A novel deletion of the MEN1 gene in a large family of multiple endocrine neoplasia type 1 (MEN1) with aggressive phenotype

Context The MEN1 syndrome is associated with parathyroid, pancreatic and pituitary tumours and is caused by mutations in the MEN1 gene. In general, there is no genotype–phenotype correlation. Objectives To characterize a large family with MEN1 with aggressive tumour behaviour: malignant pancreatic endocrine tumours were present in five affected subjects and were the presenting features in three subjects. Design The coding region of MEN1 was sequenced. Gene copy number analysis was performed by multiplex ligation‐dependent probe amplification (MLPA) and array comparative genomic hybridization (aCGH). Loss of heterozygosity (LOH) in tumour tissue was studied by microsatellite analysis. Insulin‐like growth factor II (IGF‐II) and CDKN1C/p57KIP2 expression were investigated by immunohistochemistry. Results Mutation screening by conventional PCR sequence analysis of patients’ peripheral blood DNA did not reveal any mutation in the MEN1 or CDKN1B gene. Gene copy number analysis by MLPA and aCGH demonstrated a novel monoallelic deletion of 5 kb genomic DNA involving the MEN1 promoter and exons 1 and 2. LOH analysis indicated somatic deletion of maternal chromosome 11, including MEN1 locus (11q13) and 11p15 imprinting control regions (ICR). Methylation analysis of ICR demonstrated ICR1 hypermethylation and ICR2 hypomethylation in the tumour specimens. ICR1 and ICR2 control the expression of IGF‐2 and CDKN1C/p57KIP2, respectively. Immunohistochemistry showed that expression of paternally expressed IGF‐2 was up‐regulated and the maternally expressed CDKN1C/p57KIP2 was lost in the pancreatic endocrine tumours. Conclusions Gene copy number analysis by MLPA should be considered in patients with negative conventional mutation screening. Although large MEN1 deletion causes MEN1, disruption of imprinted CDKN1C/p57KIP2 and IGF‐2 gene expression may contribute to tumour progression and aggressive phenotype.     

β1 Integrin is essential for fascin-mediated breast cancer stem cell function and disease progression

Breast cancer remains the second cause of tumor-related mortality in women worldwide mainly due to chemoresistance and metastasis. The chemoresistance and metastasis are attributed to a rare subpopulation with enriched stem-like characteristics, thus called Cancer Stem Cells (CSCs). We have previously reported aberrant expression of the actin-bundling protein (fascin) in breast cancer cells, which enhances their chemoresistance, metastasis and enriches CSC population. The intracellular mechanisms that link fascin with its downstream effectors are not fully elucidated. Here, loss and gain of function approaches in two different breast cancer models were used to understand how fascin promotes disease progression. Importantly, findings were aligned with expression data from actual breast cancer patients. Expression profiling of a large breast cancer dataset (TCGA, 530 patients) showed statistically significant correlation between fascin expression and a key adherence molecule, β1 integrin (ITGB1). In vitro manipulation of fascin expression in breast cancer cells exhibited its direct effect on ITGB1 expression. Fascin-mediated regulation of ITGB1 was critical for several breast cancer cell functions including adhesion to different extracellular matrix, self-renewability and chemoresistance. Importantly, there was a significant relationship between fascin and ITGB1 co-expression and short disease-free as well as overall survival in chemo-treated breast cancer patients. This novel role of fascin effect on ITGB1 expression and its outcome on cell self-renewability and chemoresistance strongly encourages for dual targeting of fascin-ITGB1 axis as a therapeutic approach to halt breast cancer progression and eradicate it from the root.     

Functionally compromised CHD7 alleles in patients with isolated GnRH deficiency

Inactivating mutations in chromodomain helicase DNA binding protein 7 (CHD7) cause CHARGE syndrome, a severe multiorgan system disorder of which Isolated gonadotropin-releasing hormone (GnRH) deficiency (IGD) is a minor feature. Recent reports have described predominantly missense CHD7 alleles in IGD patients, but it is unclear if these alleles are relevant to causality or overall genetic burden of Kallmann syndrome (KS) and normosmic form of IGD. To address this question, we sequenced CHD7 in 783 well-phenotyped IGD patients lacking full CHARGE features; we identified nonsynonymous rare sequence variants in 5.2% of the IGD cohort (73% missense and 27% splice variants). Functional analyses in zebrafish using a surrogate otolith assay of a representative set of these CHD7 alleles showed that rare sequence variants observed in controls showed no altered function. In contrast, 75% of the IGD-associated alleles were deleterious and resulted in both KS and normosmic IGD. In two families, pathogenic mutations in CHD7 coexisted with mutations in other known IGD genes. Taken together, our data suggest that rare deleterious CHD7 alleles contribute to the mutational burden of patients with both KS and normosmic forms of IGD in the absence of full CHARGE syndrome. These findings (i) implicate a unique role or preferential sensitivity for CHD7 in the ontogeny of GnRH neurons, (ii) reiterate the emerging genetic complexity of this family of IGD disorders, and (iii) demonstrate how the coordinated use of well-phenotyped cohorts, families, and functional studies can inform genetic architecture and provide insights into the developmental biology of cellular systems.Inactivating mutations in the gene encoding chromodomain helicase DNA binding protein 7 (CHD7, MIM 608892) cause a severe developmental disorder that affects multiple organ systems and is referred to as CHARGE syndrome (Coloboma, Heart defects, choanal Atresia, Retardation of growth and development, Gonadal defects, and Ear/hearing abnormalities, MIM 214800) (1–3). More than 90% of the reported mutations causing this syndrome are de novo severe truncating lesions that are equally distributed across CHD7’s 37 exons and various functional domains (3–6). The “gonadal defect” in CHARGE patients is in fact hypogonadotropic hypogonadism, which is typically responsive to exogenous gonadotropin-releasing hormone (GnRH) administration: that is, they represent isolated GnRH deficiency (IGD) (7–11).IGD is an inherited reproductive disorder caused by defects in the secretion of GnRH and its action on the anterior pituitary gonadotrope (12). Around 60% of IGD patients also manifest a variety of nonreproductive defects, principally anosmia, which defines Kallmann syndrome (KS), whereas the remainder exhibit a pure nonsyndromic neuroendocrine phenotype, referred to as normosmic IGD (nIGD) (12, 13). In KS, a shared migratory defect of GnRH and olfactory axons produces IGD and anosmia, respectively, whereas other defects result from perturbation of other developmental pathways and processes (14). In contrast, the biological basis of nIGD cases resides in the failure of one or more hypothalamic neuroendocrine systems (12).Several recent reports have suggested that rare sequence variants (RSVs) in CHD7 occur in ∼6% of IGD patients either with (9, 15) or without (8) any features of CHARGE syndrome. Although the initial report implicated CHD7 in both KS and nIGD (8), two subsequent studies detected putative pathogenic CHD7 RSVs in KS patients only (9, 16). However, the possible effects of these IGD-associated CHD7 variants on protein function have not been investigated to date (8, 9, 15, 16). Therefore, we sought to: (i) determine the frequency spectrum, phenotypes, genotypes, and mode of inheritance of CHD7 RSVs in a large, well-characterized cohort of IGD; (ii) characterize functionally a representative spectrum of these IGD- and CHARGE-associated RSVs; and (iii) consider whether differential activity of the protein, or loss thereof, contributes to KS/nIGD/CHARGE or other specific endophenotypes.     

Further delineation of Temtamy syndrome of corpus callosum and ocular abnormalities

Temtamy syndrome is a syndromic form of intellectual disability characterized by ocular involvement, epilepsy and dysgenesis of the corpus callosum. After we initially mapped the disease to C12orf57, we noted a high carrier frequency of an ancient startloss founder mutation [c.1A>G; p.M1?] in our population, and variable phenotypic expressivity in newly identified cases. This study aims to combine 33 previously published patients with 23 who are described here for the first time to further delineate the phenotype of this syndrome. In addition to the known p.M1? founder, we describe four novel homozygous variants, thus increasing the number of Temtamy syndrome‐related C12orf57 variants to seven, all but one predicted to be loss of function. While all patients presented with intellectual disability/developmental delay, the frequency of other phenotypic features was variable: 73.2% (41/56) had epilepsy, 63% (34/54) had corpus callosal abnormalities, 14.5% (8/55) had coloboma, and 16.4% (9/55) had microphthalmia. Our analysis also revealed a high frequency of less recognized features such as congenital heart disease (51.4%), and brain white matter abnormalities (38%, 19/50). We conclude that C12orf57 variants should be considered in the etiology of developmental delay/intellectual disability, even when typical syndromic features are lacking, especially in those who trace their ancestry to Saudi Arabia where a founder C12orf57 mutation is among the most common recessive causes of intellectual disability.

     

The Natural History of Clinical Operational Tolerance After Kidney Transplantation Through Twenty‐Seven Cases

We report here on a European cohort of 27 kidney transplant recipients displaying operational tolerance, compared to two cohorts of matched kidney transplant recipients under immunosuppression and patients who stopped immunosuppressive drugs and presented with rejection. We report that a lower proportion of operationally tolerant patients received induction therapy (52% without induction therapy vs. 78.3%[p = 0.0455] and 96.7%[p = 0.0001], respectively), a difference likely due to the higher proportion (18.5%) of HLA matched recipients in the tolerant cohort. These patients were also significantly older at the time of transplantation (p = 0.0211) and immunosuppression withdrawal (p = 0.0002) than recipients who rejected their graft after weaning. Finally, these patients were at lower risk of infectious disease. Among the 27 patients defined as operationally tolerant at the time of inclusion, 19 still display stable graft function (mean 9 ± 4 years after transplantation) whereas 30% presented slow deterioration of graft function. Six of these patients tested positive for pre‐graft anti‐HLA antibodies. Biopsy histology studies revealed an active immunologically driven mechanism for half of them, associated with DSA in the absence of C4d. This study suggests that operational tolerance can persist as a robust phenomenon, although eventual graft loss does occur in some patients, particularly in the setting of donor‐specific alloantibody.     

Effectiveness of Cetuximab as First-Line Therapy for Patients With Wild-Type KRAS and Unresectable Metastatic Colorectal Cancer in Real-Life Practice: Results of the EREBUS Cohort

Introduction

Few real-life data are available on cetuximab benefit. The EREBUS cohort was performed to assess metastases resection rate, use, safety, and survival outcomes in wild-type KRAS (Kirsten rat sarcoma viral oncogene) patients with initially unresectable metastatic colorectal cancer (mCRC) treated by cetuximab in real practice.

Chemotherapy and targeted agents for colorectal cancer in a real‐life setting anticipate guidelines: the COLCHIC cohort study

Introduction of new agents for the treatment for colorectal cancer (CRC) has been accompanied by the publication of guidelines. The COLCHIC cohort was set up to evaluate CRC treatment practices and the use of these innovative and expensive agents. Patients initiating CRC treatment at the Bordeaux teaching hospital between 1 March 2005 and 1 March 2006 were identified, and treatment courses from 1 March 2005 to 31 December 2006 were studied; 192 patients were included, 188 with analysable data: 43 patients initiated 51 courses for non‐metastatic cancer, 153 initiated 366 courses for metastatic cancer, eight patients initiated courses for both non‐metastatic and metastatic cancer. Most treatments were used for indications found in guidelines published during the study (83.9%). Of the others, nearly half were approved in guidelines published subsequently. In this teaching hospital, prescribing practice was generally in line with recommendations, with an anticipation of future guidelines. This mostly concerned monoclonal antibodies, which were new at the time of the study.