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Receptor Heterodimers (receptor + heterodimer)
Selected AbstractsCharacterization of the RSL1-dependent conditional expression system in LNCaP prostate cancer cells and development of a single vector formatTHE PROSTATE, Issue 8 2007Julie Lessard Abstract Background Conditional expression systems are useful tools for the study of gene function but the use of these systems in prostate cancer cells is limited by the undesired biological effects of the inducing ligands. The RheoSwitch system employs RheoSwitch Ligand 1 (RSL1), a non-steroidal analog of the insect hormone ecdysone, to activate a modified nuclear receptor heterodimer that controls target gene expression via GAL4 response elements. This system has not been tested in prostate cancer cells. Methods We established LNCaP human prostate cancer cell lines that constitutively express RheoSwitch transcription factors to quantify RSL1-dependent expression and assess the effects of RSL1 on cell proliferation and endogenous gene expression. Potential RSL1-responsive genes were identified using Affymetrix microarrays and validated by Northern blot hybridization. A single-vector format was developed to establish cell lines that conditionally produce a recombinant protein. Results Stable cell lines displayed tight and potent (over several orders of magnitude) RSL1-dependent regulation of a transiently transfected luciferase reporter gene. RSL1 did not affect basal or androgen-stimulated cell proliferation and exerted minimal effects on the expression of endogenous genes. Cell lines established using the single-vector system also displayed strictly RSL1-dependent production of the recombinant protein encoded by the stably integrated RSL1-responsive expression cassette. Conclusions The RheoSwitch system is well suited for conditional gene expression in prostate cancer cells. The single-vector format should facilitate the production of stable cell lines. This system should be useful for the study of proteins involved in prostate cancer in both cell and animal models of the disease. Prostate 67: 808,819, 2007. © 2007 Wiley-Liss, Inc. [source] PPAR gamma activators induce differentiation of B12 oligodendrocyte-like cells and rat spinal cord oligodendrocytesJOURNAL OF NEUROCHEMISTRY, Issue 2002A. D. Roth The regulation of CNS lipid metabolism by nuclear receptors and their relation to cell differentiation remains undetermined. Since myelinating oligodendrocytes are the major lipid-synthesizing cells in the CNS, we characterized the effect of PPAR activation in a CNS derived cell line that expresses oligodendrocyte markers and compared these effects with oligodendrocyte primary cultures (90,95% pure). The rat glioma derived B12 cell line express the three major PPAR isoforms (PPAR ,, , and ,) and present a large number of peroxisomes, indicating an important lipid metabolism. Treatment with ciprofibrate, a general PPAR activator and clinical hypolipidemic, induces proliferation arrest, process extension and a moderate rise in the expression of acyl-CoA oxidase, a specific marker of peroxisomal proliferation. Cell growth arrest by ciprofibrate is enhanced 100-fold by low concentrations of retinoic acid (0.01 ,m), suggesting the involvement of the PPAR-retinoid acid receptor heterodimers. Since ciprofibrate possibly acts by modifying the concentration of endogenous PPAR ligands, we traced its effects to PPAR, by using isoform specific ligands: Troglitazone and 15-deoxy-prostaglandin J2, both of which induce growth arrest and process extension in B12 cells. These effects were corroborated on rat spinal cord derived oligodendrocytes primary cultures, where a significant rise in the number of mature oligodendrocytes is observed in response to PPAR, activators. These results show that PPAR,, a master gene in the differentiation of adipose tissue could be involved in the lipid metabolism of maturing oligodendrocytes. [source] Frequent overexpression of multiple ErbB receptors by head and neck squamous cell carcinoma contrasts with rare antibody immunity in patientsTHE JOURNAL OF PATHOLOGY, Issue 3 2004Roberto Bei Abstract In an effort to elucidate the role of ErbB receptors in human head and neck squamous cell carcinoma (HNSCC), expression abnormalities and subcellular localization of epidermal growth factor receptor (EGFR), ErbB2, ErbB3, and ErbB4 were investigated along with EGF and tenascin by immunohistochemistry in 38 carcinomas as compared to adjacent normal mucosa of 24 cases. Although tumour-specific overexpression affected each ErbB receptor (EGFR 47%, ErbB2 29%, ErbB3 21%, ErbB4 26%), EGFR abnormalities were most prevalent. The latter, and overexpression of more than two ErbB receptors in the same tumour, which always included EGFR, correlated with metastatic disease. ErbB products were specifically detected on the cell membrane and in the cytoplasm. In contrast, ErbB4 was uniquely localized to the nucleus in 7 carcinomas and a tumour-derived cell line, indicating a role for regulated intramembrane proteolysis resulting in nuclear ErbB4 translocation in HNSCC. Expression of prototype ligand EGF or low-affinity stromal activator tenascin correlated significantly with EGFR overexpression, implying chronic EGFR activation. Simultaneous overexpression of additional ErbB receptors in most of these cases suggested recurrent involvement of receptor heterodimers. In spite of frequent ErbB receptor alterations, autologous ErbB serum antibodies were rare, with only 1 of 38 tumour patients exhibiting an ErbB2-specific immune response. Based on upregulation of several known immunosuppressive molecules, scarcity of ErbB-specific antibodies is consistent with attenuation of natural tumour-specific immune responses in HNSCC. Copyright © 2004 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. [source] Co-localization of multiple ErbB receptors in stratified epithelium of oral squamous cell carcinomaTHE JOURNAL OF PATHOLOGY, Issue 3 2001Roberto Bei Abstract The expression of all four ErbB receptors was compared by immunohistochemistry, using receptor-specific polyclonal antisera, in 32 invasive, 11 in situ carcinomas, six benign lesions, and 22 samples of histologically normal mucosa adjacent to specimens of carcinoma originating from oral cavity epithelium. Among invasive and in situ carcinoma, EGFR expression was the most prevalent (in 29/32 and 8/11 cases, respectively) followed by ErbB2 (17/32 and 2/11) and ErbB4 (9/32 and 1/10), while ErbB3 was only detected in invasive tumours (12/32). Specific patterns included invasive tumours with expression of EGFR (8/32) or ErbB4 (1/32) alone, as well as different receptor combinations (EGFR+ErbB2, EGFR+ErbB4, EGFR+ErbB2+ErbB3, EGFR+ErbB2+ErbB4, and all four receptors). Simultaneous expression of three or four ErbB receptors correlated with tumour invasion (p=2.2×10,4) and localized in the intermediate epithelial cell layer of well and moderately differentiated tumours. No other significant correlation with clinico-pathological features was noticed. Some benign lesions and histologically normal mucosa adjacent to carcinomas showed weak immunostaining of EGFR (10/28), ErbB2 (4/28) or ErbB4 (3/28). By comparison, overexpression, as indicated by increased staining intensity, was observed in invasive tumours for EGFR (18/32), ErbB2 (8/32), ErbB4 (3/32), and ErbB3 (3/32). Statistical evaluation demonstrated a significant association of EGFR or ErbB2 overexpression with invasive carcinoma when compared with benign lesions and apparently normal epithelium (p=5.2×10,7 and p=5×10,3, respectively). Tumour-specific overexpression of ErbB receptors and their co-expression, most frequently involving EGFR and ErbB2, in the same cell layer of neoplastic epithelium, implicate receptor heterodimers in the pathogenesis of oral squamous carcinoma. Copyright © 2001 John Wiley & Sons, Ltd. [source] | ||||||||||