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Query: UMLS:C0025202 (melanoma)
 69,561 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cancer cells of different solid and hematopoietic tumors express growth factors in respective stages of tumor progression, which by autocrine and paracrine effects enable them to grow autonomously. Here we show that the murine B16 melanoma cell line and two human primary cultures of stomach adenocarcinoma and glioblastoma multiforme (GBM) constitutively secrete interleukin (IL)-10 in an autocrine/paracrine manner. This cytokine is essential for tumor cell proliferation because its neutralization decreases clonogenicity of malignant cells, whereas addition of recombinant IL-10 increases cell proliferation. The immunomodulator ammonium trichloro(dioxoethylene-o,o')tellurate (AS101) decreased cell proliferation by inhibiting IL-10. This activity was abrogated by exogenous addition of recombinant IL-10. IL-10 inhibition by AS101 results in dephosphorylation of Stat3, followed by reduced expression of Bcl-2. Moreover, these activities of AS101 are associated with sensitization of tumor cells to chemotherapeutic drugs, resulting in their increased apoptosis. More importantly, AS101 sensitizes the human aggressive GBM tumor to paclitaxel both in vitro and in vivo by virtue of IL-10 inhibition. AS101 sensitizes GBM cells to paclitaxel at concentrations that do not affect tumor cells. This sensitization can also be obtained by transfection of GBM cells with IL-10 antisense oligonucleotides. Sensitization of GBM tumors to paclitaxel (Taxol) in vivo was obtained by either AS101 or by implantation of antisense IL-10-transfected cells. The results indicate that the IL-10 autocrine/paracrine loop plays an important role in the resistance of certain tumors to chemotherapeutic drugs. Therefore, anti-IL-10 treatment modalities with compounds such as AS101, combined with chemotherapy, may be effective in the treatment of certain malignancies.
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PMID:Ammonium trichloro(dioxoethylene-o,o')tellurate (AS101) sensitizes tumors to chemotherapy by inhibiting the tumor interleukin 10 autocrine loop. 1499 48

Malignant melanoma is a prime example of a treatment-resistant tumor with poor prognosis. Even with innovative treatment regimens, response rates remain low, and the duration of responses is short. More than 90% of all melanomas express the antiapoptotic protein Bcl-2, shown to contribute to a chemoresistant phenotype in melanoma. We previously demonstrated that antisense-mediated inhibition of Bcl-2 sensitizes malignant melanoma to apoptosis-inducing treatment modalities. In the present study, we evaluated synthetic small interfering RNA (siRNA) compounds targeting Bcl-2 as a novel approach to downregulate Bcl-2 expression in melanoma cells. siRNA treatment led up to a 19-fold reduction of bcl-2 mRNA levels and only barely detectable Bcl-2 protein expression at low nanomolar concentrations. Silencing of Bcl-2 in melanoma cells by specific siRNA led to a moderate increase in apoptotic cell death and inhibition of cell growth. However, if siRNA compounds targeting Bcl-2 were combined with the apoptosis-inducing chemotherapeutic agent cisplatin, a massive increase in apoptotic cell death compared with controls was observed. Notably, the combination of Bcl2 siRNA and low-dose cisplatin resulted in a supra-additive effect, with nearly complete suppression of cell growth, whereas cell growth in cisplatin-only-treated cells was only moderately affected (96% vs. 25%, p < 0.001). These findings underline a key role for Bcl-2 in conferring chemoresistance to melanoma and highlight Bcl-2 siRNA strategies as novel and highly effective tools, with the potential for future targeted therapy of malignant melanoma.
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PMID:Small interfering RNA targeting bcl-2 sensitizes malignant melanoma. 1500 Aug 30

In this study of lectin-induced apoptosis we found that wheat germ agglutinin (WGA) initiated an accelerated type of programmed cell death developing after only 30 min of incubation with tumor cells. To analyze possible mechanisms, studies were focused using the WGA lectin whose carbohydrate specificity is well defined. We found that WGA could induce apoptosis by binding to either N-acetylneuraminic acid or N-acetylglucosamine (GlcNAc) on the cell surface of normal and malignant cells. We also showed that it is unlikely that WGA triggers apoptosis by binding to the carbohydrate portion of Fas. CrmA gene transfection did not inhibit WGA-mediated apoptosis of Jurkat cells. In addition, Jurkat-R cells selected for resistance to Fas signaled apoptosis manifested high sensitivity to WGA as did Fas-negative BL6 melanoma cells. WGA-induced apoptosis is also caspase-3-independent and was found to be triggered via a mitochondrial pathway. WGA induced a loss of transmembrane potential, disruption of the inner mitochondria membrane, and release of cytochrome c and caspase-9 activation after 30 min of cell interaction. Interestingly, Bcl-2 gene transfection did not affect sensitivity of Jurkat cells to WGA. The Jurkat-R subline that has been shown to be Bax and Bak deficient and resistant to various apoptotic signals was highly sensitive to WGA-induced apoptosis. In summary, WGA triggers a unique pattern of apoptosis that is extremely fast, Fas- and caspase-3-independent, and is mediated via a mitochondrial pathway. However, its mitochondrial component is unrestrained by the loss of Bax and Bak or the upregulation of Bcl-2 expression.
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PMID:A novel apoptotic pathway as defined by lectin cellular initiation. 1500 40

Two diterpenoids, oridonin (1) and ponicidin (2), were isolated from the 95% ethanol extract of Rabdosia rubescens and were evaluated for antiproliferative activity on cancer cells and human peripheral blood mononuclear cells (PBMC) in vitro. Oridonin has much more potent cytotoxic effects on four tumor cells (human melanoma A375-S2, human cervical cancer HeLa, human breast adenocarcinoma MCF-7, murine fibrosarcoma L929) than does ponicidin. The growth-inhibitory activity of oridonin for A375-S2 cells was more potent than that for the other cell lines, with an IC50 of 15.1 +/- 1.2 micromol L(-1). Treatment with oridonin (34.3 micromol L(-1)) for 12 h significantly inhibited A375-S2 cell growth, and showed weaker cytotoxicity against PBMC. By contrast, ponicidin markedly inhibited the growth of PBMC under the same conditions. When caspases-3 and -8 were activated at early stages after treatment of A375-S2 cells with oridonin (34.3 micromol L(-1)), apoptotic bodies were formed, nuclear damage was observed by Hoechst 33258 staining and DNA fragmentation was exhibited. In addition, oridonin increased the expression of the apoptosis inducer, Bax, promoted the release of cytochrome c without affecting Bcl-2 expression, and activated down-stream caspase-9 in the mitochondrial pathway. These observations indicated that an appropriate dose of oridonin gave an initial premitochondrial phase that involved the Bcl-2 family of the pro-apoptotic protein Bax that required the participation of caspase-9 and caspase-3. However, on treatment with oridonin (137.4 micromol L(-1)) for 12 h, the majority of A375-S2 cells underwent necrosis as measured by an LDH activity-based assay. Our results suggest that oridonin induces A375-S2 cell death on the balance of apoptosis and necrosis.
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PMID:Oridonin induced A375-S2 cell apoptosis via bax-regulated caspase pathway activation, dependent on the cytochrome c/caspase-9 apoptosome. 1500 59

Photodynamic therapy (PDT) is a promising therapeutic modality that utilizes a combination of a photosensitizer and visible light for the destruction of diseased tissues. Using human-pigmented melanoma cells, we examined the photokilling efficacy of new silicon-phthalocyanines (SiPc) that bore bulky axial substituents. The bis(cholesteryloxy) derivate (Chol-O-SiPc) displayed the best in vitro photokilling efficacy (LD(50) = 6-8 x 10(-9) M) and was seven to nine times more potent than chloro-aluminium Pc (ClAlPc), a known photosensitizer used as a reference. Although Chol-O-SiPc was half as potent as ClAlPc for promoting photo-oxidative membrane damage in a cell-free assay, early events of mitochondrion-mediated apoptosis upon PDT were triggered much faster, as demonstrated by kinetics studies examining cells with permeabilized mitochondrial membranes, cytochrome c release and caspase-9 activation. Inhibition of caspase-9 activity by a substrate analogue argued for its central role in the proapoptotic events leading to cell death by Chol-O-SiPc PDT. In addition, immunoblots showed that Bcl-2 antiapoptotic oncoprotein was not a primary target of Chol-O-SiPc in M3Dau cells treated with PDT. Conclusively, Chol-O-SiPc is a useful new photosensitizer with the property of triggering cell apoptosis mediated by mitochondria.
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PMID:Killing efficacy of a new silicon phthalocyanine in human melanoma cells treated with photodynamic therapy by early activation of mitochondrion-mediated apoptosis. 1500 14

Histone deacetylase (HDAC) inhibitors have attracted much interest because of their ability to arrest cell growth, induce cell differentiation, and in some cases, induce apoptosis of cancer cells. In the present study, we have examined a new HDAC inhibitor, suberic bishydroxamate (SBHA), for its effect on a panel of human melanoma cell lines. We report that it induces varying degrees of apoptosis in the melanoma lines but not in melanocytes and fibroblasts. Induction of apoptosis was caspase dependent and was associated with induction of changes in mitochondrial membrane permeability, which could be inhibited by overexpression of Bcl-2. The changes in mitochondria were independent of caspase activation and were associated with changes in conformation of Bax. SBHA down-regulated several key antiapoptotic proteins including X-linked inhibitor of apoptosis and the Bcl-2 family proteins, Bcl-XL and Mcl-1. In contrast, it induced up-regulation of the Bcl-2 family proapoptotic proteins, Bim, Bax, and Bak. In addition, SBHA induced relocation of the protein Bim to mitochondria and its association with Bcl-2. De novo protein synthesis was required for initiation of apoptosis in that the protein synthesis inhibitor, cycloheximide, inhibited SBHA-induced conformational changes in Bax as well as changes in mitochondrial membrane permeability and activation of caspase-3. These results suggest that SBHA induces apoptosis by changing the balance between proapoptotic and antiapoptotic proteins in melanoma cells. The protein Bim may be a key initiator of apoptosis in cells treated with SBHA.
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PMID:The histone deacetylase inhibitor suberic bishydroxamate regulates the expression of multiple apoptotic mediators and induces mitochondria-dependent apoptosis of melanoma cells. 1507 86

The expression pattern of integrin-type cell adhesion receptors is often changed during malignant transformation. In the present work, we studied the prognostic significance of beta1 and alphav integrin chains for survival of patients with metastatic melanoma. The expression levels of beta1 integrin were also compared with those of Bcl-2, an anti-apoptotic protein, the presence of which is associated with treatment response and survival in melanoma. The expression of beta1 and alphav integrins in 68 melanoma metastases obtained from 55 patients treated with combined chemoimmunotherapy was studied by immunohistochemistry using anti-beta1 and anti-alphav antibodies. The patients were divided into two groups (using a cut-off point of >/= 81%) for beta1 integrin expression levels and into three categories (negative/low, median, high) for alphav integrin expression levels. All tumours were positive for beta1 integrin, and the tumours (n = 6) which had the highest alphav score were also strongly positive for beta1 (94%; P = 0.0055). Patients (n = 43) with 80% or less beta1 integrin-positive tumour cells in their samples had a median disease-free survival (DFS) of 17.0 months, and patients (n = 12) with 81% or more beta1 integrin-positive tumour cells had a DFS of only 5.7 months (P = 0.0001). Patients (n = 32) with low alphav integrin expression levels had shorter DFS (median 12.3 months; P = 0.0146) than patients (n = 20) with median expression levels (median 16.7 months; P = 0.0146). However, three patients who had a very strong alphav expression in their tumours had a median DFS of only 1.8 months (P = 0.0146). Median level expression of beta1 integrin was associated with the presence of Bcl-2 in tumour cells (P = 0.0033). Our results suggest that beta1 and alphav integrin chains are independently expressed in metastatic melanoma and may have an effect on the metastatic potential of melanoma cells.
Melanoma Res 2004 Feb
PMID:Integrin chains beta1 and alphav as prognostic factors in human metastatic melanoma. 1509 Nov 91

Melanoma cells are relatively resistant to Apo2L/TRAIL (TNF-related apoptosis-inducing ligand). We postulated that resistance might result from higher expression of inhibitors of apoptosis including Bcl-2, FLIP (FLICE-like inhibitory protein) or IAPs such as XIAP (X-linked inhibitor of apoptosis) or survivin. Compared to scrambled or mismatch controls, targeting individual inhibitors with siRNA (si-Bcl-2, si-XIAP, si-FLIP or si-Surv), followed by Apo2L/TRAIL resulted in marked increase in apoptosis in melanoma cells. Compared to Bcl-2 or FLIP, siRNAs against XIAP and survivin were most potent in sensitizing melanoma cells. A similar substantial increase in apoptosis was seen in renal carcinoma cells (SKRC-45, Caki-2), following the inhibition of either XIAP or survivin by siRNAs. Apo2L/TRAIL treatment in IAP-targeted cells resulted in cleavage of Bid, activation of caspase-9 and cleavage of PARP (poly ADP-ribose polymerase). Thus, Apo2L/TRAIL resistance can be overcome by interfering with expression of inhibitors of apoptosis regulating both extrinsic (death receptor) or intrinsic (mitochondrial) pathways of apoptosis in melanoma cells.
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PMID:Downregulation of Bcl-2, FLIP or IAPs (XIAP and survivin) by siRNAs sensitizes resistant melanoma cells to Apo2L/TRAIL-induced apoptosis. 1511 63

Bypassing molecular mechanisms of apoptosis deficiency may be of great utility for the successful treatment of malignant tumors. We have discovered that imiquimod, a small-molecule immunomodulator, exerts rather tumor-selective direct pro-apoptotic activity in vivo and in vitro towards cutaneous metastases of malignant melanoma, an aggressive skin tumor. This pro-apoptotic activity was not detectable with resiquimod, a closely related structural analogue whose pro-inflammatory activity is even greater than that of imiquimod. Unresponsiveness of some melanoma metastases to imiquimod in vivo corresponded to resistance towards imiquimod-induced apoptosis in vivo and in vitro. At the molecular level, the pro-apoptotic activity of imiquimod was independent of membrane-bound death receptors, but depended on Bcl-2 expression as demonstrated by overexpression of Bcl-2 in melanoma cells. Imiquimod is the first topical compound with the potential to bypass molecular mechanisms of apoptosis deficiency, a concept that may be relevant for other tumors as well.
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PMID:Death receptor-independent apoptosis in malignant melanoma induced by the small-molecule immune response modifier imiquimod. 1514 Feb 51

Malignant melanoma is known to display tremendous histologic diversity. One rare variant is the rhabdoid phenotype, so called because of the appearance of cells resembling rhabdomyoblasts seen in malignant rhabdoid tumors of the kidney. We present the histologic, immunohistochemical, and ultrastructural features of a malignant melanoma composed entirely of rhabdoid cells. A 62-year-old man presented with a 6.5-cm lung mass. Although presumed to be a metastatic lesion, extensive workup failed to reveal a primary tumor site. Histologic sections showed a mass composed entirely of polygonal neoplastic cells with prominent nucleoli and large hyaline cytoplasmic inclusions. The tumor cells were strongly immunoreactive with S100 protein, vimentin, and CD56, and were focally reactive with Mart-1. Tumor cells were negative for Melan-A, tyrosinase, HMB-45, AE1/AE3, cytokeratin (CK) 7, CK8/ 18, CK20, CK903, CAM 5.2, epithelial membrane antigen, smooth muscle actin, desmin, leukocyte common antigen, Bcl-2, CD3, CD20, CD30, CD138, kappa and lambda light chains, CD68, CD34, factor VIII, synaptophysin, and glial fibrillary acidic protein. Electron microscopy showed cytoplasmic whorls of intermediate filaments containing entrapped rough endoplasmic reticulum, mitochondria, and lipid. Recognition of this rare variant of malignant melanoma is important in the evaluation of tumors with rhabdoid morphology.
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PMID:Malignant melanoma with a rhabdoid phenotype: histologic, immunohistochemical, and ultrastructural study of a case and review of the literature. 1516 28


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