Synthesis, Telomerase Evaluation and Anti-Proliferative Studies on Various Series of Diaminoanthraquinone-Linked Aminoacyl Residue Derivatives

Causes of genome instability: the effect of low dose chemical exposures in modern society

Genome instability is a prerequisite for the development of cancer. It occurs when genome maintenance systems fail to safeguard the genome's integrity, whether as a consequence of inherited defects or induced via exposure to environmental agents (chemicals, biological agents and radiation). Thus, genome instability can be defined as an enhanced tendency for the genome to acquire mutations; ranging from changes to the nucleotide sequence to chromosomal gain, rearrangements or loss. This review raises the hypothesis that in addition to known human carcinogens, exposure to low dose of other chemicals present in our modern society could contribute to carcinogenesis by indirectly affecting genome stability. The selected chemicals with their mechanisms of action proposed to indirectly contribute to genome instability are: heavy metals (DNA repair, epigenetic modification, DNA damage signaling, telomere length), acrylamide (DNA repair, chromosome segregation), bisphenol A (epigenetic modification, DNA damage signaling, mitochondrial function, chromosome segregation), benomyl (chromosome segregation), quinones (epigenetic modification) and nano-sized particles (epigenetic pathways, mitochondrial function, chromosome segregation, telomere length). The purpose of this review is to describe the crucial aspects of genome instability, to outline the ways in which environmental chemicals can affect this cancer hallmark and to identify candidate chemicals for further study. The overall aim is to make scientists aware of the increasing need to unravel the underlying mechanisms via which chemicals at low doses can induce genome instability and thus promote carcinogenesis.

Expression of DNA ligase IV is linked to poor prognosis and characterizes a subset of prostate cancers harboring TMPRSS2:ERG fusion and PTEN deletion

DNA ligases are essential for the maintenance of genome integrity as they are indispensable for DNA replication, recombination and repair. The present study was undertaken to gain insights into the prevalence and clinical significance of ligase IV (LIG4) expression in prostate cancer. A total of 11,152 prostate cancer specimens were analyzed by immunohistochemistry for LIG4 expression. Results were compared to follow-up data, ERG status and deletions at PTEN, 3p13, 5q21 and 6q15. LIG4 expression was predominantly localized in the nucleus of the cells with increased intensities in malignant as compared to benign prostate epithelium. In prostate cancer, LIG4 expression was found in 91% of interpretable tumors, including 12% cancers with weak, 23% with moderate and 56% with strong LIG4 positivity. Strong LIG4 expression was tightly linked to advanced Gleason score (P<0.0001) and positive nodal involvement (P=0.03). There was a remarkable accumulation of strong LIG4 expression in tumors harboring TMPRSS2:ERG fusion and PTEN deletions (P<0.0001 each). High LIG4 expression was also tightly related to early biochemical recurrence when all tumors (P<0.0001) or the subsets of ERG-negative (P=0.0004) or ERG-positive prostate cancers (P=0.006) were analyzed. Multivariate analysis including parameters that are available before surgery demonstrated independent association with biochemical recurrence for advanced Gleason grade on biopsy, high preoperative PSA level, high clinical stage (P<0.0001 each) and for LIG4 immunostaining (P=0.03). Our study identifies LIG4 as a predictor of an increased risk for early PSA recurrence in prostate cancer. Moreover, the strong association with TMPRSS2:ERG fusion and PTEN deletions suggest important interactions between these pathways in prostate cancers.