Advances in melanoma research have unveiled critical insights into its genetic and molecular landscape, leading to significant therapeutic innovations. This review explores the intricate interplay between genetic alterations, such as mutations in BRAF, NRAS, and KIT, and melanoma pathogenesis. The MAPK and PI3K/Akt/mTOR signaling pathways are highlighted for their roles in tumor growth and resistance mechanisms. Additionally, this review delves into the impact of epigenetic modifications, including DNA methylation and histone changes, on melanoma progression. The tumor microenvironment, characterized by immune cells, stromal cells, and soluble factors, plays a pivotal role in modulating tumor behavior and treatment responses. Emerging technologies like single-cell sequencing, CRISPR-Cas9, and AI-driven diagnostics are transforming melanoma research, offering precise and personalized approaches to treatment. Immunotherapy, particularly immune checkpoint inhibitors and personalized mRNA vaccines, has revolutionized melanoma therapy by enhancing the body’s immune response. Despite these advances, resistance mechanisms remain a challenge, underscoring the need for combined therapies and ongoing research to achieve durable therapeutic responses. This comprehensive overview aims to highlight the current state of melanoma research and the transformative impacts of these advancements on clinical practice.

Background/Objectives: Melanoma is an aggressive skin cancer influenced by genetic and immunological factors. The PDCD1 gene encodes PD-1, a receptor involved in immune evasion and therapeutic response. This study aimed to evaluate the association of PDCD1 variants (rs2227982, rs36084323, rs7421861) and its relative gene expression with melanoma in a Mexican population. Methods: An analytical cross-sectional study was conducted with 262 samples: 131 from melanoma patients (newly diagnosed and treatment-naïve) and 131 from cancer-free controls. Genotyping was performed using real-time PCR. PDCD1 expression was assessed by qPCR, normalized with GAPDH, using the 2^−ΔΔCt method and the Pfaffl model. Statistical comparisons included allele/genotype frequencies, expression levels, and clinicopathological associations. Results: No significant association was found between the studied PDCD1 variants and melanoma susceptibility. However, PDCD1 was significantly overexpressed in melanoma samples (2.42-fold increase; p < 0.01), consistent across both quantification methods. Significant associations were also observed between histopathological subtype and Breslow thickness, and between subtype and anatomical site (p < 0.01). Conclusions: Although PDCD1 variants showed no association with melanoma risk, the gene’s overexpression highlights its potential relevance in melanoma immunobiology. These findings contribute to the molecular characterization of melanoma in the Mexican population and support future research on PDCD1 as an immunological biomarker.

Objective: To analyze the association between the IRF5 gene variants rs3807135, rs3757385, and rs3778754 and mRNA expression levels in patients from western Mexico diagnosed with melanoma. Methods: An analytical cross-sectional study was conducted including 374 individuals (153 patients with newly diagnosed melanoma and no previous treatment, and 221 controls). The melanoma group was matched to the reference group. Genotyping of the rs3807135 (T>C), rs3757385 (T>G), and rs3778754 (C>G) variants was performed using the allelic discrimination method with TaqMan^® probes. Relative mRNA expression was quantified by qPCR using the 2^–ΔΔCT method, comparing IRF5 expression levels with those of the housekeeping gene GAPDH. Statistical analyses were performed in R, and allelic and genotypic frequencies were compared between patients and controls using the Chi-square test. Results: No statistically significant associations were identified between IRF5 SNVs rs3807135, rs3757385, and rs3778754 and melanoma risk. The haplotypic pattern comprised TTC, CGG, and CGC, with CGG showing a non-significant protective tendency. The mean relative expression of IRF5 was lower in melanoma patients compared with controls (≈0.39 vs. 1.0; Δ = 0.61), although this difference did not reach statistical significance (U = 1725; p = 0.841). These findings suggest a modest modulatory effect of IRF5 at the haplotypic level, likely driven by combined variant effects. Conclusions: In conclusion, the present study did not identify statistically significant associations between the IRF5 single-nucleotide variants rs3807135, rs3757385, and rs3778754 and melanoma risk in the analyzed population from western Mexico. Likewise, no significant differences in allele or genotype distributions were observed between melanoma patients and control individuals. These findings suggest that the evaluated IRF5 genetic variants do not constitute major susceptibility factors for melanoma in this cohort.

Background: Interferon regulatory factor 5 (IRF5) is a master transcription factorcontrolling innate immune responses, type I interferon signaling, proinflammatorycytokine production, and apoptosis. IRF5 dysregulation is implicated intumorigenesis and cancer progression; however, its upstream post-transcriptionalcontrol mechanisms have not been fully characterized. MicroRNAs (miRNAs) haveemerged as key post-transcriptional regulators capable of fine-tuning IRF5expression, and understanding their potential impact on tumor microenvironment(TME) remodeling is important.Objective: To summarize current scientific evidence regarding miRNA-mediatedpost-transcriptional regulation of IRF5 and to estimate its impact on tumor initiation,progression, and immune surveillance, focusing on diagnostic, prognostic, andtherapeutic implications.Methods and mechanisms: A systematic literature review was conducted toidentify miRNAs that directly target the 3'UTR region of IRF5 mRNA across variousphysiological, pathological, and experimental models. The functional consequencesof these regulatory interactions were analyzed in relation to cancer hallmarks.Results: Multiple miRNAs—including miR-146b, miR-302a, miR-22-3p, miR-125a-5p, miR-129-1-3p, miR-193b-5p, and miR-133a-3p—directly repress IRF5expression. IRF5 repression by these miRNAs primarily promotes macrophagepolarization toward an immunosuppressive state (shifting from an M1 to an M2-likephenotype), attenuates type I/II interferon signaling, and reduces proinflammatorycytokine production. Furthermore, the upregulation of specific miRNAs—driven byoncogenes (e.g., MYC-mediated) or induced by hypoxia—acts on IRF5 to facilitatecell cycle progression, evade apoptosis, and promote proliferation. Notably, thetransfer of miRNAs (such as miR-125a-5p) via exosomes highlights an intercellularcommunication axis involved in remodeling the tumor microenvironment (TME).Conclusion: The miRNA-IRF5 axis represents a crucial regulatory node linkingmetabolic stress and the microenvironment. The context-dependent modulation ofthis axis underscores the importance of studying it, as it could serve as a potentialdiagnostic biomarker and a target for TME reprogramming.