[Show abstract][Hide abstract] ABSTRACT: PURPOSE: Gastrointestinal stromal tumors (GISTs) are mesenchymal tumors of the gastrointestinal tract. Most (80 %) contain activating mutations in the KIT receptor tyrosine kinase, roughly 10 % in platelet-derived growth factor receptor-alpha (PDGFRA). In a small subset, BRAF mutations are an alternative molecular pathway. GISTs respond well to imatinib, but low response is seen in patients with wild-type KIT or PDGFRA. Resistance has also been reported as a result of mutations in downstream effectors such as BRAF. METHODS: We provide here a molecular characterization of a series of primary GISTs from Italian patients. Of 121 GIST cases diagnosed between 2000 and 2012, 83 were evaluated by PCR amplification and direct sequencing for mutations in KIT exons 8, 9, 11, 13, and 17, PDGFRA exons 12, 14, and 18, and BRAF exon 15. Eighty-one GISTs also underwent K-RAS testing. RESULTS: Sixty-four GISTs were positive: 55 had mutations in KIT and 9 in PDGFRA; 16 patients were mutation negative. Three samples came from NF1 patients and were KIT- and PDGFRA negative. Overall, we identified six novel mutations in KIT (p.K550_M552delinsL, p.Q556_W557delinsG p.Q556_G575del, p.W557_V559delinsQ p.P573_R588dup, p.G592_K593dup) and one novel mutation in PDGFRA (p.D842_N848delinsVDV), thus contributing to widening the spectrum of known mutations in GIST tumors and confirming the most frequently altered regions underlying GIST development. CONCLUSIONS: Among the 64 KIT- and PDGFRA-positive sporadic patients in our series, no BRAF or KRAS mutations were identified, suggesting that co-occurrence of these mutations is likely to be rare in the northwestern Italian population and not a frequent cause of primary resistance to imatinib in KIT-positive GIST patients.
[Show abstract][Hide abstract] ABSTRACT: Pancreatic adenocarcinoma (PC) is the third most common cancer associated with BRCA mutations. Most notice has been given to BRCA2, while the association between BRCA1 and PC is less widely reported. Recently, PALB2 has been implicated in both PC and breast cancer (BC) susceptibility. We selected 29 Italian PC patients from a case-control study of PC according to their personal and family history of both PC and breast/ovarian cancer (BC/OC) and tested them for presence of germline mutations in BRCA1, BRCA2 and PALB2. We identified no germline mutations or deletions in PALB2, but detected 7 BRCA mutations (4 in BRCA1 and 3 in BRCA2). These findings suggest that PALB2 does not play a major role in PC susceptibility in our population. As we found an almost equal frequency of germline mutations in BRCA1 and BRCA2, germline alterations in either of these genes may explain a subset of Italian families presenting both PC and BC/OC. Moreover, as we began the observation of these families from probands who are affected by PC, we provide here a direct assessment of the role of PALB2 and BRCA mutations in PC susceptibility.
Familial Cancer 03/2012; 11(1):41-7. · 1.94 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Background Most familial pancreatic cancer (FPC) remains unexplained. The identification of individuals with a high genetic risk of developing pancreatic adenocarcinoma (PC) is important to elucidate its biological basis and is critical to better define emerging strategies for the detection of early pancreatic neoplasms. Patients and methods A series of 225 consecutively enrolled patients with PC were tested for CDKN2A mutations. After personal and family cancer histories of all the patients had been reviewed, a subset of the patients were classified as FPC and were also tested for mutations in PALLD, PALB2, BRCA1 and BRCA2 as FPC candidate genes. Results The CDKN2A mutation rate in the 225 PC cases was 5.7%. The CDKN2A founder mutations, p.E27X and p.G101W, were predominant, but the mutation spectrum also included p.L65P, p.G67R and two novel, potentially pathogenic variants, promoter variant c.-201ACTC>CTTT and p.R144C. None of the patients with FPC harboured germline mutations in PALLD, PALB2 or BRCA2. One family was positive for the BRCA1 UV variant p.P727L. Strikingly, five of 16 patients with FPC (31%) carried CDKN2A mutations. Conclusion These findings suggest that a sizeable subset of Italian FPC families may carry CDKN2A mutations. This result may be of value for identifying the best candidates for future PC screening trials in Italy.
Journal of Medical Genetics 03/2012; 49(3):164-70. · 5.70 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Germline CDKN2A mutations are observed in 20-50% of melanoma-prone families. We identified melanoma patients that were heterozygous for non-coding germline variants in the 5'-UTR of CDKN2A (c.-21C > T; c.-25C > T&c.-180G > A; c.-56G > T; c.-67G > C) and examined their impact on the p16(INK4a) 5'-UTR activity using two luciferase-based reporter vectors that differ in basal transcription level and that were transfected into the melanoma-derived WM266-4 and in the breast cancer-derived MCF7 cells. The wild-type 5'-UTR sequence, containing a reported SNP (c.-33G > C) and a known melanoma-predisposing mutation (c.-34G > T), was included as controls. Results revealed that the variants at -21 and -34 severely reduced the reporter activity. The variants at -56 and at -25&-180 exhibited a milder impact, while results with c.-67G > C were dependent on the plasmid type. Quantification of the luciferase mRNA indicated that the effects of the variants were mainly post-transcriptional. Using a bicistronic dual-luciferase reporter plasmid, we confirmed that c.-21C > T and c.-34G > T had a severe negative impact in both cell lines. We also applied a polysomal profiling technique to samples heterozygous for the 5'-UTR variants, including patient-derived lymphoblasts. Analysis of allelic imbalance indicated that in addition to the c.-21C > T variant, the c.-56T > G and c.-67G > C variants also reduced mRNA translation efficiency. Overall, our results suggest that the c.-21C > T sequence variant is a melanoma-predisposing mutation. The c.-25C > T&c.-180G > A and particularly the c.-56G > T variants showed a range of intermediate functional defects in the different assays, and were not observed in the control population. We propose that these variants should be considered as potential mutations.
Human Molecular Genetics 04/2010; 19(8):1479-91. · 7.69 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Lynch syndrome is an inherited cancer syndrome caused by germline mutations in mismatch repair (MMR) genes MLH1, MSH2, MSH6 and PMS2. LS predisposes to high risk of early-onset colorectal, endometrial and other tumors. Patients with Lynch syndrome have also been shown to have an elevated risk for pancreatic cancer (PC). In this study, we aimed to estimate the frequency of suspected Lynch syndrome among a series of 135 PC patients. Further, we wanted to determine the frequency of MMR gene mutations in the suspected Lynch syndrome cases. We also aimed to verify the pathogenicity of any novel non-truncating variants we might detect with a functional assay. Based on personal and/or familial cancer history, 19 patients were classified as suspected Lynch syndrome cases. DNA material for mutation analysis was available for eleven of them. Four patients were found to carry a total of five MLH1 or MSH2 variants. Of these, MSH2-Q402X, MSH2-G322D, and MLH1-K618A had been previously reported, while the MSH2-E205Q and MSH2-V367I variants were novel. MSH2-Q402X is a known stop mutation and reported here for the first time here in association with PC. MLH1-K618A was found in the unaffected branch of a kindred, suggesting that it may be a polymorphism or a low penetrance variant. MSH2-G322D likely does not cause a MMR defect, although this variant has also been associated with breast cancer as indeed seen in our patient. The novel variants MSH2-E205Q and MSH2-V367I were found in the same patient. Both novel variants were however functional in the applied MMR assay. Our findings suggest that only a small subset of pancreatic cancer patients carry pathogenic MMR mutations.
Familial Cancer 10/2009; 8(4):547-53. · 1.94 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The Italian Society of Human Genetics' (SIGU) recommendations on genetic counseling and testing for hereditary melanoma state that clinical genetic testing can be offered to Italian melanoma families with at least two affected members.
In the framework of a cooperative study, we sought to establish the frequency of cyclin-dependent kinase inhibitor 2A mutations in melanoma families that underwent clinical genetic counseling and testing in accordance with the SIGU recommendations at 9 centers in different Italian regions.
Cyclin-dependent kinase inhibitor 2A testing was conducted by direct sequencing and multiplex ligation-dependent probe amplification analysis in melanoma families with at least two affected members.
A total of 33% (68/204) of the families harbored cyclin-dependent kinase inhibitor 2A mutations. In the 145 families with two affected members the mutation frequency was 25%. Three novel mutations, L94P, A86T, and c.407dupG, were identified among the cases and not in 200 controls.
We were unable to perform separate analyses for individual centers, as in some cases the number of families was too small.
The availability of clinical genetic testing for melanoma to families with just two affected members in the same branch is justified in Italy in terms of the likelihood of identifying a mutation.
Journal of the American Academy of Dermatology 07/2009; 61(5):775-82. · 4.91 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Amelanotic melanoma (AM) is a rare subtype of melanoma with little or no clinically visible pigment; it is more difficult to diagnose than pigmented melanoma (PM), and has a worse prognosis. In the attempt to find a genetic explanation for the distinction between AM and PM, we conducted a case-case study, matching AM and PM patients, and testing them for germline mutations in high- (p16INK4A, p14ARF, CDK4) and low-penetrance (MC1R) melanoma susceptibility genes. Similar CDKN2A mutations were found in both sets of melanomas. A p14ARF splice germline mutation was detected for the first time in an Italian family with AM. This rare mutation, which has been described only once previously, may be involved in predisposition to the amelanotic phenotype in combination with germline MC1R variants and coordinate somatic expression of pigmentation genes and their regulators.
Melanoma research 04/2009; 19(3):142-5. · 2.06 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We evaluated the contribution of germline CDKN2A mutations and MC1R variants to the development of melanoma in a hospital-based study of single (SPM, n = 398) and multiple primary melanoma (MPM, n = 95). The overall frequency of CDKN2A mutations was 15.2%, and four-fold higher in MPM than in SPM cases (OR = 4.27; 95% CI 2.43-7.53). The likelihood of identifying a CDKN2A mutation increased with family history of melanoma and younger age at diagnosis in MPM cases. Compared to SPM patients, the risk of harboring a CDKN2A mutation rose as the number of primary melanomas increased and was not influenced by family history. The G101W and E27X founder mutations were the most common. Several other mutations (W15X, Q50X, R58X, A68L, A127P and H142R) were detected for the first time in Italian patients. One novel mutation, T77A, was identified. Several non-coding variants with unknown functional significance were also found (5'UTR -25C > T, -21C > T, -67G > C, IVS1 +37G > C); the novel 5'UTR -21C > T variant was not detected in controls. The CDKN2A A148T polymorphism was more frequent in MPM patients than in the control population (15.7% versus 6.6%). Compared to the SPM patients, MPM cases had a 2-fold increased probability of being MC1R variant carriers and a higher probability of carrying two or more variants. No specific association was observed between the type of variant and the number of melanomas, suggesting that the number rather than the type of MC1R variant increases the risk of MPM. We observed no interaction between CDKN2A status and the presence of MC1R variants. The high frequency of CDKN2A mutations in our MPM cases, independent of their family history, is of relevance to genetic counseling and testing in our population.
[Show abstract][Hide abstract] ABSTRACT: Mutations in the CDKN2A gene underlie melanoma susceptibility in as many as 50% of melanoma kindreds in selected populations, and several CDKN2A founder mutations have been described. Inherited mutations in CDKN2A have been found to be associated with other, non-melanoma cancers including pancreatic cancer (PC) and neural system tumors (NST). Here we report a novel germline mutation in exon 1 of the CDKN2A gene, E27X, which we first detected in melanoma patients living in or originally from a small geographic area bordering Liguria in north-western Italy. A subset of melanoma kindreds positive for this mutation displayed PC and neuroblastoma. E27X generates a premature stop codon, leading to dramatically reduced protein levels of p16 and leaving p14ARF unaltered. As PC and NSTs have been postulated to be preferentially associated with CDKN2A mutations located in exon 2 and/or affecting p14ARF alone, the position of E27X in exon 1alpha provides interesting insights towards clarifying the mechanisms by which the CDKN2A/ARF locus is involved in cancer predisposition.
Human Molecular Genetics 10/2006; 15(18):2682-9. · 7.69 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Although the presence of multiple cases of melanoma on the same side of a family is the best predictor of germline CDKN2A mutation, other features (i.e. early age at onset) may be useful to identify carriers. We analysed the records of 682 hospital-based Ligurian melanoma patients. Of these, 238 cases (34 familial, 14 non-familial multiple primary and 190 non-familial single primary melanomas) were consecutively enrolled for screening of the CDKN2A and CDK4 genes. Screening of the 34 familial patients revealed that nine were carriers of the CDKN2A G101W founder mutation. Of the 14 non-familial multiple primary melanoma patients, three carried the G101W founder mutation and one the P48T mutation. For the non-familial patients with a single melanoma, 17 of 190 carried germline CDKN2A mutations, with most (16/17) carrying the G101W Ligurian founder mutation and one a novel single base pair substitution, D74Y. The effect of mutation on age at diagnosis was significant (P=0.012) after correcting for melanoma type (familial or non-familial), number of primaries (single or multiple), gender and disease occurrence (incident or prevalent). Early age at onset may be a good predictor of CDKN2A mutation in Liguria, where the G101W founder mutation is prevalent among melanoma patients, independent of family history.
Melanoma Research 01/2005; 14(6):443-8. · 2.52 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Expression of p16INK4A, the product of the melanoma susceptibility gene CDKN2A, has been shown to decrease in correlation with tumor progression. P16INK4A is a key regulator of cell-cycle function, and likely interacts with a variety of targets alongside cyclin-dependent kinases (CDKs). One such target is nuclear factor KB (NF-kappaB), a pleiotropic transcription factor that plays a crucial role in apoptosis, oncogenesis and cell cycle control. NF-kappaB p65 has been shown to be activated in melanoma cell lines but few studies decribe its expression in the tissue. In the present study we focused on synchronous expression of p16INK4A and NF-kappaB p65 and their functional activation in melanoma cell lines and biopsy tissue. Activation of NF-kappaB p65, as observed by electrophoretic mobility shift assay in cell lines, was correlated with expression and cellular localization of the active and inactive forms of its inhibitor, IkappaB-alpha. In melanocytic lesions, p16INK4A and NF-kappaB p65 expression were inversely correlated with levels of the nuclear component of NF-kappaB p65 increasing from nevi to primary melanomas and metastases.
Human Pathlogy 09/2004; 35(8):1029-37. · 2.84 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Expression of p16INK4A, the product of the melanoma susceptibility gene CDKN2A, has been shown to decrease in correlation with tumor progression. P16INK4A is a key regulator of cell-cycle function, and likely interacts with a variety of targets alongside cyclin-dependent kinases (CDKs). One such target is nuclear factor KB (NF-κB), a pleiotropic transcription factor that plays a crucial role in apoptosis, oncogenesis and cell cycle control. NF-κB p65 has been shown to be activated in melanoma cell lines but few studies decribe its expression in the tissue. In the present study we focused on synchronous expression of p16INK4A and NF-κB p65 and their functional activation in melanoma cell lines and biopsy tissue. Activation of NF-κB p65, as observed by electrophoretic mobility shift assay in cell lines, was correlated with expression and cellular localization of the active and inactive forms of its inhibitor, IκB-α. In melanocytic lesions, p16INK4A and NF-κB p65 expression were inversely correlated with levels of the nuclear component of NF-κB p65 increasing from nevi to primary melanomas and metastases.
Human Pathology - HUM PATHOL. 01/2004; 35(8):1029-1037.