Hydroxy[14C]urea uptake by normal and transformed human cells: evidence for a mechanism of passive diffusion

1987 ◽  
Vol 65 (11) ◽  
pp. 925-929 ◽  
Author(s):  
Aaron Y. Tagger ◽  
Joan Boux ◽  
Jim A. Wright
Keyword(s):  
Drug Transport ◽  
Human Cancer ◽  
Antitumor Agent ◽  
Human Cells ◽  
Drug Uptake ◽  
Metabolic Inhibitors ◽  
Proliferating Cells ◽  
Sv40 Virus ◽  
Human Diploid Fibroblasts ◽  
Urea Uptake

The antitumor agent hydroxyurea is a potent inhibitor of cell division and selectivity toxic for rapidly proliferating cells. This drug has been used in the treatment of human cancer and, since drug transport is an important aspect of drug action, we investigated the mechanism of hydroxy[14C]urea uptake by human diploid fibroblasts and their SV40-virus-transformed counterparts. Kinetic analysis of drug uptake, studies with metabolic inhibitors, and estimates of cell/medium distribution ratios and temperature coefficient (Q10) values indicated that hydroxyurea enters normal and SV40-virus-transformed human cells by a mechanism of diffusion.

scholarly journals Inverse mechanistic modeling of transdermal drug delivery for fast identification of optimal model parameters

2020 ◽  
Author(s):  
Thijs Defraeye ◽  
Flora Bahrami ◽  
Rene M Rossi
Keyword(s):  
Drug Delivery ◽  
Inverse Modeling ◽  
Transdermal Drug Delivery ◽  
Drug Transport ◽  
Mechanistic Model ◽  
Mechanistic Modeling ◽  
Drug Uptake ◽  
Added Value ◽  
Model Parameters ◽  
Transdermal Drug Delivery Systems

Transdermal drug delivery systems are a key technology to administer drugs with a high first-pass effect in a non-invasive and controlled way. Physics-based modeling and simulation are on their way to become a cornerstone in the engineering of these healthcare devices since it provides a unique complementarity to experimental data and insights. Simulations enable to virtually probe the drug transport inside the skin at each point in time and space. However, the tedious experimental or numerical determination of material properties currently forms a bottleneck in the modeling workflow. We show that multiparameter inverse modeling to determine the drug diffusion and partition coefficients is a fast and reliable alternative. We demonstrate this strategy for transdermal delivery of fentanyl. We found that inverse modeling reduced the normalized root mean square deviation of the measured drug uptake flux from 26 to 9%, when compared to the experimental measurement of all skin properties. We found that this improved agreement with experiments was only possible if the diffusion in the reservoir holding the drug was smaller than the experimentally-measured diffusion coefficients suggested. For indirect inverse modeling, which systematically explores the entire parametric space, 30 000 simulations were required. By relying on direct inverse modeling, we reduced the number of simulations to be performed to only 300, so a factor 100 difference. The modeling approach's added value is that it can be calibrated once in-silico for all model parameters simultaneously by solely relying on a single measurement of the drug uptake flux evolution over time. We showed that this calibrated model could accurately be used to simulate transdermal patches with other drug doses. We showed that inverse modeling is a fast way to build up an accurate mechanistic model for drug delivery. This strategy opens the door to clinically-ready therapy that is tailored to patients.

scholarly journals MODELLING THE RESPONSE OF VASCULAR TUMOURS TO CHEMOTHERAPY: A MULTISCALE APPROACH

2006 ◽  
Vol 16 (supp01) ◽  
pp. 1219-1241 ◽  
Author(s):  
HELEN M. BYRNE ◽  
MARKUS R. OWEN ◽  
TOMAS ALARCON ◽  
JAMES MURPHY ◽  
PHILIP K. MAINI
Keyword(s):  
Cell Density ◽  
Tumour Cell ◽  
Drug Transport ◽  
Angiogenic Factors ◽  
Future Research ◽  
Model Parameters ◽  
Multiscale Approach ◽  
Proliferating Cells ◽  
Vascular Adaptation ◽  
Spatio Temporal

An existing multiscale model is extended to study the response of a vascularised tumour to treatment with chemotherapeutic drugs which target proliferating cells. The underlying hybrid cellular automaton model couples tissue-level processes (e.g. blood flow, vascular adaptation, oxygen and drug transport) with cellular and subcellular phenomena (e.g. competition for space, progress through the cell cycle, natural cell death and drug-induced cell kill and the expression of angiogenic factors). New simulations suggest that, in the absence of therapy, vascular adaptation induced by angiogenic factors can stimulate spatio-temporal oscillations in the tumour's composition. Numerical simulations are presented and show that, depending on the choice of model parameters, when a drug which kills proliferating cells is continuously infused through the vasculature, three cases may arise: the tumour is eliminated by the drug; the tumour continues to expand into the normal tissue; or, the tumour undergoes spatio-temporal oscillations, with regions of high vascular and tumour cell density alternating with regions of low vascular and tumour cell density. The implications of these results and possible directions for future research are also discussed.

scholarly journals Wnt Effector TCF4 Is Dispensable for Wnt Signaling in Human Cancer Cells

Genes ◽  
2018 ◽  
Vol 9 (9) ◽  
pp. 439 ◽  
Author(s):  
Dusan Hrckulak ◽  
Lucie Janeckova ◽  
Lucie Lanikova ◽  
Vitezslav Kriz ◽  
Monika Horazna ◽  
...  
Keyword(s):  
T Cell ◽  
Wnt Signaling ◽  
Cancer Cells ◽  
Human Cancer ◽  
Wnt Signaling Pathway ◽  
Human Cells ◽  
Cellular Systems ◽  
Mouse Tissue ◽  
T Cell Factor ◽  
Human Cancer Cells

T-cell factor 4 (TCF4), together with β-catenin coactivator, functions as the major transcriptional mediator of the canonical wingless/integrated (Wnt) signaling pathway in the intestinal epithelium. The pathway activity is essential for both intestinal homeostasis and tumorigenesis. To date, several mouse models and cellular systems have been used to analyze TCF4 function. However, some findings were conflicting, especially those that were related to the defects observed in the mouse gastrointestinal tract after Tcf4 gene deletion, or to a potential tumor suppressive role of the gene in intestinal cancer cells or tumors. Here, we present the results obtained using a newly generated conditional Tcf4 allele that allows inactivation of all potential Tcf4 isoforms in the mouse tissue or small intestinal and colon organoids. We also employed the clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 system to disrupt the TCF4 gene in human cells. We showed that in adult mice, epithelial expression of Tcf4 is indispensable for cell proliferation and tumor initiation. However, in human cells, the TCF4 role is redundant with the related T-cell factor 1 (TCF1) and lymphoid enhancer-binding factor 1 (LEF1) transcription factors.

scholarly journals With Age Comes Maturity: Biochemical and Structural Transformation of a Human Centriole in the Making

Cells ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 1429 ◽  
Author(s):  
Catherine Sullenberger ◽  
Alejandra Vasquez-Limeta ◽  
Dong Kong ◽  
Jadranka Loncarek
Keyword(s):  
S Phase ◽  
Human Cells ◽  
Cellular Structures ◽  
Age Difference ◽  
Proliferating Cells ◽  
Cell Cycles ◽  
Controlled Processes ◽  
The Third ◽  
Centriole Assembly ◽  
Lengthy Process

Centrioles are microtubule-based cellular structures present in most human cells that build centrosomes and cilia. Proliferating cells have only two centrosomes and this number is stringently maintained through the temporally and spatially controlled processes of centriole assembly and segregation. The assembly of new centrioles begins in early S phase and ends in the third G1 phase from their initiation. This lengthy process of centriole assembly from their initiation to their maturation is characterized by numerous structural and still poorly understood biochemical changes, which occur in synchrony with the progression of cells through three consecutive cell cycles. As a result, proliferating cells contain three structurally, biochemically, and functionally distinct types of centrioles: procentrioles, daughter centrioles, and mother centrioles. This age difference is critical for proper centrosome and cilia function. Here we discuss the centriole assembly process as it occurs in somatic cycling human cells with a focus on the structural, biochemical, and functional characteristics of centrioles of different ages.

scholarly journals Reversing the direction of drug transport mediated by the human multidrug transporter P-glycoprotein

2020 ◽  
Vol 117 (47) ◽  
pp. 29609-29617
Author(s):  
Andaleeb Sajid ◽  
Sabrina Lusvarghi ◽  
Megumi Murakami ◽  
Eduardo E. Chufan ◽  
Biebele Abel ◽  
...  
Keyword(s):  
Drug Transport ◽  
Atp Hydrolysis ◽  
Binding Pocket ◽  
Drug Binding ◽  
Drug Uptake ◽  
Cancer Drug ◽  
Binding Domains ◽  
Cancer Drug Resistance ◽  
P Glycoprotein ◽  
Cell Transforming

P-glycoprotein (P-gp), also known as ABCB1, is a cell membrane transporter that mediates the efflux of chemically dissimilar amphipathic drugs and confers resistance to chemotherapy in most cancers. Homologous transmembrane helices (TMHs) 6 and 12 of human P-gp connect the transmembrane domains with its nucleotide-binding domains, and several residues in these TMHs contribute to the drug-binding pocket. To investigate the role of these helices in the transport function of P-gp, we substituted a group of 14 conserved residues (seven in both TMHs 6 and 12) with alanine and generated a mutant termed 14A. Although the 14A mutant lost the ability to pump most of the substrates tested out of cancer cells, surprisingly, it acquired a new function. It was able to import four substrates, including rhodamine 123 (Rh123) and the taxol derivative flutax-1. Similar to the efflux function of wild-type P-gp, we found that uptake by the 14A mutant is ATP hydrolysis-, substrate concentration-, and time-dependent. Consistent with the uptake function, the mutant P-gp also hypersensitizes HeLa cells to Rh123 by 2- to 2.5-fold. Further mutagenesis identified residues from both TMHs 6 and 12 that synergistically form a switch in the central region of the two helices that governs whether a given substrate is pumped out of or into the cell. Transforming P-gp or an ABC drug exporter from an efflux transporter into a drug uptake pump would constitute a paradigm shift in efforts to overcome cancer drug resistance.

scholarly journals Transfer of malignant trait to immortalized human cells following exposure to human cancer serum

2014 ◽  
Vol 33 (1) ◽  
Author(s):  
Mohamed Abdouh ◽  
Shufeng Zhou ◽  
Vincenzo Arena ◽  
Manuel Arena ◽  
Anthoula Lazaris ◽  
...  
Keyword(s):  
Human Cancer ◽  
Human Cells

scholarly journals Invasion of Normal Human Fibroblasts Induced by v-FosIs Independent of Proliferation, Immortalization, and theTumor Suppressors p16INK4a andp53

2004 ◽  
Vol 24 (4) ◽  
pp. 1540-1559 ◽  
Author(s):  
Linda A. Scott ◽  
J. Keith Vass ◽  
E. Kenneth Parkinson ◽  
David A. F. Gillespie ◽  
Joseph N. Winnie ◽  
...  
Keyword(s):  
Gene Expression ◽  
Growth Factor ◽  
Human Cancer ◽  
Human Fibroblasts ◽  
Growth Factor Receptor ◽  
Dysplastic Lesion ◽  
Human Diploid Fibroblasts ◽  
Affymetrix Genechips ◽  
Late Event ◽  
Normal Human

ABSTRACT Invasion is generally perceived to be a late event during the progression of human cancer, but to date there are no consistent reports of alterations specifically associated with malignant conversion. We provide evidence that the v-Fos oncogene induces changes in gene expression that render noninvasive normal human diploid fibroblasts highly invasive, without inducing changes in growth factor requirements or anchorage dependence for proliferation. Furthermore, v-Fos-stimulated invasion is independent of the pRb/p16INK4a and p53 tumor suppressor pathways and telomerase. We have performed microarray analysis using Affymetrix GeneChips, and the gene expression profile of v-Fos transformed cells supports its role in the regulation of invasion, independent from proliferation. We also demonstrate that invasion, but not proliferation, is dependent on the activity of the up-regulated epidermal growth factor receptor. Taken together, these results indicate that AP-1-directed invasion could precede deregulated proliferation during tumorigenesis and that sustained activation of AP-1 could be the epigenetic event required for conversion of a benign tumor into a malignant one, thereby explaining why many malignant human tumors present without an obvious premalignant hyperproliferative dysplastic lesion.

scholarly journals Linear and cyclic peptides as substrates and modulators of P-glycoprotein: peptide binding and effects on drug transport and accumulation

1998 ◽  
Vol 333 (3) ◽  
pp. 621-630 ◽  
Author(s):  
Frances J. SHAROM ◽  
Peihua LU ◽  
Ronghua LIU ◽  
Xiaohong YU
Keyword(s):  
Cyclic Peptides ◽  
Drug Transport ◽  
Membrane Vesicles ◽  
Drug Uptake ◽  
Multidrug Transporter ◽  
Chemotherapeutic Drugs ◽  
Plasma Membrane Vesicles ◽  
Hydrophobic Peptides ◽  
P Glycoprotein ◽  
Highly Correlated

One cause of multidrug resistance (MDR) in human cancers is the overexpression of the P-glycoprotein multidrug transporter, a member of the ABC superfamily of membrane proteins. Natural products and chemotherapeutic drugs are pumped out of the cell by P-glycoprotein in an ATP-dependent fashion. There is growing evidence that many hydrophobic peptides are also P-glycoprotein substrates. With the use of a fluorescence-quenching assay, we have shown that some linear and cyclic hydrophobic peptides interact with P-glycoprotein, whereas others do not. The measured values of the quenching constant, Kq, for interaction of peptides with P-glycoprotein ranged from 200 nM for cyclosporine A to 138 µM for the tripeptide N-acetyl-leucyl-leucyl-norleucinal. Peptides that interacted with P-glycoprotein in the fluorescence assay also blocked colchicine transport into plasma membrane vesicles from MDR cells. The values of Dm, the peptide concentration causing 50% inhibition of drug uptake, were highly correlated with the values of Kq, over three orders of magnitude. The P-glycoprotein ATPase stimulation/inhibition profile of the peptides was not helpful in making a quantitative assessment of the ability of a peptide to interact with P-glycoprotein or to block drug transport. Some hydrophobic peptides were able to restore accumulation in MDR cells of the chemotherapeutic drug daunorubicin and the fluorescent dye rhodamine 123 to the levels observed in the drug-sensitive parent. Peptides that interacted with P-glycoprotein also displayed a relatively low overall toxicity to intact MDR cells, and inhibited drug transport at concentrations below the toxic range. Hydrophobic peptides should be given serious consideration for development as clinical chemosensitizing agents.

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