First degree female relatives (FDFRs) of breast cancer patients have been reported to have a 2- to 3-fold increase in breast cancer risk as compared with the general population. Assessment of genetic instability (DNA damage and repair efficiency) is an important parameter concerning mutagenesis and carcinogenesis. In an attempt to identify individuals at high risk of breast cancer in the FDFRs of breast cancer patients, two tests were used: the alkaline Comet assay on leucocytes and the micronucleus test (MNT) on buccal epithelial cells. In addition to FDFRs, two other categories of subjects were included: breast cancer patients and controls. The Comet assay was used to study basal DNA damage, DNA susceptibility to a mutagen (N-methyl N-nitro N-nitrosoguanidine) and DNA repair efficiency. In addition, the MNT served as an indicator of chromosome breakage/aneuploidy. A significant increase in DNA damage (basal and after treatment with a mutagen, as well as after allowing repair to take place) and micronucleus frequency was observed from controls to FDFRs and from FDFRs to breast cancer patients. There was considerable variability in the subjects with respect to both of these parameters. Outliers identified among the FDFRs based on 3 SD limits of DNA damage and micronucleus frequency were considered as high risk individuals.

No abstract

The human Y chromosome, because it is enriched in repetitive DNA, has been very intractable to genetic and molecular analyses. There is no previous evidence for developmental stage-and testis-specific transcription from the male-specific region of the Y (MSY). Here, we present evidence for the first time for a developmental stage-and testis-specific transcription from MSY distal heterochromatic block. We isolated two novel RNAs, which localize to Yq12 in multiple copies, show testis-specific expression, and lack active X-homologs. Experimental evidence shows that one of the above Yq12 noncoding RNAs (ncRNAs) trans-splices with CDC2L2 mRNA from chromosome 1p36.3 locus to generate a testis-specific chimeric ␤ sv13 isoform. This 67-nt 5ЈUTR provided by the Yq12 transcript contains within it a Y box protein-binding CCAAT motif, indicating translational regulation of the ␤ sv13 isoform in testis. This is also the first report of trans-splicing between a Y chromosomal and an autosomal transcript.

No abstract

Arsenic (As) is a known human carcinogen; however, very little is known about the health consequences of occupational exposure to As. In the present study, we assessed the genotoxic damage in the blood cells and in the buccal cells of south Indian glass factory workers who are occupationally exposed to As. The As content in the whole blood of 200 workers and 165 controls was evaluated with inductively coupled plasma mass spectrometry. Blood leukocytes from the subjects were monitored for the level of DNA damage using the Comet assay (mean comet tail length); buccal cells were used to determine the frequency of micronuclei (MN). The mean As concentration was significantly higher in the workers (56.76 microg/L) than in the controls (11.74 microg/L) (P < 0.001). The workers also had increased frequencies of MN in the buccal cells and increased levels of DNA damage in leukocytes compared to the controls (P < 0.001). There were significant correlations between the genotoxicity endpoints that were evaluated and blood As concentration, smoking, age, and the duration of working in the factory. Also, a significant correlation was observed between the frequency of MN and comet tail-length for the worker samples. Our findings indicate that chronic occupational exposure to As is genotoxic and that the Comet assay and micronucleus test are useful assays for evaluating genotoxicity in humans occupationally exposed to As.

No abstract

Somatic mutations in mitochondrial DNA (mtDNA) have been demonstrated in various tumors. Mitochondrial D-loop is a non-coding region in the mitochondrial genome, which has essential transcription and replication elements, and alterations in this region may affect both these processes. The D-loop has a poly-C tract (PCT) located between 303 and 315 nucleotides known as D310, which has been identified as a frequent hot spot mutation region in human neoplasia. In the present study, 77 pairs of breast tumor and adjacent non-tumorous tissue samples were analyzed by polymerase chain reaction-single-strand conformational polymorphism, restriction fragment length polymorphism, and sequencing to evaluate the frequency of D310 (PCT) mutations and its association with clinicopathologic parameters of breast cancer. Alterations were detected in 25 of 77 (32.5 %) breast cancer samples; these included 7/25 (28 %) cases with heteroplasmy. This is the first study from Asian Indian breast cancer (BC) patients indicating a relatively high frequency of D310 mutations, suggesting that mtDNA instability at D310 may be a common characteristic of BC. However, 66.7 % of the alterations were observed in stage II BC, indicating that this may be a more important change for early progression of the disease rather than its initiation.

Altered methylation of exonic CpG plays an important role in the enhanced transcription/expression of IGF2 in breast tumors. Methylation analysis of exon 9 CpG can be used as a biomarker for upregulation of IGF2 in breast tumor tissue and maybe developed as a diagnostic test in future.