Gene Repair in sub‐S phase Cell Populations and Cell Cycle Response to Quadruplex Oligonucleotides

Targeted nucleotide exchange (TNE) relies on the use of a short synthetic oligonucleotide (ODN) designed to be complementary to a target sequence in the genome except for a centrally located mismatch, which directs the desired base change in the DNA. The repair reaction is believed to be enhanced by mechanisms that promote a more open conformation of the DNA, thus, enabling the target site to be more accessible for the binding of the oligonucleotide. One such method is through the modulation of cell cycle progression to increase the population of cells in S phase, wherein targeting of a single base pair is enhanced. Studies aimed at demonstrating the variations in correction in relation to cell cycle measured repair frequency late in the reaction cycle. Our work aims to discern variations in repair levels in subphases of S as cells enter and progress through this phase, in the presence of the oligonucleotide. In addition, we evaluate gene expression patterns of several cell cycle genes that may help denote the changes in cell cycle distribution as a function of gene repair events. Additional research has been performed analyzing gene expression patterns in malignant versus non‐malignant esophageal cancer cells in response to treatment with G‐rich oligonucleotides (GRO). It has been shown that these single‐stranded DNA molecules which are comprised primarily of guanosine residues induce retardation in the progression of the cell cycle, and result in a sub‐G1 population of apoptotic cells. Successful inhibition of growth of malignant, but not nonmalignant, cells has been seen. Thus, G‐rich ODNs may be guiding the selective killing of tumor cells. I am currently analyzing the RNA levels of apoptosis genes incubated with GROs to understand how the cells are responding, and which pathway may be responsible for the induction of apoptosis. Funded by Howard Hughes Medical Institute.