Using differential expression profiling, quantitative two-dimensional (2-D) gel electrophoresis and data mining we recently identified a new prognostic biomarker, Fas-associated death domain (FADD), which is overexpressed in a number of human malignancies such as lung, head and neck, brain and adult male germ cell tumors. Studies in lung cancer revealed that overexpression of FADD significantly associated with poor clinical outcome. Immunohistochemistry-based tissue microarray analysis confirmed the association between FADD over-expression and the poor outcome, and also revealed the presence of nuclear localized phosphorylated FADD (p-FADD). Tumors with increased p-FADD expression also showed elevated NF-?B activation. Taken together, published results from our lab and others suggest a causal relationship between the phosphorylation of FADD and NF-?B activation, a hallmark of an aggressive therapy resistant cancer phenotype. Thereby, we hypothesize that inhibiting FADD phosphorylation in tumor cells may sensitize cancer cells to chemotherapeutic agents. To aid in experimentation of this hypothesis we have resorted to molecular imaging tools and developed a pan FADD kinase reporter (FKR) which non-invasively senses FADD-kinase activity in real time.
In Specific Aim 1, we will characterize the sensitivity and specificity of FKR.
In Specific Aim 2 A we will perform a high throughput screen to identify molecules from a diverse set of compound libraries that target FADD phosphorylation. Utilizing secondary screens with cells expressing either mutant FKR or luciferase, the toxic and less sensitive lead molecules will be eliminated.
In Specific Aim 2 B we will evaluate the relative efficacy of the candidate molecules by quantifying IC50 of the top leads.
In Specific Aim 2 C the specificity of candidate molecules in inhibiting FADD kinases will be investigated using western blotting and protein kinase arrays. The utility of these compounds and their derivatives in the treatment of cancers will be investigated in subsequent years.
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