Cancer cells invade by secreting degradative enzymes which, under normal conditions, are sequestered in lysosomal vesicles. The ability to noninvasively label lysosomes and track lysosomal ...trafficking would be extremely useful to understand the mechanisms by which degradative enzymes are secreted in the presence of pathophysiological environments, such as hypoxia and acidic extracellular pH, which are frequently encountered in solid tumors. In this study, a novel method of introducing a fluorescent label into lysosomes of human mammary epithelial cells (HMECs) was evaluated. Highly glycosylated lysosomal membrane proteins were labeled with a newly synthesized compound, 5-dimethylamino-naphthalene-1-sulfonic acid 5-amino-3,4,6-trihydroxy-tetrahydro-pyran-2-ylmethyl ester (6-O-dansyl-GlcNH2). The ability to optically image lysosomes using this new probe was validated by determining the colocalization of the fluorescence from the dansyl group with immunofluorescent staining of two well-established lysosomal marker proteins, LAMP-1 and LAMP-2. The location of the dansyl group in lysosomes was also verified by using an anti-dansyl antibody in Western blots of lysosomes isolated using isopycnic density gradient centrifugation. This novel method of labeling lysosomes biosynthetically was used to image lysosomes in living HMECs perfused in a microscopy-compatible cell perfusion system.
We present recent updates on our work on developing a fully integrated, miniaturized fiber-optic scanning endomicroscope for performing nonlinear optical imaging including two-photon fluorescence and ...second harmonic generation. We describe our design approaches for significantly improving signal collection efficiency and resolution. Preliminary tissue imaging results will be presented to demonstrate the potential of the nonlinear endomicroscopy technology for diagnostics and image-based guidance.
20 - Molecular Imaging in Cancer Glunde, Kristine; Foss, Catherine A.; Bhujwalla, Zaver M.
Biomedical Information Technology,
2008
Book Chapter
Cancer imaging can be conducted by planar X-ray, computed tomography (CT), ultrasound (US), or magnetic resonance imaging (MRI) scans. Molecular imaging can be defined as “the non-invasive ...visualization of molecular processes.” Molecular imaging uses X-ray, CT, MRI, and US in addition to Xuorescence microscopy and endoscopy as well as nuclear scanning techniques like positron-emission tomography (PET) and single-photon emission tomography (SPECT). Cancer is initiated by and progresses through genetic changes. Initial genetic changes allow cancer cells to evade biologic programs that regulate and limit cellular growth under normal conditions. As tumor growth continues, the unique physiologic microenvironment that cancer cells are exposed to in solid tumors influences tumor progression, aggressiveness, and response to treatment. Molecular imaging can be applied to visualize gene expressionrelated processes such as promoter activity or transcriptional activity, among other processes, in living organisms in vivo. Cancer is a multifaceted disease that requires individual characterization for each tumor but also shares common characteristics. It is important to be able to identify and visualize molecular markers that occur either collectively or individually in various cancers. Such ability is valuable in the quest for the development and application of more potent molecular-targeted cancer therapies that kill malignant tissue while sparing normal tissue. As multimodality imaging instruments become increasingly available, a combined molecular-functional-anatomic imaging approach will become more commonplace for preclinical and clinical investigations and will play an integral role in characterizing tumors to select and validate treatment, screen for sensitivity, and monitor treatment.
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