Multiple genetic abnormalities of 11p15 in Wilms' tumor

Long Noncoding RNAs in Lung Cancer

Despite great progress in research and treatment options, lung cancer remains the leading cause of cancer-related deaths worldwide. Oncogenic driver mutations in protein-encoding genes were defined and allow for personalized therapies based on genetic diagnoses. Nonetheless, diagnosis of lung cancer mostly occurs at late stages, and chronic treatment is followed by a fast onset of chemoresistance. Hence, there is an urgent need for reliable biomarkers and alternative treatment options. With the era of whole genome and transcriptome sequencing technologies, long noncoding RNAs emerged as a novel class of versatile, functional RNA molecules. Although for most of them the mechanism of action remains to be defined, accumulating evidence confirms their involvement in various aspects of lung tumorigenesis. They are functional on the epigenetic, transcriptional, and posttranscriptional level and are regulators of pathophysiological key pathways including cell growth, apoptosis, and metastasis. Long noncoding RNAs are gaining increasing attention as potential biomarkers and a novel class of druggable molecules. It has become clear that we are only beginning to understand the complexity of tumorigenic processes. The clinical integration of long noncoding RNAs in terms of prognostic and predictive biomarker signatures and additional cancer targets could provide a chance to increase the therapeutic benefit. Here, we review the current knowledge about the expression, regulation, biological function, and clinical relevance of long noncoding RNAs in lung cancer.

Trim28 is required for epigenetic stability during mouse oocyte to embryo transition

Phenotypic variability in genetic disease is usually attributed to genetic background variation or environmental influence. Here, we show that deletion of a single gene, Trim28 (Kap1 or Tif1β), from the maternal germ line alone, on an otherwise identical genetic background, results in severe phenotypic and epigenetic variability that leads to embryonic lethality. We identify early and minute epigenetic variations in blastomeres of the preimplantation embryo of these animals, suggesting that the embryonic lethality may result from the misregulation of genomic imprinting in mice lacking maternal Trim28. Our results reveal the long-range effects of a maternal gene deletion on epigenetic memory and illustrate the delicate equilibrium of maternal and zygotic factors during nuclear reprogramming.

Expression of E-cadherin, cadherin-11, α-, β- and γ-catenins in nephroblastomas: relationship with clinicopathological parameters, prognostic factors and outcome

AIM

This study was undertaken to determine the expression of cell adhesion molecules E-cadherin, cadherin-11, and alpha-, beta- and gamma-catenins in nephroblastomas and to correlate this expression with pathological features and known prognostic factors.

METHODS

Immunohistochemistry was performed on 140 cases of nephroblastoma following heat-induced epitope retrieval and using the streptavidin-biotin technique.

RESULTS

E-cadherin was expressed in 75 cases (54%), cadherin-11 in 128 cases (91%), alpha-catenin in 93 cases (66%), beta-catenin in 133 cases (95%) and gamma-catenin in 22 cases (16%). Nuclear localisation of beta-catenin was not demonstrated. There was a statistically significant relationship between the administration of preoperative chemotherapy and the expression of E-cadherin, alpha- and gamma-catenin, respectively. These proteins were more frequently expressed in tumours treated with preoperative chemotherapy. Those tumours that expressed all four proteins (E-cadherin, alpha-, beta- and gamma-catenin) showed a statistically significant association with the administration of preoperative chemotherapy, in contrast to tumours that did not express all four proteins.

CONCLUSION

Nephroblastomas show a heterogeneous distribution of staining for E-cadherin, cadherin-11, alpha-, beta- and gamma-catenins. Tumours treated with preoperative chemotherapy are more likely to express these molecules. The expression status of E-cadherin, cadherin-11 and the catenins in this cohort does not appear to be of prognostic value.

Microsatellite analysis of the adenomatous polyposis coli (APC) gene and immunoexpression of beta catenin in nephroblastoma: a study including 83 cases treated with preoperative chemotherapy

AIMS

To determine whether microsatellite mutations of the adenomatous polyposis coli (APC) gene have pathological or prognostic significance in nephroblastomas and to correlate APC alterations with beta catenin immunoexpression.

METHODS

One hundred nephroblastomas were analysed, 83 of which received preoperative chemotherapy. Normal and tumour DNA was isolated using standard proteinase K digestion and phenol/chloroform extraction from paraffin wax embedded tissue. Polymerase chain reaction using four APC microsatellite markers-D5S210, D5S299, D5S82, and D5S346-was performed and the products analysed. Immunohistochemistry was performed using the LSAB kit with diaminobenzidine as chromogen. Results were correlated with clinicopathological data using the chi(2) test.

RESULTS

Allelic imbalance/loss of heterozygosity was more frequent than microsatellite instability, with 30% of cases showing allelic imbalance/ loss of heterozygosity and 16% showing microsatellite instability. Although there was a significant correlation between the results for individual markers and the clinicopathological data, the overall results do not support a prognostic role for APC in nephroblastoma. Expression of beta catenin was seen in 93% of cases. Staining was predominantly membranous, with epithelium, blastema, and stroma being immunoreactive. Cytoplasmic redistribution was seen in 58% of cases, but no nuclear staining was detected. No significant associations between beta catenin expression and the clinicopathological parameters were found. Kaplan-Meier survival plots showed that patients with loss of membranous staining and pronounced cytoplasmic staining (score, 3) had a significantly shorter survival (p = 0.04; median survival, 5.87 months).

CONCLUSION

Microsatellite analysis of APC and immunoexpression of beta catenin did not provide significant pathological or prognostic information in this cohort of nephroblastomas.

DNA methylation, chromatin boundaries, and mechanisms of genomic imprinting

In mammals, the maternal and paternal genomes are both required for normal embryonic and postnatal development. As a consequence, the majority of genes possess a bi-allelic pattern of expression, with the exception of certain loci where transcription is strictly dependent on parental origin. This alternative, termed genomic imprinting, is an epigenetic form of gene regulation that allows controlled expression of one parental allele. Experimental evidence supports the idea that chromatin organization, DNA methylation, replication timing, genomic domain organization, and more recently methylation-dependent boundary function are key components of imprinting mechanisms. Imprinted genes are mainly required during embryogenesis and development, but loss of controlled imprinting has direct consequences in carcinogenesis. For example, imprinted tumor suppressor genes and proto-oncogenes are highly susceptible to allelic inactivation or in contrast to activation that induces tumorigenic processes. Therefore, genomic imprinting represents one of the more challenging and interesting scientific and medical topics, and especially because a large combinatorial set of possibilities for gene regulation arises from the increasing number of imprinted loci identified.

ARHI is the center of allelic deletion on chromosome 1p31 in ovarian and breast cancers

In our previous work, we had characterized ARHI as an imprinted putative tumor-suppressor gene in ovarian and breast cancers. ARHI is expressed in primary breast and ovarian cell lines but largely absent from the corresponding malignant tumors. Moreover, the non-imprinted functional allele is typically deleted in malignant cells. Since ARHI had been mapped to 1p31, a common deletion site in breast and ovarian cancer and male germ-cell tumors, in this study, we set out to define precisely the physical location of ARHI at 1p31 and to determine if this location lies within the smallest common region of deletion in breast and ovarian cancers. To this end, we first carried out radiation hybrid mapping of ARHI and surrounding markers, followed by a high-resolution study of loss of heterozygosity at 1p31 in 49 ovarian and breast cancers. Combining a radiation hybrid map and a physical map of the region encompassing ARHI, 3 discrete regions of minimal deletion were found at 1p31 in breast and ovarian cancers. ARHI is the most common deletion region at 1p31. Two other less common regions of deletion were found centromeric to this gene. One of them centered on D1S207 and the other one included and was proximal to D1S488. We also confirmed the preferential loss of non-imprinted functional allele in 7 of 9 tumor specimens. These data support the possibility that ARHI is a tumor-suppressor gene and suggest that additional tumor-suppressor genes may lie proximal to ARHI at 1p31. The data obtained from our study should aid in the identification and characterization of genes in this novel imprinted region.

Wilms' tumor and related abnormalities in the fetus and newborn

Mesoblastic nephroma, a benign tumor, is the most common renal neoplasm in neonates. Wilms' tumor (WT) may occur in newborn infants, but is more common in older children. The molecular genetics of WT involves one or more genes located on Chromosome #11 and probably other locations not yet elicidated. Germline mutations cause less than 5% of WTs; most WTs are sporadic. Precursor lesions to WT called nephrogenic rests may be detected before evolution to WT by imaging studies. Developmental anomalies comprising several different syndromes are associated with nephrogenic rests and predisposition to WT. Prospective surveillance for WT may be feasible in high risk infants identified on the basis of physical findings followed by testing for predisposing gene defects and periodic imaging of the kidneys and other organs at risk until the period of risk has ended.

Genomic imprinting and chromatin insulation in Beckwith-Wiedemann syndrome

Genes are recognized as undergoing genomic imprinting when they are capable of being expressed only from the paternal or only from the maternal chromosome. The process can occur coordinately within large physical domains in mammalian chromosomes. One interesting facet of the study of genomic imprinting is that it offers insight into the regulation of large chromosomal regions. Understanding this regulation involves elucidating the cis-acting regulators of gene expression and defining the elements that maintain chromatin insulation, both required for understanding more practically applicable areas of biological research, such as efficient transgene production. This review is focused on the regulation of the imprinted domain of human chromosome 11p15.5, responsible for Beckwith-Wiedemann syndrome (BWS). Recent findings indicate that the maintenance of imprinting within this domain is critically dependent on the stable maintenance of chromatin insulation.

Contribution of clinical teratologists and geneticists to the evaluation of the etiology of congenital malformations alleged to be caused by environmental agents: ionizing radiation, electromagnetic fields, microwaves, radionuclides, and ultrasound

Analysis of these six clinical problems demonstrates the value of a complete clinical evaluation of a child with congenital malformations by an experienced and well-trained physician who is familiar with the fields of developmental biology, teratology , epidemiology, and genetics. Too often, the entire emphasis is placed on epidemiological data that may be meager or insufficient for a rational conclusion when clinical findings that are readily available can provide definitive answers with regard to the etiology of a child's malformations or the merits of an environmental etiology.

Deletion mapping of endocrine tumors localizes a second tumor suppressor gene on chromosome band 11q13

Multiple endocrine neoplasia type 1 syndrome (MEN1, MIM 131100), an autosomal dominant disease, is characterized by parathyroid hyperplasia, pancreatic endocrine tumors, and pituitary adenomas. These tumors also occur sporadically. Both the familial (MEN1) and the sporadic tumors reveal loss of heterozygosity (LOH) for chromosome band 11q13 sequences. Based on prior linkage and LOH analyses, the MEN1 gene was localized between PYGM and D11S460. Recently, the MEN1 gene (menin) has been cloned from sequences 30-kb distal to PYGM. We performed deletion mapping on 25 endocrine tumors (5 MEN1 and 20 sporadic) by using 21 polymorphic markers on chromosome band 11q13. Of these, two (137C7A, 137C7B) were derived from PYGM-containing BAC (bacterial artificial chromosome-137C7) sequences, one from INT2-containing cosmid sequences and the marker D11S4748, a (CA)20 repeat marker that was developed by us. The LOH analysis shows that the markers close to the MEN1 (menin) gene were not deleted in three of the tumors. These tumors, however, showed LOH for distal markers. Thus, the data suggest the existence of a second tumor suppressor gene on chromosome band 11q13.