C-kit-mutated melanomas: the Chinese experience

Clinical Presentations of Melanoma in African Americans, Hispanics, and Asians

BACKGROUND

Skin cancer has traditionally been studied in Caucasian skin. Although it does occur with increased relative frequency in Caucasians, patients with skin of color suffer from elevated morbidity and mortality when diagnosed with skin cancer.

OBJECTIVE

To detail the unique demographic, clinical, and genetic features of melanoma in patients with skin of color, including Hispanic, African American, and Asian patients.

MATERIALS AND METHODS

A PubMed search was conducted spanning dates 1947 to June 2017. A total of 246 articles were screened, from which 69 were included in this review.

RESULTS

Relative to Caucasians, melanoma has unique demographic, clinical, and genetic features in African Americans, Hispanics, and Asians that include gender and subtype predominance.

CONCLUSION

Familiarization with these unique presentations of skin cancer in skin of color is imperative to accurate identification and treatment of cutaneous malignancies in these populations and ultimately to improved disease-related outcomes.

Analysis of Mucosal Melanoma Whole-Genome Landscapes Reveals Clinically Relevant Genomic Aberrations

PURPOSE

Unlike advances in the genomics-driven precision treatment of cutaneous melanomas, the current poor understanding of the molecular basis of mucosal melanomas (MM) has hindered such progress for MM patients. Thus, we sought to characterize the genomic landscape of MM to identify genomic alterations with prognostic and/or therapeutic implications.

EXPERIMENTAL DESIGN

Whole-genome sequencing (WGS) was performed on 65 MM samples, including 63 paired tumor blood samples and 2 matched lymph node metastases, with a further droplet digital PCR-based validation study of an independent MM cohort (n = 80). Guided by these molecular insights, the FDA-approved CDK4/6 inhibitor palbociclib was tested in an MM patient-derived xenograft (PDX) trial.

RESULTS

Besides the identification of well-recognized driver mutations of BRAF (3.1%), RAS family (6.2%), NF1 (7.8%), and KIT (23.1%) in MMs, our study also found that (i) mutations and amplifications in the transmembrane nucleoporin gene POM121 (30.8%) defined a patient subgroup with higher tumor proliferation rates; (ii) enrichment of structural variations between chromosomes 5 and 12 defined a patient subgroup with significantly worse clinical outcomes; (iii) over 50% of the MM patients harbored recurrent focal amplification of several oncogenes (CDK4, MDM2, and AGAP2) at 12q13-15, and this co-occurred significantly with amplification of TERT at 5p15, which was verified in the validation cohort; (iv) the PDX trial demonstrated robust antitumor effects of palbociclib in MMs harboring CDK4 amplification.

CONCLUSIONS

Our largest-to-date cohort WGS analysis of MMs defines the genomic landscape of this deadly cancer at unprecedented resolution and identifies genomic aberrations that could facilitate the delivery of precision cancer treatments.See related commentary by Shoushtari, p. 3473.

TERT copy gain predicts the outcome of high-dose interferon α-2b therapy in acral melanoma

Background

Asian populations are more likely to develop acral melanoma (AM) than Caucasians. The high-dose interferon (HD-IFN) α-2b regimen is the main adjuvant treatment for AM. TERT encodes the catalytic subunit of telomerase reverse transcriptase, which plays an important role in melanoma. Frequent TERT mutation and increased TERT gene expression have been described in AM. Our study aimed to investigate the status and the clinical significance of TERT copy number in a large cohort of patients with AM and to analyze the relationship between TERT copy number gain and the efficiency of HD-IFN.

Patients and methods

A total of 573 melanoma samples were retrospectively collected and analyzed for TERT copy number via Sanger sequencing. Clinical data of patients were also collected.

Results

TERT copy gain (copy number >2) was detected in 257 of the 573 patients with AM (44.9%). Of the 573 patients, 81 (14.1%) had a high copy gain (copy number >4). Patients with ulceration showed a significantly higher copy gain rate of TERT compared to the patients without ulceration (P=0.028). Patients with a tumor thicker than 4 mm also had a higher copy number rate of TERT than those with <4 mm (P=0.048). Our results showed that the overall survival (OS) was not significantly different between patients with and without TERT copy gain (P=0.890). However, among the 278 patients who received an HD-IFN regimen, Kaplan–Meier survival analysis demonstrated a significant correlation between TERT copy gain and relapse-free survival (RFS) (P=0.008). In addition, multivariate Cox regression assays validated TERT copy gain to be an independent prognostic factor of RFS for patients with AM undergoing HD-IFN therapy (hazard ratio =1.50; P=0.019).

Conclusion

The copy number status of TERT might be a predictor for HD-IFN efficacy, but it is not a prognostic factor of OS in patients with AM.

High G2 and S-phase expressed 1 expression promotes acral melanoma progression and correlates with poor clinical prognosis

G2 and S‐phase expressed 1 (GTSE1) regulates cell cycle progression in human cancers. However, its significance and mechanism of action in acral melanoma (AM) remain unknown. In the present study, we found that GTSE1 expression was upregulated in advanced stage/metastatic AM tissues and metastatic cell lines, and correlated with higher stage (P = .028) and poor disease‐free survival (DFS) in patients with AM (P = .003). Cox regression assays validated GTSE1 expression to be an independent prognostic factor of DFS for patients with AM (P = .004). Ectopic expression of GTSE1 enhanced primary AM cell proliferation, invasion, and migration. Loss‐of‐function in GTSE1 attenuated metastatic AM cell proliferation and metastatic ability in vitro and in vivo. We additionally observed that inhibition of migration and invasion occurred concomitantly with a GTSE1 knockdown‐mediated increase in E‐cadherin and decreases in N‐cadherin and Slug. We further showed that integrin subunit alpha 2 (ITGA2) interacts with GTSE1 and is a downstream effector of GTSE1. Further, ITGA2 levels were positively correlated with GTSE1 expression in human AM tissues. Ectopic ITGA2 expression rescued siGTSE1‐mediated inhibition of migration and invasion, thereby restoring epithelial‐to‐mesenchymal transition (EMT). In conclusion, GTSE1 expression promotes AM progression and correlates with clinical outcomes of patients with AM, and may represent a promising therapeutic target to suppress AM progression.

Mucosal melanoma: clinical, histological and c-kit gene mutational profile of 86 French cases

BACKGROUND

Mucosal melanomas are rare and highly aggressive tumours. Few studies evaluated mucosal melanomas of locations other than the head and neck region, and other than those of the Asian population.

OBJECTIVES

The objective of this study was to analyse the clinical and histological features, as well as the mutational status of c-kit and b-raf gene of mucosal melanoma in any localization in a French series.

METHODS

We investigated clinical (sex, age, performance status, survival, treatment of the patients and lack of pigmentation of the tumours) and histopathological features (ulceration, Breslow's index, mitotic rate), as well as the mutational status of c-kit and b-raf of 86 mucosal melanomas diagnosed in 15 years in four French University Hospitals.

RESULTS

Most melanomas affected women (72%) and the genital region (46.5%). A fifth of melanomas were amelanotic. 81% of melanomas had a Breslow's index ≥1, whereas all glans melanomas, and most vulvar melanomas had a Breslow index ≤1 mm. Overall survival was 54% at 3 years; 11.6% of the 43 tested mucosal melanomas were c-kit-mutated while the 15 tested genital melanomas were not. The c-kit gene mutation did not influence the overall survival. Age ≥ 50, amelanotic type and performance status ≥1 were not poor prognostic factors in our series.

CONCLUSION

This study confirmed that mucosal melanomas are rare and could be difficult to diagnose being often amelanotic and in hidden sites. Most melanomas were thick at the diagnosis, but glans and vulvar melanomas were thinner probably because of their greater visibility. The frequency of the c-kit mutation varied depending on the initial tumour site. In our series, the prognosis was poor, independently from c-kit mutations and the patient's general health and age. The presence of metastasis at diagnosis was associated with a worse prognosis indicating the importance of an early diagnosis.

Resveratrol inhibits alpha-melanocyte-stimulating hormone signaling, viability, and invasiveness in melanoma cells

Melanoma is a malignancy with high potential to invasion and treatment resistance. The α -melanocyte-stimulating hormone ( α -MSH) signal transduction involving Wnt/ β -catenin, c-Kit, and microphthalmia-associated transcription factor (MITF), a known pathway to produce melanin, has been demonstrated as one of cancer stem cell characteristics. This study was aimed to examine the effect of resveratrol, an abundant ingredient of grape and medicinal plants, on α -MSH signaling, viability, and invasiveness in melanoma cells. By α -MSH treatment, the melanin production in B16 melanoma cells was augmented as a validation for activation of α -MSH signaling. The upregulated expression of α -MSH signaling-related molecules β -catenin, c-Kit, and MITF was suppressed by resveratrol and/or STI571 treatment. Nuclear translocation of MITF, a hallmark of α -MSH signaling activation, was inhibited by combined treatment of resveratrol and STI571. At effective concentration, resveratrol and/or STI571 inhibited cell viability and α -MSH-activated matrix metalloproteinase- (MMP-)9 expression and invasion capacity of B16 melanoma cells. In conclusion, resveratrol enhances STI571 effect on suppressing the α -MSH signaling, viability, and invasiveness in melanoma cells. It implicates that resveratrol may have potential to modulate the cancer stem cell characteristics of melanoma.