ABSTRACT
UNLABELLED: We studied the effects of isoflavones and irradiation on cell cycle in a human salivary gland cell line (HSG). Genistein and a soy isoflavone conjugate (NS) inhibited DNA synthesis. Cells deconjugated the glucoside form of isoflavones in NS to the aglycones genistein and daidzein. NS, genistein and IR increased phosphorylation of p53 and p21 CIP1 at serine 15 (phos-p53). Irradiation and NS also increased levels of p21 CIP1. In a cologenic survival assay, cells in log phase growth had high radio-sensitivity with 2 Gy causing a reduction in survival (SF2=0.45). CONCLUSION: isoflavones and radiation may interact to sensitize cancer cells to radiation.
Subject(s)
Gamma Rays , Genistein/pharmacology , Glycine max/chemistry , Isoflavones/pharmacology , Salivary Glands/drug effects , Cell Cycle/drug effects , Cell Line , Cell Proliferation/drug effects , Cell Survival/drug effects , Cell Survival/radiation effects , Cyclin-Dependent Kinase Inhibitor p21/analysis , Cyclin-Dependent Kinase Inhibitor p27 , DNA Damage , Dose-Response Relationship, Drug , Humans , Intracellular Signaling Peptides and Proteins/analysis , Phosphorylation , Salivary Glands/cytology , Salivary Glands/radiation effects , Tumor Suppressor Protein p53/analysis , Vitamin E/pharmacologyABSTRACT
Conditioned medium from gestation day 18 rat placental cultures showed potent stimulation of the directional migration of human retinal endothelial cells. To examine the role of major secreted placental proteins in this chemotaxic activity, prolactin-like proteins (PLPs)-B and C were purified from rat placenta using immuno-affinity chromatography. In contrast to conditioned medium, native PLP-B and PLP-C preparations failed to show any significant stimulation of endothelial cell migration. This study further examined the ability of PLP-B to bind to rat receptors for growth hormone (GH-R) and prolactin (PRL-R). In competitive binding assays with [125I]-hGH, neither native nor recombinant PLP-B preparations showed significant high affinity binding to the transfected rat GH-R or PRL-R. In summary, neither PLP-B nor PLP-C exhibit the potent chemotaxis stimulatory activity of placental conditioned media, nor does PLP-B show evidence of ability to act via rat GH or PRL receptors.
