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As scientists develop new technologies, more and more potential cures for cancer are emerging. One prospective method of cancer detection and treatment comes from the field of combinatorial chemistry in a method called One-Bead-One-Compound, originally developed by Dr. Kit S. Lam in 1991.

One-Bead-One-Compound, or OBOC for short, provides a method for efficient and high throughput screening, which is extremely useful in drug screening and drug development. OBOC relies on the development of libraries, screening of library components, and determination of the structures of active compounds. A library is a collection of chemically similar, but unique peptide sequences on beads. The beads are constructed using Split-Mix Synthesis; through this method of synthesis, libraries can be made containing millions of variations of peptide sequences. Once a library is constructed, a screening process will occur in which the beads of a library are incubated with cells that contain the target integrin (transmembrane protein) on the cell surface. After a positive hit is found from the screening process, the chemical structure of this active compound must then be determined. This information can lead to the development of a different, but similar, peptide sequence that has more specific binding. One reason why this technology has so many applications is because of the fact that it is highly customizable–a scientist can modify the type, length, and shape of these peptide sequences to suit their research purposes.

 The beads target transmembrane integrin proteins, shown here.

Image Source: Callista Images

Currently, OBOC technology is being applied to cancer research for cancer detection and targeted treatment. The αvβ3 integrin, expressed on the cell surface of both normal cells and–more highly–on cancerous cells, is involved in numerous physiological processes such as angiogenesis and metastasis of melanoma, glioma, and breast cancers. Because αvβ3 is involved in these processes, the integrin is of great interest in targeted therapy and cancer imaging. In Molecular Cancer Therapy, Xiao W published the discovery of a peptide sequence (on a bead) that binds to the αvβ3 integrin with selectivity and high affinity. Because this peptide sequence, labeled LXW7, selectively binds to αvβ3 with high affinity, it provides an avenue for cancer imaging and targeted therapy for cancers that contain high levels of αvβ3 on cancer cell surfaces.

Once a peptide sequence is found to bind selectively and with high affinity to target integrins, a variety of applications can then be applied. For example, nanoparticles expressing this peptide sequence can be constructed as a form of targeted therapy. These nanoparticles will then target αvβ3 specifically and deliver chemotherapeutic medicine or perform some other function to treat the cancer cells.

Feature Image Source: Bead Bracelet by Sean Winters

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