-
Matteo S Carlino,
Kavitha Gowrishankar,
Catherine A B Saunders,
Gulietta M Pupo,
Stephanie Snoyman,
Xu Dong Zhang,
Robyn Saw,
Therese M Becker, Richard F Kefford,
Georgina V Long,
Helen Rizos
[show abstract]
[hide abstract]
ABSTRACT: Inhibitors of the MAPKs, BRAF and MEK, induce tumor regression in the majority of patients with BRAF-mutant metastatic melanoma. The clinical benefit of MAPK inhibitors is restricted by the development of acquired resistance with half of those who benefit having progressed by 6-7 months and long-term responders uncommon. There remains no agreed treatment strategy on disease progression in these patients. Without published evidence, fears of accelerated disease progression on inhibitor withdrawal have led to the continuation of drugs beyond formal disease progression. We now demonstrate that treatment with MAPK inhibitors beyond disease progression can provide significant clinical benefit, and the withdrawal of these inhibitors led to a marked increase in the rate of disease progression in two patients. We also show that MAPK inhibitors retain partial activity in acquired resistant melanoma by examining drug-resistant clones generated to dabrafenib, trametinib or the combination of these drugs. All resistant sublines displayed a markedly slower rate of proliferation when exposed to MAPK inhibitors, and this coincided with a reduction in MAPK signalling, decrease in BrdU incorporation and S-phase inhibition. This cytostatic effect was also associated with diminished levels of cyclin D1 and p-pRb. Two short-term melanoma cultures generated from resistant tumour biopsies also responded to MAPK inhibition with comparable inhibitory changes in proliferation and MAPK signalling. These data provide a rationale for the continuation of BRAF and MEK inhibitors after disease progression and support the development of clinical trials to examine this strategy.
Molecular Cancer Therapeutics 05/2013; · 5.23 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Activation of the c-Kit receptor tyrosine kinase is rare in melanoma, but occurs in 20-40% of melanoma arising on mucosal membranes, acral skin, and skin with chronic sun-induced damage. Many activating c-Kit mutations have been shown to be highly sensitive to imatinib mesylate, although the majority of c-kit mutant melanoma patients eventually progress on this inhibitor. We examined acquired resistance to imatinib and the newer generation inhibitor nilotinib in resistant c-kit mutant melanoma sublines. Four imatinib-resistant and six nilotinib-resistant sublines had acquired additional, secondary c-Kit mutations. The secondary A829P c-Kit mutation rendered cells resistant to imatinib, but did not suppress the activity of the tyrosine kinase inhibitors nilotinib and dasatinib. Sublines with an additional T670I c-Kit mutation showed resistance to imatinib, nilotinib and dasatinib, but responded to sunitinib. The concurrent inhibition of the MAPK and PI3K pathways was also effective at promoting apoptosis in the parent and derived resistant sublines. Our data provide a rationale for treating melanoma patients progressing on imatinib or nilotinib with alternative RTK inhibitors or inhibitors targeting the MAPK and PI3K signalling cascades. This article is protected by copyright. All rights reserved.
Pigment Cell & Melanoma Research 04/2013; · 5.06 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Selective BRAF inhibitors (BRAFi) are the standard of care for the treatment of BRAF(V600) -mutant metastatic melanoma. We analyzed a unique set of serial triplicate human metastatic melanoma tumor biopsies to identify biomarkers of BRAFi response and resistance. Morphologic features and immunohistochemical biomarkers were analyzed in 37 metastatic melanoma biopsies at pre-treatment (PRE), early during treatment (EDT) and on progression (PROG) from 15 patients treated with a BRAFi and correlated with response and outcome. At EDT proliferative markers decreased regardless of response, whereas markers of cell death increased in responders. High expression of nuclear p27 at baseline was the strongest predictor of a poorer OS, and predicted worse response. The results show that BRAFi are universally anti-proliferative, regardless of clinical response, whereas markers of cell death increased only in responders. The addition of therapies targeting the cell cycle machinery may improve the response and duration of BRAFi, and investigation of the mechanisms of apoptosis may provide additional therapeutic targets. © 2013 John Wiley & Sons A/S.
Pigment Cell & Melanoma Research 04/2013; · 5.06 Impact Factor
-
Journal of Clinical Oncology 03/2013; · 18.37 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Activated oncogenes restrict cell proliferation and transformation by triggering a DNA damage-dependent senescence checkpoint in response to DNA hyper-replication. Here we show that loss of the p16(INK) (4a) cyclin dependent kinase inhibitor and melanoma tumour suppressor facilitates a DNA damage response after a hyper-replicative phase in human melanocytes. Unlike cells expressing activated oncogenes however, melanocytes depleted for p16(INK) (4a) display enhanced proliferation and an extended replicative lifespan in the presence of replication-associated DNA damage. Analysis of human benign naevi confirmed that DNA damage and loss of p16(INK) (4a) expression co-segregate closely. Thus, we propose that loss of p16(INK) (4a) facilitates tumourigenesis by promoting the proliferation of genetically unstable cells. © 2012 John Wiley & Sons A/S.
Pigment Cell & Melanoma Research 12/2012; · 5.06 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Activating mutations in the BRAF gene occur in approximately 50% of melanomas. More than 70% of BRAF mutations are V600E and 10-30% are V600K. Potent and selective BRAF inhibitors have demonstrated significant clinical benefits in patients with V600E and V600K BRAF-mutated melanoma. V600R mutations constitute approximately 3-7% of all BRAF mutations and the activity of BRAF inhibitors in patients with this mutation is unknown. We have treated 45 patients with V600 mutated melanoma including patients with V600R mutation between July 2011 and October 2012 with the selective BRAF inhibitor dabrafenib (n=43) or vemurafenib (n=2) via a compassionate access programme. The overall response rate was 50% for the whole population with a progression-free survival of 5.5months. Five objective responses were seen in six assessable patients with V600R BRAF mutation (n=9). Our experience suggests that patients with V600R BRAF mutations can be treated successfully with oral BRAF inhibitors, and molecular diagnostic assays should include detection of this type of mutation.
European journal of cancer (Oxford, England: 1990) 12/2012; · 4.12 Impact Factor
-
Suzanah C Boyd,
Branka Mijatov,
Gulietta M Pupo,
Sieu L Tran,
Kavitha Gowrishankar,
Heather M Shaw,
Colin R Goding,
Richard A Scolyer,
Graham J Mann, Richard F Kefford,
Helen Rizos,
Therese M Becker
[show abstract]
[hide abstract]
ABSTRACT: Approximately 50% of melanomas require oncogenic B-RAF(V600E) signaling for proliferation, survival, and metastasis, and the use of highly selective B-RAF inhibitors has yielded remarkable, although short-term, clinical responses. Reactivation of signaling downstream of B-RAF is frequently associated with acquired resistance to B-RAF inhibitors, and the identification of B-RAF targets may therefore provide new strategies for managing melanoma. In this report, we applied whole-genome expression analyses to reveal that oncogenic B-RAF(V600E) regulates genes associated with epithelial-mesenchymal transition in normal cutaneous human melanocytes. Most prominent was the B-RAF-mediated transcriptional repression of E-cadherin, a keratinocyte-melanoma adhesion molecule whose loss is intimately associated with melanoma invasion and metastasis. Here we identify a link between oncogenic B-RAF, the transcriptional repressor Tbx3, and E-cadherin. We show that B-RAF(V600E) induces the expression of Tbx3, which potently represses E-cadherin expression in melanocytes and melanoma cells. Tbx3 expression is normally restricted to developmental embryonic tissues and promoting cell motility, but it is also aberrantly increased in various cancers and has been linked to tumor cell invasion and metastasis. We propose that this B-RAF/Tbx3/E-cadherin pathway has a critical role in promoting the metastasis of B-RAF-mutant melanomas.Journal of Investigative Dermatology advance online publication, 29 November 2012; doi:10.1038/jid.2012.421.
Journal of Investigative Dermatology 11/2012; · 6.31 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: This study investigated the sensitivity and specificity of immunohistochemical (IHC) analysis using an anti-BRAF antibody to detect the presence of the BRAF V600E mutation in patients with metastatic melanoma. A total of 100 patients with American Joint Committee on Cancer stage IIIC unresectable or stage IV melanoma and who underwent tumor DNA BRAF mutation testing were selected. Paraffin-embedded, formalin-fixed melanoma biopsies were analyzed for the BRAF mutation status by independent, blinded observers using both conventional DNA molecular techniques and IHC with the novel BRAF V600E mutant-specific antibody, VE1. The antibody had a sensitivity of 97% (37/38) and a specificity of 98% (58/59) for detecting the presence of a BRAF V600E mutation. Of the BRAF-mutated cases, none of the non-V600E cases (including V600K) stained positive with the antibody (0/11). There were 5 cases with discordant BRAF mutation results. Additional molecular analysis confirmed the immunohistochemically obtained BRAF result in 3 cases, suggesting that the initial molecular testing results were incorrect. Two of these patients would not have received a BRAF inhibitor on the basis of the initial false-negative mutation testing result. Two cases remained discordant. The reported IHC method is an accurate, rapid, and cost-effective method for detecting V600E BRAF mutations in melanoma patients. Clinical use of the V600E BRAF antibody should be a valuable supplement to conventional mutation testing and allow V600E mutant metastatic melanoma patients to be triaged rapidly into appropriate treatment pathways.
The American journal of surgical pathology 09/2012; · 4.06 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: BACKGROUND: Little is known about the prevalence and clinical significance of heterogeneity of positron emission tomography with (18)F-labelled fluorodeoxyglucose-positron emission tomography (FDG-PET) response. We aim to determine the prevalence, and clinicopathologic correlates of intra-patient heterogeneity of FDG-PET response in metastatic melanoma treated with dabrafenib, and to determine whether heterogeneity predicts clinical outcome. METHODS: Patients with BRAF mutant metastatic melanoma and ⩾2 FDG avid lesions treated on the Phase I trial of dabrafenib at a single institution (n=23) were included. FDG-PET response was assessed by comparing baseline PET scans with scans at day 15. A heterogeneous response was defined as responding and new or metabolically progressing lesion(s) in a patient, or >10% of lesions with a stable metabolic response and responding lesions in a patient. RESULTS: Six (26%) patients had a heterogeneous PET response. The median time to progression (TTP) was 7.4months (95% confidence interval (CI): 6.5-8.3) for PET homogeneous responders and 3.0months (95%CI: 0.6-5.4) for PET heterogeneous responders. There were no homogeneous non-responders. Age, BRAF mutation genotype, dose, and lactate dehydrogenase, did not predict for heterogeneity of PET response. Heterogeneity did not correlate with tumour response. Lung metastases were more likely to respond than other visceral metastatic sites. CONCLUSIONS: Heterogeneous FDG-PET responses are common in metastatic melanoma treated with dabrafenib, and heterogeneity is associated with a shorter TTP. FDG-PET heterogeneity may predict molecular heterogeneity, and FDG-PET directed biopsies may facilitate investigation into mechanisms of resistance to signal pathway inhibitors.
European journal of cancer (Oxford, England: 1990) 09/2012; · 4.12 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Targeted therapies are increasingly being used to treat a variety of cancers. Their efficacy depends upon the accurate detection and targeting of a specific mutation or aberration in the tumour. All cancers such as melanoma are molecularly heterogeneous, with drug resistant subclones present prior to treatment or emerging as a result of targeted therapies. Here we show intra-lesional molecular heterogeneity in a progressing V600E BRAF-mutant melanoma metastasis from a patient treated for 7 months with the BRAF inhibitor vemurafenib. In the single metastasis, two distinct subclones were observed, both V600E BRAF-mutant, and only one with an additional G13R NRAS-mutation. Molecular heterogeneity even at the intra-lesional level demonstrates that personalising or adjusting therapies based on genotyping of a portion of a single lesion, might not accurately depict the molecular profile or drivers of oncogenesis across the entire patient's melanoma.
Molecular Cancer Therapeutics 09/2012; · 5.23 Impact Factor
-
Graham J Mann,
Gulietta M Pupo,
Anna E Campain,
Candace D Carter,
Sarah-Jane Schramm,
Svetlana Pianova,
Sebastien K Gerega,
Chitra De Silva,
Kenneth Lai,
James S Wilmott,
Maria Synnott,
Peter Hersey, Richard F Kefford,
John F Thompson,
Yee Hwa Yang,
Richard A Scolyer
[show abstract]
[hide abstract]
ABSTRACT: Prediction of outcome for melanoma patients with surgically resected macroscopic nodal metastases is very imprecise. We performed a comprehensive clinico-pathologic assessment of fresh-frozen macroscopic nodal metastases and the preceding primary melanoma, somatic mutation profiling, and gene expression profiling to identify determinants of outcome in 79 melanoma patients. In addition to disease stage <II at initial presentation, the following clinical and pathologic factors were independent predictors of improved outcome (odds ratios for survival >4 years, 90% confidence interval): the presence of a nodular component in the primary melanoma (6.8, 0.6-76.0), and small cell size (11.1, 0.8-100.0) or low pigmentation (3.0, 0.8-100.0) in the nodal metastases. Absence of BRAF mutation (20.0, 1.0-1000.0) or NRAS mutation (16.7, 0.6-1000.0) were both favorable prognostic factors. A 46-gene expression signature with strong overrepresentation of immune response genes was predictive of better survival (10.9, 0.4-325.6); in the full cohort, median survival was >100 months in those with the signature, but 10 months in those without. This relationship was validated in two previously published independent stage III melanoma data sets. We conclude that the presence of BRAF mutation, NRAS mutation, and the absence of an immune-related expressed gene profile predict poor outcome in melanoma patients with macroscopic stage III disease.Journal of Investigative Dermatology advance online publication, 30 August 2012; doi:10.1038/jid.2012.283.
Journal of Investigative Dermatology 08/2012; · 6.31 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The incidence of melanoma in Australia continues to rise. Early diagnosis and management before the melanoma has metastasised provides the best opportunity for a favourable outcome.
This article discusses the management of melanoma once a clinical diagnosis has been made.
If melanoma is suspected, initial excision biopsy is recommended. Wide excision margins are then based on reported tumour thickness. Sentinel lymph node biopsy provides important prognostic information and a probable survival benefit for patients with intermediate thickness melanomas. Other staging tests are not indicated in patients with clinically localised primary melanomas. Complete lymph node dissection is required if microscopic or macroscopic disease is present in regional nodes. Intransit metastases are best managed at specialist melanoma treatment centres. For patients with widespread systemic metastases, new drug treatments including BRAF inhibitors and anti-CTLA4 antibodies are prolonging survival, but unfortunately most patients ultimately relapse.
Australian family physician 07/2012; 41(7):470-3. · 0.73 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A history of multiple primary melanomas (PMs) has been associated with improved survival in patients with early stage melanoma, but whether it also is correlated with survival in patients with metastatic melanoma is unknown. The authors sought to address the latter question in the current study.
Patients with metastatic melanoma diagnosed at the Melanoma Institute Australia between 1983 and 2008 were identified. Overall survival (OS) was calculated from date of first distant metastasis. Survival analysis was performed using the Kaplan-Meier method, log-rank tests, and multivariate Cox proportional hazards models.
Of 2942 patients with metastatic melanoma, 2634 (89.5%) had 1 PM and 308 (10.5%) had >1 PM. Factors that were associated independently with shorter OS were site of metastasis, including the brain (hazard ratio [HR], 2.41; 95% confidence interval [CI], 2.07-2.81; P < .001) and nonlung viscera (HR, 1.92; 95% CI, 1.67-2.22; P < .001, vs lymph node/subcutaneous/soft tissue), age >60 years (HR, 1.23; 95% CI, 1.12-1.36; P < .001), shorter disease-free interval from PM to first distant metastasis (≤12 months vs >36 months: HR, 1.62; 95% CI, 1.39-1.89; P < .001), and fewer PMs (1 vs >1; HR, 1.26; 95% CI, 1.08-1.47; P = .004).
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. Cancer 2012. © 2012 American Cancer Society.
Cancer 06/2012; 118(18):4519-29. · 4.77 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Certain clinicopathologic features correlate with BRAF mutation status in melanoma including younger age and primary subtype. This study sought to determine the BRAF mutation status by age-decade and whether BRAF-mutant genotypes correlated with clinicopathologic features and outcome in patients with metastatic melanoma. Methods: A prospectively assembled cohort of Australian patients were followed from diagnosis of metastatic melanoma (N = 308). Clinicopathologic variables were correlated with BRAF mutational status, genotype, and survival.
Forty-six percent of patients had a BRAF mutation; 73% V600E, 19% V600K, and 8% other genotypes. An inverse relationship existed between BRAF mutation prevalence and age-decade (P < 0.001). All patients <30 years and only 25% ≥ 70 years had BRAF-mutant melanoma. Amongst BRAF-mutant melanoma, the frequency of non-V600E genotypes (including V600K) increased with increasing age. Non-V600E genotypes comprised <20% in patients <50 years and >40% in those ≥ 70 years. A higher degree of cumulative sun-induced damage correlated with V600K but not V600E melanoma (P = 0.002). The disease-free interval from diagnosis of primary melanoma to first distant metastasis was shorter for patients with V600K compared with V600E melanoma (17.4 vs. 39.2 months, P = 0.048), with no difference in survival thereafter. In patients BRAF tested at diagnosis of metastatic melanoma, one year survival from diagnosis of metastasis was significantly longer for patients with BRAF-mutant melanoma treated with an inhibitor (83%), than those not treated with an inhibitor (29%, P < 0.001), or patients with BRAF wild-type melanoma (37%, P < 0.001).
Different genotypes exist within BRAF-mutant metastatic melanoma, representing biologically and clinically discrete subtypes, suggesting distinct etiology and behavior.
Clinical Cancer Research 04/2012; 18(12):3242-9. · 7.74 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Cellular senescence permanently restricts the replicative capacity of cells in response to various stress signals, including aberrant activation of oncogenes. The presence of predictive senescence markers in human premalignant lesions suggests that senescence may function as a genuine tumor suppressor. These markers are not exclusive to the senescence program, however, and it is possible that their expression in vivo does not discriminate irreversible from reversible forms of proliferative arrest. In this study, we aimed to clarify whether human nevus cells can be distinguished from primary and transformed melanocytes by examining the expression of eight senescence markers, including those previously purported to define nevi as senescent tumors. Specifically, we analyzed effectors of senescence, including p16(INK4a), p53, and DNA damage (γ-H2AX), as well as predictive markers of senescence including Ki67, PML, senescence-associated β-galactosidase, heterochromatic foci (H3K9Me, 4'-6-diamidino-2-phenylindole), and nuclear size. We found that these commonly accepted senescence markers do not in fact distinguish nevi from precursor/normal and transformed/malignant melanocytes. We conclude that on the basis of current evidence it cannot be reasonably inferred that nevi are permanently growth arrested via senescence.
Journal of Investigative Dermatology 04/2012; 132(9):2226-34. · 6.31 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Aberrant activation of the BRAF kinase occurs in ∼60% of melanomas, and although BRAF inhibitors have shown significant early clinical success, acquired resistance occurs in most patients. Resistance to chronic BRAF inhibition often involves reactivation of mitogen-activated protein kinase (MAPK) signaling, and the combined targeting of BRAF and its downstream target MAPK/ERK kinase (MEK) may delay or overcome resistance. To investigate the efficacy of combination BRAF and MEK inhibition, we generated melanoma cell clones resistant to the BRAF inhibitor GSK2118436. These BRAF inhibitor-resistant sublines acquired resistance through several distinct mechanisms, including the acquisition of activating N-RAS mutations and increased accumulation of COT1. These alterations uniformly promoted MAPK reactivation and most conferred resistance to MEK inhibition and to the concurrent inhibition of BRAF and MEK. These data indicate that melanoma tumors are likely to develop heterogeneous mechanisms of resistance, many of which will confer resistance to multiple MAPK inhibitory therapies.
Journal of Investigative Dermatology 03/2012; 132(7):1850-9. · 6.31 Impact Factor
-
Rajmohan Murali,
Lauren E Haydu,
Georgina V Long,
Michael J Quinn,
Robyn P M Saw,
Kerwin Shannon,
Andrew J Spillane,
Jonathan R Stretch, Richard F Kefford,
John F Thompson,
Richard A Scolyer
[show abstract]
[hide abstract]
ABSTRACT: Approximately 3-5% of patients with thin (≤ 1 mm) cutaneous melanomas develop distant metastases. We sought to identify clinical and pathologic factors associated with distant metastasis and survival in a large number of patients with thin melanoma treated at a single institution.
We identified patients with a single invasive melanoma ≤ 1 mm in thickness diagnosed between January 1983 and December 2003 who developed distant metastasis (cases), and matched patients with no recorded recurrence during follow-up (control subjects). Cases and control subjects were matched for age, sex, and year of primary melanoma diagnosis. Associations of clinical and pathologic parameters with distant metastasis-free survival and melanoma-specific survival were analyzed.
A total of 178 cases and 178 control subjects were identified. Factors associated with development of distant metastasis were: increasing Breslow thickness (P < 0.001), increasing Clark level of invasion (P < 0.001), increasing mitotic rate (P = 0.001), ulceration (P = 0.025), and American Joint Committee on Cancer T subcategory (P < 0.001). Multivariable models including Breslow thickness (but not Clark level) showed that factors independently associated with poorer distant metastasis-free survival were increasing age [hazard ratio (HR) 1.01, 95% confidence interval (CI) 1.00-1.02]; increasing Breslow thickness (HR 3.21, 95% CI 1.73-5.94, and HR 3.77, 95% CI 2.11-6.74 for 0.51-0.75 mm and 0.76-1.00 mm, respectively, compared with 0.01-0.50 mm); ulceration (HR 1.87, 95% CI 1.14-3.06) and mitotic rate (HR 1.13, 95% CI 1.05-1.21). Similar associations with melanoma-specific survival were found.
Clinical and pathologic predictors of distant metastasis and survival identified in this large study of patients with thin primary cutaneous melanomas will enable more accurate stratification of risk of distant metastasis and poor survival in such patients, and will assist in formulating clinical management and follow-up regimens based on the level of risk.
Annals of Surgical Oncology 02/2012; 19(6):1782-9. · 4.17 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: To evaluate the effects of treatment with the potent mutant BRAF inhibitors GSK2118436 or vemurafenib (PLX4720) on immune responses to metastatic melanoma in tissues taken before and after treatment.
Thirty-seven tumor biopsies were collected from 15 patients with unresectable American Joint Committee on Cancer stage III or IV melanoma immediately before and approximately 7 days after the commencement of BRAF inhibitor treatment and at the time of tumor progression. Immunohistochemical staining was carried out on the biopsies using specific antibodies for CD8, CD4, CD20, CD1a, and Granzyme B.
Tumor infiltration by CD4(+) and CD8(+) lymphocytes increased markedly following BRAF inhibitor treatment (both ρ = 0.015). There was a correlation between the degree of tumor infiltration by CD8(+) and Granzyme B-expressing lymphocytes in post-BRAF inhibitor-treated biopsies (r = 0.690 and ρ = 0.013). Increased intratumoral CD8(+) lymphocyte expression was correlated with a reduction in tumor size and an increase in necrosis in posttreatment biopsies (r = -0.793, ρ = 0.011; and r = 0.761, ρ = 0.004, respectively).
The increase in tumor-infiltrating lymphocytes induced by treatment with BRAF inhibitors provides strong support for conducting trials that combine BRAF inhibitors with immunotherapy in the hope of prolonging clinical responses.
Clinical Cancer Research 12/2011; 18(5):1386-94. · 7.74 Impact Factor
-
Anne E Cust,
Chris Goumas,
Elizabeth A Holland,
Chantelle Agha-Hamilton,
Joanne F Aitken,
Bruce K Armstrong,
Graham G Giles, Richard F Kefford,
Helen Schmid,
John L Hopper,
Graham J Mann,
Mark A Jenkins
[show abstract]
[hide abstract]
ABSTRACT: The contribution of melanocortin-1 receptor (MC1R) gene variants to the development of early-onset melanoma is unknown. Using an Australian population-based, case-control-family study, we sequenced MC1R for 565 cases with invasive cutaneous melanoma diagnosed between ages 18 and 39 years, 409 unrelated controls and 518 sibling controls. Variants were classified a priori into "R" variants (D84E, R142H, R151C, I155T, R160W, D294H) and "r" variants (all other nonsynonymous variants). We estimated odds ratios (OR) for melanoma using unconditional (unrelated controls) and conditional (sibling controls) logistic regression. The prevalence of having at least one R or r variant was 86% for cases, 73% for unrelated controls and 81% for sibling controls. R151C conferred the highest risk (per allele OR 2.57, 95% confidence interval 1.86-3.56 for the case-unrelated-control analysis and 1.70 (1.12-2.60) for the case-sibling-control analysis). When mutually adjusted, the ORs per R allele were 2.23 (1.77-2.80) and 2.06 (1.47-2.88), respectively, from the two types of analysis, and the ORs per r allele were 1.69 (1.33-2.13) and 1.25 (0.88-1.79), respectively. The associations were stronger for men and those with none or few nevi or with high childhood sun exposure. Adjustment for phenotype, nevi and sun exposure attenuated the overall log OR for R variants by approximately 18% but had lesser influence on r variant risk estimates. MC1R variants explained about 21% of the familial aggregation of melanoma. Some MC1R variants are important determinants of early-onset melanoma. The strength of association with melanoma differs according to the type and number of variants.
International Journal of Cancer 11/2011; 131(3):E269-81. · 5.44 Impact Factor
-
Satoru Yokoyama,
Susan L Woods,
Glen M Boyle,
Lauren G Aoude,
Stuart MacGregor,
Victoria Zismann,
Michael Gartside,
Anne E Cust,
Rizwan Haq,
Mark Harland, [......],
Julia A Newton-Bishop,
Grant W Montgomery,
Nicholas G Martin,
Graham J Mann,
D Timothy Bishop,
Hensin Tsao,
Jeffrey M Trent,
David E Fisher,
Nicholas K Hayward,
Kevin M Brown
[show abstract]
[hide abstract]
ABSTRACT: So far, two genes associated with familial melanoma have been identified, accounting for a minority of genetic risk in families. Mutations in CDKN2A account for approximately 40% of familial cases, and predisposing mutations in CDK4 have been reported in a very small number of melanoma kindreds. Here we report the whole-genome sequencing of probands from several melanoma families, which we performed in order to identify other genes associated with familial melanoma. We identify one individual carrying a novel germline variant (coding DNA sequence c.G1075A; protein sequence p.E318K; rs149617956) in the melanoma-lineage-specific oncogene microphthalmia-associated transcription factor (MITF). Although the variant co-segregated with melanoma in some but not all cases in the family, linkage analysis of 31 families subsequently identified to carry the variant generated a log of odds (lod) score of 2.7 under a dominant model, indicating E318K as a possible intermediate risk variant. Consistent with this, the E318K variant was significantly associated with melanoma in a large Australian case-control sample. Likewise, it was similarly associated in an independent case-control sample from the United Kingdom. In the Australian sample, the variant allele was significantly over-represented in cases with a family history of melanoma, multiple primary melanomas, or both. The variant allele was also associated with increased naevus count and non-blue eye colour. Functional analysis of E318K showed that MITF encoded by the variant allele had impaired sumoylation and differentially regulated several MITF targets. These data indicate that MITF is a melanoma-predisposition gene and highlight the utility of whole-genome sequencing to identify novel rare variants associated with disease susceptibility.
Nature 11/2011; 480(7375):99-103. · 36.28 Impact Factor
