| 1. |
- Azimi, Alireza, et al.
(author)
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Targeting CDK2 overcomes melanoma resistance against BRAF and Hsp90 inhibitors
- 2018
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In: Molecular Systems Biology. - : EMBO. - 1744-4292. ; 14:3
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Journal article (peer-reviewed)abstract
- Novel therapies are undergoing clinical trials, for example, the Hsp90 inhibitor, XL888, in combination with BRAF inhibitors for the treatment of therapy-resistant melanomas. Unfortunately, our data show that this combination elicits a heterogeneous response in a panel of melanoma cell lines including PDX-derived models. We sought to understand the mechanisms underlying the differential responses and suggest a patient stratification strategy. Thermal proteome profiling (TPP) identified the protein targets of XL888 in a pair of sensitive and unresponsive cell lines. Unbiased proteomics and phosphoproteomics analyses identified CDK2 as a driver of resistance to both BRAF and Hsp90 inhibitors and its expression is regulated by the transcription factor MITF upon XL888 treatment. The CDK2 inhibitor, dinaciclib, attenuated resistance to both classes of inhibitors and combinations thereof. Notably, we found that MITF expression correlates with CDK2 upregulation in patients; thus, dinaciclib would warrant consideration for treatment of patients unresponsive to BRAF-MEK and/or Hsp90 inhibitors and/or harboring MITF amplification/overexpression.
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| 2. |
- Barrett, Jennifer H., et al.
(author)
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Genome-wide association study identifies three new melanoma susceptibility loci
- 2011
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In: Nature Genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 43:11, s. 1108-1113
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Journal article (peer-reviewed)abstract
- We report a genome-wide association study for melanoma that was conducted by the GenoMEL Consortium. Our discovery phase included 2,981 individuals with melanoma and 1,982 study-specific control individuals of European ancestry, as well as an additional 6,426 control subjects from French or British populations, all of whom were genotyped for 317,000 or 610,000 single-nucleotide polymorphisms (SNPs). Our analysis replicated previously known melanoma susceptibility loci. Seven new regions with at least one SNP with P < 10(-5) and further local imputed or genotyped support were selected for replication using two other genome-wide studies (from Australia and Texas, USA). Additional replication came from case-control series from the UK and The Netherlands. Variants at three of the seven loci replicated at P < 10(-3): an SNP in ATM (rs1801516, overall P = 3.4 x 10(-9)), an SNP in MX2 (rs45430, P = 2.9 x 10-9) and an SNP adjacent to CASP8 (rs13016963, P = 8.6 x 10(-10)). A fourth locus near CCND1 remains of potential interest, showing suggestive but inconclusive evidence of replication (rs1485993, overall P = 4.6 x 10(-7) under a fixed-effects model and P = 1.2 x 10(-3) under a random-effects model). These newly associated variants showed no association with nevus or pigmentation phenotypes in a large British case-control series.
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| 3. |
- Das, Ishani, et al.
(author)
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Inhibiting insulin and mTOR signaling by afatinib and crizotinib combination fosters broad cytotoxic effects in cutaneous malignant melanoma
- 2020
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In: Cell Death and Disease. - : Springer Nature. - 2041-4889. ; 11:10
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Journal article (peer-reviewed)abstract
- Current treatment modalities for disseminated cutaneous malignant melanoma (CMM) improve survival, however disease progression commonly ensues. In a previous study we identified afatinib and crizotinib in combination as a novel potential therapy for CMM independent of BRAF/NRAS mutation status. Herein, we elucidate the underlying mechanisms of the combination treatment effect to find biomarkers and novel targets for development of therapy that may provide clinical benefit by proteomic analysis of CMM cell lines and xenografts using mass spectrometry based analysis and reverse phase protein array. Identified candidates were validated using immunoblotting or immunofluorescence. Our analysis revealed that mTOR/Insulin signaling pathways were significantly decreased by the afatinib and crizotinib combination treatment. Both in vitro and in vivo analyses showed that the combination treatment downregulated pRPS6KB1 and pRPS6, downstream of mTOR signaling, and IRS-1 in the insulin signaling pathway, specifically ablating IRS-1 nuclear signal. Silencing of RPS6 and IRS-1 alone had a similar effect on cell death, which was further induced when IRS-1 and RPS6 were concomitantly silenced in the CMM cell lines. Silencing of IRS-1 and RPS6 resulted in reduced sensitivity towards combination treatment. Additionally, we found that IRS-1 and RPS6KB1 expression levels were increased in advanced stages of CMM clinical samples. We could demonstrate that induced resistance towards combination treatment was reversible by a drug holiday. CD171/L1CAM, mTOR and PI3K-p85 were induced in the combination resistant cells whereas AXL and EPHA2, previously identified mediators of resistance to MAPK inhibitor therapy in CMM were downregulated. We also found that CD171/L1CAM and mTOR were increased at progression in tumor biopsies from two matched cases of patients receiving targeted therapy with BRAFi. Overall, these findings provide insights into the molecular mechanisms behind the afatinib and crizotinib combination treatment effect and leverages a platform for discovering novel biomarkers and therapy regimes for CMM treatment.
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| 4. |
- Falkenius, Johan, et al.
(author)
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High expression of glycolytic and pigment proteins is associated with worse clinical outcome in stage III melanoma
- 2013
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In: Melanoma research. - 0960-8931 .- 1473-5636. ; 23:6, s. 452-460
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Journal article (peer-reviewed)abstract
- There are insufficient numbers of prognostic factors available for prediction of clinical outcome in patients with stage III malignant cutaneous melanoma, even when known adverse pathological risk factors, such as macrometastasis, number of lymph node metastases, and ulceration are taken into consideration. The aim of this study was therefore to identify additional prognostic factors to better predict patients with a high risk of relapse, thus enabling us to better determine the need for adjuvant treatment in stage III disease. An RNA oligonucleotide microarray study was performed on first regional lymph node metastases in 42 patients with stage III melanoma: 23 patients with short-term survival (13 months) and 19 with long-term survival (60 months), to identify genes associated with clinical outcome. Candidate genes were validated by real-time PCR and immunohistochemical analysis. Several gene ontology (GO) categories were highly significantly differentially expressed including glycolysis (GO: 0006096; P<0.001) and the pigment biosynthetic process (GO: 0046148; P<0.001), in which overexpression was associated with short-disease-specific survival. Three overexpressed glycolytic genes, GAPDHS, GAPDH, and PKM2, and two pigment-related genes, TYRP1 and OCA2, were selected for validation. A significant difference in GAPDHS protein expression between short- and long-term survivors (P=0.021) and a trend for PKM2 (P=0.093) was observed in univariate analysis. Positive expression of at least two of four proteins (GAPDHS, GAPDH, PKM2, TYRP1) in immunohistochemical analysis was found to be an independent adverse prognostic factor for disease-specific survival (P=0.011). Our results indicate that this prognostic panel in combination with established risk factors may contribute to an improved prediction of patients with a high risk of relapse.
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| 5. |
- Helgadottir, Hildur, et al.
(author)
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Cancer risks and survival in patients with multiple primary melanomas : Association with family history of melanoma and germline CDKN2A mutation status
- 2017
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In: Journal of the American Academy of Dermatology. - : Elsevier BV. - 0190-9622 .- 1097-6787. ; 77:5, s. 893-901
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Journal article (peer-reviewed)abstract
- Background Worse outcomes have been noted in patients with multiple primary melanomas (MPMs) than in patients with single primary melanomas. Objective We investigated how family history of melanoma and germline CDKN2A mutation status of MPM patients affects risks of developing subsequent melanomas and other cancers and survival outcomes. Methods Comprehensive data on cancer diagnoses and deaths of MPM patients, their first-degree relatives, and matched controls were obtained through Swedish national health care and population registries. Results Familial MPM cases with germline CDKN2A mutations were youngest at the diagnosis of their second melanoma (median age 42 years) and had among the MPM cohorts the highest relative risks (RR) compared to controls of developing >2 melanomas (RR 238.4, 95% CI 74.8-759.9). CDKN2A mutated MPM cases and their first-degree relatives were the only cohorts with increased risks of nonskin cancers compared to controls (RR 3.6, 95% CI 1.9-147.1 and RR 3.2, 95% CI 1.9-5.6, respectively). In addition, CDKN2A mutated MPM cases had worse survival compared with both cases with familial (HR 3.0, 95% CI 1.3-8.1) and sporadic wild-type MPM (HR 2.63, 95% CI 1.3-5.4). Limitations Our study examined outcomes in subgroups of MPM patients, which affected the sample size of the study groups. Conclusion This study demonstrates that CDKN2A mutation status and family history of melanoma significantly affects outcomes of MPM patients.
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| 6. |
- Helgadottir, Hildur, et al.
(author)
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CDKN2a mutation-negative melanoma families have increased risk exclusively for skin cancers but not for other malignancies.
- 2015
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In: International Journal of Cancer. - : Wiley. - 0020-7136 .- 1097-0215. ; 137:9, s. 2220-2226
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Journal article (peer-reviewed)abstract
- Germline CDKN2A mutations are found in 5-20% of melanoma families. Numerous studies have shown that carriers of CDKN2A mutations have increased risks of non-melanoma cancers, but so far there have been no studies investigating cancer risks in CDKN2A wild type (wt) melanoma families. In this prospective cohort study, index melanoma cases (n = 224) and their first-degree relatives (n = 944) were identified from 154 confirmed CDKN2A wt melanoma families. Cancer diagnoses in family members and matched controls were obtained from the Swedish Cancer Registry. Relative risks (RR), odds ratios (OR) and two-sided 95% confidence intervals (95% CI) were calculated. In index cases and first-degree relatives, the prospective RR for melanoma was 56.9 (95% CI 31.4-102.1) and 7.0 (95% CI 4.2-11.4), respectively, and for squamous cell skin cancers 9.1 (95% CI 6.0-13.7) and 3.4 (95% CI 2.2-5.2), respectively. In neither group, elevated risks were seen for non-skin cancers. In a subgroup analysis, CDKN2A wt melanoma families with young (<40 years) melanoma cases were found to have increased risk of non-skin cancers (RR 1.5, 95% CI 1.0-1.5). Further, MC1R gene variants were increased in familial melanoma cases compared to controls (OR 2.4, 95% CI 1.6-3.4). Our findings suggest that in the majority of CDKN2A wt melanoma families, a segregation of variants in low-risk melanoma genes such as MC1R causes increased skin cancer susceptibility, rather than mutations in high-risk cancer predisposing genes, such mutations are more probable to be found in melanoma families with young melanoma cases. This study further supports an implication of CDKN2A mutation screening as a clinical test that determines counseling and follows up routines of melanoma families.
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| 7. |
- Helgadottir, Hildur, et al.
(author)
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Germline CDKN2A Mutation Status and Survival in Familial Melanoma Cases
- 2016
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In: Journal of the National Cancer Institute. - : Oxford University Press (OUP). - 1460-2105 .- 0027-8874. ; 108:11
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Journal article (peer-reviewed)abstract
- BACKGROUND: Germline mutations in CDKN2A have been associated with increased risk of melanoma and tobacco-related cancers in respiratory and upper digestive tissues. In CDKN2A wild-type (wt) melanoma families, other known high-risk, melanoma-predisposing mutations are rare, and no increased risk has been observed for nonskin cancers in this group. This study is the first to compare survival in germline CDKN2A mutated (mut) and nonmutated melanoma cases.METHODS: Melanoma-prone families participating in this study were identified through a nationwide predictive program starting in 1987. Information on cancer diagnoses (types, stages, and dates) and deaths (causes and dates) were obtained through the Swedish Cancer Registry and Cause of Death Registry. Kaplan Meier and Cox proportional hazards regression models were used to assess survival in CDKN2A(mut) (n = 96) and CDKN2A(wt) (n = 377) familial melanoma cases and in matched sporadic melanoma cases (n = 1042). All statistical tests were two-sided.RESULTS: When comparing CDKN2A(mut) and CDKN2A(wt) melanoma cases, after adjusting for age, sex, and T classification, CDKN2A(mut) had worse survival than melanoma (hazard ratio [HR] = 2.50, 95% confidence interval [CI] = 1.49 to 4.21) and than nonmelanoma cancers (HR = 7.77, 95% CI = 3.65 to 16.51). Compared with matched sporadic cases, CDKN2A(mut) cases had statistically significantly worse survival from both melanoma and nonmelanoma cancers while no differences in survival were seen in CDKN2A(wt) compared with sporadic cases.CONCLUSIONS: CDKN2A(mut) cases had statistically significantly worse survival than nonmelanoma cancers and, intriguingly, also from melanoma, compared with melanoma cases with no CDKN2A mutations. Further studies are required to elucidate possible mechanisms behind increased carcinogen susceptibility and the more aggressive melanoma phenotype in CDKN2A mutation carriers.
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| 8. |
- Helgadottir, Hildur, et al.
(author)
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High risk of tobacco-related cancers in CDKN2A mutation-positive melanoma families.
- 2014
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In: Journal of Medical Genetics. - : BMJ. - 0022-2593 .- 1468-6244. ; 51:8, s. 545-552
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Journal article (peer-reviewed)abstract
- Germline mutations in the tumour suppressor gene CDKN2A occur in 5-20% of familial melanoma cases. A single founder mutation, p.Arg112dup, accounts for the majority of CDKN2A mutations in Swedish carriers. In a national program, carriers of p.Arg112dup mutation have been identified. The aim of this study was to assess cancer risks in p.Arg112dup carriers and their first degree relatives (FDRs) and second degree relatives (SDRs).
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| 9. |
- Hoiom, Veronica, et al.
(author)
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MC1R variation and melanoma risk in the Swedish population in relation to clinical and pathological parameters
- 2009
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In: Pigment Cell & Melanoma Research. - 1755-148X .- 1755-1471. ; 22:2, s. 196-204
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Journal article (peer-reviewed)abstract
- The genetic background of cutaneous malignant melanoma (CMM) includes both germ line aberrations in high-penetrance genes, like CDKN2A, and allelic variation in low-penetrance genes like the melanocortin-1 receptor gene, MC1R. Red-hair colour associated MC1R alleles (RHC) have been associated with red hair, fair skin and risk of CMM. We investigated MC1R and CDKN2A variation in relation to phenotype, clinical factors and CMM risk in the Swedish population. The study cohort consisted of sporadic primary melanoma patients, familial melanoma patients and a control group. An allele-dose dependent increase in melanoma risk for carriers of variant MC1R alleles (after adjusting for phenotype), with an elevated risk among familial CMM patients, was observed. This elevated risk was found to be significantly associated with an increased frequency of dysplastic nevi (DN) among familial patients compared to sporadic patients. MC1R variation was found to be less frequent among acral lentiginous melanomas (ALM) and dependent on tumour localisation. No association was found between CDKN2A gene variants and general melanoma risk. Two new variants in the POMC gene were identified in red haired individuals without RHC alleles.
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| 10. |
- Höiom, Veronica, et al.
(author)
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Hereditary uveal melanoma : A report of a germline mutation in BAP1
- 2013
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In: Genes, Chromosomes and Cancer. - : Wiley. - 1045-2257 .- 1098-2264. ; 52:4, s. 378-384
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Journal article (peer-reviewed)abstract
- Melanoma of the eye is a rare and distinct subtype of melanoma, which only rarely are familial. However, cases of uveal melanoma (UM) have been found in families with mixed cancer syndromes. Here, we describe a comprehensive search for inherited genetic variation in a family with multiple cases of UM but no aggregation of other cancer diagnoses. The proband is a woman diagnosed with UM at 16 years who within 6 months developed liver metastases. We also identified two older paternal relatives of the proband who had died from UM. We performed exome sequencing of germline DNA from members of the affected family. Exome-wide analysis identified a novel loss-of-function mutation in the BAP1 gene, previously suggested as a tumor suppressor. The mutation segregated with the UM phenotype in this family, and we detected a loss of the wild-type allele in the UM tumor of the proband, strongly supporting a causative association with UM. Screening of BAP1 germline mutations in families predisposed for UM may be used to identify individuals at increased risk of disease. Such individuals may then be enrolled in preventive programs and regular screenings to facilitate early detection and thereby improve prognosis.
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| 11. |
- Iles, Mark M., et al.
(author)
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A variant in FTO shows association with melanoma risk not due to BMI
- 2013
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In: Nature Genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 45:4, s. 428-432
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Journal article (peer-reviewed)abstract
- We report the results of an association study of melanoma that is based on the genome-wide imputation of the genotypes of 1,353 cases and 3,566 controls of European origin conducted by the GenoMEL consortium. This revealed an association between several SNPs in intron 8 of the FTO gene, including rs16953002, which replicated using 12,313 cases and 55,667 controls of European ancestry from Europe, the USA and Australia (combined P = 3.6 x 10(-12), per-allele odds ratio for allele A = 1.16). In addition to identifying a new melanomasusceptibility locus, this is to our knowledge the first study to identify and replicate an association with SNPs in FTO not related to body mass index (BMI). These SNPs are not in intron 1 (the BMI-related region) and exhibit no association with BMI. This suggests FTO's function may be broader than the existing paradigm that FTO variants influence multiple traits only through their associations with BMI and obesity.
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| 12. |
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| 13. |
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| 14. |
- Tuominen, Rainer
(author)
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Genetic and epigenetic alterations in melanoma
- 2015
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Doctoral thesis (other academic/artistic)abstract
- Malignant melanoma is a disease that may arise in several different parts of the body, preferentially the skin, rarely in the mucosal membranes or the choroidal tissues of the eye. The incidence of cutaneous melanoma (CMM) is steadily increasing in the Caucasian populations, unlike uveal melanoma (UM) that shows a stable incidence. The increase is likely to be related to t UV-irradiation leading to genetic aberrations that allow skin melanocytes to develop unlimited growth and immortality and ultimately lead to metastases. Paper I presents a genomic and epigenomic screening of 77 metastatic cutaneous melanoma metastases for the protein expression of p16INK4A in relation to 3 well-known causes of expression loss: truncating and non-synonymous mutations in CDKN2A, the gene for p16INK4A, transcriptional silencing of p16INK4A gene promoter and previously studied deletions in the CDKN2A loci encompassing p16INK4A. These aberrations were compared to p16INK4A expression in tumours and presence of mutations in BRAF and NRAS genes. Unexpectedly, a significant association between tumours carrying NRAS mutations and transcriptional silencing of p16INK4A promoter was observed. Paper II was a case study of a family with multiple cases of uveal melanoma. Family members with were found to be negative for germ-line CDKN2A aberrations, why next generation sequencing was employed. The proband, the proband’s sister and both parents were analyzed. The final mapped and filtered variants were filtered against variants found in the DNA of the non-carrier mother. A germ-line, frame-shift, insertion in BAP1 (exon 3 c.75insG) was identified and validated by Sanger sequencing. The insertion leads to a truncation at codon 43 and was found to segregate with the disease. Paper III is a retrospective study to evaluate the naturally occurring transcriptional silencing of DNA repair protein O6-methylguanine DNA methyltransferase, MGMT. MGMT activity counteracts the efficacy of alkylating chemotherapy. Two cohorts of patients mainly derived from Sweden (n=74) and Belgium (n=79) were included, in total encompassing 191 tumours. The hypermethylation of MGMT gene promoter was found in 21.5% of tumours successfully analyzed (28 positive, 130 total) and to be associated with a significantly longer progression free survival (PFS) and to be an independent variable in a multivariate analysis for PFS. Paper IV is an in vitro melanoma study for combination therapy efficacy. The BRAFV600E- melanoma cell line A375 and a mutant BRAF inhibitor (BRAFi)-resistant subline were subjected to sequential and simultaneous exposures for BRAFi PLX4720 and temozolomide (TMZ). Administration order was found to influence the treatment outcome: administration of BRAFi followed by TMZ displayed a poorer efficacy compared to exposure simultaneously or administration in the reverse order. This effect was related to BRAFi induction of MGMT mRNA and protein, but also induction of the DNA damage marker H2AX by BRAFi and TMZ.
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| 15. |
- Tuominen, Rainer, et al.
(author)
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Investigation of a putative melanoma susceptibility locus at chromosome 3q29
- 2014
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In: Cancer Genetics. - : Elsevier. - 2210-7762 .- 2210-7770. ; 207:3, s. 70-74
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Journal article (peer-reviewed)abstract
- Malignant melanoma, the most fatal form of skin cancer, is currently increasing in incidence in many populations. Approximately 10% of all cases occur in families with an inherited predisposition for melanoma. In Sweden, only a minor portion of such melanoma families carry a mutation in the known melanoma gene CDKN2A, and there is a need to identify additional melanoma susceptibility genes. In a recently performed genome-wide linkage screen, novel loci with suggestive evidence of linkage to melanoma were detected. In this study, we have further analyzed one region on chromosome 3q29. In all, 89 affected and 15 nonaffected family members from 42 melanoma-prone families were genotyped for 34 genetic markers. In a pooled linkage analysis of all 42 families, we detected significant evidence of linkage, with a maximum heterogeneity logarithm of odds (HLOD) score of 3.1 with 83% of the families contributing to the linkage score. The minimum critical region of linkage (defined by a 1LOD score support interval) maps to chromosome 3q29, spans 3.5 Mb of genomic sequence, and harbors 44 identified genes. Sequence variants within this region have previously been associated with cancer susceptibility. This study reports the presence of a putative novel melanoma susceptibility locus in the Swedish population, a finding that needs to be replicated in an independent study on other individuals with familial melanoma. Sequencing of genes in the region may identify novel melanoma-associated mutations.
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| 16. |
- Tuominen, Rainer, et al.
(author)
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The Role of Germline Alterations in the DNA Damage Response Genes BRIP1 and BRCA2 in Melanoma Susceptibility
- 2016
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In: Genes, Chromosomes and Cancer. - : Wiley-Blackwell. - 1045-2257 .- 1098-2264. ; 55:7, s. 601-611
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Journal article (peer-reviewed)abstract
- We applied a targeted sequencing approach to identify germline mutations conferring a moderately to highly increased risk of cutaneous and uveal melanoma. Ninety-two high-risk melanoma patients were screened for inherited variation in 120 melanoma candidate genes. Observed gene variants were filtered based on frequency in reference populations, cosegregation with melanoma in families and predicted functional effect. Several novel or rare genetic variants in genes involved in DNA damage response, cell-cycle regulation and transcriptional control were identified in melanoma patients. Among identified genetic alterations was an extremely rare variant (minor allele frequency of 0.00008) in the BRIP1 gene that was found to cosegregate with the melanoma phenotype. We also found a rare nonsense variant in the BRCA2 gene (rs11571833), previously associated with cancer susceptibility but not with melanoma, which showed weak association with melanoma susceptibility in the Swedish population. Our results add to the growing knowledge about genetic factors associated with melanoma susceptibility and also emphasize the role of DNA damage response as an important factor in melanoma etiology.
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| 17. |
- Vidarsdottir, Linda, et al.
(author)
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PTENP1-AS contributes to BRAF inhibitor resistance and is associated with adverse clinical outcome in stage III melanoma
- 2021
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In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 11:1
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Journal article (peer-reviewed)abstract
- BRAF inhibitors (BRAFi) selectively target oncogenic BRAFV600E/K and are effective in 80% of advanced cutaneous malignant melanoma cases carrying the V600 mutation. However, the development of drug resistance limits their clinical efficacy. Better characterization of the underlying molecular processes is needed to further improve treatments. We previously demonstrated that transcription of PTEN is negatively regulated by the PTEN pseudogene antisense RNA, PTENP1-AS, and here we investigated the impact of this transcript on clinical outcome and BRAFi resistance in melanoma. We observed that increased expression levels of PTENP1-AS in BRAFi resistant cells associated with enrichment of EZH2 and H3K27me3 at the PTEN promoter, consequently reducing the expression levels of PTEN. Further, we showed that targeting of the PTENP1-AS transcript sensitized resistant cells to BRAFi treatment and that high expression of PTENP1-AS in stage III melanoma correlated with poor survival. Collectively, the data presented here show that PTENP1-AS is a promising target for re-sensitizing cells to BRAFi and also a possible prognostic marker for clinical outcome in stage III melanoma.
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| 18. |
- Yang, Muyi, et al.
(author)
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Novel loss-of-function variant in DENND5A impedes melanosomal cargo transport and predisposes to familial cutaneous melanoma
- 2022
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In: Genetics in Medicine. - : Elsevier BV. - 1098-3600 .- 1530-0366. ; 24:1, s. 157-169
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Journal article (peer-reviewed)abstract
- Purpose: More than half of the familial cutaneous melanomas have unknown genetic predisposition. This study aims at characterizing a novel melanoma susceptibility gene. Methods: We performed exome and targeted sequencing in melanoma-prone families without any known melanoma susceptibility genes. We analyzed the expression of candidate gene DENND5A in melanoma samples in relation to pigmentation and UV signature. Functional studies were carried out using microscopic approaches and zebrafish model. Results: We identified a novel DENND5A truncating variant that segregated with melanoma in a Swedish family and 2 additional rare DENND5A variants, 1 of which segregated with the disease in an American family. We found that DENND5A is significantly enriched in pigmented melanoma tissue. Our functional studies show that loss of DENND5A function leads to decrease in melanin content in vitro and pigmentation defects in vivo. Mechanistically, harboring the truncating variant or being suppressed leads to DENND5A losing its interaction with SNX1 and its ability to transport the SNX1-associated vesicles from melanosomes. Consequently, untethered SNX1-premelanosome protein and redundant tyrosinase are redirected to lysosomal degradation by default, causing decrease in melanin content. Conclusion: Our findings provide evidence of a physiological role of DENND5A in the skin context and link its variants to melanoma susceptibility.
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| 19. |
- Yang, Xiaohong R., et al.
(author)
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Multiple rare variants in high-risk pancreatic cancer-related genes may increase risk for pancreatic cancer in a subset of patients with and without germline CDKN2A mutations
- 2016
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In: Human Genetics. - : Springer Science and Business Media LLC. - 0340-6717 .- 1432-1203. ; 135:11, s. 1241-1249
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Journal article (peer-reviewed)abstract
- The risk of pancreatic cancer (PC) is increased in melanoma-prone families but the causal relationship between germline CDKN2A mutations and PC risk is uncertain, suggesting the existence of non-CDKN2A factors. One genetic possibility involves patients having mutations in multiple high-risk PC-related genes; however, no systematic examination has yet been conducted. We used next-generation sequencing data to examine 24 putative PC-related genes in 43 PC patients with and 23 PC patients without germline CDKN2A mutations and 1001 controls. For each gene and the four pathways in which they occurred, we tested whether PC patients (overall or CDKN2A+ and CDKN2A− cases separately) had an increased number of rare nonsynonymous variants. Overall, we identified 35 missense variants in PC patients, 14 in CDKN2A+ and 21 in CDKN2A− PC cases. We found nominally significant associations for mismatch repair genes (MLH1, MSH2, MSH6, PMS2) in all PC patients and for ATM, CPA1, and PMS2 in CDKN2A− PC patients. Further, nine CDKN2A+ and four CDKN2A− PC patients had rare potentially deleterious variants in multiple PC-related genes. Loss-of-function variants were only observed in CDKN2A− PC patients, with ATM having the most pathogenic variants. Also, ATM variants (n = 5) were only observed in CDKN2A− PC patients with a family history that included digestive system tumors. Our results suggest that a subset of PC patients may have increased risk because of germline mutations in multiple PC-related genes.
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