Abstract:
:Naturally occurring amino acid substitutions conferring resistance to methotrexate (MTX) have been reported previously at codon positions 22 (leu-->arg, phe) and 31 (phe-->ser, trp) of mammalian dihydrofolate reductases (DHFR). To explore the character of other substitutions, a polymerase chain reaction (PCR)-assisted saturation mutagenesis protocol was devised to introduce all possible codon sequences at positions 22 and 31 of the murine DHFR coding sequence in an expressible simian virus 40 (SV40)-regulated transcription unit. Nucleotide sequencing confirmed the presence of all four nucleotides at each of the three codon positions in the mutagenized material. Transfection of these "codon libraries" into DHFR-deficient Chinese hamster ovary cells resulted in an increased frequency of MTX-resistant colony formation in comparison with wild-type DHFR transfected cells. DHFR variants contained in different clones were characterized by PCR amplification and DNA sequencing, identifying six different amino acid substitutions at position 22 and seven substitutions at position 31. DHFR variants were extracted for determination of MTX inhibition character and catalytic activity, normalizing for the amount of DHFR protein by western blot analysis. A wide range of MTX sensitivities and catalytic activities were observed which is consistent with the role of these side chains in DHFR catalytic function. We observed that codon 22 variants were generally more resistant to MTX, but codon 31 variants retained substantially more catalytic activity (about 2.5-fold) at a given level of MTX resistance. This heterogeneity in catalytic and inhibition character has important implications for the function of different DHFR variants as mediators of drug resistance.
journal_name
Biochem Pharmacoljournal_title
Biochemical pharmacologyauthors
Morris JA,McIvor RSdoi
10.1016/0006-2952(94)90393-xsubject
Has Abstractpub_date
1994-03-29 00:00:00pages
1207-20issue
7eissn
0006-2952issn
1873-2968pii
0006-2952(94)90393-Xjournal_volume
47pub_type
杂志文章abstract::Piperine and two of its derivatives, antiepilepsirine (AE or 3,4-methylendioxycynnamoylpiperine) and compound 7448 (N-isopropyl 3 (4 chloro-phenyl) propenoylamide) are very effective in stimulating serotonin (5HT) synthesis. AE raises the ratio of free-to-bound tryptophan (TP) in plasma and induces a long-lasting incr...
journal_title:Biochemical pharmacology
pub_type: 杂志文章
doi:10.1016/0006-2952(84)90055-8
更新日期:1984-12-01 00:00:00
abstract::Multidrug resistance in tumor cells is often associated with the presence of an approximately 170 kDa plasma membrane glycoprotein (Pgp) that acts as a drug-efflux pump and decreases intracellular antitumor drug concentration. We measured the uptake of seven anthracyclines (daunorubicin, doxorubicin, 4'-epi-doxorubici...
journal_title:Biochemical pharmacology
pub_type: 杂志文章
doi:10.1016/0006-2952(96)00042-1
更新日期:1996-05-17 00:00:00
abstract::The mechanism of activation of microsomal glutathione transferase in isolated liver cells by diisapropylidene acetone (phorone) was investigated. Phorone (1 mM) causes a time-dependent increase (up to 2.6-fold) in the glutathione transferase activity of microsomes isolated from treated hepatocytes. Since phorone react...
journal_title:Biochemical pharmacology
pub_type: 杂志文章
doi:10.1016/0006-2952(92)90269-o
更新日期:1992-01-22 00:00:00
abstract::Only very low levels of peroxidase activity were detected in castrated male hamster kidneys [1.0 +/- 0.8(S.E.) units/g protein], and chronic estrogen administration, either diethylstilbestrol (DES) or 17 beta-estradiol, for 1-5 months did not result in any appreciable increase in this activity. In contrast, hamster li...
journal_title:Biochemical pharmacology
pub_type: 杂志文章
doi:10.1016/0006-2952(83)90529-4
更新日期:1983-02-01 00:00:00
abstract::Folate-binding protein (FBP), a high-affinity folate receptor, is responsible for cellular accumulation of folate and folate analogs such as methotrexate in human KB (nasopharyngeal carcinoma) cells. Both FBP and FBP mRNA increase 3- to 5-fold when KB cells are grown in folate-deficient (less than 10 nM folate) medium...
journal_title:Biochemical pharmacology
pub_type: 杂志文章
doi:10.1016/0006-2952(93)90235-o
更新日期:1993-06-22 00:00:00
abstract::beta-Antiadrenergic properties are part of the pharmacological characteristics of amiodarone. In the present study, the action of amiodarone on rat-heart beta-adrenoceptors was investigated. [125I]Cyanopindolol (CYP) was used to label beta-adrenoceptors in crude rat-heart microsomes. In competition binding experiments...
journal_title:Biochemical pharmacology
pub_type: 杂志文章
doi:10.1016/0006-2952(83)90004-7
更新日期:1983-09-01 00:00:00
abstract::MRP1 overexpression in multidrug-resistant cancer cells has been shown to be responsible for collateral sensitivity to some flavonoids that stimulate a huge MRP1-mediated GSH efflux. This massive GSH depletion triggers the death of these cancer cells. We describe here that bivalent flavonoid dimers strikingly stimulat...
journal_title:Biochemical pharmacology
pub_type: 杂志文章
doi:10.1016/j.bcp.2016.10.013
更新日期:2017-01-15 00:00:00
abstract::Deoxycytidine kinase (dCK) (EC 2.7.1.74) is a key enzyme in the activation of several therapeutic nucleoside analogs (NA). Its activity can be increased in vivo by Ser-74 phosphorylation, a property that could be used for enhancing NA activation and clinical efficacy. In line with this, studies with recombinant dCK sh...
journal_title:Biochemical pharmacology
pub_type: 杂志文章
doi:10.1016/j.bcp.2012.03.022
更新日期:2012-07-01 00:00:00
abstract::Cisplatin is a potent chemotherapeutic drug widely used for the treatment of human cancer. However, its efficacy against hepatocellular carcinoma (HCC) is poor for reasons that remain unclear. We show here that prothymosin-alpha (PTMA) is overexpressed in HCC cell lines. Silencing PTMA using short-hairpin RNA sensitiz...
journal_title:Biochemical pharmacology
pub_type: 杂志文章
doi:10.1016/j.bcp.2016.10.003
更新日期:2016-12-15 00:00:00
abstract::The effects of two recently developed alpha 2-adrenergic antagonists, RX 781094 and WY 26703, on the synthesis of norepinephrine (NE), dopamine (DA) and serotonin (5-HT) in rat brain were compared to those of yohimbine, its diastereoisomer rauwolscine, and mianserin. Intraperitoneal administration of these compounds i...
journal_title:Biochemical pharmacology
pub_type: 杂志文章
doi:10.1016/0006-2952(85)90614-8
更新日期:1985-04-01 00:00:00
abstract::Catalase, superoxide dismutase, and dimethylsulfoxide were tested for their ability to prevent the cytotoxic effect of 6-hydroxydopamine (6-OHDA) on the human neuroblastoma line SY5Y. Viability was measured at two time points after 6-OHDA treatment: at 3 hr by means of amino acid incorporation and at 24 hr by trypan b...
journal_title:Biochemical pharmacology
pub_type: 杂志文章
doi:10.1016/0006-2952(82)90208-8
更新日期:1982-01-15 00:00:00
abstract::Chlorpromazine, imipramine and amitriptyline, drugs structurally related to riboflavin, each inhibited the formation in vivo of flavin adenine dinucleotide (FAD) from riboflavin in rat heart at 2-5 mg/kg body weight, doses comparable on a weight basis to those used clinically. All three drugs inhibited FAD formation i...
journal_title:Biochemical pharmacology
pub_type: 杂志文章
doi:10.1016/0006-2952(82)90632-3
更新日期:1982-11-01 00:00:00
abstract::Indole alkaloids possess a large spectrum of biological activities including anti-protozoal action. Here we report for the first time that voacamine, isolated from the plant Tabernaemontana coronaria, is an antiprotozoal agent effective against a large array of trypanosomatid parasites including Indian strain of Leish...
journal_title:Biochemical pharmacology
pub_type: 杂志文章
doi:10.1016/j.bcp.2017.05.002
更新日期:2017-08-15 00:00:00
abstract::Oxidant damage from reactive oxygen species (ROS) and reactive nitrogen species (RNS) is a major contributor to the cellular damage seen in numerous types of renal injury. Resveratrol (trans-3,4',5-trihydroxystilbene) is a phytoalexin found naturally in many common food sources. The anti-oxidant properties of resverat...
journal_title:Biochemical pharmacology
pub_type: 杂志文章
doi:10.1016/j.bcp.2010.06.027
更新日期:2010-10-15 00:00:00
abstract::Anticoagulants and anti-platelet agents are simultaneously administrated in clinical practice (i.e. percutaneous coronary intervention), which cause significant risk of systemic bleeding. Targeted delivery of anticoagulants to the activated platelets at sites of vascular injuries may condense the site-specific anticoa...
journal_title:Biochemical pharmacology
pub_type: 杂志文章
doi:10.1016/j.bcp.2015.04.004
更新日期:2015-06-15 00:00:00
abstract::It has been reported that endothelins (ETs) stimulate catecholamine release from chromaffin cells. However, it is not known whether ETs also affect catecholamine biosynthesis. Thus, using a rat pheochromocytoma cell line, PC12, we examined the effects of ETs on catecholamine biosynthesis. The mRNA level and activity o...
journal_title:Biochemical pharmacology
pub_type: 杂志文章
doi:10.1016/s0006-2952(01)00862-0
更新日期:2002-03-01 00:00:00
abstract::Rational approaches to targeted cancer therapy have begun to predominate the pipelines of oncology drug development. Our rapidly increasing understanding of the "wiring" of tumor cells and the vulnerabilities of such cells that can potentially be exploited through targeted treatments has opened up enormous opportuniti...
journal_title:Biochemical pharmacology
pub_type: 杂志文章,评审
doi:10.1016/j.bcp.2010.03.001
更新日期:2010-09-01 00:00:00
abstract::Cobalt protoporphyrin generated from 5-amino[4-14C]laevulinate by homogenates or primary cultures of chick embryo liver exposed to CoCl2 was found to be radioactivity unextractable by acid/acetone, when extra protein was added. The activity of ferrochelatase was required for formation of cobalt protoporphyrin since in...
journal_title:Biochemical pharmacology
pub_type: 杂志文章
doi:10.1016/0006-2952(82)90333-1
更新日期:1982-03-15 00:00:00
abstract::The tetracyclines inhibit specifically mitochondrial (mt) and bacterial protein synthesis when they are present in low concentrations (2-10 micrograms/ml). There is no difference between the various members of this group of antibiotics in this respect. In the present study, however, it is shown that the inhibitory eff...
journal_title:Biochemical pharmacology
pub_type: 杂志文章
doi:10.1016/0006-2952(87)90126-2
更新日期:1987-05-01 00:00:00
abstract::Glutathione (GSH) is important in protection of cells against electrophilic drug injury and against reactive oxygen species. Both steady-state concentrations and turnover of GSH are important determinants of susceptibility of the hepatocyte to injury. Chronic ethanol administration is known to enhance susceptibility t...
journal_title:Biochemical pharmacology
pub_type: 杂志文章
doi:10.1016/0006-2952(85)90699-9
更新日期:1985-05-01 00:00:00
abstract::Adenine nucleotides play an important role in the control of membrane potential by acting on ATP-sensitive K+ (K(ATP)) channels and, in turn, modulating the open probability of voltage-gated Ca2+ channels in pancreatic islet beta-cells. Here, we provide evidence that guanine nucleotides (GNs) also may be involved in t...
journal_title:Biochemical pharmacology
pub_type: 杂志文章
doi:10.1016/s0006-2952(99)00356-1
更新日期:2000-03-01 00:00:00
abstract::Glucuronidation, catalyzed by UDP-glucuronosyltransferases (UGTs), is a crucial substance metabolism and elimination process that mostly occurs in the liver to protect the body from toxic substances and maintain homeostasis. The reaction functions well in a uridine diphosphate glucuronic acid (UDPGA) -dependent manner...
journal_title:Biochemical pharmacology
pub_type: 杂志文章
doi:10.1016/j.bcp.2019.113753
更新日期:2020-02-01 00:00:00
abstract::ATP-dependent coenzyme A (CoA) ligases catalyse the formation of the acyl-CoA thioesters of xenobiotic carboxylic acids and the formation of xenobiotic-CoAs has been implicated as being a causative factor in peroxisomal proliferation. In this study we have demonstrated using rat liver peroxisomes that the formation of...
journal_title:Biochemical pharmacology
pub_type: 杂志文章
doi:10.1016/0006-2952(92)90008-7
更新日期:1992-07-22 00:00:00
abstract::MCF-7 human breast cancer cell homogenates and subcellular organelles were submitted to isopycnic centrifugation on Percoll gradients to investigate the subcellular localization of triphenylethylene antiestrogen specific binding sites (AEBS). Electron microscopy revealed that gradient fractions coincident with the mig...
journal_title:Biochemical pharmacology
pub_type: 杂志文章
doi:10.1016/0006-2952(86)90677-5
更新日期:1986-11-01 00:00:00
abstract::Phospholipase A2 (PLA2) cleave phospholipids preferentially at the sn-2 position, liberating free fatty acids and lysophospholipids. They are classified into six main groups based on size, location, function, substrate specificity and calcium requirement. These classes include secretory PLA2 (sPLA2), cytosolic (cPLA2)...
journal_title:Biochemical pharmacology
pub_type: 杂志文章,评审
doi:10.1016/j.bcp.2014.05.022
更新日期:2014-08-15 00:00:00
abstract::Rats were made vitamin K-deficient by feeding them a diet devoid of vitamin K and by rigorously preventing coprophagy. After one week, circulating prothrombin concentrations were between 5 and 10% of initial values, and various amounts of phylloquinone, menaquinone-4, and menaquinone-9 were given in a single dose eith...
journal_title:Biochemical pharmacology
pub_type: 杂志文章
doi:10.1016/0006-2952(95)00202-b
更新日期:1995-09-07 00:00:00
abstract::The existence of a distinct pool of glutathione in the nucleus of cultured human melanoma cells was demonstrated. Melanoma cell nuclei contained 13-35 pmol of glutathione/10(6) nuclei, or approximately 0.4-1.3% of the total cellular glutathione. This nuclear glutathione pool resisted depletion by buthionine sulfoximin...
journal_title:Biochemical pharmacology
pub_type: 杂志文章
doi:10.1016/0006-2952(92)90540-y
更新日期:1992-10-06 00:00:00
abstract::Incubation of human carcinoma cells with mitoxantrone resulted in an intracellular distribution of the drug into cytoplasmic, nuclear and cytoskeletal compartments occurring within 1 min of drug treatment. Incubation of the cells in drug-free medium resulted in an efflux of the drug such that 80% of the intracellular ...
journal_title:Biochemical pharmacology
pub_type: 杂志文章
doi:10.1016/0006-2952(89)90527-3
更新日期:1989-12-01 00:00:00
abstract::The participation of mitochondria in the mechanism of tumor cell death induced by non-steroid anti-inflammatory drugs is uncertain. Here we show that ibuprofen induces death of Walker 256 tumor cells independently on mitochondrial depolarization as estimated by flow cytometry using DioC(6)(3). Oligomycin increased mit...
journal_title:Biochemical pharmacology
pub_type: 杂志文章
doi:10.1016/j.bcp.2004.08.006
更新日期:2004-12-01 00:00:00
abstract::LLC-PK(1) is a proximal tubular cell line derived from normal pig kidney which has a structure and function similar to those of renal proximal tubular cells and which expresses baseline levels of P-glycoprotein. We isolated by drug selection a doxorubicin-resistant cell line (LLC-PK(1)/ADR) that exhibited a multidrug-...
journal_title:Biochemical pharmacology
pub_type: 杂志文章
doi:10.1016/s0006-2952(00)00535-9
更新日期:2001-01-01 00:00:00