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Biomedical subjects

C C Geilen

Publications and source records attributed to C C Geilen.

At least 19 recordsLinked to original sources
PubMed2006

Resistance of melanoma cells to TRAIL does not result from upregulation of antiapoptotic proteins by NF-kappaB but is related to downregulation of initiator caspases and DR4.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has attracted considerable attention as a novel anticancer agent. However, its efficiency may be diminished by occurring resistance in cancer cells. The mechanisms of TRAIL resistance in melanoma are still unsolved. Here we show for the first time that TRAIL-induced activation of NF-kappaB occurs in apoptosis-sensitive melanoma cell lines through TRAIL receptor 1/death receptor 4 (TRAIL-R1/DR4), whereas TRAIL failed to activate nuclear factor kappa B (NF-kappaB) in melanoma cells positive only for TRAIL receptor 2/death receptor 5 (TRAIL-R2/DR5). However, activation of NF-kappaB by TRAIL was not associated with enhanced expression of antiapoptotic factors: cellular FLICE-inhibitory protein (c-FLIP), Bcl-x(L), X-linked inhibitor of apoptosis protein (XIAP), Survivin, Livin. Rather in one of the cell lines, TRAIL induced the downregulation of DR4. In an established cell culture model for TRAIL resistance and regained TRAIL sensitivity, resistance was neither associated with increased NF-kappaB activity by TRAIL nor by an increased expression of antiapoptotic proteins. However, significant downregulation of caspase-8, caspase-10 and of DR4 was characteristic for TRAIL-resistant, DR4-positive melanoma cells, and regained TRAIL sensitivity coincided with re-expression of these factors. Sensitivity was also largely retained after their exogenous overexpression. Thus, initiator caspases and DR4 rather than NF-kappaB may control melanoma cell sensitivity to TRAIL, and strategies, which result in their upregulation, may be useful for enhancement of TRAIL sensitivity.

Apoptosis Regulatory Proteins↗
PubMed2006

A novel Bcl-x splice product, Bcl-xAK, triggers apoptosis in human melanoma cells without BH3 domain.

Pro- and antiapoptotic proteins of the large Bcl-2 family are critical regulators of apoptosis via the mitochondrial pathway. Whereas antiapoptotic proteins of the family share all four Bcl-2 homology domains (BH1-BH4), proapoptotic members may lack some of these domains, but all so far described proapoptotic Bcl-2 proteins enclose BH3. The bcl-x gene gives rise to several alternative splice products resulting in proteins with distinct functions as the antiapoptotic Bcl-xL and proapoptotic Bcl-xS. Here, we describe a novel Bcl-x splice product of 138 amino acids termed Bcl-xAK (Atypical Killer), which encloses the Bcl-2 homology domains BH2 and BH4 as well as the transmembrane domain, but lacks BH1 and BH3. Weak endogenous expression of Bcl-xAK was seen in melanoma and other tumor cells. Interestingly, its overexpression by applying a tetracycline-inducible expression system resulted in significant induction of apoptosis in melanoma cells, which occurred in synergism with drug-induced apoptosis. After exogenous overexpression, Bcl-xAK was localized both in mitochondrial and in cytosolic cell fractions. By these findings, a completely new class of Bcl-2-related proteins is introduced, which promotes apoptosis independently from the BH3 domain and implies additional, new mechanisms for apoptosis regulation in melanoma cells.

Alternative Splicing↗
PubMed2006

Three coexisting lymphomas in one patient: genetically related or only a coincidence?

The simultaneous manifestation of different lymphomas in the same patient or even in the same tissue, defined as composite lymphoma, is very rare. The exceptional case of a patient who, presented with simultaneous manifestation of three different lymphomas after 30 years of successful treatment of a nodal T cell lymphoma is reported here. The three lymphomas were: (1) primary cutaneous marginal zone B cell lymphoma (MZBL); (2) nodal Epstein-Barr virus (EBV)-associated classic Hodgkin's lymphoma (cHL) of the B cell type; and (3) peripheral T cell lymphoma coexisting in the skin and cervical lymph node. Immunohistochemical and molecular analyses showed different clonal origins of EBV-negative cutaneous MZBL and EBV-positive B cell cHL and, in addition, the presence of the same clonal T cell population in the skin and lymph node. The simultaneous occurrence of three different, clonally unrelated lymphomas in one patient at the same time has not been reported yet.

Aged↗
PubMed2004

Nitrogen-containing bisphosphonates inhibit cell cycle progression in human melanoma cells.

Cutaneous melanoma is one of the highly malignant human tumours, due to its tendency to generate early metastases and its resistance to classical chemotherapy. We recently demonstrated that pamidronate, a nitrogen-containing bisphosphonate, has an antiproliferative and proapoptotic effect on different melanoma cell lines. In the present study, we compared the in vitro effects of three different bisphosphonates on human melanoma cell lines and we demonstrated that the two nitrogen-containing bisphosphonates pamidronate and zoledronate inhibited the proliferation of melanoma cells and induced apoptosis in a dose- and time-dependent manner. Moreover, cell cycle progression was altered, the two compounds causing accumulation of the cells in the S phase of the cycle. In contrast, the nonaminobisphosphonate clodronate had no effect on melanoma cells. These findings suggest a direct antitumoural effect of bisphosphonates on melanoma cells in vitro and further support the hypothesis of different intracellular mechanisms of action for nitrogen-containing and nonaminobisphosphonates. Our data indicate that nitrogen-containing bisphosphonates may be a useful novel therapeutic class for treatment and/or prevention of melanoma metastases.

Antimetabolites↗
PubMed2004

Cutaneous T cell lymphoma and classic Hodgkin lymphoma of the B cell type within a single lymph node: composite lymphoma.

Composite lymphomas are defined as two unrelated, morphologically and genetically distinct lymphomas occurring at the same point in time within the same tissue or organ. Since their original definition, several composite lymphomas have been reported exclusively based on morphological grounds. However, with the application of immunohistological and molecular biological techniques it has become evident that many so called "composite" lymphomas do not fulfil the necessary criteria, because they merely represent two different morphological phenotypes of the same malignant clone. This report describes the manifestation of a true composite lymphoma within a single cervical lymph node, which is composed of a cutaneous T cell lymphoma and a classic Hodgkin lymphoma of B cell type--a very rare finding indeed.

Aged↗
PubMed2004

Transition of Sézary syndrome into mycosis fungoides after complete clinical and molecular remission under extracorporeal photophoresis.

Mycosis fungoides (MF) and Sezary syndrome (SS) are the most common clinical variants of cutaneous T cell lymphoma. Although thought to be closely related to mature T helper cells, the relation between the neoplastic cells in MF and SS is still not fully clarified. This report describes a patient with complete remission of SS under treatment with extracorporeal photophoresis (ECP), who subsequently developed typical plaques of MF and large cell lymphoma (LCL). Serial polymerase chain reaction analyses confirmed identical T cell receptor beta and gamma gene rearrangements in SS, MF, and LCL, and complete disappearance of the circulating malignant T cell clone from the peripheral blood after ECP. These findings indicate that the neoplastic cells in SS, MF, and LCL are derived from a common precursor T cell, despite the change in clinical phenotype.

Aged↗
PubMed2003

Regulation of PDGF and PDGF receptor in cultured dermal papilla cells and follicular keratinocytes of the human hair follicle.

Platelet-derived growth factor (PDGF) is a potent mitogenic factor for many cell types and has been shown to be important in follicular development and vasculogenesis. In this study, we examined the expression pattern of both PDGF factors and their corresponding receptors in mesenchyme-derived dermal papilla cells (DPCs) and epithelial follicular keratinocytes (FKs). Both types of PDGF receptors are expressed in FKs, whereas DPCs only express PDGF receptor beta on the protein level, a finding also seen in whole organ cultures. By examining the expression of PDGF ligands, we were able to show that cultured FKs synthesize both PDGF-A and PDGF-B, whereas, DPCs only express PDGF-A. As immunomodulatory cytokines were shown to affect hair growth, we investigated the effects of IL-1beta, IL-4, TNF-alpha, TGF-beta and IFN-gamma on the expression levels of PDGF factors in cultured DPCs and FKs. Interestingly, we could show a significant down-regulatory effect by catagen-inducing cytokines like IL-1beta or IFN-gamma, suggesting a possible involvement of PDGF signaling in the induction of catagen. The question concerning the latter hypothesis remains to be elucidated in further studies on whole organ cultures.

Autocrine Communication↗
PubMed2003

Differential involvement of ceramide in TNFalpha-mediated activation of NF-kappaB in primary human keratinocytes and HaCaT keratinocytes.

The involvement of ceramide signaling in tumor necrosis factor alpha (TNFalpha) mediated nuclear transcription factor kappa B (NF-kappaB) activation was studied. The cell response modifier ceramide has been shown to modulate apoptosis, cell differentiation and cell proliferation in different cell populations. Sphingomyelin hydrolysis is one pathway generating intracellular ceramide increase. Previously, we could show that TNFalpha induces a ceramide increase in primary human keratinocytes and HaCaT keratinocytes and consequently apoptosis was initiated. It is well known that TNFalpha activates the transcription factor NF-kappaB, but there have been controversial reports on the role of ceramide in TNFalpha-mediated NF-kappaB activation. Here we show by different lines of experimental evidence that TNFalpha is a strong inducer of NF-kappaB in both cell types, whereas C2-ceramide failed to activate NF-kappaB in HaCaT keratinocytes in contrast to primary keratinocytes.

Amides↗
PubMed2002

The bisphosphonate pamidronate induces apoptosis in human melanoma cells in vitro.

Pamidronate belongs to the class of nitrogen-containing bisphosphonates that are potent inhibitors of bone resorption frequently used for the treatment of osteoporosis and cancer-induced osteolysis. The inhibition of osteoclasts' growth has been suggested as the main mechanism of the inhibitory effect of pamidronate on bone metastases. Recent findings indicated that bisphosphonates also have a direct apoptotic effect on other types of tumour cells. Nitrogen-containing bisphosphonates were shown to inhibit farnesyl diphosphate synthase, thus blocking the synthesis of higher isoprenoids. By this mechanism they inactivate monomeric G-proteins of the Ras and Rho families for which prenylation is a functional requirement. On the background of the known key role of G-proteins in tumorigenesis, we investigated a possible beneficial use of pamidronate in the treatment of malignant melanoma. Our results indicate that pamidronate inhibits the cell growth and induces apoptosis in human melanoma cells in vitro. Susceptibility to pamidronate did not correlate to CD95 ligand sensitivity or p53 mutational status. Furthermore it is interesting to note that overexpression of bcl-2 did not abolish pamidronate-induced apoptosis. These data suggests that pamidronate has a direct anti-tumour effect on malignant melanoma cells, independently of the Bax/Bcl-2 level.

Antineoplastic Agents↗
PubMed2002

Decreased proliferation of human melanoma cell lines caused by antisense RNA against translation factor eIF-4A1.

Control of translation initiation was recognised as a critical checkpoint for cell proliferation and tumorigenesis. In human melanoma cells, we have previously reported consistent overexpression of translation initiation factor eIF-4A1. Here, we investigated by transfection of antisense constructs its significance for the control of melanoma cell growth. The tetracycline-inducible expression system was established in melanoma cells, and three fragments of the 5'-, central-, and 3'-portion of the eIF-4A1 cDNA were subcloned in antisense and in sense orientation after a tetracycline inducible promoter. Significant proliferation decrease was obtained after transient transfection and induction of antisense RNA directed against the 5'- and the central portion (up to 10%), whereas, no effects were seen after induction of the 3'-fragment and the sense controls. Cell clones stably transfected with the central antisense fragment revealed after doxycycline induction reduced expression of endogeneous eIF-4A1 mRNA correlated with decreased proliferation rates (up to 6%). These data demonstrate the applicability of antisense strategies against translation factors in melanoma cells. Translation initiation factor eIF-4A1 contributes to the control of melanoma cell proliferation and may be taken into consideration when scheduling new therapeutic approaches targeting the translational control.

Anti-Bacterial Agents↗
PubMed2002

Magnetic bead RT-PCR: establishment of a new method for detecting circulating melanoma cells.

This study was performed to detect circulating melanoma cells in peripheral blood using a novel method based on magnetic-activated cell separation (MACS) followed by a nested reverse transcriptase-polymerase chain reaction (RT-PCR) for tyrosinase and MART-1 mRNA. Samples to be tested were enriched for tumour cells either by isolating melanoma cells using two anti-melanoma antibodies (MART-1 and HMB-45) or by CD45 depletion of the non-melanoma cell fraction. The tumour cell-enriched fractions were subjected to mRNA isolation using oligo-deoxythymidylate (oligo-dT) magnetic beads followed by a nested RT-PCR. Sensitivity was assessed by spiking experiments and compared with a commonly used total RNA isolation system previously established in our department. Positive isolation of melanoma cells showed insufficient sensitivity, whereas negative isolation by depletion of leukocytes showed a detection limit of at least one melanoma cell per millilitre of whole blood. In further experiments, the depletion assay was applied to 25 peripheral blood samples of melanoma patients. The preliminary data obtained from the new method indicate a comparable detection rate to the established total RNA extraction method. However, not all the results were concordant. Therefore, future experiments need to be performed with a statistically greater number of patients.

Adult↗
PubMed2001

The Bax/Bcl-2 ratio determines the susceptibility of human melanoma cells to CD95/Fas-mediated apoptosis.

Defective cytochrome c release and the resulting loss of caspase-3 activation was recently shown to be essential for the susceptibility of human melanoma cells to CD95/Fas-induced apoptosis. Cytochrome c release from mitochondria is regulated by the relative amounts of apoptosis-promoting and apoptosis-inhibiting Bcl-2 proteins in the outer membrane of these organelles. The assignment of Bax/Bcl-2 ratios by quantitative Western blotting in 11 melanoma cell populations revealed a relation to the susceptibility to CD95-mediated apoptosis. We could show that a low Bax/Bcl-2 ratio was characteristic for resistant cells and a high Bax/Bcl-2 ratio was characteristic for sensitive cells. Low Bax expression was not a consequence of mutations in the p53 coding sequence. The Bax/Bcl-2 ratio was also in clear correlation with sensitivity to another cell death inducer, N-acetylsphingosine. Furthermore, Bcl-2 overexpression abolished apoptosis triggered by both apoptotic stimuli, confirming the critical role of the Bax/Bcl-2 ratio as a rheostat that determines the susceptibility to apoptosis in melanoma cells by regulating mitochondrial function. Interestingly, some chemotherapeutics lead to the activation of death pathways by CD95L upregulation, ceramide generation, direct activation of upstream caspases, or upregulation of proapoptotic genes. Taken together, these signals enter the apoptotic pathway upstream of mitochondria, resulting in activation of this central checkpoint. We therefore assumed that apoptosis deficiency of malignant melanoma can be circumvented by drugs directly influencing mitochondrial functions. For this purpose we used betulinic acid, a cytotoxic agent selective for melanoma, straightly perturbing mitochondrial functions. In fact, betulinic acid induced mitochondrial cytochrome c release and DNA fragmentation in both CD95-resistant and CD95-sensitive melanoma cell populations, independent of the Bax/Bcl-2 ratio.

Antineoplastic Agents, Phytogenic↗
PubMed2001

Nodular and bullous cutaneous mastocytosis of the xanthelasmoid type: case report.

Severe generalized nodular and bullous mastocytosis of the xanthelasmoid type is described in a 7-month-old boy. Reddish to yellowish-brown xanthelasmoid papules and nodules first developed in the inguinal region a few weeks after birth and then progressively spread to cover nearly the entire body surface. There was severe pruritus and recurrent episodes of blistering. The diagnosis of cutaneous mastocytosis of the xanthelasmoid type with subepidermal bullae was confirmed by skin biopsies showing solid and deeply penetrating infiltrates of metachromatic mast cells under light and electron microscopy. Systemic involvement of other organs, however, was excluded by bone scintigraphy, abdominal ultrasound, bone marrow aspiration and echocardiography. The extensive skin involvement was reflected in highly elevated urinary levels of histamine (263.4 microg L(-1)) and its metabolite N-methylimidazole acetic acid (20.8 mg L(-1)). The patient was systematically well and received only symptomatic treatment. Over a period of 1 year, the condition gradually improved, and the skin lesions began to flatten and regress.

Biopsy↗