Melanoma progression is a multistep evolution from a common melanocytic nevus through a radial superficial growth phase, the invasive vertical growth phase finally leading to metastatic dissemination into distant organs. Melanoma aggressiveness largely depends on the propensity to metastasize, which means the capacity to escape from the physiological microenvironment since tissue damage due to primary melanoma lesions is generally modest. Physiologically, epidermal melanocytes are attached to the basement membrane, and their adhesion/migration is under the control of surrounding keratinocytes. Thus, the epidermal compartment represents the first microenvironment responsible for melanoma spread. This complex process involves cell–cell contact and a broad range of secreted bioactive molecules. Invasion, or at the beginning of the microinvasion, implies the breakdown of the dermo-epidermal basement membrane followed by the migration of neoplastic melanocytic cells in the superficial papillary dermis. Correspondingly, several experimental evidences documented the structural and functional rearrangement of the entire tissue surrounding neoplasm that in some way reflects the atypia of tumor cells. Lastly, the microenvironment must support the proliferation and survival of melanocytes outside the normal epidermal–melanin units. This task presumably is mostly delegated to fibroblasts and ultimately to the self-autonomous capacity of melanoma cells. This review will discuss remodeling that occurs in the epidermis during melanoma formation as well as skin changes that occur independently of melanocytic hyperproliferation having possible pro-tumoral features.

Background: Vitiligo is featured by the manifestation of white maculae and primarily results from inflammatory/immune-selective aggression to melanocytes. The trigger mechanism leading to the activation of resident immune cells in the skin still lacks a molecular description. There is growing evidence linking altered mitochondrial metabolism to vitiligo, suggesting that an underlying metabolic defect may enable a direct activation of the immune system. Recent evidence demonstrated the association of vitiligo with disorders related to systemic metabolism, including insulin resistance (IR) and lipid disarrangements. However, IR, defined as a cellular defect in the insulin-mediated control of glucose metabolism, and its possible role in vitiligo pathogenesis has not been proven yet. Methods: In this study, we compared the Ins/IGF-1 intracellular signaling of dermal and epidermal cells isolated from non-lesional vitiligo skin to that belonging to cells obtained from healthy donors. Results: We demonstrated that due to the intensified glucose uptake, S6, and insulin receptor substrate 1 (IRS1) chronic phosphorylation, their inducibilities were downsized, a condition that coincides with the definition of insulin resistance at the cellular level. Correspondingly, the mitogenic and metabolic activities normally provoked by Ins/IGF-1 exposure resulted in significantly compromised vitiligo cells (p ≤ 0.05). Besides all the vitiligo-derived skin cells manifesting an energetic disequilibrium consisting of a low ATP, catabolic processes activation, and chronic oxidative stress, the functional consequences of this state appear amplified in the keratinocyte lineage. Conclusion: The presented data argue for insulin and IGF-1 resistance collocating dysfunctional glucose metabolism in the mechanisms of vitiligo pathogenesis. In vitiligo keratinocytes, the intrinsic impairment of intracellular metabolic activities, particularly when associated with stimulation with Ins/IGF-1, converges into an aberrant pro-inflammatory phenotype that may initiate immune cell recruitment.

The Tumour Microenvironment (TME) is pivotal for melanoma progression and contributes to therapy resistance. While dermal cell involvement is well established, the role of epidermal cells remains less defined. To explore the contribution of Normal Human Keratinocytes (NHKs) to melanoma biology, we investigated the modification of gene and protein expression of NHKs exposed to melanoma-conditioned medium or maintained in a co-culture system. The analysis focused on pathways related to proliferation, inflammation, Extracellular Matrix (ECM) remodelling, and cell adhesion. Due to the well-documented melanoma–fibroblast crosstalk, Normal Human Fibroblasts (NHFs) and Cancer-Associated Fibroblasts (CAFs) were used as comparative references. Keratinocyte gene expression changes under the influence of melanoma secretome only partially overlapped with those of NHFs and CAFs, indicating cell-type-specific responses. Exposure to melanoma-conditioned medium induced the upregulation of bFGF, CXCL-16, TIMP-2, and E-cadherin in NHKs, alongside downregulating TGF-β and MMP-9. Although bFGF is a recognized pro-tumorigenic factor, the modulation of CXCL-16, TIMP-2, and TGF-β may reflect a protective response. Notably, under co-culture conditions, NHKs exhibited a pronounced pro-inflammatory and ECM-remodelling phenotype, characterized by elevated production of cytokines (IL-1α, IL-1β, and IL-8) and ECM-degrading enzymes (MMP-7, 9, 12, and 13), indicative of a pro-tumoral feature. Collectively, these findings underscore an active role for NHKs in melanoma initiation and progression.

Vitiligo is an acquired depigmentation disorder characterized by the selective destruction of melanocytes, resulting in the progressive loss of pigment in the skin and hair. This condition frequently leads to significant psychological distress. Its pathogenesis is complex and multifactorial, involving a combination of genetic susceptibility, metabolic derangement related to oxidative stress, defective melanocyte adhesion to the basal epidermis, and dysregulated innate and adaptive immune responses, ultimately converging in the targeted elimination of melanocytes. Despite the availability of several therapeutic modalities, current corrective options are often limited in efficacy and are associated with high relapse rates. There remains a pressing need for novel, safe, and more effective therapeutic strategies to improve patients’ quality of life. Growing evidence indicates that the immune system plays a pivotal role in vitiligo onset and progression, as most triggers converge on inflammatory and autoimmune pathways targeting melanocytes. However, immunosuppressive therapies alone have shown limited effectiveness in halting disease progression and achieving lasting repigmentation. Targeting only immunological processes without addressing the underlying triggers of their activation likely represents a significant limitation in restoring pigmentation. In contrast, interventions aimed at upstream events may help prevent the initiation of the immune response. Consequently, combinatorial therapeutic approaches that target multiple pathogenic pathways and incorporate diverse pharmacological agents are being explored to improve clinical outcomes. This review aims to re-evaluate the intrinsic cellular abnormalities and associated dysregulated signaling pathways in vitiligo, with the goal of identifying novel, effective, nonimmunological treatment strategies.

Basal cell carcinoma (BCC) is the most common skin cancer, predominantly affecting sun-exposed areas. It typically grows slowly and rarely metastasizes, though untreated cases can cause significant tissue destruction and morbidity. Its pathogenesis primarily involves dysregulation of the Hedgehog (HH) signaling pathway, mainly through mutations in PTCH1 or SMO genes, leading to chronic activation of downstream GLI transcription factors. Accordingly, current targeted therapies for locally advanced, unresectable, or metastatic BCC focus on SMO inhibition, using orally administered drugs such as vismodegib and sonidegib. Although these therapies have shown success, many patients develop resistance, with about 50% harboring mutated SMO. In numerous cases, genetic determinants (sometimes pre-existing) of resistance remain unidentified, complicating patient management. Here, we report a case of a 58-year-old female with advanced BCC who initially exhibited a favorable response to sonidegib but developed resistance after approximately one year. This resistance was not attributable to the acquired mutations in SMO but rather to intra-tumor heterogeneity and additional mutations in critical driver genes, including TP53, APC, FGFR1 and NOTCH1, which likely enable HH pathway inhibition. To our knowledge, this is the first report documenting a sonidegib resistance mechanism in BCC that is independent of HH pathway mutations. This case highlights the complexity of resistance mechanisms to HH inhibitors and underscores the critical need for comprehensive molecular tumor profiling prior to initiating targeted therapy.

Cutaneous melanoma is a highly aggressive skin cancer prone to relapse and metastasis. Surgery is often curative when combined with early screening and prevention. However, in recurrent or advanced disease, the development of new targeted and immune therapies has demonstrated promising clinical outcomes, although the acquisition of resistance limits their effectiveness. Thus, new therapeutic approaches are needed. Emerging data indicate that the Hedgehog (Hh) pathway, which is essential for embryonic development, is aberrantly reactivated in melanoma and may represent a promising therapeutic target. Here, we demonstrate its chronic up-modulation in a panel of patient-derived cell lines and, by investigating the underlying molecular mechanisms, we excluded mutations in the principal components of the pathway. We observed reduced PTCH1 and SUFU repressors expression and GLI2 upregulation as common melanoma features. At the same time, copious SHH release, the principal PTCH1 ligand, evidenced autocrine Hh signaling activation. Consistently, a tendency of greater level of this factor resulted higher in the blood of patients compared to controls, confirming the relevance of ligand-dependent trigger in melanoma. The therapeutic potential of inhibiting the Hh pathway is highlighted by the reduced proliferation and migration observed in the presence of clinically approved pharmacological Hh antagonists. Profiling inflammatory mediators revealed significant modulation upon treatment with SMO inhibitors, possibly affecting chemotactic and immune functions. Collectively, these findings provide deeper insight into the role of the Hh pathway in melanoma and support the potential repurposing of Hh inhibitors as therapeutic agents for melanoma.