Single-cell RNA sequencing reveals the transcriptomic landscape of and potential targets for large and giant congenital melanocytic naevi

Abstract Background The pathogenesis of large and giant congenital melanocytic naevi (L/GCMN) remains poorly understood, presenting significant challenges for its treatment. To date, no treatment guidelines for L/GCMN have been established. Moreover, single-cell technologies have not been applied in L/GCMN research, impeding an understanding of the disease at the cellular level. Objectives To elaborate on the transcriptomic landscape of cells in the skin microenvironment of L/GCMN, explore the crucial molecular mechanisms of melanocyte pathological changes and investigate their interactions with other cells. Methods We used a combination of single-cell and bulk RNA sequencing of lesional and nonlesional skin samples from patients with L/GCMN and healthy skin samples. Moreover, we also conducted Western blotting, quantitative reverse transcription polymerase chain reaction, and immunohistochemical and multiplex immunofluorescence to validate our results. Additionally, we isolated primary naevomelanocytes and explored the impact of T-box transcription factor 2 (TBX2) on the biologic functions of naevomelanocytes. Results Patients with L/GCMN have a higher density of melanocytes and enhanced functions in melanin synthesis-related processes. TBX2 serves as a core transcription factor for a melanocyte subpopulation that is specifically expressed in GCMN. It is closely associated with the proliferation and melanin synthesis of naevomelanocytes. Additionally, abnormal activation of the pleiotrophin–protein tyrosine phosphatase receptor type Z1 and insulin-like growth factor 1 (IGF-1)–IGF-1 receptor signalling pathways was detected in L/GCMN melanocytes. Conclusions The study provides initial insights into the transcriptional landscape and cellular interaction networks of L/GCMN, laying a foundation for further exploration of its molecular mechanisms.