The Journal of investigative dermatology最新文献

Lentigo maligna (LM), a type of in situ melanoma, has a high rate of local recurrence following surgical resection. Although recurrences might represent inadequately excised incident LMs, apparent recurrences could be new primary LMs developing from distinct melanocytic clones in the same ultraviolet radiation-damaged anatomical region. As distinguishing these possibilities has implications for patient management, we tested genetic relationships between incident and recurrent LMs. Incident LMs with histologically clear margins and their recurrent LMs and invasive lentigo maligna melanomas (LMMs) were laser microdissected for DNA extraction. Tumour and matched germline DNA underwent whole exome sequencing. Clonal relationships between incident and recurrent LMs were tested by elucidating and tracking clones within and across samples. Seven incident LMs with recurrent LM and four with recurrent LMM were sequenced. LM/LMMs had a high mutational burden, a predominant UVR signature, copy number alterations, and defects in DNA repair and cell cycle checkpoint regulator genes. All incident LMs were clonally related to their post-operative local recurrences. We found that local recurrences of LM commonly arise from subclinical residual disease after surgery. The mutational landscape of recurrent LM/LMMs was typical of melanomas arising from chronic sun exposure, but also displayed features described in late-stage melanomas.

Albinism is a heterogeneous inherited disorder with at least 21 known causative genes. Clinically, interpreting the potential digenic or oligogenic effects of the variants is a big challenge. We identified digenic mutations in a Chinese individual with oculocutaneous albinism (OCA), carrying a loss-of-function (LoF) mutation in the Cl^- channel gene OCA2 (c.808-3C>G) and an unreported gain-of-function (GoF) mutation in the Na⁺/Ca²⁺ channel gene TPCN2 (p.Ala24Val) which was confirmed by patch-clamp analysis. We further demonstrated that Cl^- bilaterally modulated TPC2 activity by patch-clamping: cytosolic high Cl^- inhibited but luminal high Cl^- enhanced TPC2 channel activity. Using CRISPR/Cas9-mediated knockout cell models and knockin mouse models, we confirmed that OCA2 modulated TPC2 activity by influencing melanosomal pH and pigment production. Mice mimicking double heterozygotes for the OCA2 LoF p.Val443Ile and the TPCN2 GoF p.Arg210Cys exhibited synergistic hypopigmentation in both fur and retina, phenocopying the albinism patient with digenic LoF OCA2 and GoF TPCN2 heterozygous mutations. This study provides experimental evidence supporting an oligogenic mode of inheritance in albinism, pinpoints melanosomal ion homeostasis as a key pathogenic mechanism and potential therapeutic target, and establishes a generalized research framework for elucidating gene-gene interactions in heterogeneous inherited disorders, especially for the channelopathies.

Squamous cell carcinomas arising in patients with recessive dystrophic epidermolysis bullosa are highly aggressive and often cause premature death. Current treatment options are limited, highlighting the need for innovative drug development concepts. Through transcriptome-guided computational drug screening, we identified selumetinib, a MAPK/extracellular signal-regulated kinase inhibitor, as a candidate drug for recessive dystrophic epidermolysis bullosa-associated squamous cell carcinomas. To verify the therapeutic potential of selumetinib against recessive dystrophic epidermolysis bullosa-associated squamous cell carcinomas, we assessed its efficacy in vitro and in vivo. In vitro, selumetinib decreased tumor cell viability, significantly reduced phosphorylation of extracellular signal-regulated kinase, and induced a mesenchymal-to-epithelial phenotypic shift, as indicated by increased E-cadherin and decreased vimentin expression. Functionally, it impaired tumor cell motility and invasion. Moreover, selumetinib significantly decreased PD-L1 and increased major histocompatibility complex class I levels and modulated the expression of immune-related cytokines. In vivo, selumetinib significantly suppressed tumor growth and reduced phosphorylated extracellular signal-regulated kinase levels in xenograft tumors. RNA sequencing identified EGR1 (early growth response protein 1), FOS (fos proto-oncogene), and DUSP6 (dual-specificity phosphatase 6) as candidate biomarkers of treatment response. Selumetinib, identified by computational drug screening, demonstrates efficacy against recessive dystrophic epidermolysis bullosa-associated squamous cell carcinomas in vitro and in vivo, suggesting its potential for clinical use.

Isotretinoin, the gold-standard treatment for severe acne, effectively targets major pathogenic factors but carries teratogenic risks. Its precise mechanism of action remains incompletely understood. Computational approaches, such as connectivity mapping, can offer insights into a drug's mechanism and identify alternative compounds as potential novel therapeutics for acne. In this study, we investigated the transcriptomic response in nonlesional skin of 18 patients with severe acne prior to isotretinoin therapy (baseline) and after 1, 8, and 20 weeks of therapy and 6 months after therapy. Our analysis revealed that isotretinoin induced significant early and sustained suppression of metabolic pathways, including oxidative phosphorylation, lipid metabolism, and mTORC1 signaling. Immunofluorescence staining in acne patient skin for phosphorylated S6, a downstream marker of mTORC1, corroborated decreased mTORC1 signaling as early as 1 week of therapy. In addition, connectivity mapping identified mTOR inhibitors as top candidates that mimic isotretinoin's transcriptomic signature. These findings enhance our understanding of isotretinoin's mechanism and highlight mTORC1 as a potential target for developing safer, nonteratogenic acne treatments.