title: REDOX IMAGING OF THE p53-DEPENDENT MITOCHONDRIAL REDOX STATE IN COLON CANCEREX VIVO.
abstract: The mitochondrial redox state and its heterogeneity of colon cancer at tissue level have not been previously reported. Nor has how p53 regulates mitochondrial respiration been measured at (deep) tissue level, presumably due to the unavailability of the technology that has sufficient spatial resolution and tissue penetration depth. Our prior work demonstrated that the mitochondrial redox state and its intratumor heterogeneity is associated with cancer aggressiveness in human melanoma and breast cancer in mouse models, with the more metastatic tumors exhibiting localized regions of more oxidized redox state. Using the Chance redox scanner with an in-plane spatial resolution of 200μm, we imaged the mitochondrial redox state of the wild-type p53 colon tumors (HCT116 p53wt) and the p53-deleted colon tumors (HCT116 p53-/-) by collecting the fluorescence signals of nicotinamide adenine dinucleotide (NADH) and oxidized flavoproteins [Fp, including flavin adenine dinucleotide (FAD)] from the mouse xenografts snap-frozen at low temperature. Our results show that: (1) both tumor lines have significant degree of intratumor heterogeneity of the redox state, typically exhibiting a distinct bi-modal distribution that either correlates with the spatial core-rim pattern or the "hot/cold" oxidation-reduction patches; (2) the p53-/-group is significantly more heterogeneous in the mitochondrial redox state and has a more oxidized tumor core compared to the p53wtgroup when the tumor sizes of the two groups are matched; (3) the tumor size dependence of the redox indices (such as Fp and Fp redox ratio) is significant in the p53-/-group with the larger ones being more oxidized and more heterogeneous in their redox state, particularly more oxidized in the tumor central regions; (4) the H&E staining images of tumor sections grossly correlate with the redox images. The present work is the first to reveal at the submillimeter scale the intratumor heterogeneity pattern of the mitochondrial redox state in colon cancer and the first to indicate that at tissue level the mitochondrial redox state is p53 dependent. The findings should assist in our understanding on colon cancer pathology and developing new imaging biomarkers for clinical applications.
authors.affiliation: Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA ; Britton Chance Laboratory of Redox Imaging, Johnson Research Foundation, Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
authors.forename: He N
authors.initials: HN
authors.lastname: Xu
authors.affiliation: Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA ; Britton Chance Laboratory of Redox Imaging, Johnson Research Foundation, Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
authors.forename: Min
authors.initials: M
authors.lastname: Feng
authors.affiliation: Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA ; Britton Chance Laboratory of Redox Imaging, Johnson Research Foundation, Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
authors.forename: Lily
authors.initials: L
authors.lastname: Moon
authors.affiliation: Department of Medicine, Penn State Hershey Medical Center and Penn State College of Medicine, Hershey, PA, USA.
authors.forename: Nathan
authors.initials: N
authors.lastname: Dolloff
authors.affiliation: Hematology/Oncology, Penn State Hershey Medical Center, Hershey, PA, USA.
authors.forename: Wafik
authors.initials: W
authors.lastname: El-Deiry
authors.affiliation: Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA ; Britton Chance Laboratory of Redox Imaging, Johnson Research Foundation, Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA ; Hematology/Oncology, Penn State Hershey Medical Center, Hershey, PA, USA ; Abramson Cancer Center, University of Pennsylvania, Philadelphia, PA, USA ; Institute of Translational Medicine and Therapeutics, University of Pennsylvania, Philadelphia, PA, USA.
authors.forename: Lin Z
authors.initials: LZ
authors.lastname: Li
keywords: HCT116; NADH; flavoprotein; intratumor heterogeneity; necrotic; p53 null