of the prairie dogs submitted for postmortem examination between 1981 and 2001 had hepatic capillariasis, with all the infections diagnosed during or after 1997. Affected livers contained multifocal granulomas containing numerous eggs and occasional adult nematodes. Asymptomatic wild rats in the zoo with a high prevalence of infection may have served as a reservoir for the disease. Wild rodent control is essential to minimize exposure of susceptible exhibition animals as well as humans to C. hepaticum.

Prom1 function in development, intestinal inflammation, and intestinal tumorigenesis.

Prom1/CD133 has been identified in colorectal, hepatocellular, and pancreatic cancer as a cancer stem cell marker and has been used as such to predict colon cancer recurrence in humans. Its potential molecular function as well as its role as a marker of intestinal regeneration is still not fully known. We evaluated the role of Prom1 in intestinal regeneration in inflammatory bowel disease (IBD), determined the function of Prom1, and characterized the effect of a lack of Prom1 on intestinal tumor formation in animal models. Our results suggest that Apc mutations lead to an increase in Prom1 expressing cells in the intestinal crypt stem cell compartment and in early intestinal adenomas. Also, Prom1 knockout mice are more susceptible to intestinal tumor formation. We conclude that Prom1 likely plays a role in regulating intestinal homeostasis and that these results clearly illustrate the role of Prom1 in intestinal regeneration. We further conclude that Prom1 may provide a novel therapeutic target for patients with gastrointestinal conditions such as IBD, short bowel syndrome, and colorectal cancer.

Mouse models for colorectal cancer.

Colorectal cancer (CRC) is the third leading cause of cancer-related death in the United States, with the number of affected people increasing. There are many risk factors that increase CRC risk, including family or personal history of CRC, smoking, consumption of red meat, obesity, and alcohol consumption. Conversely, increased screening, maintaining healthy body weight, not smoking, and limiting intake of red meat are all associated with reduced CRC morbidity and mortality. Mouse models of CRC were first used in 1928 and have played an important role in understanding CRC biology and treatment and have long been instrumental in clarifying the pathobiology of CRC formation and inhibition. This review focuses on advancements in modeling CRC in mice.

Abnormalities in cartilage and bone development in the Apert syndrome FGFR2(+/S252W) mouse.

Apert syndrome is an autosomal dominant disorder characterized by malformations of the skull, limbs and viscera. Two-thirds of affected individuals have a S252W mutation in fibroblast growth factor receptor 2 (FGFR2). To study the pathogenesis of this condition, we generated a knock-in mouse model with this mutation. The Fgfr2(+/S252W) mutant mice have abnormalities of the skeleton, as well as of other organs including the brain, thymus, lungs, heart and intestines. In the mutant neurocranium, we found a midline sutural defect and craniosynostosis with abnormal osteoblastic proliferation and differentiation. We noted ectopic cartilage at the midline sagittal suture, and cartilage abnormalities in the basicranium, nasal turbinates and trachea. In addition, from the mutant long bones, in vitro cell cultures grown in osteogenic medium revealed chondrocytes, which were absent in the controls. Our results suggest that altered cartilage and bone development play a significant role in the pathogenesis of the Apert syndrome phenotype.