Nuclear Localization of Yes-Associated Protein Is Associated With Tumor Progression in Cutaneous Melanoma.

Yes-associated protein (YAP), an effector molecule of the Hippo signaling pathway, is expressed at high levels in cutaneous melanoma. However, the role of YAP in melanoma progression according to cellular localization is poorly understood. Tissues from 140 patients with invasive melanoma were evaluated by immunohistochemistry. Flow cytometry, western blotting, viability assays, wound healing assays, verteporfin treatment, and xenograft assays were conducted using melanoma cell lines B16F1 and B16F10 subjected to YapS127A transfection and siYap knockdown. Nuclear YAP localization was identified in 63 tumors (45.0%) and was more frequent than cytoplasmic YAP in acral lentiginous and nodular subtypes (P = .007). Compared with cytoplasmic YAP melanomas, melanomas with nuclear YAP had higher mitotic activity (P = .016), deeper invasion (P < .001), and more frequently metastasized to lymph nodes (P < .001) and distant organs (P < .001). Patients with nuclear YAP melanomas had poorer disease-free survival (P < .001) and overall survival (P < .001). Nuclear YAP was an independent risk factor for distant metastasis (hazard ratio: 3.206; 95% CI, 1.032-9.961; P = .044). Proliferative ability was decreased in siYapB16F1 (P < .001) and siYapB16F10 (P = .001) cells and increased in YapS127AB16F1 (P = .003) and YapS127AB16F10 (P = .002) cells. Cell cycle analysis demonstrated relative G1 retention in siYapB16F1 (P < .001) and siYapB16F10 (P < .001) cells and S retention in YapS127AB16F1 cells (P = .008). Wound healing assays showed that Yap knockdown inhibited cell invasion (siYapB16F1, P = .001; siYapB16F10, P < .001), whereas nuclear YAP promoted it (YapS127AB16F, P < .001; YapS127AB16F1, P = .017). Verteporfin, a direct YAP inhibitor, reduced cellular proliferation in B16F1 (P = .003) and B16F10 (P < .001) cells. Proliferative effects of nuclear YAP were confirmed in xenograft mice (P < .001). In conclusion, nuclear YAP in human melanomas showed subtype specificity and correlated with proliferative activity and proinvasiveness. It is expected that YAP becomes a useful prognostic marker, and its inhibition may be a potential therapy for melanoma patients.

Genetic Characteristics of Primary Cutaneous Malignant Melanoma in Koreans Compared With Western Populations.

BACKGROUND/AIM: Cutaneous melanoma, a melanocyte malignancy, can be divided into many clinical subtypes that differ in presentation, demographics, and genetic profile. In this study, we used next-generation sequencing (NGS) analysis to review genetic alterations in 47 primary cutaneous melanomas in the Korean population and compared them to alterations from melanomas in Western populations. PATIENTS AND METHODS: We retrospectively reviewed clinicopathologic and genetic features of 47 patients diagnosed with cutaneous melanomas between 2019-2021 at Severance Hospital, Yonsei University College of Medicine. NGS analysis was performed at diagnosis to evaluate single nucleotide variations (SNVs), copy number variations (CNVs), and genetic fusions. Genetic features in Western cohorts of melanoma were then compared with previous studies performed in the USA: Cohort 1 (n=556), Cohort 2 (n=79), and Cohort 3 (n=38). RESULTS: The most common histological classification of melanoma was the acral lentiginous type (23/47, 48.9%). BRAF V600 mutation was most frequent (11/47, 23.4%), but was significantly lower compared to Cohort 1 (240/556, 43.2%) and Cohort 2 (34/79, 43.0%) (p=0.0300). CNV analysis identified amplifications in chromosomes 12q14.1-12q15 (11/47, 23.4%) including CDK4 and MDM2 genes and 11q13.3 (9/47, 19.2%) including CND1, FGF19, FGF3, and FGF4 genes more frequently in the present study population than Cohort 1 (p<0.0001). CONCLUSION: These results clearly demonstrated differences in genetic alterations between melanomas in Asian and Western populations. Therefore, BRAF V600 mutation should be considered a significant signaling pathway explaining melanoma pathogenesis occurrence in both Asian and Western populations, whereas loss of chromosome 9p21.3 is unique to melanomas in Western populations.