title: Down regulation of CSL activity inhibits cell proliferation in prostate and breast cancer cells.
abstract: The Notch receptor pathway provides a paradigm for juxtacrine signaling pathways and controls stem cell function, developmental cell fate decisions, and cellular differentiation. The Notch pathway is constitutively activated in human cancers by chromosomal rearrangements, activating point mutations, or altered expression patterns. Therefore, the Notch pathway is the subject of chemotherapeutic intervention in a variety of human cancers. Notch receptor activation results in the gamma-secretase dependent proteolytic cleavage of the receptor to liberate the Notch intracellular domain that acts to mediate co-activator recruitment to the DNA binding transcription factor, CSL (CBF-1/RBP-Jκ, Su(H), Lag-1). Therapeutic targeting of the Notch pathway by gamma-secretase inhibitors prevents NICD production and regulates CSL-dependent transcriptional activity. To interrogate the loss of CSL activity in breast and prostate cancer cells, we used lentiviral-based shRNA knockdown of CSL. Knockdown of CSL expression was assessed by decreased DNA binding activity and resulted in decreased cell proliferation. In contrast, gamma-secretase inhibitor (GSI) treatment of these prostate and breast cancer cell lines resulted in minimal growth effects. PCR profiling of Notch pathway genes identified expression changes in few genes (Delta-like-1, Deltex-1, LMO2, and SH2D1A) after CSL knockdown. Consistent with differential effects of GSI on cell survival, GSI treatment failed to recapitulate the gene expression changes observed after CSL knockdown. Thus, CSL inhibition may provide a more effective mechanism to inhibit Notch-pathway dependent cancer cell proliferation as compared to GSI treatment.
authors.affiliation: Department of Medicine, Feist-Weiller Cancer Center, Louisiana State University Health Sciences Center-Shreveport, Shreveport, Louisiana 71130, USA.
authors.forename: Thomas
authors.initials: T
authors.lastname: Yong
authors.forename: Amanda
authors.initials: A
authors.lastname: Sun
authors.forename: Michael D
authors.initials: MD
authors.lastname: Henry
authors.forename: Shari
authors.initials: S
authors.lastname: Meyers
authors.forename: J Nathan
authors.initials: JN
authors.lastname: Davis
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D001943:Breast Neoplasms; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D015536:Down-Regulation / Q000235:genetics*; D005260:Female; D020869:Gene Expression Profiling; D055785:Gene Knockdown Techniques; D006801:Humans; D051819:Immunoglobulin J Recombination Signal Sequence-Binding Protein / Q000235:genetics / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics; D060588:LIM Domain Proteins / Q000235:genetics; D008297:Male; D051379:Mice; D009842:Oligopeptides / Q000494:pharmacology; D011471:Prostatic Neoplasms; D011518:Proto-Oncogene Proteins / Q000235:genetics; D034622:RNA Interference; D051880:Receptors, Notch / Q000378:metabolism*; D012045:Regulatory Sequences, Nucleic Acid; D015398:Signal Transduction / Q000235:genetics; D000071179:Signaling Lymphocytic Activation Molecule Associated Protein
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000970:Antineoplastic Agents; D051819:Immunoglobulin J Recombination Signal Sequence-Binding Protein; D047908:Intracellular Signaling Peptides and Proteins; D060588:LIM Domain Proteins; C085117:LMO2 protein, human; D009842:Oligopeptides; D011518:Proto-Oncogene Proteins; C497570:RBPJ protein, human; D051880:Receptors, Notch; C114953:SH2D1A protein, human; D000071179:Signaling Lymphocytic Activation Molecule Associated Protein; C523462:benzyloxycarbonyl-leucyl-leucyl-norleucinal