Genetics of metastasis: melanoma and other cancers

Novel insights into the pathogenesis and treatment of NRAS mutant melanoma

INTRODUCTION

NRAS was the first mutated oncogene identified in melanoma and is currently the second most common driver mutation in this malignancy. For patients with NRAS^mutant advanced stage melanoma refractory to immunotherapy or with contraindications to immune-based regimens, there are few therapeutic options including low-efficacy chemotherapy regimens and binimetinib monotherapy. Here, we review recent advances in preclinical studies of molecular targets for NRAS mutant melanoma as well as the failures and successes of early-phase clinical trials. While there are no targeted therapies for NRAS-driven melanoma, there is great promise in approaches combining MEK inhibition with inhibitors of the focal adhesion kinase (FAK), inhibitors of autophagy pathways, and pan-RAF inhibitors.

AREAS COVERED

This review surveys new developments in all aspects of disease pathogenesis and potential treatment - including those that have failed, stalled, or progressed through various phases of preclinical and clinical development.

EXPERT OPINION

There are no currently approved targeted therapies for BRAF wild-type melanoma patients harboring NRAS driver mutations though an array of agents are in early phase clinical trials. The diverse strategies taken exploit combined MAP kinase signaling blockade with inhibition of cell cycle mediators, inhibition of the autophagy pathway, and alteration of kinases involved in actin cytoskeleton signaling. Future advances of developmental therapeutics into late stage trials may yield new options beyond immunotherapy for patients with advanced stage disease and NRAS mutation status.

Identification of metastasis-related genes by genomic and transcriptomic studies in murine melanoma

AIMS

We systematically characterized metastatic murine B16-F10 melanoma, a sub-line derived from murine melanoma B16-F1 cells.

MATERIALS AND METHODS

RNA-sequencing and network analyses (Ingenuity Pathway Analysis) were performed to identify novel potential metastasis mechanisms. Chromosomal aberrations were identified by multicolor fluorescence in situ hybridization (mFISH) using all 21 murine whole chromosome painting probes.

KEY FINDINGS

Numerous genes were overexpressed in B16-F10 cells, some of which have been already described as being metastasis-linked. Nr5a1/sf1, a known prognostic marker for adrenal tumors, was 177-fold upregulated in B16-F10 cells compared to B16-F1 cells. Hoxb8 was 75-fold upregulated, which was previously associated with gastric cancer progression and metastasis. Ptk7, which is linked with tumorigenesis and metastasis of esophageal squamous carcinoma, was 67-fold upregulated. B16-F10 cells acquired additional chromosomal aberrations compared to B16-F1 cells, including dic(4)(pter->qter:qter->pter), +dic(6;15), +der(10)t(10;?1;16).

SIGNIFICANCE

In addition to well-known metastatic genes, numerous novel genes and genomic aberrations were identified, which may serve as targets for treatment in the future. Transcriptomic and genetic analyses in B16-F10 cells unraveled a range of novel metastasis mechanisms, which may also have important implications for future treatment strategies.

The positive correlation between drug addiction and drug dosage in vemurafenib-resistant melanoma cells is underpinned by activation of ERK1/2-FRA-1 pathway

Malignant melanoma is a kind of highly invasive and deadly diseases. The BRAF inhibitor (BRAFi) such as vemurafenib could achieve a high response rate in melanoma patients with BRAF mutation. However, melanoma cells could easily develop resistance as well as addiction to BRAFi. Based on the drug addiction, intermittent treatment has been proposed to select against BRAFi-resistant melanoma cells. Because different dosages of BRAFi might be used in patients, it is necessary to know about the relationship between drug dosage and the degree of addiction. To address the problem, four drug-resistant melanoma cell sublines (A375/R0.5, A375/R2.0, M14/R0.5 and M14/R2.0) were established by continuously exposure of melanoma A375 or M14 cells to 0.5 or 2.0 μM vemurafenib. Vemurafenib withdrawal resulted in much stronger suppression on clone formation in A375/R2.0 and M14/R2.0, compared with A375/R0.5 and M14/R0.5, respectively. Meanwhile, stronger upregulation of ERK1/2-FRA-1 pathway could be observed in A375/R2.0 and M14/R2.0. Further detection showed that some proinflammatory cytokines downstream of ERK1/2-FRA-1 pathway were upregulated after drug withdrawal, and the conditioned medium collected from the resistant A375 cells could inhibit clone formation. Furthermore, vemurafenib withdrawal resulted in suppressed cell proliferation rather than cell senescence, with stronger effect on A375/R2.0 compared with A375/R0.5. This study suggested that the depth of vemurafenib addiction in resistant melanoma cells is positively correlated to the drug dosage, which might be underpinned by the ERK1/2-FRA-1 pathway and the related cytokines.

Expression of P16INK4a in Uveal Melanoma: New Perspectives

Uveal melanoma (UM) is the most common intraocular tumor in adults. Despite sharing the name and similar morphological features with cutaneous melanoma (CM), it is an entirely different neoplasia with a particular genetic background and clinical behavior. CDKN2A is a gene located at chromosome 9p21, encoding for P16INK4a and P14(ARF) proteins, whose role as a tumor suppressor has been clearly defined in many malignant tumors. CDKN2A frequently presents germline mutations in familial CM and epigenetic downregulation in a considerable percentage of sporadic CM. It has been hypothesized that CDKN2A alterations are early events in CM development, playing a central role in the malignant transformation of melanocytes. Alterations of the CDKN2A gene reduce the expression of P16INK4a in most CM subtypes. Immunohistochemical evaluation of P16INK4a is currently used, in association with Ki67 and HMB45, in pathology practice to discriminate between dysplastic nevi and melanoma. On the other hand, CKDN2A is rarely mutated in UM, and the immunohistochemical expression of P16INK4a has only been reported in small case series. We tested P16INK4a expression on paraffin-embedded tissue sections from 9 tissue microarrays (TMAs), built with 2 mm cores derived from 133 uveal melanoma FFPE blocks, collected from 1990 to 2018, and from selected paraffin-blocks of 3 UM liver metastases. The immunohistochemical expression of P16INK4a was assessed with a visual evaluation by light microscopy and then with a digital approach. Both approaches, with an acceptable concordance rate, revealed P16INK4a expression in a large proportion of UM cases and all liver metastases, opening new possibilities of using it in the differential diagnosis between cutaneous and uveal melanoma metastases in cases of unknown primary tumor or patients with two different primary melanomas.

Hydrogen-Peroxide-Responsive Protein Biomimetic Nanoparticles for Photothermal-Photodynamic Combination Therapy of Melanoma

BACKGROUND AND OBJECTIVES

Recently, there has been a rapid increase in the incidences of melanoma, which represents a serious threat to human health. Generally, tumor-microenvironment-responsive nanoparticle-based photothermal-photodynamic combination therapy (PTT-PDT) is characterized by intratumoral response and tumor targeting. In this study, we designed and synthesized hydrogen-peroxide-responsive protein biomimetic nanoparticles (MnO₂ -ICG@BSA) for the treatment of melanoma.

STUDY DESIGN/MATERIALS AND METHODS

Briefly, MnO₂ -ICG@BSA was prepared using a mild protein synthesis method by loading indocyanine green (ICG) into a bovine serum albumin-manganese dioxide complex (MnO₂ @BSA); next, its characteristics were determined. In addition, in vitro biocompatibility and antitumor efficacy were assessed using the classic cell counting kit-8 assay. Moreover, in vivo high-frequency ultrasound and thermal imaging were used to evaluate the oxygen-production capacity and photothermal conversion effect of MnO₂ -ICG@BSA at the tumor site, and Singlet Oxygen Sensor Green (SOSG) was used to measure singlet oxygen levels in the tumor. The antitumor efficacy was assessed based on relative tumor size, bodyweight, survival curves, and hematoxylin and eosin staining.

RESULTS

The results showed that MnO₂ -ICG@BSA has a high photothermal conversion efficiency, a strong singlet oxygen-generation ability, and high photothermal stability. In addition, in vitro PTT-PDT experiments showed that MnO₂ -ICG@BSA has a significant inhibitory effect on the proliferation of B16F10 melanoma cells. Meanwhile, in vivo experiments showed that MnO₂ -ICG@BSA has a significant inhibitory effect on melanoma in mice. Preliminary toxicity studies indicated that MnO₂ -ICG@BSA exhibits low toxicity.

CONCLUSION

From the results, we can conclude that MnO₂ -ICG@BSA could be used in PTT-PDT to treat melanoma, making it a good candidate material for PTT-PDT. Lasers Surg. Med. © 2020 Wiley Periodicals LLC.

Identification of prognostic gene biomarkers for metastatic skin cancer using data mining

Skin cancer is a common malignant tumor in China and throughout the world, and the rate of recurrence is considerably high, thus endangering the quality of life and health of patients, and increasing the economic burden and pressure to the families of those afflicted. Due to the limitations of traditional drug treatments, it is difficult to achieve the desired therapeutic effect of complete removal. However, targeted gene therapy may be a novel means of treating skin cancer, as the targeted nature of treatment may improve therapeutic outcomes. However, targeted gene therapy requires physicians to select the appropriate gene, which means suitable genetic biomarkers must be identified from complex genetic data. In the present study, the least absolute shrinkage and selection operator regression analysis method was used with 10-fold cross verification to reduce the dimensions of gene data in patients with skin cancer, and subsequently, 20 gene biomarkers were screened. A prognostic model was constructed using these 20 gene biomarkers, and the validity of the model was assessed using a training set and a verification set, which showed that the model performed well. Finally, gene function analysis of these 20 gene biomarkers was determined. Relevant studies were found to show that the genetic biomarkers identified in this paper may possess value for the follow-up clinical treatment of skin cancer.

Tacrolimus and ascomycin inhibit melanoma cell growth, migration and invasion via targeting nuclear factor of activated T-cell 3

Melanoma is the most malignant form of skin cancer with high metastatic potential. Nuclear factor of activated T-cells (NFATs) are discovered as transcription factors that regulate the expression of proinflammatory cytokines and other genes during the immune response. Among five NFAT members, NFAT3 is exclusively not expressed in immune cells and its role in progression of different types of cancer remains controversial. Our previous study showed that NFAT3 was highly expressed in skin cancer compared with normal skin tissues and critical for melanoma cell survival and tumor growth. Here, we reported that knockdown of NFAT3 expression, as well as treatment with the calcineurin (CaN) inhibitors, tacrolimus (FK506) or ascomycin (FK520) inhibits melanoma cell migration and invasion, and also proliferation and colony formation. Mechanistic studies revealed that FK506 or FK520 blocked the nuclear translocation and reduced the transcriptional activity of NFAT3. These data support that the antimelanoma effect of FK506 and FK520 is partially mediated by inhibiting the oncogenic factor NFAT3, suggesting that therapeutics based on NFAT3 inhibition may be effective in clinical melanoma treatment.

Elucidation of the effect of plumbagin on the metastatic potential of B16F10 murine melanoma cells via MAPK signalling pathway

Melanoma is the most dangerous form of skin cancer with a very poor prognosis. Melanoma develops when unrepaired DNA damage causes to skin cells to multiply and form malignant tumors. The current therapy is limited by the highly ability of this disease to metastasize rapidly. Plumbagin is a naphthoquinone (5-hydroxy-2-methyl-1, 4-naphthoquinone), isolated from the roots of medicinal plant Plumbago zeylanica, and it is widely present in Lawsonia inermis L. It has been shown that plumbagin has an anti-proliferative and anti-invasive activities in various cancer cell lines; however, the anti-cancer and anti-metastatic effects of plumbagin are largely unknown against melanoma cells. In this study, we evaluated the effect of plumbagin on B16F10 murine melanoma cells . Plumbagin decreased B16F10 cell viability as well as the cell migration, adhesion, and invasion. The molecular mechanism was studied, and plumbagin downregulated genes relevant in MAPK pathway, matrix metalloproteinases (MMP's), and cell adhesion. Furthermore, plumbagin elevated the expression of apoptosis and tumors suppressor genes, and genes significant in reactive oxygen species (ROS) response. Taken together, our findings suggest that plumbagin has an anti-invasion and anti-metastasis effect on melanoma cancer cells by acting on MAPK pathway and its related genes.

Genomic, proteomic, and immunologic associations with a durable complete remission of measurable metastatic melanoma induced by a patient-specific dendritic cell vaccine

This report describes efforts to understand the immune mechanism of action that led to a complete response in a patient with progressive, refractory, metastatic melanoma after treatment with a therapeutic vaccine consisting of autologous dendritic cells (DC) loaded with autologous tumor antigens (ATA) derived from cells that were self-renewing in cell culture. Her histocompatibility type proved to be HLA B27 with extensive mutations in the HLA-A locus. Exomic analysis of proliferating tumor cells revealed more than 2800 non-synonymous mutations compared to her leukocytes. Histology of resected tumor lesions showed no evidence of an existing or suppressed immune response. In in vitro mixed cell cultures, DC loaded with ATA induced increased IL-22 expression, and a four-fold increase in CD8 + T lymphocytes. Cryopreserved blood samples obtained at week-0, 1 week before the first of three-weekly vaccine injections, and at week-4, 1 week after the third dose, were analyzed by protein array and compared for 110 different serum markers. At baseline, she had marked elevations of amyloid A, IL-12p40, IL21, IL-22, IL-10, IL-16, GROa, TNF-alpha, IL-3, and IL-2, and a lesser elevation of IL-15. One week after 3 weekly vaccinations she had a further 80% increase in amyloid A, a further 66% increase in IL-22, a 92% decrease in IL12p40, a 45% decrease in TGF-β and 26% decrease in IL-10. The data suggested that by 3 weeks after the first DCV injection, vaccine-induced changes in this particular patient were most consistent with enhanced innate and Th1 immune responses rather than Th2 or Th17.

HIF-1α/VEGF signaling-mediated epithelial-mesenchymal transition and angiogenesis is critically involved in anti-metastasis effect of luteolin in melanoma cells

Tumor metastasis is still the leading cause of melanoma mortality. Luteolin, a natural flavonoid, is found in fruits, vegetables, and medicinal herbs. The pharmacological action and mechanism of luteolin on the metastasis of melanoma remain elusive. In this study, we investigated the effect of luteolin on A375 and B16‐F10 cell viability, migration, invasion, adhesion, and tube formation of human umbilical vein endothelial cells. Epithelial–mesenchymal transition (EMT) markers and pivotal molecules in HIF‐1α/VEGF signaling expression were analysed using western blot assays or quantitative real‐time polymerase chain reaction. Results showed that luteolin inhibits cellular proliferation in A375 and B16‐F10 melanoma cells in a time‐dependent and concentration‐dependent manner. Luteolin significantly inhibited the migratory, invasive, adhesive, and tube‐forming potential of highly metastatic A375 and B16‐F10 melanoma cells or human umbilical vein endothelial cells at sub‐IC₅₀ concentrations, where no significant cytotoxicity was observed. Luteolin effectively suppressed EMT by increased E‐cadherin and decreased N‐cadherin and vimentin expression both in mRNA and protein levels. Further, luteolin exerted its anti‐metastasis activity through decreasing the p‐Akt, HIF‐1α, VEGF‐A, p‐VEGFR‐2, MMP‐2, and MMP‐9 proteins expression. Overall, our findings first time suggests that HIF‐1α/VEGF signaling‐mediated EMT and angiogenesis is critically involved in anti‐metastasis effect of luteolin as a potential therapeutic candidate for melanoma.