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  • 1
    Keywords: APOPTOSIS ; PATHWAYS ; DEATH ; MESSENGER-RNA ; IDENTIFICATION ; chemotherapy ; PROGRESS ; Anti-cancer ; ENDOPLASMIC-RETICULUM-STRESS ; ACTIVATING TRANSCRIPTION FACTOR-3 ; Bio-weapon ; Depurination ; RICIN ; RIP ; Riproximin ; UPR ; Volkensin ; XIMENIA-AMERICANA
    Abstract: Cytotoxic ribosome-inactivating proteins (RIPs) of type II such as ricin were investigated as anti-cancer agents, but also pose a threat as biological weapons. The molecular mechanism leading to their toxic effects is, however, not yet clear. The current paradigm, which states that the irreversible depurination of 28S rRNA results in a general translational arrest eventually leading to cell death, has been questioned. Using micro-array, qRT-PCR and Western blot, we identified the unfolded protein response (UPR), a cellular mechanism activated in response to endoplasmic reticulum stress, that is induced in HCT116 and MDA-MB-231 cells exposed to the plant type II RIPs ricin, riproximin and volkensin. Apoptosis was induced by concentrations at which translation of UPR-related genes still occurred, despite concomitant ribosomal depurination. We conclude that UPR induction represents a model that better describes the cellular effects of RIP exposure at concentrations at which selected proteins are translated despite ribosomal depurination.
    Type of Publication: Journal article published
    PubMed ID: 20844919
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  • 2
    Keywords: EXPRESSION ; LUNG-CANCER ; TUMORS ; IDENTIFICATION ; leukemia ; URINARY-BLADDER ; STEM-CELLS ; PAX5 ; C-MET ; SMALL-CELL-CARCINOMA
    Abstract: Purpose: For rare cancers such as neuroendocrine bladder cancer treatment options are limited due partly to the lack of preclinical models. Techniques to amplify rare primary neuroendocrine bladder cancer cells could provide novel tools for the discovery of drug and diagnostic targets. We developed preclinical experimental models for neuroendocrine bladder cancer. Materials and Methods: Fresh tumor tissue from 2 patients with neuroendocrine bladder cancer was used to establish in vitro and in vivo models. We analyzed additional archived tissues in the National Center of Tumor Diseases tissue bank from patients with neuroendocrine bladder cancer. Primary tumor samples were collected during radical cystectomy. PHA-665752 was used to inhibit MET in animal models and cell cultures. The expression of markers and drug targets in neuroendocrine bladder cancer was determined by flow cytometry. The growth of neuroendocrine bladder cancer in vitro was determined by counting live cells. Tumor growth in mice was assessed by measuring tumor volume. Groups were compared using the nonparametric Kruskal-Wallis test. Results: Xenograft models and serum-free cultures of neuroendocrine bladder cancer cells allowed screening for cell surface markers and drug targets. We found expression of the HGF receptor MET in neuroendocrine bladder cancer cultures, xenograft models and primary patient sections. The growth of neuroendocrine bladder cancer spheroids in vitro depended critically on HGF. Treatment of neuroendocrine bladder cancer bearing mice with a MET inhibitor significantly decreased tumor growth compared to that in control treated mice. Conclusions: Neuroendocrine bladder cancer xenografts and serum-free cultures provided suitable models in which to identify diagnostic markers and therapeutic targets. Using the models, we noted HGF dependent growth of human neuroendocrine bladder cancer and identified MET as a new treatment target for neuroendocrine bladder cancer.
    Type of Publication: Journal article published
    PubMed ID: 23820058
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  • 3
    Keywords: CLONING ; PROTEIN ; SEQUENCE ; ISOFORMS ; IDENTIFICATION ; CHROMATOGRAPHY ; LECTINS ; RIBOSOME-INACTIVATING PROTEINS ; PLANTS ; Riproximin ; A-CHAIN ; Plant lectin ; RICINUS-COMMUNIS AGGLUTININ ; SAMBUCUS ; Type II RIP ; VISCUM-ALBUM L ; Ximenia americana
    Abstract: Highly pure riproximin was isolated from the fruit kernels of Ximenia americana, a defined, seasonally available and potentially unlimited herbal source. The newly established purification procedure included an initial aqueous extraction, removal of lipids with chloroform and subsequent chromatographic purification steps on a strong anion exchange resin and lactosyl-Sepharose. Consistent purity and stable biological properties were shown over several purification batches. The purified, kernel-derived riproximin was characterized in comparison to the African plant material riproximin and revealed highly similar biochemical and biological properties but differences in the electrophoresis pattern and mass spectrometry peptide profile. Our results suggest that although the purified fruit kernel riproximin consists of a mixture of closely related isoforms, it provides a reliable basis for further research and development of this type II ribosome inactivating protein (RIP).
    Type of Publication: Journal article published
    PubMed ID: 22178181
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  • 4
    Keywords: RECEPTOR ; EXPRESSION ; PROTECTION ; EMPHYSEMA ; DIFFERENTIATION ; IDENTIFICATION ; OXIDATIVE STRESS ; SULFORAPHANE ; epidermal barrier ; DIOXIN
    Abstract: The transcription factor Nrf2 is a key regulator of the cellular stress response, and pharmacological Nrf2 activation is a promising strategy for skin protection and cancer prevention. We show here that prolonged Nrf2 activation in keratinocytes causes sebaceous gland enlargement and seborrhea in mice due to upregulation of the growth factor epigen, which we identified as a novel Nrf2 target. This was accompanied by thickening and hyperkeratosis of hair follicle infundibula. These abnormalities caused dilatation of infundibula, hair loss, and cyst development upon aging. Upregulation of epigen, secretory leukocyte peptidase inhibitor (Slpi), and small proline-rich protein 2d (Sprr2d) in hair follicles was identified as the likely cause of infundibular acanthosis, hyperkeratosis, and cyst formation. These alterations were highly reminiscent to the phenotype of chloracne/"metabolizing acquired dioxin-induced skin hamartomas" (MADISH) patients. Indeed, SLPI, SPRR2, and epigen were strongly expressed in cysts of MADISH patients and upregulated by dioxin in human keratinocytes in an NRF2-dependent manner. These results identify novel Nrf2 activities in the pilosebaceous unit and point to a role of NRF2 in MADISH pathogenesis.
    Type of Publication: Journal article published
    PubMed ID: 24503019
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  • 5
    Keywords: carcinoma ; LIGAND ; IDENTIFICATION ; METASTASIS ; P-SELECTIN ; PANCREATIC-CANCER ; TUMOR-INITIATING CELLS
    Abstract: OBJECTIVES: To evaluate CD24/CD44/CD47 cancer stem cell marker expressions in bladder cancer (BCa) and provide data on their prognostic significance for clinical outcome in patients undergoing radical cystectomy (RC). MATERIAL AND METHODS: Primary BCa tissue was used for xenograft studies. A tissue microarray was prepared using specimens from a cohort of 132 patients. All patients underwent RC for urothelial BCa between 2001 and 2010. Expression of CD24, CD44, and CD47 was examined in primary samples and xenografts by fluorescence-activated cell sorting. Populations of CD24(low)- and CD24(high)- expressing cells were sorted and evaluated for tumorigenicity in vivo. Tissue microarray was analyzed for CD24/CD44 staining intensity and tumor-specific vs. stromal cell staining. Associations with BCa survival, BCa stage, and lymph node status were evaluated by univariate and multivariate analyses. RESULTS: CD24 and CD44/CD47 expressions mark distinct cell populations within the normal urothelium as well as in BCa. CD24(high/low) expression was not sufficient to characterize CD24 as a BCa-initiating marker in in vivo primary xenotransplants. CD24 and CD44 expressions correlated with lower cancer-specific survival in patients. However, multivariate analyses of CD24 or CD44 did not demonstrate significantly increased hazards for cancer-specific death if analyzed together with stage, grade, and nodal status of patients. CONCLUSIONS: Cancer stem cell markers CD24/CD44/CD47 are differentially expressed in cells of urothelial BCa in patients undergoing RC and influence cancer-specific survival of patients. Further evaluation of CD24/CD44/CD47 protein expression could be of high therapeutic value in BCa. However, both CD24 and CD44 expressions cannot be regarded as independent prognostic parameters for patients undergoing RC.
    Type of Publication: Journal article published
    PubMed ID: 24631171
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  • 6
    Keywords: APOPTOSIS ; TOXICITY ; MECHANISM ; IDENTIFICATION ; RAT-LIVER METASTASIS ; RICIN-A-CHAIN ; PLANTS ; TRADITIONAL MEDICINE ; XIMENIA-AMERICANA ; RNA N-GLYCOSIDASE
    Abstract: The development of new anticancer drugs is a salient problem and the traditional use of plants is a potentially rich source of information for detecting new molecules with antineoplastic activity. Riproximin is a recently detected cytotoxic type II ribosome inactivating protein with high selectivity for certain tumor cell lines. Its activity was recognized as the main component in a plant powder used by African healers for treating cancer. By ribulose bisphosphate carboxylase gene sequencing analysis, the powder was identified to be derived from the plant Ximenia americana. The cDNA sequence of riproximin was identified, the protein was modeled to contain one A- and a B-chain, respectively, and a reliable purification procedure from kernels of X. americana was established. Riproximin displays high but differential antiproliferative activity in a panel of human and rodent cancer cell lines, with concentrations inhibiting cell proliferation by 50% (IC50 values) that diverge by a factor of 100. Consistent antineoplastic activity was detected in colorectal and pancreatic cancer liver metastasis models in rats. The cytotoxic mechanism of action was determined to be based on cellular uptake of riproximin followed by its A-chain prompted depurination of the 28S ribosomal RNA and induction of unfolded protein response. Riproximin's specificity depended on its B-chain connected binding to cell surface glycans, the presence of which is crucial for subsequent internalization into cells and cytotoxicity. These N- and O-glycans include bi- and tri-antennary NA structures (NA2/NA3) as well as Tn3 structures (clustered Tn antigen). Riproximin was found to crosslink proteins with N- and O-glycan structure, thus indicating both types of binding sites on its B chain. Due to this crosslinking ability, riproximin is expected to show prominent cytotoxicity towards cells expressing both, NA2/NA3 and clustered Tn structures. Apart from the properties of riproximin, the plant X. americana has been known for some medical uses in traditional African medicine, including various types of infections.
    Type of Publication: Journal article published
    PubMed ID: 24699434
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  • 7
    Keywords: TOOL ; RISK ; ANTIGEN ; IDENTIFICATION ; DUAL ROLE ; TRANSLATION ; ANTIANGIOGENIC ACTIVITY ; susceptibility loci ; MICRORNA EXPRESSION ; VAMP8
    Abstract: Prostate cancer is the second most common malignancy among men worldwide. Genome-wide association studies have identified 100 risk variants for prostate cancer, which can explain approximately 33% of the familial risk of the disease. We hypothesized that a comprehensive analysis of genetic variations found within the 3' untranslated region of genes predicted to affect miRNA binding (miRSNP) can identify additional prostate cancer risk variants. We investigated the association between 2,169 miRSNPs and prostate cancer risk in a large-scale analysis of 22,301 cases and 22,320 controls of European ancestry from 23 participating studies. Twenty-two miRSNPs were associated (P 〈 2.3 x 10(-5)) with risk of prostate cancer, 10 of which were within 7 genes previously not mapped by GWAS studies. Further, using miRNA mimics and reporter gene assays, we showed that miR-3162-5p has specific affinity for the KLK3 rs1058205 miRSNP T-allele, whereas miR-370 has greater affinity for the VAMP8 rs1010 miRSNP A-allele, validating their functional role. SIGNIFICANCE: Findings from this large association study suggest that a focus on miRSNPs, including functional evaluation, can identify candidate risk loci below currently accepted statistical levels of genome-wide significance. Studies of miRNAs and their interactions with SNPs could provide further insights into the mechanisms of prostate cancer risk.
    Type of Publication: Journal article published
    PubMed ID: 25691096
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  • 8
    Keywords: APOPTOSIS ; CANCER ; DENDRITIC CELLS ; IDENTIFICATION ; PROGRESSION ; LYMPHOCYTES ; TYROSINASE ; REGULATORY T-CELLS ; SUPPRESSOR-CELLS ; CHEMOTHERAPEUTIC-AGENTS
    Abstract: Chemotherapeutic agents such as paclitaxel applied in ultra-low, non-cytotoxic doses were previously shown to stimulate dendritic cell activity and anti-tumor immune responses upon vaccination in mouse transplantable tumor models. However, the mechanisms of these alterations-termed chemoimmunomodulation or chemomodulation-are still not clear. This study investigated the effect of paclitaxel applied in ultra-low, non-cytotoxic doses on the efficiency of immunization of healthy C57BL/6 mice with the peptide derived from tyrosinase related protein (TRP)-2 as a model melanoma antigen. Using an IFNgamma ELISPOT assay, it was found that administration of 1 mg paclitaxel/kg in combination with the peptide vaccination strongly increased the frequencies of TRP-2 specific spleen T-cells as compared to levels due to the vaccination alone. This was associated with a significant decrease in the levels of regulatory T-cells (T(reg)) and immature myeloid cells (known as a counterpart of myeloid derived suppressor cells [MDSC] in healthy mice). Such impairments of potential immunosuppressive cells were found to correlate with a strong increase in the amount of effector CD8(+) and CD4(+) T-cells in the bone marrow and spleen. Furthermore, in paclitaxel-treated mice, a significant augmentation of natural killer (NK) cell numbers in the bone marrow and their ability to produce IFNgamma were observed. In addition, the level of NK-T-cells in the lymph nodes was also increased. It is suggested that paclitaxel applied in ultra-low, non-cytotoxic doses may potentially enhance the efficacy of anti-tumor vaccinations by neutralizing immunosuppressive T(reg) and MDSC populations in tumor-bearing hosts.
    Type of Publication: Journal article published
    PubMed ID: 22449053
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  • 9
    Keywords: RECEPTOR ; CANCER ; TIME ; mechanisms ; IDENTIFICATION ; LOCALIZATION ; AKT ; SPINDLE ; SMALL-MOLECULE INHIBITOR ; KINESIN EG5
    Abstract: Timely and accurate assembly of the mitotic spindle is critical for the faithful segregation of chromosomes, and centrosome separation is a key step in this process. The timing of centrosome separation varies dramatically between cell types; however, the mechanisms responsible for these differences and its significance are unclear. Here, we show that activation of epidermal growth factor receptor (EGFR) signaling determines the timing of centrosome separation. Premature separation of centrosomes decreases the requirement for the major mitotic kinesin Eg5 for spindle assembly, accelerates mitosis, and decreases the rate of chromosome missegregation. Importantly, EGF stimulation impacts upon centrosome separation and mitotic progression to different degrees in different cell lines. Cells with high EGFR levels fail to arrest in mitosis upon Eg5 inhibition. This has important implications for cancer therapy because cells with high centrosomal response to EGF are more susceptible to combinatorial inhibition of EGFR and Eg5.
    Type of Publication: Journal article published
    PubMed ID: 23643362
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  • 10
    Keywords: SURVIVAL ; THERAPY ; SYSTEM ; TRIAL ; IDENTIFICATION ; chemotherapy ; MARKERS ; PERIPHERAL-BLOOD ; DISEASE PROGRESSION
    Abstract: BACKGROUND: To prospectively assess circulating tumor cell (CTC) status at baseline (CTCBL) and after one cycle of a new line of systemic therapy (CTC1C), and changes from CTCBL to CTC1C (CTC kinetics, CTCKIN) for their utility in predicting response, progression-free (PFS) and overall survival (OS) in metastatic breast cancer (MBC). METHODS: CTCBL and CTC1C status was determined as negative (-) or positive (+) for 〈 5 or 〉/= 5 CTCs/7.5 ml blood using CellSearch (Veridex). CTCKIN was categorized as favorable (CTC1C-) or unfavorable (CTC1C+). Tumor response was to be assessed every 2-3 months using the Response Evaluation Criteria in Solid Tumors (RECIST) criteria. Statistical analysis focused on the relation between CTC status and CTCKIN, and response, PFS, and OS. RESULTS: 133/393 (34%) patients enrolled were CTCBL+. CTC1C status after one cycle and radiological tumor response were assessed after median (range) periods of 1.2 (0.5-3.2) and 2.9 (0.5-4.8) months, respectively. 57/201 (28%) were CTC1C+. Median [95% confidence interval] PFS and OS (months) were significantly reduced in CTCBL+ vs. CTCBL- patients (PFS 4.7 [3.7-6.1] vs. 7.8 [6.4-9.2]; OS 10.4 [7.9-15.0] vs. 27.2 [22.3-29.9]), and for CTC1C+ vs. CTC1C- patients (PFS 4.3 [3.6-6.0] vs. 8.5 [6.6-10.4]; OS 7.7 [6.4-13.9] vs. 30.6 [22.6-not available]). Unfavorable CTCKIN was significantly associated with progressive disease. Multivariate Cox regression analysis revealed prognostic factors for shorter PFS (CTCBL+, persistent CTCs after one cycle, 〉/= 3rd-line therapy, and triple-negative receptor status) and shorter OS (CTCBL+, persistent CTCs after one cycle, bone-and-visceral/local metastases, 〉/= 3rd-line therapy, and triple-negative receptor status). CONCLUSIONS: CTCBL, CTC1C, and CTCKIN are predictive of outcome in MBC. Serial CTC enumeration is useful in tailoring systemic treatment of MBC. TRIAL REGISTRATION: Not applicable.
    Type of Publication: Journal article published
    PubMed ID: 25015676
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