miRNAs and Melanoma: How Are They Connected?

Prognostic Significance of miRNA Subtypes in Melanoma: A Survival Analysis and Correlation with Treatment Response Across Patient Stages

BACKGROUND AND OBJECTIVES

Melanoma remains a leading cause of skin cancer mortality despite advancements in targeted therapies and immunotherapies. MicroRNAs (miRNAs) have emerged as potential biomarkers for cancer prognosis and treatment response. This study aims to analyze survival outcomes according to various miRNA subtypes, assess the association between specific miRNAs and treatment response, and include patient staging to evaluate their prognostic significance.

METHODS

A retrospective cohort study was conducted on 90 patients from the Pius Brinzeu County Emergency Clinical Hospital, Timisoara, between 2019 and 2022. The cohort included 45 patients with advanced-stage melanoma and 45 with benign nevi. miRNA expression levels were quantified using the miRNeasy Kit and the Human Cancer PathwayFinder miScript miRNA PCR Array. Survival analysis was performed using the Kaplan-Meier method, and Cox proportional hazards models were used to assess the impact of miRNA expression on survival. Logistic regression analyzed the association between miRNA markers and treatment response, adjusting for patient staging.

RESULTS

Elevated levels of hsa-miR-200a-3p and hsa-miR-335-5p were significantly associated with poorer overall survival (p < 0.01), particularly in stage III and IV patients. Conversely, higher expression of hsa-miR-451a correlated with improved survival rates (p = 0.02). Patients with increased hsa-miR-29b-3p expression showed a better response to immunotherapy (OR = 2.35, 95% CI: 1.15-4.79). Multivariate analysis confirmed that miRNA expression levels and patient staging were independent predictors of survival and treatment response.

CONCLUSIONS

Specific miRNA subtypes are significant prognostic markers in melanoma, influencing survival outcomes and treatment responses across different patient stages. Incorporating miRNA profiling into clinical practice could enhance personalized treatment strategies and improve patient prognoses.

Role of miRNAs in Melanoma Metastasis

Tumour metastasis is a multistep process. Melanoma is a highly aggressive cancer and metastasis accounts for the majority of patient deaths. microRNAs (miRNAs) are non-coding RNAs that affect the expression of their target genes. When aberrantly expressed they contribute to the development of melanoma. While miRNAs can act locally in the cell where they are synthesized, they can also influence the phenotype of neighboring melanoma cells or execute their function in the direct tumour microenvironment by modulating ECM (extracellular matrix) and the activity of fibroblasts, endothelial cells, and immune cells. miRNAs are involved in all stages of melanoma metastasis, including intravasation into the lumina of vessels, survival during circulation in cardiovascular or lymphatic systems, extravasation, and formation of the pre-metastatic niche in distant organs. miRNAs contribute to metabolic alterations that provide a selective advantage during melanoma progression. They play an important role in the development of drug resistance, including resistance to targeted therapies and immunotherapies. Distinct profiles of miRNA expression are detected at each step of melanoma development. Since miRNAs can be detected in liquid biopsies, they are considered biomarkers of early disease stages or response to treatment. This review summarizes recent findings regarding the role of miRNAs in melanoma metastasis.

MicroRNA-373 promotes cell migration via targeting salt-inducible kinase 1 expression in melanoma

It is well established that altered expression of microRNAs (miRs) is critical in numerous human cancer types. Nevertheless, the molecular mechanisms of many miRs are yet to be elucidated. In the present study, reverse transcription-quantitative polymerase chain reaction and western blot analyses, and cell migration assays were performed to verify dysregulation of miR-373 in melanoma and its biological function. The transcriptional level of miR-373 was identified to be upregulated in melanoma tissues and cell lines compared with nevus and normal melanocytes. miR-373 was identified to function as an oncomiR, promoting melanoma cell migration. Notably, miR-373 was observed to suppress its downstream gene salt-inducible kinase 1 (SIK1) through directly binding the 3'-untranslated region of SIK1 expression. Furthermore, reduced SIK1 expression was identified to be responsible for the oncogenic effect of miR-373. In conclusion, the present study indicates that miR-373 functions as an oncomiR to promote melanoma progression through targeting SIK1 expression. This may provide a new therapeutic approach for melanoma.

MiR-21: an environmental driver of malignant melanoma?

Since the mid-1950’s, melanoma incidence has been rising steadily in industrialized Caucasian populations, thereby pointing to the pivotal involvement of environmental factors in melanomagenesis. Recent evidence underlines the crucial role of microRNA (miR) signaling in cancer initiation and progression. Increased miR-21 expression has been observed during the transition from a benign melanocytic lesion to malignant melanoma, exhibiting highest expression of miR-21. Notably, common BRAF and NRAS mutations in cutaneous melanoma are associated with increased miR-21 expression. MiR-21 is an oncomiR that affects critical target genes of malignant melanoma, resulting in sustained proliferation (PTEN, PI3K, Sprouty, PDCD4, FOXO1, TIPE2, p53, cyclin D1), evasion from apoptosis (FOXO1, FBXO11, APAF1, TIMP3, TIPE2), genetic instability (MSH2, FBXO11, hTERT), increased oxidative stress (FOXO1), angiogenesis (PTEN, HIF1α, TIMP3), invasion and metastasis (APAF1, PTEN, PDCD4, TIMP3). The purpose of this review is to provide translational evidence for major environmental and individual factors that increase the risk of melanoma, such as UV irradiation, chemical noxes, air pollution, smoking, chronic inflammation, Western nutrition, obesity, sedentary lifestyle and higher age, which are associated with increased miR-21 signaling. Exosomal miR-21 induced by extrinsic and intrinsic stimuli may be superimposed on mutation-induced miR-21 pathways of melanoma cells. Thus, oncogenic miR-21 signaling may be the converging point of intrinsic and extrinsic stimuli driving melanomagenesis. Future strategies of melanoma treatment and prevention should thus aim at reducing the burden of miR-21 signal transduction.

HOX Gene Aberrant Expression in Skin Melanoma: A Review

The homeobox family and its subset of HOX gene products represent a family of transcription factors directing DNA-protein and protein-protein interactions. In the embryo, they are central regulators in cell differentiation during morphogenesis. A series of genes of the four HOX gene clusters A, B, C, and D were reported to show aberrant expressions in oncogenesis, particularly in cutaneous malignant melanoma (CMM). They are involved in cell proliferation and progression in the CMM metastatic path. We present relevant peer-reviewed literature findings about the aberrant expression of HOX genes in CMM. The number of CMM cell nuclei exhibiting aberrant HOX protein expression appears correlated with tumour progression.