Pathology Commons^™

Switches, Excitable Responses And Oscillations In The Ring1b/Bmi1 Ubiquitination System., Lan K Nguyen, Javier Muñoz-García, Helene Maccario, Aaron Ciechanover, Walter Kolch, Boris N Kholodenko

Department of Pathology, Anatomy, and Cell Biology Faculty Papers

In an active, self-ubiquitinated state, the Ring1B ligase monoubiquitinates histone H2A playing a critical role in Polycomb-mediated gene silencing. Following ubiquitination by external ligases, Ring1B is targeted for proteosomal degradation. Using biochemical data and computational modeling, we show that the Ring1B ligase can exhibit abrupt switches, overshoot transitions and self-perpetuating oscillations between its distinct ubiquitination and activity states. These different Ring1B states display canonical or multiply branched, atypical polyubiquitin chains and involve association with the Polycomb-group protein Bmi1. Bistable switches and oscillations may lead to all-or-none histone H2A monoubiquitination rates and result in discrete periods of gene (in)activity. Switches, overshoots …

Early Exposure To Paraquat Sensitizes Dopaminergic Neurons To Subsequent Silencing Of Pink1 Gene Expression In Mice., Hongxia Zhou, Cao Huang, Jianbin Tong, Xugang Xia

Department of Pathology, Anatomy, and Cell Biology Faculty Papers

Environmental exposure, genetic modification, and aging are considered risky for Parkinson's disease (PD). How these risk factors cooperate to induce progressive neurodegeneration in PD remains largely unknown. Paraquat is an herbicide commonly used for weed and grass control. Exposure to paraquat is associated with the increased incidence of PD. In contrast to familial PD, most sporadic PD cases do not have genetic mutation, but may suffer from partial dysfunction of neuron-protective genes as aging. Using conditional transgenic RNAi, we showed that temporal silencing of PINK1 expression in adult mice increased striatal dopamine, the phenotype that could not be induced by …

Perfluorochemical Liquid-Adenovirus Suspensions Enhance Gene Delivery To The Distal Lung., Jeffrey A Kazzaz, Marlene S Strayer, Jichuan Wu, Daniel J Malone, Hshi-Chi Koo, Thomas H Shaffer, Jonathan M Davis, David S Strayer, Marla R Wolfson

Department of Pathology, Anatomy, and Cell Biology Faculty Papers

WE COMPARED LUNG DELIVERY METHODS OF RECOMBINANT ADENOVIRUS (RAD): (1) rAd suspended in saline, (2) rAd suspended in saline followed by a pulse-chase of a perfluorochemical (PFC) liquid mixture, and (3) a PFC-rAd suspension. Cell uptake, distribution, and temporal expression of rAd were examined using A549 cells, a murine model using luciferase bioluminescence, and histological analyses. Relative to saline, a 4X increase in transduction efficiency was observed in A549 cells exposed to PFC-rAd for 2-4 h. rAd transgene expression was improved in alveolar epithelial cells, and the level and distribution of luciferase expression when delivered in PFC-rAd suspensions consistently peaked …

A Conserved Tissue-Specific Homeodomain-Less Isoform Of Meis1 Is Downregulated In Colorectal Cancer., Richard C Crist, Jacquelyn J Roth, Scott A Waldman, Arthur M Buchberg

Department of Microbiology and Immunology Faculty Papers

Colorectal cancer is one of the most common cancers in developed nations and is the result of both environmental and genetic factors. Many of the genetic lesions observed in colorectal cancer alter expression of homeobox genes, which encode homeodomain transcription factors. The MEIS1 homeobox gene is known to be involved in several hematological malignancies and solid tumors and recent evidence suggests that expression of the MEIS1 transcript is altered in colorectal cancer. Despite this potential connection, little is known about the role of the gene in the intestines. We probed murine gastrointestinal tissue samples with an N-terminal Meis1 antibody, revealing …

The Variable Presentations Of Anaplastic Spindle Cell Squamous Carcinoma Associated With Tall Cell Variant Of Papillary Thyroid Carcinoma., Pallavi P Gopal, Kathleen T Montone, Zubair Baloch, Madalina Tuluc, Virginia Livolsi

Department of Pathology, Anatomy, and Cell Biology Faculty Papers

BACKGROUND: In 1976, Hawk and Hazard described the tall cell variant (TCV) of papillary thyroid carcinoma (PTC). While the lesions they described had cytologic features of papillary carcinoma, they showed more aggressive behavior with a greater propensity for extrathyroid extension and lymphovascular invasion than classic PTC. In 1991, Bronner and LiVolsi described a series of patients with TCV that progressed to spindle cell squamous carcinoma (SCSC), a unique form of anaplastic thyroid carcinoma. This study describes the variable clinical and pathologic presentations in 31 patients with anaplastic SCSC arising in association with TCV.

METHODS: The surgical pathology archives as well …

A Compact Guide To The Diagnosis And Management Of Neurofibromatosis Type 1, Timothy Beer, David Strayer, Md, Phd

Department of Pathology, Anatomy, and Cell Biology Resident's Posters

Brief Introduction

Neurofibromatosis type 1 (NF-1) is a multisystem neurocutaneous disorder resulting from mutations in the NF-1 gene on chromosome 17 (q11.2). Mutations in NF-1 result in deficient activity of the tumor suppresor protein neurofibromin, allowing for uncontrolled constitutive activity of the proliferative Raspathway in several neural cell types, including neurons, oligodendrocytes, astrocytes and Schawnn cells. Half of NF-1 cases are inherited in autosomal dominant fashion, while half develop sporadically. The syndrome has 100% penetrance but highly variable expressivity. The prevalence of this syndrome is 1/3,000, making it common enough to warrant YOU, the physician, taking a moment to learn …

Prognostic Significance Of High-Grade Dysplasia In Colorectal Adenomas., A D Toll, D Fabius, T Hyslop, E Pequignot, A J Dimarino, A Infantolino, J P Palazzo

Department of Pathology, Anatomy, and Cell Biology Faculty Papers

Aim  Colonoscopy to detect and remove polyps has contributed to a reduction in colorectal carcinoma. Three-year follow up is recommended for patients considered to be at high risk (at least three adenomas, adenoma ≥ 1 cm, villous or high-grade features). Our study focused on patients diagnosed with high-grade dysplasia with regard to initial management and follow up. Method  A search of patients who had had endoscopic removal of a high-grade adenoma was carried out. Patients with the following were excluded: follow up of < 1 year, polyposis syndromes, prior colon cancer and a diagnosis of adenocarcinoma within 6 months following initial diagnosis. Results  Eighty-three patients treated between 1999 and 2007 for high-grade dysplasia (HGD) in a colorectal adenoma were identified. Over a median follow-up period of 4 years, 53 (64%) developed further adenomatous polyps. Among these, 7% had an adenoma with HGD or an adenocarcinoma. In all these patients, the initial high-grade adenoma was > 1 cm in diameter. Initial follow-up colonoscopy was performed on average 7 months following the initial diagnosis. …

Ercc1 And Rrm1 As Predictors Of Survival And Response In Pancreatic Ductal Adenocarcinoma Treated With Gemcitabine-Based Chemotherapy, Thomas Holdbrook, Kathleen D. Danenberg, Suneeta Satti, Jessica Kline, Charles J. Yeo, Jonathan R. Brody, Peter Mccue, Agnieszka K. Witkiewicz

Department of Surgery Faculty Papers

Conclusion:

In this study, we used RT-PCR and IHC to analyze RRM1 and ERCC1 mRNA and protein expression in PDA specimens. PDA patients with low expression of RRM1 by IHC derived benefit from gemcitabine-based chemotherapy. Assessment of RRM1 mRNA expression was limited by the small sample size. Low ERCC1 expression by RT-PCR was associated with a 2.5 times higher risk of mortality than high expression (p=0.031). There was no association between ERCC1 expression by IHC and survival; however, agreement between mRNA and protein expression was poor for ERCC1. This study demonstrates the ERCC1 and RRM1 expression have an impact on …

Epidermal Growth Factor Receptor Overexpression In Resected Pancreatic Cancer, Amit Mahipal, Mary J. Mcdonald, Agnieszka Witkiewicz, Brian I. Carr

Department of Medical Oncology Faculty Papers

Conclusions:

Membrane EGFR overexpression is associated with poorer clinical outcomes in patients with pancreatic cancer receiving adjuvant therapy post resection.

Cytoplasmic EGFR overexpression is not associated with clinical outcomes.

Expression Of Aldehyde Dehydrogenase In Dysplastic Lesions Arising From Inflammatory Bowel Disease, Adam D. Toll, Bruce M. Boman, Juan P. Palazzo

Department of Pathology, Anatomy, and Cell Biology Faculty Papers

Conclusion: Our study demonstrates ALDH1 is significantly expressed in dysplatic lesions arising from IBD. ALDH1-expression in cancer stem cells suggest an important causative role in the progression to cancer in IBD. Although we found high sensitivity for dysplasia, the specificity was poor. In addition to neoplasia, ALDH1-expressing stem cells proliferate in response to chronic inflammation, accounting for the cases of inflammatory atypia with positive ALDHI1 expression.