Clinical impact of TP53 alterations in adrenocortical carcinomas.

BACKGROUND: To evaluate the role of somatic TP53 mutations and to correlate somatic and germline mutations with results of immunostaining, a large cohort of ACC patients was analyzed. PATIENTS AND METHODS: Patients with ACC who underwent potential curative surgery at the authors' department were screened for TP53 somatic and germline mutations in exons 5, 6, 7, 8, and 10 by DHPLC analysis. Aberrant samples were further analyzed by direct sequencing. Immunostaining was performed on corresponding paraffin sections in all patients. Complete clinical and follow-up data were correlated with the status of TP53. RESULTS: Thirty ACC patients were included. Four of 30 patients showed aberrant DHPLC configuration and direct sequencing confirmed 2 (7%) germline mutations (R337H, R248W), 1 (3%) somatic mutation (R213X), and 1 (3%) noncoding polymorphism (g.17708 A>T). The only patient with a positive family history harbored a TP53 mutation. Tumors of the three patients with mutations showed aberrant p53 expression in more than 10% of cells by immunostaining, compared to only 3 of 27 patients without mutations (p = 0.009). Aberrant p53 expression (>5%) was detected in 12/30 (40%) ACCs. The latter was associated with an increased Ki67 and van Slooten index (p ≤ 0.001; p = 0.020). Disease-free survival decreased significantly in patients with aberrant p53 IHC of more than 5% of cells (65.7 ± 12.4 vs. 26.6 ± 8.7 months; p = 0.043 log rank test). CONCLUSIONS: Patients with ACC revealed aberrant expression of p53 in 40%, and mutations were identified in 25% of these patients. Therefore aberrant p53 expression should be considered an indicator for genetic testing. A subgroup of apparently sporadic ACC is caused by TP53 germline mutations, and family history is a strong indicator for p53 germline mutations.

Frequent methylation-associated silencing of the tissue inhibitor of metalloproteinase-3 gene in pancreatic endocrine tumors.

Molecular mechanisms contributing to the tumorigenesis of pancreatic endocrine tumors (PETs) are still not well understood. Allelic deletions at chromosome 22q12.3 were detected in about 30-60% of PETs, suggesting that inactivation of one or more tumor suppressor genes on this chromosomal arm is important for their pathogenesis. Because the putative tumor suppressor gene tissue inhibitor of metalloproteinase-3 (TIMP-3) has been located at 22q12.3, we undertook a genetic analysis of TIMP-3 to determine its role in the tumorigenesis of PETs. Single-strand conformational polymorphism analysis, methylation-specific PCR, RNA expression analysis, and immunohistochemistry of TIMP-3 were performed in 21 sporadic PETs. Thirteen of 21 PETs (62%) revealed TIMP-3 alterations, including promoter hypermethylation and homozygous deletion. The predominant TIMP-3 alteration was promoter hypermethylation, identified in 8 of 18 (44%) PETs. It was tumor-specific and corresponded to loss or strong reduction of TIMP-3 protein expression. Notably, 11 of 14 (79%) PETs with metastases had TIMP-3 alterations, compared with only 1 of 7 (14%) PETs without metastases (P < 0.02). These data suggest a possibly important role of TIMP-3 in the tumorigenesis of human PETs, especially in the development of metastases, which has to be further evaluated in large-scale studies.

Chromosome 22q in pancreatic endocrine tumors: identification of a homozygous deletion and potential prognostic associations of allelic deletions.

OBJECTIVE: A variety of human tumors frequently show allelic deletions of chromosome 22q, suggesting that inactivation of one or more tumor suppressor genes in this region is important for their tumorigenesis. METHODS: In this study, 23 patients with pancreatic endocrine tumors (PETs), including gastrinomas, VIPomas and non-functioning islet cell carcinomas, were analyzed for loss of heterozygosity (LOH) on chromosome 22q with 12 microsatellite and 7 sequence tagged site markers. RESULTS: LOH on chromosome 22q was identified in 22 of 23 (96%) PETs. Markers in the chromosomal region 22q12.1 revealed LOH rates up to 85%. Notably, one tumor revealed a homozygous deletion in a second region at 22q12.3. LOH at this locus occurred more frequently in tumors with distant metastases (10 of 11) compared with tumors without distant metastases (3 of 12; P=0.0057) and, overall, allelic loss of 22q is positively correlated with distant metastases (r=0.78; P<0.0001). CONCLUSIONS: These findings are suggestive for novel tumor suppressor gene loci at chromosome 22q that might contribute to the pathogenesis of PETs, especially to the development of distant metastases.

Higher risk of aggressive pancreatic neuroendocrine tumors in MEN1 patients with MEN1 mutations affecting the CHES1 interacting MENIN domain.

CONTEXT: Sixty to 80% of multiple endocrine neoplasia type 1 (MEN1) patients develop pancreatic neuroendocrine neoplasias (pNENs), which reveal an aggressive behavior in 10%-20% of patients. Causative MEN1 mutations in the interacting domains of the encoded Menin protein directly alter its regulation abilities and may influence the phenotype. OBJECTIVE: The objective of the study was the evaluation of an association between MEN1 mutations in different interacting domains of Menin and the phenotype of pNENs. DESIGN: This was a retrospective analysis of a prospectively collected cohort of 71 genetically confirmed MEN1 patients at a tertiary referral center. MAIN OUTCOME MEASURES: Analysis of patients' characteristics and clinical phenotype of pNENs regarding the mutation type and its location in Menin interacting domains was measured. RESULTS: Sixty-seven patients (93%) developed pNENs after a median follow-up of 134 months. Patients with mutations leading to loss of interaction (LOI) with the checkpoint kinase 1 (CHES1) interacting domain codons (428-610) compared with patients with mutations resulting in LOI with other domains (eg, JunD, Smad3) had significantly higher rates of functioning pNENs (70% vs 34%), malignant pNENs (59% vs 16%), and aggressive pNENs (37% vs 9%), respectively. Patients with CHES1-LOI also had an increased pNEN-related mortality (20% vs 4.5%). Neither gender, age, nor the ABO blood types were associated with the phenotype of pNENs. CONCLUSIONS: MEN1 patients with MEN1 mutations leading to CHES1-LOI have a higher risk of malignant pNENs with an aggressive course of disease and disease-related death.

LCN2 and TIMP1 as Potential Serum Markers for the Early Detection of Familial Pancreatic Cancer.

High-risk individuals of familial pancreatic cancer (FPC) families are considered to be good candidates for screening programs to detect early PC or its high-grade precursor lesions, especially pancreatic intraepithelial neoplasia (PanIN) 2/3 lesions. There is a definite need for diagnostic markers as neither reliable imaging methods nor biomarkers are available to detect these lesions. On the basis of a literature search, the potential serum markers neutrophil gelatinase-associated lipocalin (LCN2), metallopeptidase inhibitor 1 (TIMP1), chemokine (C-X-C motif) ligand 16 (CXCL16), IGFBP4, and iC3a, which were first tested in transgenic KrasLSL.(G12D/+);p53(R172H/+);Pdx1-Cre mice, were identified. ELISA analyses of LCN2, TIMP1, and CXCL16 revealed significantly higher levels in mice with PanIN2/3 lesions or PC compared to mice with normal pancreata or PanIN1 lesions. Analysis of preoperative human serum samples from patients with sporadic PC (n = 61), hereditary PC (n = 24), chronic pancreatitis (n = 28), pancreatic neuroendocrine tumors (n = 11), and FPC patients with histologically proven multifocal PanIN2/3 lesions (n = 3), as well as healthy control subjects (n = 20), confirmed significantly higher serum levels of LCN2 and TIMP1 in patients with PC and multifocal PanIN2/3 lesions. The combination of LCN2 and TIMP1 as a diagnostic test for the detection of PC had a sensitivity, specificity, and positive predictive value of 100% each. Although this preliminary finding needs to be validated in a large series of individuals at high risk for FPC, serum measurement of LCN2 and TIMP1 might be a promising screening tool.

Prevalence of BRCA2 and CDKN2a mutations in German familial pancreatic cancer families.

Previous small scale studies reported that deleterious BRCA2 and CDKN2a germline mutations contribute to a subset of families with inherited pancreatic cancer. As the prevalence of those mutations in the setting of familial pancreatic cancer is still not well defined for the German population, we evaluated the presence of BRCA2 and CDKN2a germline mutations in a large cohort of familial pancreatic cancer (FPC) families from the German National Case Collection for Familial Pancreatic Cancer (FaPaCa). Fifty-six FPC families with at least two-first-degree relatives with confirmed pancreatic cancer that did not fulfill the criteria of other tumor predisposition syndromes, were analyzed for BRCA2 and CDKN2a germline mutations by DHPLC and/or direct sequencing. No deleterious CDKN2a mutations were identified in our families suggesting that CDKN2a mutations are unlikely to predispose PC in FPC families without melanoma. No deleterious BRCA2 mutations, but 6 unclassified variants, were detected in our FPC collection. Combining the prevalence of deleterious BRCA2 germline mutations from our previous separate study with the data from this study we were able to much more accurately estimate the BRCA2 carrier frequency for FPC families in the German population. A total of two mutations and 6 unclassified variants (mutation range: 2.8-11.4%) were thus identified in 70 German FPC families, indicating that the prevalence of BRCA2 mutations in the German FPC population is less frequent than previously reported.

Alterations of the tissue inhibitor of metalloproteinase-3 (TIMP3) gene in pancreatic adenocarcinomas.

OBJECTIVES: Tissue inhibitor of metalloproteinase-3 (TIMP3) antagonizes matrix metalloproteinase activity and can suppress tumor growth, angiogenesis, invasion, and metastases. In the present study, the involvement of TIMP3 in the tumorigenesis of 34 pancreatic adenocarcinomas was evaluated. METHODS: Immunohistochemistry, methylation-specific PCR, and RNA expression analysis (RT-PCR) of TIMP3 were performed in 34 resected and microdissected primary pancreatic adenocarcinomas. RESULTS: Immunohistochemistry showed loss or strongly reduced protein expression in 17 of 34 pancreatic adenocarcinomas (50%) that corresponded to loss of TIMP3-RNA-expression. Promoter hypermethylation was identified in 2 of 34 tumors (6%). It was tumor specific and corresponded to a loss of TIMP3 protein expression. TIMP3 alterations did not correlate with any clinical feature such as tumor size or survival. CONCLUSION: TIMP3 seems to play an important role in the tumorigenesis of primary pancreatic adenocarcinomas. In contrast to other tumors, hypermethylation seems not to be the key mechanism for the inactivation of TIMP3. Other methods of gene inactivation need to be identified.

RNASEL germline variants are associated with pancreatic cancer.

The RNASEL (encoding ribonuclease L) gene Glu265X mutation has been implicated in familial prostate cancer, and an association between the RNASEL Arg462Gln variant and sporadic and familial prostate cancer, has also been suggested. Because prostate cancer occurs in some familial pancreatic cancer families, we evaluated the role of the RNASEL gene variants Glu265X and Arg462Gln in the etiology of pancreatic cancer. Exon 2 of the RNASEL gene was directly sequenced in the germline of 36 familial and 75 sporadic pancreatic cancer patients and in 108 controls. The Glu265X mutation was identified in one (2.8%) familial and one (1.3%) sporadic pancreatic cancer case, but not in any of the controls. Arg462Gln variants were identified in 61 (56%) controls and in 55 (73%) sporadic pancreatic cancer cases with 8 (7%) and 12 (16%) homozygotes, respectively (p = 0.009). For homozygous carriers the increased risk for pancreatic cancer was 3.5 (odds ratio [OR] = 3.53, 95% confidence interval [CI] = 1.11-11.46, p = 0.03). The population attributable fraction (PAF) was 38.7% (95% CI = 0.08-0.80). In familial pancreatic cancer no association between Arg462Gln genotypes and pancreatic cancer risk was evident. In sporadic pancreatic cancer there were no significant differences between Arg462Gln genotypes regarding clinical characteristics. In familial pancreatic cancer, however, patients with Arg462Gln variants had more aggressive tumors with more high grade cancers (OR = 15.40, p = 0.009) and more distant metastases (OR = 7.00, p = 0.04) than patients with the wild-type genotype. Our results suggest that RNASEL variants Glu265X and Arg462Gln may contribute to the tumorigenesis of sporadic and familial pancreatic cancer, which has to be proven in large scale studies.