Chapter 16 - Molecular imaging of proteases in cancer

Abstract

Cancer has been affecting millions of people around the world every year. A plethora of cancer drugs are clinically approved and available, and also surgery and radiotherapy are successful against primary cancers but metastasis is the main reason of death. Proteases are enzymes that are activated in response to stimuli in normal healthy tissues. They are generally involved in regulation of cellular processes such as gene expression, cell generation, proliferation, division, and apoptosis. Tumor progression and metastasis require high oxygen and nutrition supply which are mainly regulated by proteases. Successful inhibition of proteases and hence metastasis is a promising strategy to inhibit and to control cancer. Molecular imaging made possible the accurate and early disease detection, phenotyping, and staging by gathering information about the molecular mechanisms underlying physiological cellular processes in diseased tissues. Molecular imaging for proteases in cancer includes Nuclear Imaging (SPECT, PET, MRI, hyperpolarize MRI), Optical Imaging (Fluorescence Bioluminescence, Raman Spectroscopy), and Photoacoustic and Ultrasound Imaging modalities. These techniques make use of engineered target-specific molecular probes which interact with proteases, providing image contrast and read-out for enzyme abundance at tumor site. Thus molecular imaging has its application in earlier specific detection of disease, efficient therapeutic drug development, and in biomedical research.