RTK Inhibitors in Melanoma: From Bench to Bedside

Design and synthesis of antiproliferative 2-oxoindolin-3-ylidenes incorporating urea function with potential VEGFR-2 inhibitory properties

Targeted therapy is preferable over other therapeutics due to its limitation of drawbacks and better pharmaceutical outcomes. VEGF and its receptors have been observed to be hyper-activated in many cancer types and are considered promising targets for assigning anticancer agents. The current study is directed towards synthesis of novel antiproliferative 2-oxoindolin-3-ylidenes incorporating urea function with VEGFR-2 properties. The targeted agents were obtained through a two-step reaction. Addition of the appropriate 1-(acetylphenyl)-3-phenylurea 9a,b to the corresponding isatin 10a-f in ethanol containing a quantitative amount of Et2NH followed by acidic dehydration (AcOH/HCl) afforded the targeted agents 12a-j. Promising antiproliferation properties (MTT assay) were observed for most of the synthesized agents against HCT116 (colon), MCF7 (breast) and PaCa2 (pancreatic) cancer cell lines relative to sunitinib. VEGFR-2 inhibitory properties are consistent with the antiproliferation properties exhibited against the tested cell lines. Compound 12b (R = 4-NHCONHPh, R' = H; % inhibition = 87.2) is the most promising/potent anti-VEGFR-2 agent synthesized with activity close to that of sunitinib (% inhibition = 89.4) at 10 μM. Molecular docking studies (PDB: 3WZE and 3AGD) support the antiproliferation effects against cancer cell lines tested with VEGFR-2 inhibitory properties. The results are consistent with collaboration of the pharmacophores considered (2-oxoindolyl heterocycle and urea) in improving the bio-properties.

Oncogenic RTKs sensitize cancer cells to ferroptosis via c-Myc mediated upregulation of ACSL4

Alteration or abnormal activation of RTKs have been recurrently observed and recognized as an important driving factor in the progression of many human cancers. Ferroptosis, an iron-dependent form of regulated necrosis triggered by the accumulation of lethal lipid peroxides on cell membranes, has been implicated in various tumor types. Here we reported that oncogenic RTKs/RAS/RAF/c-Myc axis promotes cancer cells to ferroptosis. Mechanistically, c-Myc binds to the promoter region of ACSL4 and promotes the expression of ACSL4, thereby sensitizes cells to ferroptosis. We further showed that RTKs/RAS/RAF promote ferroptosis by upregulating c-Myc mediated expression of ACSL4 in cancer cells. Notably, overexpression of RTKs enhances the vulnerability of melanoma to the ferroptosis inducer in mouse xenograft model. These findings may provide an attractive intervention strategy to target cancers with oncogenic activation of RTKs via a ferroptosis-inducing approach.

Expression of variant isoforms of the tyrosine kinase SYK differentially regulates cervical cancer progression through PI3K/AKT pathway

Invasion and metastasis are the main reasons for the poor prognosis of patients with cervical cancer(CC). SYK is closely related to tumor development. However, the functions of its two isoforms, SYK (L) or SYK (S), are not fully understood to date. In this study, we investigated their biologic functions and possible prognostic values in CC. qRT-PCR was performed to detect the expression of SYK and two variant isoforms in cervical cancer tissues and cells. The association of SYK(L) and SYK(S) with Clinical pathological parameters were evaluated. The migration and invasion was detected by scratch assay and transwell. Western blot was conducted to measure the changes of epithelial mesenchymal transition (EMT)-related markers and PI3K/AKT signaling pathway proteins in cervical cancer cells. LY294002 (inhibitor of PI3K/AKT pathway) and IGF-1 (activator of PI3K/AKT pathway) were applied to evaluate the contribution of PI3K/AKT signaling pathway in cervical cancer cells. The expression of SYK(S) in cervical cancer tissues was significantly higher than that of SYK(L). SYK(L) and SYK(S) were correlated with muscular infiltration, SYK(L) high expression had a better prognosis, whereas SYK(S) high expression predicted a worse disease outcome. Cox multivariate regression analysis demonstrated that SYK(L) expression was an independent prognostic factor. SYK(L) significantly inhibited the proliferation, migration and invasion, while SYK(S) showed the opposite effects. LY294002 blocked SYK (L) knockdown-induced enhancement of migration and invasion as well as the expression EMT-related markers, whereas IGF-1 rescued the decreased migration, invasion and EMT induced by SYK (S) knockdown. The results suggest that SYK(L) and SYK(S) are involved in the progression of cervical cancer through PI3K/AKT signaling pathway, and may serve as potential targets for clinical treatment of advanced cervical cancer.

Design and Synthesis of New Dihydropyrimidine Derivatives with a Cytotoxic Effect as Dual EGFR/VEGFR-2 Inhibitors

We developed and synthesized tetrahydropyrimidine derivatives as possible cytotoxic agents to inhibit EGFR and VEGFR-2 in the present study. Our study completely assesses the cytotoxic efficiency of pyrimidine-based derivatives 4-15 against various cancer cell lines, revealing derivatives 12 and 15 for their remarkable activity with GI50 values of 37 and 35 nM, respectively, when compared to the reference erlotinib (33 nM). In vitro enzyme assays showed that target compounds, particularly 12, 14, and 15, effectively inhibited EGFR and VEGFR-2. In vitro enzyme testing revealed that compound 15 was the most promising, with IC50 values of 84 and 3.50 nM for EGFR and VEGFR-2, respectively. Additionally, an in vitro assessment of the novel targets' apoptotic potential revealed that both pro-apoptotic and antiapoptotic behaviors were promising, indicating that the apoptotic induction pathway is a strongly proposed action method for the newly developed targets. Finally, molecular docking experiments are elaborately discussed to corroborate the exact binding interactions of the most active hybrids 12 and 15 with the EGFR and VEGFR-2 active sites.

Development of Personalized Strategies for Precisely Battling Malignant Melanoma

Melanoma is the most severe and fatal form of skin cancer, resulting from multiple gene mutations with high intra-tumor and inter-tumor molecular heterogeneity. Treatment options for patients whose disease has progressed beyond the ability for surgical resection rely on currently accepted standard therapies, notably immune checkpoint inhibitors and targeted therapies. Acquired resistance to these therapies and treatment-associated toxicity necessitate exploring novel strategies, especially those that can be personalized for specific patients and/or populations. Here, we review the current landscape and progress of standard therapies and explore what personalized oncology techniques may entail in the scope of melanoma. Our purpose is to provide an up-to-date summary of the tools at our disposal that work to circumvent the common barriers faced when battling melanoma.

Antineoplastic indole-containing compounds with potential VEGFR inhibitory properties

Cancer is one of the most significant health challenges worldwide. Various techniques, tools and therapeutics/materials have been developed in the last few decades for the treatment of cancer, together with great interest, funding and efforts from the scientific society. However, all the reported studies and efforts seem insufficient to combat the various types of cancer, especially the advanced ones. The overexpression of tyrosine kinases is associated with cancer proliferation and/or metastasis. VEGF, an important category of tyrosine kinases, and its receptors (VEGFR) are hyper-activated in different cancers. Accordingly, they are known as important factors in the angiogenesis of different tumors and are considered in the development of effective therapeutic approaches for controlling many types of cancer. In this case, targeted therapeutic approaches are preferable to the traditional non-selective approaches to minimize the side effects and drawbacks associated with treatment. Several indole-containing compounds have been identified as effective agents against VEGFR. Herein, we present a summary of the recent indolyl analogs reported within the last decade (2012-2023) with potential antineoplastic and VEGFR inhibitory properties. The most important drugs, natural products, synthesized potent compounds and promising hits/leads are highlighted. Indoles functionalized and conjugated with various heterocycles beside spiroindoles are also considered.

Augmenting MEK inhibitor efficacy in BRAF wild-type melanoma: synergistic effects of disulfiram combination therapy

BACKGROUND

MEK inhibitors (MEKi) were shown to be clinically insufficiently effective in patients suffering from BRAF wild-type (BRAF WT) melanoma, even if the MAPK pathway was constitutively activated due to mutations in NRAS or NF-1. Thus, novel combinations are needed to increase the efficacy and duration of response to MEKi in BRAF WT melanoma. Disulfiram and its metabolite diethyldithiocarbamate are known to have antitumor effects related to cellular stress, and induction of endoplasmic reticulum (ER) stress was found to synergize with MEK inhibitors in NRAS-mutated melanoma cells. Therefore, we investigated the combination of both therapeutics to test their effects on BRAF-WT melanoma cells and compared them with monotherapy using the MEKi trametinib.

METHODS

The effects of combined therapy with disulfiram or its metabolite diethyldithiocarbamate and the MEKi trametinib were evaluated in a series of BRAF-WT melanoma cell lines by measuring cell viability and apoptosis induction. Cytotoxicity was additionally assessed in 3D spheroids, ex vivo melanoma slice cultures, and in vivo xenograft mouse models. The response of melanoma cells to treatment was studied at the RNA and protein levels to decipher the mode of action. Intracellular and intratumoral copper measurements were performed to investigate the role of copper ions in the antitumor cytotoxicity of disulfiram and its combination with the MEKi.

RESULTS

Diethyldithiocarbamate enhanced trametinib-induced cytotoxicity and apoptosis induction in 2D and 3D melanoma culture models. Mechanistically, copper-dependent induction of oxidative stress and ER stress led to Janus kinase (JNK)-mediated apoptosis in melanoma cells. This mechanism was also detectable in patient-derived xenograft melanoma models and resulted in a significantly improved therapeutic effect compared to monotherapy with the MEKi trametinib.

CONCLUSIONS

Disulfiram and its metabolite represent an attractive pharmaceutical approach to induce ER stress in melanoma cells that potentiates the antitumor effect of MEK inhibition and may be an interesting candidate for combination therapy of BRAF WT melanoma.

Targeting Melanoma with a phytochemical pool: Tailing Makisterone C

BACKGROUND AND OBJECTIVE

According to World Health Organization, melanoma claims the lives of about 48000 people worldwide each year. The purpose of this study was to identify potential phytochemical pool from Diplazium esculentum against proteins that contribute to melanoma development.

METHODS

The research was carried to locate potentially bioactive molecules and conduct a theoretical analysis of active ingredients from DE to impact melanoma. Network pharmacology, pharmacokinetics, protein network interaction, gene enrichment, survival, and infiltration analysis were conducted. Furthermore, molecular docking and molecular dynamics simulation was carried out for makisterone C-MAPK1, MAPK3, and AKT1 complexes.

RESULTS

The potential phytochemical pool were identified (stigmast-5-en-3-ol, esculentic acid, rutin, and makisterone C) and based on network pharmacology and molecular docking studies, makisterone-C was proposed to be the most promising ingredient. Furthermore, the investigation revealed 14 genes as critical "hubs" involved in combating melanoma that are manipulated by the above-mentioned 4 active ingredients and modulate multiple signaling in melanoma development.

CONCLUSION

This study insights into the potential anti-melanoma effects of phytochemical pool from Diplazium esculentum using network pharmacology analysis, molecular docking, and simulation tailing makisterone C as a lead moiety and suggests the need for makisterone C further evaluation in intervening melanoma progression.

Novel biomolecules in targeted cancer therapy: a new approach towards precision medicine

Cancer is a major threat to human life around the globe, and the discovery of novel biomolecules continue to be an urgent therapeutic need that is still unmet. Precision medicine relies on targeted therapeutic strategies. Researchers are better equipped to develop therapies that target proteins as they understand more about the genetic alterations and molecules that cause progression of cancer. There has been a recent diversification of the sorts of targets exploited in treatment. Therapeutic antibody and biotechnology advancements enabled curative treatments to reach previously inaccessible sites. New treatment strategies have been initiated for several undruggable targets. The application of tailored therapy has been proven to have efficient results in controlling cancer progression. Novel biomolecules like SMDCs, ADCs, mABs, and PROTACS has gained vast attention in the recent years. Several studies have shown that using these novel technology helps in reducing the drug dosage as well as to overcome drug resistance in different cancer types. Therefore, it is crucial to fully untangle the mechanism and collect evidence to understand the significance of these novel drug targets and strategies. This review article will be discussing the importance and role of these novel biomolecules in targeted cancer therapies.

Combinations of EGFR and MET inhibitors reduce proliferation and invasiveness of mucosal melanoma cells

Mucosal melanoma (MM) is a very rare and aggressive type of cancer for which immunotherapy or targeted therapy such as BRAF/MEK inhibitors, used in cutaneous melanoma, usually fail. Due to our earlier experience showing the high effectiveness of epidermal growth factor receptor (EGFR) and hepatocyte growth factor receptor (MET) inhibitors in reducing the activation of the MAPK and PI3K/AKT signalling pathways, we aim to test whether these drugs would also be effective for mucosal melanoma. Cells representing two commercially available mucosal melanoma cell lines (GAK and HMVII) and one cell line obtained from a patient's vaginal melanoma were treated with MET or EGFR inhibitors, or combinations of these agents. The dual-inhibitor treatment strategy resulted in a decrease of cell proliferation, migration and invasion. Moreover, combinations of inhibitors led to reduction of pEGFR/EGFR and pMET/MET ratio and downregulation of PI3K/AKT and MEK/ERK1/2-based signalling pathways. Our findings indicate a potential therapeutic strategy based on EGFR and MET inhibitors in mucosal melanoma, which should be further evaluated in vivo and in clinical experiments. They also suggest that targeting multiple receptor tyrosine kinases may block signalling crosstalk and possibly delay the appearance of resistance to kinase inhibitors in mucosal melanoma cells.

Mechanism of immune escape mediated by receptor tyrosine kinase KIT in thyroid cancer

OBJECTIVE

Thyroid cancer (TC) is one of the fastest-growing malignant tumors. This study sought to explore the mechanism of immune escape mediated by receptor tyrosine kinase (KIT) in TC.

METHODS

The expression microarray of TC was acquired through the GEO database, and the difference analysis and Kyoto encyclopedia of genes and genomes pathway enrichment analysis were carried out. KIT levels in TC cell lines (K1/SW579/BCPAP) and human normal thyroid cells were detected using reverse transcription quantitative polymerase chain reaction and western blot analysis. TC cells were transfected with overexpressed (oe)-KIT and CD8+ T cells were cocultured with SW579 cells. Subsequently, cell proliferation, migration, and invasion abilities, CD8+ T cell proliferation, cytokine levels (interferon-γ [IFN-γ]/tumor necrosis factor-α [TNF-α]) were determined using colony formation assay, Transwell assays, flow cytometry, and enzyme-linked immunosorbent assay. The phosphorylation of MAPK pathway-related protein (ERK) was measured by western blot analysis. After transfection with oe-KIT, cells were treated with anisomycin (an activator of the MAPK pathway), and the protein levels of p-ERK/ERK and programmed death-ligand 1 (PD-L1) were detected.

RESULTS

Differentially expressed genes (N = 2472) were obtained from the GEO database. KIT was reduced in TC samples and lower in tumor cells than those in normal cells. Overexpression of KIT inhibited immune escape of TC cells. Specifically, the proliferation, migration, and invasion abilities of TC cells were lowered, the proliferation level of CD8+ T cells was elevated, and IFN-γ and TNF-α levels were increased. KIT inhibited the activation of the MAPK pathway in TC cells and downregulated PD-L1.

CONCLUSION

KIT suppressed immune escape of TC by blocking the activation of the MAPK pathway and downregulating PD-L1.

MET Receptor Tyrosine Kinase Inhibition Reduces Interferon-Gamma (IFN-γ)-Stimulated PD-L1 Expression through the STAT3 Pathway in Melanoma Cells

Melanoma is the leading cause of death from cutaneous malignancy. While targeted therapy and immunotherapy with checkpoint inhibitors have significantly decreased the mortality rate of this disease, advanced melanoma remains a therapeutic challenge. Here, we confirmed that interferon-gamma (IFN-γ)-induced PD-L1 expression in melanoma cell lines. This increased expression was down-regulated by the reduction in phosphorylated STAT3 signaling via MET tyrosine kinase inhibitor treatment. Furthermore, immunoprecipitation and confocal immunofluorescence microscopy analysis reveals MET and PD-L1 protein-protein interaction and colocalization on the cell surface membrane of melanoma cells. Together, these findings demonstrate that the IFN-γ-induced PD-L1 expression in melanoma cells is negatively regulated by MET inhibition through the JAK/STAT3 signaling pathway and establish the colocalization and interaction between an RTK and a checkpoint protein in melanoma cells.

Autophagy in BRAF-mutant cutaneous melanoma: recent advances and therapeutic perspective

Macroautophagy, hereafter referred to as autophagy, represents a highly conserved catabolic process that maintains cellular homeostasis. At present, the role of autophagy in cutaneous melanoma (CM) is still controversial, since it appears to be tumor-suppressive at early stages of malignant transformation and cancer-promoting during disease progression. Interestingly, autophagy has been found to be often increased in CM harboring BRAF mutation and to impair the response to targeted therapy. In addition to autophagy, numerous studies have recently conducted in cancer to elucidate the molecular mechanisms of mitophagy, a selective form of mitochondria autophagy, and secretory autophagy, a process that facilitates unconventional cellular secretion. Although several aspects of mitophagy and secretory autophagy have been investigated in depth, their involvement in BRAF-mutant CM biology has only recently emerged. In this review, we aim to overview autophagy dysregulation in BRAF-mutant CM, along with the therapeutic advantages that may arise from combining autophagy inhibitors with targeted therapy. In addition, the recent advances on mitophagy and secretory autophagy involvement in BRAF-mutant CM will be also discussed. Finally, since a number of autophagy-related non-coding RNAs (ncRNAs) have been identified so far, we will briefly discussed recent advances linking ncRNAs to autophagy regulation in BRAF-mutant CM.

The benefit of co-targeting PARP-1 and c-Met on the efficacy of radiotherapy in wild type BRAF melanoma

Melanoma is known to be a radioresistant cancer. Melanoma radioresistance can be due to several factors such as pigmentation, antioxidant defenses and high Deoxyribonucleic acid (DNA) repair efficacy. However, irradiation induces intracellular translocation of RTKs, including cMet, which regulates response to DNA damage activating proteins and promotes DNA repair. Accordingly, we hypothesized that co-targeting DNA repair (PARP-1) and relevant activated RTKs, c-Met in particular, may radiosensitize wild-type B-Raf Proto-Oncogene, Serine/Threonine Kinase (WTBRAF) melanomas where RTKs are often upregulated. Firstly, we found that PARP-1 is highly expressed in melanoma cell lines. PARP-1 inhibition by Olaparib or its KO mediates melanoma cell sensitivity to radiotherapy (RT). Similarly, specific inhibition of c-Met by Crizotinib or its KO radiosensitizes the melanoma cell lines. Mechanistically, we show that RT causes c-Met nuclear translocation to interact with PARP-1 promoting its activity. This can be reversed by c-Met inhibition. Accordingly, RT associated with the inhibition of both c-Met and PARP-1 resulted in a synergistic effect not only on tumor growth inhibition but also on tumor regrowth control in all animals following the stop of the treatment. We thus show that combining PARP and c-Met inhibition with RT appears a promising therapeutic approach in WTBRAF melanoma.

Expression and Prognostic Evaluation of the Receptor Tyrosine Kinase MET in Canine Malignant Melanoma

The overexpression and activation of the MET receptor tyrosine kinase has been identified in many human malignancies, but its role in canine cancer has only been minimally investigated. In this study we evaluated the expression of MET in two canine malignant melanoma (CMM) cell lines as well as in 30 CMM tissue samples that were collected from the clinical service at our institution. We were able to confirm the expression of the MET protein in both melanoma cell lines, and we demonstrated MET activation by its ligand, HGF, through phosphorylation, in Western blot analysis. We were also able to demonstrate, by immunohistochemistry, the expression of MET in 63% of the tumor tissue samples analyzed, with the majority demonstrating a relatively low expression profile. We then evaluated the association of MET expression scores with histologic parameters, metastasis, and survival. While statistically significant associations were not found across these parameters, an inverse relationship between MET expression levels and time to lymph node versus distant metastasis was suggested in our cohort. These findings may require assessment in a larger group of specimens to further evaluate the role of MET expression in the homing of metastasis in lymph nodes versus that in distant organs.

To Investigate Growth Factor Receptor Targets and Generate Cancer Targeting Inhibitors

Receptor tyrosine kinase (RTK) regulates multiple pathways, including Mitogenactivated protein kinases (MAPKs), PI3/AKT, JAK/STAT pathway, etc. which has a significant role in the progression and metastasis of tumor. As RTK activation regulates numerous essential bodily processes, including cell proliferation and division, RTK dysregulation has been identified in many types of cancers. Targeting RTK is a significant challenge in cancer due to the abnormal upregulation and downregulation of RTK receptors subfamily EGFR, FGFR, PDGFR, VEGFR, and HGFR in the progression of cancer, which is governed by multiple RTK receptor signalling pathways and impacts treatment response and disease progression. In this review, an extensive focus has been carried out on the normal and abnormal signalling pathways of EGFR, FGFR, PDGFR, VEGFR, and HGFR and their association with cancer initiation and progression. These are explored as potential therapeutic cancer targets and therefore, the inhibitors were evaluated alone and merged with additional therapies in clinical trials aimed at combating global cancer.

New targeted and epigenetic therapeutic strategies for the treatment of uveal melanoma

Uveal melanoma (UM) is a rare, genetically bland ocular malignancy with excellent local treatment options, but no disease-specific therapies are approved for use in the metastatic setting by the Food and Drug Administration. Metastatic UM (mUM) confers a prognosis of ~15 months. Unlike cutaneous melanoma, UM is poorly responsive to checkpoint inhibitors and cytotoxic chemotherapy highlighting the importance of clarifying vulnerable disease-specific mechanisms, such as cell cycle or metabolic pathways necessary for tumor growth and survival. The elucidation of signaling pathways downstream of the frequently mutated GNA GTPase such as PKC/MAPK/ERK/MEK, PI3K/AKT, and YAP-Hippo have offered potential targets. Potentially druggable epigenetic targets due to BAP1-mutated UM have also been identified, including proteins involved with histone deacetylation and DNA splicing. This review describes the preclinical rationale for the development of targeted therapies and current strategies currently being studied in clinical trials or will be in the near future.

[Research progress on non-surgical treatment of vestibular schwannomas]

At present, the main treatment for vestibular schwannomas is surgery. Considering the risk of multiple complications from surgery and the subjective and objective conditions of patients, a non-surgical treatment modality, namely stereotactic radiotherapy, has gradually been included in the treatment of vestibular schwannomas. Studies have shown that Gamma Knife therapy has a more prominent therapeutic effect on smaller tumors and can alleviate facial nerve disorders caused by space occupying of tumor mass. Cyberknife not only has a better effect on tumor control, but also has an ideal retention rate for patients' auditory function. Proton beam therapy has also been gradually applied to the treatment of vestibular schwannomas, but the effect of treatment remains to be further studied. Drug therapy includes a variety of target inhibitors and anti-angiogenic drugs. At present, drug treatment focuses more on preclinical research. This article reviews the clinical research of various radiotherapy and the progress of drug treatment.

The future of targeted kinase inhibitors in melanoma

Melanoma is a cancer of the pigment-producing cells of the body and its incidence is rising. Targeted inhibitors that act against kinases in the MAPK pathway are approved for BRAF-mutant metastatic cutaneous melanoma and increase patients' survival. Response to these therapies is limited by drug resistance and is less durable than with immune checkpoint inhibition. Conversely, rare melanoma subtypes have few therapeutic options for advanced disease and MAPK pathway targeting agents show minimal anti-tumor effects. Nevertheless, there is a future for targeted kinase inhibitors in melanoma: in new applications such as adjuvant or neoadjuvant therapy and in novel combinations with immunotherapies or other targeted therapies. Pre-clinical studies continue to identify tumor dependencies and their corresponding actionable drug targets, paving the way for rational targeted kinase inhibitor combinations as a personalized medicine approach for melanoma.

Radiosynthesis and evaluation of [11C]AG-488, a dual anti-angiogenetic and anti-tubulin PET ligand

Combinations of antiangiogenic and cytotoxic agents show promising results in the treatment of cancer. However, there is a lack of single agent with both antiangiogenic and cytotoxic activities for clinical application. AG-488 aka FLAG-003 is a novel ligand with established antiangiogenetic properties via activation of receptor thymidine kinase (RTK) and anti-tubulin properties in tumor cells. AG-488 is also reported to reduce tumor volume and prolong survival in preclinical animal models of glioblastoma multiforme, breast cancer and is in clinical stage. Higher expression of RTKs and tubulins is reported in various cancers. This study reveals the development of [¹¹C]AG-488, a high affinity dual target inhibitor binding to RTK and anti-tubulin activities. We rationale that antiangiogenic RTK and anti-tubulin activity of [¹¹C]AG-488 may enhance the tumor to tissue ratio, assisting in cancer drug development. [¹¹C]AG-488 was synthesized in 35 ± 5 % radiochemical yield by radiomethylating the corresponding phenolate using [¹¹C]CH₃I. MicroPET studies in mice indicated blood-brain barrier penetration of [¹¹C]AG-488 and retention in the brain. However, blocking studies with antitubulin and RTK agent HD-800 and microtubule depolymerizing agent MPC-6827 show increased binding of [¹¹C]AG-488 in brain. The pattern of tracer binding in blocking conditions is similar to the baseline conditions. The higher binding may be due to the increased plasma uptake of radiotracer or the formation of more free tubulins due to microtubule dynamic instability during the blocking conditions.

Targeting EGFR in melanoma - The sea of possibilities to overcome drug resistance

Melanoma is considered one of the most aggressive skin cancers. It spreads and metastasizes quickly and is intrinsically resistant to most conventional chemotherapeutics, thereby presenting a challenge to researchers and clinicians searching for effective therapeutic strategies to treat patients with melanoma. The use of inhibitors of mutated serine/threonine-protein kinase B-RAF (BRAF), e.g., vemurafenib and dabrafenib, has revolutionized melanoma chemotherapy. Unfortunately, the response to these drugs lasts a limited time due to the development of acquired resistance. One of the proteins responsible for this process is epidermal growth factor receptor (EGFR). In this review, we summarize the role of EGFR signaling in the multidrug resistance of melanomas and discuss possible applications of EGFR inhibitors to overcome the development of drug resistance in melanoma cells during therapy.

Mechanistic Translation of Melanoma Genetic Landscape in Enriched Pathways and Oncogenic Protein-Protein Interactions

BACKGROUND/AIM

Malignant melanoma is a skin cancer originating from the oncogenic transformation of melanocytes located in the epidermal layers. Usually, the patient's prognosis depends on timing of disease detection and molecular and genetic profiling, which may all significantly influence mortality rates. Genetic analyses often detect somatic BRAF, NRAS and cKIT mutations, germline substitutions in CDKN2A, and alterations of the PI3K-AKT-PTEN pathway. A peculiar molecular future of melanoma is its high immunogenicity, making this tumor targetable by programmed cell death protein 1-specific antibodies.

MATERIALS AND METHODS

Ten formalin-fixed paraffin embedded samples derived from melanoma patients were subjected to next-generation sequencing (NGS) analysis using the FDA-approved FoundationOne CDx™ test. The molecular features of each case were then analyzed employing several in silico prediction tools.

RESULTS

We analyzed the mutational landscape of patients with metastatic or relapsed cutaneous melanoma to define enriched pathways and protein-protein interactions. The analysis showed that both known genetic alterations and variants of unknown significance rely on redundant signaling converging on similar gene ontology biological processes. Complex informatics analyses of NGS-based genetic results identified pivotal signaling pathways that could provide additional targets for cancer treatment.

CONCLUSION

Our data suggest an additional role for NGS in melanoma, as analysis of comprehensive genetic findings using innovative informatic tools may lengthen the list of druggable molecular targets that impact patient outcome.

Bioluminescent Zebrafish Transplantation Model for Drug Discovery

In the last decade, zebrafish have accompanied the mouse as a robust animal model for cancer research. The possibility of screening small-molecule inhibitors in a large number of zebrafish embryos makes this model particularly valuable. However, the dynamic visualization of fluorescently labeled tumor cells needs to be complemented by a more sensitive, easy, and rapid mode for evaluating tumor growth in vivo to enable high-throughput screening of clinically relevant drugs. In this study we proposed and validated a pre-clinical screening model for drug discovery by utilizing bioluminescence as our readout for the determination of transplanted cancer cell growth and inhibition in zebrafish embryos. For this purpose, we used NanoLuc luciferase, which ensured rapid cancer cell growth quantification in vivo with high sensitivity and low background when compared to conventional fluorescence measurements. This allowed us large-scale evaluation of in vivo drug responses of 180 kinase inhibitors in zebrafish. Our bioluminescent screening platform could facilitate identification of new small-molecules for targeted cancer therapy as well as for drug repurposing.

Understanding Molecular Mechanisms of Phenotype Switching and Crosstalk with TME to Reveal New Vulnerabilities of Melanoma

Melanoma cells are notorious for their high plasticity and ability to switch back and forth between various melanoma cell states, enabling the adaptation to sub-optimal conditions and therapeutics. This phenotypic plasticity, which has gained more attention in cancer research, is proposed as a new paradigm for melanoma progression. In this review, we provide a detailed and deep comprehensive recapitulation of the complex spectrum of phenotype switching in melanoma, the key regulator factors, the various and new melanoma states, and corresponding signatures. We also present an extensive description of the role of epigenetic modifications (chromatin remodeling, methylation, and activities of long non-coding RNAs/miRNAs) and metabolic rewiring in the dynamic switch. Furthermore, we elucidate the main role of the crosstalk between the tumor microenvironment (TME) and oxidative stress in the regulation of the phenotype switching. Finally, we discuss in detail several rational therapeutic approaches, such as exploiting phenotype-specific and metabolic vulnerabilities and targeting components and signals of the TME, to improve the response of melanoma patients to treatments.

3, 3'- (3, 5-DCPBC) Down-Regulates Multiple Phosphokinase Dependent Signal Transduction Pathways in Malignant Melanoma Cells through Specific Diminution of EGFRY1086 Phosphorylation

Melanoma is the most dangerous skin malignancy due to its strong metastatic potential with high mortality. Activation of crucial signaling pathways enforcing melanoma progression depends on phosphorylation of distinct tyrosine kinases and oxidative stress. We here investigated the effect of a bis-coumarin derivative [3, 3′- ((3″, 5′-Dichlorophenyl) methylene) bis (4-hydroxy-2H-chromen-2-one)] [3, 3′- (3, 5-DCPBC)] on human melanoma cell survival, growth, proliferation, migration, intracellular redox state, and deciphered associated signaling pathways. This derivative is toxic for melanoma cells and non-toxic for melanocytes, their benign counterpart, and fibroblasts. 3, 3′- (3, 5-DCPBC) inhibits cell survival, migration, and proliferation of different metastatic and non-metastatic melanoma cell lines through profound suppression of the phosphorylation of Epidermal Growth Factor receptor (EGFR) and proto-oncogene cellular sarcoma (c-SRC) related downstream pathways. Thus, 3, 3′- (3, 5-DCPBC) endowed with the unique property to simultaneously suppress phosphorylation of multiple downstream kinases, such as EGFR/JAK/STAT and EGFR/SRC and their corresponding transcription factors.

Plant-Derived Terpenoids: A Promising Tool in the Fight against Melanoma

Simple Summary

Despite the numerous therapies, melanoma remains the deadliest of all skin cancers; however, plant-derived terpenoids are defense molecules that have proven anti-cancer properties. In this review, we present the results of the search for anti-melanoma plant terpenoids. Additionally, we show the effects of combining terpenoids with standard drugs, radiation therapy, or other plant substances on melanoma cell lines and animal models. Finally, we present some examples of drug delivery systems that increase the uptake of terpenoids by melanoma tissue.

Abstract

Melanoma is responsible for the highest number of skin cancer-caused deaths worldwide. Despite the numerous melanoma-treating options, the fight against it remains challenging, mainly due to its great heterogeneity and plasticity, as well as the high toxicity of standard drugs. Plant-derived terpenoids are a group of plant defense molecules that have been proven effective in killing many different types of cancer cells, both in in vitro experiments and in vivo models. In this review, we focus on recent results in the search for plant terpenoids with anti-melanoma activity. We also report on the synergistic action of combining terpenoids with other plant-derived substances, MAP kinase inhibitors, or radiation. Additionally, we present examples of terpenoid-loaded nanoparticle carriers as anti-melanoma agents that have increased permeation through the cancer tissue.

Novel Inhibitor-Based Therapies for Thyroid Cancer-An Update

Thyroid cancers (TCs) are the most common tumors of the endocrine system and a constant rise in the number of TC cases has been observed for the past few decades. TCs are one of the most frequent tumors in younger adults, especially in women, therefore early diagnosis and effective therapy are especially important. Ultrasonography examination followed by fine needle biopsy have become the gold standard for diagnosis of TCs, as these strategies allow for early-stage detection and aid accurate qualification for further procedures, including surgical treatment. Despite all the advancements in detection and treatment of TCs, constant mortality levels are still observed. Therefore, a novel generation line of targeted treatment strategies is being developed, including personalized therapies with kinase inhibitors. Recent molecular studies on TCs demonstrate that kinase inhibitor-based therapies might be considered as the most promising. In the past decade, new kinase inhibitors with different mechanisms of action have been reported and approved for clinical trials. This review presents an up-to-date picture of new approaches and challenges of inhibitor-based therapies in treatment of TCs, focusing on the latest findings reported over the past two years.

Sorafenib treatment of metastatic melanoma with c-Kit aberration reduces tumor growth and promotes survival

Melanomas are highly malignant tumors that readily metastasize and have poor prognosis. Targeted therapy is a cornerstone of treatment for patients with melanoma. Although c-Kit gene aberration has found in 5-10% of melanoma cases, research on c-Kit inhibitors for melanoma with c-Kit aberration have been disappointing. Sorafenib is a tyrosine kinase inhibitor, whose targets include c-Kit, platelet derived growth factor receptor (PDGFR), VEGFR and RAF. The present study aimed to examine the effect of sorafenib on metastatic melanoma with c-Kit aberration. Cell viability was assessed via trypan blue assay. Migration and invasion were analyzed using cell culture inserts. The anti-metastatic effects and antitumour activity of sorafenib were determined in an in vivo model. Protein expression was detected via western blotting, and the expression of MMP and very late antigen (VLA) was detected via reverse transcription-quantitative PCR. It was identified that sorafenib decreased cell viability, migration and invasion in vitro. Furthermore, sorafenib inhibited metastasis and tumor growth in vivo. Mechanistically, sorafenib inhibited c-Kit, PDGFR, VEGFR, B-Raf and c-Raf phosphorylation both in vitro and in vivo. In addition, sorafenib reduced the expression levels of MMPs and VLA. Importantly, there was a significant effect of sorafenib treatment on overall survival in mice. Collectively, this study suggests that sorafenib may serve as a novel therapeutic option for melanoma with c-Kit dysregulation.

Structural Protein Analysis of Driver Gene Mutations in Conjunctival Melanoma

In recent years, there has been tremendous enthusiasm with respect to detailing the genetic basis of many neoplasms, including conjunctival melanoma (CM). We aim to analyze five proteins associated with CM, namely BRAF, NRAS, c-KIT, NF1, and PTEN. We evaluated each protein for its intrinsically disordered protein regions (IDPRs) and its protein-protein interactions (PPI) with the Predictor of Natural Disordered Protein Regions (PONDR^®) and the Search Tool for the Retrieval of Interacting Genes (STRING^®). Our PONDR^® analysis found high levels of IDPRs in all five proteins with mutations linked to CM. The highest levels of IDPRs were in BRAF (45.95%), followed by PTEN (31.76%), NF1 (22.19%), c-KIT (21.82%), and NRAS (14.81%). Our STRING analysis found that each of these five proteins had more predicted interactions then expected (p-value < 1.0 × 10⁻¹⁶). Our analysis demonstrates that the mutations linked to CM likely affected IDPRs and possibly altered their highly complex PPIs. Quantifying IDPRs in BRAF, NRAS, c-KIT, NF1, and PTEN and understanding these protein regions are important processes as IDPRs can be possible drug targets for novel targeted therapies for treating CM.