Using Paired-Agent Imaging to Track Changes in Head and Neck Cancers after undergoing Photodynamic Therapy Treatment

Head and neck cancers affect thousands of people across the world, and photodynamic therapy (PDT) has been shown to have great potential to treat said cancers in a noninvasive manner. However, imaging head and neck cancers has been difficult, and molecular changes caused by PDT are not well-understood. Therefore, we propose the use of paired-agent imaging (PAI) to track changes in these cancers after after PDT treatment. For these studies, we primarily used benzoporphyrin derivative monoacid (BPD) for our photosensitizer, which is activated by a 690 nm laser. We first looked at changes in EGFR expression in vitro, and attempted to do so with cell-staining protocols on a 96-well plate using ABY-029 – an anti-EGFR affibody molecule labeled with IRDye 800CW – as a reporter for EGFR expression. Due to cross-talk between the emission filters for the required live/dead dyes on the Odyssey M scanner, we switched to using flow cytometry-based studies. Using these studies, we were able to ascertain a trend in EGFR expression across increasing levels of fluence from the laser, and were able to analyze this trend in both the live and dead cell populations. We then looked at verifying these trends in vivo, where we again used ABY-029 and IRDye 680LT as our targeted and untargeted agents, respectively, for PAI. Using this technique, we were able to determine the same trends in EGFR expression that we had observed in vitro and confirmed this trend in our IHC staining. We also used PAI to look at the binding potential of EGFR across different light doses, and found that the binding potential determined from PAI correlated with the binding potential we had determined from the IHC. In conclusion, PAI using EGFR targeted imaging agents appears to be a promising technique to track early molecular changes in HNSCC in vivo, and that this technique has the potential for applications in patient care

Nerve Repair Chamber

Peripheral nerve injury can lead to severe loss of motor control or sensory integration, posing a significant decrement to quality of life. Yet, using traditional approaches to repair, maximal recovery can take up to 2-3 years to achieve with fewer than 50% of patients ever recovering acceptable sensory and motor function. There is a need to increase axonal alignment while also preventing Wallerian Degeneration of the distal end of the nerve to improve repair. We developed a nerve coupler to be used in a rat sciatic nerve model that holds proximal and distal ends of a nerve together while allowing for polyethylene glycol (PEG) application to stimulate nerve fusion after transection and prevent Wallerian Degeneration. Our solution consists of three modular components optimized for surgical feasibility and nerve regeneration. The coupler is a slim cylindrical shell that allows for the in-vivo transection of the nerve and securement of proximity and orientation with peripheral and central slots. The reservoir is a two part open box which secures the coupler during transection and enables PEG delivery. Prototypes were evaluated for technical requirements and surgical feasibility. In-vivo proof-of-concept tests demonstrated the feasibility of securing the peripheral nerve and enabling PEG application. Further, electrophysiological measurements demonstrated significant improvement in nerve repair using our device compared to traditional approaches. Next steps will include conducting a longitudinal rat study, taking steps forward with intellectual property protection, and further material characterization to enable long-term clinical development

Heme detoxification by heme oxygenase-1 reinstates proliferative and immune balances upon genotoxic tissue injury

Phenotypic changes of myeloid cells are critical to the regulation of premature aging, development of cancer, and responses to infection. Heme metabolism has a fundamental role in the regulation of myeloid cell function and activity. Here, we show that deletion of heme oxygenase-1 (HO-1), an enzyme that removes heme, results in an impaired DNA damage response (DDR), reduced cell proliferation, and increased cellular senescence. We detected increased levels of p16INK4a, H2AXγ, and senescence-associated-β-galactosidase (SA-β-Gal) in cells and tissues isolated from HO-1-deficient mice. Importantly, deficiency of HO-1 in residential macrophages in chimeric mice results in elevated DNA damage and senescence upon radiation-induced injury. Mechanistically, we found that mammalian target of rapamycin (mTOR)/S6 protein signaling is critical for heme and HO-1-regulated phenotype of macrophages. Collectively, our data indicate that HO-1, by detoxifying heme, blocks p16INK4a expression in macrophages, preventing DNA damage and cellular senescence

Labile Heme and Heme Oxygenase-1 Maintain Tumor-Permissive Niche for Endometriosis-Associated Ovarian Cancer

Endometriosis, a painful gynecological condition accompanied by inflammation in women of reproductive age, is associated with an increased risk of ovarian cancer. We evaluated the role of peritoneal heme accumulated during menstrual cycling, as well as peritoneal and lesional macrophage phenotype, in promoting an oncogenic microenvironment. We quantified the heme-degrading enzyme, heme oxygenase-1 (HO-1, encoded by Hmox1) in normal peritoneum, endometriotic lesions and endometriosis-associated ovarian cancer (EAOC) of clear cell type (OCCC). HO-1 was expressed primarily in macrophages and increased in endometrioma and OCCC tissues relative to endometriosis and controls. Further, we compared cytokine expression profiles in peritoneal macrophages (PM) and peripheral blood mononuclear cells (PBMC) in women with endometriosis versus controls as a measure of a tumor-promoting environment in the peritoneum. We found elevated levels of HO-1 along with IL-10 and the pro-inflammatory cytokines (IL-1β, IL-16, IFNγ) in PM but not in PBMC from endometriosis patients. Using LysM-Cre:Hmox1flfl conditional knockout mice, we show that a deficiency of HO-1 in macrophages led to the suppression of growth of ID8 ovarian tumors implanted into the peritoneum. The restriction of ID8 ovarian tumor growth was associated with an increased number of Mac3+ macrophage and B cells in LysM-Cre:Hmox1flfl mice compared to controls. Functional experiments in ovarian cancer cell lines show that HO-1 is induced by heme. Low levels of exogenous heme promoted ovarian cancer colony growth in soft agar. Higher doses of heme led to slower cancer cell colony growth in soft agar and the induction of HO-1. These data suggest that perturbation of heme metabolism within the endometriotic niche and in cancer cells themselves may be an important factor that influences tumor initiation and growth

Scavenging of Labile Heme by Hemopexin Is a Key Checkpoint in Cancer Growth and Metastases

Hemopexin (Hx) is a scavenger of labile heme. Herein, we present data defining the role of tumor stroma-expressed Hx in suppressing cancer progression. Labile heme and Hx levels are inversely correlated in the plasma of patients with prostate cancer (PCa). Further, low expression of Hx in PCa biopsies characterizes poorly differentiated tumors and correlates with earlier time to relapse. Significantly, heme promotes tumor growth and metastases in an orthotopic murine model of PCa, with the most aggressive phenotype detected in mice lacking Hx. Mechanistically, labile heme accumulates in the nucleus and modulates specific gene expression via interacting with guanine quadruplex (G4) DNA structures to promote PCa growth. We identify c-MYC as a heme:G4-regulated gene and a major player in heme-driven cancer progression. Collectively, these results reveal that sequestration of labile heme by Hx may block heme-driven tumor growth and metastases, suggesting a potential strategy to prevent and/or arrest cancer dissemination.Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]