Chemoprevention of melanoma: an unexplored strategy

Phytoconstituent-derived zingerone nanoparticles disrupt the cell adhesion mechanism and suppress cell motility in melanoma B16F10 cells

Combining phytochemicals and nanotechnology to improve the unfavorable innate properties of phytochemicals and develop them into potent nanomedicines to enhance antitumor efficacy has become a novel strategy for cancer chemoprevention. Melanoma is the most aggressive, metastatic, and deadly disease of the primary cutaneous neoplasms. In this study, we fabricated phytoconstituent-derived zingerone nanoparticles (NPs) and validated their effects on cell adhesion and motility in melanoma B16F10 cells. Our data indicated that zingerone NPs significantly induced cytotoxicity and anti-colony formation and inhibited cell migration and invasion. Moreover, zingerone NPs dramatically interfered with the cytoskeletal reorganization and markedly delayed the period of cell adhesion. Our results also revealed that zingerone NPs-mediated downregulation of MMPs (matrix metalloproteinases) activity is associated with inhibiting cell adhesion and motility. We further evaluated the effects of zingerone NPs on Src/FAK /Paxillin signaling, our data showed that zingerone NPs significantly inhibited the protein activities of Src, FAK, and Paxillin, indicating that they play important roles in zingerone NP-mediated anti-motility and anti-invasion in melanoma cells. Accordingly, the phytoconstituent-zingerone NPs can strengthen the inhibition of tumor growth, invasion, and metastasis in malignant melanoma. Altogether, these multi-pharmacological benefits of zingerone NPs will effectively achieve the purpose of melanoma prevention and invasion inhibition.

Luteolin binds Src, promotes STAT3 protein ubiquitination and exerts anti-melanoma effects in cell and mouse models

Signal transducer and activator of transcription 3 (STAT3) has been proposed as a target for melanoma prevention. Luteolin, a bioactive flavonoid abundant inmedicinal herbs, has been reported to have anti-melanoma activity in vitro. However, its in vivo anti-melanoma effects and underlying mechanisms have not been fully elucidated. In this study, ten cell lines and two mouse models (B16F10 allograft and A375 xenograft models) were used for assessing the in vitro and in vivo anti-melanoma effects of luteolin. A STAT3 over-activated stable A375 cell line was used to determine the contribution of STAT3 signaling in luteolin's anti-melanoma effects. Results showed that luteolin dose-dependently reduced viability of melanoma cells. Luteolin also induced apoptosis in, and suppressed migration and invasion of, A375 and B16F10 melanoma cells. Mechanistically, luteolin inhibited phosphorylation of STAT3 and Src (an upstream kinase of STAT3), accelerated ubiquitin-proteasome pathway-mediated STAT3 degradation, and downregulated the expression of STAT3-targeted genes involved in cell survival and invasion in melanoma cells. Molecular modelling and surface plasmon resonance imaging showed that luteolin stably bound to the protein kinase domain of Src. Animal studies demonstrated that prophylactic administration of luteolin restrained melanoma growth and Src/STAT3 signaling in both A375 and B16F10 melanoma-bearing mice. Moreover, luteolin's anti-melanoma effects were diminished by STAT3 over-activation in A375 cells. Our findings indicate that luteolin inhibits STAT3 signaling by suppressing STAT3 activation and promoting STAT3 protein degradation in melanoma cells, thereby exhibiting anti-melanoma effects. This study provides further pharmacological groundwork for developing luteolin as a chemopreventive agent against melanoma.

Skin cancer, including related pathways and therapy and the role of luteolin derivatives as potential therapeutics

Cutaneous malignant melanoma is the fastest growing and the most aggressive form of skin cancer that is diagnosed. However, its incidence is relatively scarce compared to the highest mortality rate of all skin cancers. The much more common skin cancers include nonmelanoma malignant skin cancers. Moreover, over the past several decades, the frequency of all skin cancers has increased much more dynamically than that of almost any other type of cancer. Among the available therapeutic options for skin cancers, chemotherapy used immediately after the surgical intervention has been an essential element. Unfortunately, the main problem with conventional chemopreventive regimens involves the lack of response to treatment and the associated side effects. Hence, there is a need for much more effective anticancer drugs. Correspondingly, the targeted alternatives have involved phytochemicals, which are safer chemotherapeutic agents and exhibit competitive anticancer activity with high therapeutic efficacy. Among polyphenolic compounds, some flavonoids and their derivatives, which are mostly found in medicinal plants, have been demonstrated to influence the modulation of signaling pathways at each stage of the carcinogenesis process, which is also important in the context of skin cancers. Hence, this review focuses on an exhaustive overview of the therapeutic effects of luteolin and its derivatives in the treatment and prevention of skin cancers. The bioavailability and structure–activity relationships of luteolin derivatives are also discussed. This review is the first such complete account of all of the scientific reports concerning this particular group of natural compounds that target a specific area of neoplastic diseases.

Use of Nanoparticles in Delivery of Nucleic Acids for Melanoma Treatment

Melanoma accounts for 4% of all skin cancer malignancies, with only 14% of diagnosed patients surviving for more than 5 years after diagnosis. Until now, there is no clear understanding of the detailed molecular contributors of melanoma pathogenesis. Accordingly, more research is needed to understand melanoma development and prognosis.All the treatment approaches that are currently applied have several significant limitations that prevent effective use in melanoma. One major limitation in the treatment of cancer is the acquisition of multidrug resistance (MDR). The MDR results in significant treatment failure and poor clinical outcomes in several cancers, including skin cancer. Treatment of melanoma is especially retarded by MDR. Despite the current advances in targeted and immune-mediated therapy, treatment arms of melanoma are severely limited and stand as a significant clinical challenge. Further, the poor pharmacokinetic profile of currently used chemotherapeutic agents is another reason for treatment failure. Therefore, more research is needed to develop novel drugs and carrier tools for more effective and targeted treatment.Nucleic acid therapy is based on nucleic acids or chemical compounds that are closely related, such as antisense oligonucleotides, aptamers, and small-interfering RNAs that are usually used in situations when a specific gene implicated in a disorder is deemed a therapeutically beneficial target for inhibition. However, the proper application for nucleic acid therapies is hampered by the development of an effective delivery system that can maintain their stability in the systemic circulation and enhance their uptake by the target cells. In this chapter, the prognosis of the different types of melanoma along with the currently used medications is highlighted, and the different types of nucleic acids along with the currently available nanoparticle systems for delivering these nucleic acids into melanoma cells are discussed. We also discuss recently conducted research on the use of different types of nanoparticles for nucleic acid delivery into melanoma cells and highlight the most significant outcomes.

Statins Prevent Biochemical Recurrence of Prostate Cancer After Radical Prostatectomy: A Single-center Retrospective Study with a Median Follow-up of 51.20 Months

INTRODUCTION

Prostate cancer is the most commonly diagnosed cancer in men. Radical prostatectomy is a potentially curative alternative for localized disease, although a significant percentage of these patients will suffer a biochemical recurrence with associated mortality. A wide spectrum of anticancer properties of statins has been demonstrated and the role of these drugs in prevention and treatment of other types of cancer is being increasingly studied.

OBJECTIVE

The aim of this study was to investigate whether the use of statins is associated with reduced risk of biochemical recurrence among patients submitted to radical prostatectomy.

PATIENTS AND METHODS

We retrospectively reviewed 875 patients submitted to radical prostatectomy between January 2009 and December 2018. Approximately 45.7% of the patients were on medication with statins at the time of surgery. We evaluated a possible association between statin use and biochemical recurrence and which patients would benefit the most with statin treatment.

RESULTS

Overall, statins were associated with an approximately 40% reduction in risk of biochemical recurrence at a median follow-up time of 51.2 months (HR 0.599, p<0.05). Patients with pT2c staging (HR 0.486, p=0.017) and ISUP ≥3 (HR 0.61, p=0.011) seem to have benefited more from statin use.

CONCLUSION

In this cohort, use of statins proved beneficial in reducing the risk of biochemical recurrence among patients submitted to radical prostatectomy. Prospective studies are required to confirm this result and to evaluate its safety profile in those patients.

Anti-PD-1 immunotherapy in advanced metastatic melanoma: State of the art and future challenges

Immunotherapy with immune checkpoint inhibitors, such as anti-PD-1 drugs, is an area in increasing development for its efficacy and advantages in the treatment of advanced metastatic melanoma. In fact, immunotherapy has been the target of several and recent studies in different types of cancer, namely in melanoma, a globally growing threat. Contributing to the increasing incidence of this cancer is climate change, particularly global warming of the past century, which has increased the tendency to spend more time outdoors and, consequently, exposure to sunlight and ultraviolet radiation. Among the most relevant risk factors for melanoma is the increase in ultraviolet radiation due to ozone layer depletion, one of the main factors responsible for the incidence of new cases. Anti-PD-1 agents like Nivolumab and Pembrolizumab allow a more effective treatment, enhancing the duration of the responses to therapy and prolonging the survival of the patient. However, recent studies about safety and tolerability have stated that, although these drugs present less adverse effects and toxicity, they may lead to specific autoimmune-mediated adverse events. Overall, immunotherapy with anti-PD-1 agents represents a highly promising area in the treatment of some types of cancer such as melanoma.

Evaluation of Biodistribution of Sulforaphane after Administration of Oral Broccoli Sprout Extract in Melanoma Patients with Multiple Atypical Nevi

Broccoli sprout extract containing sulforaphane (BSE-SFN) has been shown to inhibit ultraviolet radiation-induced damage and tumor progression in skin. This study evaluated the toxicity and potential effects of oral BSE-SFN at three dosages. Seventeen patients who each had at least 2 atypical nevi and a prior history of melanoma were randomly allocated to 50, 100, or 200 μmol oral BSE-SFN daily for 28 days. Atypical nevi were photographed on days 1 and 28, and plasma and nevus samples were taken on days 1, 2, and 28. Endpoints assessed were safety, plasma and skin sulforaphane levels, gross and histologic changes, IHC for phospho-STAT3(Y705), Ki-67, Bcl-2, HMOX1, and TUNEL, plasma cytokine levels, and tissue proteomics. All 17 patients completed 28 days with no dose-limiting toxicities. Plasma sulforaphane levels pooled for days 1, 2, and 28 showed median postadministration increases of 120 ng/mL for 50 μmol, 206 ng/mL for 100 μmol, and 655 ng/mL for 200 μmol. Median skin sulforaphane levels on day 28 were 0.0, 3.1, and 34.1 ng/g for 50, 100, and 200 μmol, respectively. Plasma levels of proinflammatory cytokines decreased from day 1 to 28. The tumor suppressor decorin was increased from day 1 to 28. Oral BSE-SFN is well tolerated at daily doses up to 200 μmol and achieves dose-dependent levels in plasma and skin. A larger efficacy evaluation of 200 μmol daily for longer intervals is now reasonable to better characterize clinical and biological effects of BSE-SFN as chemoprevention for melanoma. Cancer Prev Res; 11(7); 429-38. ©2018 AACR.

Chemoprevention of Melanoma: Theoretical and Practical Considerations

BACKGROUND

Chemoprevention refers to the use of agents to reverse, suppress, or prevent carcinogenic progression of cancer. The use of chemoprevention is an unexplored strategy in melanoma prevention.

METHODS

A retrospective review of the literature was undertaken regarding the important elements in evaluating chemoprevention as a strategy in melanoma.

RESULTS

Several considerations need to be addressed before a chemoprevention agent can be moved to a large randomized trial. Statins have both experimental and epidemiologic evidence to support their further development as candidate chemopreventive agents, but the evidence is insufficient to justify large-scale phase III studies. A strong scientific rationale, a systematic approach to chemoprevention agent development with rigorous chemoprevention designs, and careful selection of surrogate endpoint biomarkers are critical issues in developing a chemoprevention strategy.

CONCLUSIONS

Addressing these relevant considerations will allow for the development of chemoprevention in melanoma.

Melanoma Chemoprevention: Current Status and Future Prospects

The incidence of skin cancers, both nonmelanoma and melanoma, is increasing in the United States. The ultraviolet radiation, mainly from sun, is considered the major cause for these neoplasms. While nonmelanoma skin cancers are far more numerous, melanoma remains the most challenging. This is because melanoma can become extremely aggressive and its incidence is increasing worldwide due to lack of effective early detection, as well as disease recurrence, following both surgery and chemotherapy. Therefore, in addition to better treatment options, newer means are required to prevent melanomas from developing. Chemoprevention is a reasonable cost-effective approach to prevent carcinogenesis by inhibiting the processes of tumor initiation, promotion and progression. Melanoma is a progressive disease, which makes it very suitable for chemopreventive interventions, by targeting the processes and molecular pathways involved in the progression of melanoma. This review discusses the roles of various chemopreventive agents such as NSAIDs, statins, vitamins and dietary agents in melanoma and highlights current advancements and our perspective on future of melanoma chemoprevention. Although considerable preclinical data suggest that melanoma may be prevented or delayed by a numerous chemopreventive agents, we realize there are insufficient clinical studies evaluating their efficacy and long-term safety for human use.

Stem cell properties in cell cultures from different stage of melanoma progression

Cutaneous melanoma is an extremely heterogenous human cancer. The most aggressive melanoma may contain deregulated cells with undifferentiated/stem cell-like phenotype. A critical mechanism by which melanoma cells enhance their invasive capacity is the dissolution of the intercellular adhesion and the acquisition of mesenchymal features as a part of an epithelial-to-mesenchymal transition. The aim of this study was to clarify the role of a stem cell-like population in human melanomas by means of melanocytic cell culture analysis obtained from distinct histotypes of primary and metastatic malignant melanoma. Patients with advanced melanoma >2 cm in diameter and/or >300 mm surface were enrolled. The melanoma cells were isolated from skin biopsies of lentigo maligna melanoma, superficial spreading melanoma, nodular melanoma, and metastatic melanoma. The colony forming unit assay and alkaline phosphatase stain were evaluated. Cells were subsequently cultured and maintained in different media to evaluate their ability to differentiate into osteogenic and adipogenic lineages. Immunohistochemistry and flow cytometry analysis were performed to evaluate antigenic markers CD90, CD73, CD105, CD146, CD20, CD166, and Nestin. This study confirms that melanoma can include heterogenous cell populations with the ability both to self-renew and to a give rise to differentiated progeny. Melanoma cells displayed intratumoral heterogeneity and dynamic antigen phenotypes. Histologically, transitions from normal skin to melanoma were associated with a gradual increase in the expression of CD146, CD20, CD133, Nestin, and CD73. These molecular profiles could be further analyzed and, in the future, used for the development of novel biomolecular targeted-therapy approaches.

Potential of long-chain n-3 polyunsaturated fatty acids in melanoma prevention

The possible antineoplastic activity of dietary long-chain n-3 polyunsaturated fatty acids (LC n-3 PUFAs) has been supported by ample preclinical studies that have identified a number of molecular factors and pathways affected by these fatty acids and involved in cell growth, apoptosis, invasion, and angiogenesis. The aim of this critical review is to assess the current state of knowledge on the potential anticancer effects of LC n-3 PUFAs against malignant melanoma, one of the most common cancers among Western populations. The results of preclinical as well as human observational and interventional studies investigating the effects of LC n-3 PUFAs in melanoma were examined. Overall, the analysis of the literature reveals that, even though a large body of information is available, further effort is needed to identify the main molecular targets of LC n-3 PUFAs in melanoma. Moreover, additional well-designed human observational studies are essential to shed further light on the issue. The results of these studies could provide support and specific information for the development of clinical studies, especially those performed in combination with conventional or innovative antineoplastic therapies.

A randomized, double-blind, placebo-controlled phase II clinical trial of lovastatin for various endpoints of melanoma pathobiology

On the basis of large cardiovascular clinical trials of lipid-lowering agents that showed a considerable decrease in the incidence of primary melanomas in the active agent arm, we have carried out a randomized, double-blind clinical trial examining the impact of lovastatin on various biomarkers of melanoma pathogenesis. Subjects with at least two clinically atypical nevi were randomized to receive oral lovastatin or placebo for a 6-month period. Clinical, histopathologic, and molecular biomarkers were evaluated for change in the two groups. Eighty subjects were randomized, evaluable, and included in the analyses. Lovastatin showed no benefit in comparison with placebo in the primary endpoint of decreasing the level of histopathologic atypia, nor in any of the secondary endpoints of decreasing clinical atypia, impact on nevus number, nor in showing significant changes in any of the molecular biomarkers. There were no significant differences in adverse event profiles for lovastatin compared with placebo. The lovastatin arm did show a significant and considerable decrease in total serum cholesterol and serum low-density lipoprotein (LDL) levels compared with placebo, an expected result. This finding bolsters confidence in subject compliance. Given the results of this trial, it is concluded that if lovastatin were to lower the incidence of melanoma, it would appear not to be doing so by reversing atypia of precursor atypical nevi over the 6-month time frame studied. Further research into the pathogenesis of melanoma and in other potential chemopreventive agents is needed.

Utility of diffusion-weighted imaging in the diagnosis of inguinal lymph node metastasis with malignant melanoma

Malignant melanoma is a malignancy of pigment-producing cells (melanocytes) located predominantly in the skin. Nodal metastases are an adverse prognostic factor compromising long term patient survival. Therefore, accurate detection of regional nodal metastases is required for optimization of treatment. Computed tomography (CT) and magnetic resonance imaging (MRI) remain the primary imaging modalities for regional staging of malignant melanoma. However, both modalities rely on size-related and morphological criteria to differentiate between benign and malignant lymph nodes, decreasing the sensitivity for detection of small metastases. Surgery is the primary mode of therapy for localized cutaneous melanoma. Patients should be followed up for metastases after surgical removal. We report here a case of inguinal lymph node enlargement with a genital vesicular lesion with a history of surgery for malignant melanoma on her thigh two years ago. CT and diffusion weighted-MRI (DW-MRI) were applied for the lymph node identification. DW-MRI revealed malignant lymph nodes due to malignant melanoma metastases correlation with pathological findings.

Targeting events in melanoma carcinogenesis for the prevention of melanoma

Melanoma is one of the few tumors that have increased in incidence over the last few decades. Strategies devoted solely to protecting against ultraviolet radiation have, at best, had a modest impact on the development of melanoma. Chemoprevention is an under-explored approach that could significantly decrease the morbidity and mortality from this deadly cancer. However, the scientific and logistical challenges of performing clinical studies in chemoprevention require innovative approaches to prove the effectiveness of putative preventive agents. There are several pharmacological and nutriceutical agents that are mechanistically linked to events in melanoma carcinogenesis that are candidates for advanced human studies. We will review the data for several promising agents, including statins, curcumin, resveratrol, silymarin and green tea, and discuss some importance issues and concepts that should be considered in any melanoma chemoprevention strategy.

Dermatology of the head and neck: skin cancer and benign skin lesions

Skin lesions are extremely common, and early detection of dangerous lesions makes skin cancer one of the most highly curable malignancies. By simply becoming aware of common lesions and their phenotypic presentation, dental professionals are empowered to detect suspicious dermatologic lesions in unaware patients. This article serves as an introduction to skin cancer and benign skin lesions for dental professionals.

Non-steroidal anti-inflammatory drugs, acetaminophen, and risk of skin cancer in the Nurses' Health Study

PURPOSE

Non-steroidal anti-inflammatory drugs (NSAIDs) have been associated with lower risk of certain cancers, but data on the effect on skin cancer risk have been limited and contradictory. We prospectively examined whether use of NSAIDS or acetaminophen was associated with a lower risk of skin cancer in women.

METHODS

The 92,125 Caucasian women in the Nurses' Health Study provided information on aspirin use in 1980. Other NSAIDs and acetaminophen were added in 1990. Medication use, frequency, and quantity were reassessed on biennial questionnaires. Through 2008, we confirmed 658 melanoma cases, 1,337 squamous cell carcinoma (SCC) cases, and had 15,079 self-reports of basal cell carcinoma (BCC). We used COX proportional hazards models to compute relative risks (RR) adjusted for known skin cancer risk factors.

RESULTS

Neither aspirin nor non-aspirin NSAID use was associated with a lower risk of melanoma, SCC, or BCC, even for women with high quantity, frequency, or duration of use. Instead, we observed an increased risk of melanoma among current aspirin users (RR = 1.32, 95 % CI 1.03-1.70), though an increase of similar magnitude among past users and lack of a dose-response effect did not support a pharmacologic mechanism. We observed a mild reduction in SCC risk in current acetaminophen users (RR = 0.88, 95 % CI 0.75-1.02), with a linear decrease in risk with greater frequency of use (p = 0.04).

CONCLUSIONS

Aspirin and other NSAIDs were not associated with a lower risk of melanoma, SCC, or BCC in women. Our large, prospective study does not support a chemoprotective effect of NSAIDs against skin cancers.

Head and neck melanoma

The incidence of malignant melanoma appears to be increasing at an alarming rate throughout the world over the past 30–40 years and continues to increase in the United States, Canada, Australia, Asia, and Europe. The behavior of head and neck melanoma is aggressive, and it has an overall poorer prognosis than that of other skin sites. The authors review the published literature and text books, intending to give an overall picture of malignant melanomas of the head and neck and a special emphasis on treatment considerations with controversies in treatment including biopsy, radiation therapy, sentinel node biopsy, and nodal dissection.

Phenformin as prophylaxis and therapy in breast cancer xenografts

BACKGROUND

Observations that diabetics treated with biguanide drugs have a reduced risk of developing cancer have prompted an enthusiasm for these agents as anti-cancer therapies. We sought to determine the efficacy of the biguanide phenformin in the chemoprophylaxis and in the treatment of oestrogen receptor (ER)-positive MCF7 and receptor triple-negative MDAMB231 xenografts in immunocompromised mice. We also compared the efficacy of phenformin and metformin in the treatment of MDAMB231.

METHODS

Immunocompromised mice were divided into groups: (1) phenformin administered for 2 weeks prior to cell injection; (2) established tumours treated with phenformin; (3) established tumours treated with metformin (only for MDAMB231 tumours); (4) untreated controls. Post-treatment tumours, liver and spleen were harvested for further analysis.

RESULTS

Phenformin significantly inhibited both the development and growth of MCF7 and MDAMB231 tumours, and for MDAMB231 at greater efficacy than metformin without murine toxicity. The number of mitotic figures was significantly fewer in xenografts treated with phenformin compared with controls. Results suggested that the mechanism of action of phenformin in vivo is consistent with AMPK activation.

CONCLUSION

Phenformin has clinical potential as an antineoplastic agent and should be considered for clinical trials both in ER-positive and triple-negative breast cancer.

Chemoprevention of melanoma

Despite advances in drug discovery programs and molecular approaches for identifying drug targets, incidence and mortality rates due to melanoma continue to rise at an alarming rate. Existing preventive strategies generally involve mole screening followed by surgical removal of the benign nevi and abnormal moles. However, due to lack of effective programs for screening and disease recurrence after surgical resection, there is a need for better chemopreventive agents. Although sunscreens have been used extensively for protecting from UV-induced melanomas, results of correlative population-based studies are controversial, with certain studies suggest increased skin cancer risk in sunscreen users. Therefore, these studies require further authentication to conclusively confirm the chemoprotective efficacy of sunscreens. This chapter reviews the current understanding regarding melanoma chemoprevention and the various strategies used to accomplish this objective.

Nonsteroidal anti-inflammatory drugs and risk of melanoma

Because nonsteroidal anti-inflammatory drugs (NSAIDs) inhibit tumor growth in vitro, we investigated the association between NSAIDs and melanoma to determine if there was epidemiologic evidence of a chemopreventive effect from these medications. Three hundred twenty-seven subjects with incident melanoma and 119 melanoma-free controls completed a structured interview assessing melanoma risk factors. The unadjusted odds ratio (OR) for use of nonaspirin NSAIDs was 0.58 (95% CI 0.31–1.11), in a comparison of subjects with melanoma to controls. After adjustment for melanoma risk factors, the OR was 0.71 (95% CI 0.23–2.02). Aspirin users had an unadjusted OR of 0.85 (95% CI 0.45–1.69) and an adjusted OR of 1.45 (95% CI 0.44–4.74). In this pilot study, we found no evidence of a significant association between analgesic use and melanoma risk when potential confounders are assessed. Based on conflicting reports in the literature, meta-analysis may be appropriate.

Melanoma chemoprevention in skin reconstructs and mouse xenografts using isoselenocyanate-4

Melanoma incidence and mortality rates continue to increase despite the use of sunscreen as well as screening programs for early surgical excision of premalignant lesions. The steady increase in melanoma incidence suggests that additional preventive approaches are needed to augment these existing strategies. One unexplored area involves targeting genes whose deregulation promotes disease development to prevent melanoma. The Akt3 signaling pathway is one key signaling cascade that plays a central role by deregulating apoptosis to promote development of approximately 70% of melanomas. Isoselenocyanate-4 (ISC-4), derived from isothiocyanates by increasing the alkyl chain length and replacing sulfur with selenium, has been developed to target this important signaling pathway in melanomas; however, its chemopreventive potential is unknown. In this study, the chemopreventive efficacy of topical ISC-4 was evaluated in a laboratory-generated human skin melanoma model containing early melanocytic lesion or advanced stage melanoma cell lines and in animals containing invasive xenografted human melanoma. Repeated topical application of ISC-4 reduced tumor cell expansion in the skin model by 80% to 90% and decreased tumor development in animals by approximately 80%. Histologic examination of ISC-4-treated skin showed no obvious damage to skin cells or skin morphology, and treated animals did not exhibit markers indicative of major organ-related toxicity. Mechanistically, ISC-4 prevented melanoma by decreasing Akt3 signaling that lead to a 3-fold increase in apoptosis rates. Thus, topical ISC-4 can delay or slow down melanocytic lesion or melanoma development in preclinical models and could impact melanoma incidence rates if similar results are observed in humans.

Anti-melanoma effects of vorinostat in combination with polyphenolic antioxidant (-)-epigallocatechin-3-gallate (EGCG)

PURPOSE

Melanoma is an aggressive neoplasm with a propensity for metastases and resistance to therapy. Previously, we showed that (-)-epigallocatechin-3-gallate (EGCG), the major polyphenolic antioxidant present in green tea, resulted in a significant decrease in the viability and growth of melanoma and induction of apoptosis via modulation of the cki-cdk-cyclin network and Bcl2 family proteins. Epigenetic regulation of gene transcription by histone deacetylase (HDAC) inhibitors is gaining momentum as a novel cancer therapy. SAHA-suberoylanilidine hydroxamic acid Zolinza (vorinostat) is the first HDAC inhibitor approved by the U.S. FDA. In this study, we determined if vorinostat alone or in combination with EGCG imparts anti-proliferative effects against human melanoma cells.

METHODS

Employing human melanoma cell lines A-375, Hs-294T and G-361, we determined the effect of vorinostat and/or EGCG on 1) growth/viability and colony formation, 2) apoptosis, and 3) the critical molecules involved in cell cycle and apoptosis regulation.

RESULTS

Our data demonstrated that the anti-proliferative effects of vorinostat were greater than or similar to those of EGCG among the cell lines tested. Furthermore, relative to monotherapy, the combination treatment resulted in significantly greater inhibition of cell proliferation, increased apoptosis, activation of p21, p27 and caspases (3, 7 and 9) and Bax as well as down-regulation of cdk2, cdk4, cyclin A, NF-kappaB protein p65/RelA and Bcl2 protein and transcript.

CONCLUSIONS

Our preclinical findings suggest that combination therapy with EGCG and vorinostat may be beneficial for the management of human melanoma.

Melanoma vasculogenic mimicry is strongly related to reactive oxygen species level

The concept of 'vasculogenic mimicry' (VM) was introduced to describe the unique ability of highly invasive tumor cells to form capillary-like structures (CLS) and matrix-rich patterned network in three-dimensional culture that mimic embryonic vasculogenic network. Recently, we have shown that CLS formation requires apoptotic cell death through activation of caspase-3-dependent mechanism. In this study, to identify some molecular determinants driving aggressive melanoma cells to express a latent 'angiogenic program' that recapitulates the early events of CLS formation, we focused on the involvement of antioxidants (AOs) in the process of melanoma VM. We have studied the effects of resveratrol, (-)-epigallocathechin gallate, N-acetyl-cysteine (NAC) and Trolox on the ability of melanoma cells to form/destroy CLS. We observed that the formation of CLS was strongly related to reactive oxygen species level. In vivo animal experiments confirmed the involvement of reactive oxygen species level in melanoma VM. To understand the molecular mechanisms of this phenomenon, we specifically looked for induction of apoptosis and vascular endothelial growth factor (VEGF) release. Western blot analysis revealed that the level of VEGF, VEGF receptors (VEGF-Rs) and active caspase-3 dramatically decreased in cells treated with AOs. Here, we also report further experiments designed to determine whether the crosstalk between AOs and apoptosis exists in melanoma VM.

Methylselenol generated from selenomethionine by methioninase downregulates integrin expression and induces caspase-mediated apoptosis of B16F10 melanoma cells

Melanoma is a highly metastatic cancer resistant to current chemotherapeutic and radiotherapeutic approaches. Several studies have shown that interactions between cancer cells and the extracellular matrix (ECM) are critical for the survival and invasion of metastatic cancer cells. In this study, we examine the effects of methylselenol generated from selenomethionine (SeMet) by methioninase (METase) on cell proliferation, adhesion, and expression of integrins in murine melanoma B16F10 cells, which are metastatic in the lungs of syngeneic C57BL/6J mice. Combined treatment with SeMet-METase decreased the expression of integrins alpha(4), beta(1), alpha(nu), and beta(3), and inhibited melanoma-ECM adhesion. Caspase-mediated apoptosis was induced following loss of cell adherence. Phosphorylation of focal adhesion kinase (FAK) and Akt, related to integrin-mediated survival, were decreased upon treatment with SeMet-METase while phosphorylation of p38, PKC-delta, and IkappaBalpha increased. In the presence of specific inhibitors of p38, PKC-delta, and NF-kappaB, expression of integrins and cell adhesion to ECM were maintained and cell apoptosis was prevented in SeMet-METase-treated melanoma cells. Treatment with caspase inhibitors restored cell viability and blocked poly (ADP-ribose) polymerase (PARP) cleavage, but did not restore integrin expression and cell adhesion to ECMs reduced by SeMet-METase. Based on these results, we propose that combined treatment with SeMet-METase induces caspase-mediated apoptosis in melanoma cells by altering integrin expression and adhesion. Furthermore, activation of p38, PKC-delta, and NF-kappaB is a prerequisite for the down-regulation of integrin expression, followed by detachment-mediated apoptosis.

Crosstalk between apoptosis and antioxidants in melanoma vasculogenic mimicry

The concept of "vasculogenic mimicry" (VM) was introduced to describe the unique ability of highly aggressive tumor cells to form capillary-like structure (CLS) and matrix-rich patterned network in three-dimensional cultures that mimic embryonic vasculogenic network. Here, we provide the experimental evidence that CLS structure formation requires apoptotic cell death through activation of caspase-dependent mechanism. Our results indicate that the formation of CLS is also related to the reactive oxygen species (ROS) levels.

Peroxisome proliferator-activated receptor alpha activation decreases metastatic potential of melanoma cells in vitro via down-regulation of Akt

PURPOSE

Peroxisome proliferator-activated receptors (PPAR) regulate lipid and glucose metabolism but their anticancer properties have been recently studied as well. We previously reported the antimetastatic activity of the PPARalpha ligand, fenofibrate, against melanoma tumors in vivo. Here we investigated possible molecular mechanisms of fenofibrate anti metastatic action.

EXPERIMENTAL DESIGN

Monolayer cultures of mouse (B16F10) and human (SkMell88) melanoma cell lines, soft agar assay, and cell migration assay were used in this study. In addition, we analyzed PPARalpha expression and its transcriptional activity in response to fenotibrate by using Western blots and liciferase-based reporter system.

RESULTS

Fenofibrate inhibited migration of B16F10 and SkMel188 cells in Transwell chambers and colony formation in soft agar. These effects were reversed by PPAR inhibitor, GW9662. Western blot analysis revealed time-dependent down-regulation of Akt and extracellular signal-regulated kinase l/2 phosphorylation in fenofibrate-treated cells. A B16F10 cell line stably expressing constitutively active Akt mutant was resistant to fenofibrate. In contrast, Akt gene silencing with siRNA mimicked the fenofibrate action and reduced the migratory ability of B16F1O cells. In addition, fenofibrate strongly sensitized BI6FIO cells to the proapoptotic drug staurosporine, further supporting the possibility that fenofibrate-induced down-regulation of Akt function contributes to fenofibrate-mediated inhibition of metastatic potential in this experimental model.

CONCLUSIONS

Our results show that the PPAR-dependent antimetastatic activity of fenofibrate involves down-regulation of Akt phosphorylation and suggest that supplementation with this drug may improve the effectiveness of melanoma chemotherapy.

Epidemiology and prevention of cutaneous melanoma

Melanoma incidence has continued to increase in all white populations, and mortality from melanoma remains high in older men worldwide. In Australia, Europe, and the United States, a substantial number of thick melanomas in older men are of the nodular subtype, a subtype lacking asymmetry or color change. Educating the public and professionals about the significance of evolving pigmented lesions as emphasized in the revised ABCDE of pigmented lesions is relevant. Targeting screening efforts toward older men will be necessary to decrease worldwide melanoma mortality. Among prevention strategies, emphasizing multiple methods of sun protection in early childhood, adolescence, and adulthood is needed to decrease sunburn rates. Chemoprevention research in melanoma should become a research priority to complement ongoing prevention strategies.

What about chemoprevention for melanoma?

PURPOSE OF REVIEW

This paper aims to critically review the potential for a chemoprevention strategy in melanoma, and to discuss new data on candidate chemoprevention agents, as chemoprevention has been suggested as an unexplored approach in melanoma.

RECENT FINDINGS

A strong scientific rationale, established long-term safety of candidate agents, and a systematic step-wise approach to chemoprevention agent development are all critical for melanoma chemoprevention research. Among potential agents, the lipid-lowering drugs, the statins, satisfy these prerequisites.

SUMMARY

Chemoprevention of cutaneous melanoma can become a valid strategy complementing current prevention approaches, as long as these important prerequisites are taken into consideration.

Alterations in the expression of the apurinic/apyrimidinic endonuclease-1/redox factor-1 (APE/Ref-1) in human melanoma and identification of the therapeutic potential of resveratrol as an APE/Ref-1 inhibitor

Apurinic/apyrimidinic endonuclease-1/redox factor-1 (APE/Ref-1) is a multifunctional protein involved in DNA base excision repair and redox regulation of many transcription factors. In different melanoma cell lines, we found that both nucleus and cytoplasm exhibited higher levels of Ref-1 compared with normal melanocytes. Similar increases of Ref-1 expression, detected by immunohistofluorescence, were also evident in nevi and malignant melanoma biopsies compared with normal skin, which were predominantly localized in the nucleus. Using recombinant adenovirus Adref-1, encoding full-length Ref-1, we transiently overexpressed APE/Ref-1 in human melanocytes, which protected these cells from UVB-induced apoptosis and increased foci formation in culture. Ref-1 overexpression also protected melanoma cells from cisplatin- or H2O2-induced apoptosis, whereas increased apoptosis was observed with Ref-1 antisense construct infection. These observations suggested that intracellular Ref-1 levels played an important role in sensitization of melanoma cells to apoptosis. Electrophoretic mobility shift assay results showed that in both cultured primary and metastatic melanomas DNA-binding activities of activator protein-1 and nuclear factor-kappaB were significantly diminished or shifted when anti-APE/Ref-1 antibody was added to deplete APE/Ref-1 from the binding complexes. Induced nuclear factor-kappaB transcriptional activities were also evident after Ref-1 overexpression. Furthermore, using three-dimensional molecular structure modeling and virtual screening, we found that resveratrol, a natural compound found in fruits and vegetables, docks into a druggable pocket of Ref-1 protein. In vitro studies revealed that resveratrol inhibited, in a dose-dependent manner, Ref-1-activated activator protein-1 DNA-binding activities as well as Ref-1 endonuclease activities and rendered melanoma cells more sensitive to dacarbazine treatment.

Antiproliferative and Antiproteolytic activity of Pentoxifylline in cultures of B16F10 Melanoma cells

PURPOSE

Pentoxifylline (PTX), a methyl xanthine derivative is widely used as a haemorheological agent in the treatment of peripheral vascular disease. In the present study, we investigated the in vitro effects of PTX on B16F10 melanoma cell proliferation, adhesion and secretion of Matrix metalloproteinases.

METHODS

The toxic range of PTX was evaluated using MTT test and colony formation assay. The cell cycle study of PTX treated cells was carried out using flow cytometric analysis. Adhesion assay of pretreated melanoma cells was carried out on extracellular matrix (ECM) substrates. The relative levels and activity of matrix metalloprotienase-9 (MMP-9) and MMP-2 were determined by gelatin zymography and western blotting.

RESULTS

Pentoxifylline significantly inhibited the in vitro proliferation of B16F10 cells in a concentration dependent manner and displayed an IC(50) of 15.2 mM. Non-cytotoxic concentration of 1-3 mM of PTX for an exposure of 24 h demonstrated significant changes in cell morphology. A significant inhibition in G1-S phase transition was observed on PTX treatment. Pretreated F10 cells showed inhibition in adhesion to ECM components and markedly inhibited the secretion of MMP-9 and MMP-2 gelatinases.

CONCLUSION

The results suggest that PTX even at non-toxic pharmacological concentrations acts as an effective antiproliferative agent with significant antiproteolytic and antiadhesive effects.

Cutaneous melanoma: pathogenesis and rationale for chemoprevention

OBJECTIVE

To critically review aspects of melanoma pathogenesis that lend themselves to a chemoprevention strategy. To discuss potential candidate chemoprevention agents with an emphasis on the lipid lowering drugs, the statins, currently, the most promising agents.

DATA SOURCES

A retrospective review of the literature.

STUDY SELECTION

Studies included those relevant to melanoma pathogenesis, to the scientific rationale of chemoprevention, and pertinent epidemiologic, pre-clinical, and clinical studies. The referenced study designs and methodologies varied.

DATA EXTRACTION AND SYNTHESIS

Data were extracted by two reviewers, and the main results are presented in a quantitative descriptive manner.

CONCLUSION

Melanoma is a preventable disease by altering behavior (sun exposure) among at-risk individuals. There is also considerable evidence to suggest that melanoma development may be prevented or delayed by drugs of sufficiently low toxicity to make clinical trials of chemoprevention feasible and potentially successful. Among potential candidate agents, statins have compelling data for long-term safety and sufficient pre-clinical and clinical evidence for efficacy to justify their evaluation in well-designed trials in high-risk individuals, incorporating intermediate biologic endpoints.

Inhibition of melanoma cell proliferation by resveratrol is correlated with upregulation of quinone reductase 2 and p53

Resveratrol (trans-3,4',5-trihydroxystilbene) is a grape-derived polyphenol under intensive study for its potential in cancer prevention. In the case of cultured human melanoma cells, no one to our knowledge has investigated whether resveratrol exerts similar anti-proliferative activities in cells with different metastatic potential. Therefore, we examined the effects of this polyphenol on the growth of weakly metastatic Line IV clone 3 and on autologous, highly metastatic Line IV clone 1 cultured melanoma cells. Comparable inhibition of growth and colony formation resulted from treatment by resveratrol in both cell lines. Flow cytometric analysis revealed that resveratrol-treated clone 1 cells had a dose-dependent increase in S phase and a concomitant reduction in the G(1) phase. No detectable change in cell cycle phase distribution was found in similarly treated clone 3 cells. Western blots demonstrated a significant increase in the expression of the tumor suppressor gene p53, without a commensurate change in p21 and several other cell cycle regulatory proteins in both cell types. Chromatography of Line IV clone 3 and clone 1 cell extracts on resveratrol affinity columns revealed that the basal expression of dihydronicotinamide riboside quinone reductase 2 (NQO2) was higher in Line IV clone 1 than clone 3 cells. Levels of NQO2 but not its structural analog NQO1 were dose-dependently increased by resveratrol in both cell lines. We propose that induction of NQO2 may relate to the observed increased expression of p53 that, in turn, contributes to the observed suppression of cell growth in both melanoma cell lines.

Anti-proliferative and proapoptotic effects of (-)-epigallocatechin-3-gallate on human melanoma: possible implications for the chemoprevention of melanoma

Melanoma accounts for only about 4% of all skin cancer cases but most of skin cancer-related deaths. Standard systemic therapies such as interferon (IFN) have not been adequately effective in the management of melanoma. Therefore, novel approaches are needed for prevention and treatment of this disease. Chemoprevention by naturally occurring agents present in food and beverages has shown benefits in certain cancers including nonmelanoma skin cancers. Here, employing 2 human melanoma cell lines (A-375 amelanotic malignant melanoma and Hs-294T metastatic melanoma) and normal human epidermal melanocytes (NHEM), we studied the antiproliferative effects of epigallocatechin-3-gallate (EGCG), the major polyphenolic antioxidant present in green tea. EGCG treatment was found to result in a dose-dependent decrease in the viability and growth of both melanoma cell lines. Interestingly, at similar EGCG concentrations, the normal melanocytes were not affected. EGCG treatment of the melanoma cell lines resulted in decreased cell proliferation (as assessed by Ki-67 and PCNA protein levels) and induction of apoptosis (as assessed cleavage of PARP, TUNEL assay and JC-1 assay). EGCG also significantly inhibited the colony formation ability of the melanoma cells studied. EGCG treatment of melanoma cells resulted in a downmodulation of anti-apoptotic protein Bcl2, upregulation of proapoptotic Bax and activation of caspases -3, -7 and -9. Furthermore, our data demonstrated that EGCG treatment resulted in a significant, dose-dependent decrease in cyclin D1 and cdk2 protein levels and induction of cyclin kinase inhibitors (ckis) p16INK4a, p21WAF1/CIP1 and p27KIP1. Our data suggest that EGCG causes significant induction of cell cycle arrest and apoptosis of melanoma cells that is mediated via modulations in the cki-cyclin-cdk network and Bcl2 family proteins. Thus, EGCG, alone or in conjunction with current therapies, could be useful for the management of melanoma.

An introduction to dietary/supplemental omega-3 fatty acids for general health and prevention: Part II

The correction of a subtle nutritional deficiency that may reduce the risk of a future chronic disease is indeed a challenge. However, some specific examples in the past, such as the addition of folic acid to prevent neural tube defects and calcium and vitamin D to prevent osteoporosis, should provide some encouragement that some conditions can be prevented with the appropriate addition of a deficient compound. One of the most intriguing current and future impacts on public health may come from a higher intake of omega-3 fatty acids, such as alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). The omega-3 fatty acids continue to accumulate research that suggests that they may prevent a variety of diverse chronic diseases and potentially some acute clinical scenarios. In the first part of this article, the potential for these compounds to prevent certain cardiovascular conditions are discussed. In the second part, the potential for an impact in arthritis, numerous areas of cancer research, depression, maternal and child health, neurologic diseases, osteoporosis, and other medical disciplines are also briefly covered. The future appears bright for these agents, but specifically which conditions, who qualifies, testing, frequency, adequate sources, future trials, and numerous other questions need to be addressed and answered before the potential impact can catch up to the recent hype.

Chemoprevention of melanoma

The United States is experiencing a surge in the incidence of cutaneous malignant melanoma. Because melanoma is typically refractory to available anticancer therapy, exploration of preventive strategies has become a priority. In this review, the rationale for chemoprevention, a new and potentially powerful approach to controlling melanoma, is discussed. Chemoprevention success is based on the principles that ultraviolet-induced melanoma is a multistep process, and that molecular events and pathways associated with these steps can be targeted. Early studies using genetically engineered mice have begun to identify a number of relevant molecular pathways in melanoma. For example, Ras signaling pathways comprise all melanoma-related alterations in N-Ras, B-RAF, MAPK/ERK, and Rho proteins, and thus provide a host of potential molecular targets for melanoma chemoprevention. Among the available prospects, the statins, which inhibit Ras and Rho, have shown much promise as chemoprevention agents. However, thorough evaluation of chemoprevention candidates will require the identification of surrogate biomarkers for risk and molecular targets for intervention, as well as high-risk groups in which to focus clinical studies. We anticipate that melanoma chemoprevention research will progress in step with advances in genomics, proteomics, and preclinical mouse modeling, and ultimately provide us with powerful weapons in our struggle to control this escalating, often fatal disease.

Detection of mitochondrial DNA alterations in plasma of malignant melanoma patients

Genetic changes in mitochondrial DNA (mtDNA) have been detected in a variety of pathologic conditions including cancer. We hypothesized that malignant melanoma has genetic alterations in the displacement loop (D-loop) region and that these mtDNA alterations can be detected in blood as a circulating DNA melanoma marker. D-loop region from 20 melanoma cell lines, 12 metastatic melanoma specimens, and corresponding lymphocytes and plasma samples were sequenced using the CEQ 8000 XL Genetic Analysis System (Beckman Coulter). Nine of 20 (45%) melanoma cell lines and 5 of 12 (42%) melanoma specimens contained somatic mutations in the D-loop region of mtDNA. DNA alterations in the polycytosine tract (C-tract) of D-loop were detected in 6 of 20 (30%) cell lines and 2 of 12 (17%) specimens. Two of five paired plasma samples (40%) contained the same mutations as did melanoma specimens. In a comparison of lymphocytes and plasma of melanoma patients, 9 of 44 paired plasma samples (20%) contained at least one mutation compared to corresponding lymphocytes. Somatic mutations in the D-loop region of tumor and paired plasma did not correlate with the clinicopathological characteristics. However, circulating mtDNA alterations were more frequent in advanced disease. Studies indicate that circulating mtDNA mutations in the plasma of melanoma patients can be detected.

Inhibition of melanoma metastases by fenofibrate

The effect of fenofibrate, a ligand of peroxisome proliferator-activated receptor (PPAR) alpha, on the growth and metastatic potential of Bomirski hamster melanoma s.c. tumors, pigmented line (BHM Ma) was investigated in vivo. RT-PCR and Western-blot analyses revealed the presence of mRNA and protein of PPAR alpha in BHM Ma cells. The animals treated orally with fenofibrate developed significantly fewer metastatic foci in the lungs, as compared to the control group; however, primary tumor growth remained unaltered. This observation is interesting in respect of the potential use of fenofibrate in melanoma chemoprevention.

Primary cutaneous melanoma: surgical management and other treatment options

The incidence of primary cutaneous melanoma continues to increase and is a growing public health problem. By virtue of its metastatic potential, melanoma accounts for most of the deaths from cutaneous malignancies. Management of cutaneous melanoma has undergone a paradigm shift in recent years. Clinical studies have furthered our understanding of the biology of this disease and have changed the standards of care. Specifically, sentinel node biopsy and interferon as the first effective postsurgical therapy have had a significant impact on the treatment of patients with melanoma. Surgery remains the primary treatment modality for cutaneous melanoma. An adequate excision of the primary lesion accomplishes durable local control and is curative for patients without micrometastatic disease. Although the extent of surgical resection has decreased in recent years, the standard treatment for primary cutaneous melanoma remains wide surgical excision with histologically negative margins. The extent of excision is based on the theory that the incidence and radial extent of local recurrences can be predicted by specific primary tumor histopathologic characteristics. Tumor thickness and ulceration are the most important histologic features associated with prognosis and are the basis for the current recommendations for surgical treatment of the primary tumor. The extent of surgical therapy for primary melanoma is an area of ongoing debate. No clinical trial has shown a survival disadvantage for narrow versus wide excision regimens for melanoma of any thickness. Ongoing clinical trials will determine the relationship between the extent of surgical therapy for the primary tumor and the outcomes of recurrence and survival in patients with melanoma.