Medical Biochemistry Commons^™

Pancreatic Cancer Cells Resistance To Gemcitabine: The Role Of Muc4 Mucin., S. Bafna, Sukhwinder Kaur, N. Momi, Surinder K. Batra

Journal Articles: Biochemistry & Molecular Biology

BACKGROUND: A major obstacle to the successful management of pancreatic cancer is to acquire resistance to the existing chemotherapeutic agents. Resistance to gemcitabine, the standard first-line chemotherapeutic agent for advanced and metastatic pancreatic cancer, is mainly attributed to an altered apoptotic threshold in the pancreatic cancer. The MUC4 transmembrane glycoprotein is aberrantly overexpressed in the pancreatic cancer and recently, has been shown to increase pancreatic tumour cell growth by the inhibition of apoptosis.

METHODS: Effect of MUC4 on pancreatic cancer cells resistance to gemcitabine was studied in MUC4-expressing and MUC4-knocked down pancreatic cancer cell lines after treatment with gemcitabine by …

Jnk1-Dependent Puma Expression Contributes To Hepatocyte Lipoapoptosis., Sophie C. Cazanave, Justin L. Mott, Nafisa A. Elmi, Steven F. Bronk, Nathan W. Werneburg, Yuko Akazawa, Alisan Kahraman, Sean P. Garrison, Gerard P. Zambetti, Michael R. Charlton, Gregory J. Gores

Journal Articles: Biochemistry & Molecular Biology

Free fatty acids (FFA) induce hepatocyte lipoapoptosis by a c-Jun N-terminal kinase (JNK)-dependent mechanism. However, the cellular processes by which JNK engages the core apoptotic machinery during lipotoxicity, especially activation of BH3-only proteins, remain incompletely understood. Thus, our aim was to determine whether JNK mediates induction of BH3-only proteins during hepatocyte lipoapoptosis. The saturated FFA palmitate, but not the monounsaturated FFA oleate, induces an increase in PUMA mRNA and protein levels. Palmitate induction of PUMA was JNK1-dependent in primary murine hepatocytes. Palmitate-mediated PUMA expression was inhibited by a dominant negative c-Jun, and direct binding of a phosphorylated c-Jun containing the …

The Human Rna Polymerase Ii-Associated Factor 1 (Hpaf1): A New Regulator Of Cell-Cycle Progression., Nicolas Moniaux, Christophe Nemos, Shonali Deb, Bing Zhu, Irena Dornreiter, Michael A. Hollingsworth, Surinder K. Batra

Journal Articles: Biochemistry & Molecular Biology

BACKGROUND: The human PAF (hPAF) complex is part of the RNA polymerase II transcription apparatus and regulates multiple steps in gene expression. Further, the yeast homolog of hPaf1 has a role in regulating the expression of a subset of genes involved in the cell-cycle. We therefore investigated the role of hPaf1 during progression of the cell-cycle.

METHODOLOGY/FINDINGS: Herein, we report that the expression of hPaf1, a subunit of the hPAF complex, increases with cell-cycle progression and is regulated in a cell-cycle dependant manner. hPaf1 specifically regulates a subclass of genes directly implicated in cell-cycle progression during G1/S, S/G2, and G2/M. …

Overexpression Of Mcl-1 Attenuates Liver Injury And Fibrosis In The Bile Duct-Ligated Mouse., Alisan Kahraman, Justin L. Mott, Steven F. Bronk, Nathan W. Werneburg, Fernando J. Barreyro, Maria E. Guicciardi, Yuko Akazawa, Karen Braley, Ruth W. Craig, Gregory J. Gores

Journal Articles: Biochemistry & Molecular Biology

Hepatocyte apoptosis contributes to liver injury and fibrosis after cholestatic injury. Our aim was to ascertain if the anti-apoptotic protein Mcl-1 alters liver injury or fibrosis in the bile duct-ligated mouse. Markers of apoptosis and fibrosis were compared in wild-type and transgenic mice expressing human Mcl-1 after bile duct ligation. Compared to hMcl-1 transgenic animals, ligated wild-type mice displayed a significant increase in TUNEL-positive cells and in caspase 3/7-positive hepatocytes. Consistent with apoptotic injury, the pro-apoptotic protein Bak underwent a conformational change to an activated form upon cholestatic injury, a change mitigated by hMcl-1 overexpression. Likewise, liver histology, number of …

Matrix Metalloproteinase Inhibitor, Cts-1027, Attenuates Liver Injury And Fibrosis In The Bile Duct-Ligated Mouse., Alisan Kahraman, Steven F. Bronk, Sophie Cazanave, Nathan W. Werneburg, Justin L. Mott, Patricia C. Contreras, Gregory J. Gores

Journal Articles: Biochemistry & Molecular Biology

Aim: Excessive matrix metalloproteinase (MMP) activity has been implicated in the pathogenesis of acute and chronic liver injury. CTS-1027 is an MMP inhibitor, which has previously been studied in humans as an anti-arthritic agent. Thus, our aim was to assess if CTS-1027 is hepato-protective and anti-fibrogenic during cholestatic liver injury. Methods: C57/BL6 mice were subjected to bile duct ligation (BDL) for 14 days. Either CTS-1027 or vehicle was administered by gavage. Results: BDL mice treated with CTS-1027 demonstrated a threefold reduction in hepatocyte apoptosis as assessed by the TUNEL assay or immunohistochemistry for caspase 3/7-positive cells as compared to vehicle-treated …

Micrornas Involved In Tumor Suppressor And Oncogene Pathways: Implications For Hepatobiliary Neoplasia., Justin L. Mott

Journal Articles: Biochemistry & Molecular Biology

MicroRNAs are a class of small regulatory RNAs that function to modulate protein expression. This control allows for fine-tuning of the cellular phenotype, including regulation of proliferation, cell signaling, and apoptosis; not surprisingly, microRNAs contribute to liver cancer biology. Recent investigations in human liver cancers and tumor-derived cell lines have demonstrated decreased or increased expression of particular microRNAs in hepatobiliary cancer cells. Based on predicted and validated protein targets as well as functional consequences of altered expression, microRNAs with decreased expression in liver tumor cells may normally aid in limiting neoplastic transformation. Conversely, selected microRNAs that are up-regulated in liver …

Death Receptor 5 Internalization Is Required For Lysosomal Permeabilization By Trail In Malignant Liver Cell Lines., Yuko Akazawa, Justin L. Mott, Steven F. Bronk, Nathan W. Werneburg, Alisan Kahraman, Maria Eugenia Guicciardi, Xue Wei Meng, Shigeru Kohno, Vijay H. Shah, Scott H. Kaufmann, Mark A. Mcniven, Gregory J. Gores

Journal Articles: Biochemistry & Molecular Biology

BACKGROUND & AIMS: Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) cytotoxicity in hepatocellular carcinoma cells is mediated by lysosomal permeabilization. Our aims were to determine which TRAIL receptor, death receptor (DR) 4 or DR5, mediates lysosomal permeabilization and assess whether receptor endocytosis followed by trafficking to lysosomes contributes in this process.

METHODS: TRAIL ligand internalization in Huh-7 cells was examined by confocal microscopy using Flag-tagged TRAIL, whereas DR4- and DR5-enhanced green fluorescent protein internalization was assessed by total internal reflection microscopy. Clathrin-dependent endocytosis was inhibited by expressing dominant negative dynamin.

RESULTS: Although Huh-7 cells express both TRAIL receptors, short hairpin RNA …

Revisiting Histidine-Dependent Acid Phosphatases: A Distinct Group Of Tyrosine Phosphatases., Suresh Veeramani, Ming-Shyue Lee, Ming-Fong Lin

Journal Articles: Biochemistry & Molecular Biology

Although classical protein tyrosine phosphatase (PTP) superfamily members are cysteine-dependent, emerging evidence shows that many acid phosphatases (AcPs) function as histidine-dependent PTPs in vivo. These AcPs dephosphorylate phospho-tyrosine substrates intracellularly and could have roles in development and disease. In contrast to cysteine-dependent PTPs, they utilize histidine, rather than cysteine, for substrate dephosphorylation. Structural analyses reveal that active site histidine, but not cysteine, faces towards the substrate and functions as the phosphate acceptor. Nonetheless, during dephosphorylation, both histidine-dependent and cysteine-dependent PTPs use their active site arginine and aspartate for substrate binding and proton donation, respectively. Thus, we propose that they should …

Genome Based Cell Population Heterogeneity Promotes Tumorigenicity: The Evolutionary Mechanism Of Cancer., Christine J. Ye, Joshua B. Stevens, Guo Liu, Steven W. Bremer, Aruna S. Jaiswal, Karen J. Ye, Ming-Fong Lin, Lesley Lawrenson, Wayne D. Lancaster, Markku Kurkinen, Joshua D. Liao, C. Gary Gairola, Malathy P. V. Shekhar, Satya Narayan, Fred R. Miller, Henry H. Q. Heng

Journal Articles: Biochemistry & Molecular Biology

Cancer progression represents an evolutionary process where overall genome level changes reflect system instability and serve as a driving force for evolving new systems. To illustrate this principle it must be demonstrated that karyotypic heterogeneity (population diversity) directly contributes to tumorigenicity. Five well characterized in vitro tumor progression models representing various types of cancers were selected for such an analysis. The tumorigenicity of each model has been linked to different molecular pathways, and there is no common molecular mechanism shared among them. According to our hypothesis that genome level heterogeneity is a key to cancer evolution, we expect to reveal …

Upregulation Of Pip3-Dependent Rac Exchanger 1 (P-Rex1) Promotes Prostate Cancer Metastasis., Jianbing Qin, Yan Xie, Bo Wang, Mikio Hoshino, Dennis W. Wolff, Jing Zhao, Margaret A. Scofield, Frank J. Dowd, Ming-Fong Lin, Yaping Tu

Journal Articles: Biochemistry & Molecular Biology

Excessive activation of G-protein-coupled receptor (GPCR) and receptor tyrosine kinase (RTK) pathways has been linked to prostate cancer metastasis. Rac activation by guanine nucleotide exchange factors (GEFs) plays an important role in directional cell migration, a critical step of tumor metastasis cascades. We found that the upregulation of P-Rex1, a Rac-selective GEF synergistically activated by Gbetagamma freed during GPCR signaling, and PIP3, generated during either RTK or GPCR signaling, strongly correlates with metastatic phenotypes in both prostate cancer cell lines and human prostate cancer specimens. Silencing endogenous P-Rex1 in metastatic prostate cancer PC-3 cells selectively inhibited Rac activity and reduced …

Micrornas: Key Modulators Of Posttranscriptional Gene Expression., Steven P. O'Hara, Justin L. Mott, Patrick L. Splinter, Gregory J. Gores, Nicholas F. Larusso

Journal Articles: Biochemistry & Molecular Biology

No abstract provided.

Elevated Expression Of L-Selectin Ligand In Lymph Node-Derived Human Prostate Cancer Cells Correlates With Increased Tumorigenicity., Prakash Radhakrishnan, Ming-Fong Lin, Pi-Wan Cheng

Journal Articles: Biochemistry & Molecular Biology

Human prostate cancer LNCaP cells including C-33 and C-81 cells were originally derived from the lymph nodes of a patient with metastatic prostate cancer. These two cells were employed for characterization of L-selectin ligand and in vitro tumorigenicity, because they mimic the clinical conditions of early and late-stage human prostate cancer. C-81 cells exhibit higher in vitro migratory and invasive properties as compared with C-33 cells. We find that the L-selectin ligand and mucin glycan-associated MECA-79 epitope were elevated in C-81 cells. An increase of these glycotopes positively correlates with elevated tumorigenicity and expression of key glycosyl- and sulfotransferase genes. …

Androgen-Independent Prostate Cancer Cells Acquire The Complete Steroidogenic Potential Of Synthesizing Testosterone From Cholesterol., Paulette R. Dillard, Ming-Fong Lin, Shafiq A. Khan

Journal Articles: Biochemistry & Molecular Biology

The proliferation and differentiation of normal prostate epithelial cells depends upon the action of androgens produced by the testis. Prostate cancers retain the ability to respond to androgens in the initial stages of cancer development, but progressively become independent of exogenous androgens in advanced stages of the disease while maintaining the expression of functional androgen receptor (AR). In the present study, we have determined the potential of prostate cancer cells to synthesize androgens from cholesterol which may be involved in intracrine regulation of AR in advanced stages of the disease. Established androgen-independent prostate cancer cell lines, PC3 and DU145 cells, …

Ovarian Cancer: Emerging Concept On Cancer Stem Cells., Moorthy P. Ponnusamy, Surinder K. Batra

Journal Articles: Biochemistry & Molecular Biology

Emerging evidence suggests that the capacity of a tumor to grow and propagate is dependent on a small subset of cells within a tumor, termed cancer stem cells. In fact, cancer cells, like stem cells, can proliferate indefinitely through a dysregulated cellular self-renewal capacity. Cancer stem cells may originate due to the distribution into self-renewal and differentiation pathways occurring in multi-potential stem cells, tissue-specific stem cells, progenitor cells and cancer cells. Recent studies have shown that ovarian cancer also contains stem cells or tumor-initiating cells. Moreover, ovarian serous adenocarcinomas were disaggregated and subjected to growth conditions to select for self-renewing, …

Deregulation Of Muc4 In Gastric Adenocarcinoma: Potential Pathobiological Implication In Poorly Differentiated Non-Signet Ring Cell Type Gastric Cancer., S. Senapati, P. Chaturvedi, P. Sharma, G Venkatraman, Jane L. Meza, W. El-Rifai, H. K. Roy, Surinder K. Batra

Journal Articles: Biochemistry & Molecular Biology

MUC4 is a large, heavily glycosylated transmembrane mucin, that is implicated in the pathogenesis of various types of cancers. To date, no extensive study has been done to check the expression and functional significance of MUC4 in different types of gastric adenocarcinomas. Here, we report the expression profile of MUC4 in gastric adenocarcinomas and its function in poorly differentiated gastric non-signet ring cell carcinoma (non-SRCC) type cells. Immunohistochemical analysis using tissue microarray (TMA) showed a significant difference in MUC4 expression between normal adjacent (n = 45) and gastric adenocarcinoma (n = 83; P < 0.001). MUC4 expression was not associated with tumour type, stage or with the degree of differentiation. To gain further insight into the significance of MUC4 expression in gastric non-SRCC cells, MUC4 was ectopically expressed in AGS, a poorly differentiated gastric non-signet ring cell line. The MUC4 overexpressing cells (AGS-MUC4) showed a significant increase (P < 0.005) in cell motility and a decrease in cellular aggregation as compared with the vector-transfected cells. Furthermore, in vivo tumorigenicity analysis revealed that animals transplanted with the MUC4 overexpressing cells (AGS-MUC4) had a greater incidence of tumours (83%) in comparison to empty vector control (17%). In addition, the expression of MUC4 resulted in enhanced expression of total cellular ErbB2 and phosphorylated ErbB2. In conclusion, our results showed that MUC4 is overexpressed in gastric adenocarcinoma tissues, and that it has a role in promoting aggressive properties in poorly differentiated gastric non-SRCC cells through the activation of the ErbB2 oncoprotein.

Mitochondrial Redox Signaling By P66shc Is Involved In Regulating Androgenic Growth Stimulation Of Human Prostate Cancer Cells., Suresh Veeramani, Ta-Chun Yuan, Fen-Fen Lin, Ming-Fong Lin

Journal Articles: Biochemistry & Molecular Biology

p66Shc is shown to negatively regulate the life span in mice through reactive oxygen species (ROS) production. Recent reports, however, revealed that p66Shc protein level is significantly elevated in several human cancer tissues and growth-stimulated carcinoma cells, suggesting a mitogenic and carcinogenic role for p66Shc. In this communication, we demonstrate for the first time that p66Shc mediates androgenic growth signals in androgen-sensitive human prostate cancer cells through mitochondrial ROS production. Growth stimulation of prostate cancer cells with 5alpha-dihydrotestosterone (DHT) is accompanied by increased p66Shc level and ROS production, which is abolished by antioxidant treatments. However, antioxidant treatments do not affect …

Muc4 Activates Her2 Signalling And Enhances The Motility Of Human Ovarian Cancer Cells., Moorthy P. Ponnusamy, A. P. Singh, Maneesh Jain, S. Chakraborty, N. Moniaux, Surinder K. Batra

Journal Articles: Biochemistry & Molecular Biology

The mucin MUC4 is a high molecular weight transmembrane glycoprotein. It consists of a mucin-type subunit (MUC4alpha) and a transmembrane growth factor-like subunit (MUC4beta). The mucin MUC4 is overexpressed in many epithelial malignancies including ovarian cancer, suggesting a possible role in the pathogenesis of these cancers. In this study, we investigated the functional role of MUC4 in the human ovarian cancer cell line SKOV3. The mucin MUC4 was ectopically expressed by stable transfection, and its expression was examined by western blot and confocal microscopy analyses. The in vitro studies demonstrated an enhanced motility of MUC4-expressing SKOV3 cells compared with the …

Bh3-Only Protein Mimetic Obatoclax Sensitizes Cholangiocarcinoma Cells To Apo2l/Trail-Induced Apoptosis., Justin L. Mott, Steve F. Bronk, Ruben A. Mesa, Scott H. Kaufmann, Gregory J. Gores

Journal Articles: Biochemistry & Molecular Biology

Human cholangiocarcinomas evade apoptosis by overexpression of Mcl-1. The drug obatoclax (GX15-070) inhibits antiapoptotic members of the Bcl-2 family including Mcl-1. The purpose of this study is to determine if obatoclax sensitizes human cholangiocarcinoma cells to apoptosis. The human cholangiocarcinoma cell lines, KMCH, KMBC, and TFK, were employed for these studies. Protein expression was assessed by immunoblot and protein-protein interactions detected by coprecipitation of the polypeptide of interest with S-tagged Mcl-1. Activation of Bak and Bax was observed by immunocytochemistry with conformation-specific antisera. Obatoclax induced minimal apoptosis alone; however, it increased apoptosis 3- to 13-fold in all three cancer cell …

Muc4 And Muc5ac Are Highly Specific Tumour-Associated Mucins In Biliary Tract Cancer., W. R. Matull, F. Andreola, A. Loh, Z. Adiguzel, M. Deheragoda, U. Qureshi, Surinder K. Batra, D. M. Swallow, S. P. Pereira

Journal Articles: Biochemistry & Molecular Biology

Alterations in epithelial mucin expression are associated with carcinogenesis, but there are few data in biliary tract cancer (BTC). In pancreatic malignancy, MUC4 is a diagnostic and prognostic tumour marker, whereas MUC5AC has been proposed as a sensitive serological marker for BTC. We assessed MUC4 and MUC5AC expression in (i) prospectively collected bile and serum specimens from 72 patients with biliary obstruction (39 BTC) by real-time reverse transcriptase-PCR (qPCR) and western blot analysis, and (ii) 79 archived biliary tissues (69 BTC) by immunohistochemistry. In bile, MUC4 protein was detected in 27% of BTC and 29% of primary sclerosing cholangitis (PSC) …

Early Diagnosis Of Pancreatic Cancer: Neutrophil Gelatinase-Associated Lipocalin As A Marker Of Pancreatic Intraepithelial Neoplasia., N. Moniaux, S. Chakraborty, M. Yalniz, J. Gonzalez, Valerie K. Shostrom, J. Standop, Subodh M. Lele, Michel M. Ouellette, Parviz M. Pour, Aaron Sasson, R. E. Brand, Michael A. Hollingsworth, Maneesh Jain, Surinder K. Batra

Journal Articles: Biochemistry & Molecular Biology

Pancreatic cancer is a highly lethal malignancy with a dismal 5-year survival of less than 5%. The scarcity of early biomarkers has considerably hindered our ability to launch preventive measures for this malignancy in a timely manner. Neutrophil gelatinase-associated lipocalin (NGAL), a 24-kDa glycoprotein, was reported to be upregulated nearly 27-fold in pancreatic cancer cells compared to normal ductal cells in a microarray analysis. Given the need for biomarkers in the early diagnosis of pancreatic cancer, we investigated the expression of NGAL in tissues with the objective of examining if NGAL immunostaining could be used to identify foci of pancreatic …

Trail Mediates Liver Injury By The Innate Immune System In The Bile Duct-Ligated Mouse., Alisan Kahraman, Fernando J. Barreyro, Steven F. Bronk, Nathan W. Werneburg, Justin L. Mott, Yuko Akazawa, Howard C Masuoka, Charles L Howe, Gregory J. Gores

Journal Articles: Biochemistry & Molecular Biology

The contribution of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), a death ligand expressed by cells of the innate immune system, to cholestatic liver injury has not been explored. Our aim was to ascertain if TRAIL contributes to liver injury in the bile duct-ligated (BDL) mouse. C57/BL6 wild-type (wt), TRAIL heterozygote (TRAIL(+/-)), and TRAIL knockout (TRAIL(-/-)) mice were used for these studies. Liver injury and fibrosis were examined 7 and 14 days after BDL, respectively. Hepatic TRAIL messenger RNA (mRNA) was 6-fold greater in BDL animals versus sham-operated wt animals (P < 0.01). The increased hepatic TRAIL expression was accompanied by an increase in liver accumulation of natural killer 1.1 (NK 1.1)-positive NK and natural killer T (NKT) cells, the predominant cell types expressing TRAIL. Depletion of NK 1.1-positive cells reduced hepatic TRAIL mRNA expression and serum alanine aminotransferase (ALT) values. Consistent with a role for NK/NKT cells in this model of liver injury, stress ligands necessary for their recognition of target cells were also up-regulated in hepatocytes following BDL. Compared to sham-operated wt mice, BDL mice displayed a 13-fold increase in terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) and an 11-fold increase in caspase 3/7-positive hepatocytes (P < 0.01). The number of TUNEL and caspase 3/7-positive cells was reduced by >80% in BDL TRAIL knockout animals (P < 0.05). Likewise, liver histology, number of bile infarcts, serum ALT values, hepatic fibrosis, and animal survival were also improved in BDL TRAIL(-/-) animals as compared to wt animals. Conclusion: These observations support a pivotal role for TRAIL in cholestatic liver injury mediated by NK 1.1-positive NK/NKT cells.

Genome-Wide Expression Profiling Reveals Transcriptomic Variation And Perturbed Gene Networks In Androgen-Dependent And Androgen-Independent Prostate Cancer Cells., Ajay P. Singh, Sangeeta Bafna, Kunal Chaudhary, Ganesh Venkatraman, Lynette Smith, James D. Eudy, Sonny L. Johansson, Ming-Fong Lin, Surinder K. Batra

Journal Articles: Biochemistry & Molecular Biology

Previously, we have developed a unique in vitro LNCaP cell model, which includes androgen-dependent (LNCaP-C33), androgen-independent (LNCaP-C81) and an intermediate phenotype (LNCaP-C51) cell lines resembling the stages of prostate cancer progression to hormone independence. This model is advantageous in overcoming the heterogeneity associated with the prostate cancer up to a certain extent. We characterized and compared the gene expression profiles in LNCaP-C33 (androgen-dependent) and LNCaP-C81 (androgen-independent) cells using Affymetrix GeneChip array analyses. Multiple genes were identified exhibiting differential expression during androgen-independent progression. Among the important genes upregulated in androgen-independent cells were PCDH7, TPTE, TSPY, EPHA3, HGF, MET, EGF, TEM8, etc., …

Mir-29 Regulates Mcl-1 Protein Expression And Apoptosis., Justin L. Mott, Shogo Kobayashi, Steven F. Bronk, Gregory J. Gores

Journal Articles: Biochemistry & Molecular Biology

Cellular expression of Mcl-1, an anti-apoptotic Bcl-2 family member, is tightly regulated. Recently, Bcl-2 expression was shown to be regulated by microRNAs, small endogenous RNA molecules that regulate protein expression through sequence-specific interaction with messenger RNA. By analogy, we reasoned that Mcl-1 expression may also be regulated by microRNAs. We chose human immortalized, but non-malignant, H69 cholangiocyte and malignant KMCH cholangiocarcinoma cell lines for these studies, because Mcl-1 is dysregulated in cells with the malignant phenotype. By in silico analysis, we identified a putative target site in the Mcl-1 mRNA for the mir-29 family, and found that mir-29b was highly …

Recent Advances In Cancer Stem/Progenitor Cell Research: Therapeutic Implications For Overcoming Resistance To The Most Aggressive Cancers., M. Mimeault, Ralph Hauke, Parmender P. Mehta, Surinder K. Batra

Journal Articles: Biochemistry & Molecular Biology

Overcoming intrinsic and acquired resistance of cancer stem/progenitor cells to current clinical treatments represents a major challenge in treating and curing the most aggressive and metastatic cancers. This review summarizes recent advances in our understanding of the cellular origin and molecular mechanisms at the basis of cancer initiation and progression as well as the heterogeneity of cancers arising from the malignant transformation of adult stem/progenitor cells. We describe the critical functions provided by several growth factor cascades, including epidermal growth factor receptor (EGFR), platelet-derived growth factor receptor (PDGFR), stem cell factor (SCF) receptor (KIT), hedgehog and Wnt/beta-catenin signalling pathways that …

Human Muc4 Mucin Induces Ultra-Structural Changes And Tumorigenicity In Pancreatic Cancer Cells., N. Moniaux, P. Chaturvedi, G. C. Varshney, Jane L. Meza, J. F. Rodriguez-Sierra, J-P Aubert, Surinder K. Batra

Journal Articles: Biochemistry & Molecular Biology

MUC4 is a type-1 transmembrane glycoprotein and is overexpressed in many carcinomas. It is a heterodimeric protein of 930 kDa, composed of a mucin-type subunit, MUC4alpha, and a membrane-bound growth factor-like subunit, MUC4beta. MUC4 mRNA contains unique 5' and 3' coding sequences along with a large variable number of tandem repeat (VNTR) domain of 7-19 kb. A direct association of MUC4 overexpression has been established with the degree of invasiveness and poor prognosis of pancreatic cancer. To understand the precise role of MUC4 in pancreatic cancer, we engineered a MUC4 complementary DNA construct, mini-MUC4, whose deduced protein (320 kDa) is …

The Notch Regulator Maml1 Interacts With P53 And Functions As A Coactivator., Yongtong Zhao, Rebecca B. Katzman, Laurie M. Delmolino, Ishfaq Bhat, Ying Zhang, Channabasavaiah B. Gurumurthy, Aleksandra Germaniuk-Kurowska, Honey V. Reddi, Aharon Solomon, Mu-Sheng Zeng, Aisha Kung, Hui Ma, Qingshen Gao, Goberdhan Dimri, Adina Stanculescu, Lucio Miele, Lizi Wu, James D. Griffin, David E. Wazer, Hamid Band, Vimla Band

Journal Articles: Biochemistry & Molecular Biology

Members of the evolutionarily conserved Mastermind (MAM) protein family, including the three related mammalian Mastermind-like (MAML) proteins MAML1-3, function as crucial coactivators of Notch-mediated transcriptional activation. Given the recent evidence of cross-talk between the p53 and Notch signal transduction pathways, we have investigated whether MAML1 may also be a transcriptional coactivator of p53. Indeed, we show here that MAML1 is able to interact with p53. We show that MAML1-p53 interaction involves the N-terminal region of MAML1 and the DNA-binding domain of p53, and we use a chromatin immunoprecipitation assay to show that MAML1 is part of the activator complex that …

An Essential Role Of Human Ada3 In P53 Acetylation., Alo Nag, Aleksandra Germaniuk-Kurowska, Manjari Dimri, Michael A. Sassack, Channabasavaiah B. Gurumurthy, Qingshen Gao, Goberdhan Dimri, Hamid Band, Vimla Band

Journal Articles: Biochemistry & Molecular Biology

The p53 tumor suppressor protein functions as a critical component of genotoxic stress response by regulating the expression of effector gene products that control the fate of a cell following DNA damage. Unstressed cells maintain p53 at low levels through regulated degradation, and p53 levels and activity are rapidly elevated upon genotoxic stress. Biochemical mechanisms that control the levels and activity of p53 are therefore of great interest. We and others have recently identified hAda3 (human homologue of yeast alteration/deficiency in activation 3) as a p53-interacting protein and enhancer of p53 activity. Here, we show that endogenous levels of p53 …

Sustained Il-6/Stat-3 Signaling In Cholangiocarcinoma Cells Due To Socs-3 Epigenetic Silencing., Hajime Isomoto, Justin L. Mott, Shogo Kobayashi, Nathan W. Werneburg, Steve F. Bronk, Serge Haan, Gregory J. Gores

Journal Articles: Biochemistry & Molecular Biology

BACKGROUND & AIMS: Interleukin 6 (IL-6)-mediated signal transducers and activators of transcription 3 (STAT-3) phosphorylation (activation) is aberrantly sustained in cholangiocarcinoma cells resulting in enhanced myeloid cell leukemia 1 (Mcl-1) expression and resistance to apoptosis. Because suppressor of cytokine signaling 3 (SOCS) controls the IL-6/STAT-3 signaling pathway by a classic feedback loop, the aims of this study were to examine SOCS-3 regulation in human cholangiocarcinoma.

METHODS: SOCS-3 expression was assessed in human cholangiocarcinoma tissue and the Mz-ChA-1 and CCLP1 human cholangiocarcinoma cell lines.

RESULTS: An inverse correlation was observed between phospho-STAT-3 and SOCS-3 protein expression in cholangiocarcinoma. In those cancers …

Androgen-Regulated Formation And Degradation Of Gap Junctions In Androgen-Responsive Human Prostate Cancer Cells., Shalini Mitra, Lakshmanan Annamalai, Souvik Chakraborty, Kristen E. Johnson, Xiao-Hong Song, Surinder K. Batra, Parmender P. Mehta

Journal Articles: Biochemistry & Molecular Biology

The constituent proteins of gap junctions, called connexins (Cxs), have a short half-life. Despite this, the physiological stimuli that control the assembly of Cxs into gap junctions and their degradation have remained poorly understood. We show here that in androgen-responsive human prostate cancer cells, androgens control the expression level of Cx32-and hence the extent of gap junction formation-post-translationally. In the absence of androgens, a major fraction of Cx32 is degraded presumably by endoplasmic reticulum-associated degradation, whereas in their presence, this fraction is rescued from degradation. We also show that Cx32 and Cx43 degrade by a similar mechanism. Thus, androgens regulate …

The Human Paf Complex Coordinates Transcription With Events Downstream Of Rna Synthesis., Bing Zhu, Subhrangsu S. Mandal, Anh-Dung Pham, Yong Zheng, Hediye Erdjument-Bromage, Surinder K. Batra, Paul Tempst, Danny Reinberg

Journal Articles: Biochemistry & Molecular Biology

The yeast PAF (yPAF) complex interacts with RNA polymerase II and coordinates the setting of histone marks associated with active transcription. We report the isolation and functional characterization of the human PAF (hPAF) complex. hPAF shares four subunits with yPAF (hCtr9, hPaf1, hLeo1, and hCdc73), but contains a novel higher eukaryotic-specific subunit, hSki8. RNAi against hSki8 or hCtr9 reduces the cellular levels of other hPAF subunits and of mono- and trimethylated H3-Lys 4 and dimethylated H3-Lys 79. The hSki8 subunit is also a component of the human SKI (hSKI) complex. Yeast SKI complex is cytoplasmic and together with Exosome mediates …