Medicine and Health Sciences Commons^™

Saturated Free Fatty Acids Induce Cholangiocyte Lipoapoptosis, Sathish Kumar Natarajan, Sally A. Ingham, Ashley M. Mohr, Cody J. Wehrkamp, Anuttoma Ray, Sohini Roy, Sophie C. Cazanave, Mary A. Smith, Justin L. Mott

Journal Articles: Biochemistry & Molecular Biology

Recent studies have identified a cholestatic variant of nonalcoholic fatty liver disease (NAFLD) with portal inflammation and ductular reaction. Based on reports of biliary damage, as well as increased circulating free fatty acids (FFAs) in NAFLD, we hypothesized the involvement of cholangiocyte lipoapoptosis as a mechanism of cellular injury. Here, we demonstrate that the saturated FFAs palmitate and stearate induced robust and rapid cell death in cholangiocytes. Palmitate and stearate induced cholangiocyte lipoapoptosis in a concentration-dependent manner in multiple cholangiocyte-derived cell lines. The mechanism of lipoapoptosis relied on the activation of caspase 3/7 activity. There was also a significant up-regulation …

Ethanol-Induced Oxidant Stress Modulates Hepatic Autophagy And Proteasome Activity., Terrence M. Donohue, Paul G. Thomes

Journal Articles: Biochemistry & Molecular Biology

In this review, we describe research findings on the effects of alcohol exposure on two major catabolic systems in liver cells: the ubiquitin-proteasome system (UPS) and autophagy. These hydrolytic systems are not unique to liver cells; they exist in all eukaryotic tissues and cells. However, because the liver is the principal site of ethanol metabolism, it sustains the greatest damage from heavy drinking. Thus, the focus of this review is to specifically describe how ethanol oxidation modulates the activities of the UPS and autophagy and the mechanisms by which these changes contribute to the pathogenesis of alcohol-induced liver injury. Here, …

Unbiased Analysis Of Pancreatic Cancer Radiation Resistance Reveals Cholesterol Biosynthesis As A Novel Target For Radiosensitisation., Joshua J. Souchek, Michael J. Baine, Chi Lin, Satyanarayana Rachagani, Suprit Gupta, Sukhwinder Kaur, K Lester, D Zheng, S Chen, Lynette Smith, A Lazenby, Sonny L. Johansson, Maneesh Jain, Surinder K. Batra

Journal Articles: Biochemistry & Molecular Biology

BACKGROUND: Despite its promise as a highly useful therapy for pancreatic cancer (PC), the addition of external beam radiation therapy to PC treatment has shown varying success in clinical trials. Understanding PC radioresistance and discovery of methods to sensitise PC to radiation will increase patient survival and improve quality of life. In this study, we identified PC radioresistance-associated pathways using global, unbiased techniques.

METHODS: Radioresistant cells were generated by sequential irradiation and recovery, and global genome cDNA microarray analysis was performed to identify differentially expressed genes in radiosensitive and radioresistant cells. Ingenuity pathway analysis was performed to discover cellular pathways …

Novel Role Of Pancreatic Differentiation 2 In Facilitating Self-Renewal And Drug Resistance Of Pancreatic Cancer Stem Cells., Arokia P. Vaz, Moorthy P. Ponnusamy, Satyanarayana Rachagani, P Dey, Apar Kishor Ganti, Surinder K. Batra

Journal Articles: Biochemistry & Molecular Biology

BACKGROUND: Cancer stem cells (CSCs) contribute towards disease aggressiveness and drug resistance. Specific identification of CSC maintenance genes and targeting can improve the efficiency of currently available treatment modalities. Pancreatic differentiation 2 (PD2) has a major role in the self-renewal of mouse embryonic stem cells. In the present study, we investigated the role of PD2 in pancreatic CSCs.

METHODS: Characterisation of CSCs and non-CSCs from mouse models, pancreatic cancer cells and human tissues by CSC and self-renewal marker analysis using confocal assay. Effect of PD2 knockdown in CSCs (after gemcitabine treatment) was studied by immunoblot and apoptosis assays.

RESULTS: A …

Stag2 Promotes Error Correction In Mitosis By Regulating Kinetochore–Microtubule Attachments, Marianna Kleyman, Lilian Kabeche, Duane A. Compton

Dartmouth Scholarship

Mutations in the STAG2 gene are present in ∼20% of tumors from different tissues of origin. STAG2 encodes a subunit of the cohesin complex, and tumors with loss-of-function mutations are usually aneuploid and display elevated frequencies of lagging chromosomes during anaphase. Lagging chromosomes are a hallmark of chromosomal instability (CIN) arising from persistent errors in kinetochore-microtubule (kMT) attachment. To determine whether the loss of STAG2 increases the rate of formation of kMT attachment errors or decreases the rate of their correction, we examined mitosis in STAG2-deficient cells. STAG2 depletion does not impair bipolar spindle formation or delay mitotic progression. Instead, …

Diagnosis Of Pancreatic Neoplasms Using A Novel Method Of Dna Methylation Analysis Of Mucin Expression In Pancreatic Juice., Seiya Yokoyama, Sho Kitamoto, Michiyo Higashi, Yuko Goto, Taro Hara, Dai Ikebe, Taketo Yamaguchi, Yoshifumi Arisaka, Toru Niihara, Hiroto Nishimata, Sadao Tanaka, Kyoichi Takaori, Surinder K. Batra, Suguru Yonezawa

Journal Articles: Biochemistry & Molecular Biology

Mucins (MUC) play crucial roles in carcinogenesis and tumor invasion in pancreatic ductal adenocarcinoma (PDAC) and intraductal papillary mucinous neoplasms (IPMNs). Our immunohistochemistry (IHC) studies have shown a consensus position on mucin expression profiles in pancreatic neoplasms as follows: MUC1-positive but MUC2-negative expression in PDACs; MUC1-negative but MUC2-positive expression in intestinal-type IPMNs (dangerous type); MUC1-negative and MUC2-negative expression in gastric-type IPMNs (safe type); High MUC4 expression in PDAC patients with a poor outcome; and MUC4-positive expression in intestinal-type IPMNs. We also showed that three mucin genes (MUC1, MUC2 and MUC4) expression in cancer cell line was regulated by DNA methylation. …

Isoform- And Species-Specific Control Of Inositol 1,4,5-Trisphosphate (Ip3) Receptors By Reactive Oxygen Species., Száva Bánsághi, Tünde Golenár, Muniswamy Madesh, György Csordás, Satish P. Ramachandrarao, Kumar Sharma, David I Yule, Suresh K Joseph, György Hajnóczky

Department of Pathology, Anatomy, and Cell Biology Faculty Papers

Reactive oxygen species (ROS) stimulate cytoplasmic [Ca(2+)] ([Ca(2+)]c) signaling, but the exact role of the IP3 receptors (IP3R) in this process remains unclear. IP3Rs serve as a potential target of ROS produced by both ER and mitochondrial enzymes, which might locally expose IP3Rs at the ER-mitochondrial associations. Also, IP3Rs contain multiple reactive thiols, common molecular targets of ROS. Therefore, we have examined the effect of superoxide anion (O2) on IP3R-mediated Ca(2+) signaling. In human HepG2, rat RBL-2H3, and chicken DT40 cells, we observed [Ca(2+)]c spikes and frequency-modulated oscillations evoked by a O2 donor, xanthine (X) + xanthine oxidase (XO), dose-dependently. …

Inhibition Of Rac1 Gtpase Sensitizes Pancreatic Cancer Cells To Γ-Irradiation, Y Yan, Ashley L. Hein, Asserewou Etekpo, Katrina M. Burchett, Chi Lin, Charles A. Enke, Surinder K. Batra, Kenneth Cowan, Michel M. Ouellette

Journal Articles: Biochemistry & Molecular Biology

Radiation therapy is a staple treatment for pancreatic cancer. However, owing to the intrinsic radioresistance of pancreatic cancer cells, radiation therapy often fails to increase survival of pancreatic cancer patients. Radiation impedes cancer cells by inducing DNA damage, which can activate cell cycle checkpoints. Normal cells possess both a G1 and G2 checkpoint. However, cancer cells are often defective in G1 checkpoint due to mutations/alterations in key regulators of this checkpoint. Accordingly, our results show that normal pancreatic ductal cells respond to ionizing radiation (IR) with activation of both checkpoints whereas pancreatic cancer cells respond to IR with G2/M arrest …

Novel Roles For Actin In Mitochondrial Fission, Anna L. Hatch, Pinar S. Gurel, Henry N. Higgs

Dartmouth Scholarship

Mitochondrial dynamics, including fusion, fission and translocation, are crucial to cellular homeostasis, with roles in cellular polarity, stress response and apoptosis. Mitochondrial fission has received particular attention, owing to links with several neurodegenerative diseases. A central player in fission is the cytoplasmic dynamin-related GTPase Drp1, which oligomerizes at the fission site and hydrolyzes GTP to drive membrane ingression. Drp1 recruitment to the outer mitochondrial membrane (OMM) is a key regulatory event, which appears to require a pre-constriction step in which the endoplasmic reticulum (ER) and mitochondrion interact extensively, a process termed ERMD (ER-associated mitochondrial division). It is unclear how ER-mitochondrial …