Carcinogenesis
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Meningiomas are among the most common intracranial tumors and are mostly curable by surgical resection. However, some populations of meningiomas with benign histological profiles show malignant behavior. The reasons for this inconsistency are yet to be ascertained, and novel diagnostic criteria other than the histological one are urgently needed. ⋯ The quantified methylation values of five chosen genes (HOXA6, HOXA9, PENK, UPK3A and IGF2BP1) agreed well with microarray findings, and a scoring system consisting of the five genes significantly correlated with a high frequency of recurrence in an additional validation set of 32 patients. Of particular note is that three cases with malignant transformation already showed hypermethylation at histologically benign stage. In conclusion, a subgroup of meningiomas is characterized by aberrant hypermethylation of the subset of genes in the early stage of tumorigenesis, and our findings highlight the possibility of speculating potential malignancy of meningiomas by assessing methylation status.
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Previous research demonstrates increased prostate cancer risk for pesticide applicators and pesticide manufacturing workers. Although underlying mechanisms are unknown, human biomonitoring studies indicate increased genetic damage (e.g. chromosomal aberrations) with pesticide exposure. Given that the nucleotide excision repair (NER) pathway repairs a broad range of DNA damage, we evaluated interactions between pesticide exposure and 324 single-nucleotide polymorphisms (SNPs) tagging 27 NER genes among 776 prostate cancer cases and 1444 male controls in a nested case-control study of white Agricultural Health Study pesticide applicators. ⋯ Men carrying the homozygous wild-type TT genotype at two correlated CDK7 SNPs, rs11744596 and rs2932778 (r(2) = 1.0), exhibited increased risk with high versus no carbofuran use (OR 2.01; 95% CI 1.31-3.10 for rs11744596; P(interact) = 7.2 × 10(-4); FDR-adjusted P = 0.09). In contrast, we did not observe associations among men with other genotypes at these loci. While requiring replication, our findings suggest a role for NER genetic variation in pesticide-associated prostate cancer risk.
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Retroelements constitute a large part of the human genome. These sequences are mostly silenced in normal cells, but genome-wide DNA hypomethylation in cancers might lead to their re-expression. Whether this re-expression really occurs in human cancers is largely unkown. ⋯ Increased expression of the young AluYa5 and AluYb8 families was restricted to individual tumors. Our findings demonstrate a surprising specificity of changes in expression and DNA methylation of retroelements in prostate cancer. In particular, LINE-1 hypomethylation does not lead to generalized overexpression, but specific human endogenous retrovirus-K proviruses display conspicuous changes in their expression hinting at significant functions during prostate carcinogenesis.
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Comparative Study
Single-nucleotide polymorphisms in DNA repair genes and association with breast cancer risk in the web study.
Base excision repair (BER) and nucleotide excision repair (NER) pathways repair damaged DNA, and polymorphisms in these genes might affect breast cancer susceptibility. We evaluated associations between seven single-nucleotide polymorphisms in four DNA repair genes (ERCC4 rs1799801, XPC rs2227998, rs2228001, rs2228000, OGG1 rs1052133 and XRCC1 rs25487 and rs25486) and breast cancer risk, examining modification by smoking and alcohol consumption, using data from the Western New York Exposures and Breast Cancer Study. Women aged 35-79 years with incident breast cancer (n = 1170) and age- and race-matched controls (n = 2115) were enrolled. ⋯ Postmenopausal women carrying the variant allele of the synonymous XPC polymorphism (rs2227998) were also at borderline significantly increased risk (OR = 1.24; 95% CI 1.01-1.52, heterozygous variant compared with reference; OR = 1.22; 95% CI 1.01-1.48, for combined heterozygous and homozygous variant compared with reference). There was no evidence of genotype-smoking and genotype-alcohol consumption interactions for pre- and postmenopausal women. These results indicate that some of the variants in BER and NER genes may influence risk of postmenopausal breast cancer.
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There is an urgent clinical need for chemotherapeutic and chemopreventive drugs for triple-negative breast cancer (TNBCa). Extending on our recent work, we hypothesize that the herbal compound 1,2,3,4,6-penta-O-galloyl-beta-D-glucose (PGG) can inhibit the growth and metastasis of TNBCa xenograft and target Janus-activated kinase (JAK)-signal transducer and activator of transcription (STAT) 3-signaling axis. Daily oral gavage of 10 mg PGG/kg body wt decreased MDA-MB-231 xenograft weight by 49.3% (P < 0.01) at 40 days postinoculation, whereas weekly intraperitoneal injections of Taxol at the same dosage resulted in a 21.4% reduction (P > 0.1). ⋯ The phosphatase inhibitor pervanadate reversed the PGG-induced downregulation of pSTAT3 and caspase activation. Orally administered PGG can inhibit TNBCa growth and metastasis, probably through anti-angiogenesis, antiproliferation and apoptosis induction. Mechanistically, PGG-induced inhibition of JAK1-STAT3 axis may contribute to the observed in vivo efficacy and the effects on the cellular processes.