Sphingolipid biosynthesis is essential for metabolic rewiring during TH17 cell differentiation

T helper 17 (TH17) cells are implicated in autoimmune diseases, and several metabolic processes are shown to be important for their development and function. In this study, we report an essential role for sphingolipids synthesized through the de novo pathway in TH17 cell development. Deficiency of SPTLC1, a major subunit of serine palmitoyl transferase enzyme complex that catalyzes the first and rate-limiting step of de novo sphingolipid synthesis, impaired glycolysis in differentiating TH17 cells by increasing intracellular reactive oxygen species (ROS) through enhancement of nicotinamide adenine dinucleotide phosphate oxidase 2 activity. Increased ROS leads to impaired activation of mammalian target of rapamycin C1 and reduced expression of hypoxia-inducible factor 1-alpha and c-Myc-induced glycolytic genes. SPTLCI deficiency protected mice from developing experimental autoimmune encephalomyelitis and experimental T cell transfer colitis. Our results thus show a critical role for de novo sphingolipid biosynthetic pathway in shaping adaptive immune responses with implications in autoimmune diseases.

Ibrutinib disrupts blood-tumor barrier integrity and prolongs survival in rodent glioma model

In malignant glioma, cytotoxic drugs are often inhibited from accessing the tumor site due to the blood-tumor barrier (BTB). Ibrutinib, FDA-approved lymphoma agent, inhibits Bruton tyrosine kinase (BTK) and has previously been shown to independently impair aortic endothelial adhesion and increase rodent glioma model survival in combination with cytotoxic therapy. Yet additional research is required to understand ibrutinib's effect on BTB function. In this study, we detail baseline BTK expression in glioma cells and its surrounding vasculature, then measure endothelial junctional expression/function changes with varied ibrutinib doses in vitro. Rat glioma cells and rodent glioma models were treated with ibrutinib alone (1-10 µM and 25 mg/kg) and in combination with doxil (10-100 µM and 3 mg/kg) to assess additive effects on viability, drug concentrations, tumor volume, endothelial junctional expression and survival. We found that ibrutinib, in a dose-dependent manner, decreased brain endothelial cell-cell adhesion over 24 h, without affecting endothelial cell viability (p < 0.005). Expression of tight junction gene and protein expression was decreased maximally 4 h after administration, along with inhibition of efflux transporter, ABCB1, activity. We demonstrated an additive effect of ibrutinib with doxil on rat glioma cells, as seen by a significant reduction in cell viability (p < 0.001) and increased CNS doxil concentration in the brain (56 ng/mL doxil alone vs. 74.6 ng/mL combination, p < 0.05). Finally, Ibrutinib, combined with doxil, prolonged median survival in rodent glioma models (27 vs. 16 days, p < 0.0001) with brain imaging showing a - 53% versus - 75% volume change with doxil alone versus combination therapy (p < 0.05). These findings indicate ibrutinib's ability to increase brain endothelial permeability via junctional disruption and efflux inhibition, to increase BTB drug entry and prolong rodent glioma model survival. Our results motivate the need to identify other BTB modifiers, all with the intent of improving survival and reducing systemic toxicities.

Carrier-Free, Amorphous Verteporfin Nanodrug for Enhanced Photodynamic Cancer Therapy and Brain Drug Delivery

Glioblastoma (GBM) is hard to treat due to cellular invasion into functioning brain tissues, limited drug delivery, and evolved treatment resistance. Recurrence is nearly universal even after surgery, chemotherapy, and radiation. Photodynamic therapy (PDT) involves photosensitizer administration followed by light activation to generate reactive oxygen species at tumor sites, thereby killing cells or inducing biological changes. PDT can ablate unresectable GBM and sensitize tumors to chemotherapy. Verteporfin (VP) is a promising photosensitizer that relies on liposomal carriers for clinical use. While lipids increase VP's solubility, they also reduce intracellular photosensitizer accumulation. Here, a pure-drug nanoformulation of VP, termed "NanoVP", eliminating the need for lipids, excipients, or stabilizers is reported. NanoVP has a tunable size (65-150 nm) and 1500-fold higher photosensitizer loading capacity than liposomal VP. NanoVP shows a 2-fold increase in photosensitizer uptake and superior PDT efficacy in GBM cells compared to liposomal VP. In mouse models, NanoVP-PDT improved tumor control and extended animal survival, outperforming liposomal VP and 5-aminolevulinic acid (5-ALA). Moreover, low-dose NanoVP-PDT can safely open the blood-brain barrier, increasing drug accumulation in rat brains by 5.5-fold compared to 5-ALA. NanoVP is a new photosensitizer formulation that has the potential to facilitate PDT for the treatment of GBM.

Role of colchicine to reduce NLRP3 marker in STEMI patients undergo primary PCI: A randomised controlled clinical trial

INTRODUCTION

ST-segment elevation myocardial infarction (STEMI) is a fatal disease with significant burden worldwide. Despite advanced medical treatment performed, STEMIrelated morbidity and mortality remains high due to ischemia reperfusion injury after primary angioplasty mediated by NLRP3 inflammasome. Adding colchicine expected to reduce inflammation both in vitro and in vivo. We want to evaluate the effect of colchicine administration on the NLRP3 level of STEMI patient who undergo primary cutaneous intervention (PCI).

MATERIALS AND METHODS

Randomised controlled trial was conducted on STEMI patients who undergo PCI in two hospitals in Jakarta, 104 patients enrolled to this study, and 77 patients completed the trial. 37 patients were randomly assigned to receive colchicines (2 mg loading dose; 0.5 mg thereafter every 12 hour for 48 hours) while 40 patients received placebo. NLRP3 level was measured from venous blood at baseline (BL), after procedure (AP), dan 24-hour post procedure (24H).

RESULTS

No NLRP3 difference was observed initially between colchicine arm and placebo arm 38,69 and 39,0138, respectively (p >0.05). Measurement conducted at 24H, patients received colchicine demonstrate reduction in NLRP3 level (37.67), while placebo arm results increase in NLRP3 level (42.89) despite not statistically significant (p >0,05).

CONCLUSION

Colchicine addition to standard treatment of STEMI patients undergo PCI reduce NLRP3 level despite statistically insignificant.

Characterization of BRCA2 R3052Q variant in mice supports its functional impact as a low-risk variant

Pathogenic variants in BRCA2 are known to significantly increase the lifetime risk of developing breast and ovarian cancers. Sequencing-based genetic testing has resulted in the identification of thousands of BRCA2 variants that are considered to be variants of uncertain significance (VUS) because the disease risk associated with them is unknown. One such variant is p.Arg3052Gln, which has conflicting interpretations of pathogenicity in the ClinVar variant database. Arginine at position 3052 in BRCA2 plays an important role in stabilizing its C-terminal DNA binding domain. We have generated a knock-in mouse model expressing this variant to examine its role on growth and survival in vivo. Homozygous as well as hemizygous mutant mice are viable, fertile and exhibit no overt phenotype. While we did not observe any hematopoietic defects in adults, we did observe a marked reduction in the in vitro proliferative ability of fetal liver cells that were also hypersensitive to PARP inhibitor, olaparib. In vitro studies performed on embryonic and adult fibroblasts derived from the mutant mice showed significant reduction in radiation induced RAD51 foci formation as well as increased genomic instability after mitomycin C treatment. We observed mis-localization of a fraction of R3052Q BRCA2 protein to the cytoplasm which may explain the observed in vitro phenotypes. Our findings suggest that BRCA2 R3052Q should be considered as a hypomorphic variant.

Immune Effects of Cryoablation in Woodchuck Hepatocellular Carcinoma

Objectives

Local and systemic immune responses evoked by locoregional therapies such as cryoablation are incompletely understood. The aim of this study was to characterize cryoablation-related immune response and the capacity of immune drugs to augment immunity upon cryoablation for the treatment of hepatocellular carcinoma (HCC) using a woodchuck hepatocellular carcinoma model.

Materials and Methods

Twelve woodchucks chronically infected with woodchuck hepatitis virus and with hepatocellular carcinoma underwent imaging with contrast-enhanced CT. Partial cryoablation of tumors in three woodchucks was performed. Fourteen days after cryoablation, liver tissues were harvested and stained with H&E and TUNEL, and immune infiltrates were quantified. Peripheral blood mononuclear cells (PBMC) were collected from ablated and nonablated woodchucks, labeled with carboxyfluorescein succinimidyl ester (CFSE) and cultured with immune-modulating drugs, including a small PD-L1 antagonist molecule (BMS-202) and three TLR7/8 agonists (DSR 6434, GS-9620, gardiquimod). After incubation, cell replication and immune cell populations were analyzed by flow cytometry.

Results

Local immune response in tumors was characterized by an increased number of CD3+ T lymphocytes and natural killer cells in the cryolesion margin compared to other tumor regions. T regulatory cells were found in higher numbers in distant tumors within the liver compared to untreated or control tumors. Cryoablation also augmented the systemic immune response as demonstrated by higher numbers of PBMC responses upon immune drug stimulation in the cryoablation group.

Conclusions

Partial cryoablation augmented immune effects in both treated and remote untreated tumor microenvironments, as well as systemically, in woodchucks with HCC. Characterization of these mechanisms may enhance development of novel drug-device combinations for treatment of HCC.

Targeting Replication Stress and Chemotherapy Resistance with a Combination of Sacituzumab Govitecan and Berzosertib: A Phase I Clinical Trial

PURPOSE

Despite promising preclinical studies, toxicities have precluded combinations of chemotherapy and DNA damage response (DDR) inhibitors. We hypothesized that tumor-targeted chemotherapy delivery might enable clinical translation of such combinations.

PATIENTS AND METHODS

In a phase I trial, we combined sacituzumab govitecan, antibody-drug conjugate (ADC) that delivers topoisomerase-1 inhibitor SN-38 to tumors expressing Trop-2, with ataxia telangiectasia and Rad3-related (ATR) inhibitor berzosertib. Twelve patients were enrolled across three dose levels.

RESULTS

Treatment was well tolerated, with improved safety over conventional chemotherapy-based combinations, allowing escalation to the highest dose. No dose-limiting toxicities or clinically relevant ≥grade 4 adverse events occurred. Tumor regressions were observed in 2 patients with neuroendocrine prostate cancer, and a patient with small cell lung cancer transformed from EGFR-mutant non-small cell lung cancer.

CONCLUSIONS

ADC-based delivery of cytotoxic payloads represents a new paradigm to increase efficacy of DDR inhibitors. See related commentary by Berg and Choudhury, p. 3557.

Organoids and metastatic orthotopic mouse model for mismatch repair-deficient colorectal cancer

Background

Genome integrity is essential for the survival of an organism. DNA mismatch repair (MMR) genes (e.g., MLH1, MSH2, MSH6, and PMS2) play a critical role in the DNA damage response pathway for genome integrity maintenance. Germline mutations of MMR genes can lead to Lynch syndrome or constitutional mismatch repair deficiency syndrome, resulting in an increased lifetime risk of developing cancer characterized by high microsatellite instability (MSI-H) and high mutation burden. Although immunotherapy has been approved for MMR-deficient (MMRd) cancer patients, the overall response rate needs to be improved and other management options are needed.

Methods

To better understand the biology of MMRd cancers, elucidate the resistance mechanisms to immune modulation, and develop vaccines and therapeutic testing platforms for this high-risk population, we generated organoids and an orthotopic mouse model from intestine tumors developed in a Msh2-deficient mouse model, and followed with a detailed characterization.

Results

The organoids were shown to be of epithelial origin with stem cell features, to have a high frameshift mutation frequency with MSI-H and chromosome instability, and intra- and inter-tumor heterogeneity. An orthotopic model using intra-cecal implantation of tumor fragments derived from organoids showed progressive tumor growth, resulting in the development of adenocarcinomas mixed with mucinous features and distant metastasis in liver and lymph node.

Conclusions

The established organoids with characteristics of MSI-H cancers can be used to study MMRd cancer biology. The orthotopic model, with its distant metastasis and expressing frameshift peptides, is suitable for evaluating the efficacy of neoantigen-based vaccines or anticancer drugs in combination with other therapies.

PRDM10 RCC: A Birt-Hogg-Dubé-like Syndrome Associated With Lipoma and Highly Penetrant, Aggressive Renal Tumors Morphologically Resembling Type 2 Papillary Renal Cell Carcinoma

OBJECTIVE

To characterize the clinical manifestations and genetic basis of a familial cancer syndrome in patients with lipomas and Birt-Hogg-Dubé-like clinical manifestations including fibrofolliculomas and trichodiscomas and kidney cancer.

METHODS

Genomic analysis of blood and renal tumor DNA was performed. Inheritance pattern, phenotypic manifestations, and clinical and surgical management were documented. Cutaneous, subcutaneous, and renal tumor pathologic features were characterized.

RESULTS

Affected individuals were found to be at risk for a highly penetrant and lethal form of bilateral, multifocal papillary renal cell carcinoma. Whole genome sequencing identified a germline pathogenic variant in PRDM10 (c.2029 T>C, p.Cys677Arg), which cosegregated with disease. PRDM10 loss of heterozygosity was identified in kidney tumors. PRDM10 was predicted to abrogate expression of FLCN, a transcriptional target of PRDM10, which was confirmed by tumor expression of GPNMB, a TFE3/TFEB target and downstream biomarker of FLCN loss. In addition, a sporadic papillary RCC from the TCGA cohort was identified with a somatic PRDM10 mutation.

CONCLUSION

We identified a germline PRDM10 pathogenic variant in association with a highly penetrant, aggressive form of familial papillary RCC, lipomas, and fibrofolliculomas/trichodiscomas. PRDM10 loss of heterozygosity and elevated GPNMB expression in renal tumors indicate that PRDM10 alteration leads to reduced FLCN expression, driving TFE3-induced tumor formation. These findings suggest that individuals with Birt-Hogg-Dubé-like manifestations and subcutaneous lipomas, but without a germline pathogenic FLCN variant, should be screened for germline PRDM10 variants. Importantly, kidney tumors identified in patients with a pathogenic PRDM10 variant should be managed with surgical resection instead of active surveillance.

Abstract 6518: Time course genomic characterization reveals progressive accumulation of mutations during tumor development in a Lynch syndrome mouse model

DNA mismatch repair (MMR) genes (e.g., MLH1, MSH2, MSH6, PMS2, and EPCAM) play an important role in maintaining genomic stability during DNA replication and recombination. Deficiency in MMR resulting from mutations in these genes leads to mutations in microsatellite regions throughout the genome (microsatellite instability; MSI) and in cancer driver oncogenes or tumor suppressor genes, which accumulate over time and eventually lead to cancer formation. Monoallelic germline mutation in MMR genes causes Lynch syndrome (LS). Among LS-related cancer types, the lifetime risk for colorectal cancer (CRC) is the highest (~80%). Frameshift mutations (FSMs) in coding microsatellites produce neoantigens, which have been shown to elicit immune responses. It was thus postulated that they can serve as vaccine targets. To develop a prophylactic vaccine and prevention strategy for this high-risk population, we characterized a LS mouse model (Msh2LoxP/LoxP;Villin-Cre) to determine whether these mice recapitulate the human LS oncogenic process. We found that tumor development was already notable at 7-8 months of age and median survival was 11.5 months. Histopathological analysis showed that tumors were adenoma or adenocarcinoma mixed with mucinous features. Using a targeted sequencing approach, a panel of FSMs in mononucleotide regions were identified in both tumors and histologically normal mucosa, suggesting that Msh2 deletion and FSMs were not sufficient for tumor development. In addition, Apc, Ctnnb, and Trp53 mutations were also observed with low frequency in organoids derived from these tumors, indicating that other driver mutations may be required for tumor initiation and progression, and most FSMs detected in tumors and mucosa were probably passenger mutations. To determine if fecal samples can be used to monitor the FSM load, fecal DNA from different time points was sequenced. We found that FSMs can be detected at 1month of age although the number of FSMs was relatively low compared to that from older mice, indicating that FSMs accumulate over time. MSI detection via fragment analysis confirmed that these tumors were MSI-H. Interestingly, mucosa and fecal samples from a time course study showed progressive increase in microsatellite instability, suggesting the possibility of using MSI score for disease monitoring. Our preliminary data indicates that combined fecal FSM status and MSI score can be potentially used as a biomarker to monitor the tumor development and disease progression for LS colorectal cancer.

Funded by the National Cancer Institute, National Institutes of Health, under Contract No. HHSN261201500003I

Citation Format: Yurong Song, Shaneen Baxter, Lisheng Dai, Chelsea Sanders, Holli Loomans-Kropp, Brandon Somerville, Ryan N. Baugher, Stephanie D. Mellott, Todd B. Young, Heidi E. Lawhorn, Teri M. Plona, Bingfang Xu, Lei Wei, Qiang Hu, Song Liu, Alan Hutson, Baktiar Karim, Simone Difilippantonio, Ligia Pinto, Matthias Kloor, Steven M. Lipkin, Shizuko Sei, Robert H. Shoemaker. Time course genomic characterization reveals progressive accumulation of mutations during tumor development in a Lynch syndrome mouse model. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6518.

Abstract 2320: Dissecting the effects of Smyd3 depletion in the tumor microenvironment of HPV-negative head and neck squamous cell carcinoma mouse models

Human papilloma virus (HPV)-negative head and neck squamous cell carcinoma (HNSCC) patients have a poor prognosis and most patients with metastatic disease are resistant to pembrolizumab. We recently showed that depletion of SET and MYND domain protein 3 (SMYD3), a protein methyltransferase, induces upregulation of multiple type I IFN response genes in HPV-negative HNSCC human and mouse cells in vitro. Systemic treatment of flank HPV-negative mouse oral carcinoma 1 (MOC1) tumors with Smyd3 anti-sense oligonucleotides (ASOs) induced influx of CD8+ T-cells, and combined Smyd3 ASOs and anti-PD-1 treatment induced tumor growth restraint, with 75% of tumors cured or reduced and 25% of tumors escaping. Here, we aim to investigate the changes in the tumor microenvironment (TME) of MOC1 tumors treated with Smyd3 ASOs and in combination with anti-PD-1, and to elucidate mechanisms of resistance. MOC1 tumors treated with control or Smyd3 ASOs (n=3 per group) were harvested and single-cell RNA-seq was conducted. GeoMx, a high-plex spatial proteomic assay, was utilized on FFPE sections of MOC1 tumors treated with control or Smyd3 ASOs with or without anti-PD-1 (n=2 per group). To decipher mechanisms of resistance, single-cell RNA-seq of MOC1 tumors that responded or not to combination Smyd3 ASOs and anti-PD-1 was conducted. 26926 cells from six samples were available for single-cell RNA-seq analysis of control versus Smyd3 ASO treated tumors. UMAP analysis identified distinct immune-, stroma- and cancer-cell populations. Comparative analysis of the single-cell Smyd3 mRNA expression revealed downregulation of Smyd3 mRNA in CD8+ and CD4+ T-cells, B-cells, NK-cells and cancer cells, but not in myeloid cells, endothelial cells and fibroblasts, implying differential uptake of Smyd3 ASOs in the TME. CD8+ T-cells in the Smyd3 ASO treated tumors exhibited higher expression levels of Gzma and Gzmb, indicating enhanced cytotoxic activity. Colony stimulating factor 1 (Csf1), which is important for the differentiation of macrophages, was upregulated in CD8+ T-cells of Smyd3 ASO treated tumors. Single-cell RNA-seq of a non-responder versus a responder MOC1 tumor yielded 9170 and 11410 cells respectively, with more than a two-fold increase in the ratio of neutrophils and a two-fold decrease for CD8+ T-cells comparing the non-responder to responder tumor. Accordingly, cancer cells, CD8+ T-cells and macrophages of the non-responder tumor exhibited higher expression of Cxcl2, a chemokine that attracts PMNs. Differential gene expression analysis in all cell subsets in control versus Smyd3 ASO and responder versus non-responder tumors is ongoing. This work will elucidate the TME changes induced by Smyd3 ASOs in MOC1 tumors, and will reveal potential mechanisms of resistance to the Smyd3 ASOs and anti-PD-1 combination, enabling translation of this therapeutic approach in HPV-negative HNSCC.

Citation Format: Malhar Patel, Daniel Tsai, Abdalla Abdelmaksoud, Noemi Kedei, Maria Hernandez, Baktiar Karim, Vassiliki Saloura. Dissecting the effects of Smyd3 depletion in the tumor microenvironment of HPV-negative head and neck squamous cell carcinoma mouse models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2320.

Whole Organism Profiling of the Timp Gene Family

Tissue inhibitor of metalloproteinases (TIMPs/Timps) are an endogenous family of widely expressed matrisome-associated proteins that were initially identified as inhibitors of matrix metalloproteinase activity (Metzincin family proteases). Consequently, TIMPs are often considered simply as protease inhibitors by many investigators. However, an evolving list of new metalloproteinase-independent functions for TIMP family members suggests that this concept is outdated. These novel TIMP functions include direct agonism/antagonism of multiple transmembrane receptors, as well as functional interactions with matrisome targets. While the family was fully identified over two decades ago, there has yet to be an in-depth study describing the expression of TIMPs in normal tissues of adult mammals. An understanding of the tissues and cell-types that express TIMPs 1 through 4, in both normal and disease states are important to contextualize the growing functional capabilities of TIMP proteins, which are often dismissed as non-canonical. Using publicly available single cell RNA sequencing data from the Tabula Muris Consortium, we analyzed approximately 100,000 murine cells across eighteen tissues from non-diseased organs, representing seventy-three annotated cell types, to define the diversity in Timp gene expression across healthy tissues. We describe the unique expression profiles across tissues and organ-specific cell types that all four Timp genes display. Within annotated cell-types, we identify clear and discrete cluster-specific patterns of Timp expression, particularly in cells of stromal and endothelial origins. RNA in-situ hybridization across four organs expands on the scRNA sequencing analysis, revealing novel compartments associated with individual Timp expression. These analyses emphasize a need for specific studies investigating the functional significance of Timp expression in the identified tissues and cell sub-types. This understanding of the tissues, specific cell types and microenvironment conditions in which Timp genes are expressed adds important physiological context to the growing array of novel functions for TIMP proteins.

TFEB and TFE3 drive kidney cystogenesis and tumorigenesis

Birt-Hogg-Dubé (BHD) syndrome is an inherited familial cancer syndrome characterized by the development of cutaneous lesions, pulmonary cysts, renal tumors and cysts and caused by loss-of-function pathogenic variants in the gene encoding the tumor-suppressor protein folliculin (FLCN). FLCN acts as a negative regulator of TFEB and TFE3 transcription factors, master controllers of lysosomal biogenesis and autophagy, by enabling their phosphorylation by the mechanistic Target Of Rapamycin Complex 1 (mTORC1). We have previously shown that deletion of Tfeb rescued the renal cystic phenotype of kidney-specific Flcn KO mice. Using Flcn/Tfeb/Tfe3 double and triple KO mice, we now show that both Tfeb and Tfe3 contribute, in a differential and cooperative manner, to kidney cystogenesis. Remarkably, the analysis of BHD patient-derived tumor samples revealed increased activation of TFEB/TFE3-mediated transcriptional program and silencing either of the two genes rescued tumorigenesis in human BHD renal tumor cell line-derived xenografts (CDXs). Our findings demonstrate in disease-relevant models that both TFEB and TFE3 are key drivers of renal tumorigenesis and suggest novel therapeutic strategies based on the inhibition of these transcription factors.

Loss of Brca1 and Trp53 in adult mouse mammary ductal epithelium results in development of hormone receptor-positive or hormone receptor-negative tumors, depending on inactivation of Rb family proteins

Background

Breast cancer is a heterogenous disease with several histological and molecular subtypes. Models that represent these subtypes are essential for translational research aimed at improving clinical strategy for targeted therapeutics.

Methods

Different combinations of genetic aberrations (Brca1 and Trp53 loss, and inhibition of proteins of the Rb family) were induced in the mammary gland by injection of adenovirus expressing Cre recombinase into the mammary ducts of adult genetically engineered mice. Mammary tumors with different genetic aberrations were classified into molecular subtypes based on expression of molecular markers and RNAseq analysis. In vitro potency assays and Western blots were used to examine their drug sensitivities.

Results

Induction of Brca1 and Trp53 loss in mammary ductal epithelium resulted in development of basal-like hormone receptor (HR)-negative mammary tumors. Inhibition of Rb and Trp53 loss or the combination of Rb, Trp53 and Brca1 aberrations resulted in development of luminal ductal carcinoma positive for ER, PR, and Her2 expression. HR positivity in tumors with Rb, Trp53 and Brca1 aberrations indicated that functionality of the Rb pathway rather than Brca1 status affected HR status in these models. Mammary tumor gene expression profiles recapitulated human basal-like or luminal B breast cancer signatures, but HR-positive luminal cancer models were endocrine resistant and exhibited upregulation of PI3K signaling and sensitivity to this pathway inhibition. Furthermore, both tumor subtypes were resistant to CDK4/6 inhibition.

Conclusions

Examination of molecular expression profiles and drug sensitivities of tumors indicate that these breast cancer models can be utilized as a translational platform for evaluation of targeted combinations to improve chemotherapeutic response in patients that no longer respond to hormone therapy or that are resistant to CDK4/6 inhibition.

Mesothelioma Mouse Models with Mixed Genomic States of Chromosome and Microsatellite Instability

Simple Summary

Only a limited number of murine mesothelioma cell lines have been developed to date. We sought to expand this number and to characterize the models in detail to enable studying mesothelioma biology in vivo. Two cell lines were identified as showing well-defined mesothelioma biomarkers and being suitable for preclinical use. In the course of our studies, we observed a mixed phenotype of chromosomal instability and microsatellite instability not previously reported in mouse models. Moreover, microsatellite markers were detectable in the plasma of tumor-bearing animals, which potentially can be used as non-invasive biomarkers for early cancer detection and monitoring the effects of interventions.

Abstract

Malignant mesothelioma (MMe) is a rare malignancy originating from the linings of the pleural, peritoneal and pericardial cavities. The best-defined risk factor is exposure to carcinogenic mineral fibers (e.g., asbestos). Genomic studies have revealed that the most frequent genetic lesions in human MMe are mutations in tumor suppressor genes. Several genetically engineered mouse models have been generated by introducing the same genetic lesions found in human MMe. However, most of these models require specialized breeding facilities and long-term exposure of mice to asbestos for MMe development. Thus, an alternative model with high tumor penetrance without asbestos is urgently needed. We characterized an orthotopic model using MMe cells derived from Cdkn2a^+/−;Nf2^+/− mice chronically injected with asbestos. These MMe cells were tumorigenic upon intraperitoneal injection. Moreover, MMe cells showed mixed chromosome and microsatellite instability, supporting the notion that genomic instability is relevant in MMe pathogenesis. In addition, microsatellite markers were detectable in the plasma of tumor-bearing mice, indicating a potential use for early cancer detection and monitoring the effects of interventions. This orthotopic model with rapid development of MMe without asbestos exposure represents genomic instability and specific molecular targets for therapeutic or preventive interventions to enable preclinical proof of concept for the intervention in an immunocompetent setting.

BRCA2-DSS1 interaction is dispensable for RAD51 recruitment at replication-induced and meiotic DNA double strand breaks

The interaction between tumor suppressor BRCA2 and DSS1 is essential for RAD51 recruitment and repair of DNA double stand breaks (DSBs) by homologous recombination (HR). We have generated mice with a leucine to proline substitution at position 2431 of BRCA2, which disrupts this interaction. Although a significant number of mutant mice die during embryogenesis, some homozygous and hemizygous mutant mice undergo normal postnatal development. Despite lack of radiation induced RAD51 foci formation and a severe HR defect in somatic cells, mutant mice are fertile and exhibit normal RAD51 recruitment during meiosis. We hypothesize that the presence of homologous chromosomes in close proximity during early prophase I may compensate for the defect in BRCA2-DSS1 interaction. We show the restoration of RAD51 foci in mutant cells when Topoisomerase I inhibitor-induced single strand breaks are converted into DSBs during DNA replication. We also partially rescue the HR defect by tethering the donor DNA to the site of DSBs using streptavidin-fused Cas9. Our findings demonstrate that the BRCA2-DSS1 complex is dispensable for RAD51 loading when the homologous DNA is close to the DSB.

Mishra et al. have generated mice with a single amino acid substitution in BRCA2, which disrupts its interaction with DSS1 resulting in a severe HR defect. They show the interaction to be dispensable for HR at replication induced and meiotic DSBs.

Alpha synuclein, the culprit in Parkinson disease, is required for normal immune function

Alpha-synuclein (αS) is causally involved in the development of Parkinson disease (PD); however, its role in normal vertebrate physiology has remained unknown. Recent studies demonstrate that αS is induced by noroviral infection in the enteric nervous system of children and protects mice against lethal neurotropic viral infection. Additionally, αS is a potent chemotactic activator of phagocytes. In this report, using both wild-type and αS knockout mice, we show that αS is a critical mediator of inflammatory and immune responses. αS is required for the development of a normal inflammatory response to bacterial peptidoglycan introduced into the peritoneal cavity as well as antigen-specific and T cell responses following intraperitoneal immunization. Furthermore, we show that neural cells are the sources of αS required for immune competence. Our report supports the hypothesis that αS accumulates within the nervous system of PD individuals because of an inflammatory/immune response.

Surface-fill hydrogel attenuates the oncogenic signature of complex anatomical surface cancer in a single application

Tumours growing in a sheet-like manner on the surface of organs and tissues with complex topologies represent a difficult-to-treat clinical scenario. Their complete surgical resection is difficult due to the complicated anatomy of the diseased tissue. Residual cancer often responds poorly to systemic therapy and locoregional treatment is hindered by the limited accessibility to microscopic tumour foci. Here we engineered a peptide-based surface-fill hydrogel (SFH) that can be syringe- or spray-delivered to surface cancers during surgery or used as a primary therapy. Once applied, SFH can shape change in response to alterations in tissue morphology that may occur during surgery. Implanted SFH releases nanoparticles composed of microRNA and intrinsically disordered peptides that enter cancer cells attenuating their oncogenic signature. With a single application, SFH shows efficacy in four preclinical models of mesothelioma, demonstrating the therapeutic impact of the local application of tumour-specific microRNA, which might change the treatment paradigm for mesothelioma and possibly other surface cancers.

Insertional activation of STAT3 and LCK by HIV-1 proviruses in T cell lymphomas

Retroviruses cause cancers in animals by integrating in or near oncogenes. Although HIV-1 infection increases the risk of cancer, most of the risk is associated with immunodeficiency and coinfection by oncogenic virus (Epstein-Barr virus, Kaposi sarcoma herpesvirus, and human papillomavirus). HIV-1 proviruses integrated in some oncogenes cause clonal expansion of infected T cells in vivo; however, the infected cells are not transformed, and it is generally believed that HIV-1 does not cause cancer directly. We show that HIV-1 proviruses integrated in the first introns of signal transducer and activator of transcription 3 (STAT3) and lymphocyte-specific protein tyrosine kinase (LCK) can play an important role in the development of T cell lymphomas. The development of these cancers appears to be a multistep process involving additional nonviral mutations, which could help explain why T cell lymphomas are rare in persons with HIV-1 infection.

Mastocytosis-derived extracellular vesicles deliver miR-23a and miR-30a into pre-osteoblasts and prevent osteoblastogenesis and bone formation

Osteoporosis and other manifestations of bone disease are frequent in patients with systemic mastocytosis (SM) in association with the presence of mast cell infiltrates in bone marrow, although the mechanisms behind bone disease remain poorly understood. We find that extracellular vesicles (EVs) released by neoplastic mast cells and present in the serum of patients with SM (SM-EVs) block osteoblast differentiation and mineralization in culture, and when injected into mice diminish the expression of osteoblast markers, and trabecular bone volume and microarchitecture. We demonstrate that miRNA-30a and miRNA-23a, increased in SM-EVs and neoplastic mast cell-derived EVs, attenuate osteoblast maturation by suppressing expression of RUNX2 and SMAD1/5, essential drivers of osteogenesis. Thus, SM-EVs carry and deliver miRNAs that epigenetically interfere with bone formation and can contribute to bone mass reduction in SM. These findings also suggest possibilities for novel approaches to the management of bone disease in mast cell proliferative disorders.

Osteoporosis and bone disease are common in patients with systemic mastocytosis. Here, the authors show that extracellular vesicles released by neoplastic mast cells of the patients block osteoblast differentiation and bone mineralization when injected into mice, via a mechanism involving suppression of osteogenic factors via miRNA-30a and miRNA-23a.

CENP-A overexpression promotes aneuploidy with karyotypic heterogeneity

Chromosomal instability (CIN) is a hallmark of many cancers. Restricting the localization of centromeric histone H3 variant CENP-A to centromeres prevents CIN. CENP-A overexpression (OE) and mislocalization have been observed in cancers and correlate with poor prognosis; however, the molecular consequences of CENP-A OE on CIN and aneuploidy have not been defined. Here, we show that CENP-A OE leads to its mislocalization and CIN with lagging chromosomes and micronuclei in pseudodiploid DLD1 cells and xenograft mouse model. CIN is due to reduced localization of proteins to the kinetochore, resulting in defects in kinetochore integrity and unstable kinetochore–microtubule attachments. CENP-A OE contributes to reduced expression of cell adhesion genes and higher invasion of DLD1 cells. We show that CENP-A OE contributes to aneuploidy with karyotypic heterogeneity in human cells and xenograft mouse model. In summary, our results provide a molecular link between CENP-A OE and aneuploidy, and suggest that karyotypic heterogeneity may contribute to the aggressive phenotype of CENP-A–overexpressing cancers.

Imaging, Pathology, and Immune Correlates in the Woodchuck Hepatic Tumor Model

Background

Woodchucks chronically infected with woodchuck hepatitis virus (WHV), which resembles human hepatitis B virus, develop spontaneous hepatic tumors and may be an important biological and immunological model for human HCC. Nonetheless, this model requires further validation to fully realize its translational potential.

Methods

Woodchucks infected at birth with WHV that had developed HCC (n=12) were studied. Computed tomography, ultrasound, and magnetic resonance imaging were performed under anesthesia. LI-RADS scoring and correlative histologic analysis of sectioned tissues were performed. For immune characterization of tumors, CD3 (T cells), CD4 (T helpers), NCAM (Natural killers), FOXP3 (T-regulatory), PDL-1 (inhibitory checkpoint protein), and the human hepatocellular carcinoma (HCC) biomarker alpha-fetoprotein (AFP) immunohistochemical stains were performed.

Results

Forty tumors were identified on imaging of which 29 were confirmed to be HCC with 26 categorized as LR-4 or 5. The remainder of the tumors had benign histology including basophilic foci, adenoma, and lipidosis as well as pre-malignant dysplastic foci. LR-4 and LR-5 lesions showed high sensitivity (90%) and specificity (100%) for malignant and pre-malignant tumors. Natural killers count was found to be 2–5 times lower in tumors relative to normal parenchyma while other immune cells were located in the periphery of tumors. Tumors expressed AFP and did not express PD-L1.

Conclusion

Woodchucks chronically infected with WHV developed diverse hepatic tumor types with diagnostic imaging, pathology, and immune patterns comparable to that in humans. This unique animal model may provide a valuable tool for translation and validation of novel image-guided and immune-therapeutic investigations.

Alpha-synuclein (αS) functions as an alarmin to promote inflammatory and immune responses by activating dendritic cells and macrophages

Alpha-synuclein (αS) is causally involved in the development of neurodegenerative disorders including Parkinson’s disease (PD). Recently, αS has been shown to be a chemotactic activator of phagocytes. Here, we report that αS is a critical mediator of inflammatory and immune responses. Treatment with αS activated human and mouse dendritic cells (DCs) and macrophages at both phenotypic and functional levels. αS treatment of DCs triggered the NF-κB signaling pathway and predominantly enhanced their Th1-polarizing capacity. αS also polarized mouse macrophages in an M1 direction. Activation of APCs by αS was mediated by TLR4. Intraperitoneal administration of αS recruited DCs and macrophages into the peritoneal cavity, while inflammatory reactions in the peritoneal cavity and colons induced αS expression and production. Importantly, immunization with ovalbumin (OVA) in the presence of αS promoted OVA-specific antibody and T cell responses, whereas the induction of inflammatory and OVA-specific immune responses was markedly reduced in αS−/− mice. Thus, αS can be considered an alarmin that functions as a mediator of inflammatory and immune responses. The potent proinflammatory and immunostimulating effects of αS in the periphery may cause the accumulation of αS and inflammatory damage in the central nervous system, culminating in Parkinson disease (PD).

Enterotoxigenic Bacteroides fragilis infection exacerbates tumorigenesis in AOM/DSS mouse model

The azoxymethane (AOM)/dextran sulfate sodium (DSS) murine model is commonly used to study colitis-associated cancer. The human commensal bacterium, enterotoxigenic Bacteroides fragilis (ETBF) secretes the Bacteroides fragilis toxin (BFT) which is necessary and sufficient to cause colitis. We report that BALB/c mice infected with WT-ETBF and administered three cycles of AOM/DSS developed numerous, large-sized polyps predominantly in the colorectal region. In addition, AOM/DSS-treated BALB/c mice orally inoculated with wild-type nontoxigenic Bacteroides fragilis (WT-NTBF) overexpressing bft (rETBF) developed numerous polyps whereas mice infected with WT-NTBF overexpressing a biologically inactive bft (rNTBF) did not promote polyp formation. Unexpectedly, the combination of AOM+ETBF did not induce polyp formation whereas ETBF+DSS did induce polyp development in a subset of BALB/c mice. In conclusion, WT-ETBF promoted polyp development in AOM/DSS murine model with increased colitis in BALB/c mice. The model described herein provides an experimental platform for understanding ETBF-induced colonic tumorigenesis and studying colorectal cancer in wild-type mice.

Cell division rates decrease with age, providing a potential explanation for the age-dependent deceleration in cancer incidence

A new evaluation of previously published data suggested to us that the accumulation of mutations might slow, rather than increase, as individuals age. To explain this unexpected finding, we hypothesized that normal stem cell division rates might decrease as we age. To test this hypothesis, we evaluated cell division rates in the epithelium of human colonic, duodenal, esophageal, and posterior ethmoid sinonasal tissues. In all 4 tissues, there was a significant decrease in cell division rates with age. In contrast, cell division rates did not decrease in the colon of aged mice, and only small decreases were observed in their small intestine or esophagus. These results have important implications for understanding the relationship between normal stem cells, aging, and cancer. Moreover, they provide a plausible explanation for the enigmatic age-dependent deceleration in cancer incidence in very old humans but not in mice.

BRCA1 Haploinsufficiency Is Masked by RNF168-Mediated Chromatin Ubiquitylation

BRCA1 functions at two distinct steps during homologous recombination (HR). Initially, it promotes DNA end resection, and subsequently it recruits the PALB2 and BRCA2 mediator complex, which stabilizes RAD51-DNA nucleoprotein filaments. Loss of 53BP1 rescues the HR defect in BRCA1-deficient cells by increasing resection, suggesting that BRCA1's downstream role in RAD51 loading is dispensable when 53BP1 is absent. Here we show that the E3 ubiquitin ligase RNF168, in addition to its canonical role in inhibiting end resection, acts in a redundant manner with BRCA1 to load PALB2 onto damaged DNA. Loss of RNF168 negates the synthetic rescue of BRCA1 deficiency by 53BP1 deletion, and it predisposes BRCA1 heterozygous mice to cancer. BRCA1^+/-RNF168^-/- cells lack RAD51 foci and are hypersensitive to PARP inhibitor, whereas forced targeting of PALB2 to DNA breaks in mutant cells circumvents BRCA1 haploinsufficiency. Inhibiting the chromatin ubiquitin pathway may, therefore, be a synthetic lethality strategy for BRCA1-deficient cancers.

A Transplantable Syngeneic Allograft Mouse Model for Nongestational Choriocarcinoma of the Ovary

Nongestational choriocarcinoma is a rare malignancy in humans with poor prognosis. Naturally occurring choriocarcinoma is also rare in laboratory mice, and no genetic mouse model accurately recapitulates the features of this cancer. Here we report development of a genetically engineered mouse (GEM) model with alterations in Brca2, Trp53, and RB that develops ovarian tumors. Most of the ovarian tumors displayed histological characteristics of nongestational choriocarcinoma of the ovary (NGCO) (47%) with abundant syncytiotrophoblasts and cytotrophoblasts, positive immunolabeling for human chorionic gonadotropin, and positive periodic acid-Schiff reaction. The rest of the ovarian tumors were serous epithelial ovarian carcinoma (SEOC) (26%) or mixed tumors consisting of NGCO and SEOC (26%). We further established syngeneic orthotopic mouse models for NGCO by in vivo passaging of GEM tumors. These metastatic models provide a platform for evaluating new treatment strategies in preclinical studies aimed at improving outcomes in choriocarcinoma patients.

A case report on interhemispheric epidermoid tumor

A 30 year old man admitted with the complaints of generalized convulsions, headache and amnesia. The radiological and neuro-pathological findings were interhemispheric epidermoid tumor, which is a rare location. The tumor was removed completely. The diagnosis and management of epidermoid tumors are discussed by reviewing the literature.Pulse Vol.7 January-December 2014 p.46-49

Intratumoral injection of Clostridium novyi-NT spores induces antitumor responses

Species of Clostridium bacteria are notable for their ability to lyse tumor cells growing in hypoxic environments. We show that an attenuated strain of Clostridium novyi (C. novyi-NT) induces a microscopically precise, tumor-localized response in a rat orthotopic brain tumor model after intratumoral injection. It is well known, however, that experimental models often do not reliably predict the responses of human patients to therapeutic agents. We therefore used naturally occurring canine tumors as a translational bridge to human trials. Canine tumors are more like those of humans because they occur in animals with heterogeneous genetic backgrounds, are of host origin, and are due to spontaneous rather than engineered mutations. We found that intratumoral injection of C. novyi-NT spores was well tolerated in companion dogs bearing spontaneous solid tumors, with the most common toxicities being the expected symptoms associated with bacterial infections. Objective responses were observed in 6 of 16 dogs (37.5%), with three complete and three partial responses. On the basis of these encouraging results, we treated a human patient who had an advanced leiomyosarcoma with an intratumoral injection of C. novyi-NT spores. This treatment reduced the tumor within and surrounding the bone. Together, these results show that C. novyi-NT can precisely eradicate neoplastic tissues and suggest that further clinical trials of this agent in selected patients are warranted.

Phenotypes in mTERT⁺/⁻ and mTERT⁻/⁻ mice are due to short telomeres, not telomere-independent functions of telomerase reverse transcriptase

Telomerase is essential for telomere length maintenance. Mutations in either of the two core components of telomerase, telomerase RNA (TR) or the catalytic protein component telomerase reverse transcriptase (TERT), cause the genetic disorders dyskeratosis congenita, pulmonary fibrosis, and other degenerative diseases. Overexpression of the TERT protein has been reported to have telomere length-independent roles, including regulation of the Wnt signaling pathway. To examine the phenotypes of TERT haploinsufficiency and determine whether loss of function of TERT has effects other than those associated with telomere shortening, we characterized both mTERT⁺/⁻ and mTERT⁻/⁻ mice on the CAST/EiJ genetic background. Phenotypic analysis showed a loss of tissue renewal capacity with progressive breeding of heterozygous mice that was indistinguishable from that of mTR-deficient mice. mTERT⁻/⁻ mice, from heterozygous mTERT⁺/⁻ mouse crosses, were born at the expected Mendelian ratio (26.5%; n = 1,080 pups), indicating no embryonic lethality of this genotype. We looked for, and failed to find, hallmarks of Wnt deficiency in various adult and embryonic tissues, including those of the lungs, kidneys, brain, and skeleton. Finally, mTERT⁻/⁻ cells showed wild-type levels of Wnt signaling in vitro. Thus, while TERT overexpression in some settings may activate the Wnt pathway, loss of function in a physiological setting has no apparent effects on Wnt signaling. Our results indicate that both TERT and TR are haploinsufficient and that their deficiency leads to telomere shortening, which limits tissue renewal. Our studies imply that hypomorphic loss-of-function alleles of hTERT and hTR should cause a similar disease spectrum in humans.

Short telomeres are sufficient to cause the degenerative defects associated with aging

Telomerase function is critical for telomere maintenance. Mutations in telomerase components lead to telomere shortening and progressive bone marrow failure in the premature aging syndrome dyskeratosis congenita. Short telomeres are also acquired with aging, yet the role that they play in mediating age-related disease is not fully known. We generated wild-type mice that have short telomeres. In these mice, we identified hematopoietic and immune defects that resembled those present in dyskeratosis congenita patients. When mice with short telomeres were interbred, telomere length was only incrementally restored, and even several generations later, wild-type mice with short telomeres still displayed degenerative defects. Our findings implicate telomere length as a unique heritable trait that, when short, is sufficient to mediate the degenerative defects of aging, even when telomerase is wild-type.

Increased colonic inflammatory injury and formation of aberrant crypt foci in Nrf2-deficient mice upon dextran sulfate treatment

Chronic inflammation has been associated with increased risk of developing cancer. The transcription factor NF-E2-related factor 2 (Nrf2) controls the expression of numerous antioxidative enzymes that have been shown to attenuate acute inflammation. The present study investigated the role of Nrf2 genotype in modulating inflammation-promoted colorectal tumorigenesis. Nrf2 wild-type (WT) and Nrf2-deficient (N0) mice were administered a single dose of azoxymethane followed by a 1-week dose of drinking water with or without 1% dextran sulfate sodium (DSS). Aberrant crypt foci were counted 3 weeks after the cessation of DSS treatment. DSS treatment significantly increased numbers of aberrant crypt foci in N0 mice, but not WT mice. The extent of inflammation over the course of DSS treatment was analyzed in both genotypes. Histological analysis of colon sections revealed that N0 mice had markedly increased inflammation and mucosal damage when compared to WT mice beginning on Day 6 of DSS treatment. Although similar levels of inflammatory and oxidative damage biomarkers were evident in colons from WT and N0 mice at the start of DSS treatment, increased colonic proinflammatory cytokine mRNA transcript levels, myeloperoxidase activity and 3-nitrotyrosine immunoreactivity were observed on Day 6 of DSS treatment in N0 mice, but not WT mice. Additionally, DSS treatment resulted in increased lipid peroxidation and loss of aconitase activity in N0 mice, but not WT mice, reflecting increased oxidative damage in colons from N0 mice. Taken together, these results clearly illustrate the role of Nrf2 in regulating an adaptive response that protects against early-phase inflammation-mediated tumorigenesis.

Serial assessment of human tumor burdens in mice by the analysis of circulating DNA

Internal human xenografts provide valuable animal models to study the microenvironments and metastatic processes occurring in human cancers. However, the use of such models is hampered by the logistical difficulties of reproducibly and simply assessing tumor burden. We developed a high-sensitivity assay for quantifying human DNA in small volumes of mouse plasma, enabling in-life monitoring of systemic tumor burden. Growth kinetics analyses of various xenograft models showed the utility of circulating human DNA as a biomarker. We found that human DNA concentration reproducibly increased with disease progression and decreased after successful therapeutic intervention. A marked, transient spike in circulating human tumor DNA occurred immediately after cytotoxic therapy or surgery. This simple assay may find broad utility in target validation studies and preclinical drug development programs.

Tumor endothelial marker 1 (Tem1) functions in the growth and progression of abdominal tumors

Tumor endothelial marker 1 (Tem1; endosialin) is the prototypical member of a family of genes expressed in the stroma of tumors. To assess the functional role of Tem1, we disrupted the Tem1 gene in mice by targeted homologous recombination. Tem1(-/-) mice were healthy, their wound healing was normal, and tumors grew normally when implanted in s.c. sites. However, there was a striking reduction in tumor growth, invasiveness, and metastasis after transplantation of tumors to abdominal sites in mice without functional Tem1 genes. These data indicate that the stroma can control tumor aggressiveness and that this control varies with anatomic site. Therefore, they have significant implications for the mechanisms underlying tumor invasiveness and for models that evaluate this process.

Short Telomeres, even in the Presence of Telomerase, Limit Tissue Renewal Capacity

Autosomal-dominant dyskeratosis congenita is associated with heterozygous mutations in telomerase. To examine the dosage effect of telomerase, we generated a line of mTR+/- mice on the CAST/EiJ background, which has short telomeres. Interbreeding of heterozygotes resulted in progressive telomere shortening, indicating that limiting telomerase compromises telomere maintenance. In later-generation heterozygotes, we observed a decrease in tissue renewal capacity in the bone marrow, intestines, and testes that resembled defects seen in dyskeratosis congenita patients. The progressive worsening of disease with decreasing telomere length suggests that short telomeres, not telomerase level, cause stem cell failure. Further, wild-type mice derived from the late-generation heterozygous parents, termed wt*, also had short telomeres and displayed a germ cell defect, indicating that telomere length determines these phenotypes. We propose that short telomeres in mice that have normal telomerase levels can cause an occult form of genetic disease.

Pharmacologic and toxicologic evaluation of C. novyi-NT spores

Clostridium novyi-NT (C. novyi-NT) spores have been shown to be potent therapeutic agents in experimental tumors of mice and rabbits. In the present study, pharmacologic and toxicologic studies were performed to better understand the factors influencing the efficacy and toxicity of this form of therapy. We found that spores were rapidly cleared from the circulation by the reticuloendothelial system. Even after large doses were administered, no clinical toxicity was observed in healthy mice or rabbits. The spores were also not toxic in mice harboring poorly vascularized non-neoplastic lesions, including myocardial infarcts. In tumor-bearing mice, toxicity appeared related to tumor size and spore dose, as expected with any bacterial infection. However, there was no laboratory or histopathologic evidence of sepsis, and the toxicity could be effectively controlled by simple hydration.

The Myc target gene JPO1/CDCA7 is frequently overexpressed in human tumors and has limited transforming activity in vivo

MYC is frequently overexpressed in human cancers, but the downstream events contributing to tumorigenesis remain incompletely understood. MYC encodes an oncogenic transcription factor, of which target genes presumably contribute to cellular transformation. Although Myc regulates about 15% of genes and combinations of target genes are likely required for tumorigenesis, we studied in depth the expression of the Myc target gene, JPO1/CDCA7, in human cancers and its ability to provoke tumorigenesis in transgenic mice. JPO1/CDCA7 is frequently overexpressed in human cancers, and in particular, its expression is highly elevated in chronic myelogenous leukemia blast crisis as compared with the chronic phase. In murine lymphoid tissues, ectopic human JPO1/CDCA7 expression resulted in a 2-fold increased risk of lymphoid malignancies at 1 year. The transgene, which was driven by the H2-K promoter, exhibited leaky expression in nonlymphoid tissues such as kidney. We observed a significant increased incidence of transgenic animal solid tumors, which were not seen in littermate controls. These observations suggest that JPO1/CDCA7 may contribute to Myc-mediated tumorigenesis.

Cystic fibrosis in a Bangladeshi child

Cystic fibrosis is one of the common lives limiting inherited diseases in Caucasians population. Recent reports suggest that the diagnosis of cystic fibrosis in this part of the world is missed or delayed due to low index of suspicion. A case of cystic fibrosis is reported here who is a Bangladeshi girl of nine-month-old who presented with the complaints of persistent cough, respiratory distress and failure to thrive. Diagnosis was made on the basis of sweat chloride estimation and mutation analysis, both of which were done, from abroad. She was put on pancreatic enzyme supplementation and nebulized bronchodilators. Cystic fibrosis though rare in Bangladesh its possibility is to be kept in mind in appropriate clinical circumstances

Upper gastrointestinal endoscopy in children - an experience at a paediatric gastroenterology unit

Upper gastrointestinal endoscopy has changed the management of upper gastrointestinal problems in children. The aim of this communication is to share our experience with 153 cases on whom upper gastrointestinal endoscopy was done over a period of 24 months at a paediatric gastroenterology unit of a tertiary care hospital of Dhaka, Bangladesh. Children who attended the department with various gastrointestinal problems are the subjects of this paper. Intravenous midazolam and 10% pharyngeal xylocain were used in majority of cases for sedating the children. The ages of the children were between 15 months to 15 years (9.41+/- 3.22 years). The positive diagnostic yield was 92 out of 153 cases (60.1%). The major indication for doing endoscopy in the present series was recurrent abdominal pain (51.6%), followed by upper gastrointestinal bleeding (28.8%). Combining histopathological findings and CLO/rapid urease tests the overall positive yield of recurrent abdominal pain was 45 out of 79 (57%). The sources of upper gastrointestinal bleeding could be identified in 79.5% cases. Esophageal varices indicating portal hypertension were found in 62.5% children who were endoscoped for unexplained splenomegaly with or without ascitis. Endoscopy has become a safe and valuable procedure in the management of upper gastrointestinal problems in children and gastric antral biopsy has increased the positive diagnostic yield of recurrent abdominal pain in the studied children.

Hepatitis C infection in children: a Melbourne perspective

OBJECTIVE

To examine the clinical spectrum of hepatitis C virus (HCV) infected children in our care by determining presentation, mode of acquisition, degree of co-infection, biochemical evidence of persisting hepatitis and treatment outcome.

METHODOLOGY

A retrospective review of the medical records of all children attending the Royal Children's Hospital, Melbourne, between 1990 and 1998, who had antibodies to HCV infection detected. Detailed clinical information, investigations and the results of treatment were extracted from the clinical notes.

RESULTS

A total of 94 children (age range 2 weeks to 19.7 years) were identified, of whom nine had passive transfer of maternal antibodies from HCV-positive mothers and were excluded from analysis. Sixty-seven children (79%) were infected by transfusion of blood or blood products. Perinatal transmission occurred in 11 children (13%), and six children (7%) had a history of i.v. drug abuse. The majority of children were asymptomatic at presentation. Of the 65 patients tested for HCV-ribonucleic acid, 43 (66%) were positive. Fifty-seven cases had serial alanine aminotransaminase (ALT) measurements over a mean of 28 months. Of these, 38 (67%) had an abnormal ALT. Ten cases (12%) were co-infected with hepatitis B virus, HIV or both. Of 12 patients treated with interferon, four responded with normalisation of ALT from 3 to 12 months post-commencement of therapy.

CONCLUSIONS

Although HCV was largely an asymptomatic condition in our clinic population, more than half the patients had biochemical evidence of ongoing liver damage. Given the chronicity of this infection in the majority of patients and the long-term risks of cirrhosis and hepatocellular carcinoma, children with HCV infection represent a high-risk group worthy of regular follow up.

Four epitopes on tumor necrosis factor-alpha defined by murine anti-tumor necrosis factor-alpha monoclonal antibodies

Eight murine anti-TNF alpha monoclonal antibodies (mAb) were produced after immunization of BALB/c mice with rhTNF alpha. Six of these mAbs were able to neutralize cytotoxic activity of TNF alpha against L929 cells. Two other mAbs had no neutralizing effect. Epitope mapping studies were performed by ELISA and by using a BIAcore system (Pharmacia). The described mAbs were allowed to define 4 different epitopes on TNF alpha. Three of them were involved in the binding of TNF alpha with its receptor (cytotoxic neutralization of TNF alpha). Another epitope was defined by non-neutralizing mAbs.

Bacterially expressed Fabs of monoclonal antibodies neutralizing tumour necrosis factor alpha in vitro retain full binding and biological activity

Antibody fragments specific for the human tumour necrosis factor alpha (TNF alpha) have been cloned from lambda combinatorial expression libraries using total RNA obtained from three different hybridoma cell lines of therapeutic interest. The previously described bacteriophage lambda vectors, lambda HC2 and lambda LC1, were modified to create unique antibody cloning sites in the combinatorial construct and a novel tag peptide was inserted at the C-terminal end of the expressed Fd chain. Sequence analysis of the cloned Fabs indicated that two of them were derived from a single B cell. Expression in E. coli showed that the amount of recovered Fab in the bacterial culture medium was related to the sequences of the variable coding regions. Hybrid Fabs created by chain exchange of similar antibodies were as active as the originally paired Fabs in binding assays. The relative affinities and the capacities of the bacterially expressed Fabs to neutralize TNF alpha cytotoxicity in vitro were identical to those of the parental antibodies. The results demonstrate that, using an in vitro approach, it is possible to generate from existing hybridoma cell lines high affinity Fabs which retain antigen specificity. The cloning sites incorporated into the C-terminal parts of these Fabs will now permit their further modification to include additional functional characteristics not possible with the original hybridoma antibodies.

Photolabeling of erythrocyte and adipocyte hexose transporters using a benzophenone derivative of bis(D-mannose)

The benzophenone derivative of 1,3-bis(D-mannos-4-yloxy)-2-propylamine (BB-BMPA) has been tested as an exofacial photoaffinity label for the sugar transport systems of human erythrocytes and rat adipocytes. The half-maximal inhibition constants for the reagent are 971 microM in erythrocytes and 536 microM in basal and 254 microM in insulin-treated adipocytes. The photolabelling of erythrocyte membranes is very specific for the 50 kDa transporter peptide and is completely displaced by D-glucose. The exofacial photoaffinity labelling of adipocytes also shows labelling of a 50 kDa transporter peptide, which is displaced by cytochalasin B, but extensive nonspecific labelling of a 75 kDa plasma membrane peptide occurs. The transporter is labelled in insulin-treated cells but not in basal cells which indicates that this in situ labelling technique selectively reveals only those transporters that visit and are active in the plasma membrane during the labelling period. This also indicates that in basal cells transporters do not turn over rapidly. Subcellular redistribution of transporters after the labelling period has been studied. Following incubation and washing at 37 degrees C in the presence of insulin, 30% of the transporters photolabelled at the plasma membrane are internalised and are found in the light microsome fraction of the cell. The proportion of transporter that is observed to be internalised is much greater than can be accounted for by a contamination of the light microsome fraction by plasma membrane. The labelled 50 kDa transporter peptide in the light microsomes is enriched when compared with the carry-over of the 75 kDa nonspecifically labelled plasma membrane peptide. Thus we have obtained direct evidence for transporter translocation.