Oral nicotinamide was safe and effective in reducing the rates of new nonmelanoma skin cancers and actinic keratoses in high-risk patients. (Funded by the National Health and Medical Research Council; ONTRAC Australian New Zealand Clinical Trials Registry number, ACTRN12612000625875.).
Our results revealed that the previously developed scoring system does not predict NSN metastasis; however, it was found to be a powerful predictive tool for overall and disease-free survival in SN-positive melanoma patients.
The incidence of melanoma continues to rise globally and is increasing at a rate greater than any other cancer. To systematically search for new genes involved in melanomagenesis, we collated exome sequencing data from independent melanoma cohort datasets, including those in the public domain. We identified recurrent mutations that may drive melanoma growth, survival or metastasis, and which may hold promise for the design of novel therapies to treat melanoma. These included a frequent recurrent (i.e. hotspot) mutation in the 5' untranslated region of RPS27 in ~10% of samples. We show that the mutation expands the 5'TOP element, a motif known to regulate the expression of most of the ribosomal protein family, to which RPS27 belongs, and thus might sensitize the mutated transcript to growth-mediated regulation. This finding highlights not only the important role of non-protein coding genetic aberrations in cancer development but also their potential as novel therapeutic targets.
In Brief Objective: This study sought to investigate the impact of histopathologically measured excision margins and SNB on local and locoregional disease control in patients with primary cutaneous melanomas more than 4 mm thick. Background: Most current guidelines recommend at least a 2-cm surgical margin (which corresponds to a 16-mm histopathologic margin). These guidelines are based on limited evidence, mostly obtained in patients who did not have an SNB. Methods: Histopathologic tumor excision margins for clinically lymph node-negative patients with melanomas more than 4 mm thick, treated at Melanoma Institute Australia (1992–2009), were determined. Clinicopathologic predictors of local and locoregional disease-free survival were investigated. Results: There were 632 patients eligible for the study; of these, 397 (62.8%) had an SNB. The median histopathologic excision margin was 15 mm (interquartile range, 11.0–19.5 mm). After a median follow-up of 37 months, local and locoregional recurrences were observed in 48 (7.6%) and 159 (25.2%) patients, respectively. Excision margin as a continuous variable was a significant predictor of local [hazard ratio (HR), 0.91; P < 0.001) and locoregional (HR, 0.97; P = 0.042) tumor control on multivariate analyses. Patients with histopathologic margins 16 mm or less had worse local disease-free survival (HR, 2.41; P = 0.01). Patients who did not have an SNB were at higher risk of locoregional recurrence (HR, 1.67; P = 0.003). Conclusions: Histopathologically determined primary tumor excision margins more than 16 mm, corresponding to 2-cm surgical margins, were associated with better local control in patients with melanomas more than 4 mm thick. Patients achieved the best local and locoregional control when SNB was coupled with a more than 16-mm histologic excision margin. In patients with thick primary melanomas (>4 mm), guidelines for wide excision are based on low-level evidence, and the value of sentinel node biopsy (SNB) in improving locoregional control has not been adequately assessed. In a large, retrospective, single-institution series, margins more than 2 cm and SNB provided optimal local and locoregional control.
In this largest study to date of patients with DM who underwent SLN biopsy, the SLN-positive rate in patients with DM was lower than that in patients with conventional melanoma. The results indicated that DM type is associated significantly and independently with the time to recurrence and should be evaluated routinely in all patients with PCM. Cancer 2010. (c) 2010 American Cancer Society.
High density SNP arrays can be used to identify DNA copy number changes in tumors such as homozygous deletions of tumor suppressor genes and focal amplifications of oncogenes. Illumina Human CNV370 Bead chip arrays were used to assess the genome for unbalanced chromosomal events occurring in 39 cell lines derived from stage III metastatic melanomas. A number of genes previously recognized to have an important role in the development and progression of melanoma were identified including homozygous deletions of CDKN2A (13 of 39 samples), CDKN2B (10 of 39), PTEN (3 of 39), PTPRD (3 of 39), TP53 (1 of 39), and amplifications of CCND1 (2 of 39), MITF (2 of 39), MDM2 (1 of 39), and NRAS (1 of 39). In addition, a number of focal homozygous deletions potentially targeting novel melanoma tumor suppressor genes were identified. Because of their likely functional significance for melanoma progression, FAS, CH25H, BMPR1A, ACTA2, and TFG were investigated in a larger cohort of melanomas through sequencing. Nonsynonymous mutations were identified in BMPR1A (1 of 43), ACTA2 (3 of 43), and TFG (5 of 103). A number of potentially important mutation events occurred in TFG including the identification of a mini mutation "hotspot" at amino acid residue 380 (P380S and P380L) and the presence of multiple mutations in two melanomas. Mutations in TFG may have important clinical relevance for current therapeutic strategies to treat metastatic melanoma.
Brm is an ATPase subunit of the SWI/SNF chromatin-remodelling complex. Previously, we identified a novel hotspot mutation in Brm in human skin cancer, which is caused by exposure to ultraviolet radiation (UVR). As SWI/SNF is involved in DNA repair, we investigated whether Brm-/- mice had enhanced photocarcinogenesis. P53+/- and Brm-/-p53+/- mice were also examined as the p53 tumor suppressor gene is mutated early during human skin carcinogenesis. Mice were exposed to a low-dose irradiation protocol that caused few skin tumors in wild-type mice. Brm-/- mice with both p53 alleles intact had an increased incidence of skin and ocular tumors compared to Brm+/+p53+/+ controls. Brm loss in p53+/- mice did not further enhance skin or ocular cancer incidence beyond the increased photocarcinogenesis in p53+/- mice. However, the skin tumors that arose early in Brm-/- p53+/- mice had a higher growth rate. Brm-/- did not prevent UVR-induced apoptotic sunburn cell formation, which is a protective response. Unexpectedly, Brm-/- inhibited UVR-induced immunosuppression, which would be predicted to reduce rather than enhance photocarcinogenesis. In conclusion, the absence of Brm increased skin and ocular photocarcinogenesis. Even when one allele of p53 is lost, Brm has additional tumor suppressing capability.
A history of multiple PM was an independent predictor of improved survival for patients with metastatic melanoma. The results indicate that a history of multiple PMs should be incorporated into multivariate analyses of prognostic factors and treatment outcomes.
The role of microRNAs (miRNAs) in melanoma is unclear. We examined global miRNA expression profiles in fresh-frozen metastatic melanomas in relation to clinical outcome and BRAF mutation, with validation in independent cohorts of tumours and sera. We integrated miRNA and mRNA information from the same samples and elucidated networks associated with outcome and mutation. Associations with prognosis were replicated for miR-150-5p, miR-142-3p and miR-142-5p. Co-analysis of miRNA and mRNA uncovered a network associated with poor prognosis (PP) that paradoxically favoured expression of miRNAs opposing tumorigenesis. These miRNAs are likely part of an autoregulatory response to oncogenic drivers, rather than drivers themselves. Robust association of miR-150-5p and the miR-142 duplex with good prognosis and earlier stage metastatic melanoma supports their potential as biomarkers. miRNAs overexpressed in association with PP in an autoregulatory fashion will not be suitable therapeutic targets.
Abstract Cutaneous melanoma cell proliferation is a strong prognostic factor for distant metastasis free survival (DMFS). In the current study we tested if aberrant expression of a regulator both DNA replication and cell cycle progression, i.e. the protein phosphatase 2A subunit PR48, could be a driver of melanoma proliferation and progression. Quantitative analysis of PR48 mRNA expression revealed a strong correlation between low levels of expression and poor DMFS in a multivariate analysis (n=49, p=0.0007). In line with this, no or low PR48 protein expression was associated with poor overall survival in three independent samples sets of melanoma (n=339, P&lt;0.001), and reduced PR48 expression correlated with increased proliferation (P=0.0023). Functional analysis using over expression and knock down strategies in melanoma cell lines demonstrated that PR48 alters cdc6-cdt1 complex formation, regulates pRb phosphorylation status, and entry into the S-phase of the cycle progression. Ectopic PR48 expression decreased tumorigenicity of melanoma cells, and shRNA-mediated reduced PR48 expression increased tumor take and growth in nude mice. Our data demonstrate that PPP2R3B is a novel tumor suppressor gene in melanoma, whose loss of expression contributes increased proliferation and poor survival. Citation Format: Léon CL van Kempen, Jonathan Jarry, Mounib Elchebly, Margaret Redpath, Per-Henrík Edqvist, Fredrik Pontén, Richard Scolyer, Dirk Schadendorf, Celia M.T. Greenwood, Joost van den Oord, Alan Spatz. The protein phosphatase 2 subunit PR48 is a novel melanoma tumor suppressor gene. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1977. doi:10.1158/1538-7445.AM2013-1977
An activating BRAF (V600E) kinase mutation occurs in approximately half of melanomas. Recent clinical studies have demonstrated that vemurafenib (PLX4032) and dabrafenib, potent and selective inhibitors of mutant v-raf murine sarcoma viral oncogene homolog B1 (BRAF), exhibit remarkable activities in patients with V600 BRAF mutant melanomas. However, acquired drug resistance invariably develops after the initial treatment. Identification of acquired resistance mechanisms may inform the development of new therapies that elicit long-term responses of melanomas to BRAF inhibitors. Here we report that increased expression of AEBP1 (adipocyte enhancer-binding protein 1) confers acquired resistance to BRAF inhibition in melanoma. AEBP1 is shown to be highly upregulated in PLX4032-resistant melanoma cells because of the hyperactivation of the PI3K/Akt-cAMP response element-binding protein (CREB) signaling pathway. This upregulates AEBP1 expression and thus leads to the activation of NF-κB via accelerating IκBa degradation. In addition, inhibition of the PI3K/Akt-CREB-AEBP1-NF-κB pathway greatly reverses the PLX4032-resistant phenotype of melanoma cells. Furthermore, increased expression of AEBP1 is validated in post-treatment tumors in patients with acquired resistance to BRAF inhibitor. Therefore, these results reveal a novel PI3K/Akt-CREB-AEBP1-NF-κB pathway whose activation contributes to acquired resistance to BRAF inhibition, and suggest that this pathway, particularly AEBP1, may represent a novel therapeutic target for treating BRAF inhibitor-resistant melanoma.
Read more9004 Background: MEK1 mutations can confer resistance to BRAF inhibitors although pre-existing MEK1P124 mutations do not preclude clinical responses to BRAF inhibitor therapy. We sought to determine if pre-existing MEK1P124 mutations affected clinical outcome in BRAF inhibitor treated melanoma. Methods: Data from three published data sets, and from patients treated at our institutions, were analyzed to determine if pre-existing MEKP124 mutations affect radiological response or progression-free survival (PFS) in BRAFV600 mutant metastatic melanoma patients treated with vemurafenib or dabrafenib. The effects of MEK1P124 mutations on MAPK pathway activity and response to dabrafenib were also investigated in a series of cell models. Results: 123 patients with pre-treatment tumors tested for MEK1 mutations were included. Those with a pretreatment MEKP124 mutation (n=12) had a poorer RECIST response (33% vs 71% CR or PR in MEK1P124 vs MEK1 wild-type, p=0.008), this was associated with a shorter median PFS in those with a MEK1P124 mutation (Median 3.1 vs 4.8 months, p=0.004). Introduction of MEK1 P124Q or P124S variants into BRAF-mutant SKMel28 melanoma cells resulted in diminished inhibition of ERK phosphorylation by dabrafenib and enhanced clonogenic survival compared to cells ectopically expressing wild-type MEK1. The impact of MEK1P124-variants was significantly less than the effect of MEK1K57E, a known mechanism of acquired BRAF inhibitor resistance. Consistent with these data, two BRAF mutant cell lines with endogenous MEK1P124 mutations, including a short term culture generated pre-treatment from a patient who responded poorly to combined dabrafenib and trametinib, showed weak sensitivity to dabrafenib (IC50s 21 and 26nM) compared to a panel of MEK1 wild type/BRAF mutant cell lines (median IC50 7nM; range 4-14nM). In contrast, melanoma cell lines showed equivalent sensitivity to ERK inhibition, irrespective of the MEK1 genotype. Conclusions: Pre-existing MEKP124 mutations are associated with a reduced response to BRAF inhibitor therapy but are unlikely to affect response to ERK inhibitors.
Read moreEruptive disseminated Spitz naevus (EDSN) is a rare entity and has never been documented in a South-east Asian individual (of Indian origin) previously. We report an adolescent with this condition which, to our knowledge, has only been previously reported a few times.
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