Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.4.2.8 (hypoxanthine-guanine phosphoribosyltransferase)
 2,527 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A plasmid carrying antisense human MYC DNA and the gene encoding Escherichia coli xanthine/guanine phosphoribosyltransferase (Ecogpt) was introduced into human promyelocytic leukemia cell line HL-60 by protoplast fusion. High-level expression of antisense MYC RNA was obtained by selecting cells resistant to progressively higher levels of mycophenolic acid over a period of greater than 6 months. The constitutive production of MYC protein in clones producing high levels of antisense MYC RNA was reduced by 70% compared to parental HL-60 cells. Inhibition of MYC expression was observed not only at the translational but also at the transcriptional level, implying that antisense RNA can regulate transcription of the MYC gene. The Pst I-Pvu II fragment (920 base pairs) of the MYC leader sequence is the primary transcriptional target of the antisense RNA. The suppression of endogenous MYC gene expression by antisense RNA decreases cell proliferation and triggers monocytic differentiation.
 ...
PMID:Transcriptional control of the endogenous MYC protooncogene by antisense RNA. 244 81

Di-(2-ethylhexyl) phthalate (DEHP), the common plasticizer used in the production of polyvinyl chloride, can be converted to the more potent metabolite mono-ethylhexyl phthalate (MEHP). Epidemiological studies have shown an association with elevated induction of rat hepatic cancer and reproductive toxicity in response to MEHP exposure. However, the mechanism of genotoxicity and carcinogenicity induced by MEHP treatment remains unclear. As a means to elucidate the mechanisms of action, lethality and mutagenicity in the adenine phosphoribosyltransferase (aprt+/-) gene induced in several CHO cell types by MEHP were assessed. Dose-response relationships were determined in the parental AA8 cell line, its nucleotide repair-deficient UV5 and base repair-deficient EM9 subclones, and also in AS52 cells harboring the bacterial guanine-hypoxanthine phosphoribosyltransferase (gpt) gene and its derived AS52-XPD-knockdown and AS52-PARP-1-knockdown cells. Treatment of AS52 with MEHP led to intracellular production of reactive oxygen species (ROS) and DNA strand breaks in a dose-dependent manner. Separately, mutations in the gpt gene of AS52 cells were characterized and found to be dominated by G:C to A:T and A:T to G:C transitions. Independent AS52-mutant cell (ASMC) clones were collected for the sequential in vivo xenograft tumorigenic studies, 4 of total 20 clones had aggressive tumor growth. Moreover, microarray analysis indicated miR-let-7a and miR-125b downregulated in ASMC, which might raise oncogenic MYC and RAS level and activate ErbB pathway. Comparative evaluation of the results indicates that the principal mechanism of this mutagenic action is probably to be through generation of ROS, causing base excision damage resulting in carcinogenicity.
 ...
PMID:Acute exposure to DEHP metabolite, MEHP cause genotoxicity, mutagenesis and carcinogenicity in mammalian Chinese hamster ovary cells. 2842 79