Molecular Probing and Imaging of Histone Deacetylase Inhibitors in Cancer Treatment

Molecules that inhibit histone deacetylases (HDACs) activity have shown a great promise as anticancer agents since they interfere with cell proliferation and angiogenesis, induce cell differentiation and promote apoptosis. A number of HDACIs (for example: SAHA) have been approved by FDA for the treatment of cancer in different stages of clinical trials. HDAC inhibition proves to be a worthy strategy for cancer therapy. Thus, the distribution and metabolism of HDACIs in vivo are of significant clinical value for diagnosis and assessment of therapeutic efficacy. Molecular imaging is one of the primary tools used to noninvasively evaluate biological processes at the cellular and molecular level in living subjects. Various imaging modalities, including optical bioluminescence/ fluorescence, PET, SPECT, MRI, CT and US are all successfully used to assess the anatomic or functional dissemination of tissues and specific molecular targets, such as imaging molecular interactions, tumor vitality, apoptosis, angiogenesis and response to cancer treatment in the body. The utility of molecular imaging for monitoring HDACIs provides a perfect strategy for deeper understanding about cancer. In this article, the recent progresses of molecular imaging for assessing HDACIs are reviewed. In addition, how imaging can be used, at least experimentally, to assess specific molecular targets is also discussed.