Inhibition of the CXCL12/CXCR4-axis as preventive therapy for radiation-induced pulmonary fibrosis

Background: A devastating late injury caused by radiation is pulmonary fibrosis. This risk may limit the volume of irradiation and compromise potentially curative therapy. Therefore, development of a therapy to prevent this toxicity can be of great benefit for this patient population. Activation of the chemokine receptor CXCR4 by its ligand stromal cell-derived factor 1 (SDF-1/CXCL12) may be important in the development of radiation-induced pulmonary fibrosis. Here, we tested whether MSX-122, a novel small molecule and partial CXCR4 antagonist, can block development of this fibrotic process. Methodology/Principal Findings: The radiation-induced lung fibrosis model used was C57BL/6 mice irradiated to the entire thorax or right hemithorax to 20 Gy. Our parabiotic model involved joining a transgenic C57BL/6 mouse expressing GFP with a wild-type mouse that was subsequently irradiated to assess for migration of GFP+ bone marrow-derived progenitor cells to the irradiated lung. CXCL12 levels in the bronchoalveolar lavage fluid (BALF) and serum after irradiation were determined by ELISA. CXCR4 and CXCL12 mRNA in the irradiated lung was determined by RNase protection assay. Irradiated mice were treated daily with AMD3100, an established CXCR4 antagonist; MSX-122; and their corresponding vehicles to determine impact of drug treatment on fibrosis development. Fibrosis was assessed by serial CTs and histology. After irradiation, CXCL12 levels increased in BALF and serum with a corresponding rise in CXCR4 mRNA within irradiated lungs consistent with recruitment of a CXCR4+ cell population. Using our parabiotic model, we demonstrated recruitment of CXCR4+ bone marrow-derived mesenchymal stem cells, identified based on marker expression, to irradiated lungs. Finally, irradiated mice that received MSX-122 had significant reductions in development of pulmonary fibrosis while AMD3100 did not significantly suppress this fibrotic process. Conclusions/Significance: CXCR4 inhibition by drugs such as MSX-122 may alleviate potential radiation-induced lung injury, presenting future therapeutic opportunities for patients requiring chest irradiation. © 2013 Shu et al

Combination of an Integrin-Targeting NIR Tracer and an Ultrasensitive Spectroscopic Device for Intraoperative Detection of Head and Neck Tumor Margins and Metastatic Lymph Nodes

Despite major advances in targeted drug therapy and radiation therapy, surgery remains the most effective treatment for most solid tumors. The single most important predictor of patient survival is a complete surgical resection of the primary tumor, draining lymph nodes, and metastatic lesions. Presently, however, 20%–30% of patients with head and neck cancer who undergo surgery still leave the operating room without complete resection because of missed lesions. Thus, major opportunities exist to develop advanced imaging tracers and intraoperative instrumentation that would allow surgeons to visualize microscopic tumors during surgery. The cell adhesion molecule integrin αvβ3 is specifically expressed by tumor neovasculature and invading tumor cells, but not by quiescent vessels or normal cells. Here we report the combined use of an integrin-targeting near-infrared tracer (RGD-IRDye800CW) and a handheld spectroscopic device, an integrated point spectroscopy with wide-field imaging system, for highly sensitive detection of integrin overexpression on infiltrating cancer cells. By using an orthotopic head and neck cancer animal model, we show that this tracer–device combination allows intraoperative detection of not only invasive tumor margins but also metastatic lymph nodes. Correlated histological analysis further reveals that microscopic clusters of 50–100 tumor cells can be detected intraoperatively with high sensitivity and specificity, raising new possibilities in guiding surgical resection of microscopic tumors and metastatic lymph nodes

Monocarbonyl Curcumin Analogues: Heterocyclic Pleiotropic Kinase Inhibitors That Mediate Anticancer Properties

Curcumin is a biologically active component of curry powder. A structurally related class of mimetics possesses similar anti-inflammatory and anticancer properties. Mechanism has been examined by exploring kinase inhibition trends. In a screen of 50 kinases relevant to many forms of cancer, one member of the series (<b>4</b>, EF31) showed ≥85% inhibition for 10 of the enzymes at 5 μM, while 22 of the proteins were blocked at ≥40%. IC₅₀ values for an expanded set of curcumin analogues established a rank order of potencies, and analyses of IKKβ and AKT2 enzyme kinetics for <b>4</b> revealed a mixed inhibition model, ATP competition dominating. Our curcumin mimetics are generally selective for Ser/Thr kinases. Both selectivity and potency trends are compatible with protein sequence comparisons, while modeled kinase binding site geometries deliver a reasonable correlation with mixed inhibition. Overall, these analogues are shown to be pleiotropic inhibitors that operate at multiple points along cell signaling pathways

CXCR4 antagonists inhibit radiation-induced PF.

<p>Mice underwent hemithoracic irradiation (20-Gy) and treated with CXCR4 antagonists or their corresponding vehicle controls (n=10/group). <i>A</i>, Lungs were evaluated histologically after trichrome staining (dark bars) or by CT scan (light bars) at 20-weeks post-irradiation. Histologic evaluation was scored (0-12) in each lung as described in the Methods section. CT scan evaluation was scored as the percent volume of lung with density>-200 HU. In all assessments, the vehicle controls values were normalized to 100% with drug-treated values expressed relative to corresponding controls to evaluate the efficacy of the CXCR4 antagonists in attenuating radiation-induced PF. Error bar represents SEM. * indicates statistically significant difference (p<0.05) compared with vehicle controls. <i>B</i>, Representative micrographs of trichrome staining are shown in 4X and 40X magnification.</p

Assessing Treatment Response of Glioblastoma to an HDAC Inhibitor Using Whole-Brain Spectroscopic MRI

Histone deacetylases regulate a wide variety of cellular functions and have been implicated in redifferentiation of various tumors. Histone deacetylase inhibitors (HDACi) are potential pharmacologic agents to improve outcomes for patients with gliomas. We assessed the therapeutic efficacy of belinostat (PXD-101), an HDACi with blood–brain barrier permeability. Belinostat was first tested in an orthotopic rat glioma model to assess in vivo tumoricidal effect. Our results showed that belinostat was effective in reducing tumor volume in the orthotopic rat glioma model in a dose-dependent manner. We also tested the antidepression activity of belinostat in 2 animal models of depression and found it to be effective. Furthermore, we confirmed that myo-inositol levels improved by belinostat treatment in vitro. In a human pilot study, it was observed that belinostat in combination with chemoradiation may delay initial recurrence of disease. Excitingly, belinostat significantly improved depressive symptoms in patients with glioblastoma compared with control subjects. Finally, spectroscopic magnetic resonance imaging of 2 patient cases from this pilot study are presented to indicate how spectroscopic magnetic resonance imaging can be used to monitor metabolite response and assess treatment effect on whole brain. This study highlights the potential of belinostat to be a synergistic therapeutic agent in the treatment of gliomas

Quantification of PF in a hemithoracic irradiation model.

<p><i>A</i>, Representative portal image of three mice receiving right hemithoracic radiation (region of treatment in pink) is shown. <i>B</i>, VelocityAI interface was used to show representative axial/coronal/sagittal slices of reconstructed CT image set with the right lung as 3D-volume of interest contoured (red). <i>C</i>-<i>E</i>, Representative H&E-stained lung slides (<i>C</i>), corresponding axial CT images (<i>D</i>) and plots of HU versus %volume (<i>E</i>) at C (untreated), 8(1), 12(2), 16(3), and 20(4) weeks after irradiation are shown. </p

CXCL12 and CXCR4 expression in lungs of mice after 20 Gy radiation.

<p>Graphs of CXCL12 levels (ng/ml) (n=5 or 6) measured by ELISA in (<i>A</i>) serum and (<i>B</i>) BALF as well as (<i>C</i>) CXCL12 and (<i>D</i>) CXCR4 normalized mRNA levels (n=5) measured by RNase protection assay in lungs at 0, 1, 3, 7, 14 and 28-days post-irradiation (whole thorax) are shown. Error bars represent SEM. * indicates statistically significant difference (p<0.05) compared with value at day-0. </p

Migration of BMDMSCs to the bleomycin-injured lungs.

<p><i>A</i>, Parabiont consisting of GFP-positive (GFP+) and wild-type (GFP-) mouse is shown. <i>B</i>, Flow cytometry analysis of leukocytes from the three sets of pooled blood of three parabionts (experiment using 9 parabiont pairs) showing roughly half of the cells show green fluorescence consistent with GFP positivity. <i>C</i>, Flow cytometry analysis of 200,000 cells prepared from three lungs of bleomycin- (black) or saline-treated (white) parabionts at day-21 are shown. Graphs compare percent of total cells that is GFP+(left) and percent of GFP+cells that is CD45-/CD44+/CD105+ (right). Error bars represent standard error of the mean (SEM). </p