Targeting Cancer Protein Profiles with Split-Enzyme Reporter Fragments to Achieve Chemical Resolution for Molecular Imaging.

摘要

Mutational events that drive a normal cell to become a cancer cell require the coordinated overexpression of multiple biomarkers. Unique biomarker combinations can create dynamic, physiologic patterns at different stages of cancer development. The assignment of protein expression patterns, or protein profiling, to delineate differences between normal tissues and developing cancer is gaining momentum as a critical instrument in aiding diagnosis, tailoring therapeutics, and predicting clinical outcomes. These proteomic studies, however, investigate changes in protein expression in cell lines and bulk tissue specimens at the gross proteomic level. While powerful, this technique fails to account for the heterogeneity of most tumors since the histopathology associated with many cancers encompasses only a small fraction of the total number of cells present in a tissue section. To date, it is impossible to visualize these cancer biomarker patterns in situ, which define the status of the cell, both non-invasively and in vivo. We present a major leap in cancer imaging ideology to develop a novel molecular imaging paradigm that utilizes multiple cellular targets to generate imageable signals in the same cell thereby achieving chemical resolution. The objective of our proposed research is to develop a new imaging platform consisting of targeted-trans-complementing reporter fragments to simultaneously image the cancer signature in vivo and in real time. A number of unique advantages of this imaging platform are envisaged, such as: 1) increased specificity; 2) multi-marker imaging at the cellular level; and 3) ability to recognize distinct genetic patterns among different tumor types and grades. In the proposed experiments, we will conjugate each reporter fragment to one of two different ligands to simultaneously target and image in vivo, via enzyme reporter reconstruction in situ, a molecular signature consisting of two or more different targets.