Demodex-associated Bacillus proteins induce an aberrant wound healing response in a corneal epithelial cell line: possible implications for corneal ulcer formation in ocular rosacea

PURPOSE

The aim of the work presented here was to establish the response of a corneal epithelial cell line (hTCEpi) to protein extracted from a bacterium (Bacillus oleronius) previously isolated from a Demodex mite from a rosacea patient.

METHODS

The response of the corneal epithelial cell line to Bacillus proteins was measured in terms of alterations in cell migration and invasiveness. Changes in the expression of metalloproteinase genes and proteins were also assessed.

RESULTS

The results indicated increased cell migration (14.5-fold, P = 0.001) as measured using 8-μm PET inserts (BD Falcon) in a transwell assay and invasiveness (1.7-fold, P = 0.003) as measured using 8-μm Matrigel (BD Biocoat) invasion inserts in a 24-well plate assay format, following exposure to the Bacillus proteins. Cells exposed to the Bacillus protein showed a dose-dependent increase in expression of genes coding for matrix metalloprotease (MMP)-3 (61-fold) and MPP-9 (301-fold). This dose-dependent increase in gene expression was also reflected in elevated levels of MMP-9 protein (1.34-fold, P = 0.033) and increased matrix metalloprotease activity (1.96-fold, P = 0.043) being present in the culture supernatant. Cells also displayed reduced levels of β-integrin (1.25-fold, P = 0.01), indicative of increased motility and elevated levels of vinculin (2.7-fold, P = 0.0009), suggesting altered motility.

CONCLUSIONS

The results indicate that exposure of corneal epithelial cells to Bacillus proteins results in an aberrant wound healing response as visualized using a scratch wound assay. These results suggest a possible link between the high density of Demodex mites on the eyelashes of ocular rosacea patients and the development of corneal ulcers.

Pharmacological interactions of TKIs with the P-gp drug transport protein

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Background: Tyrosine Kinase Inhibitors (TKIs) can interact with drug transport proteins. P-gp is a transporter with two important roles in cancer drug therapy. If overexpressed in tumour cells it can cause drug resistance. However, P-gp, expressed in tissues as part of normal drug clearance mechanisms, is also involved in termination of drug action. Hence, TKI-mediated interactions with P-gp have significant therapeutic consequences. Methods: P-gp over-expressing cancer cell lines were used to determine the inhibitor or substrate status of tyrosine kinase inhibitors (erlotinib, gefitinib, lapatinib, dasatinb, neratinib, afatinib and pazopanib). Cell proliferation assays in combination with a potent P-gp inhibitor, or P-gp substrate were also employed. Findings were augmented using LC-MS-based quantitation of cellular levels of target drugs. Results: We summarise our findings of four distinct interactions with P-gp among various TKIs. Some agents have little interaction at conventional doses; others can act as P-gp inhibitors without being substrates; substrates without being inhibitors or substrates which also prevent the actions of the transporter.Eachof the investigated TKIs has a distinct relationship with P-gp. As examples, lapatinib is an inhibitor but not a substrate, dasatinib is a substrate but not an inhibitor, while pazopanib has little interaction with P-gp. Other agents also have an effect on or are affected by P-gp to varying amounts with some of these interactions likely to be suprapharmacological. Conclusions: P-gp protein has important roles both in resistance and drug toxicology, hence, a clear understanding of the interaction of emerging drugs with this transporter is vital. Agents which are inhibitors of P-gp may have applications in drug resistance circumvention but may also greatly exacerbate the toxicity of concurrently administered P-gp substrate cytotoxics; conversely the activity of P-gp substrate TKIs may be reduced by tumour overexpression of the transporter. Hence in vitro screening of TKI-transporter interactions may identify putative TKI resistance mechanisms, help guide the development of combination schedule trials and/or reducing unwanted treatment side effects.

Prostate cancer inhibitory activity of a novel dual inhibitor, EL102, in combination with docetaxel, and its effects on MDR1-mediated drug resistance in vitro

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Background: EL102 is a dual-action drug promoting apoptosis and inhibiting angiogenesis. It exerts its action though the inhibition of Hif1a induced hypoxic signalling and induction of the Caspase 3/7 apoptotic cascade. The drug has equal activity in normoxia and hypoxia indicating it may be equally active in these different tumor compartments. We tested its ability to circumvent chemotherapeutic drug resistance. Methods: We assessed the ability of EL102 to inhibit prostate cancer cell proliferation and motility in vitro, calculating IC50s for CWR22, 22Rv2, PC3 and DU145 prostate cancer cell lines, comparing sensitivity between androgen dependent, androgen independent and metastatic prostate cancer. Additionally we assessed the activity of EL102 in combination with docetaxel in vitro and in murine CWR22 xenografts. The ability to overcome MDR1 and BCRP mediated drug resistance was also tested using DLKP drug resistant variants which exhibit 200 fold resistance to doxorubicin, docetaxel, paclitaxel and vincristine. Results: We found that prostate cancer cell lines are sensitive to EL102 with IC50s in the region of 10-50nM. Of particular interest was the identical sensitivity of the androgen independent 22Rv1 and its androgen dependent parent CWR22, suggesting ability to overcome hormone refractory prostate cancer. Additionally we demonstrate dose response for inhibition of cell motility in metastatic DU145. In CWR22 murine mouse models treatment with EL102 resulted in decreased tumor volume compared to control. A docetaxel and EL102 combination arm demonstrated the greater inhibition of tumor growth than EL102 or docetaxel alone. The lung cancer cell line DLKP, its drug resistant variants DLKPA (MDR1 overexpressing) and DLKPMitox (BCRP overexpressing) were equally sensitive to EL102 indicating that EL102 is not a substrate for MDR1 or BCRP. Conclusions: EL102 is a potential therapeutic for the treatment of prostate cancer, in particular in combination with docetaxel, and exhbibits the potential to overcome drug resistane. Future studies will include the efficacy of this drug in prostate cancer metastatic mouse models.

Abstract 4152: Proteomic analysis identifies RAB1A as a novel marker of invasion in neuroblastoma

Neuroblastoma is a paediatric cancer arising from precursor cells of the sympathetic nervous system. Extreme heterogeneity in clinical behavior may be attributed to recurrent genomic abnormalities including chromosomal losses/gains, and amplification of the MYCN oncogene. We previously described a signature of 37 miRNAs significantly differentially expressed in MYCN amplified tumours, and have confirmed one such microRNA, miR-542-5p, acts as a tumour suppressor in neuroblastoma. Our current research focuses on identifying the mechanism of action of miR-542-5p. No enrichment for miR-542-5p 3′UTR target sites was found in a panel of mRNA differentially expressed after ectopic over-expression of miR-542-5p. We therefore hypothesize that miR-542-5p has a more significant impact on protein levels through translational inhibition than mRNA degradation. To test our hypothesis, we carried out proteomic analysis using label-free quantification of high sensitive reversed-phase liquid chromatography coupled nanospray tandem mass spectrometry (LC-MS/MS). In total, 27,000 peptides were examined per sample. Of these, 17 proteins changed significantly in MYCN amplified Kelly cells (6 down-regulated and 11 up-regulated) and 14 proteins changed significantly in MYCN single copy SKNAS cells (9 down-regulated and 5 up-regulated). No overlap between significantly differentially expressed mRNA and protein was observed, and none of the proteins identified contained miR-542-5p predicted target sites. Significance was determined based on a confidence score of greater than 40 (applies to protein identification), number of peptides used to identify and quantitate the proteins as ≤ 2, and a p-value < 0.05. Fold changes are based on difference in average protein abundance between the miR-542-5p mimic and negative control cells across 3 biological repeats. The R2 database (http://r2.amc.nl)) was used to assess the clinical relevance of these proteins. Of the 31 differentially expressed proteins, 26% were significantly associated (p < 0.05) with overall (OS), or event-free survival (EFS) in neuroblastoma. Of particular interest was RAB1A, which increased in abundance in both miR-542-5p over-expressing cell lines. Increased expression of RAB1A was associated with better OS (p=0.015) and EFS (p=0.00016), consistent with results for miR-542-5p. Depletion of cellular RAB1A mRNA by siRNA also produced similar result to that seen with miR-542-5p antagomer. In both SKNAS and Kelly cells, RAB1A knock-down resulted in a significant (p<0.001) increase in the number on invading cells, but no change in the rate of proliferation. We therefore conclude that RAB1A is indirectly regulated by miR-542-5p through a yet unknown mechanism. Reduced expression of RAB1A significantly increases in vitro invasion, consistent with clinical data showing that lower expression is highly associated with poor survival in neuroblastoma.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4152. doi:1538-7445.AM2012-4152

Impact of miR-7 over-expression on the proteome of Chinese hamster ovary cells

MicroRNAs play critical roles in the regulation of biological processes such as growth, apoptosis, productivity and secretion thus representing a potential route toward enhancing desirable characteristics of mammalian cells for biopharmaceutical production. We have previously found that miR-7 over-expression significantly inhibits the growth of CHO-SEAP cells without impacting cellular viability, with an associated increase in normalised productivity. Understanding the biological basis of this effect might open the way to new strategies for bioprocess-relevant growth regulation. In this study we have carried out a quantitative label-free LC-MS profiling study of proteins exhibiting altered levels following over-expression of miR-7 to gain insights into potential mechanisms involved in the observed phenotype. From the analysis we found 93 proteins showing decreased levels and 74 proteins with increased levels following over-expression of miR-7. Pathway analysis suggests that proteins involved in protein translation (e.g. ribosomal proteins), RNA and DNA processing (including histones) are enriched in the list of proteins showing decreased expression. Proteins involved in protein folding and secretion were found to be up-regulated following miR-7 over-expression. In silico bioinformatic analysis using miRWalk, which combined the output from 6 selected miRNA target prediction algorithms, was used to evaluate if any of the down-regulated proteins were potential direct targets of miR-7. Two genes, stathmin and catalase, which both have known roles in the regulation of cellular growth, were found to overlap a number of the predictive target database searches in both mouse and rat, and are likely to be possible direct targets of miR-7 in CHO cells. This is the first report investigating the impact of a miRNA on the proteome of CHO cells.

Utilization and evaluation of CHO-specific sequence databases for mass spectrometry based proteomics

Recently released sequence information on Chinese hamster ovary (CHO) cells promises to not only facilitate our understanding of these industrially important cell factories through direct analysis of the sequence, but also to enhance existing methodologies and allow new tools to be developed. In this article we demonstrate the utilization of CHO specific sequence information to improve mass spectrometry (MS) based proteomic identification. The use of various CHO specific databases enabled the identification of 282 additional proteins, thus increasing the total number of identified proteins by 40-50%, depending on the sample source and methods used. In addition, a considerable portion of those proteins that were identified previously based on inter-species sequence homology were now identified by a larger number of peptides matched, thus increasing the confidence of identification. The new sequence information offers improved interpretation of proteomic analyses and will, in the years to come, prove vital to unraveling the CHO proteome.

Abstract B18: EL102: A novel dual inhibitor which demonstrates additive prostate cancer inhibitory activity in combination with docetaxel in vitro and in mouse models

Introduction: EL102, a novel toluidine sulphonamide, was developed from a phenotypic screen to develop novel small molecule inhibitors of the hypoxia signalling cascade. It is a dual-inhibitor of apoptosis and angiogenesis, and exerts its action though the inhibition of Hif1 alpha induced hypoxic signalling pathways and induction of the Caspase 3/7 apoptotic cascade. The drug has equal activity against normoxic and hypoxic tumour cells indicating that it may be equally active in these different tumour compartments.

Hypothesis: We hypothesize that the dual inhibition of anti-apoptotic and angiogenic pathway is a viable therapeutic strategy for the treatment of prostate cancer, and may be additive to taxane-based chemotherapeutic strategies.

Experimental Procedures: We assessed the ability of EL102 to inhibit prostate cancer cell proliferation and cell motility in vitro in normal prostate RWPE1, androgen dependent CRW22 and its androgen independent variant 22Rv2,and the metastatic prostate cancer cell lines PC3 and DU145. Mechanistic studies included the effects of EL102 on VEGF, IL-6 and Il-8 secretion and ability to inhibit Hif1a expression. Additionally we assessed the activity of EL102 in combination with docetaxel in vitro and in murine models using CRW22 xenografts.

Results: Prostate cancer cell lines are sensitive to EL102 with IC50s for inhibition of cell proliferation in the region of 10-50nM. Of particular interest was the comparable sensitivity of the androgen independent 22Rv1 cell line and it androgen dependent parent cell line CRW22, suggesting that EL102 may also be active in hormone refractory prostate cancer. Additionally we demonstrate dose response for the inhibition of cell motility in the metastatic prostate cancer cell lines DU145. In CRW22 murine mouse models treatment with EL102 resulted in significantly decreased tumour volume compared to control. A docetaxel and EL102 combination arm demonstrated the greater inhibition of tumour growth than EL102 or docetaxel alone.

Conclusions: EL102 is a potential therapeutic agent for the treatment of prostate cancer, as a single agent or in combination with docetaxel. The histopathology of tumours from mice treated with EL102 in combination with docetaxel on Ki-67, Hif1 alpha, VEGF and apoptosis in vivo is evaluated. Future studies will establish the efficacy of EL102 in a PC3 metastatic prostate cancer mouse model. Additionally the ability of EL102 to circumvent the classic drug resistance mechanisms MDR1, MRP1 and BCRP, and overcome taxane resistance will be presented.

Citation Format: Aidan Toner, Fiona McLaughlin, Jill McMahon, Francis J. Giles, Frank Sullivan, Laura Breen, Martin Clynes, Joe D. Lewis, Sharon A. Glynn. EL102: A novel dual inhibitor which demonstrates additive prostate cancer inhibitory activity in combination with docetaxel in vitro and in mouse models [abstract]. In: Proceedings of the AACR Special Conference on Advances in Prostate Cancer Research; 2012 Feb 6-9; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2012;72(4 Suppl):Abstract nr B18.

Characterization and response of newly developed high-grade glioma cultures to the tyrosine kinase inhibitors, erlotinib, gefitinib and imatinib

High-grade gliomas (HGG), are the most common aggressive brain tumours in adults. Inhibitors targeting growth factor signalling pathways in glioma have shown a low clinical response rate. To accurately evaluate response to targeted therapies further in vitro studies are necessary. Growth factor pathway expression using epidermal growth factor receptor (EGFR), mutant EGFR (EGFRvIII), platelet derived growth factor receptor (PDGFR), C-Kit and C-Abl together with phosphatase and tensin homolog (PTEN) expression and downstream activation of AKT and phosphorylated ribosomal protein S6 (P70S6K) was analysed in 26 primary glioma cultures treated with the tyrosine kinase inhibitors (TKIs) erlotinib, gefitinib and imatinib. Response to TKIs was assessed using 50% inhibitory concentrations (IC(50)). Response for each culture was compared with the EGFR/PDGFR immunocytochemical pathway profile using hierarchical cluster analysis (HCA) and principal component analysis (PCA). Erlotinib response was not strongly associated with high expression of the growth factor pathway components. PTEN expression did not correlate with response to any of the three TKIs. Increased EGFR expression was associated with gefitinib response; increased PDGFR-α expression was associated with imatinib response. The results of this in vitro study suggest gefitinib and imatinib may have therapeutic potential in HGG tumours with a corresponding growth factor receptor expression profile.

Invasive markers identified by gene expression profiling in pancreatic cancer

BACKGROUND

Molecular profiling has proven utility as a diagnostic and predictive tool in clinical oncology. However, a clinically relevant gene expression profile in pancreatic cancer remains elusive.

METHODS

Primary and metastatic pancreatic cancer cell lines (BxPC-3 and AsPC-1), were stimulated with phorbol-12-myristate 13-acetate (PMA), a known inducer of cell invasion. Affymetrix gene expression microarray analysis was performed, comparing gene expression to unstimulated controls. Differential expression was identified using ArrayAssist, and confirmed using quantitative real-time PCR. Bioinformatic analysis was performed using Pathway Studio and GOstat. The derived gene expression was further validated in fresh frozen pancreatic tumour samples. The ability of the derived 3 gene expression markersto differentiate between pancreatic adenocarcinoma (PDAC) and other neoplasms, and its association with clinicopathological variables was examined.

RESULTS

PMA-induced significant changes in cell line gene expression, from which distinctive 3 potential invasive markers were derived. Expression of these genes, uPA, MMP-1 and IL1-R1 was confirmed in human pancreatic tumours, and was found to differentiate PDAC from other pancreatic neoplasms. The expression of IL1-R1 in PDAC is a novel finding. We found that the expression of MMP-1 was associated with high-grade PDAC (p = 0.035, Wilcoxon rank sum).

CONCLUSION

We have identified three potential invasive markers, uPA, MMP-1 and IL1-R1, whose gene expression may differentiate PDAC from other pancreatic neoplasms, and potentially reflect a more invasive phenotype.

MAGE-D4B is a novel marker of poor prognosis and potential therapeutic target involved in breast cancer tumorigenesis

Melanoma-associated antigen (MAGE) family members are generally described as tumor-specific antigens. An association between MAGE-D4B and breast cancer has yet to be reported and the functional role of the encoded protein has never been established. We performed microarray analysis of 104 invasive breast tumors and matched non-cancerous breast biopsies. qPCR was used for validation in an independent biobank. To investigate the biological relevance of MAGE-D4B in breast tumorigenesis, its phenotypic effects were assessed in vitro. Overall, MAGE-D4B was detected in 43% of tumors while undetected in normal breast tissue. MAGE-D4B was found to correlate with tumor progression and to be an independent prognostic marker for poor outcome in term of relapse-free and overall survival, with potential predictive relevance in relation to response to chemotherapy. RNA interference-mediated knockdown of MAGE-D4B significantly hampered the invasive properties of Hs578T cells by affecting anchorage-independent growth, adhesion, migration and invasion affecting anchorage-independent growth, adhesion, migration and invasion and by modulating expression of invasion-suppressor gene E-cadherin.

Sustained productivity in recombinant Chinese hamster ovary (CHO) cell lines: proteome analysis of the molecular basis for a process-related phenotype

Background

The ability of mammalian cell lines to sustain cell specific productivity (Qp) over the full duration of bioprocess culture is a highly desirable phenotype, but the molecular basis for sustainable productivity has not been previously investigated in detail. In order to identify proteins that may be associated with a sustained productivity phenotype, we have conducted a proteomic profiling analysis of two matched pairs of monoclonal antibody-producing Chinese hamster ovary (CHO) cell lines that differ in their ability to sustain productivity over a 10 day fed-batch culture.

Results

Proteomic profiling of inherent differences between the two sets of comparators using 2D-DIGE (Difference Gel Electrophoresis) and LC-MS/MS resulted in the identification of 89 distinct differentially expressed proteins. Overlap comparisons between the two sets of cell line pairs identified 12 proteins (AKRIB8, ANXA1, ANXA4, EIF3I, G6PD, HSPA8, HSP90B1, HSPD1, NUDC, PGAM1, RUVBL1 and CNN3) that were differentially expressed in the same direction.

Conclusion

These proteins may have an important role in sustaining high productivity of recombinant protein over the duration of a fed-batch bioprocess culture. It is possible that many of these proteins could be useful for future approaches to successfully manipulate or engineer CHO cells in order to sustain productivity of recombinant protein.

Characterisation of BHK-21 cells engineered to secrete human insulin

Autoimmune destruction of beta cells in the pancreas leads to type I, or insulin dependent diabetes mellitus (IDDM), through the loss of endogenous insulin production capacity. This paper describes an attempt to generate 'artificial'beta cells using the fibroblast cell line BHK21. Stable transfectants expressing the human preproinsulin (PPI) gene were isolated and characterised. The resulting clone selected for further analysis (BHK-PPI-C16) was capable of secreting 0.12 pmol proinsulin/hr/10(5) cells and maintained a steady cellular proinsulin content of 0.36 +/- 0.04 pmol l(-1). There was no processing of the proinsulin to mature insulin. The cells were unresponsive to glucose but there was increased proinsulin secretion in the presence of agents that stimulated formation of intracellular cAMP. Transfection of cDNAs for the key elements of the glucose sensing apparatus (GLUT2 and glucokinase) led to a subphysiological stimulation of secretion when glucokinase was transfected alone while there was a complete loss of insulin secretion when both components were overexpressed. The deleterious effect on proinsulin secretion observed upon co-expression of the glucose sensing genes may have implications for applications requiring multigene expression in BHK21 cells.

Challenges of drug resistance in the management of pancreatic cancer

The current treatment of choice for metastatic pancreatic cancer involves single-agent gemcitabine or a combination of gemcitabine with capecitabine or erlotinib (a tyrosine kinase inhibitor). Only 25–30% of patients respond to this treatment and patients who do respond initially ultimately exhibit disease progression. Median survival for pancreatic cancer patients has reached a plateau due to inherent and acquired resistance to these agents. Key molecular factors implicated in this resistance include: deficiencies in drug uptake, alteration of drug targets, activation of DNA repair pathways, resistance to apoptosis and the contribution of the tumor microenvironment. Moreover, for newer agents including tyrosine kinase inhibitors, overexpression of signaling proteins, mutations in kinase domains, activation of alternative pathways, mutations of genes downstream of the target and/or amplification of the target represent key challenges for treatment efficacy. Here we will review the contribution of known mechanisms and markers of resistance to key pancreatic cancer drug treatments.

RNAi knockdown of Hop (Hsp70/Hsp90 organising protein) decreases invasion via MMP-2 down regulation

We previously identified Hop as over expressed in invasive pancreatic cancer cell lines and malignant tissues of pancreatic cancer patients, suggesting an important role for Hop in the biology of invasive pancreatic cancer. Hop is a co-chaperone protein that binds to both Hsp70/Hsp90. We hypothesised that by targeting Hop, signalling pathways modulating invasion and client protein stabilisation involving Hsp90-dependent complexes may be altered. In this study, we show that Hop knockdown by small interfering (si)RNA reduces the invasion of pancreatic cancer cells, resulting in decreased expression of the downstream target gene, matrix metalloproteinases-2 (MMP-2). Hop in conditioned media co-immunoprecipitates with MMP-2, implicating a possible extracellular function for Hop. Knockdown of Hop expression also reduced expression levels of Hsp90 client proteins, HER2, Bcr-Abl, c-MET and v-Src. Furthermore, Hop is strongly expressed in high grade PanINs compared to lower PanIN grades, displaying differential localisation in invasive ductal pancreatic cancer, indicating that the localisation of Hop is an important factor in pancreatic tumours. Our data suggests that the attenuation of Hop expression inactivates key signal transduction proteins which may decrease the invasiveness of pancreatic cancer cells possibly through the modulation of Hsp90 activity. Therefore, targeting Hop in pancreatic cancer may constitute a viable strategy for targeted cancer therapy.

A novel panel of protein biomarkers for predicting response to thalidomide-based therapy in newly diagnosed multiple myeloma patients

Multiple myeloma (MM) is a heterogeneous group of disorders both genotypically and phenotypically. Response to thalidomide-based induction therapy in newly diagnosed patients varies significantly in published clinical trials. Proteomic analysis was performed on 39 newly diagnosed MM patients treated with a thalidomide-based regimen (22 responders; 17 non-responders) using immunodepletion, 2-D DIGE analysis and mass spectrometry. Zinc-α-2-glycoprotein (ZAG), vitamin D-binding protein (VDB), serum amyloid-A protein (SAA) and β-2-microglobulin (B2M) had statistically significant higher concentrations in non-responders compared to responders, while haptoglobin (Hp) had a lower concentration. ELISAs were used to validate the candidate protein biomarkers using unfractionated serum from 51 newly diagnosed MM patients (29 responders; 22 non-responders). Using logistic regression, the best possible area under the curve (AUC) was 0.96 using ZAG, VDB and SAA in combination. Leave-one-out-cross-validation (LOOCV) indicated an overall predictive accuracy of 84% with associated sensitivity and specificity values of 81.8 and 86.2%, respectively. Subsequently, 16 of 22 thalidomide-refractory patients successfully achieved complete response or very good partial response using second-line treatment suggesting that the biomarker profile is specific to thalidomide response rather than identifying patients with MM refractory to all therapies. Using a novel panel of predictive biomarkers, the feasibility of predicting response to thalidomide-based therapy in previously untreated MM has been demonstrated.