Interleukin-8 and its receptor CXCR2 in the tumour microenvironment promote colon cancer growth, progression and metastasis

BACKGROUND: Colorectal cancer (CRC) is a leading cause of death in the United States. Increased level of interleukin-8 (IL-8) and CXCR2 on tumours and in the tumour microenvironment has been associated with CRC growth, progression and recurrence in patients. Here, we aimed to evaluate the effects of tissue microenvironment-encoded IL-8 and CXCR2 on colon cancer progression and metastasis.

METHODS: A novel immunodeficient, skin-specific IL-8-expressing transgenic model was generated to evaluate colon cancer growth and metastasis. Syngeneic mouse colon cancer cells were grafted in CXCR2 knockout (KO) mice to study the contribution of CXCR2 in the microenvironment to cancer growth.

RESULTS: Elevated levels of IL-8 in the serum and tumour microenvironment profoundly enhanced the growth of human and mouse colon cancer cells with increased peri-tumoural angiogenesis, and also promoted the extravasation of the cancer cells into the lung and liver. The tumour growth was inhibited in CXCR2 KO mice with significantly reduced tumour angiogenesis and increased tumour necrosis.

CONCLUSION: Increased expression of IL-8 in the tumour microenvironment enhanced colon cancer growth and metastasis. Moreover, the absence of its receptor CXCR2 in the tumour microenvironment prevented colon cancer cell growth. Together, our study demonstrates the critical roles of the tumour microenvironment-encoded IL-8/CXCR2 in colon cancer pathogenesis, validating the pathway as an important therapeutic target.

A novel fluorescence-based assay for the rapid detection and quantification of cellular deoxyribonucleoside triphosphates

Current methods for measuring deoxyribonucleoside triphosphates (dNTPs) employ reagent and labor-intensive assays utilizing radioisotopes in DNA polymerase-based assays and/or chromatography-based approaches. We have developed a rapid and sensitive 96-well fluorescence-based assay to quantify cellular dNTPs utilizing a standard real-time PCR thermocycler. This assay relies on the principle that incorporation of a limiting dNTP is required for primer-extension and Taq polymerase-mediated 5-3' exonuclease hydrolysis of a dual-quenched fluorophore-labeled probe resulting in fluorescence. The concentration of limiting dNTP is directly proportional to the fluorescence generated. The assay demonstrated excellent linearity (R(2) > 0.99) and can be modified to detect between ∼0.5 and 100 pmol of dNTP. The limits of detection (LOD) and quantification (LOQ) for all dNTPs were defined as <0.77 and <1.3 pmol, respectively. The intra-assay and inter-assay variation coefficients were determined to be <4.6% and <10%, respectively with an accuracy of 100 ± 15% for all dNTPs. The assay quantified intracellular dNTPs with similar results obtained from a validated LC-MS/MS approach and successfully measured quantitative differences in dNTP pools in human cancer cells treated with inhibitors of thymidylate metabolism. This assay has important application in research that investigates the influence of pathological conditions or pharmacological agents on dNTP biosynthesis and regulation.

Histone deacetylase inhibitors suppress thymidylate synthase gene expression and synergize with the fluoropyrimidines in colon cancer cells

Despite recent therapeutic advances, the response rates to chemotherapy for patients with metastatic colon cancer remain at approximately 50% with the fluoropyrimidine, 5-fluorouracil (5-FU), continuing to serve as the foundation chemotherapeutic agent for the treatment of this disease. Previous studies have demonstrated that overexpression of thymidylate synthase (TS) is a key determinant of resistance to 5-FU-based chemotherapy. Therefore, there is a significant need to develop alternative therapeutic strategies to overcome TS-mediated resistance. In this study, we demonstrate that the histone deacetylase inhibitors (HDACi) vorinostat and LBH589 significantly downregulate TS gene expression in a panel of colon cancer cell lines. Downregulation of TS was independent of p53, p21 and HDAC2 expression and was achievable in vivo as demonstrated by mouse xenograft models. We provide evidence that HDACi treatment leads to a potent transcriptional repression of the TS gene. Combination of the fluoropyrimidines 5-FU or FUdR with both vorinostat and LBH589 enhanced cell cycle arrest and growth inhibition. Importantly, the downstream effects of TS inhibition were significantly enhanced by this combination including the inhibition of acute TS induction and the enhanced accumulation of the cytotoxic nucleotide intermediate dUTP. These data demonstrate that HDACi repress TS expression at the level of transcription and provides the first evidence suggesting a direct mechanistic link between TS downregulation and the synergistic interaction observed between HDACi and 5-FU. This study provides rationale for the continued clinical evaluation of HDACi in combination with 5-FU-based therapies as a strategy to overcome TS-mediated resistance.

Interleukin-8 is associated with proliferation, migration, angiogenesis and chemosensitivity in vitro and in vivo in colon cancer cell line models

Interleukin-8 (IL-8), a chemokine with a defining CXC amino acid motif, is known to possess tumorigenic and proangiogenic properties. Overexpression of IL-8 has been detected in many human tumors, including colorectal cancer (CRC), and is associated with poor prognosis. The goal of our study was to determine the role of IL-8 overexpression in CRC cells in vitro and in vivo. We stably transfected the IL-8 cDNA into two human colon cancer cell lines, HCT116 and Caco2, and selected IL-8-secreting transfectants. Real-time RT-PCR confirmed that IL-8 mRNA was overexpressed in IL-8 transfectants with 45- to 85-fold higher than parental cells. The IL-8-transfected clones secreted 19- to 28-fold more IL-8 protein than control and parental cells as detected by ELISA. The IL-8 transfectants demonstrated increased cellular proliferation, cell migration and invasion based on functional assays. Growth inhibition studies showed that IL-8 overexpression lead to a significant resistance to oxaliplatin (p < 0.0001). Inhibition of IL-8 overexpression with small interfering RNA reversed the observed increases in tumorigenic functions and oxaliplatin resistance, suggesting that IL-8 not only provides a proliferative advantage but also promotes the metastatic potential of colon cancer cells. Using a tumor xenograft model, IL-8-expressing cells formed significantly larger tumors than the control cells with increased microvessel density. Together, these findings indicate that overexpression of IL-8 promotes tumor growth, metastasis, chemoresistance and angiogenesis, implying IL-8 to be an important therapeutic target in CRC.

Gender-specific genomic profiling in metastatic colorectal cancer patients treated with 5-fluorouracil and oxaliplatin

AIMS: Survival and response rates in metastatic colorectal cancer remain poor, despite advances in drug development. There is increasing evidence to suggest that gender-specific differences may contribute to poor clinical outcome. We tested the hypothesis that genomic profiling of metastatic colorectal cancer is dependent on gender.

MATERIALS & METHODS: A total of 152 patients with metastatic colorectal cancer who were treated with oxaliplatin and continuous infusion 5-fluorouracil were genotyped for 21 polymorphisms in 13 cancer-related genes by PCR. Classification and regression tree analysis tested for gender-related association of polymorphisms with overall survival, progression-free survival and tumor response.

RESULTS: Classification and regression tree analysis of all polymorphisms, age and race resulted in gender-specific predictors of overall survival, progression-free survival and tumor response. Polymorphisms in the following genes were associated with gender-specific clinical outcome: estrogen receptor β, EGF receptor, xeroderma pigmentosum group D, voltage-gated sodium channel and phospholipase A2.

CONCLUSION: Genetic profiling to predict the clinical outcome of patients with metastatic colorectal cancer may depend on gender.

Interferon-γ stimulates CD14, TLR2 and TLR4 mRNA expression in gingival fibroblasts increasing responsiveness to bacterial challenge

Objective: To investigate the potential effects of IFN-y on the responsiveness of human gingival fibroblasts to bacterial challenge.
Design :mRNA and protein expression of CD14, TLR2 and TLR4 in human gingival fibroblasts was detected by quantitative polymerase chain reaction (Q-PCR) and flow cytometry. The effect of preincubation with IFN-y on subsequent bacterial LPS-induced expression of IL-6 and IL-8 by gingival fibroblasts was determined by ELISA. Bacterial LPS-induced IκBα degradation in human gingival fibroblasts was investigated by western blot.
Results: Human gingival fibroblasts express CD14, TLR2 and TLR4 mRNAs. IFN-y, but not IL-1B, induced mRNA expression of all three receptors and the expression of membrane bound CD14 protein. Pre-incubation of fibroblasts with IFN-y and subsequent stimulation with Escherichia coli LPS or Porphyromonas gingivalis LPS led to increased production of IL-6 and IL-8. LPS-induced pro-inflammatory cytokine production was abrogated by a blocking antibody to CD14. Both E. coli LPS and P. gingivalis LPS induced IκBα degradation in human gingival fibroblasts.
Conclusion: Our data indicate that IFN-y primes human gingival fibroblasts, through the upregulation of CD14 expression, which results in increased responsiveness to bacterial LPS challenge, as determined by pro-inflammatory cytokine production.

Effects of LL-37 on Human Gingival Fibroblast Function

Background and Objectives: Gingival fibroblasts play a significant role in the innate immune response of the periodontium to bacterial stimulation. A number of microorganisms and their by-products induce a host response that commonly leads to tissue destruction and periodontal disease progression. LL-37 is an antimicrobial peptide which has multiple roles in host defence including immunomodulation and wound-healing. We have investigated the role of LL-37 on the responsiveness of human gingival fibroblasts to microbial challenge from E. coli lipopolysaccharide (LPS) and P. gingivalis LPS, as well as exploring the direct effects of LL-37 on human gingival fibroblasts. Methods: The effect of LL-37 on bacterial LPS-induced expression of IL-6 and IL-8 by gingival fibroblasts was determined by ELISA. The influence of LL-37 on bacterial LPS-induced IκBα degradation in human gingival fibroblasts was investigated by western blot. The direct effects of LL-37 on modulating gingival fibroblasts gene expression were initially determined by DNA microarray analysis and subsequently confirmed by quantitative polymerase chain reaction (Q-PCR) and ELISA analysis of 9 selected genes. Results: Bacterial LPS-induced IL-8 and IL-6 production by human gingival fibroblasts were significantly reduced in the presence of LL-37 at concentrations in the range of 1-10 µg/ml (p<0.05). The presence of LL-37 at a concentration of 5 µg/ml led to a reduction in LPS-induced IκBα degradation by E. coli LPS (100 ng/ml) and P. gingivalis LPS (10 µg/ml). LL-37 (50 µg/ml) significantly altered the gene expression of 367 genes in human gingival fibroblasts by at least 2-fold. CXCL1, CXCL2, CXCL3, IL-24, IL-8, CCL2, and SOCS3 mRNA were significantly upregulated by LL-37 (p<0.05). LL-37 also significantly stimulated expression of IL-8, hepatocyte growth factor (HGF) and CXCL1 (p<0.05) at the protein level. Discussion: LL-37 plays an important role in the innate immune response due to its broad spectrum antimicrobial and immunomodulatory activity. The ability of LL-37 to directly regulate expression of a range of genes, central to the pathogenesis of periodontitis, identifies multiple roles for the peptide in host homeostasis.

Identification of novel Factor XI mutations in a patient requiring dental extractions

Factor XI is a serine protease that participates in the intrinsic pathway of blood coagulation. Patients deficient in factor XI exhibit varying degrees of post operative bleeding following invasive surgical procedures such as dental extractions. Objectives: The aim of the study was to identify the specific mutations in a patient from a family with known factor XI deficiency. Methods: Samples were obtained from the patient, his mother and his father and subjected to DNA sequencing. Each protein coding exon 2-15 of the factor XI gene was amplified by polymerase chain reaction (PCR) followed by bidirectional sequencing utilizing di-deoxy chain termination chemistry. Results: The patient had a factor XI level of 20% of normal. Initial sequencing of factor XI from the patient identified a point mutation (646G>A) and a putative splice site mutation (1567+4A>T) in intron 13. These are novel previously unreported mutations. DNA sequence analysis of the mother revealed the 1567+4A>T mutation and the father exhibited the 646G>A mutation. As a consequence the treatment proceeded without serious bleeding complication and required administration only of transexamic acid though factor XI was available as haemostatic cover. Conclusion: The two mutations identified in this family are novel; further laboratory investigation of the functional consequences of those mutations is currently underway. Although factor XI deficiency is rare in the Northern Irish population this study highlights the techniques available to sequence and analyse this and similar haematological disorders.

The Early Effects of Rapid Androgen Deprivation on Human Prostate Cancer

The androgen receptor (AR) is the dominant growth factor in prostate cancer (PCa). Therefore, understanding how ARs regulate the human transcriptome is of paramount importance. The early effects of castration on human PCa have not previously been studied 27 patients medically castrated with degarelix 7 d before radical prostatectomy. We used mass spectrometry, immunohistochemistry, and gene expression array (validated by reverse transcription-polymerase chain reaction) to compare resected tumour with matched, controlled, untreated PCa tissue. All patients had levels of serum androgen, with reduced levels of intraprostatic androgen at prostatectomy. We observed differential expression of known androgen-regulated genes (TMPRSS2, KLK3, CAMKK2, FKBP5). We identified 749 genes downregulated and 908 genes upregulated following castration. AR regulation of α-methylacyl-CoA racemase expression and three other genes (FAM129A, RAB27A, and KIAA0101) was confirmed. Upregulation of oestrogen receptor 1 (ESR1) expression was observed in malignant epithelia and was associated with differential expression of ESR1-regulated genes and correlated with proliferation (Ki-67 expression).

PATIENT SUMMARY: This first-in-man study defines the rapid gene expression changes taking place in prostate cancer (PCa) following castration. Expression levels of the genes that the androgen receptor regulates are predictive of treatment outcome. Upregulation of oestrogen receptor 1 is a mechanism by which PCa cells may survive despite castration.

An in vitro model of nociceptors in human trigeminal nerves

Background: The oro-facial region is densely innervated by the trigeminal nerve, which when stimulated can induce noxious pain sensation and contribute to neurogenic inflammation in local tissues. Recent research on the expression of specialised ion channels on the trigeminal nerve has highlighted the need to undertake more extensive studies on ion channel expression/functionality with the aim of elucidating their role in pain sensations. A major family of such ion channels is the transient receptor potential (TRP) channels which are activated by a wide variety of thermal, mechanical or chemical stimuli and merit investigation as possible druggable targets for future analgesics.
Objective: Study of TRP channel expression and regulation in oro-facial tissues is hindered by the fact that the cell bodies of neurons innervating these tissues are located in the trigeminal ganglion. Using dental pulp stem cells differentiated towards peripheral neuronal equivalents (PNEs), we sought to determine TRP channel expression, functionality and potential modulation by cytokines in this novel model.
Method: Dental pulp stem cells (DPSCs) were grown on substrate-coated tissue culture plates and differentiated towards a neuronal phenotype using neuronal induction media. Quantitative polymerase chain reaction (qPCR) was performed on PNEs +/-cytokine treatment. Ion channel functionality was investigated using whole cell patch clamping.
Result: qPCR analysis showed that PNEs expressed the TRP channels TRPA1, TRPV1, TRPV4 and TRPM8. TRPA1 was the most abundantly expressed TRP channel studied whereas TRPM8 was lowly expressed. TRP channel expression was shown to be regulated by treatment with inflammatory cytokines. Patch clamp studies using specific agonists and antagonists for TRPA1 and TRPV1 showed these channels were functional.
Conclusion: PNEs differentiated from DPSCs provide a suitable model for TRP channel expression, regulation, and sensistisation in oro-facial tissues. This human neuronal model has potential for use in pre-clinical studies of novel analgesics.

DNA-Repair Defects and Olaparib in Metastatic Prostate Cancer

BACKGROUND: Prostate cancer is a heterogeneous disease, but current treatments are not based on molecular stratification. We hypothesized that metastatic, castration-resistant prostate cancers with DNA-repair defects would respond to poly(adenosine diphosphate [ADP]-ribose) polymerase (PARP) inhibition with olaparib.

METHODS: We conducted a phase 2 trial in which patients with metastatic, castration-resistant prostate cancer were treated with olaparib tablets at a dose of 400 mg twice a day. The primary end point was the response rate, defined either as an objective response according to Response Evaluation Criteria in Solid Tumors, version 1.1, or as a reduction of at least 50% in the prostate-specific antigen level or a confirmed reduction in the circulating tumor-cell count from 5 or more cells per 7.5 ml of blood to less than 5 cells per 7.5 ml. Targeted next-generation sequencing, exome and transcriptome analysis, and digital polymerase-chain-reaction testing were performed on samples from mandated tumor biopsies.

RESULTS: Overall, 50 patients were enrolled; all had received prior treatment with docetaxel, 49 (98%) had received abiraterone or enzalutamide, and 29 (58%) had received cabazitaxel. Sixteen of 49 patients who could be evaluated had a response (33%; 95% confidence interval, 20 to 48), with 12 patients receiving the study treatment for more than 6 months. Next-generation sequencing identified homozygous deletions, deleterious mutations, or both in DNA-repair genes--including BRCA1/2, ATM, Fanconi's anemia genes, and CHEK2--in 16 of 49 patients who could be evaluated (33%). Of these 16 patients, 14 (88%) had a response to olaparib, including all 7 patients with BRCA2 loss (4 with biallelic somatic loss, and 3 with germline mutations) and 4 of 5 with ATM aberrations. The specificity of the biomarker suite was 94%. Anemia (in 10 of the 50 patients [20%]) and fatigue (in 6 [12%]) were the most common grade 3 or 4 adverse events, findings that are consistent with previous studies of olaparib.

CONCLUSIONS: Treatment with the PARP inhibitor olaparib in patients whose prostate cancers were no longer responding to standard treatments and who had defects in DNA-repair genes led to a high response rate. (Funded by Cancer Research UK and others; ClinicalTrials.gov number, NCT01682772; Cancer Research UK number, CRUK/11/029.).

mRNA Levels of BACE1 and its interacting proteins, RTN3 and PPIL2, correlate in human post mortem brain tissue

β-Site amyloid precursor protein cleaving enzyme (BACE1) is the rate-limiting enzyme for production of Aβ peptides, proposed to drive the pathological changes found in Alzheimer’s disease (AD). Reticulon 3 (RTN3) is a negative modulator of BACE1 (β-secretase) proteolytic activity, while peptidylprolyl isomerase (cyclophilin)-like 2 (PPIL2) positively regulated BACE1 gene expression in a cell-based assay. This study aimed to analyze RTN3 and PPIL2 mRNA levels in four brain regions from individuals with AD and controls. BACE1 mRNA had been previously quantified in the samples, as had glial fibrillary acidic protein (GFAP) and neuron-specific enolase (NSE), to track changing cell populations in the tissue. mRNA levels in the human post mortem brain tissue were assayed using quantitative real-time polymerase chain reaction (qPCR) and qbasePLUS, employing validated stably expressed reference genes. No differences in RTN3 or PPIL2 mRNA levels were found in individuals with AD, compared to controls. Both RTN3 and PPIL2 mRNA levels correlated significantly with BACE1 mRNA and all three showed similar disease stage-dependent changes with respect to NSE and GFAP. These findings indicated that the in vitro data demonstrating an effect of PPIL2 on BACE1 expression have functional relevance in vivo. Further research into BACE1-interacting proteins could provide a fruitful approach to the modulation of this protease and consequently Aβ production.