Faculty Bibliography

PURPOSE: Current standard chemotherapeutic regimens for malignant melanoma are unsatisfactory. Although in vitro studies of arsenic trioxide (ATO) have demonstrated promise against melanoma, recent phase II clinical trials have failed to show any significant clinical benefit when used as a single agent. To enhance the efficacy of ATO in the treatment of melanoma, we sought to identify compounds that potentiate the cytotoxic effects of ATO in melanoma cells. Through a screen of 2,000 marketed drugs and naturally occurring compounds, a variety of antibiotic inhibitors of mitochondrial protein translation were identified. METHODS: The mechanism of action for the most effective agent identified, thiostrepton, was examined in a panel of melanoma cells. Effects of combinatorial ATO and thiostrepton treatment on cytotoxicity, apoptosis, mitochondrial protein content, and reactive oxygen species (ROS) were assessed. RESULTS: Thiostrepton (1 microM) sensitized three out of five melanoma cell lines to ATO-mediated growth inhibition. Treatment with thiostrepton resulted in reduced levels of the mitochondrial-encoded protein cytochrome oxidase I (COX1). Exposure to thiostrepton in combination with ATO resulted in increased levels of cleaved poly (ADP-ribose) polymerase and cellular ROS. The growth inhibitory and pro-apototic effects of addition of the ATO/thiostrepton combination were reversed by the free radical scavenger N-acetyl-L-cysteine. CONCLUSIONS: Our data suggest that thiostrepton enhances the cytotoxic effects of ATO through a ROS-dependent mechanism. Co-administration of oxidative stress-inducing drugs such as thiostrepton in order to enhance the efficacy of ATO in the treatment of melanoma warrants further investigation

A series of quinolines, including chloroquine and quinine, were identified as potent pigmentation inhibitors through screening a compound library in murine melanocytes. Structure-activity relationship analysis indicated that 4-substituted amino groups with a tertiary amine side chain, such as chloroquine, were associated with robust inhibitory activity. In contrast to many previously identified pigmentation inhibitors, these newly identified inhibitors had no effect on either the level or the enzymatic activity of tyrosinase, the rate-limiting enzyme in melanin production. Rather, our results showed that these quinolines inhibited melanogenesis by disrupting the intracellular trafficking of tyrosinase-related proteins and lysosome-associated membrane protein 1 (Lamp-1). In treated melanocytes, tyrosinase and tyrosinase-related protein 1 accumulated in Lamp-1-positive perinuclear organelles instead of melanosomes, thus preventing melanogenesis. The depigmenting abilities of chloroquine and quinine salicylate were assessed in a human skin equivalent model (MelanoDerm). Both compounds were considerably more effective than arbutin, a widely used lightening agent. Our results indicate that quinolines may be useful agents for 'cosmeceutical' skin lightening and treatment of hyperpigmentation disorders

Most metastatic melanoma patients fail to respond to available therapy, underscoring the need for novel approaches to identify new effective treatments. In this study, we screened 2,000 compounds from the Spectrum Library at a concentration of 1 micromol/L using two chemoresistant melanoma cell lines (M-14 and SK-Mel-19) and a spontaneously immortalized, nontumorigenic melanocyte cell line (melan-a). We identified 10 compounds that inhibited the growth of the melanoma cells yet were largely nontoxic to melanocytes. Strikingly, 4 of the 10 compounds (mebendazole, albendazole, fenbendazole, and oxybendazole) are benzimidazoles, a class of structurally related, tubulin-disrupting drugs. Mebendazole was prioritized to further characterize its mechanism of melanoma growth inhibition based on its favorable pharmacokinetic profile. Our data reveal that mebendazole inhibits melanoma growth with an average IC(50) of 0.32 micromol/L and preferentially induces apoptosis in melanoma cells compared with melanocytes. The intrinsic apoptotic response is mediated through phosphorylation of Bcl-2, which occurs rapidly after treatment with mebendazole in melanoma cells but not in melanocytes. Phosphorylation of Bcl-2 in melanoma cells prevents its interaction with proapoptotic Bax, thereby promoting apoptosis. We further show that mebendazole-resistant melanocytes can be sensitized through reduction of Bcl-2 protein levels, showing the essential role of Bcl-2 in the cellular response to mebendazole-mediated tubulin disruption. Our results suggest that this screening approach is useful for identifying agents that show promise in the treatment of even chemoresistant melanoma and identifies mebendazole as a potent, melanoma-specific cytotoxic agent

Skin cancer is one of the most preventable groups of malignancies; however, skin cancer incidence continues to rise in the United States. The relationship between skin cancer and ultraviolet (UV) radiation is well known. Many interventions to prevent skin cancer by reducing exposure to UV radiation have been employed throughout the United States. Studies show an increase in knowledge and awareness regarding sun exposure and skin cancer. Unfortunately, sun protection interventions are slow at effecting behavioral change. In this review, we examine current barriers facing youth today in regards to sun protection practices, appropriate age groups to target for intervention, proposed methods of sun protection, the influence of role models in changing sun protective behavior, the stages of behavioral change, and characteristics and techniques of sun protection programs that can not only increase knowledge but actually elicit changes in sun protection behavior

Aplasia cutis congenita (ACC) in a symmetric, stellate pattern on the trunk or extremities is classically associated with a fetus papyraceus. We report symmetric truncal ACC in a neonate born of a sextuplet pregnancy that had been reduced to twins. This case highlights truncal ACC as a consequence of modern reproductive medicine

Pegylated liposomal doxorubicin (PLD, Doxil, Caelyx) is widely used for the treatment of ovarian cancer. It is a stable formulation encapsulating doxorubicin in a 'Stealth' (i.e., pegylated) liposome with a half-life of about 72 hours. This drastically altered pharmacology confers on it a considerably lower risk of cardiotoxicity, no acute emesis, and near absence of alopecia or problems with extravasation necrosis. On the other hand, PLD's dose-limiting toxicity is cutaneous. Since the original phase I report, cutaneous toxicities reported with PLD fall into four common categories: the well known hand-foot syndrome (also called palmoplantar erythrodysesthesia, or PPE), a diffuse follicular rash, intertrigo-like eruption, and hyperpigmentation including melanotic macules

There is a continual need for compounds that effectively modulate melanin synthesis. To identify novel pigmentation modulators and their cellular targets, chemical genetic screenings were performed with triazine-based combinatorial libraries that include various linkers as intrinsic components of the small molecules in the library. The linker provides a ready means of attachment to beads, eliminating several common time-consuming downstream steps in the isolation of cellular targets for the small molecules of interest. Twelve compounds were identified as novel pigmentation modulators from various screenings performed in normal and albino murine melanocytes and zebrafish. Target identification by affinity chromatography revealed unexpected roles for prohibitin and mitochondrial F1F0-adenotriphosphatase in the regulation of mammalian pigmentation. The identification of prohibitin, a "scaffold protein", as a propigmentation effector represents a novel mechanism by which propigmentary signals are transduced. Results from our screenings provide potential active agents and targets for the medical and aesthetic treatment of disorders of pigmentation.

BACKGROUND: Reports of successful treatment of atopic dermatitis (AD) with mycophenolate mofetil (MMF) have thus far been limited to adults. Considering that the condition typically develops during childhood and is most active during this period, MMF would represent a valuable addition to the therapeutic armamentarium for paediatric AD. OBJECTIVES: To evaluate the safety and efficacy of MMF in the treatment of severe childhood AD. METHODS: A retrospective analysis was performed of all children treated with MMF as systemic monotherapy for severe, recalcitrant AD between August 2003 and August 2006 at New York University Medical Center. Fourteen patients meeting these criteria were identified. RESULTS: Four patients (29%) achieved complete clearance, four (29%) had > 90% improvement (almost complete), five (35%) had 60-90% improvement and one (7%) failed to respond. Initial responses occurred within 8 weeks (mean 4 weeks), and maximal effects were attained after 8-12 weeks (mean 9 weeks) at MMF doses of 40-50 mg kg(-1) daily in younger children and 30-40 mg kg(-1) daily in adolescents. The medication was well tolerated in all patients, with no infectious complications or development of leucopenia, anaemia, thrombocytopenia or elevated aminotransferases. CONCLUSIONS: This retrospective case series demonstrates that MMF can be a safe and effective treatment for severe, refractory AD in children. MMF represents a promising therapeutic alternative to traditional systemic immunosuppressive agents with less favourable side-effect profiles, and prospective controlled studies are warranted, further to assess its benefits in paediatric AD