Novel analogs and a protein target for the napyradiomycins.

摘要

The discovery of novel compounds to fight cancer has been a major goal of the National Cancer Institute since its inception. In accordance with this national goal we are searching for compounds that may not only be effective in fighting cancers directly, but also may shed light on new biological targets that can be used to combat the disease. The napyradiomycins are unique actinomycete metabolites produced by a mixed polyketide and terpenoid biosynthesis. Previous work by the Fenical and Jensen groups has found these molecules are produced only by a probable actinomycete genus designated MAR4. These molecules were briefly explored in the early 1990's for possible use as antibiotics but no comprehensive study of their full biological potential has been undertaken. In our studies we have built a library of known and previously undescribed members of this family and used them to elucidate the likely mechanism of action of the napyradiomycins.;Chapter 1 of the thesis is an introduction to chemotherapeutic drug development including many of the highlights of the last 70 years. Chapter 2 examines the contributions of marine natural products to cancer drug development and examines some of the unique problems in developing marine compounds. Chapter 3 introduces five novel members of the napyradiomycin family (24-28) and examines the effects of structural variations within the class on cytotoxicity measured in HCT-116 colon cancer cells. Chapter three concludes with demonstrating the ability of the napyradiomycins to induce apoptosis in HCT-116 cells using a flow cytometry based assay. Chapter 4 examines the mechanism by which apoptosis is induced in cells treated with napyradiomycins. Although, both caspase-8 and caspase-3 were activated in napyradiomycin induced apoptosis it was found that neither of these caspases were necessary for napyradiomycin induced apoptosis. In Chapter 5 two napyradiomycins CNQ525.510B (27) and A80915C (34) are used to construct coumarin linked fluorescent probes. These probes are used to demonstrate the sub-cellular location of the compounds in the endoplasmic reticulum. Using anti-coumarin antibodies the GRP94, the resident HSP90 of the endoplasmic reticulum, was co-immuno-precipitated with the probes suggesting this is a likely target of the napyradiomycins.