The Interplay between Tumour Microenvironment Components in Malignant Melanoma

Malignant melanoma has shown an increasing incidence during the last two decades, exhibiting a large spectrum of locations and clinicopathological characteristics. Although current histopathological, biochemical, immunohistochemical, and molecular methods provide a deep insight into its biological behaviour and outcome, melanoma is still an unpredictable disease, with poor outcome. This review of the literature is aimed at updating the knowledge regarding melanoma’s clinicopathological and molecular hallmarks, including its heterogeneity and plasticity, involving cancer stem cells population. A special focus is given on the interplay between different cellular components and their secretion products in melanoma, considering its contribution to tumour progression, invasion, metastasis, recurrences, and resistance to classical therapy. Furthermore, the influences of the specific tumour microenvironment or “inflammasome”, its association with adipose tissue products, including the release of “extracellular vesicles”, and distinct microbiota are currently studied, considering their influences on diagnosis and prognosis. An insight into melanoma’s particular features may reveal new molecular pathways which may be exploited in order to develop innovative therapeutic approaches or tailored therapy.

Antitumor effect of cell therapy with mesenchymal stem cells on murine melanoma B16-F10

In this study, the antitumor and immunomodulatory effects of mesenchymal stem cells (MSC) obtained from bone marrow in the treatment of dorsal melanoma B16-F10. The MSC cells were obtained from the bone marrow of isogenic C57BL/6J mice, characterized and inoculated by two routes, intratumor (it) and intravenous (iv). The hematological profile, expression markers and receptors, phases of the cell cycle and mitochondrial electrical potential were evaluated by flow cytometry. The dorsal tumor mass showed a significant reduction after treatment by the two routes of administration with a significant effect by the intravenous route. MSC showed immunomodulatory potential and did not induce an increase in the markers involved in tumor control and progression. The number of cells in the sub-G1 phase increased significantly after treatments compared to the control group. The percentage of cells in phases G0/G1, S and G2/M decreased, with only the group (it) showing a significant reduction. The intratumor group showed a significant decrease in the G2/M phase. Treatment with MSC provided a significant decrease in the percentage of metabolically active tumor cells, demonstrating its intrinsic effect in the control of cell proliferation. Regarding the mechanism of cell death, MSCs modulated the expression of proteins involved in the regulation of the cell cycle, angiogenesis receptors and pro-apoptotic proteins by intrinsic and extrinsic routes. Therefore, the use of undifferentiated MSC, administered intratumor and intravenous is possibly a promising treatment for melanoma.

Isocitrate dehydrogenase 1 mutations in melanoma frequently co-occur with NRAS mutations

AIMS

Isocitrate dehydrogenase 1 (IDH1) is a metabolic enzyme that converts isocitrate to α-ketoglutarate. IDH1 mutations are associated with the accumulation of the oncometabolite D-2-hydroxyglutarate, which acts as an epigenetic modifier, and the development of multiple malignancies.

METHODS AND RESULTS

From May 2013 to June 2017, 252 melanoma samples from 214 patients with advanced or distant metastatic disease were tested for somatic mutations with the 50-gene AmpliSeq version 2 Cancer Hotspot Panel. Two hundred and twenty-six samples were sequenced successfully from 206 patients with 26 samples being characterised as quantity not sufficient. Melanomas from 10 separate patients (4.9%) were positive for IDH1 R132C (nine) or R132S (one). In six cases, the tumours also had a co-existing NRAS mutation (p.Q61R, Q61L and Q61K in two patients each) (P = 0.0044), whereas three patients had BRAF non-V600E mutations (V600K, V600G and V600R). Two cases had a TP53 variant, two cases an ATM variant, one a CDKN2A variant and one had an APC variant. The patients' ages ranged from 45 to 82 years (mean = 65.3, median = 65 years) and three of 10 patients were female (M:F ratio = 2:3). Three patients were stage 3 and seven were stage 4. Two are deceased, five are alive with stable disease (four on pembrolizumab) and three have no evidence of disease.

CONCLUSION

IDH mutations may define a unique subset of melanoma patients who are eligible for IDH1 targeted therapies or combined therapies, such as MEK inhibitors when there is co-existing NRAS mutations, or immunotherapy.

Metastases risk in thin cutaneous melanoma: prognostic value of clinical-pathologic characteristics and mutation profile

Background

A high percentage of patients with thin melanoma (TM), defined as lesions with Breslow thickness ≤1 mm, presents excellent long-term survival, however, some patients develop metastases. Existing prognostic factors cannot reliably differentiate TM patients at risk for metastases.

Objective

We aimed at characterizing the clinical-pathologic and mutation profile of metastatic and not-metastatic TM in order to distinguish lesions at risk of metastases.

Methods

Clinical-pathologic characteristics were recorded for the TM cases analyzed. We used a Next Generation Sequencing (NGS) multi-gene panel to characterize TM for multiple somatic mutations.

Results

A statistically significant association emerged between the presence of metastases and Breslow thickness ≥0.6 mm (p=0.003). None of TM with lymph-node involvement had Breslow thickness <0.6 mm. Somatic mutations were identified in 19 of 21 TM analyzed (90.5%). No mutations were observed in two not-metastatic cases with the lowest Breslow thickness (≤0.4 mm), whereas mutations in more than one gene were detected in one metastatic case with the highest Breslow thickness (1.00 mm).

Conclusion

Our study indicates Breslow thickness ≥0.6 mm as a valid prognostic factor to distinguish TM at risk for metastases.

Clinicopathological characteristics and mutation profiling in primary cutaneous melanoma

BACKGROUND

The incidence of mutations in malignant melanoma varies remarkably according to the subtype of melanoma, and this in itself is affected by racial and geographical factors. Studies screening melanoma case series for different types of mutations are relatively rare.

METHOD

The authors analyzed the frequency of various somatic point mutations of 10 genes in 106 primary cutaneous melanoma cases. The mutations (BRAF, NRAS, KIT, CDKN2A, KRAS, HRAS, PIK3CA, STK11, GNAQ, CTNNB1) were evaluated with real-time PCR-based PCR-Array through allele-specific amplification, and the results were correlated with various clinicopathological characteristics.

RESULTS

Mutations were found in 64.2% of the melanomas overall. BRAF (42.5%), NRAS (15.1%), and CDKN2A (13.2%) were the 3 most common mutations. BRAF and NRAS mutations were more frequent in nodular and superficial spreading melanomas (P < 0.001). Associations with BRAF mutation were as follows: male gender [odds ratio (OR) = 2.4], younger age (OR = 2.7), superficial spreading (OR = 15.6) and nodular melanoma (OR = 9.5), trunk localization (OR = 6.3), and intermittent sun exposure (OR = 4.6). A considerable percentage of V600K (44.4%) mutations were found among the BRAF mutations, whereas KIT mutations (3.8%) were less frequent. Multiple mutations were detected in 13.2% of the melanomas. The most common co-occurrences were in the BRAF, NRAS, and CDKN2A genes.

CONCLUSIONS

The authors analyzed 10 somatic mutations in the main subtypes of primary cutaneous melanomas from the western region of Turkey. Mutations were found in 64.2% of the melanomas overall. The most common mutations were in the BRAF and NRAS genes. In addition to other less common mutations, a notable number of multiple mutations were encountered. The multiplicity and concurrence of mutations in this study may provide further study areas for personalized targeted therapy.

Update on Molecular Pathology of Cutaneous Melanocytic Lesions: What is New in Diagnosis and Molecular Testing for Treatment?

In this article, we give an update on recent findings regarding molecular pathology in cutaneous melanocytic tumors. The focus lies on use of genetics in the diagnosis of distinct subtypes of spitzoid tumors that are often characterized by specific phenotypic–genotypic alterations that can frequently be recognized by adequate histological examination. Typical illustrating cases are given in order to increase recognition of these lesions in daily dermatopathology practice. New molecular findings in the pathogenesis of congenital melanocytic tumors and neurocutaneous melanosis are reviewed. In addition, use of mutation analysis in the differential diagnosis of melanoma metastasis is discussed. Finally, application of mutation analysis in targeted therapy in advanced melanoma with advantages of new techniques such as next generation sequencing is described.