fumarates and Melanoma

Despite emergence of new systemic therapies, metastatic melanoma remains a challenging and often fatal form of skin cancer. The renin-angiotensin system (RAS) is a major physiological regulatory pathway controlling salt-water equilibrium, intravascular volume and blood pressure. Biological effects of the RAS are mediated by the vasoactive hormone angiotensin II (AngII) via two receptor subtypes, AT1R (encoded by AGTR1) and AT2R (encoded by AGTR2). We report decreasing expression and increasing CpG island methylation of AGTR1 in metastatic versus primary melanoma and detection in serum of methylated genomic DNA from the AGTR1 CpG island in metastatic melanoma implying that AGTR1 encodes a tumour suppressor function in melanoma. Consistent with this hypothesis, antagonism of AT1R using losartan or shRNA-mediated knockdown in melanoma cell lines expressing AGTR1 resulted in acquisition of the ability to proliferate in serum-free conditions. Conversely, ectopic expression of AGTR1 in cell lines lacking endogenous expression inhibits proliferation irrespective of the presence of AngII implying a ligand-independent suppressor function for AT1R. Treatment of melanoma cell lines expressing endogenous AT2R with either AngII or the AT2R-selective agonist Y6AII induces proliferation in serum-free conditions whereas the AT2R-specific antagonists PD123319 and EMA401 inhibit melanoma growth and angiogenesis and potentiate inhibitors of BRAF and MEK in cells with BRAF V600 mutations. Our results demonstrate that the RAS has both oncogenic and tumour suppressor functions in melanoma. Pharmacological inhibition of AT2R may provide therapeutic opportunities in melanomas expressing this receptor and AGTR1 CpG island methylation in serum may serve as a novel biomarker of metastatic melanoma.

Topics: Amides; Angiotensin II; Angiotensin-Converting Enzyme Inhibitors; Animals; Antihypertensive Agents; Cell Line, Tumor; Cell Proliferation; Cells, Cultured; DNA Methylation; Embryo, Nonmammalian; Fumarates; Humans; Imidazoles; Melanoma; Molecular Targeted Therapy; Neoplasm Metastasis; Pyridines; Receptor, Angiotensin, Type 1; Receptor, Angiotensin, Type 2; Renin-Angiotensin System; Xenograft Model Antitumor Assays; Zebrafish

The antitumor agent lonidamine (LND; 1-(2,4-dichlorobenzyl)-1H-indazole-3-carboxylic acid) is known to interfere with energy-yielding processes in cancer cells. However, the effect of LND on central energy metabolism has never been fully characterized. In this study, we report that a significant amount of succinate is accumulated in LND-treated cells. LND inhibits the formation of fumarate and malate and suppresses succinate-induced respiration of isolated mitochondria. Utilizing biochemical assays, we determined that LND inhibits the succinate-ubiquinone reductase activity of respiratory complex II without fully blocking succinate dehydrogenase activity. LND also induces cellular reactive oxygen species through complex II, which reduced the viability of the DB-1 melanoma cell line. The ability of LND to promote cell death was potentiated by its suppression of the pentose phosphate pathway, which resulted in inhibition of NADPH and glutathione generation. Using stable isotope tracers in combination with isotopologue analysis, we showed that LND increased glutaminolysis but decreased reductive carboxylation of glutamine-derived α-ketoglutarate. Our findings on the previously uncharacterized effects of LND may provide potential combinational therapeutic approaches for targeting cancer metabolism.

Topics: Antineoplastic Agents; Cell Death; Cell Line, Tumor; Citric Acid Cycle; Diacetyl; Electron Transport Complex II; Fumarates; Glutamine; Glutathione; Humans; Indazoles; Malates; Melanoma; Metabolic Flux Analysis; Mitochondria; Models, Biological; NADP; Naphthalenes; Oxidation-Reduction; Pentose Phosphate Pathway; Reactive Oxygen Species; Succinic Acid

Psoriasis is today generally considered a systemic disease. Systemic therapies are used frequently. In Germany fumaric acid esters - FAE (Fumaderm(®) ) - are employed in more than 50 % of the patients requiring such therapy. We report for the first time the development of melanoma in two patients during their treatment with FAE. The logical question is - are the tumors coincidental or might they be treatment-related? Further investigations of pathways and immunologic effects as well as careful reports of side effects are necessary to estimate the risks of malignancy of FAE.

Topics: Aged; Dermatologic Agents; Fumarates; Humans; Male; Melanoma; Middle Aged; Risk Assessment; Risk Factors; Skin Neoplasms

Dimethylfumarate (DMF) has been shown to reduce melanoma growth and metastasis in animal models. We addressed the question of whether DMF is as effective in its antitumor activity as the US Food and Drug Administration-approved alkylating agent dacarbazine (DTIC). We also tested the possibility of an improved antitumoral effect when both therapeutics were used together. Using our severe combined immunodeficiency (SCID) mouse model, in which xenografted human melanoma cells metastasize from primary skin sites to sentinel nodes, we show that these treatments, alone or in combination, reduce tumor growth at primary sites. Our main finding was that metastasis to sentinel nodes is significantly delayed only in mice treated with a combination of DTIC and DMF. Subsequent experiments were able to show that a combination of DTIC/DMF significantly reduced lymph vessel density in primary tumors as examined by real-time PCR and immunohistochemistry. In addition, DTIC/DMF treatment significantly impaired melanoma cell migration in vitro. In vivo, DTIC/DMF therapy significantly reduced mRNA expression and protein concentration of the promigratory chemokines CXCL2 and CXCL11. In addition, our data suggest that this xenotransplantation model is suitable for preclinical testing of various combinations of antimelanoma agents.

Topics: Animals; Antineoplastic Agents, Alkylating; Cell Line, Tumor; Cell Movement; Chemokine CXCL11; Chemokine CXCL2; Dacarbazine; Dermatologic Agents; Dimethyl Fumarate; Drug Therapy, Combination; Fumarates; Humans; Lymphatic Metastasis; Lymphatic Vessels; Melanoma; Mice; Mice, SCID; RNA, Messenger; Sentinel Lymph Node Biopsy; Skin Neoplasms; Xenograft Model Antitumor Assays

NF-kappaB acts as a signal transducer during tumor progression, cell invasion, and metastasis. Dimethylfumarate (DMF) is reported to inhibit tumor necrosis factor-alpha-induced nuclear entry of NF-kappaB/p65. However, only a few reports suggest that DMF inhibits tumor metastasis; also the molecular mechanisms underlying the inhibition of metastasis are poorly understood. We investigated the inhibition of tumor invasion and metastasis by DMF in a melanoma cell line, B16BL6. DMF inhibited B16BL6 cell invasion and metastasis by suppressing the expression and activities of MMPs. DMF also inhibited the nuclear entry of NF-kappaB/p65, thus inhibiting B16BL6 cell invasion and metastasis. These results suggest that DMF is potentially useful as an anti-metastatic agent for the treatment of malignant melanoma.

Topics: Animals; Cell Line, Tumor; Cell Movement; Dimethyl Fumarate; Extracellular Signal-Regulated MAP Kinases; Female; Fumarates; Immunosuppressive Agents; Matrix Metalloproteinase Inhibitors; Melanoma; Melanoma, Experimental; Mice; Mice, Inbred C57BL; Neoplasm Invasiveness; NF-kappa B; Skin Neoplasms; Transcription Factor RelA

Dimethylfumarate (DMF) inhibits signals transmitted by Rel proteins and is used for the treatment of inflammatory skin diseases such as psoriasis, but potential effects of DMF on tumor progression have yet not been analyzed. We show that DMF reduced melanoma growth and metastasis in severe combined immunodeficient mouse models. To identify targets of DMF action, we analyzed mRNA expression in DMF-treated melanomas by gene chip arrays. Using BiblioSphere software for data analysis, significantly regulated genes were mapped to Gene Ontology terms cell death, cell growth, and cell cycle. Indeed, we found that DMF inhibited proliferation of human melanoma cells A375 and M24met in vitro. The cell cycle was arrested at the G(2)-M boundary. Moreover, DMF was proapoptotic, as shown by cell cycle analysis and by Annexin V and Apo2.7 staining. These results were confirmed in vivo. DMF reduced proliferation rates of tumor cells as assessed by Ki-67 immunostaining and increased apoptosis as assessed by terminal deoxyribonucleotidyl transferase-mediated dUTP nick end labeling staining. In conclusion, DMF is antiproliferative and proapoptotic and reduces melanoma growth and metastasis in animal models.

Topics: Animals; Cell Cycle; Cell Division; Cell Line, Tumor; Dimethyl Fumarate; Female; Fumarates; Humans; Lymphatic Metastasis; Melanoma; Mice; Mice, Inbred C57BL; Neoplasm Metastasis; Radiation-Sensitizing Agents; Transplantation, Heterologous

Topics: Animals; Catechol Oxidase; Chromatography; Dihydroxyphenylalanine; Fumarates; Hydrogen-Ion Concentration; Melanoma; Methods; Mice; Monophenol Monooxygenase; Neoplasm Transplantation; Neoplasms, Experimental; Oxidation-Reduction; Radioisotopes; Spectrophotometry; Time Factors; Tyrosine

Topics: Amines; Animals; Biphenyl Compounds; Carbamates; Dihydroxyphenylalanine; Endoplasmic Reticulum; Fumarates; Golgi Apparatus; Hydrogen Peroxide; Melanins; Melanoma; Mice; Microscopy, Electron; Neoplasm Transplantation; Neoplasms, Experimental; Oxidation-Reduction; Peroxidases; Thiocarbamates; Tyrosine