New approaches in metastatic melanoma: biological and molecular targeted therapies

Luteolin inhibits proliferation and induces apoptosis of human melanoma cells in vivo and in vitro by suppressing MMP-2 and MMP-9 through the PI3K/AKT pathway

Since the incidence rate of malignant melanoma is increasing annually, development of drugs against melanoma cell metastasis has become more urgent. Luteolin, a naturally occurring flavonoid, is abundant in our daily dietary intake and exhibits a wide spectrum of pharmacological properties. However, the potential anti-cancer role of luteolin in melanoma cells has not been fully investigated. In this study, we have explored whether luteolin inhibits the migration and invasion of A375 human melanoma cells and further elucidated the underlying anti-cancer molecular mechanism of luteolin in melanoma cells. A proliferation assay, flow cytometry and an apoptosis assay were applied to detect the effect of luteolin on the growth and apoptosis of A375 cells. Wound healing assay and transwell invasion assay were used to explore the impact of luteolin on the migration and invasion of A375 cells. Real-time quantitative PCR, western blot and immunofluorescence analysis were used to investigate the effects of luteolin on the expressions of MMP-2, MMP-9 and PI3K/AKT1 in A375 cells. A xenograft tumor animal model was used to investigate the anti-cancer effect of luteolin on the growth of the A375 cells in vivo. Our data indicated that luteolin significantly inhibited the proliferation, migration and invasion of A375 cells and induced the apoptosis of A375 cells in a concentration-dependent manner. Moreover, luteolin reduced the expressions of MMP-2 and MMP-9 and increased the expression of TIMP-1 and TIMP-2. Furthermore, luteolin significantly inhibited the tumor growth of A375 cells in a xenograft mouse model. The immunofluorescence and immunoblotting assays indicated that luteolin inhibited the phosphorylation of AKT1 and PI3K. In conclusion, both in vivo and in vitro studies showed that luteolin inhibited the proliferation and induced the apoptosis of A375 human melanoma cells by reducing the expressions of MMP-2 and MMP-9 through the PI3K/AKT pathway. Overall, luteolin can be considered as a promising anti-cancer agent for the treatment of human melanoma.

Gambogenic acid induces cell growth inhibition, cell cycle arrest and metastasis inhibition in choroidal melanoma in a dose-dependent manner

The aim of the present study was to explore the effects of gambogenic acid (GNA) on the malignant behaviors of choroidal melanoma cells, including cell viability, cell cycle, migration and invasion, and to elucidate the underlying regulatory mechanism. The human choroidal melanoma cell line OCM-1 was treated with different concentrations of GNA and cell viability, colony formation ability, cell cycle, migration and invasion were analyzed. Additionally, cells were incubated with or without LY294002, a specific inhibitor of the phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) signaling pathway, for 24 h. Levels of cell cycle-associated proteins (cyclin D1, cyclin E, cyclin-dependent kinase 2 and P21), epithelial-mesenchymal transition (EMT)-associated molecules (epithelial-cadherin, α-smooth muscle actin and vimentin) and phosphorylated (p)-AKT/AKT were determined using reverse transcription-quantitative polymerase chain reaction and western blot analysis. The results demonstrated that GNA significantly inhibited cell viability and induced cell cycle arrest at the G0/G1 phase in a dose-dependent manner (P<0.01). Furthermore, GNA administration significantly suppressed cell migration and invasion in a dose-dependent manner (P<0.01). Treatment with GNA or LY294002 induced a marked decrease in the expression of p-AKT/AKT, a significant downregulation in cell cycle-associated molecules (P<0.01), and a significant decrease in cell viability (P<0.01). Co-treatment with LY294002 and GNA had an additive effect on the growth of OCM-1 cells. In conclusion, the results of the present study suggest that treatment with GNA may inhibit cell viability and induce G0/G1 arrest. Furthermore, GNA may also inhibit cell metastasis via regulating EMT-associated molecules. The PI3K/Akt signaling pathway may be a key mechanism involved in the progression of choroidal melanoma, and GNA may serve as a potential therapeutic reagent for the treatment of this disease.

A combination of high dose rate (10X FFF/2400 MU/min/10 MV X-rays) and total low dose (0.5 Gy) induces a higher rate of apoptosis in melanoma cells in vitro and superior preservation of normal melanocytes

The aim of this study was to determine the apoptotic effects, toxicity, and radiosensitization of total low dose irradiation delivered at a high dose rate in vitro to melanoma cells, normal human epidermal melanocytes (HEM), or normal human dermal fibroblasts (HDF) and to study the effect of mitochondrial inhibition in combination with radiation to enhance apoptosis in melanoma cells. Cells irradiated using 10X flattening filter-free (FFF) 10 MV X-rays at a dose rate of 400 or 2400 MU/min and a total dose of 0.25–8 Gy were analyzed by cell/colony counting, MitoTracker, MTT, and DNA-damage assays, as well as by quantitative real-time reverse transcriptase PCR in the presence or absence of mitochondrial respiration inhibitors. A dose rate of 2400 MU/min killed on average five-fold more melanoma cells than a dose rate 400 MU/min at a total dose of 0.5 Gy and preserved 80% survival of HEM and 90% survival of HDF. Increased apoptosis at the 2400 MU/min dose rate is mediated by greater DNA damage, reduced cell proliferation, upregulation of apoptotic genes, and downregulation of cell cycle genes. HEM and HDF were relatively unharmed at 2400 MU/min. Radiation induced upregulation of mitochondrial respiration in both normal and cancer cells, and blocking the respiration with inhibitors enhanced apoptosis only in melanoma cells. A high dose rate with a low total dose (2400 MU/min, 0.5 Gy/10X FFF 10 MV X-rays) enhances radiosensitivity of melanoma cells while reducing radiotoxicity toward HEM and HDF. Selective cytotoxicity of melanoma cells is increased by blocking mitochondrial respiration.

Multivalent presentation of a hydrolytically stable GM(3) lactone mimetic as modulator of melanoma cells motility and adhesion

A hydrolytically stable mimetic of the tumour antigen GM(3) lactone is used to decorate multivalent scaffolds. Two of them positively interfere on melanoma cell adhesion, migration and resistance to apoptosis (anoikis). Notably, their ability to hamper melanoma-cells adhesion and reduce the metastatic potential is enhanced when the two scaffolds, presenting a different shape, are used in combination.

Specifically targeting ERK1 or ERK2 kills melanoma cells

Background

Overcoming the notorious apoptotic resistance of melanoma cells remains a therapeutic challenge given dismal survival of patients with metastatic melanoma. However, recent clinical trials using a BRAF inhibitor revealed encouraging results for patients with advanced BRAF mutant bearing melanoma, but drug resistance accompanied by recovery of phospho-ERK (pERK) activity present challenges for this approach. While ERK1 and ERK2 are similar in amino acid composition and are frequently not distinguished in clinical reports, the possibility they regulate distinct biological functions in melanoma is largely unexplored.

Methods

Rather than indirectly inhibiting pERK by targeting upstream kinases such as BRAF or MEK, we directly (and near completely) reduced ERK1 and ERK2 using short hairpin RNAs (shRNAs) to achieve sustained inhibition of pERK1 and/or pERK2.

Results and discussion

Using A375 melanoma cells containing activating BRAF^V600E mutation, silencing ERK1 or ERK2 revealed some differences in their biological roles, but also shared roles by reduced cell proliferation, colony formation in soft agar and induced apoptosis. By contrast, chemical mediated inhibition of mutant BRAF (PLX4032) or MEK (PD0325901) triggered less killing of melanoma cells, although they did inhibit proliferation. Death of melanoma cells by silencing ERK1 and/or ERK2 was caspase dependent and accompanied by increased levels of Bak, Bad and Bim, with reduction in p-Bad and detection of activated Bax levels and loss of mitochondrial membrane permeability. Rare treatment resistant clones accompanied silencing of either ERK1 and/or ERK2. Unexpectedly, directly targeting ERK levels also led to reduction in upstream levels of BRAF, CRAF and pMEK, thereby reinforcing the importance of silencing ERK as regards killing and bypassing drug resistance.

Conclusions

Selectively knocking down ERK1 and/or ERK2 killed A375 melanoma cells and also increased the ability of PLX4032 to kill A375 cells. Thus, a new therapeutic window is open for future clinical trials in which agents targeting ERK1 and ERK2 should be considered in patients with melanoma.

Melanoma update: diagnostic and prognostic factors that can effectively shape and personalize management

Routine light microscopy remains a powerful tool to diagnose, stage and prognose melanoma. Although it is very economical and efficient, it requires a significant level of expertise and, in difficult cases the final diagnosis is affected by subjective interpretation. Fortunately, new insights into the genomic aberrations characteristic of melanoma, coupled with ancillary studies, are further refining evaluation and management allowing for more confident diagnosis, more accurate staging and the selection of targeted therapy. In this article, we review the standard of care and new updates including four probe FISH, the 2009 American Joint Commission on Cancer staging of melanoma and mutant testing of melanoma, which will be crucial for targeted therapy of metastatic melanoma.

BRAFV600E mutation in papillary thyroid carcinoma: a potential target for therapy?

This article reviews the therapeutic significance of the close genotype-phenotype association in papillary thyroid carcinoma, namely regarding the association between genetic alterations in RET, BRAF or RAS genes and the histopathological variants of papillary thyroid carcinoma. Based upon the aforementioned review on morphology and molecular pathology, the most recent prognostic and therapeutic data are reviewed and the role of targeted therapies, namely those interfering with BRAF-activated pathways are discussed, which may play a role in the treatment of patients with papillary thyroid carcinoma unresponsive to radioactive iodine.

Genetically engineered Newcastle disease virus for malignant melanoma therapy

Despite the advances in cancer therapies in the past century, malignant melanoma continues to present a significant clinical challenge due to lack of chemotherapeutic response. Systemic therapy with immunostimulatory agents such as interferon and interleukin-2 (IL-2) has shown some promise, though each is associated with significant side effects. Over the past 50 years, oncolytic Newcastle disease virus (NDV) has emerged as an alternative candidate for cancer therapy. The establishment of reverse-genetics systems for the virus has allowed us to further manipulate the virus to enhance its oncolytic activity. Introduction of immunomodulatory molecules, especially IL-2, into the NDV genome was shown to enhance the oncolytic potential of the virus in a murine syngeneic colon carcinoma model. We hypothesize that a recombinant NDV expressing IL-2 would be an effective agent for therapy of malignant melanoma. We show that recombinant NDV possesses a strong cytolytic activity against multiple melanoma cell lines, and is effective in clearing established syngeneic melanoma tumors in mice. Moreover, introduction of murine IL-2 into NDV significantly enhanced its activity against syngeneic melanomas, resulting in increased overall animal survival and generation of antitumor immunity. These findings warrant further investigations of IL-2-expressing NDV as an antimelanoma agent in humans.

The sodium pump alpha1 sub-unit: a disease progression-related target for metastatic melanoma treatment

Melanomas remain associated with dismal prognosis because they are naturally resistant to apoptosis and they markedly metastasize. Up-regulated expression of sodium pump α sub-units has previously been demonstrated when comparing metastatic to non-metastatic melanomas. Our previous data revealed that impairing sodium pump α1 activity by means of selective ligands, that are cardiotonic steroids, markedly impairs cell migration and kills apoptosis-resistant cancer cells. The objective of this study was to determine the expression levels of sodium pump α sub-units in melanoma clinical samples and cell lines and also to characterize the role of α1 sub-units in melanoma cell biology. Quantitative RT-PCR, Western blotting and immunohistochemistry were used to determine the expression levels of sodium pump α sub-units. In vitro cytotoxicity of various cardenolides and of an anti-α1 siRNA was evaluated by means of MTT assay, quantitative videomicroscopy and through apoptosis assays. The in vivo activity of a novel cardenolide UNBS1450 was evaluated in a melanoma brain metastasis model. Our data show that all investigated human melanoma cell lines expressed high levels of the α1 sub-unit, and 33% of human melanomas displayed significant α1 sub-unit expression in correlation with the Breslow index. Furthermore, cardenolides (notably UNBS1450; currently in Phase I clinical trials) displayed marked anti-tumour effects against melanomas in vitro. This activity was closely paralleled by decreases in cMyc expression and by increases in apoptotic features. UNBS1450 also displayed marked anti-tumour activity in the aggressive human metastatic brain melanoma model in vivo. The α1 sodium pump sub-unit could represent a potential novel target for combating melanoma.

How molecular pathology is changing and will change the therapeutics of patients with follicular cell-derived thyroid cancer: Table 1

Well-differentiated thyroid carcinomas comprise two well-defined histological types: papillary and follicular (PTCs and FTCs, respectively). Despite being derived from the same cell (thyroid follicular cell), these two types of tumour accumulate distinct genetic abnormalities during progression. The molecular pathology of thyroid cancer is now better understood because of our ability to identify RET/PTC rearrangements and BRAF mutations in the aetiopathogenesis of the large majority of PTCs and the high prevalence of RAS mutations and PAX8/PPARγ rearrangements in follicular patterned carcinomas (FTCs and follicular variant of PTCs). This review summarises most of the molecular alterations currently used as targets for new biological treatments and looks at some of the changes that are already occurring or may occur in the treatment of patients with thyroid cancer. For simplicity, the review is divided up according to the major genetic alterations identified in well-differentiated thyroid carcinomas (RET/PTC rearrangements, BRAF mutations, RAS mutations and mitochondrial DNA deletions and mutations) and their respective treatments.

Extensive necrosis of visceral melanoma metastases after immunotherapy

BACKGROUND

The prognosis for metastatic melanoma remains poor even with traditional decarbazine or interferon therapy. 5-year survival is markedly higher amongst patients undergoing metastatectomy. Unfortunately not all are suitable for metastatectomy. Alternative agents for systemic therapy have, to date, offered no greater rates of survival beyond traditional therapy. A toll-like receptor 9 agonist, PF-3512676 (formerly known as CPG 7909) is currently being evaluated for its potential.

CASE PRESENTATION

We present the case of a 54-year-old Caucasian male with completely resected metastatic cutaneous melanoma after immunotherapy. The patient initially progressed during adjuvant high-dose interferon, with metastases to the liver, spleen, and pelvic lymph nodes. During an 18-month treatment period with PF-3512676 (formerly known as CPG 7909), a synthetic cytosine-phosphorothioate-guanine rich oligodeoxynucleotide, slow radiologic disease progression was demonstrated at the original disease sites. Subsequent excision of splenic and pelvic nodal metastases was performed, followed by resection of the liver metastases. Histologic examination of both hepatic and splenic melanoma metastases showed extensive necrosis. Subsequent disease-free status was demonstrated by serial positron emission tomography (PET).

CONCLUSION

Existing evidence from phase I/II trials suggests systemic treatment with PF-3512676 is capable of provoking a strong tumor-specific immune response and may account for the prolonged tumor control in this instance.

Is B-Raf a good therapeutic target for melanoma and other malignancies?

The RAF family members, A-Raf, B-Raf, and C-Raf (or Raf-1), are intermediate molecules in the mitogen-activated protein (MAP) kinase [Ras/Raf/MAP kinase/extracellular signal-regulated kinase (Erk) kinase (MEK)/Erk] pathway, which relays extracellular signals from the cell membrane to the nucleus via a cascade of phosphorylation events ultimately promoting cancer development. This pathway is activated by mutation in approximately 7% of all human cancers. B-Raf is one of the proteins frequently mutated to an active form during tumor development. Therefore, B-Raf is an attractive cancer target but lack of clinical efficacy using agents targeting this protein has raised serious doubts about its therapeutic utility. Design of more effective B-Raf inhibitory agents, targeting other members of the signaling cascade for greater clinical efficacy or inhibiting B-Raf in combination with other targets, is being evaluated to resolve these perplexing issues. Here, we discuss recent progress, using preclinical models and clinical studies, to resolve the controversy of whether B-Raf would be a good therapeutic target for melanoma and other malignancies.

Apoptosis pathways and oncolytic adenoviral vectors: promising targets and tools to overcome therapy resistance of malignant melanoma

In the last decades melanoma incidence has been increasing worldwide, while mortality remained on a high level. Until now, there is no suitable therapy for metastasized melanoma, which could lead to a significant increase in overall survival. Apoptosis deficiency is supposed to be a critical factor for therapy resistance, and previous work has characterized the basic mechanisms of apoptosis regulation in melanoma. Genes and strategies suitable for efficient induction of apoptosis in melanoma cells were identified, which are based on proapoptotic Bcl-2 proteins (Bcl-x(S), Bcl-x(AK), Bik/Nbk and Bax) as well as on tumor necrosis factor (TNF)-related death ligands (CD95L/Fas ligand and TNF-related apoptosis-inducing ligand, TRAIL). Proapoptotic genes may be employed in improved gene therapeutic strategies, based on conditional oncolytic adenoviral vectors.

Adjuvant therapy of malignant melanoma

High risk surgically resected melanoma is associated with a less than 50% 5-year survival. Adjuvant therapy is an appropriate treatment modality in this setting, and is more likely to be effective as the tumour burden here is small. Clinical observations of spontaneous tumour regressions and a highly variable rate of disease progression suggest a role of the immune system in the natural history of melanoma. Biological agents have therefore been the subjects of numerous adjuvant studies. Early, randomised controlled trials (RCTs) of Bacillus Calmette-Guerin (BCG), levamisole, Corynebacterium parvum, chemotherapy, isolated limb perfusion (ILP), radiotherapy, transfer factor (TF), megestrol acetate and vitamin A yielded largely negative results. Current trials focus on vaccines and the interferons. To date the latter is the only therapy to have shown a significant benefit in the prospective randomised controlled phase III setting. This report represents a systematic review of studies in adjuvant therapy in melanoma. Data from ongoing studies is awaited before a role for adjuvant agents in high risk melanoma is confirmed.

Adjuvant therapy for cutaneous malignant melanoma

We discuss the current status of adjuvant therapy for melanoma by first reviewing the rationale and goals of adjuvant therapy and then analyzing the results of published randomized trials. We pay particular attention to adjuvant interferon trials that raise many challenging issues in the management of patients with melanoma at high risk of recurrence. Past adjuvant trials have used immunotherapeutic approaches, chemotherapy, radiation therapy, as well as hormonal and retinoid therapy. We also summarize ongoing adjuvant trials.

The role of adjuvant therapy in melanoma management

Adequate wide excision of a primary cutaneous melanoma is associated with a 10-year cure rate of 85% when the tumor's depth is less than 1.5 mm (American Joint Committee on Cancer [AJCC] Stage I). However, 50% of patients with deep (> 4 mm) primary melanomas, 60-85% of those with regional lymph node metastases (AJCC Stage III), and 95% of those with metastases to distant sites (AJCC Stage IV) will experience recurrence, which is associated with a dismal prognosis. Adjuvant therapy of melanoma assumes that treatment will be more effective when the tumor burden is small. In the 1970s and 1980s, randomized trials tested the efficacy of chemotherapy, nonspecific immunotherapy, levamisole, and regional perfusion therapy in patients with AJCC Stage II and III melanoma. Dacarbazine (DTIC) alone or in combination with other chemotherapeutic drugs or with nonspecific immunotherapy did not significantly improve disease free or overall survival. Of the four levamisole trials, only the study conducted by the National Cancer Institute of Canada revealed a reduction in recurrence and mortality; however, this reduction was not significant by multivariate analysis. The value of regional perfusion therapy following resection of high risk extremity melanomas is currently being determined by multiinstitutional studies conducted by the World Health Organization and the North American Perfusion Group. Multi-institutional trials also are examining the adjuvant role of interferon-alpha in patients with deep (> 3 mm) primary melanomas or positive regional lymph nodes; results should reveal its optimum dose and duration of treatment (3 x 10(6) U for > or = 2 years versus 10 x 10(6) U/m2 for 1 year, subcutaneously 3 times a week) and its impact on survival. A randomized trial of interferon-gamma undertaken by the Southwest Oncology Group was discontinued after interim analysis indicated an adverse effect. Phase II trials indicate that active specific immunotherapy can alter the natural course of AJCC Stage III and IV melanoma following surgical resection of nodal or distant metastases. Upcoming results of Phase III trials will establish the role of active specific immunotherapy for adjuvant treatment of patients with resected AJCC Stage III and IV melanoma.

Long term response to chemotherapy in patients with visceral metastatic melanoma

PATIENTS AND METHODS

Eight patients who remain in long term remission 4 to 15 years after chemotherapy for visceral metastatic melanoma are described. These patients were observed among some 1100 patients with visceral melanoma seen at the Sydney Melanoma Unit between 1977 and 1989. Only about one-third of such patients received chemotherapy, almost always with single agent dacarbazine or a nitrosourea.

RESULTS

The apparently cured patients did not differ from the overall group of patients with visceral metastases in baseline characteristics, but 6 of the 8 had nodular lung metastases.

CONCLUSIONS

While the mechanism remains uncertain, one possibility could be that chemotherapeutic agents cause mutations which allow expression of antigenicity in tumour cells. In any case, the fact of occasional exceptionally good responses, perhaps amounting to cure, constitutes an argument for a trial of chemotherapy in patients with visceral metastatic melanoma.

Systemic chemotherapy for malignant melanoma

Malignant melanoma is notoriously resistant to chemotherapy. Standard single agents include dacarbazine and the nitrosoureas, but most series treating patients with metastatic melanoma report response rates of about 20%. Occasional patients, however, achieve long term remission, amounting to cure, after such treatment. Adjuvant studies have failed to define any systemic therapy of value after surgery for primary or regional lymph node disease. Combinations of drugs have not been shown to be superior to single agents. Cisplatin and fotemustine are among the newer agents with activity. Isolated limb perfusion with melphalan and systemic therapy with high dose alkylating agents and marrow transplantation suggest that the resistance to conventional concentrations of alkylating agents is not absolute. One strategy to improve the efficacy of alkylating agents may therefore be the modulation of cellular glutathione or glutathione-S-transferase. Biological response modifiers remain of interest, though many of the protocols with the best response rates are impractical for routine use. Many patients with asymptomatic metastatic melanoma should be observed without treatment. Outside clinical trials, it is reasonable to use single agent dacarbazine or lomustine if chemotherapy is required.

Intraarterial infusion chemotherapy in regionally advanced malignant melanoma

The therapeutic effectiveness of intraarterial cisplatin (CDDP) and dacarbazine (DTIC) infusion was examined in 30 evaluable patients with regionally advanced melanoma that was refractory to standard treatments. Objective responses were achieved in 11 patients (37%), including three complete (10%) and eight partial (27%) tumor regressions. Successful debulking surgery was performed in seven of the eleven patients with response. Six remained free of regional disease after a median time of 25 months, and four are also free of distant metastases at 24+, 25+, 41+, and 54+ months. Nineteen of thirty patients with no significant tumor response underwent alternative treatments. Debulking surgery was performed in nine, but with little palliative gain, since seven relapsed at a median time of 5 months. Our results suggest that a combined therapeutic approach--preoperative chemotherapy followed by surgery in responding tumors--represents an effective treatment for patients with regionally advanced melanoma.