Immune alterations in malignant melanoma and current immunotherapy concepts

Ubiquitination of P53 by E3 ligase MKRN2 promotes melanoma cell proliferation

Melanoma is the most aggressive and lethal type of skin cancer. The aim of the present study was to illustrate the molecular mechanism of makorin ring finger protein 2 (MKRN2) control of melanoma cell proliferation. The expression level of MKRN2 was detected in human malignant melanoma cell lines by immunoblotting and reverse transcription-quantitative PCR. Short hairpin RNAs for MKRN2 were designed and transfected into melanoma cells, and the proliferation of these cells was detected by MTT and colony formation assays. The interaction of MKRN2 with P53 was detected by co-immunoprecipitation and glutathione S-transferase pulldown assays. The ubiquitination of P53 by MKRN2 was detected by in vitro ubiquitination assays. A P53-knockout cell line was generated using the CRISPR-Cas9 method. MKRN2 exhibited higher expression levels in melanoma cells, and downregulation of MKRN2 inhibited melanoma cell growth in a P53-dependent manner. MKRN2 regulated melanoma cell proliferation by interacting and ubiquitylating P53, which suggests that MKRN2 may be a potential therapeutic target for melanoma.

Exogenous IL-2 Induces FoxP3+ Th17 Cells In Vivo in Melanoma Patients

Th17 cells represent a distinct subset of CD4 effector T cells with potent pathogenic qualities, capable of directly mediating tumor cell destruction. IL-2 has frequently been shown to have a negative effect on Th17 differentiation while supporting regulatory T-cell (FoxP3CD4, TREG) growth and development in both in vitro models and in vivo animal models. We investigated the effect of in vivo IL-2 on both the Th17 and FoxP3CD4 T-cell compartments in a human model of cancer. High-dose IL-2 (HDIL-2) was administered at a dose of 720,000 IU/kg to patients with melanoma (n=7) and peripheral blood was collected at baseline and at 24, 48, 72, and 96 hours posttreatment. Peripheral blood mononuclear cells (PBMCs) were isolated and subjected to intracellular cytokine and extracellular receptor staining for flow cytometry. We report that HDIL-2 increased both frequencies and absolute numbers of Th17 cells on day 4 of treatment. The administration of HDIL-2 to patients with melanoma increased IL-6 production by peripheral immune cells, a cytokine vital in the downregulation of FoxP3 expression and expansion of the Th17-cell population. Furthermore, we demonstrated that FoxP3CD4 T cells express IL-17 in patients with melanoma undergoing HDIL-2 therapy. Taken together, our findings indicate that HDIL-2 combined with the conditions of malignancy create an immune environment supportive of Th17 differentiation and that expansion of this compartment may occur through the transdifferentiation of IL-17-secreting FoxP3CD4 T cells.

Whole Body Melanoma Transcriptome Response in Medaka

The incidence of malignant melanoma continues to increase each year with poor prognosis for survival in many relapse cases. To reverse this trend, whole body response measures are needed to discover collaborative paths to primary and secondary malignancy. Several species of fish provide excellent melanoma models because fish and human melanocytes both appear in the epidermis, and fish and human pigment cell tumors share conserved gene expression signatures. For the first time, we have examined the whole body transcriptome response to invasive melanoma as a prelude to using transcriptome profiling to screen for drugs in a medaka (Oryzias latipes) model. We generated RNA-seq data from whole body RNA isolates for controls and melanoma fish. After testing for differential expression, 396 genes had significantly different expression (adjusted p-value <0.02) in the whole body transcriptome between melanoma and control fish; 379 of these genes were matched to human orthologs with 233 having annotated human gene symbols and 14 matched genes that contain putative deleterious variants in human melanoma at varying levels of recurrence. A detailed canonical pathway evaluation for significant enrichment showed the top scoring pathway to be antigen presentation but also included the expected melanocyte development and pigmentation signaling pathway. Results revealed a profound down-regulation of genes involved in the immune response, especially the innate immune system. We hypothesize that the developing melanoma actively suppresses the immune system responses of the body in reacting to the invasive malignancy, and that this mal-adaptive response contributes to disease progression, a result that suggests our whole-body transcriptomic approach merits further use. In these findings, we also observed novel genes not yet identified in human melanoma expression studies and uncovered known and new candidate drug targets for further testing in this malignant melanoma medaka model.

Aloe-emodin exerts a potent anticancer and immunomodulatory activity on BRAF-mutated human melanoma cells

Aim of this study was to extend the knowledge on the antineoplastic effect of aloe-emodin (AE), a natural hydroxyanthraquinone compound, both in metastatic human melanoma cell lines and in primary stem-like cells (melanospheres). Treatment with AE caused reduction of cell proliferation and induction of SK-MEL-28 and A375 cells differentiation, characterized by a marked increase of transamidating activity of transglutaminase whose expression remained unmodified. In vitro antimetastatic property of AE was evaluated by adhesion and Boyden chamber invasion assays. The effect of AE on melanoma cytokines/chemokines production was determined by a multiplex assay: interestingly AE showed an immunomodulatory activity through GM-CSF and IFN-γ production. We report also that AE significantly reduced the proliferation, stemness and invasive potential of melanospheres. Moreover, AE treatment significantly enhanced dabrafenib (a BRAF inhibitor) antiproliferative activity in BRAF mutant cell lines. Our results confirm that AE possesses remarkable antineoplastic properties against melanoma cells, indicating this anthraquinone as a promising agent for differentiation therapy of cancer, or as adjuvant in chemotherapy and targeted therapy. Further, its mechanisms of action support a potential efficacy of AE treatment to counteract resistance of BRAF-mutated melanoma cells to target therapy.

Serum level of vitamin D3 in cutaneous melanoma

OBJECTIVE

To compare the level of vitamin D3 in cutaneous melanoma patients, with or without disease activity, with reference values and with patients from a general hospital.

METHODS

The serum levels of vitamin D3 were measured in cutaneous melanoma patients, aged 20 to 88 years, both genders, from January 2010 to December 2013. The samples from the general group were processed at Hospital Israelita Albert Einstein (control group). Data analysis was performed using the Statistics software.

RESULTS

A total of 100 patients were studied, 54 of them men, with mean age of 54.67 years, and 95 Caucasian. Out of these 100 patients, 17 had active disease. The average levels of vitamin D3 in the melanoma patients were lower than the level considered sufficient, but above the average of the control group. Both groups (with or without active disease) of patients showed a similar distribution of vitamin D3 deficiency.

CONCLUSION

Vitamin D3 levels in melanoma patients were higher than those of general patients and lower than the reference level. If the reference values are appropriate, a large part of the population had insufficient levels of vitamin D, including those with melanoma, or else, this standard needs to be reevaluated. No difference in vitamin D3 levels was found among melanoma patients with or without active disease. More comprehensive research is needed to assess the relation between vitamin D and melanoma.

BAP31, a promising target for the immunotherapy of malignant melanomas

PURPOSE

Malignant melanoma's (MM) incidence is rising faster than that of any other cancer in the US and the overall survival at 5 years is less than 10%. B cell associated protein 31 (BAP31) is overexpressed in most MMs and might be a promising target for immunotherapy of this disease.

EXPERIMENTAL DESIGN

Firstly, we investigated the expression profiles of human BAP31 (hBAP31) and mouse BAP31 (mBAP31) in human and mouse normal tissues, respectively. The expression level of hBAP31 in human MMs and mBAP31 in B16 melanoma cells was also analyzed. Then we constructed novel mBAP31 DNA vaccines and tested there ability to stimulate mBAP31-specific immune responses and antitumor immunity in B16 melanoma-bearing mice.

RESULTS

For the first time, we found that protein expression of hBAP31 were dramatically upregulated in human MMs when compared with human normal tissues. Predominant protein expression of mBAP31 was found in mouse B16 melanoma cells but not in mouse important organs. When mice were immunized with mBAP31 DNA vaccines, strong cellular response to mBAP31 was observed in the vaccinated mice. CTLs isolated from immunized mice could effectively kill mBAP31-positive target mouse B16 melanoma tumor cells in vitro and vaccination with mBAP31 DNA vaccines had potent anti-tumor activity in therapeutic model using B16 melanoma cells.

CONCLUSIONS

These are the first data supporting a vaccine targeting BAP31 that is capable of inducing effective immunity against BAP31-expressing MMs and will be applicable to human MMs and hBAP31 DNA vaccine warrants investigation in human clinical trials.

Favorable in vitro effects of combined IL-12 and IL-18 treatment on NK cell cytotoxicity and CD25 receptor expression in metastatic melanoma patients

Background

As IL-12 and IL-18 have important immunostimulatory role the aim of this study was to investigate their in vitro effects on functional and receptor characteristics of NK cells and their subsets in healthy controls (HC) and metastatic melanoma patients (MM).

Methods

Peripheral blood mononuclear cells (PBMC) of HC and MM were stimulated with culture medium alone, medium supplemented with IL-12 (10 ng/ml), IL-18 (100 ng/ml) and their combination. NK cell activity was determined using radioactive cytotoxicity assay, while perforin, CD107a and pSTAT-4 expression, IFN-γ production and the expression of NKG2D, DNAM-1, CD161, CD158a/b, CD25, IL-12R beta 1/2 receptors on CD3⁻CD56⁺ NK cells and their CD3⁻CD56^dim+ and CD3⁻CD56^bright+ subsets were analyzed by flow cytometry. Cytokine induced level of DAP10 in PBMC was analyzed by reverse transcription polymerase chain reaction.

Results

IL-12 alone or in combination with IL-18 significantly induced NK cell activity and CD107a degranulation marker expression in MM and HC, while IL-18 alone did not have any effect in patients. The combination of IL-12 and IL-18 significantly increased mean fluorescence intensity (MFI) of IFN-γ in all NK cell subsets in HC and only in the bright subset in MM. MM that belong to M1c group with metastasis in liver and increased LDH serum values had significantly lower increase in NK cell cytotoxicity after combined IL-12 and IL-18 treatment compared to the patients in M1a and M1b categories. These results could be explained by decreased IL-12R expression and lower increase in pSTAT-4 and perforin expression in NK cells of M1c patients after IL-12 and combined IL-12 and IL-18 treatment. IL-18 alone significantly decreased NKG2D receptor expression and level of DAP10 signaling molecule in MM, while combined IL-12 and IL-18 increased the expression of CD25 on all NK cell subsets in HC and MM. Additionally, MM that belong to M1a + M1b group had significantly higher increase in CD25 receptor expression compared to the patients in M1c group.

Conclusions

The novel data obtained in this study support the use of IL-12 and IL-18 in combination for developing new therapeutic strategies for metastatic melanoma especially for patients with better survival rate and prognosis.

Effects of BRAF mutations and BRAF inhibition on immune responses to melanoma

Malignant melanoma is associated with poor clinical prognosis; however, novel molecular and immune therapies are now improving patient outcomes. Almost 50% of melanomas harbor targetable activating mutations of BRAF that promote RAS-RAF-MEK-ERK pathway activation and melanoma proliferation. Recent evidence also indicates that melanomas bearing mutant BRAF may also have altered immune responses, suggesting additional avenues for treatment of this patient group. The small molecule inhibitors selective for mutant BRAF induce significant but short-lived clinical responses in a proportion of patients, but also lead to immune stimulatory bystander events, which then subside with the emergence of resistance to inhibition. Simultaneous BRAF and MEK inhibition, and especially combination of BRAF inhibitors with new immunotherapies such as checkpoint blockade antibodies, may further enhance immune activation, or counteract immunosuppressive signals. Preclinical evaluation and ongoing clinical trials should provide novel insights into the role of immunity in the therapy of BRAF-mutant melanoma.

Antibody therapies for melanoma: new and emerging opportunities to activate immunity (Review)

The interface between malignant melanoma and patient immunity has long been recognised and efforts to treat this most lethal form of skin cancer by activating immune responses with cytokine, vaccine and also antibody immunotherapies have demonstrated promise in limited subsets of patients. In the present study, we discuss different antibody immunotherapy approaches evaluated in the context of melanoma, each designed to act on distinct targets and to employ different mechanisms to restrict tumour growth and spread. Monoclonal antibodies recognising melanoma-associated antigens such as CSPG4/MCSP and targeting elements of tumour-associated vasculature (VEGF) have constituted long-standing translational approaches aimed at reducing melanoma growth and metastasis. Recent insights into mechanisms of immune regulation and tumour-immune cell interactions have helped to identify checkpoint molecules on immune (CTLA4, PD-1) and tumour (PD-L1) cells as promising therapeutic targets. Checkpoint blockade with antibodies to activate immune responses and perhaps to counteract melanoma-associated immunomodulatory mechanisms led to the first clinical breakthrough in the form of an anti-CTLA4 monoclonal antibody. Novel modalities to target key mechanisms of immune suppression and to redirect potent effector cell subsets against tumours are expected to improve clinical outcomes and to provide previously unexplored avenues for therapeutic interventions.

Risk of cutaneous malignant melanoma in patients with celiac disease: a population-based study

BACKGROUND

Celiac disease (CD) carries an increased risk of several malignancies, including cancers of the gastrointestinal tract and hematologic malignancies. The disease course of cutaneous malignant melanoma (CMM) is affected by the immune status of the host, and therefore may be associated with CD.

OBJECTIVE

We sought to test for an association between CD and CMM in a population-based setting.

METHODS

We queried all (n = 28) pathology departments in Sweden and identified patients with intestinal histology consistent with CD. Each patient was matched to up to 5 control subjects by age, gender, calendar period, and region. Using Cox proportional hazards, we tested for an association between CD and the subsequent diagnosis of CMM.

RESULTS

Among patients with CD (n = 29,028), 78 subsequently developed CMM (0.3%). Compared with control subjects there was no significant association between CD and CMM (hazard ratio 0.94, 95% confidence interval 0.73-1.20). This null association was similar for men (hazard ratio 0.99, 95% confidence interval 0.68-1.44) and women (hazard ratio 0.89, 95% confidence interval 0.64-1.24), and in all age strata.

LIMITATIONS

Lack of data regarding undiagnosed CD is a limitation.

CONCLUSION

In this population-based study we found no association between CD and the subsequent diagnosis of CMM. Prior studies showing a positive association between these 2 entities may have been a result of referral bias.

Updates on immunotherapy in non-small cell lung cancer

Immunotherapy has made significant progress in patients with non-small cell lung cancer (NSCLC) in the last years. Early tumor vaccine studies showed trends toward better clinical outcomes, and larger trial results are currently being awaited. Immune checkpoint inhibitors are promising therapeutic agents in advanced NSCLC. While ipilimumab, a cytotoxic T-lymphocyte antigen 4 inhibitor, has clearly improved outcomes in metastatic malignant melanoma, its safety and efficacy in NSCLC are not yet known. Programmed death-1 (PD-1) and PD-1 ligand inhibitors such as nivolumab, MK3475 and MPDL3280 have demonstrated clinical efficacy in patients with advanced/metastatic NSCLC in early clinical trials. Their validation in larger Phase III trials is anxiously being awaited. Furthermore, exploring efficacy of these molecules in patients with early stages of lung cancer is also necessary.