Dietary fibre supplementation enhances radiotherapy tumour control and alleviates intestinal radiation toxicity.

BACKGROUND: Non-toxic approaches to enhance radiotherapy outcomes are beneficial, particularly in ageing populations. Based on preclinical findings showing that high-fibre diets sensitised bladder tumours to irradiation by modifying the gut microbiota, along with clinical evidence of prebiotics enhancing anti-cancer immunity, we hypothesised that dietary fibre and its gut microbiota modification can radiosensitise tumours via secretion of metabolites and/or immunomodulation. We investigated the efficacy of high-fibre diets combined with irradiation in immunoproficient C57BL/6 mice bearing bladder cancer flank allografts. RESULT: Psyllium plus inulin significantly decreased tumour size and delayed tumour growth following irradiation compared to 0.2% cellulose and raised intratumoural CD8+ cells. Post-irradiation, tumour control positively correlated with Lachnospiraceae family abundance. Psyllium plus resistant starch radiosensitised the tumours, positively correlating with Bacteroides genus abundance and increased caecal isoferulic acid levels, associated with a favourable response in terms of tumour control. Psyllium plus inulin mitigated the acute radiation injury caused by 14 Gy. Psyllium plus inulin increased caecal acetate, butyrate and propionate levels, and psyllium alone and psyllium plus resistant starch increased acetate levels. Human gut microbiota profiles at the phylum level were generally more like mouse 0.2% cellulose profiles than high fibre profiles. CONCLUSION: These supplements may be useful in combination with radiotherapy in patients with pelvic malignancy. Video Abstract.

Venomous gland transcriptome and venom proteomic analysis of the scorpion Androctonus amoreuxi reveal new peptides with anti-SARS-CoV-2 activity.

The recent COVID-19 pandemic shows the critical need for novel broad spectrum antiviral agents. Scorpion venoms are known to contain highly bioactive peptides, several of which have demonstrated strong antiviral activity against a range of viruses. We have generated the first annotated reference transcriptome for the Androctonus amoreuxi venom gland and used high performance liquid chromatography, transcriptome mining, circular dichroism and mass spectrometric analysis to purify and characterize twelve previously undescribed venom peptides. Selected peptides were tested for binding to the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein and inhibition of the spike RBD - human angiotensin-converting enzyme 2 (hACE2) interaction using surface plasmon resonance-based assays. Seven peptides showed dose-dependent inhibitory effects, albeit with IC50 in the high micromolar range (117-1202 µM). The most active peptide was synthesized using solid phase peptide synthesis and tested for its antiviral activity against SARS-CoV-2 (Lineage B.1.1.7). On exposure to the synthetic peptide of a human lung cell line infected with replication-competent SARS-CoV-2, we observed an IC50 of 200 nM, which was nearly 600-fold lower than that observed in the RBD - hACE2 binding inhibition assay. Our results show that scorpion venom peptides can inhibit the SARS-CoV-2 replication although unlikely through inhibition of spike RBD - hACE2 interaction as the primary mode of action. Scorpion venom peptides represent excellent scaffolds for design of novel anti-SARS-CoV-2 constrained peptides. Future studies should fully explore their antiviral mode of action as well as the structural dynamics of inhibition of target virus-host interactions.

Homemade Nucleic Acid Preservation Buffer Proves Effective in Preserving the Equine Faecal Microbiota over Time at Ambient Temperatures.

The equine faecal microbiota is often assessed as a proxy of the microbial community in the distal colon, where the microbiome has been linked to states of health and disease in the horse. However, the microbial community structure may change over time if samples are not adequately preserved. This study stored equine faecal samples from n = 10 horses in four preservation treatments at room temperature for up to 150 h and assessed the resulting impact on microbial diversity and the differential abundance of taxa. Treatments included "COLD" (samples packaged with a cool pack), "CLX" (2% chlorhexidine digluconate solution), "NAP" (nucleic acid preservation buffer), and "FTA" (Whatman FTA™ cards). The samples were assessed using 16S rRNA gene sequencing after storage for 0, 24, 72, and 150 h at room temperature under the different treatments. The results showed effective preservation of diversity and community structure with NAP buffer but lower diversity (p = 0.001) and the under-representation of Fibrobacterota in the FTA card samples. The NAP treatment inhibited the overgrowth of bloom taxa that occurred by 72 h at room temperature. The COLD, CLX, and NAP treatments were effective in preserving the faecal microbiota for up to 24 h at room temperature, and the CLX and NAP treatments improved the yield of Patescibacteria and Fibrobacterota in some cases. The cold and CLX treatments were ineffective in preventing community shifts that occurred by 72 h at room temperature. These findings demonstrate the suitability of the COLD, NAP, and CLX treatments for the room temperature storage of equine faeces for up to 24 h and of NAP buffer for up to 150 h prior to processing.

Taxonomy of fibroblasts and progenitors in the synovial joint at single-cell resolution.

OBJECTIVES: Fibroblasts in synovium include fibroblast-like synoviocytes (FLS) in the lining and Thy1+ connective-tissue fibroblasts in the sublining. We aimed to investigate their developmental origin and relationship with adult progenitors. METHODS: To discriminate between Gdf5-lineage cells deriving from the embryonic joint interzone and other Pdgfrα-expressing fibroblasts and progenitors, adult Gdf5-Cre;Tom;Pdgfrα-H2BGFP mice were used and cartilage injury was induced to activate progenitors. Cells were isolated from knees, fibroblasts and progenitors were sorted by fluorescence-activated cell-sorting based on developmental origin, and analysed by single-cell RNA-sequencing. Flow cytometry and immunohistochemistry were used for validation. Clonal-lineage mapping was performed using Gdf5-Cre;Confetti mice. RESULTS: In steady state, Thy1+ sublining fibroblasts were of mixed ontogeny. In contrast, Thy1-Prg4+ lining fibroblasts predominantly derived from the embryonic joint interzone and included Prg4-expressing progenitors distinct from molecularly defined FLS. Clonal-lineage tracing revealed compartmentalisation of Gdf5-lineage fibroblasts between lining and sublining. Following injury, lining hyperplasia resulted from proliferation and differentiation of Prg4-expressing progenitors, with additional recruitment of non-Gdf5-lineage cells, into FLS. Consistent with this, a second population of proliferating cells, enriched near blood vessels in the sublining, supplied activated multipotent cells predicted to give rise to Thy1+ fibroblasts, and to feed into the FLS differentiation trajectory. Transcriptional programmes regulating fibroblast differentiation trajectories were uncovered, identifying Sox5 and Foxo1 as key FLS transcription factors in mice and humans. CONCLUSIONS: Our findings blueprint a cell atlas of mouse synovial fibroblasts and progenitors in healthy and injured knees, and provide novel insights into the cellular and molecular principles governing the organisation and maintenance of adult synovial joints.

ß-Glucan is a major growth substrate for human gut bacteria related to Coprococcus eutactus.

A clone encoding carboxymethyl cellulase activity was isolated during functional screening of a human gut metagenomic library using Lactococcus lactis MG1363 as heterologous host. The insert carried a glycoside hydrolase family 9 (GH9) catalytic domain with sequence similarity to a gene from Coprococcus eutactus ART55/1. Genome surveys indicated a limited distribution of GH9 domains among dominant human colonic anaerobes. Genomes of C. eutactus-related strains harboured two GH9-encoding and four GH5-encoding genes, but the strains did not appear to degrade cellulose. Instead, they grew well on ß-glucans and one of the strains also grew on galactomannan, galactan, glucomannan and starch. Coprococcus comes and Coprococcus catus strains did not harbour GH9 genes and were not able to grow on ß-glucans. Gene expression and proteomic analysis of C. eutactus ART55/1 grown on cellobiose, ß-glucan and lichenan revealed similar changes in expression in comparison to glucose. On ß-glucan and lichenan only, one of the four GH5 genes was strongly upregulated. Growth on glucomannan led to a transcriptional response of many genes, in particular a strong upregulation of glycoside hydrolases involved in mannan degradation. Thus, ß-glucans are a major growth substrate for species related to C. eutactus, with glucomannan and galactans alternative substrates for some strains.

VGLL3 operates via TEAD1, TEAD3 and TEAD4 to influence myogenesis in skeletal muscle.

VGLL proteins are transcriptional co-factors that bind TEAD family transcription factors to regulate events ranging from wing development in fly, to muscle fibre composition and immune function in mice. Here, we characterise Vgll3 in skeletal muscle. We found that mouse Vgll3 was expressed at low levels in healthy muscle but that its levels increased during hypertrophy or regeneration; in humans, VGLL3 was highly expressed in tissues from patients with various muscle diseases, such as in dystrophic muscle and alveolar rhabdomyosarcoma. Interaction proteomics revealed that VGLL3 bound TEAD1, TEAD3 and TEAD4 in myoblasts and/or myotubes. However, there was no interaction with proteins from major regulatory systems such as the Hippo kinase cascade, unlike what is found for the TEAD co-factors YAP (encoded by YAP1) and TAZ (encoded by WWTR1). Vgll3 overexpression reduced the activity of the Hippo negative-feedback loop, affecting expression of muscle-regulating genes including Myf5, Pitx2 and Pitx3, and genes encoding certain Wnts and IGFBPs. VGLL3 mainly repressed gene expression, regulating similar genes to those regulated by YAP and TAZ. siRNA-mediated Vgll3 knockdown suppressed myoblast proliferation, whereas Vgll3 overexpression strongly promoted myogenic differentiation. However, skeletal muscle was overtly normal in Vgll3-null mice, presumably due to feedback signalling and/or redundancy. This work identifies VGLL3 as a transcriptional co-factor operating with the Hippo signal transduction network to control myogenesis.

Formate cross-feeding and cooperative metabolic interactions revealed by transcriptomics in co-cultures of acetogenic and amylolytic human colonic bacteria.

Interspecies cross-feeding is a fundamental factor in anaerobic microbial communities. In the human colon, formate is produced by many bacterial species but is normally detected only at low concentrations. Ruminococcus bromii produces formate, ethanol and acetate in approximately equal molar proportions in pure culture on RUM-RS medium with 0.2% Novelose resistant starch (RS3) as energy source. Batch co-culturing on starch with the acetogen Blautia hydrogenotrophica however led to the disappearance of formate and increased levels of acetate, which is proposed to occur through the routing of formate via the Wood Ljungdahl pathway of B. hydrogenotrophica. We investigated these inter-species interactions further using RNAseq to examine gene expression in continuous co-cultures of R. bromii and B. hydrogenotrophica. Transcriptome analysis revealed upregulation of B. hydrogenotrophica genes involved in the Wood-Ljungdahl pathway and of a 10 gene cluster responsible for increased branched chain amino acid fermentation in the co-cultures. Cross-feeding between formate-producing species and acetogens may be a significant factor in short chain fatty acid formation in the colon contributing to high rates of acetate production. Transcriptome analysis also indicated competition for the vitamin thiamine and downregulation of dissimilatory sulfate reduction and key redox proteins in R. bromii in the co-cultures, thus demonstrating the wide-ranging consequences of inter-species interactions in this model system.

Adaptive response of neonatal sepsis-derived Group B Streptococcus to bilirubin.

Hyperbilirubinemia is so common in newborns as to be termed physiological. The most common bacteria involved in early-onset neonatal sepsis are Streptococcus agalactiae, commonly called Group B Streptococcus (GBS). Whilst previous studies show bilirubin has antioxidant properties and is beneficial in endotoxic shock, little thought has been given to whether bilirubin might have antibacterial properties. In this study, we performed a transcriptomic and proteomic assessment of GBS cultured in the presence/absence of bilirubin. Our analysis revealed that increasing levels of bilirubin (>100 µmol/L) negatively correlated with GBS growth (18% reduction from 0-400 µmol/L on plate model, p < 0.001; 33% reduction from 0-100 µmol/L in liquid model, p = 0.02). Transcriptome analysis demonstrated 19 differentially expressed genes, almost exclusively up-regulated in the presence of bilirubin. Proteomic analysis identified 12 differentially expressed proteins, half over-expressed in the presence of bilirubin. Functional analysis using Gene Ontology and KEGG pathways18 revealed a differential expression of genes involved in transport and carbohydrate metabolism, suggesting bilirubin may impact on substrate utilisation. The data improve our understanding of the mechanisms modulating GBS survival in neonatal hyperbilirubinemia and suggest physiological jaundice may have an evolutionary role in protection against early-onset neonatal sepsis.

Common and Distinctive Functions of the Hippo Effectors Taz and Yap in Skeletal Muscle Stem Cell Function.

Hippo pathway downstream effectors Yap and Taz play key roles in cell proliferation and regeneration, regulating gene expression especially via Tead transcription factors. To investigate their role in skeletal muscle stem cells, we analyzed Taz in vivo and ex vivo in comparison with Yap. Small interfering RNA knockdown or retroviral-mediated expression of wild-type human or constitutively active TAZ mutants in satellite cells showed that TAZ promoted proliferation, a function shared with YAP. However, at later stages of myogenesis, TAZ also enhanced myogenic differentiation of myoblasts, whereas YAP inhibits such differentiation. Functionally, while muscle growth was mildly affected in Taz (gene Wwtr1-/- ) knockout mice, there were no overt effects on regeneration. Conversely, conditional knockout of Yap in satellite cells of Pax7Cre-ERT2/+ : Yapfl °x/fl °x :Rosa26Lacz mice produced a regeneration deficit. To identify potential mechanisms, microarray analysis showed many common TAZ/YAP target genes, but TAZ also regulates some genes independently of YAP, including myogenic genes such as Pax7, Myf5, and Myod1 (ArrayExpress-E-MTAB-5395). Proteomic analysis revealed many novel binding partners of TAZ/YAP in myogenic cells, but TAZ also interacts with proteins distinct from YAP that are often involved in myogenesis and aspects of cytoskeleton organization (ProteomeXchange-PXD005751). Neither TAZ nor YAP bind members of the Wnt destruction complex but both regulated expression of Wnt and Wnt-cross talking genes with known roles in myogenesis. Finally, TAZ operates through Tead4 to enhance myogenic differentiation. In summary, Taz and Yap have overlapping functions in promoting myoblast proliferation but Taz then switches to enhance myogenic differentiation. Stem Cells 2017;35:1958-1972.

Regulation of cellular sphingosine-1-phosphate by sphingosine kinase 1 and sphingosine-1-phopshate lyase determines chemotherapy resistance in gastroesophageal cancer.

BACKGROUND: Resistance to chemotherapy is common in gastroesophageal cancer. Mechanisms of resistance are incompletely characterised and there are no predictive biomarkers in clinical practice for cytotoxic drugs. We used new cell line models to characterise novel chemotherapy resistance mechanisms and validated them in tumour specimens to identify new targets and biomarkers for gastroesophageal cancer. METHODS: Cell lines were selected for resistance to oxaliplatin, cisplatin and docetaxel and gene expression examined using Affymetrix Exon 1.0 ST arrays. Leads were validated by qRT-PCR and HPLC of tumour metabolites. Protein expression and pharmacological inhibition of lead target SPHK1 was evaluated in independent cell lines, and by immunohistochemistry in gastroesophageal cancer patients. RESULTS: Genes with differential expression in drug resistant cell lines compared to the parental cell line they were derived from, were identified for each drug resistant cell line. Biological pathway analysis of these gene lists, identified over-represented pathways, and only 3 pathways - lysosome, sphingolipid metabolism and p53 signalling- were identified as over-represented in these lists for all three cytotoxic drugs investigated. The majority of genes differentially expressed in chemoresistant cell lines from these pathways, were involved in metabolism of glycosphingolipids and sphingolipids in lysosomal compartments suggesting that sphingolipids might be important mediators of cytotoxic drug resistance in gastroeosphageal cancers . On further investigation, we found that drug resistance (IC50) was correlated with increased sphingosine kinase 1(SPHK1) mRNA and also with decreased sphingosine-1-phosphate lysase 1(SGPL1) mRNA. SPHK1 and SGPL1 gene expression were inversely correlated. SPHK1:SGPL1 ratio correlated with increased cellular sphingosine-1-phosphate (S1P), and S1P correlated with drug resistance (IC50). High SPHK1 protein correlated with resistance to cisplatin (IC50) in an independent gastric cancer cell line panel and with survival of patients treated with chemotherapy prior to surgery but not in patients treated with surgery alone. Safingol a SPHK1 inhibitor, was cytotoxic as a single agent and acted synergistically with cisplatin in gastric cancer cell lines. CONCLUSION: Agents that inhibit SPHK1 or S1P could overcome cytotoxic drug resistance in gastroesophageal cancer. There are several agents in early phase human trials including Safingol that could be combined with chemotherapy or used in patients progressing after chemotherapy.

Influence of resistance to 5-fluorouracil and tomudex on [18F]­FDG incorporation, glucose transport and hexokinase activity.

Drug resistance is a major obstacle to cancer cure and may influence [18F]-fluorodeoxyglucose (FDG) incorporation. In this study, glucose transport, hexokinase activity and [18F]-FDG incorporation were measured in drug-resistant tumour cells generated by exposing H630 colon and MCF7 breast cancer cells to increasing concentrations of tomudex (raltitrexed) or 5-fluorouracil (5FU). Drug sensitivity was determined using the XTT assay: Tomudex-resistant (H630TDX and MCF7TDX) cells were more than 40,000-fold less sensitive to tomudex than were the parental wild-type, H630WT and MCF7WT cells, respectively. 5FU-resistant (H630R10) cells were 100-fold less sensitive than parental H630WT cells to 5FU. As previously reported for 5FU-resistant MCF7 breast cancer cells, [18F]-FDG incorporation was decreased in H630R10 colon cancer cells compared to the parental line. By contrast, both tomudex-resistant cell lines exhibited increased [18F]-FDG incorporation compared with the parental lines. H630R10 and MCF7TDX cells exhibited higher rates of glucose transport, measured as the initial rate of O-methyl-glucose (OMG) uptake, compared to wild-type cells; however, glucose transport was not significantly different between H630TDX cells and the parental cells. Hexokinase activity was lower in H630R10 and MCF7TDX cells compared with sensitive parental cells but unchanged in H630TDX cells. In conclusion, our results show that [18F]-FDG incorporation is influenced by resistance to antifolate and fluoropyrimidine-based anti-cancer drugs in a drug-dependent manner and the underlying mechanisms appear to be cell- and drug-dependent. Glucose transport may be a useful marker of resistance to 5FU.

SerpinB3, a new prognostic tool in breast cancer patients treated with neoadjuvant chemotherapy.

It is unclear which patients with breast cancer benefit from anthracycline-based neoadjuvant chemotherapy and whether taxanes increase survival. Hsp70 and serpinB3 inhibit a lysosomal cell death pathway induced in anthracycline and taxane treated cells, which may be critical for breast cancer cell survival. Thus we evaluated serpinB3 and Hsp70 as putative prognostic biomarkers in breast cancer patients treated with neoadjuvant chemotherapy. SerpinB3 and Hsp70 were measured by immunohistochemistry in residual breast tumours of patients without a complete pathological response [pCR] (n = 250), from a retrospective cohort of 296 patients treated with anthracycline-based chemotherapy with or without sequential docetaxel prior to surgical resection. SerpinB3 (P = 0.02) and Hsp70 (P = 0.008) positivity in residual tumour were associated with a poor pathological response and serpinB3 was an independent prognostic biomarker (HR 2.1 (95% CI 1.2-3.8), P = 0.02). Docetaxel significantly improved overall survival of breast cancer patients treated with neoadjuvant chemotherapy. Furthermore, serpinB3 positivity predicted poor survival in patients treated with anthracycline-based chemotherapy alone (P = 0.02), but those with serpinB3 negative tumours had as equally good survival as those also treated with docetaxel (P = 0.7). Survival was independent of serpinB3 expression in patients who received sequential docetaxel. The Nottingham prognostic index (NPI), calculated at surgical resection, predicted overall survival in these neoadjuvantly treated patients (P < 0.001) and serpinB3 status segregated patients with a moderate NPI into distinct prognostic subgroups. The use of clinical (NPI) and molecular (serpinB3) biomarkers measured at surgical resection to provide accurate prognostication in patients who do not achieve a pCR following neoadjuvant chemotherapy could facilitate optimal post-operative clinical management of these patients and is of significant clinical value. Furthermore, serpinB3 status in residual tumour is a biomarker of neoadjuvant docetaxel benefit in patients not achieving a pCR and use of serpinB3 molecular subtyping for adjuvant docetaxel treatment planning warrants further investigation.

APRIL is a novel clinical chemo-resistance biomarker in colorectal adenocarcinoma identified by gene expression profiling.

BACKGROUND: 5-Fluorouracil(5FU) and oral analogues, such as capecitabine, remain one of the most useful agents for the treatment of colorectal adenocarcinoma. Low toxicity and convenience of administration facilitate use, however clinical resistance is a major limitation. Investigation has failed to fully explain the molecular mechanisms of resistance and no clinically useful predictive biomarkers for 5FU resistance have been identified. We investigated the molecular mechanisms of clinical 5FU resistance in colorectal adenocarcinoma patients in a prospective biomarker discovery project utilising gene expression profiling. The aim was to identify novel 5FU resistance mechanisms and qualify these as candidate biomarkers and therapeutic targets. METHODS: Putative treatment specific gene expression changes were identified in a transcriptomics study of rectal adenocarcinomas, biopsied and profiled before and after pre-operative short-course radiotherapy or 5FU based chemo-radiotherapy, using microarrays. Tumour from untreated controls at diagnosis and resection identified treatment-independent gene expression changes. Candidate 5FU chemo-resistant genes were identified by comparison of gene expression data sets from these clinical specimens with gene expression signatures from our previous studies of colorectal cancer cell lines, where parental and daughter lines resistant to 5FU were compared. A colorectal adenocarcinoma tissue microarray (n = 234, resected tumours) was used as an independent set to qualify candidates thus identified. RESULTS: APRIL/TNFSF13 mRNA was significantly upregulated following 5FU based concurrent chemo-radiotherapy and in 5FU resistant colorectal adenocarcinoma cell lines but not in radiotherapy alone treated colorectal adenocarcinomas. Consistent with APRIL's known function as an autocrine or paracrine secreted molecule, stromal but not tumour cell protein expression by immunohistochemistry was correlated with poor prognosis (p = 0.019) in the independent set. Stratified analysis revealed that protein expression of APRIL in the tumour stroma is associated with survival in adjuvant 5FU treated patients only (n = 103, p < 0.001), and is independently predictive of lack of clinical benefit from adjuvant 5FU [HR 6.25 (95%CI 1.48-26.32), p = 0.013]. CONCLUSIONS: A combined investigative model, analysing the transcriptional response in clinical tumour specimens and cancers cell lines, has identified APRIL, a novel chemo-resistance biomarker with independent predictive impact in 5FU-treated CRC patients, that may represent a target for novel therapeutics.

Gene expression analysis of human fetal ovarian primordial follicle formation.

CONTEXT: Primordial follicle formation dictates the maximal potential female reproductive capacity and establishes the ovarian reserve. Currently, little is known about this process in the human. OBJECTIVE: The aim of the study was to identify genes associated with the onset of human fetal primordial follicle formation in morphologically normal human fetuses. DESIGN: We conducted an observational study of the female fetal gonad, comparing gene expression before and during primordial follicle formation. SETTING: The study was conducted at the Universities of Aberdeen, Glasgow, and Nottingham. PATIENTS/PARTICIPANTS: Ovaries were collected from 51 morphologically normal human female fetuses of women undergoing elective termination of normal second trimester pregnancies. MAIN OUTCOME MEASURES: We performed fetal ovarian transcript expression by Affymetrix array and quantitative RT-PCR and gene product expression and localization by Western blot and immunohistochemistry. RESULTS: Five transcripts were down-regulated and 61 were up-regulated in ovaries from older fetuses (18-20 wk) in which primordial follicle formation had started compared with younger (15-16 wk) fetuses in which no primordial follicles were observed. The altered genes contribute to major functions, including gene expression, tissue morphology, and apoptosis, that are essential for ovarian development. NALP5, the most highly regulated transcript, is an oocyte-specific maternal effect gene that is regulated downstream of FIGLA. CONCLUSIONS: NALP5 probably plays a key role in the onset of human primordial follicle formation and thus the establishment of ovarian reserve in women.

Cell cycle perturbation and acquired 5-fluorouracil chemoresistance.

Acquired chemoresistance is one of the obstacles for success of 5-fluorouracil (5-FU)-based cancer chemotherapy. Some molecular mechanisms of acquired 5-FU resistance are still unknown. We have recently demonstrated down-regulation of a group of cell cycle related genes in acquired 5-FU resistant human cancer cell lines. In this study, the bivariate distribution of propidium iodide versus BrdU in acquired 5-FU resistant colon (H630R10) and breast (T47DFU2.5) cancer cell lines was compared with their parental cell lines using flow cytometric analysis. The resistant cell lines showed significantly lower labelling index (T47DFU2.5) and cell cycle delay in G1 and G1/S boundary and prolonged DNA synthesis time (H630R10). Both resistant cell lines demonstrated significantly prolonged potential doubling time (Tpot). The protein expression levels of some G1 and S phase transition-related genes were also analysed by Western blot. CDK2 protein and Thr-160 phosphorylated CDK2 were remarkably reduced in the resistant cell lines. Cyclin D3 and cyclin A were also decreased in the resistant cells. Total pRB expression was unaltered but hypophosphorylation of pRB (Ser780, Ser795 and Ser807/811) was detected in the resistant cancer cells. Our data suggest that there may be a slow down in cell cycle traverse preventing incorporation of 5-FU metabolites into DNA and also providing cancer cells with sufficient time to correct the mis-incorporated nucleotides. The cell cycle perturbation may be involved in acquired 5-FU resistance.

Decreased [18F]fluoro-2-deoxy-d-glucose incorporation and increased glucose transport are associated with resistance to 5FU in MCF7 cells in vitro.

INTRODUCTION: Tumor refractoriness to chemotherapy is frequently due to the acquisition of resistance. Resistant cells selected by exposure to chemotherapy agents may exhibit differences in [18F]fluoro-2-deoxy-d-glucose (FDG) incorporation, as compared with sensitive cells. METHODS: FDG incorporation, hexokinase (HK) activity, glucose transport and ATP content were determined in clones of 5-fluorouracil (5FU)-resistant MCF7 cells, established by long-term exposure to increasing 5FU concentrations, and in parental MCF7 cells. RESULTS: FDG incorporation was decreased in MCF7 cells resistant to 5FU; HK activity was similar in the resistant and sensitive cells, while glucose transport was increased, as compared with sensitive cells. Treatment of cells with the glucose efflux inhibitor phloretin increased FDG incorporation to similar levels in the resistant and sensitive cells. Analysis of microarray data demonstrated the expression of GLUT1, 8 and 10 transporters in MCF7 cells. GLUT8 and 10 expression was decreased in the resistant cells, while GLUT1 was only increased in cells resistant to the lowest 5FU concentration. CONCLUSION: FDG incorporation in 5FU-resistant MCF7 cells is decreased, as compared with sensitive cells. Our findings also suggest that this may be due to high rates of membrane glucose transport in the resistant cells resulting in enhanced efflux of FDG. We believe that this is the first demonstration that facilitative glucose transporters can actually decrease the incorporation of FDG.

Mechanisms of acquired chemoresistance to 5-fluorouracil and tomudex: thymidylate synthase dependent and independent networks.

PURPOSE: Thymidylate synthase (TS) over-expression is widely accepted as a major molecular mechanism responsible for 5-fluorouracil (5-FU) and tomudex (TDX) resistance. In this study, the importance of TS in 5-FU and TDX resistance was evaluated. METHODS: The sensitivity of TS-over-expressing 5-FU (3) and TDX (3) resistant cell lines to 5-FU and TDX was analysed. The cross-resistance between 5-FU and TDX resistant cell lines was determined. The relationship between p53 and NF-kappaB status and the sensitivity to 5-FU and TDX was evaluated. RESULTS: Compared to relevant parental sensitive cell lines, the 5-FU resistant cell lines were highly cross-resistant to TDX (over 20,000-fold). In contrast, over-expression of TS did not significantly confer 5-FU resistance on the TDX resistant cell lines (0.8- to 1.3-fold). Thymidine (20 microM) rescue induced TDX resistance in TDX sensitive cell lines (over 10,000-fold) but only moderately influenced 5-FU sensitivity in 5-FU sensitive cell lines (1.1- to 2.4-fold). Uridine moderately protected one cancer cell line (RKO) from 5-FU-induced, but not TDX-induced, cytotoxicity. NF-kappaB transfected MCF-7 and p53 knockout HCT116 cells were resistant to 5-FU (4.4- and 2.4-fold, respectively) but not to TDX. TS protein expression in NF-kappaB transfected and p53 knockout cell lines was comparable to the relevant parental cell lines. CONCLUSION: In some cancer cell lines, TS-independent molecular events may play a key role in 5-FU resistance. Loss of p53 function and NF-kappaB over-expression may be involved in TS-independent 5-FU chemoresistance in some cancer cell lines.

Pregnane X receptor activators inhibit human hepatic stellate cell transdifferentiation in vitro.

BACKGROUND & AIMS: The activated pregnane X receptor is antifibrogenic in rodent chronic liver injury in vivo models. The aim of this study was to determine the effects of human pregnane X receptor activators on human hepatic stellate cell transdifferentiation to a profibrogenic phenotype in vitro. METHODS: Hepatic stellate cells were isolated from resected human liver and cultured under conditions in which they trans-differentiate into profibrogenic myofibroblasts. RESULTS: The pregnane X receptor was expressed in primary cultures at the level of messenger RNA and protein and was activated by the ligand rifampicin as judged by increases in binding of proteins to the pregnane X receptor ER6 DNA response element and by increases in ER6-dependent reporter gene expression. Short-term treatment of hepatic stellate cells with rifampicin inhibited the expression of selected fibrosis-related genes (transforming growth factor beta1, alpha-smooth muscle actin), proliferation-related genes, and WNT signaling-associated genes. There was also an increase in interleukin-6 secretion and an inhibition in DNA synthesis. Long-term treatment with rifampicin over several weeks reduced the proliferation and transdifferentiation of hepatic stellate cells. Small interfering RNA knockdown of the pregnane X receptor in a hepatic stellate cell line reduced the binding of proteins to the ER6 DNA response element and abrogated pregnane X receptor activator-dependent changes in transforming growth factor beta1 expression, interleukin-6 secretion, and proliferation. CONCLUSIONS: The pregnane X receptor is transcriptionally functional in human hepatic stellate cells and activators inhibit transdifferentiation and proliferation. The pregnane X receptor may therefore be an effective target for antifibrotic therapy.

Tumor transcriptome reveals the predictive and prognostic impact of lysosomal protease inhibitors in non-small-cell lung cancer.

PURPOSE: Insight into clinical response to platinum-based chemotherapy (PBC) in non-small-cell lung cancer (NSCLC). METHODS: Matched tumor and nontumor lung tissues from PBC-treated NSCLC patients (four nonresponders and four responders) and tumor tissue from an independent test set (four nonresponders and four responders), were profiled using microarrays. Lysosomal protease inhibitors SerpinB3 and cystatin C were highly correlated with clinical response and were further evaluated by immunohistochemistry in PBC-treated patients (36 prechemotherapy and 13 postchemotherapy). Investigation of the pathogenic and prognostic significance of SerpinB3 was performed in 251 primary tumors, with 64 regional lymph node pairs, from chemotherapy-naïve NSCLC patients using immunohistochemistry. RESULTS: Bioinformatic analyses of gene expression in the training set identified a gene set (n = 17) that separated all patients in the training and test sets (n = 16) according to response in hierarchical clustering. Transcriptome profiling revealed that SerpinB3 mRNA was highly correlated with degree of response (r = -0.978; P < .0001) and was a clear outlier (nonresponders:responders > 50-fold). SerpinB3 protein expression was correlated with clinical response in PBC-treated NSCLC patients (P = .045). Expression of SerpinB3 and cystatin C, relative to the target, protease cathepsin B, was independently predictive of response (odds ratio, 17.8; 95% CI, 2.0 to 162.4; P = .01), with an accuracy of 72%. High SerpinB3 expression levels, invariably associated with chemoresistance, had contrasting prognostic impact in untreated squamous cell carcinomas (hazard ratio [HR], 0.43; 95% CI, 0.18 to 0.93) or adenocarcinomas (HR, 2.09; 95% CI, 1.03 to 4.72). CONCLUSION: This provides the first comprehensive molecular characterization of clinical responsiveness to PBC in NSCLC and reveals the predictive and prognostic impact of two lysosomal protease inhibitors, potentially representing novel targets for NSCLC therapeutics.

Mechanistic and predictive profiling of 5-Fluorouracil resistance in human cancer cells.

Gene expression was analyzed in five pairs of 5-fluorouracil (5-FU) resistant and parental cancer cell lines on DNA microarrays. In unsupervised analysis, a prediction rule was built from the expression profiles of 29 genes, and 5-FU sensitivity class was predicted with 100% accuracy and high predictive strength. In supervised analysis of key 5-FU pathways, expression of 91 genes was associated with 5-FU sensitivity phenotype and segregated samples accordingly in hierarchical analysis. Key genes involved in 5-FU activation were significantly down-regulated (thymidine kinase, 2.9-fold; orotate phosphoribosyltransferase, 2.3-fold; uridine monophosphate kinase, 3.2-fold; pyrimidine nucleoside phosphorylase 3.6-fold) in resistant cells. Overexpression of thymidylate synthase and its adjacent gene, c-Yes, was detected in the resistant cell lines. The mRNA and protein overexpression of nuclear factor kappaB (NFkappaB) p65 and related antiapoptotic c-Flip gene was detected in resistant cells. The 5-FU-resistant cell lines also showed high NFkappaB DNA-binding activity. Cotransfection of NFkappaB p50 and p65 cDNA induced 5-FU resistance in MCF-7 cells. Both NFkappaB- and 5-FU-induced resistant cell lines manifested reduced expression of genes governing G(1)-S and S-phase transition. Expression of genes involved in DNA replication was also down-regulated in resistant cell lines. These findings were highly consistent with the slower growth rate, higher proportion of G(1), and lower proportion of S-phase cells in the resistant cell lines. This phenotype may protect resistant cells from cell death induced by incorporation of 5-FU into DNA chains, by allowing time to repair 5-FU-induced damage. Our findings may provide novel targets for tackling 5-FU resistance.