Recent advances in cutaneous melanoma: towards a molecular model and targeted treatment

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.

LncRNA MEG3 promotes melanoma growth, metastasis and formation through modulating miR-21/E-cadherin axis

Background

Melanoma is the most aggressive type of skin cancer with high mortality rate and poor prognosis. lncRNA MEG3, a tumor suppressor, is closely related to the development of various cancers. However, the role of lncRNA MEG3 in melanoma has seldom been studied.

Methods

RT-PCR was used to examine the expressions of lncRNA MEG3 and E-cadherin in melanoma patients and cell lines. Then, the biological functions of lncRNA MEG3 and E-cadherin were demonstrated by transfecting lncRNA MEG3-siRNA, lncRNA MEG3-overexpression, E-cadherin-siRNA and E-cadherin-overexpression plasmids in melanoma cell lines. Moreover, CCK8 assay and colony formation assay were utilized to assess the cell proliferation; Transwell assay was performed to evaluate the cell invasive ability; and tumor xenografts in nude mice were applied to test the tumor generation. Additionally, the target interactions among lncRNA MEG3, miR-21 and E-cadherin were determined by dual luciferase reporter assay. Finally, RT-PCR and WB were further conducted to verify the regulatory roles among lncRNA MEG3, miR-21 and E-cadherin.

Results

The clinical data showed that lncRNA MEG3 and E-cadherin expressions were both declined in carcinoma tissues as compared with their para-carcinoma tissues. Moreover, lncRNA MEG3 and E-cadherin expressions in B16 cells were also higher than those in A375 and A2058 cells. Subsequently, based on the differently expressed lncRNA MEG3 and E-cadherin in these human melanoma cell lines, we chose B16, A375 and A2058 cells for the following experiments. The results demonstrated that lncRNA MEG3 could suppress the tumor growth, tumor metastasis and formation; and meanwhile E-cadherin had the same effects on tumor growth, tumor metastasis and formation. Furthermore, the analysis of Kaplan–Meier curves also confirmed that there was a positive correlation between lncRNA MEG3 and E-cadherin. Ultimately, dual luciferase assays were further used to verify that lncRNA MEG3 could directly target miR-21 which could directly target E-cadherin in turn. Additionally, the data of RT-PCR and WB revealed that knockdown of lncRNA MEG3 in B16 cells inhibited miR-21 expression and promoted E-cadherin expression, but overexpression of lncRNA MEG3 in A375 and A2058 cells presented completely opposite results.

Conclusion

Our findings indicated that lncRNA MEG3 might inhibit the tumor growth, tumor metastasis and formation of melanoma by modulating miR-21/E-cadherin axis.

Monitoring BRAF and NRAS mutations with cell-free circulating tumor DNA from metastatic melanoma patients

The mutation status of the BRAF and NRAS genes in tumor tissue is used to select patients with metastatic melanoma for targeted therapy. Cell-free circulating DNA (cfDNA) represents an accessible, non-invasive surrogate sample that could provide a snapshot of the BRAF and NRAS genotype in these patients. We investigated the feasibility of the Idylla™ assay for detection of BRAF and NRAS mutations in cfDNA of 19 patients with metastatic melanoma at baseline and during the course of treatment. The cfDNA genotype obtained with Idylla was compared to the results obtained with matched-tumor tissue and to clinical outcome. At baseline, 47% of patients harbored a BRAFV600 mutation in their cfDNA. Two months after targeted treatment the BRAFV600 mutant cfDNA was undetectable in all patients and 3 were disease-free. Moreover, 15% of patients harbored a NRAS mutation that was detected with plasma before treatment. The sensitivity and specificity were 80% and 89% for the BRAF status, and 79% and 100% for the NRAS status in pretreatment cfDNA compared to results obtained with a tissue test. Due to the small size of the population, no significant correlation was observed between the presence of BRAF or NRAS mutations in cfDNA and the metastatic tumor load or overall survival. In conclusion, this study demonstrated that evaluation with the Idylla system of the BRAF and NRAS mutation status in cfDNA may be a surrogate for determination of the BRAF and NRAS status in tumor tissue.

Nanomedicine as a potent strategy in melanoma tumor microenvironment

Melanoma originated from melanocytes is the most aggressive type of skin cancer. Despite considerable progresses in clinical treatment with the discovery of BRAF or MEK inhibitors and monoclonal antibodies, the durability of response to treatment is often limited to the development of acquired resistance and systemic toxicity. The limited success of conventional treatment highlights the importance of understanding the role of melanoma tumor microenvironment in tumor developement and drug resistance. Nanoparticles represent a promising strategy for the development of new cancer treatments able to improve the bioavailability of drugs and increase their penetration by targeting specifically tumors cells and/or tumor environment. In this review, we will discuss the main influence of tumor microenvironment in melanoma growth and treatment outcome. Furthermore, third generation loaded nanotechnologies represent an exciting tool for detection, treatment, and escape from possible mechanism of resistance mediated by tumor microenvironment, and will be highlighted in this review.

Diffuse melanosis cutis in the setting of BRAF(V600E) metastatic melanoma

CASE REPORT

A 79-year-old Caucasian male presented with a 1-week history of diffuse progressive blue-gray discoloration of the skin subsequently found to due to diffuse melanosis cutis (DMC) in the setting of metastatic melanoma. Mutation testing demonstrated BRAF(V600E) mutation status, an unexpected finding given his age. He died two weeks after presentation.

DISCUSSION

As our understanding of the molecular subtypes of melanoma increases, in the future it may be possible to predict which melanoma patients have a predilection to developing DMC. Mutation testing of DMC patients should be considered as BRAF inhibitors, and other novel targeted therapies may improve the bleak prognosis associated with this unusual presentation of metastatic melanoma.

Radiation therapy for advanced and metastatic melanoma

Radiation therapy (RT) is an important modality in cancer treatment. However, the general perception is that melanoma is radio-resistant. High quality clinical trials are helping to establish the place of RT in select scenarios of advanced disease at primary, regional, and distant sites. New RT techniques need to be integrated with effective new systemic therapies within a multidisciplinary environment to ensure optimum patient outcomes. It is important that radiation oncologists embrace this opportunity.

Risk of subsequent primary tumor development in melanoma patients

Incidence of subsequent malignant tumor development in 740 patients with primary cutaneous melanoma verified between 2006 and 2010 at the Semmelweis University was studied retrospectively and was compared to data of sex and age matched Hungarian population. The follow-up period was 1499 person-years for the whole group from the diagnosis of index melanoma with an average of 2 years. Standardized incidence rate (SIR) was established as the ratio of observed and expected values. The risk of all subsequent malignancies was 15- and 10-fold higher in males (SIR: 15.42) and in females (SIR: 10.55) with melanoma, than in the general population. The increased cancer risk resulted mainly from the significantly higher skin tumor development: SIR values were 160.39 and 92.64 for additional invasive melanoma and 342.28 and 77.04 for subsequent in situ melanoma in males and females, respectively. Non-melanoma skin cancers also notably contributed to the higher risk, the SIR was elevated in both genders to the same extent (males: 17.12, females: 17.55). The risk was also significantly higher for extracutaneous tumor development like chronic lymphocytic leukemia, colon and kidney cancer (both genders), non-Hodgkin's lymphoma, cervical cancer (females), and bladder carcinoma (males). These data underline the importance of patient education and the necessity of frequent medical follow up, including a close-up dermatological screening of melanoma survivors for further malignancies.