PD-L1 expression is regulated by microphthalmia-associated transcription factor (MITF) in nodular melanoma.

Malignant melanoma (MM) is known to avoid the host's immune response. Studies on in vitro melanoma cell lines link the microphthalmia-associated transcription factor (MITF) with the regulation of the PD-L1 expression. It seems that MITF affects the activation of the gene responsible for PD-L1 protein expression. Several proteins, including Bcl-2 and Cyclin D1, play major roles in malignant melanoma cell cycle regulation and survival. Our study aims to assess the relationship between MITF, Bcl-2, and cyclin D1 protein expression and the expression of the PD-L1 molecule. Additionally, we examined the association of BRAF mutation, MITF, and CCND1 gene amplification with PD-L1 protein expression. We performed immunohistochemical staining on fifty-two tumour samples from patients diagnosed with nodular melanoma (NM). BRAF V600 mutation, MITF, and CCND1 gene amplification analyses were analyzed by the Sanger sequencing and QRT-PCR methods, respectively. Statistical analyses confirmed the significant inverse correlation between cyclin D1 and PD-L1 expression (p = 0.001) and correlation between PD-L1 and MITF protein expression (p = 0.023). We found a statistically significant inverse correlation between the present MITF gene amplification and PD-L1 (p = 0.007) and MITF protein expression (p = 3.4 ×10-6), respectively. Our study, performed on clinical NM materials, supports the in vitro study findings providing a rationale for the potential MITF-dependent regulation of PD-L1 expression in malignant melanoma.

Matrix metalloproteinases MMP-1, MMP-2, and MMP-13 are overexpressed in primary nodular melanoma.

BACKGROUND: The spread and invasion of malignant melanoma cells involve degradation and reorganization of the extracellular matrix by the activation of several matrix metalloproteinases (MMPs). This study analyzed the expression of MMP-1, MMP-2, and MMP-13 proteins in primary nodular melanoma (NM) and dysplastic nevi (DN) as a significant risk factor for melanoma development. The secondary goal was to analyze the correlation of MMPs protein expression in NM with tumor invasion, BRAF V600 mutation status, and overall survival. METHODS: Immunohistochemistry for MMP-1, MMP-2, and MMP-13 was performed on nodular melanoma (n = 52) and dysplastic nevi (n = 28) on tissue microarray (TMA). BRAF V600 mutation analysis on NM samples was performed by the Sanger sequencing method. RESULTS: A high level of MMPs expression in NM samples (>30%) compared with DN (<8%) was statistically significant (P < 0.001). BRAF V600 mutations were detected in 15 of 39 (38.5%) NM samples. This study revealed an interesting finding that MMP-1 and MMP-13 protein expression in the BRAF V600 mutated melanomas were significantly lower than in the BRAF V600 wild type (P < 0.05). CONCLUSION: Cox analysis revealed that Clark categories, Breslow thickness, and MMP-1 high protein expression are predictive factors for shorter overall survival (P < 0.05).

Recurrent amelanotic melanoma of nasal cavity: Biological variability and unpredictable behavior of mucosal melanoma. A case report.

The aim of this report is to present a case of a patient with a recurrent nasal cavity amelanotic melanoma (AM), with emphasis on diagnosis and therapy options of this clinical entity. A 65-year-old female patient presented with pain in the right cheek region and nasal obstruction. In 2013, she was diagnosed with mucosal melanoma (MM) of the left nasal cavity. After endoscopic surgery and radiotherapy, the patient was followed by the oncology team. Five years after the initial diagnosis, rhinoscopy showed a tumorous formation in the right nasal cavity. The tumor mass was without black discoloration and was the same color as the surrounding nasal mucosa. Microscopic examination after biopsy of the tumor confirmed amelanotic MM. The patient underwent an additional endoscopic surgery. A complete standard diagnostic workup for MM found metastases in head and neck lymph nodes, on both sides. MMs of head and neck are uncommon malignancies. Unique biology of MM cells causes a high rate of recurrences. This report presents an example of recurrent AM of the nasal cavity, in treatment with checkpoint inhibitor (pembrolizumab), which could provide a good therapy option for patients with MM.