Refined deletion mapping in sporadic breast cancer at chromosomal region 8p12-p21 and association with clinicopathological parameters

Association between NEFL Gene Polymorphisms and Neuroblastoma Risk in Chinese Children: A Two-Center Case-Control Study

Neuroblastoma is a lethal tumor that mainly occurs in children. To date, the genetic etiology of sporadic neuroblastoma remains obscure. A previous study identified three neuroblastoma susceptibility loci (rs11994014 G>A, rs2979704 T>C, rs1059111 A>T) in neurofilament light (NEFL) gene. Here, we attempted to evaluate the contributions of these three single nucleotide polymorphisms to neuroblastoma susceptibility in Chinese children. We genotyped these three polymorphisms using subjects from Guangdong province (256 cases and 531 controls) and Henan province (118 cases and 281 controls). Logistic regression models were performed to generate odds ratios and 95% confidence intervals to access the association of these three polymorphisms with neuroblastoma risk. Overall, we failed to provide any evidence supporting the association between these three polymorphisms and neuroblastoma susceptibility, either in single center population or in the combined population. Moreover, such null association was also observed when the samples were stratified by age, gender, tumor sites, and clinical stages. In the future, larger samples from different ethnicities are needed to clarify the role of NEFL gene polymorphisms in neuroblastoma risk.

A Tumor Suppressor Gene Product, Platelet-Derived Growth Factor Receptor-Like Protein Controls Chondrocyte Proliferation and Differentiation

The platelet-derived growth factor receptor-like (PDGFRL) gene is regarded as a tumor suppressor gene. However, nothing is known about the molecular function of PDGFRL. In this study, we initially clarified its function in chondrocytes. Among all cell lines examined, the PDGFRL mRNA level was the highest in chondrocytic HCS-2/8 cells. Interestingly, the proliferation of chondrocytic HCS-2/8 cells was promoted by PDGFRL overexpression, whereas that of the breast cancer-derived MDA-MB-231 cells was inhibited. Of note, in PDGFRL-overexpressing HCS-2/8 cells, the expression of chondrocyte differentiation marker genes, SOX9, ACAN, COL2A1, COL10A1, and ALP, was decreased. Moreover, we confirmed the expression of PDGFRL mRNA in normal cartilage tissue and chondrocytes. Eventually, the expression of PDGFRL mRNA in condrocytes except in the case of hypertrophic chondrocytes was demonstrated in vivo and in vitro. These findings suggest that PDGFRL plays the different roles, depending upon cell types. Particularly, in chondrocytes, PDGFRL may play a new and important role which is distinct from the function previously reported. J. Cell. Biochem. 118: 4033-4044, 2017. © 2017 Wiley Periodicals, Inc.

8p deletion is strongly linked to poor prognosis in breast cancer

Deletions of chromosome 8p occur frequently in breast cancers, but analyses of its clinical relevance have been limited to small patient cohorts and provided controversial results. A tissue microarray with 2,197 breast cancers was thus analyzed by fluorescence in-situ hybridization using an 8p21 probe in combination with a centromere 8 reference probe. 8p deletions were found in 50% of carcinomas with no special type, 67% of papillary, 28% of tubular, 37% of lobular cancers and 56% of cancers with medullary features. Deletions were always heterozygous. 8p deletion was significantly linked to advanced tumor stage (P < 0.0001), high-grade (P < 0.0001), high tumor cell proliferation (Ki67 Labeling Index; P < 0.0001), and shortened overall survival (P < 0.0001). For example, 8p deletion was seen in 32% of 290 grade 1, 43% of 438 grade 2, and 65% of 427 grade 3 cancers. In addition, 8p deletions were strongly linked to amplification of MYC (P < 0.0001), HER2 (P < 0.0001), and CCND1 (p = 0.001), but inversely associated with ER receptor expression (p = 0.0001). Remarkably, 46.5% of 8p-deleted cancers harbored amplification of at least one of the analyzed genes as compared to 27.5% amplifications in 8p-non-deleted cancers (P < 0.0001). In conclusion, 8p deletion characterizes a subset of particularly aggressive breast cancers. As 8p deletions are easy to analyze, this feature appears to be highly suited for future DNA based prognostic breast cancer panels. The strong link of 8p deletion with various gene amplifications raises the possibility of a role for regulating genomic stability.

Common genetic variants in NEFL influence gene expression and neuroblastoma risk

The genetic etiology of sporadic neuroblastoma is still largely obscure. In a genome-wide association study, we identified single-nucleotide polymorphisms (SNP) associated with neuroblastoma at the CASC15, BARD1, LMO1, DUSP12, HSD17B12, HACE1, and LIN28B gene loci, but these explain only a small fraction of neuroblastoma heritability. Other neuroblastoma susceptibility genes are likely hidden among signals discarded by the multiple testing corrections. In this study, we evaluated eight additional genes selected as candidates for further study based on proven involvement in neuroblastoma differentiation. SNPs at these candidate genes were tested for association with disease susceptibility in 2,101 cases and 4,202 controls, with the associations found replicated in an independent cohort of 459 cases and 809 controls. Replicated associations were further studied for cis-effect using gene expression, transient overexpression, silencing, and cellular differentiation assays. The neurofilament gene NEFL harbored three SNPs associated with neuroblastoma (rs11994014: Pcombined = 0.0050; OR, 0.88; rs2979704: Pcombined = 0.0072; OR, 0.87; rs1059111: Pcombined = 0.0049; OR, 0.86). The protective allele of rs1059111 correlated with increased NEFL expression. Biologic investigations showed that ectopic overexpression of NEFL inhibited cell growth specifically in neuroblastoma cells carrying the protective allele. NEFL overexpression also enhanced differentiation and impaired the proliferation and anchorage-independent growth of cells with protective allele and basal NEFL expression, while impairing invasiveness and proliferation of cells homozygous for the risk genotype. Clinically, high levels of NEFL expression in primary neuroblastoma specimens were associated with better overall survival (P = 0.03; HR, 0.68). Our results show that common variants of NEFL influence neuroblastoma susceptibility and they establish that NEFL expression influences disease initiation and progression.

Stage-specific methylome screen identifies that NEFL is downregulated by promoter hypermethylation in breast cancer

Aberrant hypermethylation of promoter regions in specific genes is a key event in the formation and progression of breast cancers, and an increasing number of marker genes have been identified. However, few genes which show methylation change in accordance with the progression of breast cancer have been identified. To identify genes which consistently undergo promoter methylation alterations as the tumor develops from a benign to a malignant form, genome-wide methylation databases of breast cancer cell lines from stage I to stage IV were analyzed. Heatmap and cluster analysis revealed that the genome-wide methylation changes showed a good accordance with tumor progression. Seven out of 14,495 genes were found to be consistently increased alongside the promoter methylation level through the normal cell line to the cancer stage IV cell lines. NEFL, one of the in silico hypermethylated genes in cancer, showed hypermethylation and lower expression in the cancer cell line MDA-MB-231, as well as in cancer tissues (methylation, p<0.05; expression, p<0.01). The expression was restored by inducing demethylation of the promoter in MDA-MB-231 cells. Our findings may lend credence to the possibility of using tumor stage-specific alterations in methylation patterns as biomarkers for estimating prognosis and assessing treatment options for breast cancer.

The role of NEFL in cell growth and invasion in head and neck squamous cell carcinoma cell lines

The neurofilament light polypeptide (NEFL) gene located on chromosome 8q21 is associated with the cancer of several organs and is regarded as a potential tumor suppressor gene. However, the role of the NEFL protein has not yet been studied in cancer cells. Although evidence suggests that there is a correlation between NEFL expression and cancer, studies regarding the role of the NEFL protein have been mostly limited to neurological diseases, such as Charcot-Marie-Tooth's disease (CMT). Most of these studies have not explored the role of NEFL in cancer cell apoptosis and/or invasion. In this study, NEFL expression was manipulated, and apoptosis and invasion were compared in head and neck squamous cell carcinoma cell lines. The results show that the expression of NEFL induces cancer cell apoptosis and inhibits invasion in these cell lines, suggesting that NEFL may play a role in cancer cell apoptosis and invasion.

NEFL mRNA expression level is a prognostic factor for early-stage breast cancer patients

Neurofilament, light polypeptide (NEFL) was demonstrated to be ectopically expressed in breast cancer tissues and decreased in lymph node metastases compared to the paired primary breast cancers in our previous study. Moreover, in several studies, NEFL was regarded as a tumor suppressor gene, and its loss of heterozygosity (LOH) was related to carcinogenesis and metastasis in several types of cancer. To explore the role of NEFL in the progression of breast cancer and to evaluate its clinical significance, we detected the NEFL mRNA level in normal breast tissues, primary breast cancer samples and lymph node metastases, and then analyzed the association between the NEFL expression level and several clinicopathological parameters and disease-free survival (DFS). NEFL mRNA was found to be expressed in 92.3% of breast malignancies and down-regulated in lymph node metastases compared to the paired primary tumors. NEFL mRNA level was lower in primary breast cancers with positive lymph nodes than in cancers with negative lymph nodes. Moreover, a low expression level of NEFL mRNA indicated a poor five-year DFS for early-stage breast cancer patients. Thus, NEFL mRNA is ectopically expressed in breast malignancies and could be a potential prognostic factor for early-stage breast cancer patients.

Role of neurofilament light polypeptide in head and neck cancer chemoresistance

Resistance to cisplatin-based chemotherapy is responsible for therapeutic failure of many common human cancers including cancer of head and neck (HNC). Mechanisms underlying cisplatin resistance remain unclear. In this study, we identified neurofilament light polypeptide (NEFL) as a novel hypermethylated gene associated with resistance to cisplatin-based chemotherapy in HNC. Analysis of 14 HNC cell lines revealed that downregulation of NEFL expression significantly correlated with increased resistance to cisplatin. Hypermethylation of NEFL promoter CpG islands was observed in cell lines as examined by bisulfite DNA sequencing and methylation-specific PCR (MSP) and tightly correlated with reduced NEFL mRNA and protein expression. Furthermore, in patient samples with HNC (n = 51) analyzed by quantitative MSP, NEFL promoter hypermethylation was associated with resistance to cisplatin-based chemotherapy [relative risk (RR), 3.045; 95% confidence interval (CI), 1.459-6.355; P = 0.007] and predicted diminished overall and disease-free survival for patients treated with cisplatin-based chemotherapy. Knockdown of NEFL by siRNA in the highly cisplatin-sensitive cell line PCI13 increased (P < 0.01) resistance to cisplatin. In cisplatin-resistant O11 and SCC25cp cells, restored expression of NEFL significantly increased sensitivity to the drug. Furthermore, NEFL physically associated with tuberous sclerosis complex 1 (TSC1), a known inhibitor of the mTOR pathway, and NEFL downregulation led to functional activation of mTOR pathway and consequentially conferred cisplatin resistance. This is the first study to show a role for NEFL in HNC chemoresistance. Our findings suggest that NEFL methylation is a novel mechanism for HNC chemoresistance and may represent a candidate biomarker predictive of chemotherapeutic response and survival in patients with HNC.

Biological processes, properties and molecular wiring diagrams of candidate low-penetrance breast cancer susceptibility genes

Background

Recent advances in whole-genome association studies (WGASs) for human cancer risk are beginning to provide the part lists of low-penetrance susceptibility genes. However, statistical analysis in these studies is complicated by the vast number of genetic variants examined and the weak effects observed, as a result of which constraints must be incorporated into the study design and analytical approach. In this scenario, biological attributes beyond the adjusted statistics generally receive little attention and, more importantly, the fundamental biological characteristics of low-penetrance susceptibility genes have yet to be determined.

Methods

We applied an integrative approach for identifying candidate low-penetrance breast cancer susceptibility genes, their characteristics and molecular networks through the analysis of diverse sources of biological evidence.

Results

First, examination of the distribution of Gene Ontology terms in ordered WGAS results identified asymmetrical distribution of Cell Communication and Cell Death processes linked to risk. Second, analysis of 11 different types of molecular or functional relationships in genomic and proteomic data sets defined the "omic" properties of candidate genes: i/ differential expression in tumors relative to normal tissue; ii/ somatic genomic copy number changes correlating with gene expression levels; iii/ differentially expressed across age at diagnosis; and iv/ expression changes after BRCA1 perturbation. Finally, network modeling of the effects of variants on germline gene expression showed higher connectivity than expected by chance between novel candidates and with known susceptibility genes, which supports functional relationships and provides mechanistic hypotheses of risk.

Conclusion

This study proposes that cell communication and cell death are major biological processes perturbed in risk of breast cancer conferred by low-penetrance variants, and defines the common omic properties, molecular interactions and possible functional effects of candidate genes and proteins.

An integrative approach to characterize disease-specific pathways and their coordination: a case study in cancer

Background

The most common application of microarray technology in disease research is to identify genes differentially expressed in disease versus normal tissues. However, it is known that, in complex diseases, phenotypes are determined not only by genes, but also by the underlying structure of genetic networks. Often, it is the interaction of many genes that causes phenotypic variations.

Results

In this work, using cancer as an example, we develop graph-based methods to integrate multiple microarray datasets to discover disease-related co-expression network modules. We propose an unsupervised method that take into account both co-expression dynamics and network topological information to simultaneously infer network modules and phenotype conditions in which they are activated or de-activated. Using our method, we have discovered network modules specific to cancer or subtypes of cancers. Many of these modules are consistent with or supported by their functional annotations or their previously known involvement in cancer. In particular, we identified a module that is predominately activated in breast cancer and is involved in tumor suppression. While individual components of this module have been suggested to be associated with tumor suppression, their coordinated function has never been elucidated. Here by adopting a network perspective, we have identified their interrelationships and, particularly, a hub gene PDGFRL that may play an important role in this tumor suppressor network.

Conclusion

Using a network-based approach, our method provides new insights into the complex cellular mechanisms that characterize cancer and cancer subtypes. By incorporating co-expression dynamics information, our approach can not only extract more functionally homogeneous modules than those based solely on network topology, but also reveal pathway coordination beyond co-expression.

Mutation and expression analysis of LZTS1 in ovarian cancer

LZTS1 has been shown to have tumour suppressor activities against prostate and breast cancer and is located within a region of frequent loss of heterozygosity (LOH) at 8p22 in ovarian cancer. We have analysed the expression of LZTS1 in ovarian cancer and found no evidence of loss of expression relative to normal ovarian surface epithelial cells. We have also analysed the coding region of the LZTS1 gene in 87 primary ovarian adenocarcinomas by DHPLC and detected a single silent somatic mutation. These data indicate that LZTS1 is not the target of LOH at 8p22 in ovarian cancer.

Genetic background of different cancer cell lines influences the gene set involved in chromosome 8 mediated breast tumor suppression

Several lines of evidence suggest that chromosome 8 is likely to harbor tumor-suppressor genes involved in breast cancer. We showed previously that microcell-mediated transfer of human chromosome 8 into breast cancer cell line MDA-MB-231 resulted in reversion of these cells to tumorigenicity and was accompanied by changes in the expression of a breast cancer-relevant gene set. In the present study, we demonstrated that transfer of human chromosome 8 into another breast cancer cell line, CAL51, strongly reduced the tumorigenic potential of these cells. Loss of the transferred chromosome 8 resulted in reappearance of the CAL51 phenotype. Microarray analysis identified 78 probe sets differentially expressed in the hybrids compared with in the CAL51 and the rerevertant cells. This signature was also reflected in a panel of breast tumors, lymph nodes, and distant metastases and was correlated with several prognostic markers including tumor size, grading, metastatic behavior, and estrogen receptor status. The expression patterns of seven genes highly expressed in the hybrids but down-regulated in the tumors and metastases (MYH11, CRYAB, C11ORF8, PDGFRL, PLAGL1, SH3BP5, and KIAA1026) were confirmed by RT-PCR and tissue microarray analyses. Unlike with the corresponding nontumorigenic phenotypes demonstrated for the MDA-MB-231- and CAL51-derived microcell hybrids, the respective differentially expressed genes strongly differed. However, the majority of genes in both gene sets could be integrated into a similar spectrum of biological processes and pathways, suggesting that alterations in gene expression are manifested at the level of functions and pathways rather than in individual genes.

ST18 is a breast cancer tumor suppressor gene at human chromosome 8q11.2

We have identified a gene, ST18 (suppression of tumorigenicity 18, breast carcinoma, zinc-finger protein), within a frequent imbalanced region of chromosome 8q11 as a breast cancer tumor suppressor gene. The ST18 gene encodes a zinc-finger DNA-binding protein with six fingers of the C2HC type (configuration Cys-X5-Cys-X12-His-X4-Cys) and an SMC domain. ST18 has the potential to act as transcriptional regulator. ST18 is expressed in a number of normal tissues including mammary epithelial cells although the level of expression is quite low. In breast cancer cell lines and the majority of primary breast tumors, ST18 mRNA is significantly downregulated. A 160 bp region within the promoter of the ST18 gene is hypermethylated in about 80% of the breast cancer samples and in the majority of breast cancer cell lines. The strong correlation between ST18 promoter hypermethylation and loss of ST18 expression in tumor cells suggests that this epigenetic mechanism is responsible for tumor-specific downregulation. We further show that ectopic ST18 expression in MCF-7 breast cancer cells strongly inhibits colony formation in soft agar and the formation of tumors in a xenograft mouse model.

A network of clinically and functionally relevant genes is involved in the reversion of the tumorigenic phenotype of MDA-MB-231 breast cancer cells after transfer of human chromosome 8

Several investigations have supposed that tumor suppressor genes might be located on human chromosome 8. We used microcell-mediated transfer of chromosome 8 into MDA-MB-231 breast cancer cells and generated independent hybrids with strongly reduced tumorigenic potential. Loss of the transferred chromosome results in reappearance of the malignant phenotype. Expression analysis identified a set of 109 genes (CT8-ps) differentially expressed in microcell hybrids as compared to the tumorigenic MDA-MB-231 and rerevertant cells. Of these, 44.9% are differentially expressed in human breast tumors. The expression pattern of CT8-ps was associated with prognostic factors such as tumor size and grading as well as loss of heterozygosity at the short arm of chromosome 8. We identified CT8-ps networks suggesting that these genes act cooperatively to cause reversion of tumorigenicity in MDA-MB-231 cells. Our findings provide a conceptual basis and experimental system to identify and evaluate genes and gene networks involved in the development and/or progression of breast cancer.

Allelic loss in breast cancer

Breast cancer is the most prevalent cancer type in women and allelic loss constitutes one of the commonest genetic alterations in mammary neoplasias. Frequent detection of Loss of Heterozygosity indicates genes with putative tumour suppressor activity in breast carcinomas. Imbalance between two alleles might also be related with increased expression of an oncogene within a locus. Loci exhibiting frequent allelic loss in breast cancer have been detected, spread throughout the genome, and may contain genes with potential significance in breast carcinogenesis. Loss of Heterozygosity patterns in breast cancer give evidence for multiple clonality of the disease, and that accumulation of such lesions is probably implicated in disease development. Studies on deletions of known breast cancer genes suggest interactions with other common genetic events during disease initiation and progression. Allelic loss has been repeatedly associated with adverse characteristics and poor outcome in breast neoplasms. Detection of allelic loss in the serum of breast cancer patients and in premalignant breast lesions could herald the potential for diagnosis of the disease at an early, and thus curable, stage.

Variation near the region of the lipoprotein lipase gene and hypertension or blood pressure levels in Chinese

Essential hypertension (EH) is a common late-onset disease that exhibits complex genetic heterogeneity. Human lipoprotein lipase (LPL) is a rate-limiting enzyme that regulates the catabolism of triglycerides (TG) and chylomicrons (CM). Since dyslipidemia is a common finding in hypertensive patients, the LPL gene is a logical candidate gene that could contribute to the development of hypertension. Using linkage analysis in 148 Chinese hypertensive families, we identified a region of linkage with systolic blood pressure (SBP) and diastolic blood pressure (DBP) that consisted of a 10.6-cM interval defined by markers D8S1145, D8S261, and D8S282 on chromosome 8, which maps between 31 to 41.6 cM from the 8p-telomere contained LPL gene, with statistically significant p values for the marker D8S261 (p = 0.0021 for SBP, and p = 0.0395 for DBP). In the qualitative-trait linkage analysis, evidence for linkage between the marker D8S1145 and EH was found (p = 0.0286). The transmission/disequilibrium test (TDT/S-TDT) also supported a significant linkage-disequilibrium of the allele 3 of D8S261 with EH (chi2 = 8.643, p < 0.01). Furthermore, the marker neurofilament light polypeptide (NEFL) (11 cM centromeric to the LPL gene) appeared to be in linkage with SBP and DBP (p = 0.0329 for SBP; p = 0.0319 for DBP). Additionally, two flanking markers for LPL, D8S511 (9.5 cM telomeric to the LPL gene) and D8S560 (3.2 cM centromeric to the LPL gene), also showed significant linkage with EH (p = 0.0036 for D8S511; p = 0.0115 for D8S560). Previous knowledge about the physiological involvement of LPL in blood pressure regulation and the present findings of variation near the LPL gene support the proposition that a region near the LPL gene or the LPL gene itself might contribute to the individual blood pressure variation in Chinese.

Analysis of DLC-1 expression in human breast cancer

The chromosome region 8p12-p22 shows frequent allelic loss in many neoplasms, including breast cancer (BC). The DLC-1 gene, located on 8p21-p22, might be a candidate tumor suppressor gene in this region. To evaluate the involvement of DLC-1 in breast carcinogenesis we studied DLC-1 mRNA expression in a panel of 14 primary human BC and the corresponding normal breast cells as well as 8 BC cell lines. Low levels or absence of DLC-1 mRNA were observed in 57% of primary BC and 62.5% of BC cell lines, respectively. We could not find any correlation between DLC-1 mRNA expression and deletions at the DLC-1 locus. Transfection of the gene into DLC-1 deficient T-47D cells raised the DLC-1 mRNA level and resulted in inhibition of cell growth and reduced colony-forming capacity. Our results indicate a role of DLC-1 in BC carcinogenesis.

Transfer of chromosome 8 into two breast cancer cell lines: total exclusion of three regions indicates location of putative in vitro growth suppressor genes

Loss of heterozygosity (LOH) of the short arm of chromosome 8 occurs frequently in breast tumors. Fine mapping of the smallest regions of overlap of the deletions indicates that multiple tumor suppressor genes may be located in this region. We have performed microcell-mediated chromosome transfer of chromosome 8 into two breast cancer cell lines, 21MT-1 and T-47D. Twenty-two of the resulting hybrids were characterized extensively with chromosome 8 microsatellite markers and a subset were assayed for growth in vitro and soft agar clonicity. There was no evidence in any of the hybrids for suppression of growth or clonicity that could be attributed to the presence of particular regions of chromosome 8; however, none of the 22 hybrids examined had taken up all of the donor chromosome 8, and in fact there were three regions that contained only one allele of the markers genotyped in all 22 hybrids. These results are consistent with the presence of suppressor genes on the short arm of chromosome 8 causing strong growth suppression that is incompatible with growth in vitro; that is, multiple suppressor genes may exist on the short arm of chromosome 8.

Analysis of the candidate 8p21 tumour suppressor, BNIP3L, in breast and ovarian cancer

Loss of heterozygosity (LOH) on the short arm of chromosome 8, at 8p12-p23, is one of the most frequent genetic events in both breast and ovarian cancer, suggesting the location of a shared tumour suppressor gene. Microcell-mediated chromosome transfer of chromosome 8 suppresses tumorigenicity and growth of colorectal and prostate cancer cell lines, further supporting the presence of a tumour suppressor gene on 8p. We have taken a candidate gene approach to try to identify this tumour suppressor gene at 8p12-p23. BNIP3L, which has sequence homology to pro-apoptotic proteins and the ability to suppress colony formation in soft agar, is located at 8p21, within a region of ovarian cancer LOH, breast cancer LOH and prostate cancer metastasis suppression. BNIP3L expression was assessed by both RT-PCR and Northern blot analysis in breast and ovarian cancer cell lines and found to be expressed at similar levels relative to expression in their respective normal epithelial cell lines. Genetic analysis of BNIP3L in 40 primary ovarian and 25 primary breast tumours identified one somatic, intronic mutation in one ovarian tumour, as well as several polymorphisms, including one resulting in an amino-acid substitution. These data suggest that BNIP3L is unlikely to be the target of 8p LOH in ovarian or breast cancer.

Mutation analysis and mRNA expression of trail-receptors in human breast cancer

The chromosome region 8p12-p22 shows frequent allelic loss in a variety of human malignancies, including breast cancer (BC). The tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-receptors TRAIL-R1, -R2, -R3 and -R4 are located on 8p21-p22 and might be candidate tumor suppressor genes in this region. To evaluate the involvement of TRAIL receptors in breast carcinogenesis, we have analyzed the entire coding region of TRAIL-R2 and the death domain (DD) regions of TRAIL-R1 and -R4 for the detection of somatic mutations in a series of breast tumors, lymph node metastases and BC cell lines. Overall, we detected 1, 11 and 3 alterations in the TRAIL-R1, -R2 and -R4 genes, respectively. Although functional studies have not yet been performed, we assume that most of these alterations do not alter the function of TRAIL-receptors. Additionally, we analyzed individuals from BC families for the detection of TRAIL-R2 germline mutations. One alteration has been found in the Kozak consensus motif at position -4 with respect to the translation initiation AUG [1-4 (C-->A)]. We further studied the mRNA expression of TRAIL and the 4 TRAIL receptors. In BC cell lines, a strongly decreased mRNA expression of TRAIL, TRAIL-R1, -R3 and -R4 was found, whereas the expression of TRAIL-R2 was only slightly reduced. In breast tumors, a 1.2-3.6-fold reduction of mRNA signals of the 5 genes was observed. No correlation was found between the expression level of TRAIL and the receptor mRNAs and clinicopathologic variables and between the expression of TRAIL-R2 and TP53 mutation status and loss of heterozygosity (LOH) at 8p21-p22. Taken together, we cannot exclude the involvement of TRAIL-receptors in BC. Our mutation studies indicate that DD receptor mutations occur at low frequency and are not the primary cause for the altered mRNA expression of TRAIL and TRAIL-receptors in BC.

Evidence for pseudodominant inheritance of atrichia with papular lesions

Atrichia with papular lesions is a rare form of total alopecia, in which mutations in the hairless gene have been shown to underlie the phenotype. In the literature to date, atrichia with papular lesions has generally been reported to be inherited in an autosomal recessive manner. A few rare cases exist, however, in which parent-to-child transmission of atrichia with papular lesions has been documented. In this study, further investigations were carried out into the molecular basis of atrichia with papular lesions in a family with mother-to-son transmission by searching for mutations in the human hairless gene. Specific ally, we wanted to determine whether this case truly represented an example of dominantly inherited atrichia with papular lesions, or whether another mode of inheritance might be responsible for the disorder in this kindred. Pseudodominant inheritance, for example, occurs when an individual with a known recessive disorder has a clinically unaffected partner, but then unexpectedly gives birth to children who are affected with the same recessive disorder as the affected parent, and can easily be distinguished from classical dominant inheritance with molecular diagnosis and haplotype analysis. In the family reported here, we have determined that both the mother and son are, in fact, homozygous for a novel mutation in the hairless gene, R33X. We provide the first evidence for pseudodominant inheritance in atrichia with papular lesions, and at the same time extend our knowledge of pathogenetic mutations in the human hairless gene. Importantly, this information allows revisions in genetic counseling for risk of transmission for individuals in the family, previously impossible in the absence of knowing the genetic basis of atrichia with papular lesions in this unusual kindred.