Objetivos: evaluar la eficacia de la braquiterapia en los ojos afectos de melanoma de coroides y cuerpo ciliar tratados con placas radioactivas de I 125 y Ru 106.Material y métodos: presentamos 84 casos de ojos con melanomas de úvea diagnosticados mediante examen clínico, en pacientes sin metástasis a los cuales se les ofreció tratamiento mediante braquiterapia ( I 125 / Ru 106 ) durante el periodo comprendido entre octubre de 1993 y abril del 2000, con un seguimiento mínimo de 12 meses. En 74 casos se utilizaron placas de Ru 106 y en 10 de I 125 . La altura inicial media eran 6,78 mm.Resultados: usando el Kaplan-Meier, la visión final fue escasa ( ≤ 0,10 ) en el 60,7 % de los ojos. Las complicaciones en relación al tratamiento fueron: 20,3 % retinopatía, 14,3 % neuropatía, 14,3 % catarata y 13,1 % hemorragia vítrea. Las complicaciones fueron más frecuentes en mujeres y en los tumores localizados a nivel de cuerpo ciliar y yuxtapapilares. La enucleación fue necesaria en 6 casos.Conclusiones: las placas de braquiterapia proporcionan control tumoral en la mayoría de los pacientes con melanomas de úvea seleccionados (> 3 mm y ≤ 9,3 altura ) a 1383 días, que de otro modo hubiesen sido enucleados. Un gran tamaño tumoral, hallazgos asociados y las complicaciones por la radiación son causa de la mala visión en la mayoría de los pacientes. / Objective: to assess efficiency of brachitherapy in eyes with choroidal melanoma and ciliar body melanoma treated with I125 and Ru106 radiactive plaques. Patients and Methods: 84 patients with uveal melanomas were diagnosed by clinical examination, found to be negative for metastasic disease and offered I 125 or Ru 106 radioactive plaque treatment. From octuber 1993 to april 2000, 74 cases were treated with Ru 106 and 10 cases with I 125, with a minimal follow up 12 months. The inicial high was 6,78 mm.Results: Using Kaplan-Meier estimates, final visual acuity was poor in 60,7 % at 1383 days ( 20/200 or worse ). Treatment-related complications included retinopathy ( 20,3 %), neuropathy ( 14,3 %), cataract ( 14,3 %) and vitreous hemorrhage ( 13,1 % ). Risk factors for complications included sex, proximity to the optic nerve and ciliary body involment. Enucleation was necessary in 6 cases.Conclusions: plaque radiotherapy provided tumor control a 1383 days in most patients with selected uveal melanomas ( > 3 mm and ≤ 9,3 thick ) that otherwise would have been managed with enucleation. The large intraocular mass and associated features and radiation complications led to poor visual acuity in most patients.

Magnetic resonance imaging (MRI) is the leading imaging technique for disease diagnostics. MRI contrast agents facilitate MRI technique to obtain tissue-specific image with improved sensitivity and signal-to-noise ratio. However, the applications of current MRI contrast agents are hampered by their uncontrolled blood circulation time, low relaxivity, and low specificity. To address such need, I have developed a series of analitical methods to determine and evaluate the strong metal binding affinity and metal selectivity of developed protein-based contrast agents (ProCAs). In addition, we have successed designed contrast agents ProCA3 series based on key determinats for metal binding sites and relaxivity. We have dementrated that one of the ProCA3 variants, ProCA32, has a high Gd3+ affinity less than 10-21 M and high metal selectivity with relxivity of more than 30 mM-1s-1 per Gd and 60 mM-1s-1 per particle. Moreover, we have demonstrated that ProCA3 variants have proper blood circulation time, high relaxivity, high metal selectivity and low toxicity, which facilitate MR imaging of multiple organs, such as liver, kidney, and blood vessels, as well as tumors. ProCA32 is also able to image liver metastases a tumor size less than 0.25 mm, which is more than fourty times more sensitive than that of clinical diagnostics of liver metastases using MRI and our developed methodology. We have further created ProCA3 variants with targeting peptide moieties such as ProCA3.bomb or ProCA3.affi to against cancer biomarkers such as GRPR and HER2 with capability to imaging tumor biomarker expressions in vivo at molecular level. We have shown that ProCA3 has an excellent safety profile and pharmacokinetics for MRI in animals. With our additional effect in protein expression, modification, and scale up production of these developed protein contrast agents, ProCA3 is expected to be a promising MRI contrast for the diagnostics for disease, such as metastatic tumor and blood vessel abnormalities, and tumor biomarkers.

Despite the development of novel target therapy drugs in recent years, metastatic cancer remains refractory to current cancer therapies and accounts for the majority of cancer mortalities worldwide. Metastasis consists of multiple steps including angiogenesis, extravasion, escape from immune surveillance, adhesion, and clonal expansion in different organs that a systemic therapy is required for effective control of metastasis. The pro-inflammatory nuclear factor kappa B (NF£eB) pathway plays an important role during each of these metastatic events and constitutes an excellent target for metastasis control. Stress hormone pro-opiomelanocortin (POMC) and its derived neuropeptides including corticotrophin (ACTH), £\-, £]-, and £^-melanocyte¡Vstimulating hormone (£\-, £]-, and £^-MSH), £]-endorphin are potent inhibitors of NF£eB pathway. Other than the central regulation of stress response and energy homeostasis, POMC also regulates the skin pigmentation, inflammatory processes, and immune reactions in the peripheral system. Since adenovirus¡Vmediated POMC gene delivery leads to hepatic POMC expression, it seems plausible that POMC gene therapy may elicit systemic production of anti-inflammatory POMC-derived peptides and hold promises for control of primary and metastatic cancers. In B16-F10 melanoma models, POMC gene delivery elevated the circulating ACTH levels for more than 8 weeks and suppressed the growth of established melanoma, thereby prolonging the life span of tumor-bearing mice. Moreover, combination of POMC therapy with cisplatin further enhances the survival outcome. Subsequent analysis reveals that POMC gene therapy inhibits the growth and metastasis of melanoma through apoptosis, angiogenesis inhibition, and modulation of epithelial-mesenchymal transition. Besides, £\-MSH/melanortin-1 receptor (MC-1R) pathway is involved in the POMC-mediated melanoma suppression. To investigate whether POMC therapy could be applied to other types of tumor, we evaluated the therapeutic efficacy of POMC gene therapy in Lewis lung carcinoma (LLC) cells which lack MC-1R. Interestingly, POMC gene delivery effectively inhibited the proliferation and colony formation of LLC cells in vitro and the growth of established LLC in mice. Histological analysis indicated that POMC gene delivery attenuated LLC through proliferation inhibition, apoptosis induction, and angiogenesis blockade. Moreover, POMC gene delivery perturbed £]-catenin signaling by reducing protein levels of £]-catenin and its downstream proto-oncogenes, including cyclin D1 and c-myc. These results support the existence of an MC-1R-independent pathway for POMC gene therapy and expand the therapeutic spectrum of POMC therapy for multiple types of cancer. To elucidate the role of host immunity in anti-neoplastic mechanism underlying POMC therapy, we compared the treatment efficacy of POMC gene therapy for B16-F10 melanoma between severe combined immune-deficient (SCID) and immune-competent C57BL/6 mice, and found similar extent of tumor suppression in both strains of mice. In addition, POMC gene therapy reduced the spleen weight and the number of circulating lymphocytes in B6 mice. These findings suggest that POMC therapy was not dependent on host immunity, yet instead induced immune suppression of animals through ACTH/cortisol production. To minimize such side effect of POMC therapy, we generated a series of adenovirus vectors encoding POMC with mutations in ACTH domain (ACTH-K15A/R17A), which fails to stimulate cortisol synthesis in vitro and in vivo. Gene delivery of ACTH (K15A/R17A) remained capable of suppressing the primary and metastatic melanoma, but had no effect on immune functions in mice. In conclusion, we have characterized the anti-neoplastic function and mechanism of POMC therapy for cancer. Furthermore, we have developed improved POMC gene vectors to minimize its adverse effect for future cancer therapy.

Cutaneous malignant melanoma is the fastest increasing malignancy in humans. Hepatoma-derived growth factor (HDGF) is a novel growth factor identified from human hepatoma cell line. HDGF overexpression is correlated with poor prognosis in various types of cancer including melanoma. However, the underlying mechanism of HDGF overexpression during melanoma carcinogenesis remains unclear. In this study, adding exogenous HDGF stimulated the invasion and colonies formation of B16-F10 melanoma cells. Adenovirus vectors encoding HDGF and HDGF-RNAi were generated and characterized to up- and down-regulated HDGF expression in B16-F10 melanoma cells. It was found that HDGF overexpression stimulated the proliferation, invasiveness, anchorage-independent growth of B16-F10 melanoma cells whereas HDGF knockdown exerted opposite effects. In lung-metastasis model, intravenous injection of HDGF-overexpressing melanoma cells resulted in increased metastasis while HDGF-downregulated melanoma cells caused decreased metastasis. Similarly, in primary melanoma model, subcutaneous injection of HDGF-overexpressing melanoma cells enhanced while HDGF-downregulated melanoma cells reduced the tumor burden in mice. Histological analysis revealed increased tumor proliferation and neovascularization with concomitant reduction of apoptosis in HDGF-overexpressing melanoma. Moreover, HDGF-overexpressing melanoma also exhibited enhanced propensity to metastasize from the primary tumors to lymph node and lung. Finally, it was found that HDGF overexpression increased nuclear factor kappa B (NF£eB) activities and Akt phosphorylation up and down stream alternation like PI3K, PTEN, I£eB and it¡¦s subunit IKK£\, IKK£], IKK£^ in melanoma cells. It also found that HDGF overexpression influenced MITF and HIF1£\ in melanoma after gene delivery. HDGF also altered EMT changes like E,N-cadherin, vimentin, and £],£^-catenin. The present study provides conclusive evidence that HDGF upregulation promotes the growth and metastasis of melanoma by promoting the survival and vascularization. Besides, HDGF knockdown may constitute a novel strategy for melanoma control.

Cadherin and catenin-family proteins regulate adhesion in malignant melanoma. Using AQUA (Automated Quantitative Analysis) to quantitate the levels of alpha-catenin, beta-catenin, p120-catenin, N-cadherin, E-cadherin, and P-cadherin in melanoma on tissue microarrays (TMAs), we classified 513 patients by protein expression using hierarchical clustering and regression analysis. The dendrogram supported positive correlations seen upon Spearman rho analysis of P-cadherin and beta-catenin (r=0.5238, p<0.0001) and negative, weak association of N-cadherin with other markers. Patients with high expression of N-cadherin had the highest 20-year survival rate (p=0.0003). Our adherens protein molecular classification of melanoma defines at least two distinctive sub-populations of melanoma patients, those with high expression of N-cadherin and those with low expression who have decreased survival. These findings extend previous cDNA array-based findings of an epithelioid class and neural crest class of melanomas.

Melanoma manifests itself from the malignant transformation of melanocytes and represents the deadliest form of skin cancer, being responsible for the disproportionate majority of all skin cancer deaths. The 2002 discovery that 50% of all melanoma patients possess activating BRAF mutations ignited a significant paradigm shift in the way the melanoma field approached research and how patients were treated [1]. The era of targeted therapy had begun and with it came successful targeted BRAF inhibitor therapy regimens, which have accomplished improved clinical benefit (response rate, progression free survival, and overall survival) compared with treatment with chemotherapy in three phase III clinical trials [2]. Although there has been much success in the subgroup of patients whose melanomas harbor activating BRAF mutations, approximately 50% of all melanoma patients do not harbor BRAF mutations. This subgroup of melanoma is composed of ~15-20% of all patients with NRAS mutations and another ~25-30% of patients with neither BRAF nor NRAS mutations. Successful targeted treatment strategies are currently lacking for this subgroup of BRAF-wild type melanomas and therefore novel targeted therapeutic modalities are urgently needed. The work described in this dissertation sheds light on potential approaches for the treatment of BRAF wild type melanoma and will be split into three separate strategies. The first will focus upon the treatment of melanomas without BRAF or NRAS mutations (BRAF/NRAS wild type melanoma) and will expand upon a clinical observation where two melanoma patients were treated with an experimental combination of carboplatin and paclitaxel, with the addition of the AKT inhibitor MK-2206. We demonstrate that the inhibition of AKT significantly enhances the efficacy of chemotherapy in a reactive oxygen species (ROS) mediated fashion, and an induction of autophagy plays a cyto-protective role. The second story focuses upon the treatment of NRAS mutant melanomas by investigating resistance mechanisms to MEK inhibitor treatment. We discovered a MEKi-mediated induction of receptor tyrosine kinase (RTK) signaling to serve as a significant mechanism of escape for NRAS mutant melanomas treated chronically with the MEK inhibitor AZD6244, as well as the recently U.S. Food and Drug Administration (FDA) approved MEK inhibitor trametinib. Novel targeted therapy combinations were then added to overcome the escape from MEK inhibitor therapy. Co-targeting of the receptor tyrosine kinases AXL, PDGFR-β and c-MET with a pan-RTK inhibitor, as well as the mitogen-activated protein kinase (MAPK) pathway with a MEK inhibitor greatly enhanced treatment-induced apoptosis and inhibition of proliferation. The final strategy builds upon the observation that single agent MEK-inhibition is largely ineffective in the treatment of NRAS mutant melanomas. A recovery of MAPK pathway activity in response to MEK inhibition was established to play a significant role in escape of NRAS mutant cells from cell cycle arrest and apoptosis. The combination of a MEK inhibitor with the novel ERK inhibitor VTX-11e prevents the onset of resistant clones and enhances cytotoxicity of the NRAS mutant melanoma cells. This body of work establishes original targeted therapy combinations for the treatment of both NRAS mutant melanomas and BRAF/NRAS wild type melanomas. We propose future clinical investigation with these strategies in the treatment of BRAF wild type melanoma patients in hopes to further extend overall survival.

BRAF(V600E), the most commonly mutated oncogene in melanoma, is found in about half of patients. By hyperactivating the MAPK pathway, this mutation promotes cell growth and proliferation. Melanocytic BRAF(V600E) alone, however, is insufficient to cause melanoma and rather promotes the development of benign nevi (moles). The goal of our initial studies was to better understand how genetic and environmental risk factors interact with the BRAF(V600E) oncogene to induce melanoma. The two most prominent risk factors for melanoma development are exposure to ultraviolet (UV) radiation and pale skin pigmentation; particularly in the case of individuals with the “redhead” phenotype, who carry inactivating mutations in the MC1R G-protein coupled receptor. It has commonly been thought that redheads are at highest risk for melanoma development due to poor protection from genotoxic UV radiation from the sun. Using a melanocyte-specific, inducible Braf(V600E) mouse model, we have shown that an inactivating mutation in Mc1r which causes a redhead phenotype in mice, confers a significant UV-independent elevation in melanoma risk, relative to black and albino animals. The mechanism of accelerated UV-independent oncogenesis was found to be dependent on the synthesis of the red/yellow pheomelanin pigment. While these experiments were on-going, a novel small molecule inhibitor of the BRAF(V600E) oncogene, vemurafenib, began showing promising results in clinical trials. The observation that half of patients were experiencing significant tumor regression was unprecedented, but was soon followed by vemurafenib-resistant disease progression. Based on the fact that acquired drug resistance is a major obstacle to good therapeutic outcomes, we began investigating mechanisms of BRAF inhibitor resistance. A panel of BRAF(V600E) human melanoma cell lines that were initially sensitive to PLX4720 (a pre-clinical analog of vemurafenib), were chronically treated with the oncogenic BRAF inhibitor until resistance developed. These paired resistant and sensitive cell lines were characterized in terms of drug sensitivity and activation of cell signaling pathways. Multiple different patterns of drug resistance were found. The diversity of resistance mechanisms in these studies agrees with the diversity which others have found in the literature, suggesting that melanoma cells may be uniquely adaptable to circumventing BRAF(V600E) oncogene addiction.

Several chemically-modified analogues of α-melanotropin (α-MSH, Ac-Ser-Tyr-Ser-Met-Glu-His-Phe-Arg-Trp-Gly-Lys-Pro-Val-NH₂) were prepared by solid-phase peptide synthesis, including [Nle⁴]-α-MSH, Ac-[Nle⁴]-α-MSH₄₋₁₃-NH₂, Ac-[Nle⁴]-α-MSH₁₋₆-NH₂, Ac-α-MSH₇₋₁₀-NH₂, Ac-α-MSH₁₁₋₁₃-NH₂, Ac-[Nle⁴]-α-MSH(,4-10)-NH₂, Ac-[Nle⁴, D-Phe⁷]-α-MSH₄₋₁₀-NH₂, [Nle⁴, D-Phe⁷]-α-MSH, Ac-α-MSH₄₋₁₀-NH₂, Ac-[Tyr⁴]-α-MSH₄₋₁₀-NH₂ and [half-Cys⁴, half-Cys¹⁰]-α-MSH. The synthetic strategy involved: (1) p-methylbenzhydrylamine resin as a solid support, (2) N,N'-dicyclohexylcarbodiimide as a coupling reagent, (3) acetylation of the N-terminus and HF cleavage and deprotection (except for Nⁱ-For-Trp) of the fully assembled peptide-resin and (4) alkaline hydrolysis to deformylate Nⁱ-For-Trp. In the preparation of [half-Cys⁴, half-Cys¹⁰]-α-MSH, oxidative-cyclization provided formation of an intramolecular disulfide bridge. A comparative biological analysis in vitro of these above structural, stereoisomeric and conformationally-restricted analogues of α-MSH on several different vertebrate pigment cell systems provided the following results: (1) The [Nle⁴, D-Phe⁷]-α-MSH effected high melanotropic potency (> 60 times relative to α-MSH), ultralong biological activity and unprecedented metabolic stability. (2) Utilizing [Nle⁴, D-Phe⁷]-α-MSH as a molecular probe, two melanotropic receptor types were demonstrated which were mechanistically different in terms of calcium dependency and apparent hormone-receptor complex reversibility. (3) The Ac-[Nle⁴, D-Phe⁷]-α-MSH₄₋₁₀-NH₂ was a highly potent active site (Met-Glu-His-Phe-Arg-Trp-Gly) analogue of α-MSH (ranging from 0.2- to 10-times relative to α-MSH) without the ultralong melanotropic activity possessed by the parent stereostructural tridecapeptide. (4) The [half-Cys4, half-Cys10]-α-MSH exhibited superpotency on frog (Rana pipiens) melanophores (≥ 10,000 times relative to α-MSH), and provided experimental evidence that a pseudocyclic conformation of the native hormone containing a β-turn structural requirement at His-Phe-Arg-Trp might be related to its biological activity at the pigment cell receptor. The [Nle⁴, D-Phe⁷]-α-MSH may be suitable for use as a radio-labeled tracer or drug-delivery agent for the localization or treatment of human melanoma in vivo.

Cumulative evidence suggests that redox dysregulation in cancer cells represents a chemical vulnerability that can be targeted by pharmacological modulation of cellular oxidative stress. According to this emerging mechanism, pharmacological prooxidants may induce deviations from redox homeostasis causing cytotoxicity confined to malignant cells already at a high set point of constitutive oxidative stress leading to functional impairment, cell cycle arrest, and cell death. In contrast, the same prooxidant deviation from redox homeostasis is tolerated by nonmalignant cells that operate at a lower redox set point. This work focuses on experimental redox drug discovery targeting metastatic melanoma cells by pursuing the following specific aims: I. To identify drug-like lead compounds containing redox-directed pharmacophores for prooxidant intervention targeting melanoma in relevant models of the human disease. II. To investigate the molecular mechanism of action underlying antimelanoma activity of our lead compounds comprising Michael acceptors [cinnamaldehyde (CA) and 2,6-dichlorophenolindophenol (DCPIP)] and endoperoxides [dihydroartemesinin (DHA)]. III. To explore the therapeutic potential of drug-like electrophiles for non-melanoma indications including skin photoprotection and genotype-directed cancer chemotherapy. First, we have explored the possibility that prooxidant dietary constituents containing an electrophilic Michael acceptor pharmacophore may display chemotherapeutic activity. Focusing on the cinnamon-derived Michael acceptor CA we have demonstrated significant anti-melanoma activity of this dietary prooxidant observed in vitro and in vivo. Second, we have demonstrated that the synthetic quinoneimine and redox dye DCPIP targets human melanoma cells in vitro and in vivo. DCPIP-apoptogenicity observed in the human melanoma cell lines A375 and G361 was inversely correlated with NAD(P)H:quinone oxidoreductase (NQO1) expression levels. Efficacy against tumors with low NQO1 enzymatic activity including those displaying the human homozygous NQO1*2 missense genotype suggests feasibility of DCPIP-based genotype-directed redox intervention. Third, we demonstrated that the endoperoxide-based antimalarial DHA may serve as an experimental redox chemotherapeutic that selectively induces iron-dependent melanoma cell apoptosis without compromising viability of primary human melanocytes. Given the causative role of redox dysregulation in melanoma and the shortage of efficacious agents currently available, it seems that the emerging therapeutic potential of redox-directed chemotherapeutics for melanoma intervention deserves further evaluation.

Konstitutiv aktivierte Signalwege sind verantwortlich für die malignen Veränderungen in Melanozyten, die zur Entstehung des Melanoms beitragen. Im Mittelpunkt dieser Veränderungen stehen der PI3Kinase-AKT-Signalweg und der MAPK-ERK-Signalweg als wichtige Schlüsselwege in der Zellzykluskontrolle. Daher zielen viele neue Therapieversuche im Kampf gegen das Melanom auf die Kontrolle und Regulation dieser Wege. In dieser vorliegenden Arbeit wurden erstmals die Effekte eines neuen PI3K-Inhibitors, BAY-80-6946, und Wortmannin alleine und in Kombinationsbehandlungen mit den MEK1/2-Inhibitoren PD98059 und U0126 in vitro und in vivo untersucht. Zunächst wurden humane Melanomzellen auf konstitutiv aktivierte Signalwege in vitro per Western Blot untersucht und ihre Wachstumsraten im Mausmodell ermittelt. Die humane Melanomzelllinie LOX zeigte eine hohe konstitutive Expression von aktiviertem AKT und ERK, während A375 nur eine geringe Aktivität dieser beiden Signalwege aufwies. Dennoch besaßen diese beiden Zelllinien ein großes Wachstumspotential im Mausmodell im Vergleich zu anderen getesteten Zelllinien. A375 und LOX wurden in Zellkulturexperimenten mit den PI3Kinase-Inhibitoren Bay-80-6946 und Wortmannin sowie den MEK1/2-Inhibitoren PD98059 und U0126 behandelt und Tumor-relevante Zellfunktionen wie Proliferation und Apoptose gemessen. Die Zelllinien zeigten ein unterschiedliches Ansprechen auf die verschiedenen Inhibitoren und keine der Behandlungen wies eine zufriedenstellendes Ergebnis hinsichtlich der Anti-tumoralen Funktion auf. Bei dualer PI3Kinase- und MEK1/2-Hemmung zeigten sich jedoch deutliche synergistische Effekte, so dass diese Behandlungsform einen vielversprechenden Ansatz im Kampf gegen das Melanom darstellt.