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  • 1
    Keywords: RECEPTOR ; APOPTOSIS ; CANCER CELLS ; CELLS ; EXPRESSION ; GROWTH ; tumor ; TUMOR-CELLS ; carcinoma ; Germany ; human ; INHIBITION ; PATHWAY ; PATHWAYS ; DEATH ; HEPATOCELLULAR-CARCINOMA ; PROTEINS ; RNA ; DRUG ; MONOCLONAL-ANTIBODY ; TUMORS ; RELEASE ; TUMOR-NECROSIS-FACTOR ; ACTIVATION ; LIGAND ; MECHANISM ; FAMILY ; DOMAIN ; INDUCTION ; mechanisms ; DOWN-REGULATION ; CYTOCHROME-C ; MITOCHONDRIA ; UNITED-STATES ; RECEPTORS ; OVEREXPRESSION ; TUMOR CELLS ; Bcl-2 ; HUMAN HEPATOCYTES ; TRAIL-INDUCED APOPTOSIS ; APOPTOSIS-INDUCING LIGAND ; CD95 ; CASPASE ; INHIBITORS ; signaling ; FAMILIES ; SOLID TUMORS ; CYCLOOXYGENASE-2 ; TUMOR-CELL ; death receptor ; downregulation ; function ; caspases ; DRUGS ; cyclooxygenase ; RELEVANCE ; NECROSIS ; MCL-1 ; CELECOXIB-INDUCED APOPTOSIS ; PRIMARY HUMAN HEPATOCYTES
    Abstract: Inhibition of cyclooxygenase (COX)-2 elicits chemopreventive and therapeutic effects in solid tumors that are coupled with the induction of apoptosis in tumor cells. We investigated the mechanisms by which COX-2 inhibition induces apoptosis in hepatocellular carcinoma (HCC) cells. COX-2 inhibition triggered expression of the CD95, tumor necrosis factor (TNIF)-R, and TNF-related apoptosis-inducing ligand (TRAIL)-R1 and TRAIL-R2 death receptors. Addition of the respective specific ligands further increased apoptosis, indicating that COX-2 inhibition induced the expression of functional death receptors. Overexpression of a dominant-negative Fas-associated death domain mutant reduced COX-2 inhibitor-mediated apoptosis. Furthermore, our findings showed a link between COX-2 inhibition and the mitochondrial apoptosis pathway. COX-2 inhibition led to a rapid down-regulation of myeloid cc leukemia-1 (Mcl-1), an antiapoptotic member of the Bcl-2 family, followed by translocation of Bax to mitochondria and cytochrome c release front mitochondria. Consequently, overexpression of Mcl-1 led to inhibition of COX-2 inhibitor-mediated apoptosis. Furthermore, blocking endogenous Mcl-1 function using a small - interfering RNA approach enhanced COX-2 inhibitor-mediated apoptosis. It is of clinical importance that celecoxib acted synergistically with chemotherapeutic drugs in the induction of apoptosis in HCC cells. The clinical relevance of these results is further substantiated by the finding that COX-2 inhibitors did not sensitize primary human hepatocytes toward chemotherapy-induced apoptosis. In conclusion, COX-2 inhibition engages different apoptosis pathways in HCC cells stimulating death receptor signaling, activation of caspases, and apoptosis originating from mitochondria
    Type of Publication: Journal article published
    PubMed ID: 16849551
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  • 2
    Abstract: Merkel cell carcinoma (MCC) is a highly malignant skin cancer characterized by early metastases and poor survival. Although MCC is a rare malignancy, its incidence is rapidly increasing in the U.S. and Europe. The discovery of the Merkel cell polyomavirus (MCPyV) has enormously impacted our understanding of its etiopathogenesis and biology. MCCs are characterized by trilinear differentiation, comprising the expression of neuroendocrine, epithelial and B-lymphoid lineage markers. To date, it is generally accepted that the initial assumption of MCC originating from Merkel cells (MCs) is unlikely. This is owed to their post-mitotic character, absence of MCPyV in MCs and discrepant protein expression pattern in comparison to MCC. Evidence from mouse models suggests that epidermal/dermal stem cells might be of cellular origin in MCC. The recently formulated hypothesis of MCC originating from early B-cells is based on morphology, the consistent expression of early B-cell lineage markers and the finding of clonal immunoglobulin chain rearrangement in MCC cells. In this review we elaborate on the cellular ancestry of MCC, the identification of which could pave the way for novel and more effective therapeutic regimens.
    Type of Publication: Journal article published
    PubMed ID: 28693804
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  • 3
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    FEBS Letters 270 (1990), S. 229-232 
    ISSN: 0014-5793
    Keywords: Activation of double-stranded RNA degradation ; Bovine seminal ribonuclease ; Interferon-γ Interferon-α ; Mechanism of cell growth inhibition by interferons ; Ribonuclease A (RNase A)
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Cell biology and toxicology 14 (1998), S. 121-132 
    ISSN: 1573-6822
    Keywords: protease ; proteolysis ; apoptosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Proteolytic cleavage of a limited number of cellular proteins is a central biochemical feature of apoptosis. Aspartate-specific cysteine proteases, the so-called ‘caspases’, are the main enzymes involved in this process. At least ten homologues of interleukin-1β converting enzyme (ICE), the first described human caspase, have been identified so far. The purified active proteins are heterodimers with a long and a short subunit derived from a common inactive precursor. Crystallized ICE has an original tetrameric structure. The various caspases tend to show high degrees of homology around the active site Cys. Proteolysis by caspases minimally requires a tetrapeptide substrate in which Asp is an absolute requirement in P1 position, the P4 substrate residue is unique to each homologue, and much more widespread amino acid substitution is observed in P2 and P3. Caspase activation might involve a proteolytic cascade similar to that of the coagulation cascade but the molecular ordering of these proteases in vivo remains to be established clearly. Calpains, serine proteases, granzymes and the proteasome–ubiquitin pathway of protein degradation are other proteolytic pathways that have been suggested to play a role in apoptosis. Substrate proteins can be either activated or degraded during cell death and the consequences of their cleavage remains mostly ill-understood. Nevertheless, the recent demonstration that protease inhibitors can rescue mice undergoing acute liver destruction indicates the accuracy of therapeutic strategies aiming to inhibit cell death-associated proteolysis.
    Type of Medium: Electronic Resource
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