Increased incidence of pathogenic variants in ATM in the context of testing for breast and ovarian cancer predisposition.

Pathogenic Variants (PV) in major cancer predisposition genes are only identified in approximately 10% of patients with Hereditary Breast and Ovarian Cancer (HBOC) syndrome. Next Generation Sequencing (NGS) leads to the characterization of incidental variants in genes other than those known to be associated with HBOC syndrome. The aim of this study was to determine if such incidental PV were specific to a phenotype. The detection rates of HBOC-associated and incidental PV in 1812 patients who underwent genetic testing were compared with rates in control groups FLOSSIES and ExAC. The rates of incidental PV in the PALB2, ATM and CHEK2 genes were significantly increased in the HBOC group compared to controls with, respective odds ratios of 15.2 (95% CI = 5.6-47.6), 9.6 (95% CI = 4.8-19.6) and 2.7 (95% CI = 1.3-5.5). Unsupervised Hierarchical Clustering on Principle Components characterized 3 clusters: by HBOC (P = 0.01); by ExAC and FLOSSIES (P = 0.01 and 0.02 respectively); and by HBOC, ExAC and FLOSSIES (P = 0.01, 0.04 and 0.04 respectively). Interestingly, PALB2 and ATM were grouped in the same statistical cluster defined by the HBOC group, whereas CHEK2 was in a different cluster. We identified co-occurrences of PV in ATM and BRCA genes and confirmed the Manchester Scoring System as a reliable PV predictor tool for BRCA genes but not for ATM or PALB2. This study demonstrates that ATM PV, and to a lesser extent CHEK2 PV, are associated with HBOC syndrome. The co-occurrence of ATM PV with BRCA PV suggests that such ATM variants are not sufficient alone to induce cancer, supporting a multigenism hypothesis.

Clinical presentation of PTEN mutations in childhood in the absence of family history of Cowden syndrome.

BACKGROUND: PTEN gene (MIM 601628) is a tumor suppressor gene implicated in PTEN hamartoma tumor syndromes (PHTS) including Cowden syndrome, Bannayan-Riley-Ruvalcaba syndrome, and Proteus-like syndrome. Bannayan-Riley-Ruvalcaba syndrome is considered as the pediatric form of PHTS. More recently, children presenting autism spectrum disorders with macrocephaly (ASD-M) have been reported. METHODS: We report clinical data from seven patients diagnosed in childhood with a PTEN germline mutation, excluding cases of familial Cowden syndrome. RESULTS: This study underlines the variability of phenotype associated with PTEN mutations diagnosed at pediatric age. Most of the patients did not fulfill usual criteria of Bannayan-Riley-Ruvalcaba syndrome or ASD-M. CONCLUSION: PTEN testing should be considered in any child presenting with severe macrocephaly (>+4SD) and another feature of PHTS.

A refined molecular taxonomy of breast cancer.

The current histoclinical breast cancer classification is simple but imprecise. Several molecular classifications of breast cancers based on expression profiling have been proposed as alternatives. However, their reliability and clinical utility have been repeatedly questioned, notably because most of them were derived from relatively small initial patient populations. We analyzed the transcriptomes of 537 breast tumors using three unsupervised classification methods. A core subset of 355 tumors was assigned to six clusters by all three methods. These six subgroups overlapped with previously defined molecular classes of breast cancer, but also showed important differences, notably the absence of an ERBB2 subgroup and the division of the large luminal ER+ group into four subgroups, two of them being highly proliferative. Of the six subgroups, four were ER+/PR+/AR+, one was ER-/PR-/AR+ and one was triple negative (AR-/ER-/PR-). ERBB2-amplified tumors were split between the ER-/PR-/AR+ subgroup and the highly proliferative ER+ LumC subgroup. Importantly, each of these six molecular subgroups showed specific copy-number alterations. Gene expression changes were correlated to specific signaling pathways. Each of these six subgroups showed very significant differences in tumor grade, metastatic sites, relapse-free survival or response to chemotherapy. All these findings were validated on large external datasets including more than 3000 tumors. Our data thus indicate that these six molecular subgroups represent well-defined clinico-biological entities of breast cancer. Their identification should facilitate the detection of novel prognostic factors or therapeutical targets in breast cancer.

A critical analysis of treatment strategies in desmoid tumours: a review of a series of 106 cases.

BACKGROUND: The management of desmoid tumours, previously based on strategies employed for sarcomas, should be reassessed, given the morbidity of interventions used in their treatment. METHODS: Long-term follow-up (median 123 months) of a series of 106 treated patients with 69 primary and 37 recurrent desmoids, in order to study natural history and outcome. RESULTS: Desmoids typically evolved actively over a median period of 3 years, and stabilised thereafter. Recurrences or progression most commonly occurred between 14 and 17 months. Risk factors for recurrence were presentation (primary vs. recurrent), gender, tumour location and resection margins. However, survival was independent from these factors, with equivalent survival whether resection had been performed or not. Tumour control and functional outcome depended on location and presentation. Functional impairment was proportional to number of operations and whether patients had received radiotherapy. Recurrences were observed in 12/23 patients after radiotherapy. CONCLUSION: Desmoids are relatively indolent tumours needing different approaches than sarcomas. Direct surgery is advisable only in primary lower trunk wall/girdle locations. Wait-and-see and medical treatment is preferable in other types of presentations.

Contribution of PTEN large rearrangements in Cowden disease: a multiplex amplifiable probe hybridisation (MAPH) screening approach.

BACKGROUND: Cowden disease is an autosomal dominant syndrome predisposing to cancer and characterised by the occurrence throughout life of hyperplastic, hamartomatous and tumoural lesions affecting various organs. In 60-80% of patients a germline intragenic point mutation of the PTEN tumour suppressor gene is identified, but at least 20% of patients with a well characterised phenotype remain without any identified mutation. METHODS: To evaluate the impact of large rearrangement involving the PTEN locus in Cowden disease, we analysed by a multiplex amplifiable probe hybridisation (MAPH) technique 80 unrelated patients referred for diagnosed or suspected Cowden disease, and in whom no PTEN point mutation was detected by a denaturing gradient gel electrophoresis (DGGE) screening. RESULTS: Four heterozygous genomic deletions involving the PTEN gene were identified. These deletions ranged from 13.6-662 kb and are restricted to the PTEN locus in two cases. In the two other cases, the deletion encompassed PTEN and either two or three contiguous genes without any obvious phenotypic effect, except a possible consequence of PAPSS2 haploinsufficiency on bone growth. Sequence analysis of the four deleted alleles did not reveal identity or sequence homology at the two breakpoints of a same allele, suggesting that a mechanism such as non-homologous recombination of the breakage and reunion type could lead to the occurrence of these deletions. CONCLUSION: Large rearrangements of the PTEN gene can be involved as causing mutation in Cowden disease and MAPH is an efficient screening methodology to detect such a genetic alteration.

Identification of gene polymorphisms of human DNA topoisomerase I in the National Cancer Institute panel of human tumour cell lines.

Topoisomerase 1 (Top1), a nuclear enzyme involved in DNA relaxation, is the target of several anticancer drugs. TOP1 mutations occur in camptothecin-resistant tumour cell lines. We explored, in the NCI panel of 60 human tumour cell lines, whether polymorphic variations in the TOP1 gene could explain differences in drug sensitivity. The 21 exons of the gene were fully studied as well as five intronic domains that had previously been shown to harbour single nucleotide polymorphisms (SNPs) or mutations. PCR products covering the whole exonic sequences or the relevant intronic domains were subjected to denaturing high-performance liquid chromatography. Nucleotide variations were then determined by sequencing. Discrimination between intronic common and variant homozygous samples was performed using a restriction fragment length polymorphism technique. Only one exonic mutation was detected, at the heterozygous state; it occurs in exon 19 of a colon cancer cell line (HCT-15) and consists of a G>A transition at position 75, resulting in a Met675Ile change. The intronic sequences studied harboured the SNPs expected with allelic frequencies between 20 and 40%. Three major haplotypes, generating 92% of the 10 genotypes encountered, were defined as containing none of the intronic SNPs, or three of them, or all of them. No significant relationship was evidenced between Top1 expression and the TOP1 polymorphisms studied. However, when comparing the cytotoxicity of 138 drugs as a function of the genotypes, several drug groups, namely Top1 inhibitors, antifolates and taxanes, had significantly different IC(50)s as a function of the distribution of the intronic SNPs of the TOP1 gene.

[Macrocephaly and multiple hamartoma: a very variable entity]. / Macrocéphalie et hamartomes multiples : une entité d'expression très variable.

UNLABELLED: The Bannayan-Zonana is a dominant autosomal polymalformation syndrome. CASE REPORT: We report a case of Bannayan-Zonana syndrome in a 3-year-old girl, who presented with macrocephaly and a cervical lipoma. The patient's mother had neurofibromatosis I. No mutation in the PTEN gene was found. The slowly progressive lipoma increased with age and the surgical reduction was necessary. COMMENTARIES: Macrocephaly is constant in different syndromes characterized with multiple hamartomas. The multiple hamartomas syndrome represents an entity with a high variability of expression.

[Cowden's disease in an adolescent]. / Maladie de Cowden chez un adolescent.

Cowden's disease is an autosomal dominantly inherited syndrome characterized by mucocutaneous lesions and multiple hamartomas. We report here a 12 years-old boy case with craniomegally, intestinal polyps, epilepsy and multiadenomatous goiter. All the lesions were beginnings. The predisposing genetic defect has been assignated to chromosomal 10 (PTEN-gene mutation). A long term follow-up is necessary because of the risk of malignancies.

WNT pathway and mammary carcinogenesis: loss of expression of candidate tumor suppressor gene SFRP1 in most invasive carcinomas except of the medullary type.

Secreted Frizzled-related protein 1 (SFRP1) encodes a member of a protein family that contains a cysteine-rich domain similar to the WNT-binding site of Frizzled receptors and regulates the WNT pathway. The WNT pathway is frequently altered in human cancers. We have defined the pattern of SFRP1 mRNA expression in the progression of breast cancer. We show that SFRP1 is expressed in the epithelial component of normal breast, in the in situ component of ductal carcinomas and is lost in more than 80% of invasive breast carcinomas except the medullary type. Loss of SFRP1 expression is correlated with the presence of hormonal receptors. Conversely, the maintenance of SFRP1 in carcinomas is correlated with the presence of lymphoplasmocytic stroma. No significant association was observed between SFRP1 status and the level of apoptosis in tumoral cells.

MLH1 and MSH2 protein immunohistochemistry is useful for detection of hereditary non-polyposis colorectal cancer in young patients.

AIMS: Hereditary non-polyposis colorectal cancer is related to germline mutations of DNA mismatch repair genes MLH1 and MSH2, which result in microsatellite instability and loss of protein expression of the corresponding mutated gene in the tumour tissue. METHODS AND RESULTS: MLH1 and MSH2 protein expression was studied by immunohistochemistry in paraffin-embedded surgical samples of 100 colorectal adenocarcinomas occurring before 50 years of age. Absence of tumour cell nuclear staining with positive internal control (normal mucosa, lymphoid follicles) was considered negative. Loss of MLH1 or MSH2 expression was found in 20 cases with microsatellite instability in 15 cases. Twelve of these patients had a family history of colorectal cancer. Compared with MLH1- and MSH2-positive cases, MLH1- or MSH2-deficient colorectal adenocarcinomas were significantly associated on multivariate analysis with a younger age (38 vs. 43 years, P;0.0224), a larger tumour size (60 +/- 6 vs. 46 +/- 2 mm, P=0.0291), an expanding margin (85% vs. 51%, P=0.0159), a higher number of tumour-infiltrating lymphocytes assessed by CD3 immunostaining (202 +/- 48 vs. 33 +/- 4 CD3+ lymphocytes/10 high-power fields, P=0.0039), and a grade 2 Crohn's like lymphoid reaction (70% vs. 9%, P=0.0037). The two groups were not different for tumour site, differentiation, pTNM stage, vascular and perineural invasion, peripheral adenomatous residue, and 5-year survival rates. CONCLUSIONS: MLH1- or MSH2-deficient colorectal carcinomas of young patients exhibit pathological and molecular features similar to hereditary non-polyposis colorectal cancer. This suggests that MLH1 and MSH2 immunohistochemistry is valuable for detecting hereditary non-polyposis colorectal cancer in young patients.

[Li-Fraumeni syndrome: update, new data and guidelines for clinical management]. / Le syndrome de Li-Fraumeni: mise au point, données nouvelles et recommandations pour la prise en charge.

The Li-Fraumeni syndrome (LFS) is an inherited form of cancer, affecting children and young adults, and characterized by a wide spectrum of tumors, including soft-tissue and bone sarcomas, brain tumours, adenocortical tumours and premenopausal breast cancers. In most of the families, LFS results from germline mutations of the tumor suppressor TP53 gene encoding a transcriptional factor able to regulate cell cycle and apoptosis when DNA damage occurs. Recently, germline mutations of hCHK2 encoding a kinase, regulating cell cycle via Cdc25C and TP53, were identified in affected families. The LFS working group recommendations are the following: (i) positive testing (screening for a germline TP53 mutation in a patient with a tumor) can be offered both to children and adults in the context of genetic counseling associated to psychological support, to confirm the diagnosis of LFS on a molecular basis. This will allow to offer to the patient a regular clinical review in order to avoid a delay to the diagnosis of another tumor; (ii) the 3 indications for positive testing are: a proband with a tumor belonging to the narrow LFS spectrum and developed before age 36 and, at least, first- or second-degree relative with a LFS spectrum tumor, before age 46, or a patient with multiple primary tumors, 2 of which belonging to the narrow LFS spectrum, the first being developed before 36 or a child with an adenocortical tumour; (iii) presymptomatic testing must be restricted to adults; (iv) the young age of onset of the LFS tumors the prognosis of some tumors, the impossibility to ensure an efficient early detection and the risk for mutation carriers to develop multiple primary tumors justify that prenatal diagnosis might be considered in affected families.

[Cowden disease and the PTEN gene: a successfully clinical and biological combined approach]. / La maladie de Cowden et le gène PTEN: un exemple d'intègration rèussie entre clinique et biologie.

Cowden disease is an autosomal dominant inherited cancer syndrome characterized by the occurrence of multiple hamartomas, tumors or hyperplastic lesions that may develop in any organ. The disease is related to germline mutation of the PTEN gene, a recently cloned tumor suppressor gene involved in the pathogenesis of sporadic glioblastoma and endometrial carcinoma. It has been shown that the PTEN gene product was a phosphatase able for dephosphorylating a lipid substrate: the phosphatidylinositol (3,4,5)-triphosphate (PIP3). So PTEN appears to negatively control the PI3K-AKT signaling pathway implicated in regulation of cell growth and survival.

Mutations of the human PTEN gene.

PTEN (phosphatase and tensin homolog deleted on chromosome ten), a recently discovered tumor suppressor gene, appears to negatively control the phosphoinositide 3-kinase signaling pathway for regulation of cell proliferation and cell survival by dephosphorylating the phosphatidylinositol 3,4,5-triphosphate. To date, 110 germline PTEN mutations have been reported in patients affected with two tumor predisposing syndromes, each having overlapping clinical features: Cowden disease and Bannayan-Riley-Ruvalcaba syndrome. These germline mutations are scattered along the length of the gene, with the exception of exon 9 (no mutation reported) and exon 1 (only two mutations reported). A mutational hot spot is found in exon 5, which encodes the phosphatase catalytic core motif, and recurrent mutations are also found at CpG dinucleotides suggesting deamination-induced mutations. PTEN has also been found to be defective in a large number of sporadic human tumors. In this article, 332 somatic point mutations of PTEN, occurring in primary tumors or metastasis, have been reviewed. Somatic PTEN mutations are more particularly involved in two types of human cancers: endometrial carcinomas and glioblastomas. In most cases, these somatic mutations result in protein inactivation and, as with germline mutations, recurrent somatic mutations are found in CpG dinucleotides. A mutagenesis by insertion-deletion in repetitive elements is however specifically observed in endometrial carcinomas.

High-resolution integrated map encompassing the breast cancer loss of heterozygosity region on human chromosome 16q22.1.

Loss of heterozygosity (LOH) on the long arm of human chromosome 16 is a common genetic alteration observed in both invasive ductal and invasive lobular breast carcinomas. We have generated a high-resolution integrated map encompassing the smallest region of LOH overlap within chromosome 16q22.1 (SRO2). Southern hybridization experiments using more than 140 probes resulted in the assembly of 152 bacterial large-insert clones into a 2.8-Mb contig covering SRO2. The structure of the contig was verified by long-range mapping using total human genomic DNA, and the contig orientation was determined by fluorescence in situ hybridization. A total of 68 transcripts have been identified in the map. One of the genes residing within SRO2 is the E-cadherin gene, CDH1, which has previously been shown to be mutated in lobular breast carcinomas, resulting in loss of E-cadherin expression. In most cases of ductal carcinoma, which is the major mammary cancer type, E-cadherin is normally expressed, suggesting that other genes within 16q22.1 are involved in the development of this tumor subtype. The high-resolution map presented in this study provides a valuable resource for identification of tumor suppressor genes expected to be involved in the etiology of breast carcinomas.

Thyroid pathologic findings in patients with Cowden disease.

We describe the histologic findings in thyroid glands from six female and five male patients with Cowden disease. The patients were aged 9 to 43 years (mean age, 26 years). The salient thyroid lesions in this syndrome were multicentric follicular adenomas and adenomatous (parenchymatous, hyperplastic) nodules showing a wide range of nonspecific cytoarchitectural patterns. Multiple tiny cellular foci, so-called microadenomas, were also a feature. Specific lesions composed of oxyphil or clear cells, a tumor with features of hyalinizing trabecular adenoma, and an adenolipoma also occurred. Two cases showed a follicular carcinoma in addition to multiple benign follicular cell proliferations. The follicular carcinomas occurred at an older age and were larger in size than the clinically significant benign nodular lesions, suggesting tumor progression. All tumors showed thyroglobulin immunoreactivity and were negative for calcitonin. The histologic findings of a multiple adenomatous goiter or multiple follicular adenomas, particularly in children and young adults, should alert the pathologist and physician to the possibility of an inherited trait, such as Cowden disease, with its implications for family screening. The tumors are usually benign and well demarcated, but, because of multicentricity and increased risk of recurrence or progression to carcinoma, total thyroidectomy should be advocated.