Genetic instability is a major feature of tumor cells and is associated with the process of carcinogenesis in humans. In many cases, such instability occurs during the S phase and is due to DNA replication defects. The enzymatic machinery of replication used to copy and reproduce the DNA is called “replisome”. Replisome progression is subject to numerous control systems because its disruption can produce changes in the genome. DNA replication may be hampered by barriers that slow, temporarily stop or block the progression of replicative DNA polymerases. These obstacles may have different causes: a) secondary structures in DNA, b) complex DNA-protein, c) changes in chromatin and d) DNA damage. If the arrested replication forks are not appropriately processed , chromosomal rearrangements (translocations, inversions or deletions) may occur and contribute to early stages of carcinogenesis. In this context, we study the functions of translesional DNA polymerases that may contribute to bypass break sites. Actually, we think that it is important to understand these aspects of DNA replication, both in terms of mechanisms of emergence of such obstacles and their functional consequences.
We study the molecular mechanisms of replication fork barriers induced by replicative stress, using human cell lines models. To do this, we use technologies such as two-dimensional gels to analyze intermediate forms of DNA replication, “ChIP-on-chip” methods and high-throughput sequencing. This allows us to locize the sites of replication fork pauses in the entire genome. In the long run, our work will help us better understand how defects caused by abnormal arrest of replication forks can contribute to the development of diseases associated with genomic instability, especially cancers. Moreover, thanks to high throughput approaches we explore the cancer genomic databases to identify molecular alterations that affect DNA metabolism and its control during the cell cycle.