Total inhibition of 1O2-induced oxidative damage to guanine bases of DNA/RNA by turmeric extracts

Mapping the diffusion pattern of 1O2 along DNA duplex by guanine photooxidation with an appended biphenyl photosensitizer

To realize nucleic acid-targeting photodynamic therapy, a photosensitizer should be attached at the optimal position on a complementary oligonucleotide, where a guanine photooxidation is maximized. Here we show the photooxidation of 22 DNA duplexes with varied lengths between a 1O2-generating biphenyl photosensitizer attached at a midchain thymine in a strand and the single guanine reactant in the other strand. The best photooxidation efficiencies are achieved at 9, 10, and 21 base intervals, which coincides with the pitch of 10.5 base pairs per turn in a DNA duplex. The low efficiencies for near and far guanines are due to quenching of the biphenyl by guanine and dilution of 1O2 by diffusion, respectively. The 1O2-diffusion mapping along DNA duplex provides clues to the development of efficient and selective photosensitizer agents for nucleic acid-targeting photodynamic therapy, as well as an experimental demonstration of diffusion of a particle along cylindrical surface in molecular level.

Jadomycins: A potential chemotherapy for multi-drug resistant metastatic breast cancer

Breast cancer causes the most cancer fatalities in women worldwide. Approximately one-third of breast cancers metastasize, or spread from primary tumors to other tissues, and have a 70% 5-year mortality rate. Current breast cancer treatments like doxorubicin and paclitaxel become ineffective when breast cancer cells develop multi-drug resistance and overexpress ATP-binding cassette transporters, as the transporters cause a substantial efflux of the chemotherapies. Jadomycins, a group of molecules isolated from Streptomyces venezuelae ISP5230, are shown to be cytotoxic against a variety of cancers, especially breast cancer. Furthermore, jadomycins retain their cytotoxic properties in multi-drug resistant breast cancer cells, as they are not expelled through ATP-binding cassette transporters. Here, we describe the research that supports the potential use of jadomycins as a novel chemotherapy in the treatment of multi-drug resistant, metastatic breast cancer. We present the supportive findings, as well as the mechanisms of action investigated thus far. These include copper-mediated reactive oxygen species generation, aurora B kinase inhibition, and topoisomerase IIα and IIβ inhibition. We also suggest future directions of jadomycin research, which will help to determine if jadomycins can be used as a breast cancer chemotherapy in clinical practice.