Identification of acquired Notch3 dependency in metastatic Head and Neck Cancer

During cancer development, tumor cells acquire changes that enable them to invade surrounding tissues and seed metastasis at distant sites. These changes contribute to the aggressiveness of metastatic cancer and interfere with success of therapy. Our comprehensive analysis of "matched" pairs of HNSCC lines derived from primary tumors and corresponding metastatic sites identified several components of Notch3 signaling that are differentially expressed and/or altered in metastatic lines and confer a dependency on this pathway. These components were also shown to be differentially expressed between early and late stages of tumors in a TMA constructed from over 200 HNSCC patients. Finally, we show that suppression of Notch3 improves survival in mice in both subcutaneous and orthotopic models of metastatic HNSCC. Novel treatments targeting components of this pathway may prove effective in targeting metastatic HNSCC cells alone or in combination with conventional therapies.

Repurposing Itraconazole and Hydroxychloroquine to Target Lysosomal Homeostasis in Epithelial Ovarian Cancer

Drug repurposing is an attractive option for oncology drug development. Itraconazole is an antifungal ergosterol synthesis inhibitor that has pleiotropic actions including cholesterol antagonism, inhibition of Hedgehog and mTOR pathways. We tested a panel of 28 epithelial ovarian cancer (EOC) cell lines with itraconazole to define its spectrum of activity. To identify synthetic lethality in combination with itraconazole, a whole-genome drop-out genome-scale clustered regularly interspaced short palindromic repeats sensitivity screen in two cell lines (TOV1946 and OVCAR5) was performed. On this basis, we conducted a phase I dose-escalation study assessing the combination of itraconazole and hydroxychloroquine in patients with platinum refractory EOC (NCT03081702). We identified a wide spectrum of sensitivity to itraconazole across the EOC cell lines. Pathway analysis showed significant involvement of lysosomal compartments, the trans-golgi network and late endosomes/lysosomes; similar pathways are phenocopied by the autophagy inhibitor, chloroquine. We then demonstrated that the combination of itraconazole and chloroquine displayed Bliss defined synergy in EOC cancer cell lines. Furthermore, there was an association of cytotoxic synergy with the ability to induce functional lysosome dysfunction, by chloroquine. Within the clinical trial, 11 patients received at least one cycle of itraconazole and hydroxychloroquine. Treatment was safe and feasible with the recommended phase II dose of 300 and 600 mg twice daily, respectively. No objective responses were detected. Pharmacodynamic measurements on serial biopsies demonstrated limited pharmacodynamic impact. In vitro, itraconazole and chloroquine have synergistic activity and exert a potent antitumor effect by affecting lysosomal function. The drug combination had no clinical antitumor activity in dose escalation.

Significance

The combination of the antifungal drug itraconazole with antimalarial drug hydroxychloroquine leads to a cytotoxic lysosomal dysfunction, supporting the rational for further research on lysosomal targeting in ovarian cancer.

Transcriptome-Wide Off-Target Effects of Steric-Blocking Oligonucleotides

Steric-blocking oligonucleotides (SBOs) are short, single-stranded nucleic acids designed to modulate gene expression by binding to RNA transcripts and blocking access from cellular machinery such as splicing factors. SBOs have the potential to bind to near-complementary sites in the transcriptome, causing off-target effects. In this study, we used RNA-seq to evaluate the off-target differential splicing events of 81 SBOs and differential expression events of 46 SBOs. Our results suggest that differential splicing events are predominantly hybridization driven, whereas differential expression events are more common and driven by other mechanisms (including spurious experimental variation). We further evaluated the performance of in silico screens for off-target splicing events, and found an edit distance cutoff of three to result in a sensitivity of 14% and false discovery rate (FDR) of 99%. A machine learning model incorporating splicing predictions substantially improved the ability to prioritize low edit distance hits, increasing sensitivity from 4% to 26% at a fixed FDR of 90%. Despite these large improvements in performance, this approach does not detect the majority of events at an FDR <99%. Our results suggest that in silico methods are currently of limited use for predicting the off-target effects of SBOs, and experimental screening by RNA-seq should be the preferred approach.

Emergence of Enzalutamide Resistance in Prostate Cancer is Associated with BCL-2 and IKKB Dependencies

PURPOSE

Although enzalutamide (ENZ) has been widely used to treat de novo or castration-resistant metastatic prostate cancer, resistance develops and disease progression is ultimately inevitable. There are currently no approved targeted drugs to specifically delay or overcome ENZ resistance.

EXPERIMENTAL DESIGN

We selected several ENZ-resistant cell lines that replicated clinical characteristics of the majority of patients with ENZ-resistant disease. A high-throughput pharmacologic screen was utilized to identify compounds with greater cytotoxic effect for ENZ-resistant cell lines, compared with parental ENZ-sensitive cells. We validated the potential hits in vitro and in vivo, and used knockdown and overexpression assays to study the dependencies in ENZ-resistant prostate cancer.

RESULTS

ABT199 (BCL-2 inhibitor) and IMD0354 (IKKB inhibitor) were identified as potent and selective inhibitors of cell viability in ENZ-resistant cell lines in vitro and in vivo which were further validated using loss-of-function assays of BCL-2 and IKKB. Notably, we observed that overexpression of BCL-2 and IKKB in ENZ-sensitive cell lines was sufficient for the emergence of ENZ resistance. In addition, we confirmed that BCL-2 or IKKB inhibitors suppressed the development of ENZ resistance in xenografts. However, validation of both BCL-2 and IKKB in matched castration-sensitive/resistant clinical samples showed that, concurrent with the development of ENZ/abiraterone resistance in patients, only the protein levels of IKKB were increased.

CONCLUSIONS

Our findings identify BCL-2 and IKKB dependencies in clinically relevant ENZ-resistant prostate cancer cells in vitro and in vivo, but indicate that IKKB upregulation appears to have greater relevance to the progression of human castrate-resistant prostate cancer.

ATP7B variant c.1934T > G p.Met645Arg causes Wilson disease by promoting exon 6 skipping

Wilson disease is a recessive genetic disorder caused by pathogenic loss-of-function variants in the ATP7B gene. It is characterized by disrupted copper homeostasis resulting in liver disease and/or neurological abnormalities. The variant NM_000053.3:c.1934T > G (Met645Arg) has been reported as compound heterozygous, and is highly prevalent among Wilson disease patients of Spanish descent. Accordingly, it is classified as pathogenic by leading molecular diagnostic centers. However, functional studies suggest that the amino acid change does not alter protein function, leading one ClinVar submitter to question its pathogenicity. Here, we used a minigene system and gene-edited HepG2 cells to demonstrate that c.1934T > G causes ~70% skipping of exon 6. Exon 6 skipping results in frameshift and stop-gain, leading to loss of ATP7B function. The elucidation of the mechanistic effect for this variant resolves any doubt about its pathogenicity and enables the development of genetic medicines for restoring correct splicing.

Functional CRISPR and shRNA Screens Identify Involvement of Mitochondrial Electron Transport in the Activation of Evofosfamide

Evofosfamide (TH-302) is a hypoxia-activated DNA-crosslinking prodrug currently in clinical development for cancer therapy. Oxygen-sensitive activation of evofosfamide depends on one-electron reduction, yet the reductases that catalyze this process in tumors are unknown. We used RNA sequencing, whole-genome CRISPR knockout, and reductase-focused short hairpin RNA screens to interrogate modifiers of evofosfamide activation in cancer cell lines. Involvement of mitochondrial electron transport in the activation of evofosfamide and the related nitroaromatic compounds EF5 and FSL-61 was investigated using 143B ρ ⁰ (ρ zero) cells devoid of mitochondrial DNA and biochemical assays in UT-SCC-74B cells. The potency of evofosfamide in 30 genetically diverse cancer cell lines correlated with the expression of genes involved in mitochondrial electron transfer. A whole-genome CRISPR screen in KBM-7 cells identified the DNA damage-response factors SLX4IP, C10orf90 (FATS), and SLFN11, in addition to the key regulator of mitochondrial function, YME1L1, and several complex I constituents as modifiers of evofosfamide sensitivity. A reductase-focused shRNA screen in UT-SCC-74B cells similarly identified mitochondrial respiratory chain factors. Surprisingly, 143B ρ ⁰ cells showed enhanced evofosfamide activation and sensitivity but had global transcriptional changes, including increased expression of nonmitochondrial flavoreductases. In UT-SCC-74B cells, evofosfamide oxidized cytochromes a, b, and c and inhibited respiration at complexes I, II, and IV without quenching reactive oxygen species production. Our results suggest that the mitochondrial electron transport chain contributes to evofosfamide activation and that predicting evofosfamide sensitivity in patients by measuring the expression of canonical bioreductive enzymes such as cytochrome P450 oxidoreductase is likely to be futile.

Identification of P450 Oxidoreductase as a Major Determinant of Sensitivity to Hypoxia-Activated Prodrugs

Hypoxia is a prevalent feature of many tumors contributing to disease progression and treatment resistance, and therefore constitutes an attractive therapeutic target. Several hypoxia-activated prodrugs (HAP) have been developed, including the phase III candidate TH-302 (evofosfamide) and the preclinical agent SN30000, which is an optimized analogue of the well-studied HAP tirapazamine. Experience with this therapeutic class highlights an urgent need to identify biomarkers of HAP sensitivity, including enzymes responsible for prodrug activation during hypoxia. Using genome-scale shRNA screens and a high-representation library enriched for oxidoreductases, we identified the flavoprotein P450 (cytochrome) oxidoreductase (POR) as the predominant determinant of sensitivity to SN30000 in three different genetic backgrounds. No other genes consistently modified SN30000 sensitivity, even within a POR-negative background. Knockdown or genetic knockout of POR reduced SN30000 reductive metabolism and clonogenic cell death and similarly reduced sensitivity to TH-302 under hypoxia. A retrospective evaluation of head and neck squamous cell carcinomas showed heterogeneous POR expression and suggested a possible relationship between human papillomavirus status and HAP sensitivity. Taken together, our study identifies POR as a potential predictive biomarker of HAP sensitivity that should be explored during the clinical development of SN30000, TH-302, and other hypoxia-directed agents.

Suppression of Hepatocellular Carcinoma by Inhibition of Overexpressed Ornithine Aminotransferase

Hepatocellular carcinoma is the second leading cause of cancer death worldwide. DNA microarray analysis identified the ornithine aminotransferase (OAT) gene as a prominent gene overexpressed in hepatocellular carcinoma (HCC) from Psammomys obesus. In vitro studies demonstrated inactivation of OAT by gabaculine (1), a neurotoxic natural product, which suppressed in vitro proliferation of two HCC cell lines. Alpha-fetoprotein (AFP) secretion, a biomarker for HCC, was suppressed by gabaculine in both cell lines, but not significantly. Because of the active site similarity between GABA aminotransferase (GABA-AT) and OAT, a library of 24 GABA-AT inhibitors was screened to identify a more selective inhibitor of OAT. (1S,3S)-3-Amino-4-(hexafluoropropan-2-ylidene)cyclopentane-1-carboxylic acid (2) was found to be an inactivator of OAT that only weakly inhibits GABA-AT, l-aspartate aminotransferase, and l-alanine aminotransferase. In vitro administration of 2 significantly suppressed AFP secretion in both Hep3B and HepG2 HCC cells; in vivo, 2 significantly suppressed AFP serum levels and tumor growth in HCC-harboring mice, even at 0.1 mg/kg. Overexpression of the OAT gene in HCC and the ability to block the growth of HCC by OAT inhibitors support the role of OAT as a potential therapeutic target to inhibit HCC growth. This is the first demonstration of suppression of HCC by an OAT inactivator.

β-glycosphingolipids ameliorated non-alcoholic steatohepatitis in the Psammomys obesus model

Liver steatosis is a common characteristic of obesity and type 2 diabetes, and fatty liver disease is increasingly recognized as a major health burden. Accumulating evidence suggests that β-glycosphingolipids play an important role in insulin sensitivity and thus could affect hepatic steatosis. To determine the effect associated with β-glycosphingolipid-mediated amelioration of liver injury, seven groups of Psammomys obesus on a high-energy diet were studied. Animals were treated with daily injections of β-glucosylceramide, β-lactosylceramide, or a combination of both. β-glycosphingolipids ameliorated the hepatic injury manifested by decreased liver enzymes, liver weight, and hepatic fat, and improved liver histology. Administration of both β-glucosylceramide and β-lactosylceramide also decreased interferon (IFN)-γ serum levels. These effects were associated with improved serum cholesterol and triglyceride levels. These data suggest that β-glycosphingolipids ameliorate liver injury in an animal model of nonalcoholic steatohepatitis.

Amelioration of hepatic fibrosis via beta-glucosylceramide-mediated immune modulation is associated with altered CD8 and NKT lymphocyte distribution

BACKGROUND

While CD8 lymphocytes possess pro-fibrogenic properties and NK (non-T) cells are anti-fibrogenic, the role of NKT lymphocytes in liver fibrosis is still unclear. Beta-glucosylceramide (GC), a naturally occurring glycolipid, exerts modulatory effects on these cells.

AIM

To explore the role of NKT cells in hepatic fibrosis via GC.

METHODS

Hepatic fibrosis was induced by biweekly intra-peritoneal (IP) carbon tetrachloride (CCl(4)) administrations for 7 weeks in 5 groups (A-E) of male C57Bl/6 mice. Mice were treated with daily IP GC injections in groups A and C, or daily oral doses in groups B and D. GC was administered either for the duration of the study period (in groups A and B), or for the last 3 weeks of CCl(4) induction (groups C and D). GC-treated mice were compared with non-treated fibrotic controls (group E) and naive rodents (group F). Liver fibrosis, injury parameters and FACS analysis of lymphocytes were assessed.

RESULTS

Marked amelioration (P < 0.0001) of hepatic fibrosis observed in all GC-treated mice without altering reactive oxygen species production. As determined by Sirius red-stained liver tissue sections and measured by Bioquant morphometry; all CCl(4)-administered groups significantly (P < 0.0001) increased the relative fibrosis area compared with naive animals. The increases were 14.4 +/- 1.03-fold in group A, 7.9 +/- 0.37-fold in group B, 5.2 +/- 0.2-fold in group C, 10.3 +/- 0.4-fold in group D and 23.8 +/- 1.9-fold in group E. Western blot analysis for alpha smooth muscle actin from liver extracts followed a similar pattern, increasing in groups A-E. A significant decrease in liver damage was observed in all GC-treated groups, as noted by a decrease in transaminase serum levels (P < 0.005). The beneficial effect of GC was associated with a significant decrease in the intra-hepatic NKT and CD8 lymphocytes as well as their attenuation of both T(h)1 and T(h)2 cytokines.

CONCLUSIONS

Administration of GC had a significant anti-fibrotic effect following CCl(4) administration. This effect was associated with an altered NKT and CD8 lymphocyte distribution and a cytokine shift. Immune modulation using GC may have a role in the treatment of fibrosis and other immune-mediated disorders.

Beta-glucosylceramide: a novel method for enhancement of natural killer T lymphoycte plasticity in murine models of immune-mediated disorders

BACKGROUND

beta-Glucosylceramide, a naturally occurring glycolipid, exerts modulatory effects on natural killer T (NKT) lymphocytes.

AIM

To determine whether beta-glucosylceramide can alter NKT function in opposite directions, colitis was induced by intracolonic installation of trinitrobenzenesulphonic acid, and hepatocellular carcinoma (HCC) was induced by transplantation of Hep3B cells.

METHODS

The immunological effect of beta-glucosylceramide was assessed by analysis of intrahepatic and intrasplenic lymphocyte populations, serum cytokines and STAT protein expression.

RESULTS

Administration of beta-glucosylceramide led to alleviation of colitis and to suppression of HCC, manifested by improved survival and decreased tumour volume. The beneficial effects were associated with an opposite immunological effect in the two models: the peripheral:intrahepatic CD4:CD8 lymphocyte ratio increased in the colitis model and decreased in the HCC group. The peripheral:intrahepatic NKT lymphocyte ratio decreased in beta-glucosylceramide-treated mice solely in the HCC model. The effect of beta-glucosylceramide was associated with decreased STAT1 and 4 expression, and with overexpression of STAT6, along with decreased interferon gamma levels in the colitis model, whereas an opposite effect was noted in the HCC model.

CONCLUSIONS

beta-glucosylceramide alleviates immunologically incongruous disorders and may be associated with "fine tuning" of immune responses, by changes in plasticity of NKT lymphocytes.

Glucocerebroside ameliorates the metabolic syndrome in OB/OB mice

Glucocerebroside (GC) is a naturally occurring glycolipid that may alter natural killer T (NKT) cell function. To determine the effect of GC on the metabolic derangements and immune profile in leptin-deficient mice, Ob/Ob mice were treated by daily injections of GC for 8 weeks and followed for various metabolic and immunological parameters. Marked amelioration of the metabolic alterations characteristic of leptin-deficient mice was observed in GC-treated animals compared with controls. A significant decrease in liver size and hepatic fat content were observed in GC-treated mice. Near-normalization of glucose tolerance and decreased serum triglyceride levels were observed. Fluorescence-activated cell sorting analysis of peripheral and intrahepatic lymphocytes revealed a 1.6-fold increase of the peripheral/intrahepatic NKT lymphocyte ratio. A 33% decrease of serum interferon-gamma level and a 2.6-fold increase of serum interleukin 10 level were noted in GC-treated mice. Immune modulation by GC may have a role in the treatment of nonalcoholic steatohepatitis and other immune-mediated disorders.

Molecular characterization of three novel Fanconi anemia mutations in Israeli Arabs

OBJECTIVES

In a previous study, we investigated the molecular basis of Fanconi anemia (FA) in 13 unrelated Israeli Jewish FA patients and identified four ethnicity specific mutations. In the present study we extended our study to Israeli Arab patients.

METHODS

We studied three consanguineous families with nine FA patients and an additional unrelated patient. DNA single-strand conformation polymorphism of each exon of the FANCA and FANCG genes was followed by sequence analysis of the aberrantly migrating fragments and by reverse transcriptase-polymerase chain reaction (RT-PCR) analysis of the splice-site mutations identified.

RESULTS

Three unique disease-causing mutations were identified: (i) FANCA gross deletion of exons 6-31; (ii) FANCA splice-site mutation IVS 42-2A>C; (iii) FANCG splice-site mutation IVS4+3A>G. Sequence analysis of the FANCA gross deletion revealed recombination between two highly homologous Alu elements. cDNA analysis of the two splice mutations suggested intron 42 retention in FANCA IVS 42-2A>C and exon 4 skipping in FANCG IVS4+3A>G. The clinical condition of eight patients with FANCA mutations was severe.

CONCLUSIONS

Two unique FANCA mutations and one FANCG mutation were identified in Israeli Arab FA patients. Deletion of FANCA exon 6-31 as in previously described gross deletions was within introns rich in Alu repeats. To the best of our knowledge, the FANCA IVS 42-2A>C mutation is the first in this gene to result in intron retention. Further analysis of FA mutations will enable prenatal diagnosis and a rational therapeutic approach including frequent monitoring and early bone marrow transplantation.

A clinical and molecular study of a Bedouin family with dysmegakaryopoiesis, mild anemia, and neutropenia cured by bone marrow transplantation

OBJECTIVES

Familial thrombocytopenia is a relatively rare and heterogeneous group of clinical and genetic syndromes of unknown etiology. Recently, mutations in a few hematopoietic transcription factors were implicated in dysmegakaryopoiesis with and without dyserythropoietic anemia. The aim of the present study was to describe the clinical and hematologic picture of members of a Bedouin family with severe congenital thrombocytopenia associated with neutropenia and anemia and to determine the possible involvement of hematopoietic transcription factor genes in their disease.

PATIENTS AND METHODS

Four members of a Bedouin family presented with severe bleeding tendency, including intracranial hemorrhage in three. Three of the four were successfully treated with allogenic human leukocyte antigen (HLA)-matched bone marrow transplants. Measurements of serum erythropoietin and thrombopoietin levels, bone marrow electron microscopy, and megakaryocytic colony were grown for each patient in addition to DNA amplification and single-strand conformation polymorphism of each exon of the NF-E2, Fli-1, FOG-1, and Gfi-1b in genes.

RESULTS

Bone marrow studies revealed dysmegakaryopoiesis and mild dyserythropoiesis. A low number of bone marrow megakaryocyte colony-forming units was found, as well as a slightly elevated serum thrombopoietin level. No mutation was identified in any of the transcription factor genes examined.

CONCLUSIONS

A unique autosomal recessive bone marrow disorder with prominent involvement of megakaryocytes is described. Defects were not identified in transcription factors affecting the common myeloid progenitor.

Survival in Soil of Colletotrichum acutatum and C. gloeosporioides Pathogenic on Strawberry

The survival ability in soil of different inocula of strawberry isolates of Colletotrichum gloeosporioides and C. acutatum was studied under laboratory and field conditions. Two isolates of each species used in this study were identified according to morphological characteristics and by molecular techniques. Conidia of all four isolates survived for up to 1 year in autoclaved soil, whereas viability declined rapidly in untreated soils at 22% soil moisture (field capacity), with a 95% reduction in population recorded within 4.0 to 9.8 days. In methyl bromide (MB)-treated field soil at field capacity, a 95% decline in the viability of conidia of the two species was recorded within 8.9 to 12.9 days. At 11% soil moisture content, the time required for a 95% population reduction of the isolates of C. gloeosporioides and C. acutatum conidia was 124.5 and 114.4, and 72.8 and 74.2 days, respectively. C. acutatum was not recovered from naturally infected crowns after burial for 5 months in MB-fumigated and untreated soils at 10- and 20-cm depths under field conditions, but the decline was slower in the MB-fumigated soil. However, recovery of the pathogen from artificially inoculated mummified fruit after 5 months of burial ranged from 15 to 39%. Soil solarization for 4 weeks and MB fumigation treatments eradicated the pathogen from buried, artificially inoculated fruits. Based on this study, the potential contribution of conidia as well as mummified fruits to disease epidemics should be considered.

Sonographic growth curves of triplet conceptions

The diagnosis of inappropriate intrauterine fetal growth in triplet pregnancies requires normal standard sonographically determined growth curves. The aim of the present study was to establish such nomograms. The biparietal diameter (BPD), femur length, head and abdominal circumferences (HC, AC) were once in 3 weeks sonographically evaluated in 108 normal triplet fetuses. The resulting growth curves were compared with those of normal singleton fetuses. The data showed that, compared with singletons, the mean triplet fetal BPD progressively lags to a maximum of 2 1/2 weeks as pregnancy continuous from the 25th to the 36th gestational week. Similarly, mean femur length of triplet fetuses gradually shortfalls to the greatest of 2 weeks as gestation advances from the 25th to the 36th week. HC to AC ratio of the triplet fetuses does not differ from the singletons curve. It may be concluded that a normal fetal growth curve in triplet pregnancies demonstrates a 1- to 3-week delay compared with singleton gestations.