Transient appearance of the mutator phenotype during carcinogenesis as a possible explanation for the lack of mini/microsatellite instability in many late stage tumors

Characteristics and complete genome sequence of the virulent Vibrio alginolyticus phage VAP7, isolated in Hainan, China

A novel Vibrio alginolyticus phage, VAP7, was isolated from seawater collected from Sanya, Hainan province, China. Whole-genome sequencing analysis revealed that phage VAP7 has a linear, double-stranded DNA genome of 144,685 bp with an average G+C content of 41.9% and a high degree of sequence similarity to Vibrio phage VP-1. Annotation results identified 193 open reading frames and one transfer RNA-encoding gene in the phage genome. The morphology and the results of phylogenetic analysis suggest that VAP7 should be classified as a new member of the family Ackermannviridae. Moreover, phage VAP7 grew over a wide pH (5.0-10.0) and temperature (4-40 °C) range. Host-range experiments revealed that VAP7 could infect 31 Vibrio alginolyticus strains. Thus, VAP7 infecting Vibrio alginolyticus strains represents a potential new candidate for use in phage therapy.

DNA instability and human disease

It is now well established that non-Mendelian examples of DNA instability are associated with human disease. Most malignancies are associated with various chromosomal instabilities, such as aneuploidy, gene amplification, and chromosomal deletion. Furthermore, widespread microsatellite instability (MSI) is associated with a variety of tumors, and instability at specific dynamic repeat expansions underlies a family of neurologic disorders. Inactivation of DNA mismatch repair genes results in genomic instabilities affecting microsatellite regions. Mutations in genes involved in DNA polymerization or Okazaki fragment processing are also associated with MSI. Such instabilities convey a 'mutator' phenotype which is pathogenic. The mechanisms controlling trinucleotide repeat expansions are less well understood. Why this type of genomic instability is particularly pathogenic to neurons is also not clear. An understanding of what normally maintains stability is the first step towards preventing such loss of control and maintaining health.

Chemoprevention of epithelial cancers

Over the past 2 years, new insights into mutator and stromal epithelial cell interactions have enhanced the understanding of the carcinogenesis process and have identified potential new approaches to chemoprevention in diverse epithelial sites. Data testing the efficacy of chemopreventive agents in genetically mutated animal carcinogenesis models as screening tools for chemopreventive agents remain immature and point to a continued need for chemical carcinogenesis models to screen for the potential efficacy of chemopreventive agents. The Breast Cancer Prevention Trial is a published, risk-reduction trial that demonstrated a tamoxifen-induced reduction of the risk for breast cancer and focused attention on the clinical use of chemopreventive agents in healthy women. This trial highlighted the potential chemopreventive activity of selective estrogen-receptor antagonists as chemopreventives for breast cancer. New data from animal and human models continue to support the development of nonsteroidal anti-inflammatory agents as chemopreventives for colorectal cancer. Micronutrient- and diet-intervention trials for colorectal chemoprevention present a mixed picture. Although calcium and vitamin supplements, including folate, reduce the recurrence of adenomatous polyps in humans, the effect is small. Fiber supplementation does not reduce the incidence of polyps or colorectal cancer. New approaches for the chemoprevention of esophageal adenocarcinomas, hepatomas, and squamous cell skin cancers represent promising new approaches to the chemoprevention of epithelial cancers.