Michael Dunn

Multiple stakeholders play a role in the adoption of personalized medicine, including payers, patients, policy makers, diagnostic manufacturers and providers, and clinicians. These stakeholders span multiple positions, institutions and points of view, and are interested in making sure that each diagnostic launch covers a particular, sometimes contradictory, market need. A growing number of advocacy groups have emerged to unify these stakeholders in this increasingly complex marketplace. This… Show more

Multiple stakeholders play a role in the adoption of personalized medicine, including payers, patients, policy makers, diagnostic manufacturers and providers, and clinicians. These stakeholders span multiple positions, institutions and points of view, and are interested in making sure that each diagnostic launch covers a particular, sometimes contradictory, market need. A growing number of advocacy groups have emerged to unify these stakeholders in this increasingly complex marketplace. This perspective will identify examples of these advocacy efforts in personalized medicine today. It will discuss how far these groups have been able to go, what they are currently pursuing and how they and others can continue to work to move personalized medicine from concept to reality. Show less

Chlorambucil (CLB) treatment is used in chronic lymphocytic leukemia (CLL) but resistance to CLB develops in association with accelerated repair of CLB-induced DNA damage. Phosphorylated histone H2AX (gammaH2AX) is located at DNA double-strand break (DSB) sites; furthermore, it recruits and retains damage-responsive proteins. This damage can be repaired by nonhomologous DNA end-joining (NHEJ) and/or homologous recombinational repair (HR) pathways. A key component of NHEJ is the DNA-dependent… Show more

Chlorambucil (CLB) treatment is used in chronic lymphocytic leukemia (CLL) but resistance to CLB develops in association with accelerated repair of CLB-induced DNA damage. Phosphorylated histone H2AX (gammaH2AX) is located at DNA double-strand break (DSB) sites; furthermore, it recruits and retains damage-responsive proteins. This damage can be repaired by nonhomologous DNA end-joining (NHEJ) and/or homologous recombinational repair (HR) pathways. A key component of NHEJ is the DNA-dependent protein kinase (DNA-PK) complex. Increased DNA-PK activity is associated with resistance to CLB in CLL. We used the specific DNA-PK inhibitor 2-(morpholin-4-yl)-benzo[h]chomen-4-one (NU7026) to sensitize CLL cells to chlorambucil. Our results indicate that in a CLL cell line (I83) and in primary CLL-lymphocytes, chlorambucil plus NU7026 has synergistic cytotoxic activity at nontoxic doses of NU7026. CLB treatment results in G(2)/M phase arrest, and NU7026 increases this CLB-induced G(2)/M arrest. Moreover, a kinetic time course demonstrates that CLB-induced DNA-PK activity was inhibited by NU7026, providing direct evidence of the ability of NU7026 to inhibit DNA-PK function. DSBs, visualized as gammaH2AX, were enhanced 24 to 48 h after CLB and further increased by CLB plus NU7026, suggesting that the synergy of the combination is mediated by NU7026 inhibition of DNA-PK with subsequent inhibition of DSB repair. Show less

In vertebrate cells, Xrcc3 initiates the repair of exogenous induced-DNA breaks during S and G(2)/M phases of the cell cycle by homologous recombination. However, much less is known of the role of Xrcc3 in the response to spontaneous DNA breaks. Using a siRNA approach, we show that depletion of XRCC3 inhibits the proliferation of MCF7 breast cancer cells. This inhibition of replication coincides with the accumulation of DNA breaks, as shown by the comet assay. Cell cycle specific analysis of… Show more

In vertebrate cells, Xrcc3 initiates the repair of exogenous induced-DNA breaks during S and G(2)/M phases of the cell cycle by homologous recombination. However, much less is known of the role of Xrcc3 in the response to spontaneous DNA breaks. Using a siRNA approach, we show that depletion of XRCC3 inhibits the proliferation of MCF7 breast cancer cells. This inhibition of replication coincides with the accumulation of DNA breaks, as shown by the comet assay. Cell cycle specific analysis of gammaH2AX expression shows that S and G2/M phase cells express the highest fraction of gammaH2AX positive cells. This is consistent with replication-dependent accumulation of DNA breaks and deficient homologous recombination. While the induction of gammaH2AX is followed by cell death in parental cells, a p53 knockdown derivative becomes more resistant to XRCC3 depletion-induced death without changes in the levels of gammaH2AX. These results show that XRCC3 is required for the proliferation of MCF7 cells, and that decrease in its expression leads to the accumulation of DNA breaks and the induction of p53-dependent cell death. Show less