ABSTRACT
Elevated parathyroid hormone-related protein (PTHrP) is responsible for humoral hypercalcemia of malignancy (HHM), which is of clinical significance in treatment of terminal patients with malignancies. Steroid hormones were known to cause suppression of PTHrP expression. However, detailed studies linking multiple steroid hormones to PTHrP expression are lacking. Here we studied PTHrP expression in response to steroid hormones in four cell lines with excessive PTHrP production. Our study established that steroid hormones negatively regulate PTHrP expression. Vitamin D receptor, estrogen receptor α, glucocorticoid receptor, and progesterone receptor, were required for repression of PTHrP expression by the cognate ligands. A notable exception was the androgen receptor, which was dispensable for suppression of PTHrP expression in androgen-treated cells. We propose a pathway(s) involving nuclear receptors to suppress PTHrP expression.
Subject(s)
Hormones/physiology , Parathyroid Hormone-Related Protein/antagonists & inhibitors , Parathyroid Hormone-Related Protein/biosynthesis , Steroids/physiology , Cell Line , Cell Line, Tumor , Down-Regulation , Hormones/pharmacology , Humans , Parathyroid Hormone-Related Protein/genetics , Protein Biosynthesis/drug effects , Protein Biosynthesis/genetics , Protein Biosynthesis/physiology , Steroids/pharmacologyABSTRACT
Molecular mechanisms of intracellular response after DNA-damage by exposure to ionizing radiation have been studied. In the case of cells isolated from living body of human and experimental animals, alteration of the responsiveness by physiological oscillation such as circadian rhythm must be considered. To examine the circadian variation in the response of p53-responsible genes p21, mdm2, bax, and puma, we established a method to quantitate their mRNA levels with high reproducibility and accuracy based on real-time RT-PCR and compared the levels of responsiveness in mouse hemocytes after diurnal irradiation to that after nocturnal irradiation. Augmentations of p21 and mdm2 mRNA levels with growth-arrest and of puma mRNA before apoptosis were confirmed by time-course experiment in RAW264.7, and dose-dependent increases in the peak levels of all the RNA were shown. Similarly, the relative RNA levels of p21, mdm2, bax, and puma per GAPDH also increased dose-dependently in peripheral blood and bone marrow cells isolated from whole-body-irradiated mice. Induction levels of all messages reduced by half after nighttime irradiation as compared with daytime irradiation in blood cells. In marrow cells, nighttime irradiation enhanced the p21 and mdm2 mRNA levels than daytime irradiation. No significant difference in bax or puma mRNA levels was observed between nighttime and daytime irradiation in marrow cells. This suggests that early-stage cellular responsiveness in DNA damage-induced genes is modulated between diurnal and nocturnal irradiation.
Subject(s)
Circadian Rhythm , Animals , Cyclin-Dependent Kinase Inhibitor p21/metabolism , DNA Damage , Dose-Response Relationship, Radiation , Male , Mice , Mice, Inbred C3H , Proto-Oncogene Proteins c-mdm2/metabolism , RNA/metabolism , RNA, Messenger/metabolism , Reproducibility of Results , Reverse Transcriptase Polymerase Chain Reaction , Time Factors , Whole-Body IrradiationABSTRACT
We carried out a screen for Cryptococcus neoformans genes involved in resistance to copper ion toxicity and identified a new hexose transporter (Hxt) gene, HXT1. Hxt1 consists of 520 amino acids and functions to transport hexoses such as glucose. Although Hxt1 conferred copper resistance to Saccharomyces cerevisiae, disruption of the HXT1 gene showed that Hxt1 is not necessary for copper resistance. In virulence tests, an hxt1 mutant strain showed 12% less phenoloxidase activity than the wild-type strain, and no difference in the ability to form melanin was identified. In addition, the hxt1 mutant strain showed virulence similar to that of the wild-type strain in experiments with Caenorhabditis elegans. However, the hxt1 mutant strain generated larger capsules than were generated by the wild-type strain. Thus, Hxt1 appears to be involved in capsule formation.
Subject(s)
Cloning, Molecular , Copper/pharmacology , Cryptococcus neoformans/drug effects , Drug Resistance, Fungal/genetics , Monosaccharide Transport Proteins/genetics , Monosaccharide Transport Proteins/metabolism , Animals , Caenorhabditis elegans/drug effects , Caenorhabditis elegans/growth & development , Copper/toxicity , Cryptococcus neoformans/genetics , Cryptococcus neoformans/pathogenicity , DNA, Complementary , Drug Resistance, Fungal/drug effects , Fungal Proteins/genetics , Fungal Proteins/metabolism , Gene Expression Regulation, Fungal , Mutation , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae/metabolism , VirulenceABSTRACT
Two new decalin derivatives, eujavanoic acids A (1) and B (2), were isolated from Eupenicillium javanicum, along with several compactin derivatives. The structures of 1 and 2 were determined by spectroscopic methods and modified Mosher's method. The side chain (2-methylbutanoyloxy) and acid functionalities of compactin derivatives were necessary to show the antifungal activity.
