Introduction

Melanoma originates from pigment-producing melanocytes, which can be found in the skin, eyes, inner ear and soft brain membranes. Genetic variants have been identified as a contributor in such a process. As a kind of malignant tumor, cutaneous malignant melanoma is considered the most aggressive (prone to spread) and fatal skin cancer with a collapsed prognosis which reveals a high possibility of metastasis, although it only accounts for 1% of all skin malignancies. Currently, an integrative therapeutic strategy has been applied in the administration of tumor, including surgical removal, chemotherapy, radiotherapy, photodynamic therapy, immunotherapy or cell therapy [1]. Immunotherapy presents great potential in the advanced management of malignant tumors, but the immune microenvironment is critical in deciding the outcomes of immunotherapy. Thus, beyond histological classification, immunological analysis would be essential for melanoma.

Based on histological analysis, VuM is predominantly superficially diffuse, nodular and acral freckle type, while VaM is predominantly nodular [2, 3]. Superficially diffuse melanoma demonstrates a relatively better prognosis, whereas nodular melanoma indicates a poor prognosis [2]. Generally, VuM and VaM are often subject to delayed diagnoses, and most cases remain undetected until they have progressed to an advanced stage. Female genital tract associated melanoma only consists of 1–3% affected population, and most of them are located in vulva area (76%) [4]. The five-year survival rate of VuM and VaM varies between 10% and 50% [5]. Moreover, a high ratio of local and distant metastases is usually identified in VuM patients, with a high incidence of drug resistance, indicating a terrible prognosis [2, 6].

scRNA-seq has its unique advantage of maximizing tissue heterogeneity owing to unbiased assessment of single-cell expression profile [41]. The challenges in eradicating melanoma stem from its inherent heterogeneity and adaptability. Melanoma exhibits significant heterogeneity in terms of cell composition, chromosomal structure, developmental trajectories, intercellular signaling networks, and phenotypic dominance. By analyzing metabolic gene expression profiles in the tumor microenvironment using single-cell expression data, researchers can uncover metabolic characteristics and pathways that distinguish tumor metabolic heterogeneity at the single-cell level from that at the tissue level. This approach enables the determination of tumor microenvironment heterogeneity by re-subty** and identifying cellular features, including phenotypic abundance, genetic alterations, immune dynamics, clonal expansion, developmental trajectories, and molecular interactions [42]. These factors have the potential to influence patient prognosis and treatment outcomes, providing invaluable insights into melanoma treatment strategies [43]. A significant portion (40-50%) of malignant melanoma arises from immune-related antigens, such as T cell-granulocyte expression of PD-1, CD8+, CD4+ T, and NK T lymphocyte-granulocytes. Combining PD-1/PD-L1 inhibitors with Toll-like receptor agonists has been extensively studied as a combination therapy in clinical practice. Immuno-infiltration therapy aims to enhance the immune response against tumor-associated antigens or autoantibodies. While T lymphocytes can directly eliminate tumor cells, it is crucial to disrupt the balance of CD8+ T and NK lymphocytes-granulocytes within the tumor to prevent malignant melanoma metastasis recurrence. This can be achieved by activating CD8+ T lymphocytes-granulocytes through antigen recognition receptors or ligands, a process known as anti-demethlicity. Another approach involves obtaining resistant T lymphocytes-granulocytes by adding or removing antigens in immunodeficient mouse allografts. PD-1/PD-L1 inhibitors have demonstrated efficacy in the treatment of non-metastatic melanoma and various other malignancies. Currently, PD-1/PD-L1 inhibitors are approved for the treatment of melanoma, bladder cancer, and other malignancies. Thus, the scRNA-seq revealed the significance of immune responses involved in cellular communication contributing to micro-environment formation in melanoma. And the cellular interaction induced several antigens’ high expression which participated in the immunological escape of cancer cells and the failure of chemical therapy. So, the identified results demonstrated the importance of immunological regulation or modification in melanoma management. Although this was only a case report which contained limited data and samples. However, the results still provided clinical implications but more than 10 thousand cellular interaction analysis, indicating a further research topic hitting the immunological regulation or immunotherapy in melanoma.

There are still many limitations in this study. Firstly, the sample size was relatively small, consisting of only one specimen. Furthermore, when comparing our data to other datasets such as The Cancer Genome Atlas (TCGA) and other single-cell datasets, it is crucial to consider potential confounding factors arising from technical and batch effects, emphasizing the need for cautious interpretation. To address these limitations, we plan to increase the sample size in our follow-up study to ensure the reproducibility of our conclusions. To further validate the critical role of CD8+ T cells, we will use PD-1/PD-L1 inhibitors to treat human VuM cells. By scratch assay and transwell invasion assay, we can verify the effect of CD8+Tcell on the VuM cells migration. Ho** experiment results provide a new reference for VuM targeting treatment.

Conclusion

In conclusion, the characterization of melanoma at the cellular and molecular levels has provided valuable insights into its heterogeneity, tumor microenvironment, and potential therapeutic targets. Studies examining single-cell expression data have revealed transcriptional signatures of various cell types, allowing for the identification of specific markers and pathways involved in melanoma progression and metastasis. Besides, the immunological microenvironmental regulation had been supposed to be involved in the formation and growth of melanoma, and corresponding molecules on the identified antigens presented a promising therapeutic strategy. Furthermore, the identification of genetic alterations, metabolic characteristics, and molecular interactions within the tumor microenvironment provides valuable information for personalized treatment approaches and prognostic predictions. l.