title: Sodium butyrate modulates p53 and Bcl-2 expression in human retinoblastoma cell lines.
abstract: Sodium butyrate (SB) is a potent biological modifier that can induce diverse effects including growth inhibition, differentiation, or apoptosis of many cell types including retinoblastoma (Rb), and modulation of genes such as c-fos and p53. In this study we assessed the effects of SB on cell growth and expression of p53, critical for cell cycle control, and Bcl-2, an inhibitor of apoptosis, in two human Rb cell lines (Y79 and WERI-Rb1). Attachment cultures were treated with 1 mM SB for up to 5 days and immunocytochemistry was used to examine for the expression of neural cell adhesion molecule (NCAM), p53, and Bcl-2. Suspension cultures of both cell lines were also treated with 1 and 4 mM SB, and at selected times cell extracts were prepared and the expression of p53 and Bcl-2 proteins determined by Western blot analysis. Treatment with 1 mM SB of both cell lines for 5 days inhibited growth and induced morphological changes including extension of neurite-like processes. Up to 12 h after 1 mM SB treatment, p53 and Bcl-2 expressions were similar to control levels, then gradually decreased to very low levels at 5 days. SB (4 mM) also inhibited growth associated with cell death, which was apparent at 24 h posttreatment. Expressions of p53 and Bcl-2 were decreased below control levels at 4 h, and by 24 h only very low levels of protein were detected. SB-induced modulation of p53 and Bcl-2 expression may have implications for controlling Rb growth, particularly in combination with chemotherapy drugs, which are increasingly used in the treatment of Rb.
authors.affiliation: Department of Clinical Ophthalmology, University of Sydney, NSW, Australia. michele@eye.usyd.edu.au
authors.forename: M C
authors.initials: MC
authors.lastname: Madigan
authors.forename: G
authors.initials: G
authors.lastname: Chaudhri
authors.forename: P L
authors.initials: PL
authors.lastname: Penfold
authors.forename: R M
authors.initials: RM
authors.lastname: Conway
mesh_terms: D002087:Butyrates / Q000494:pharmacology* / Q000627:therapeutic use; D015870:Gene Expression / Q000187:drug effects; D016161:Genes, Retinoblastoma / Q000502:physiology; D019254:Genes, bcl-2 / Q000187:drug effects* / Q000502:physiology; D016158:Genes, p53 / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D019572:Retinal Neoplasms / Q000188:drug therapy / Q000235:genetics* / Q000378:metabolism; D012175:Retinoblastoma / Q000188:drug therapy / Q000378:metabolism*; D014407:Tumor Cells, Cultured / Q000187:drug effects; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
chemical_list: D002087:Butyrates; D019253:Proto-Oncogene Proteins c-bcl-2; D016159:Tumor Suppressor Protein p53