Lnc-PKNOX1-1 inhibits tumor progression in cutaneous malignant melanoma by regulating NF-κB/IL-8 axis.

Cutaneous malignant melanoma is one of the most lethal cutaneous malignancies. Accumulating evidence has demonstrated the potential influence of long non-coding RNAs (lncRNAs) in biological behaviors of melanoma. Herein, we reported a novel lncRNA, lnc-PKNOX1-1 and systematically studied its functions and possible molecular mechanisms in melanoma. Reverse transcription-quantitative PCR assay showed that lnc-PKNOX1-1 was significantly decreased in melanoma cells and tissues. Low lnc-PKNOX1-1 expression was significantly correlated with invasive pathological type and Breslow thickness of melanoma. In vitro and in vivo experiments showed lnc-PKNOX1-1 dramatically inhibited melanoma cell proliferation, migration and invasion. Mechanically, protein microarray analysis suggested that interleukin-8 (IL-8) was negatively regulated by lnc-PKNOX1-1 in melanoma, which was confirmed by western blot and ELISA. Western blot analysis also showed that lnc-PKNOX1-1 could promote p65 phosphorylation at Ser536 in melanoma. Subsequent rescue assays proved IL-8 overexpression could partly reverse the tumor-suppressing function of lnc-PKNOX1-1 overexpression in melanoma cells, indicating that lnc-PKNOX1-1 suppressed the development of melanoma by regulating IL-8. Taken together, our study demonstrated the tumor-suppressing ability of lnc-PKNOX1-1 in melanoma, suggesting its potential as a novel diagnostic biomarker and therapeutic target for melanoma.

m6A Methyltransferase METTL3 Promotes the Progression of Primary Acral Melanoma via Mediating TXNDC5 Methylation.

m6A modification is one of the most important post-transcriptional modifications in RNA and plays an important role in promoting translation or decay of RNAs. The role of m6A modifications has been highlighted by increasing evidence in various cancers, which, however, is rarely explored in acral melanoma. Here, we demonstrated that m6A level was highly elevated in acral melanoma tissues, along with the expression of METTL3, one of the most important m6A methyltransferase. Besides, higher expression of METTL3 messenger RNA (mRNA) correlated with a higher stage in primary acral melanoma patients. Knockdown of METTL3 decreased global m6A level in melanoma cells. Furthermore, METTL3 knockdown suppressed the proliferation, migration, and invasion of melanoma cells. In METTL3 knockdown xenograft mouse models, we observed decreased volumes and weights of melanoma tissues. Mechanistically, we found that METTL3 regulates certain m6A-methylated transcripts, thioredoxin domain containing protein 5 (TXNDC5), with the confirmation of RNA-seq, MeRIP-seq, and Western blot. These data suggest that METTL3 may play a key role in the progression of acral melanoma, and targeting the m6A dependent-METTL3 signaling pathway may serve as a promising therapeutic strategy for management of patients of acral melanomas.

Identification of KRAS mutation in a patient with linear nevus sebaceous syndrome: a case report.

BACKGROUND: Linear nevus sebaceous syndrome (LNSS) is a rare genetic disease characterized by large linear sebaceous nevus typically on the face, scalp, or neck. LNSS could be accompanied by multisystem disorders including the central nervous system. Herein, we report gene mutational profile via whole exome sequencing of both lesional and non-lesional skin samples in a LNSS patient. CASE PRESENTATION: A 17-year-old girl presented with multisystem abnormalities, including large skin lesions, ocular disorders, abnormal bone development and neurological symptoms. A diagnosis of LNSS was established based on clinical manifestations, histopathological and imaging findings. The skin lesions were resected and no recurrence was noted at the time of drafting this report. Whole exome sequencing of genomic DNA revealed the following 3 mutations in the lesions of the index patient: KRAS (c.35G > A, p.G12D), PRKRIR (c.A1674T, p.R558S), and RRP7A (c. C670T, p.R224W), but no mutation was found in the healthy skin and peripheral blood sample of the index patient, or in the blood samples of her parents and sibling. PCR-mediated Sanger sequencing of DNA derived from lesional skin sample of the index patient verified KRAS mutation, but not PRKRIR (c.A1674T, p.R558S) and RRP7A (c. C670T, p.R224W). None of the 3 mutations was found in Sanger sequencing in skin lesions of 60 other cases of nevus sebaceous patients. CONCLUSIONS: Our findings show the relevance of KRAS mutation to LNSS, providing new clues in understanding related genetic heterogeneity which could aid genetic counselling for LNSS patients.