BRAF Signaling and Targeted Therapies in Melanoma

Dissecting the multifaceted roles of autophagy in cancer initiation, growth, and metastasis: from molecular mechanisms to therapeutic applications

Autophagy is a cytoplasmic defense mechanism that cells use to break and reprocess their intracellular components. This utilization of autophagy is regarded as a savior in nutrient-deficient and other stressful conditions. Hence, autophagy keeps contact with and responds to miscellaneous cellular tensions and diverse pathways of signal transductions, such as growth signaling and cellular death. Importantly, autophagy is regarded as an effective tumor suppressor because regular autophagic breakdown is essential for cellular maintenance and minimizing cellular damage. However, paradoxically, autophagy has also been observed to promote the events of malignancies. This review discussed the dual role of autophagy in cancer, emphasizing its influence on tumor survival and progression. Possessing such a dual contribution to the malignant establishment, the prevention of autophagy can potentially advocate for the advancement of malignant transformation. In contrast, for the context of the instituted tumor, the agents of preventing autophagy potently inhibit the advancement of the tumor. Key regulators, including calpain 1, mTORC1, and AMPK, modulate autophagy in response to nutritional conditions and stress. Oncogenic mutations like RAS and B-RAF underscore autophagy's pivotal role in cancer development. The review also delves into autophagy's context-dependent roles in tumorigenesis, metastasis, and the tumor microenvironment (TME). It also discusses the therapeutic effectiveness of autophagy for several cancers. The recent implication of autophagy in the control of both innate and antibody-mediated immune systems made it a center of attention to evaluating its role concerning tumor antigens and treatments of cancer.

Immunotherapy in the Management of Sinonasal Mucosal Melanoma: A Systematic Review

OBJECTIVE

The aim of this work is to comprehensively review and synthesize the literature related to sinonasal mucosal melanoma (SNMM) treatment with immunotherapy, including potentially targetable genetic mutations, survival outcomes, and adverse events.

DATA SOURCES

Embase, Cochrane, Scopus, and Web of Science.

REVIEW METHODS

The study protocol was designed according to Preferred Reporting Items for Systematic Reviews and Meta-analysis statement. Databases were searched from inception through May 23, 2023.

RESULTS

A total of 42 studies met inclusion criteria. Twenty-four of the included studies reported genetic mutations for a combined 787 patients with SNMM. 8.1% (95% confidence interval, CI: 7.6-8.6), 18.9% (95% CI: 18.1-19.8), and 8.5% (95% CI: 8.1-9.0) of reported patients were positive for BRAF, NRAS, and KIT mutations, respectively. The presence of brisk tumor-infiltrating lymphocytes was associated with improved recurrence-free survival and overall survival (OS). Six studies reported a combined 5-year OS after adjuvant immunotherapy treatment of 42.6% (95% CI: 39.4-45.8). Thirteen studies encompassing 117 patients reported adjuvant or salvage immune checkpoint inhibitor (ICI) immunotherapy response rates: 40.2% (95% CI: 36.8-43.6) had a positive response (tumor volume reduction or resolution). Eleven studies reported direct comparisons between SNMM patients treated with or without immunotherapy; the majority (7/11) reported survival benefit for their entire cohort or select subgroups of SNMM patients. With the transition to modern ICIs, there is a stronger trend toward survival improvement with adjuvant ICI. Tumors with Ki67 <40% may respond better to ICI's.

CONCLUSION

ICI therapy can be an effective in select SNMM patients, especially those with advanced/metastatic disease.

Correlation Analyses between Histological Staging and Molecular Alterations in Tumor-Derived and Cell-Free DNA of Early-Stage Primary Cutaneous Melanoma

Here, we investigate the correlation and statistical analyses between histological staging and molecular alterations in tumor-derived (tdDNA) and cell-free DNA (cfDNA) obtained from early-stage primary cutaneous melanoma (PCM) patients using digital PCR (dPCR) for the detection of the BRAF p.V600E somatic pathogenic variant. In the prospective study, a total of 68 plasma and paired tdDNA samples, and in the retrospective cohort, a total of 100 tdDNA samples were analyzed using dPCR and reverse hybridization StripAssay. The Breslow depth (BD) and Clark level were applied to categorize the study population. Our results demonstrate that dPCR is a highly sensitive and specific method for the detection of BRAF p.V600E somatic variants in cfDNA samples from PCM patients. A strong correlation was detected between BD and cfDNA concentration in all mutant and negative cases, between the tdDNA concentration and the tumor-derived variant allele frequency (VAF) of BRAF p.V600E, between the tdVAF and the cfVAF in all cases, and between the cfDNA and cfVAF in mutant cases. The tdVAF and cfVAF of BRAF p.V600E and cfDNA concentration were the highest in Clark's V category. The cfDNA concentration was statistically significantly higher in Clark's III, IV, and V groups compared to cases with a better prognosis. It can also be explained by the fact that cases with a more advanced stage classification release more cfDNA into the peripheral circulation.

Alpha-melanocyte stimulating hormone (α-MSH): biology, clinical relevance and implication in melanoma

Alpha-melanocyte stimulating hormone (α-MSH) and its receptor, melanocortin 1 receptor (MC1R), have been proposed as potential target for anti-cancer strategies in melanoma research, due to their tissue specific expression and involvement in melanocyte homeostasis. However, their role in prevention and treatment of melanoma is still debated and controversial. Although a large body of evidence supports α-MSH in preventing melanoma development, some preclinical findings suggest that the α-MSH downstream signalling may promote immune escape and cancer resistance to therapy. Additionally, in metastatic melanoma both MC1R and α-MSH have been reported to be overexpressed at levels much higher than normal cells. Furthermore, targeted therapy (e.g. BRAF inhibition in BRAFV600E mutant tumours) has been shown to enhance this phenomenon. Collectively, these data suggest that targeting MC1R could serve as an approach in the treatment of metastatic melanoma. In this review, we explore the molecular biology of α-MSH with particular emphasis into its tumor-related properties, whilst elaborating the experimental evidence currently available regarding the interplay between α-MSH/MC1R axis, melanoma and antitumor strategies.

Challenges and Opportunities in the Crusade of BRAF Inhibitors: From 2002 to 2022

Serine/threonine-protein kinase B-Raf (BRAF; RAF = rapidly accelerated fibrosarcoma) plays an important role in the mitogen-activated protein kinase (MAPK) signaling cascade. Somatic mutations in the BRAF gene were first discovered in 2002 by Davies et al., which was a major breakthrough in cancer research. Subsequently, three different classes of BRAF mutants have been discovered. This class includes class I monomeric mutants (BRAFV600), class II BRAF homodimer mutants (non-V600), and class III BRAF heterodimers (non-V600). Cancers caused by these include melanoma, thyroid cancer, ovarian cancer, colorectal cancer, nonsmall cell lung cancer, and others. In this study, we have highlighted the major binding pockets in BRAF protein, their active and inactive conformations with inhibitors, and BRAF dimerization and its importance in paradoxical activation and BRAF mutation. We have discussed the first-, second-, and third-generation drugs approved by the Food and Drug Administration and drugs under clinical trials with all four different binding approaches with DFG-IN/OUT and αC-IN/OUT for BRAF protein. We have investigated particular aspects and difficulties with all three generations of inhibitors. Finally, this study has also covered recent developments in synthetic BRAF inhibitors (from their discovery in 2002 to 2022), their unique properties, and importance in inhibiting BRAF mutants.

Dabrafenib-Trametinib and Radiotherapy for Oligoprogressive BRAF Mutant Advanced Melanoma

The clinical management of metastatic melanoma has been changed by BRAF (BRAFi) and MEK inhibitors (MEKi), which represent a standard treatment for BRAF-mutant melanoma. In oligoprogressive melanoma patients with BRAF mutations, target therapy can be combined with loco-regional radiotherapy (RT). However, the association of BRAF/MEK inhibitors and RT needs to be carefully monitored for potential increased toxicity. Despite the availability of some reports regarding the tolerability of RT + target therapy, data on simultaneous RT and BRAFi/MEKi are limited and mostly focused on the BRAFi vemurafenib. Here, we report a series of metastatic melanoma patients who received fractioned RT regimens for oligoprogressive disease in combination with the BRAFi dabrafenib and the MEKi trametinib, which have continued beyond progression. None of the cases developed relevant adverse events while receiving RT or interrupted dabrafenib and trametinib administration. These cases suggest that a long period of dabrafenib/trametinib interruption during radiotherapy for oligoprogressive disease can be avoided. Prospective trials are warranted to assess the efficacy and safety of the contemporary administration of BRAF/MEK inhibitors and radiotherapy for oligoprogressive disease.

EIF3B stabilizes PTGS2 expression by counteracting MDM2-mediated ubiquitination to promote the development and progression of malignant melanoma

Malignant melanoma (MM) is a neoplasm that develops from human melanocytes. It was reported that eukaryotic translation initiation factor 3 subunit B (EIF3B) is associated with multiple types of cancers, but its role in MM has not been reported. In the present study, we found that EIF3B was abundantly expressed in MM and was strongly related to lymphatic metastasis and pathological stage of MM patients. In addition, EIF3B depletion could block the progression of MM in vitro and in vivo. In contrast, EIF3B overexpression increased cell proliferation and migration in melanoma cells. More importantly, we identified that EIF3B's driver role in MM was mediated by PTGS2. In detail, we found that EIF3B stabilized PTGS2 expression by inhibiting PTGS2 ubiquitination, which is mediated by the E3 ligase MDM2. Moreover, like EIF3B, silencing PTGS2 could suppress MM development, and more interestingly, it could reverse the situation caused by overexpression of EIF3B in vitro and in vivo. Furthermore, the proliferation and migration inhibited by silencing of EIF3B were also partially recovered by overexpression of PTGS2. Overall, our findings revealed the potential of EIF3B as a therapeutic target for MM. Identification of EIF3B's function in MM may pave the way for future development of more specific and more effective targeted therapy strategies against MM.

Gaussian field-based 3D-QSAR and molecular simulation studies to design potent pyrimidine-sulfonamide hybrids as selective BRAFV600E inhibitors

The "RAS-RAF-MEK-ERK" pathway is an important signaling pathway in melanoma. BRAF^V600E (70-90%) is the most common mutation in this pathway. BRAF inhibitors have four types of conformers: type I (αC-IN/DFG-IN), type II (αC-IN/DFG-OUT), type I_1/2 (αC-OUT/DFG-IN), and type I/II (αC-OUT/DFG-OUT). First- and second-generation BRAF inhibitors show resistance to BRAF^V600E and are ineffective against malignancies induced by dimer BRAF mutants causing 'paradoxical' activation. In the present study, we performed molecular modeling of pyrimidine-sulfonamide hybrids inhibitors using 3D-QSAR, molecular docking, and molecular dynamics simulations. Previous reports reveal the importance of pyrimidine and sulfonamide moieties in the development of BRAF^V600E inhibitors. Analysis of 3D-QSAR models provided novel pyrimidine sulfonamide hybrid BRAF^V600E inhibitors. The designed compounds share similarities with several structural moieties present in first- and second-generation BRAF inhibitors. A total library of 88 designed compounds was generated and molecular docking studies were performed with them. Four molecules (T109, T183, T160, and T126) were identified as hits and selected for detailed studies. Molecular dynamics simulations were performed at 900 ns and binding was calculated. Based on molecular docking and simulation studies, it was found that the designed compounds have better interactions with the core active site [the nucleotide (ADP or ATP) binding site, DFG motif, and the phospho-acceptor site (activation segment) of BRAF^V600E protein than previous inhibitors. Similar to the FDA-approved BRAF^V600E inhibitors the developed compounds have [αC-OUT/DFG-IN] conformation. Compounds T126, T160 and T183 interacted with DIF (Leu505), making them potentially useful against BRAF^V600E resistance and malignancies induced by dimer BRAF mutants. The synthesis and biological evaluation of the designed molecules is in progress, which may lead to some potent BRAF^V600E selective inhibitors.

Synthesis, Anticancer Activities and Molecular Docking Studies of a Novel Class of 2-Phenyl-5,6,7,8-tetrahydroimidazo [1,2-b]pyridazine Derivatives Bearing Sulfonamides

In the present study, new 2-phenyl-5,6,7,8-tetrahydroimidazo [1,2-b]pyridazines bearing sulfonamides were synthesized, characterized and evaluated for their anticancer activities. The structures of these derivatives were elucidated by 1H NMR, 13C NMR, infrared and high-resolution mass spectrometry for further validation of the target compound structures. The anticancer activities of the new molecules were evaluated against five human cancer cell lines, including A-549, Hs-683, MCF-7, SK-MEL-28 and B16-F10 cell lines using 5-fluorouracil and etoposide as the reference drugs. Among the tested compounds, 4e and 4f exhibited excellent activities in the same range of the positive controls, 5-fluorouracil and etoposide, against MCF-7 and SK-MEL-28 cancer cell lines, with IC50 values ranging from 1 to 10 μM. The molecular docking studies of 4e and 4f showed a strong binding with some kinases, which are linked to MCF-7 and SK-MEL-28 cancer cell lines.

Combination targeted and immune therapy in the treatment of advanced melanoma: a valid treatment option for patients?

Melanomas harboring an activating BRAFV600 mutation account for 50% of all advanced melanomas. The approval of BRAF-targeted therapy revolutionized treatment of these patients with achievement of impressive responses. However, development of resistance to these drugs is a significant problem, and as such, duration of response remains low, with median progression free survival of around 11–15 months. Immune checkpoint blockers exploit the immune system to eradicate cancer and can produce durable disease control that results in long-term, treatment-free survival in some patients. These drugs have shown very impressive survival in patients with BRAF-mutated melanoma. Thus, there is a need to continue to utilize emerging data to achieve long-term disease control for patients with advanced melanoma. Combining targeted therapy with immune therapy may be one possible way to achieve this goal. In this review, the mechanisms of action of these two pathways, including the mechanistic basis of this combination, are summarized, along with results of completed and ongoing trials in triple therapy.

CB-RAF600E-1 exerts efficacy in vemurafenib-resistant and non-resistant-melanoma cells via dual inhibition of RAS/RAF/MEK/ERK and PI3K/Akt signaling pathways

Background and Aim

Predicting novel dual inhibitors to combat adverse effects such as the development of resistance to vemurafenib in melanoma treatment due to the reactivation of MAPK and PI3K/AKT signaling pathways is studied to help in reversal of cancer symptoms.

Reversal of cancer symptoms in melanoma associated with vemurafenib resistance is driven by reactivation of MAPK and PI3K/Akt signaling pathways. Novel dual inhibitors targeting these proteins would be beneficial to combat resistance.

Methods

High-throughput virtual screening of the ChemBridge library against B-RAFV600E and Akt was performed using an automated protocol with the AutoDock VINA program. Luminescence and time-resolved fluorescence kits were used to measure enzyme activities. The MTT assay was used to determine proliferation in normal and vemurafenib-resistant A375 cells. Flow cytometry was used to examine apoptosis, cell cycle, and phosphorylation of ERK/Akt signaling pathway.

Results

High-throughput screening from the ChemBridge library identified 15 compounds with high binding energy towards B-RAFV600E; among these, CB-RAF600E-1 had the highest ΔG_binding score −11.9 kcal/mol. The compound also had a high affinity towards Akt, with a ΔG_binding score of −11.5 kcal/mol. CB-RAF600E-1 dose-dependently inhibited both B-RAFV600E and Akt with IC₅₀ values of 635 nM and 154.3 nM, respectively. The compound effectively controlled the proliferations of normal and vemurafenib-resistant A375 cells, with GI₅₀ values of 222.3 nM and 230.5 nM, respectively. A dose-dependent increase in the sub G₀/G₁ phase of the cell cycle and total apoptosis was observed following compound treatment in both normal and vemurafenib-resistant melanoma cells. Treatment with CB-RAF600E-1 decreased the pERK/pAkt dual-positive populations in normal and vemurafenib-resistant A375 cells.

Conclusion

CB-RAF600E-1, identified as a novel dual inhibitor effective against normal and vemurafenib-resistant melanoma cells, requires further attention for development as an effective chemotherapeutic agent for melanoma management.

The α-melanocyte-stimulating hormone/melanocortin-1 receptor interaction: A driver of pleiotropic effects beyond pigmentation

Melanocortin-1 Receptor (MC1R), when stimulated by alpha-melanocyte-stimulating hormone (α-MSH), is a driver of eumelanogenesis. Brown/black eumelanin is an effective filter against ultraviolet radiation (UVR) and is a scavenger of free radicals. Several polymorphic variants of MC1R are frequent in red-head people. These polymorphisms reduce the ability of MC1R to promote eumelanogenesis after its activation and spontaneous pheomelanogenesis take place. Since pheomelanin can act as an endogenous photosensitizer, people carrying MC1R polymorphisms are more susceptible to skin cancer. Here, we summarize current knowledge on the biology of MC1R beyond its ability to drive eumelanogenesis. We analyze its capacity to cope with oxidative insult and consequent DNA damage. We describe its ability to transduce through different pathways. We start from the canonical pathway, the cAMP/protein kinase A (PKA) pathway mainly involved in promoting eumelanogenesis, and protection from oxidative damage, and we then move on to describe more recent knowledge concerning ERK pathways, phosphoinositide 3-kinase (PI3K) pathway/AKT, and α-MSH/Peroxisome proliferators activated receptor-γ (PPAR-γ) connection. We describe MC1R polymorphic variants associated with melanoma risk which represent an open window of clinical relevance.

Whole-Exome Sequencing Reveals Novel Variations in Patients with Familial Von Hippel-Lindau Syndrome

OBJECTIVE

Von Hippel-Lindau (VHL) syndrome is a rare disease that occurs in an autosomal-dominant genetic pattern. Due to the high genetic variability of VHL diseases, current studies have limited clinical value. Moreover, casual genetic variations in patients with VHL syndrome are still unclear.

METHODS

Here, we performed whole-exome sequencing of 25 individuals to identify reliable disease-related variations. Systemic computational analysis was performed for variant detection, and Sanger sequencing was used to validate detected mutations.

RESULTS

Most of the known mutations in the VHL gene were observed in the studied population. In addition, a large fragment deletion in VHL exon 2 in the immediate family members of the last family was detected. This had not been reported earlier. Moreover, we identified 3 novel mutation sites in the MAP2K3 gene that may be involved in the occurrence and development of the VHL disease.

CONCLUSIONS

These results demonstrated that the heterogeneous nature of VHL syndrome and novel mutational signatures may help to improve the diagnostic ability of VHL syndrome.

From Melanoma Development to RNA-Modified Dendritic Cell Vaccines: Highlighting the Lessons From the Past

Although melanoma remains the deadliest skin cancer, the current treatment has not resulted in the desired outcomes. Unlike chemotherapy, immunotherapy has provided more tolerable approaches and revolutionized cancer therapy. Although dendritic cell-based vaccines have minor side effects, the undesirable response rates of traditional approaches have posed questions about their clinical translation. The immunosuppressive tumor microenvironment can be the underlying reason for their low response rates. Immune checkpoints and indoleamine 2,3-dioxygenase have been implicated in the induction of immunosuppressive tumor microenvironment. Growing evidence indicates that the mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase/Protein kinase B (PKB) (PI3K/AKT) pathways, as the main oncogenic pathways of melanoma, can upregulate the tumoral immune checkpoints, like programmed death-ligand 1. This study briefly represents the main oncogenic pathways of melanoma and highlights the cross-talk between these oncogenic pathways with indoleamine 2,3-dioxygenase, tumoral immune checkpoints, and myeloid-derived suppressor cells. Moreover, this study sheds light on a novel tumor antigen on melanoma, which has substantial roles in tumoral immune checkpoints expression, indoleamine 2,3-dioxygenase secretion, and stimulating the oncogenic pathways. Finally, this review collects the lessons from the previous unsuccessful trials and integrates their lessons with new approaches in RNA-modified dendritic cell vaccines. Unlike traditional approaches, the advances in single-cell RNA-sequencing techniques and RNA-modified dendritic cell vaccines along with combined therapy of the immune checkpoint inhibitors, indoleamine 2,3-dioxygenase inhibitor, and RNA-modified dendritic cell-based vaccine can overcome these auto-inductive loops and pave the way for developing robust dendritic cell-based vaccines with the most favorable response rate and the least side effects.

The Role of Systemic Therapy in Advanced Cutaneous Melanoma of the Head and Neck

The treatment of advanced melanoma has changed dramatically over the last decade. With the discovery of activating BRAF mutations and the development of targeted therapies and checkpoint inhibitors, the overall survival of patients with advanced melanoma has improved. This article provides an overview of systemic therapies, including the pivotal agents that have led to these advances.

Ferroptosis: a new unexpected chance to treat metastatic melanoma?

Human skin melanoma is one of the most aggressive and difficult to treat human malignancies, with an increasing incidence over the years. While the resection of the early diagnosed primary tumor remains the best clinical approach, advanced/metastatic melanoma still remains with a poor prognosis. Indeed, although enormous progress in the therapeutic treatment of human tumors has been made in recent years, patients affected by metastatic melanoma are still poorly affected by these clinical advances. Therefore, new valuable therapeutic approaches are urgently needed, to design and define effective treatments to consistently increase the overall survival rate of patients affected by this malignancy. In this review we summarize the main signaling pathways studied to kill human skin melanoma, and introduce the ferroptotic cell death as a new pathway to be explored to eradicate this tumor.

A Review of the Molecular Pathways Involved in Resistance to BRAF Inhibitors in Patients with Advanced-Stage Melanoma

Melanoma is an aggressive malignancy of melanocytes and most commonly arises in the skin. In 2002, BRAF gene mutations were identified in melanoma, and this finding resulted in the development of several small-molecule molecular inhibitors that specifically targeted the BRAF V600E mutation. The development of targeted therapies for advanced-stage melanoma, including tyrosine kinase inhibitors (TKIs) of the BRAF (V600E) kinase, vemurafenib and dabrafenib, have been approved for the treatment of advanced melanoma leading to improved clinical outcomes. However, the development of BRAF inhibitor (BRAFi) resistance has significantly reduced the therapeutic efficacy after prolonged treatment. Recent studies have identified the molecular mechanisms for BRAFi resistance. This review aims to describe the impact of BRAFi resistance on the pathogenesis of melanoma, the current status of molecular pathways involved in BRAFi resistance, including intrinsic resistance, adaptive resistance, and acquired resistance. This review will discuss how an understanding of the mechanisms associated with BRAFi resistance may aid the identification of useful strategies for overcoming the resistance to BRAF-targeted therapy in patients with advanced-stage melanoma.

Aldo-keto reductases protect metastatic melanoma from ER stress-independent ferroptosis

The incidence of melanoma is increasing over the years with a still poor prognosis and the lack of a cure able to guarantee an adequate survival of patients. Although the new immuno-based coupled to target therapeutic strategy is encouraging, the appearance of targeted/cross-resistance and/or side effects such as autoimmune disorders could limit its clinical use. Alternative therapeutic strategies are therefore urgently needed to efficiently kill melanoma cells. Ferroptosis induction and execution were evaluated in metastasis-derived wild-type and oncogenic BRAF melanoma cells, and the process responsible for the resistance has been dissected at molecular level. Although efficiently induced in all cells, in an oncogenic BRAF- and ER stress-independent way, most cells were resistant to ferroptosis execution. At molecular level we found that: resistant cells efficiently activate NRF2 which in turn upregulates the early ferroptotic marker CHAC1, in an ER stress-independent manner, and the aldo-keto reductases AKR1C1 ÷ 3 which degrades the 12/15-LOX-generated lipid peroxides thus resulting in ferroptotic cell death resistance. However, inhibiting AKRs activity/expression completely resensitizes resistant melanoma cells to ferroptosis execution. Finally, we found that the ferroptotic susceptibility associated with the differentiation of melanoma cells cannot be applied to metastatic-derived cells, due to the EMT-associated gene expression reprogramming process. However, we identified SCL7A11 as a valuable marker to predict the susceptibility of metastatic melanoma cells to ferroptosis. Our results identify the use of pro-ferroptotic drugs coupled to AKRs inhibitors as a new valuable strategy to efficiently kill human skin melanoma cells.

Dual BRAF/MEK therapy in BRAF V600E-mutated primary brain tumors: a case series showing dramatic clinical and radiographic responses and a reduction in cutaneous toxicity

OBJECTIVE

BRAF V600E is a common oncogenic driver in a variety of primary brain tumors. Dual inhibitor therapy using dabrafenib (a selective oral inhibitor of several mutated forms of BRAF kinase) and trametinib (a reversible inhibitor of MEK1 and MEK2) has been used successfully for treatment of metastatic melanoma, anaplastic thyroid cancer, and other tumor types, but has been reported in only a few patients with primary brain tumors and none with pleomorphic xanthoastrocytoma. Here, the authors report on the substantial clinical response and reduction in cutaneous toxicity in a case series of BRAF V600E primary brain cancers treated with dual BRAF/MEK inhibitor therapy.

METHODS

The authors treated 4 BRAF V600E patients, each with a different type of primary brain tumor (pilocytic astrocytoma, papillary craniopharyngioma, ganglioglioma, and pleomorphic xanthoastrocytoma) with the combination of dabrafenib and trametinib.

RESULTS

The patients with pilocytic astrocytoma, pleomorphic xanthoastrocytoma, and papillary craniopharyngioma experienced near-complete radiographic and complete clinical responses after 8 weeks of therapy. A substantial partial response (by RANO [Response Assessment in Neuro-Oncology] criteria) was observed in the patient with ganglioglioma. The patient with craniopharyngioma developed dramatic, diffuse verrucal keratosis within 2 weeks of starting dabrafenib. This completely resolved within 2 weeks of adding trametinib.

CONCLUSIONS

Dual BRAF/MEK inhibitor therapy represents an exciting treatment option for patients with BRAF V600E primary brain tumors. In addition to greater efficacy than single-agent dabrafenib, this combination has the potential to mitigate cutaneous toxicity, one of the most common and concerning BRAF inhibitor-related adverse events.

Discoidin domain receptors: A promising target in melanoma

The discoidin domain receptor 1 (DDR1) is a member of the receptor tyrosine kinase family that signals in response to collagen and that has been implicated in cancer progression. In the present study, we investigated the expression and role of DDR1 in human melanoma progression. Immunohistochemical staining of human melanoma specimens (n = 52) shows high DDR1 expression in melanoma lesions that correlates with poor prognosis. DDR1 expression was associated with the clinical characteristics of Clark level and ulceration and with BRAF mutations. Downregulation of DDR1 by small interfering RNA (siRNA) in vitro inhibited melanoma cells malignant properties, migration, invasion, and survival in several human melanoma cell lines. A DDR tyrosine kinase inhibitor (DDR1-IN-1) significantly inhibited melanoma cell proliferation in vitro, and ex vivo and in tumor xenografts, underlining the promising potential of DDR1 inhibition in melanoma.

Antitumor activity of ginsenoside Rg3 in melanoma through downregulation of the ERK and Akt pathways

Advanced metastatic melanoma is a malignant tumor for which there is currently no effective treatment due to resistance development. Ginsenoside Rg3, a saponin component extracted from ginseng roots, has been shown to reduce melanoma cell proliferation by decreasing histone deacetylase 3 and increasing p53 acetylation. The availability of data on the role of Rg3 in melanoma is currently extremely limited. The aim of the present study was to further investigate the effects of Rg3 on B16 melanoma cells and the underlying molecular events. The findings demonstrated that Rg3 suppressed the proliferation and DNA synthesis of B16 cells. Rg3 exposure induced tumor cell cycle arrest at the S phase and reduced the expression of proliferating cell nuclear antigen (PCNA). Rg3 treatment also decreased metastasis of B16 cells in vitro and in vivo. The results indicated that this reduction was due to downregulation of matrix metalloproteinase (MMP)-2 and MMP-9. Moreover, Rg3 inhibited melanoma-induced angiogenesis, most likely by downregulating vascular endothelial growth factor (VEGF) in B16 cells. Rg3 exposure decreased the expression of VEGF in B16 cells and the VEGF downregulation further suppressed angiogenesis by attenuating the proliferation and migration of vascular endothelial cells. Finally, the western blotting data demonstrated that Rg3 reduced the expression of extracellular signal-regulated kinase (ERK) and protein kinase B (Akt) in vitro and in vivo. This result indicated that the antimelanoma effects of Rg3 may be mediated through suppression of ERK and Akt signaling. Further research is required to assess the value of Rg3 as a novel therapeutic strategy for melanoma in the clinical setting.

Detection of BRAFV600E Mutation in Melanoma Patients by Digital PCR of Circulating DNA

AIMS

About 50% of melanomas have the BRAFV600E mutation. This mutation is an attractive therapeutic target. The aims of our study were to detect BRAFV600E mutations within circulating cell-free DNA in plasma ("liquid biopsy") by a droplet digital PCR (ddPCR) method, and to investigate how well the Breslow-Clark score can be predicted by ddPCR.

MATERIALS AND METHODS

We analyzed 113 patients with malignant melanoma. ddPCR was performed using the QX200 system (BIO-RAD^®, Hercules). All samples were tested in duplicate. Besides the results of the liquid biopsy, we have collected data on gender and age of the patients, as well as the mitotic activity of the tumor; the tumor subtype and localization, and the Breslow-Clark score. The limit of detection (LoD) was determined by the method of Tzonev. The LoD was found to be five events per well.

RESULTS

The BRAFV600E mutation was detected in 37 of 113 samples. A moderate predictive accuracy of the Breslow-Clark score can be attained with the mitotic activity and the type of melanoma as the most important predictors.

CONCLUSION

Our results show that ddPCR is a highly sensitive method and could be used for a routine laboratory detection of the BRAFV600E mutation as well as for follow-up monitoring to determine the treatment response in patients with malignant melanomas.

Cutaneous Side Effects of Targeted Therapy and Immunotherapy for Advanced Melanoma

Melanoma is one of the most fatal cancers, and its incidence is increasing worldwide. Thanks to the better understanding of the molecular mechanisms involved in the pathogenesis of melanoma, recently new targeted agents have been developed. In this article, we review the current state of knowledge of clinical presentation, mechanisms, and management of the most common cutaneous side effects observed during treatment with targeted and immunological therapies approved for advanced melanoma. We include discussion of BRAF/MEK inhibitors and immune-checkpoint inhibitors, notably CTLA-4 and PD-1 inhibitors.

The Power of Fish Models to Elucidate Skin Cancer Pathogenesis and Impact the Discovery of New Therapeutic Opportunities

Animal models play important roles in investigating the pathobiology of cancer, identifying relevant pathways, and developing novel therapeutic tools. Despite rapid progress in the understanding of disease mechanisms and technological advancement in drug discovery, negative trial outcomes are the most frequent incidences during a Phase III trial. Skin cancer is a potential life-threatening disease in humans and might be medically futile when tumors metastasize. This explains the low success rate of melanoma therapy amongst other malignancies. In the past decades, a number of skin cancer models in fish that showed a parallel development to the disease in humans have provided important insights into the fundamental biology of skin cancer and future treatment methods. With the diversity and breadth of advanced molecular genetic tools available in fish biology, fish skin cancer models will continue to be refined and expanded to keep pace with the rapid development of skin cancer research. This review begins with a brief introduction of molecular characteristics of skin cancers, followed by an overview of teleost models that have been used in the last decades in melanoma research. Next, we will detail the importance of the zebrafish (Danio rerio) animal model and other emerging fish models including platyfish (Xiphophorus sp.), and medaka (Oryzias latipes) in future cutaneous malignancy studies. The last part of this review provides the recent development and genome editing applications of skin cancer models in zebrafish and the progress in small molecule screening.

Effect of ABT-888 on the apoptosis, motility and invasiveness of BRAFi-resistant melanoma cells

Melanoma is a molecularly heterogeneous disease with many genetic mutations and altered signaling pathways. Activating mutations in the BRAF oncogene are observed in approximately 50% of cutaneous melanomas and the use of BRAF inhibitor (BRAFi) compounds has been reported to improve the outcome of patients with BRAF-mutated metastatic melanoma. However, the majority of these patients develop resistance within 6-8 months following the initiation of BRAFi treatment. In this study, we examined the possible use of the poly(ADP-ribose) polymerase 1 (PARP1) inhibitor, ABT-888 (veliparib), as a novel molecule that may be successfully employed in the treatment of BRAFi-resistant melanoma cells. Sensitive and resistant to BRAFi dabrafenib A375 cells were exposed to increasing concentrations of ABT-888. Cell viability and apoptosis were assessed by MTT assay and Annexin V-FITC analysis, respectively. The cell migratory and invasive ability was investigated using the xCELLigence technology and Boyden chamber assays, respectively. ABT-888 was found to reduce cell viability and exhibited pro-apoptotic activity in melanoma cell lines, independently from the BRAF/NRAS mutation status, in a dose-dependent manner, with the maximal effect being reached in the 25-50 µM concentration range. Moreover, ABT-888 promoted apoptosis in both the sensitive and resistant A375 cells, suggesting that ABT-888 may be useful in the treatment of BRAFi-resistant subsets of melanoma cells. Finally, in accordance with the involvement of PARP1 in actin cytoskeletal machinery, we found that the cytoskeletal organization, motility and invasive capability of both the A375 and A375R cells decreased upon exposure to 5 µM ABT-888 for 24 h. On the whole, the findings of this study highlight the pivotal role of PARP1 in the migration and invasion of melanoma cells, suggesting that ABT-888 may indeed be effective, not only as a pro-apoptotic drug for use in the treatment of BRAFi-resistant melanoma cells, but also in suppressing their migratory and invasive activities.

The Ashitaba (Angelica keiskei) Chalcones 4-hydroxyderricin and Xanthoangelol Suppress Melanomagenesis By Targeting BRAF and PI3K

Malignant melanoma is an aggressive tumor of the skin and still lacks effective preventive and therapeutic treatments. In melanoma, both the BRAF/MEK/ERK and PI3-K/AKT signaling pathways are constitutively activated through multiple mechanisms, which result in cell-cycle progression and prevention of apoptosis. Therefore, the development of novel strategies for targeting BRAF and PI3K are of utmost importance. In this study, we found that Ashitaba (Angelica keiskei) chalcones, 4-hydroxyderricin (4HD) and xanthoangelol (XAG), suppressed melanoma development by directly targeting both BRAFV600E and PI3K, which blocked the activation of downstream signaling. This led to the induction of G₁ phase cell-cycle arrest and apoptosis in melanoma cells. Importantly, 4HD or XAG dramatically attenuated tumor incidence and volume in the BRAF-activated Pten-deficient melanoma mouse model. Our findings suggest that 4HD and XAG are promising chemopreventive or potential therapeutic agents against melanomagenesis that act by targeting both BRAF and PI3K, providing hope for rapid clinical translation. Cancer Prev Res; 11(10); 607-20. ©2018 AACR.

Dabrafenib Treatment in a Patient with an Epithelioid Glioblastoma and BRAF V600E Mutation

Novel therapeutic targets in malignant glioma patients are urgently needed. Point mutations of the v-Raf murine sarcoma viral oncogene homolog B (BRAF) gene occur predominantly in melanoma patients, but may also occur in gliomas. Thus, this is a target of great interest for this group of patients. In a nine-year-old male patient, an anaplastic astrocytoma in the left temporoparietal region was diagnosed histologically. After first- and second-line treatment, a malignant progression to a secondary glioblastoma was observed ten years after the initial diagnosis. Within the following seven years, all other conventional treatment options were exhausted. At this time point, recurrent tumor histology revealed an epithelioid glioblastoma, without a mutation in the isocitrate dehydrogenase gene (IDH wild-type). In order to identify a potential target for an experimental salvage therapy, mutational tumor analysis showed a BRAF V600E mutation. Consecutively, dabrafenib treatment was initiated. The patient remained clinically stable, and follow-up magnetic resonance images (MRI) were consistent with “Stable Disease” according to the Response Assessment in Neuro-Oncology Working Group (RANO) criteria for the following ten months until tumor progression was detected. The patient died 16 months after dabrafenib treatment initiation. Particularly in younger glioma patients as well as in patients with an epithelioid glioblastoma, screening for a V600E BRAF mutation is promising since, in these cases, targeted therapy with BRAF inhibitors seems to be a useful salvage treatment option.

The anti-apoptotic BAG3 protein is involved in BRAF inhibitor resistance in melanoma cells

BAG3 protein, a member of BAG family of co-chaperones, has a pro-survival role in several tumour types. BAG3 anti-apoptotic properties rely on its characteristic to bind several intracellular partners, thereby modulating crucial events such as apoptosis, differentiation, cell motility, and autophagy. In human melanomas, BAG3 positivity is correlated with the aggressiveness of the tumour cells and can sustain IKK-γ levels, allowing a sustained activation of NF-κB. Furthermore, BAG3 is able to modulate BRAFV600E levels and activity in thyroid carcinomas. BRAFV600E is the most frequent mutation detected in malignant melanomas and is targeted by Vemurafenib, a specific inhibitor found to be effective in the treatment of advanced melanoma. However, patients with BRAF-mutated melanoma may result insensitive ab initio or, mostly, develop acquired resistance to the treatment with this molecule. Here we show that BAG3 down-modulation interferes with BRAF levels in melanoma cells and sensitizes them to Vemurafenib treatment. Furthermore, the down-modulation of BAG3 protein in an in vitro model of acquired resistance to Vemurafenib can induce sensitization to the BRAFV600E specific inhibition by interfering with BRAF pathway through reduction of ERK phosphorylation, but also on parallel survival pathways. Future studies on BAG3 molecular interactions with key proteins responsible of acquired BRAF inhibitor resistance may represent a promising field for novel multi-drugs treatment design.

MEK inhibitors induce Akt activation and drug resistance by suppressing negative feedback ERK-mediated HER2 phosphorylation at Thr701

Targeting the MEK/ERK pathway has been viewed as a promising strategy for cancer therapy. However, MEK inhibition leads to the compensatory PI3K/AKT activation and thus contributes to the desensitization of cancer cells to MEK inhibitors. The underlying molecular mechanism of this event is not yet understood. In this study, our data showed that the induction of Akt activity by MEK inhibitors was specifically observed in HER2‐positive breast cancer cells. Silence of HER2, or overexpression of HER2 kinase‐dead mutant, prevents the induction of Akt activation in response to MEK inhibition, indicating HER2 as a critical regulator for this event. Furthermore, HER2 Thr701 was demonstrated as a direct phosphorylation target of ERK1/2. Inhibition of this specific phosphorylation prolonged the dimerization of HER2 with EGFR in a clathrin‐dependent manner, leading to the enhanced activation of HER2 and EGFR tyrosine kinase and their downstream Akt pathway. These results suggest that suppression of ERK‐mediated HER2 Thr701 phosphorylation contributes to MEK inhibitor‐induced Akt activation.

MC1R signaling. Intracellular partners and pathophysiological implications

The melanocortin-1 receptor (MC1R) preferentially expressed in melanocytes is best known as a key regulator of the synthesis of epidermal melanin pigments. Its paracrine stimulation by keratinocyte-derived melanocortins also activates DNA repair pathways and antioxidant defenses to build a complex, multifaceted photoprotective response. Many MC1R actions rely on cAMP-dependent activation of two transcription factors, MITF and PGC1α, but pleiotropic MC1R signaling also involves activation of mitogen-activated kinases and AKT. MC1R partners such as β-arrestins, PTEN and the E3 ubiquitin ligase MGRN1 differentially regulate these pathways. The MC1R gene is complex and polymorphic, with frequent variants associated with skin phenotypes and increased cancer risk. We review current knowledge of signaling from canonical MC1R, its splice isoforms and natural polymorphic variants. Recently discovered intracellular targets and partners are also discussed, to highlight the diversity of mechanisms that may contribute to normal and pathological variation of pigmentation and sensitivity to solar radiation-induced damage. This article is part of a Special Issue entitled: Melanocortin Receptors - edited by Ya-Xiong Tao.

The recurrent architecture of tumour initiation, progression and drug sensitivity

Recent studies across multiple tumour types are starting to reveal a recurrent regulatory architecture in which genomic alterations cluster upstream of functional master regulator (MR) proteins, the aberrant activity of which is both necessary and sufficient to maintain tumour cell state. These proteins form small, hyperconnected and autoregulated modules (termed tumour checkpoints) that are increasingly emerging as optimal biomarkers and therapeutic targets. Crucially, as their activity is mostly dysregulated in a post-translational manner, rather than by mutations in their corresponding genes or by differential expression, the identification of MR proteins by conventional methods is challenging. In this Opinion article, we discuss novel methods for the systematic analysis of MR proteins and of the modular regulatory architecture they implement, including their use as a valuable reductionist framework to study the genetic heterogeneity of human disease and to drive key translational applications.

Proteomic profiling predicts drug response to novel targeted anticancer therapeutics

Most recently approved anti-cancer drugs by the US FDA are targeted therapeutic agents and this represents an important trend for future anticancer therapy. Unlike conventional chemotherapy that rarely considers individual differences, it is crucial for targeted therapies to identify the beneficial subgroup of patients for the treatment. Currently, genomics and transcriptomics are the major 'omic' analytics used in studies of drug response prediction. However, proteomic profiling excels both in its advantages of directly detecting an instantaneous dynamic of the whole proteome, which contains most current diagnostic markers and therapeutic targets. Moreover, proteomic profiling improves understanding of the mechanism for drug resistance and helps finding optimal combination therapy. This article reviews the recent success of applications of proteomic analytics in predicting the response to targeted anticancer therapeutics, and discusses the potential avenues and pitfalls of proteomic platforms and techniques used most in the field.

Autophosphorylation on S614 inhibits the activity and the transforming potential of BRAF

The BRAF proto-oncogene serine/threonine-protein kinase, known as BRAF, belongs to the RAF kinase family. It regulates the MAPK/ERK signalling pathway affecting several cellular processes such as growth, survival, differentiation, and cellular transformation. BRAF is mutated in ~8% of all human cancers with the V600E mutation constituting ~90% of mutations. Here, we have used quantitative mass spectrometry to map and compare phosphorylation site patterns between BRAF and BRAF V600E. We identified sites that are shared as well as several quantitative differences in phosphorylation abundance. The highest difference is phosphorylation of S614 in the activation loop which is ~5fold enhanced in BRAF V600E. Mutation of S614 increases the kinase activity of both BRAF and BRAF V600E and the transforming ability of BRAF V600E. The phosphorylation of S614 is mitogen inducible and the result of autophosphorylation. These data suggest that phosphorylation at this site is inhibitory, and part of the physiological shut-down mechanism of BRAF signalling.

Inhibition of Cell Proliferation in an NRAS Mutant Melanoma Cell Line by Combining Sorafenib and α-Mangostin

α-Mangostin is a natural product commonly used in Asia for cosmetic and medicinal applications including topical treatment of acne and skin cancer. Towards finding new pharmacological strategies that overcome NRAS mutant melanoma, we performed a cell proliferation-based combination screen using a collection of well-characterized small molecule kinase inhibitors and α-Mangostin. We found that α-Mangostin significantly enhances Sorafenib pharmacological efficacy against an NRAS mutant melanoma cell line. The synergistic effects of α-Mangostin and Sorafenib were associated with enhanced inhibition of activated AKT and ERK, induced ER stress, and reduced autophagy, eventually leading to apoptosis. The structure of α-Mangostin resembles several inhibitors of the Retinoid X receptor (RXR). MITF expression, which is regulated by RXR, was modulated by α-Mangostin. Molecular docking revealed that α-Mangostin can be accommodated by the ligand binding pocket of RXR and may thereby compete with RXR-mediated control of MITF expression. In summary, these data demonstrate an unanticipated synergy between α-Mangostin and sorafenib, with mechanistic actions that convert a known safe natural product to a candidate combinatorial therapeutic agent.

α-Mangostin, a Natural Agent, Enhances the Response of NRAS Mutant Melanoma to Retinoic Acid

BACKGROUND The identification and use of novel compounds alone or in combination hold promise for the fight against NRAS mutant melanoma. MATERIAL AND METHODS We screened a kinase-specific inhibitor library through combining it with α-Mangostin in NRAS mutant melanoma cell line, and verified the enhancing effect of α-Mangostin through inhibition of the tumorigenesis pathway. RESULTS Within the kinase inhibitors, retinoic acid showed a significant synergistic effect with α-Mangostin. α-Mangostin also can reverse the drug resistance of retinoic acid in RARa siRNA-transduced sk-mel-2 cells. Colony assay, TUNEL staining, and the expressions of several apoptosis-related genes revealed that a-Mangostin enhanced the effect of retinoic acid-induced apoptosis. The combination treatment resulted in marked induction of ROS generation and inhibition of the AKT/S6 pathway. CONCLUSIONS These results indicate that the combination of these novel natural agents with retinoid acid may be clinically effective in NRAS mutant melanoma.

Pustular psoriasis eruption with dabrafenib, a BRAF inhibitor

Targeted BRAF inhibition with vemurafenib and dabrafenib has dramatically improved the survival rate in metastatic melanoma. These agents are now being tested for their efficacy against other tumors with BRAF mutations, including lung adenocarcinoma. While cutaneous adverse events are prevalent with BRAF inhibition, our patient, to our knowledge, is the first to develop a psoriatic eruption with BRAF inhibitors. We postulate that the elevation of tumor necrosis factor-alpha (TNF-α) and the paradoxical activation of the mitogen-activated protein kinase (MAPK) pathway due to BRAF inhibition may be responsible for the eruption. More studies are needed to further elucidate the immunopathogenic mechanisms behind this adverse event. The response to MEK inhibitors and/or increased TNF-α inhibition may help support or debunk our hypothesis.

Registered Report: COT drives resistance to RAF inhibition through MAP kinase pathway reactivation

The Reproducibility Project: Cancer Biology seeks to address growing concerns about reproducibility in scientific research by conducting replications of selected experiments from a number of high-profile papers in the field of cancer biology. The papers, which were published between 2010 and 2012, were selected on the basis of citations and Altmetric scores (Errington et al., 2014). This Registered Report describes the proposed replication plan of key experiments from “COT drives resistance to RAF inhibition through MAPK pathway reactivation” by Johannessen and colleagues, published in Nature in 2010 (Johannessen et al., 2010). The key experiments to be replicated are those reported in Figures 3B, 3D-E, 3I, and 4E-F. In Figures 3B, D-E, RPMI-7951 and OUMS023 cells were reported to exhibit robust ERK/MEK activity concomitant with reduced growth sensitivity in the presence of the BRAF inhibitor PLX4720. MAP3K8 (COT/TPL2) directly regulated MEK/ERK phosphorylation, as the treatment of RPMI-7951 cells with a MAP3K8 kinase inhibitor resulted in a dose-dependent suppression of MEK/ERK activity (Figure 3I). In contrast, MAP3K8-deficient A375 cells remained sensitive to BRAF inhibition, exhibiting reduced growth and MEK/ERK activity during inhibitor treatment. To determine if RAF and MEK inhibitors together can overcome single-agent resistance, MAP3K8-expressing A375 cells treated with PLX4720 along with MEK inhibitors significantly inhibited both cell viability and ERK activation compared to treatment with PLX4720 alone, as reported in Figures 4E-F. The Reproducibility Project: Cancer Biology is collaboration between the Center for Open Science and Science Exchange and the results of the replications will be published in eLife.

DOI:http://dx.doi.org/10.7554/eLife.11414.001

The impact of sequencing on diagnosis and treatment of malignant melanoma

Melanoma is one of the clinically most important cancer types considering its high mortality rate and that it is commonly diagnosed in relatively young people. With the advent of targeted therapies and, more recently, immune checkpoint inhibitors, more treatment options are available resulting in higher patient survival rates. However, the successful application of these targeted therapies critically depends on the reliable detection of molecular aberrations. Today, massively parallel sequencing techniques enable us to analyze large sets of genes in a relatively short time. It has allowed increased knowledge of acquired somatic mutations in melanoma and has helped to identify new targets for personalized therapy, and potentially may help to predict response to immune therapies. Described here are the development of sequencing techniques, how their improvement has changed diagnosis, prognosis and management of malignant melanoma and the future perspectives of melanoma diagnostics in the routine clinical setting.

Specific immunohistochemical detection of the BRAF V600E mutation in primary and metastatic papillary thyroid carcinoma

PURPOSE

To evaluate the clinical value of immunohistochemistry (IHC) using anti-BRAF V600E antibody (clone VE1) for specific detection of the BRAF V600E mutant protein in formalin-fixed paraffin-embedded papillary thyroid carcinoma (PTC) specimens.

METHODS

A total of 118 PTC cases and 116 control cases processed between January 2008 and June 2010 were selected and created tissue microarrays (TMAs) for the study. BRAF V600E (VE1) IHC was performed on tissue sections from PTC cases to determine mutation status. Molecular tests (Sanger sequencing/ARMS) were used to confirm the BRAF V600E gene mutation in primary PTC.

RESULTS

A uniformly cytoplasmic staining throughout the tumors was observed in IHC-positive cases. BRAF V600E was detected in 68.6% (81/118) of PTC samples by IHC and in 61.9% (73/118) by Sanger sequencing/ARMS. The overall concordance between IHC and Sanger sequencing/ARMS was 93.2% (110/118). The sensitivity and specificity of the BRAF V600E IHC was 100% (73/73) and 82.2% (37/45), respectively. Positive and negative predictive values were 90.1% (73/81) and 100% (37/37), respectively. Expression of the BRAF V600E mutant protein was detected in all of 59 cases of primary carcinoma and corresponding metastatic carcinoma in lymph nodes. The concordance between IHC staining in primary and metastatic PTC was 100% (59/59).

CONCLUSION

IHC using VE1 antibody for detection of the BRAF V600E mutant protein expression in PTC showed high sensitivity and acceptable specificity, which are critical for diagnostic purposes. IHC staining for BRAF V600E showed uniformly cytoplasmic expression in both primary tumor and metastatic nodes. Therefore, IHC has high practical value for the detection of the BRAF V600E mutation in metastatic and primary PTC.

Chemotherapy for Melanoma

Prior to the recent therapeutic advances, chemotherapy was the mainstay of treatment options for advanced-stage melanoma. A number of studies have investigated various chemotherapy combinations in order to expand on the clinical responses achieved with single-agent dacarbazine, but these have not demonstrated an improvement in overall survival. Similar objective responses were observed with the combination of carboplatin and paclitaxel as were seen with single-agent dacarbazine. The combination of chemotherapy and immunotherapy, known as biochemo-therapy, has shown high clinical responses; however, biochemo-therapy has not been shown to improve overall survival and resulted in increased toxicities. In contrast, palliation and long-term responses have been observed with localized treatment with isolated limb perfusion or infusion in limb-isolated disease. Although new, improved therapeutic options exist for first-line management of advanced-stage melanoma, chemotherapy may still be important in the palliative treatment of refractory, progressive, and relapsed melanoma. We review the various chemotherapy options available for use in the treatment and palliation of advanced-stage melanoma, discuss the important clinical trials supporting the treatment recommendations, and focus on the clinical circumstances in which treatment with chemotherapy is useful.

Resistance to BRAF inhibitors induces glutamine dependency in melanoma cells

BRAF inhibitors can extend progression-free and overall survival in melanoma patients whose tumors harbor mutations in BRAF. However, the majority of patients eventually develop resistance to these drugs. Here we show that BRAF mutant melanoma cells that have developed acquired resistance to BRAF inhibitors display increased oxidative metabolism and increased dependency on mitochondria for survival. Intriguingly, the increased oxidative metabolism is associated with a switch from glucose to glutamine metabolism and an increased dependence on glutamine over glucose for proliferation. We show that the resistant cells are more sensitive to mitochondrial poisons and to inhibitors of glutaminolysis, suggesting that targeting specific metabolic pathways may offer exciting therapeutic opportunities to treat resistant tumors, or to delay emergence of resistance in the first-line setting.

BRAF and NRAS mutations are heterogeneous and not mutually exclusive in nodular melanoma

Inhibitors of RAF inhibit the MAPK pathway that plays an important role in the development and progression of those melanoma carrying the V600E BRAF mutation, but there’s a subset of such patients who do not respond to the therapy. Various mechanisms of drug resistance have been proposed which include the clonal heterogeneity of the tumor. We have studied a population of nodular melanoma to investigate the intratumor and intertumor heterogeneity by Laser Capture Microdissection (LCM) analysis. Our results showed that BRAF and NRAS mutations were detected in 47% and 33% of nodular melanoma, respectively, and that there is a discrepancy in mutational pattern of tumoral sample because in the 36% of patients a different mutation, in at least 1 area of the tumor, was found by LCM analysis, giving evidence of the presence of different clonal cells populations. Moreover, we found that mutations in BRAF and NRAS are not mutually exclusive because they were simultaneously present in the same tumor specimens and we observed that when the 2 different mutations were present one is a high-frequency mutation and the other is a low-frequency mutation. This was more evident in lymphonodal metastasis that resulted from wild type to mutational analysis, but showed different mutations following LCM analysis. Therefore, we believed that, when primary tumoral sample results negative to mutational analysis, if it is possible, metastases should be investigated to verify the presence of mutations. Generally, it should be searched for other mutations, in addition to BRAF V600E, so as to better understand the mechanism of drug resistance.

Histone Modifications, Modifiers and Readers in Melanoma Resistance to Targeted and Immune Therapy

The treatment of melanoma has been revolutionized by new therapies targeting MAPK signaling or the immune system. Unfortunately these therapies are hindered by either primary resistance or the development of acquired resistance. Resistance mechanisms involving somatic mutations in genes associated with resistance have been identified in some cases of melanoma, however, the cause of resistance remains largely unexplained in other cases. The importance of epigenetic factors targeting histones and histone modifiers in driving the behavior of melanoma is only starting to be unraveled and provides significant opportunity to combat the problems of therapy resistance. There is also an increasing ability to target these epigenetic changes with new drugs that inhibit these modifications to either prevent or overcome resistance to both MAPK inhibitors and immunotherapy. This review focuses on changes in histones, histone reader proteins and histone positioning, which can mediate resistance to new therapeutics and that can be targeted for future therapies.