Project description:Purpose: Core 3 derived glycans, a major type of O-glycan expressed by normal epithelial cells of the gastrointestinal tract, are downregulated during malignancy, because of loss of expression of functional β3-N-acetylglucosaminyltransferase-6 (core 3 synthase). We investigated the expression of core 3 synthase in normal pancreas and pancreatic cancer and evaluated the biological effects of re-expressing core 3 synthase in pancreatic cancer cells that had lost expression. Experimental Design: We determined that pancreatic tumors and tumor cell lines have lost expression of core 3 synthase. We therefore re-expressed in human pancreatic cancer cells (Capan-2 and FG) to investigate the contribution of core 3 glycans to malignant progression. Results: Pancreatic cancer cells expressing core 3 synthase showed reduced in vitro cell proliferation, migration and invasion compared with vector control cells. Expression of core 3 O-glycans induced altered expression of β1 integrin, decreased activation of focal adhesion kinase, led to the down regulation of expression of several genes including REG1α and FGFR3, and altered lamellipodia formation. The addition of a GlcNAc residue by core 3 synthase leads to the extension of the tumor associated Tn structure on MUC1. Orthotopic injection of FG cells expressing core 3 synthase into the pancreas of nude mice produced significantly smaller tumors and decreased metastasis to the surrounding tissues compared to vector control FG cells. Conclusions: These findings indicate that expression of core 3 derived O-glycans in pancreatic cancer cells suppresses tumor growth and metastasis through modulation of glycosylation of mucins and other cell surface and extracellular matrix proteins. Two-condition experiment, Core 3 synthase stable expression (C3) vs. vector control (PLVX) cells. Biological replicates: 3 Core 3 synthase stable expression, 3 vector control, independently grown and harvested. One replicate per array.

Project description:Burkitt lymphoma (BL) can often be cured by intensive chemotherapy, but the toxicity of such therapy precludes its use in the elderly and in patients with endemic BL (eBL) in developing countries, necessitating new strategies. The normal germinal center B cell is the presumed cell of origin for both BL and diffuse large B cell lymphoma (DLBCL), yet gene expression analysis suggests that these malignancies may utilize different oncogenic pathways. BL is subdivided into a sporadic subtype (sBL) that is diagnosed in developed countries, the EBV-associated eBL subtype, and an HIV-associated subtype (hivBL), but it is unclear whether these subtypes employ similar or divergent oncogenic mechanisms. Here we used high throughput RNA sequencing and RNA interference screening to discover essential regulatory pathways that cooperate with MYC, the defining oncogene of this cancer. In 70% of sBL cases, mutations affecting the transcription factor TCF3 (E2A) or its negative regulator ID3 fostered TCF3 dependency. TCF3 activated the pro-survival PI(3) kinase pathway in BL, in part by augmenting tonic B cell receptor signaling. In 38% of sBL cases, oncogenic CCND3 mutations produced highly stable cyclin D3 isoforms that drive cell cycle progression. These findings suggest opportunities to improve therapy for patients with BL. Gene expression was analyzed using Agilent human 4X44K oligo gene expression arrays. Cell lines (Namalwa, BL41, Daudi, Defauw, and THOMAS) were infected with control (empty vector, Cy3) paired with ID3 (Cy5) or control (shControl, Cy3) paired with shTCF3 (Cy5) constructs, and changes in gene expression were monitored over time after induction of the constructs with doxycyclin. In Namalwa (n=8) and THOMAS (n=4) cell lines, a four timepoint series (24, 48, 72, 96 hours) of construct induction was analyzed, for a total of 12 arrays. In BL41 (n=4), Daudi (n=4) and Defauw (n=4) cell lines, a two timepoint series (24 and 48 hours) of construct induction was analyzed, for a total of 12 arrays. In addition, two cell lines (Daudi and THOMAS) were treated with Rapamycin (100 pM) and paired with a DMSO control in a four timepoint series (3, 6, 12 and 24 hours) for a total of 8 arrays.

Project description:Following androgen ablation treatment for advanced prostate cancer, almost all men relapse after a period of initial response to therapy, which eventually is life threatening. We have previously found that purine-rich element binding protein, PUR alpha, was significantly repressed in androgen-independent prostate cancer cell lines in comparison to an androgen-dependent line. Moreover, over-expressing PURa in androgen-independent prostate cancer cells attenuated their cell proliferation. The aim of the studies described here was to uncover some of the mechanisms by which over-expression of PURa attenuates cell proliferation. A set of common genes induced by over-expressing PURa both in PC3 and LNCaP cells was analyzed by DNA microarray. The results were then validated utilizing quantitative reverse transcription-PCR. Using a 5.3-kb region of the PSA promoter containing androgen response elements, the participation of PURa in androgen regulated gene expression was determined. Genes involved in stress response and cell differentiation were induced in cells over-expressing PURa. Some of the genes that are targets of androgen regulation are also induced. Most strikingly, ectopic expression of PURa induced transcriptional activity of the 5.3-kb PSA promoter containing androgen response elements, without androgen stimulation. Based upon the consideration that some of the genes involved in cell stress and differentiation are also regulated by androgens our data suggest that PURa shares some common pathway regulated by the androgen receptor. These findings suggest that regulation of PURa expression in prostate cancer cells may serve as a therapeutic target for hormone refractory prostate cancer. Experiment Overall Design: PC3 cells (low in PURa expression) was stably over-expressed PURa. Total RNA of the cells was collected simultaneously with that of PC3 transfected with mock vector. Experiment Overall Design: LNCaP cells (Express PURa more than PC3 cells) was PURa-over-expressed with retrovirus vector (MSCV-PIG) and selected with puromycin for 72hr. Total RNA of the cells was collected simultaneously with that of LNCaP cells infected with mock vector. Experiment Overall Design: One set of RNA derived from PC3 cells and two independent RNA derived from LNCaP cells retrovirus infection were used for DNA microarray. Quality and concentration of total RNA was verified using Agilent Bioanalyzer and Nanodrop Spectrophotometer, respectively. T7 oligo(dT) primer (Sigma-Proligo, Boulder, CO) and 5ug total RNA are combined for first strand cDNA synthesis. Following second strand cDNA synthesis and cDNA cleanup (Phase Lock Gel Light, Eppendorf, Hamburg, Germany) an in vitro transcription reaction was performed overnight using T7 RNA transcript labeling kit provided by Enzo Life Sciences, Inc. (Farmingdale, NY). IVT reactions were cleaned using RNeasy Mini Kit (Qiagen) and concentration determined by Nanodrop Spectrophotometer. 15ug cRNA was fragmented using 5X fragmentation buffer (made in-house). Hybridization cocktail was made in accordance with Affymetrix eukaryotic expression array protocol (Affymetrix, Santa Clara, CA) and combined with fragmented cRNA. 10ug cRNA was loaded onto Human U133Plus 2.0 genome arrays (Affymetrix, Santa Clara, CA) and hybridized overnight for 16 hours. After hybridization, staining and washing of the arrays was performed following the Affymetrix eukaryotic expression array protocol, including staining with streptavidin-phycoerythrin, antibody stain, and a second streptavidin-phycoerythrin stain. After washing and staining, all arrays were scanned with the Affymetrix GeneChip Scanner and data collected with GeneChip Operating System 1.4 (GCOS, Affymetrix, Santa Clara, CA). Experiment Overall Design: The quality of the microarray experiments was assessed with affyPLM and Affy, two Bioconductor packages for statistical analysis of microarray data. To estimate the gene expression signals, data analysis was conducted on the chipsâ CEL file probe signal values at the Affymetrix probe pair (perfect match (PM) probe and mismatch (MM) probe) level, using the statistical algorithm Robust Multiarray Analysis (RMA) expression measure (Irizarry RA et al. 2003) with Affy. This probe level data processing includes a normalization procedure utilizing the quantile normalization method (Bolstad BM et al. 2003) to reduce the obscuring variation between microarrays, which might be introduced during the processes of sample preparation, manufacture, fluorescence labeling, hybridization and/or scanning. Exploratory data analysis (EDA) was performed with the preprocessed data above. Between-treatment and between-replicate variations were examined with the pair-wise MvA plots, in which the base 2 log ratios (M) between two samples are plotted against their averaged base 2 log signals (A). With the signal estimates, Principal Component analysis (PCA) was also performed to assess sample variability. Experiment Overall Design: With the signal intensities obtained above, an empirical Bayes method with the Gamma-Gamma modeling, as implemented in the bioconductor package EBarrays, was used to estimate the posterior probabilities of the differential expression of genes between PURA and Vector only sample conditions (Newton MA et al. 2001, Kendziorski Cm et al. 2003, Newton MA et al. 2004). The criterion of the posterior probability > 0.5, which means the posterior odds favoring change, was used to produce the differentially expressed gene list. Experiment Overall Design: All Bioconductor packages are available at http://www.bioconductor.org and all computation was performed under R environment (http://www.r-project.org).

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