Interplay Between Estrogen and Replication Origins in Breast Cancer DNA Amplification.

摘要

Which is the molecular mechanism that leads to DNA amplification and oncogenes activation in breast cancer cells? This project aims to understand the role of estrogen in inducing re-replication, thus leading to DNA amplifications. I worked on the establishment of cancer cell line models carrying an engineered replication origin to be tested for undergoing DNA amplification after estrogen treatment. Subsequent to some promising preliminary data obtained with MCF7 cells suggesting that estrogen might be able to elicit DNA amplification at this site, the in vitro system used was refined to have multiple possibilities on the selection of cells with DNA amplification. A new reporter construct was built and a second recombinant cell line model established from U2OS/ER-alpha cells was used. The efficiency of the Flp/FRT recombination system for the establishment of MCF7 cells carrying the new construct was too low and did not allow successful recombinants to be obtained during this time period. Moreover, the 17-beta estradiol (E2) treatment of U2OS/ER-alpha recombinant cells was toxic: upon E2 treatment of cells expressing estrogen receptor alpha irreversible cell death was apparent at 24 hours. Because of the limited time of E2 exposure allowed by this system, a new experimental approach of molecular visualization of DNA re-replication has been explored.