Katalin Goda | University of Debrecen (original) (raw)
Papers by Katalin Goda
International Journal of Molecular Sciences
The human P-glycoprotein (P-gp), a transporter responsible for multidrug resistance, is present i... more The human P-glycoprotein (P-gp), a transporter responsible for multidrug resistance, is present in the plasma membrane’s raft and non-raft domains. One specific conformation of P-gp that binds to the monoclonal antibody UIC2 is primarily associated with raft domains and displays heightened internalization in cells overexpressing P-gp, such as in NIH-3T3 MDR1 cells. Our primary objective was to investigate whether the trafficking of this particular P-gp conformer is dependent on cholesterol levels. Surprisingly, depleting cholesterol using cyclodextrin resulted in an unexpected increase in the proportion of raft-associated P-gp within the cell membrane, as determined by UIC2-reactive P-gp. This increase appears to be a compensatory response to cholesterol loss from the plasma membrane, whereby cholesterol-rich raft micro-domains are delivered to the cell surface through an augmented exocytosis process. Furthermore, this exocytotic event is found to be part of a complex trafficking me...
International Journal of Molecular Sciences
The human ABCB1 (P-glycoprotein, Pgp) protein is an active exporter expressed in the plasma membr... more The human ABCB1 (P-glycoprotein, Pgp) protein is an active exporter expressed in the plasma membrane of cells forming biological barriers. In accordance with its broad substrate spectrum and tissue expression pattern, it affects the pharmacokinetics of numerous chemotherapeutic drugs and it is involved in unwanted drug–drug interactions leading to side effects or toxicities. When expressed in tumor tissues, it contributes to the development of chemotherapy resistance in malignancies. Therefore, the understanding of the molecular details of the ligand–ABCB1 interactions is of crucial importance. In a previous study, we found that quercetin (QUR) hampers both the transport and ATPase activity of ABCB1, while cyandin-3O-sophroside (C3S) stimulates the ATPase activity and causes only a weak inhibition of substrate transport. In the current study, when QUR and C3S were applied together, both a stronger ATPase inhibition and a robust decrease in substrate transport were observed, supporti...
Life, 2021
We studied the effect of different magnitudes (7000 PSI (48.26 MPa), 8000 PSI (55.16 MPa), and 90... more We studied the effect of different magnitudes (7000 PSI (48.26 MPa), 8000 PSI (55.16 MPa), and 9000 PSI (62.05 MPa)) of hydrostatic pressure on the ploidy of pikeperch larvae. Pressure shock was applied 5 min after the fertilization of eggs at a water temperature of 14.8 ± 1 °C. A 7000 PSI pressure shock was applied for 10 or 20 min, while 8000 and 9000 PSI treatments lasted for 10 min. Each treatment with its respective control was completed in triplicate, where different females’ eggs served as a replicate. In the treatment groups exposed to 7000 PSI for 10 min, only diploid and triploid larvae were identified, while 2n/3n mosaic individuals were found after a 20-min exposure to a 7000 PSI pressure shock. The application of 8000 or 9000 PSI pressure shocks resulted in only triploid and mosaic individuals. Among larvae from eggs treated with 8000 PSI, three mosaic individuals with 2n/3n karyotype were identified (4.0 ± 6.9%), while a single (2.0 ± 3.5%) 1n/3n mosaic individual was ...
Biophysical Journal, 2017
Cancer detection and prevention, 2000
P-glycoprotein (P-gp) acts as an active efflux mechanism for a large number of cytostatics and se... more P-glycoprotein (P-gp) acts as an active efflux mechanism for a large number of cytostatics and seems to be involved in the frequent failure of cancer chemotherapy. The molecular events of substrate recognition and transport still are not understood completely. We show here that the percentage of P-gp epitopes available for labeling with UIC2 monoclonal antibody is increased significantly after methanol permeabilization/fixation of cells. At the same time, binding of the MRK16 and 4E3 anti-P-gp antibodies is changed only moderately. Confocal microscopical images of UIC2-PE-labeled cells show that the epitopes becoming available after fixation are situated mainly in the plasma membrane. Thus, only a minority of P-gp molecules are accessible for UIC2 in the cell membrane of live cells, and methanol treatment can expose a large pool of previously plasma membrane-embedded, cryptic UIC2 epitopes. The UIC2-reactive P-gp molecules do not appear to be sequestered spatially, as suggested by t...
ABCG2 is an exporter type ABC protein that can expel numerous chemically unrelated xeno- and endo... more ABCG2 is an exporter type ABC protein that can expel numerous chemically unrelated xeno- and endobiotics from cells. When expressed in tumor cells or tumor stem cells, ABCG2 confers multidrug resistance, contributing to the failure of chemotherapy.Molecular details orchestrating substrate translocation and ATP hydrolysis remain elusive. Here we present methods to concomitantly investigate substrate and nucleotide binding by ABCG2 in cells. Using the conformation-sensitive antibody 5D3, we show that the switch from the inward-facing (IF) to the outward-facing (OF) conformation of ABCG2 is induced by nucleotide binding. IF-OF transition is facilitated by substrates, and hindered by the inhibitor Ko143. Direct measurements of 5D3 and substrate binding to ABCG2 indicate that the high-to-low affinity switch of the drug binding site coincides with the transition from the IF to the OF conformation. Low substrate binding persists in the post-hydrolysis state, supporting that dissociation of...
PLOS Genetics, 2020
Several ABC exporters carry a degenerate nucleotide binding site (NBS) that is unable to hydrolyz... more Several ABC exporters carry a degenerate nucleotide binding site (NBS) that is unable to hydrolyze ATP at a rate sufficient for sustaining transport activity. A hallmark of a degenerate NBS is the lack of the catalytic glutamate in the Walker B motif in the nucleotide binding domain (NBD). The multidrug resistance transporter ABCB1 (P-glycoprotein) has two canonical NBSs, and mutation of the catalytic glutamate E556 in NBS1 renders ABCB1 transport-incompetent. In contrast, the closely related bile salt export pump ABCB11 (BSEP), which shares 49% sequence identity with ABCB1, naturally contains a methionine in place of the catalytic glutamate. The NBD-NBD interfaces of ABCB1 and ABCB11 differ only in four residues, all within NBS1. Mutation of the catalytic glutamate in ABCB1 results in the occlusion of ATP in NBS1, leading to the arrest of the transport cycle. Here we show that despite the catalytic glutamate mutation (E556M), ABCB1 regains its ATP-dependent transport activity, when three additional diverging residues are also replaced. Molecular dynamics simulations revealed that the rescue of ATPase activity is due to the modified geometry of NBS1, resulting in a weaker interaction with ATP, which allows the quadruple mutant to evade the conformationally locked pre-hydrolytic state to proceed to ATP-driven transport. In summary, we show that ABCB1 can be transformed into an active transporter with only one functional catalytic site by preventing the formation of the ATP-locked pre-hydrolytic state in the non-canonical site.
![Research paper thumbnail of 2'[(18)F]-fluoroethylrhodamine B is a promising radiotracer to measure P-glycoprotein function](https://attachments.academia-assets.com/99718815/thumbnails/1.jpg)
](European journal of pharmaceutical sciences : official journal of the European Federation for Pharmaceutical Sciences, Jan 6, 2015
In vivo detection of the emergence of P-glycoprotein (Pgp) mediated multidrug resistance in tumor... more In vivo detection of the emergence of P-glycoprotein (Pgp) mediated multidrug resistance in tumors could be beneficial for patients treated with anticancer drugs. PET technique in combination with appropriate radiotracers could be the most convenient method for detection of Pgp function. Rhodamine derivatives are validated fluorescent probes for measurement of mitochondrial membrane potential and also Pgp function. The aim of this study was to investigate whether 2'[(18)F]-fluoroethylrhodamine B ((18)FRB) a halogenated rhodamine derivative previously synthesized for PET assessment of myocardial perfusion preserved its Pgp substrate character. ATPase assay as well as accumulation experiments carried out using Pgp(+) and Pgp(-) human gynecologic (A2780/A2780(AD) and KB-3-1/KB-V1) and a mouse fibroblast cell pairs (NIH 3T3 and NIH 3T3 MDR1) were applied to study the interaction of (18)FRB with Pgp. ATPase assay proved that (18)FRB is a high affinity substrate of Pgp. Pgp(-) cells a...
European journal of pharmaceutical sciences : official journal of the European Federation for Pharmaceutical Sciences, Jan 20, 2014
2-[(18)F]fluoro-2-deoxy-d-glucose ((18)FDG) is a tumor diagnostic radiotracer of great importance... more 2-[(18)F]fluoro-2-deoxy-d-glucose ((18)FDG) is a tumor diagnostic radiotracer of great importance in both diagnosing primary and metastatic tumors and in monitoring the efficacy of the treatment. P-glycoprotein (Pgp) is an active transporter that is often expressed in various malignancies either intrinsically or appears later upon disease progression or in response to chemotherapy. Several authors reported that the accumulation of (18)FDG in P-glycoprotein (Pgp) expressing cancer cells (Pgp(+)) and tumors is different from the accumulation of the tracer in Pgp nonexpressing (Pgp(-)) ones, therefore we investigated whether (18)FDG is a substrate or modulator of Pgp pump. Rhodamine 123 (R123) accumulation experiments and ATPase assay were used to detect whether (18)FDG is substrate for Pgp. The accumulation and efflux kinetics of (18)FDG were examined in two different human gynecologic (A2780/A2780AD and KB-3-1/KB-V1) and a mouse fibroblast (3T3 and 3T3MDR1) Pgp(+) and Pgp(-) cancer c...
PloS one, 2014
P-glycoprotein (Pgp) extrudes a large variety of chemotherapeutic drugs from the cells, causing m... more P-glycoprotein (Pgp) extrudes a large variety of chemotherapeutic drugs from the cells, causing multidrug resistance (MDR). The UIC2 monoclonal antibody recognizes human Pgp and inhibits its drug transport activity. However, this inhibition is partial, since UIC2 binds only to 10-40% of cell surface Pgps, while the rest becomes accessible to this antibody only in the presence of certain substrates or modulators (e.g. cyclosporine A (CsA)). The combined addition of UIC2 and 10 times lower concentrations of CsA than what is necessary for Pgp inhibition when the modulator is applied alone, decreased the EC50 of doxorubicin (DOX) in KB-V1 (Pgp+) cells in vitro almost to the level of KB-3-1 (Pgp-) cells. At the same time, UIC2 alone did not affect the EC50 value of DOX significantly. In xenotransplanted severe combined immunodeficient (SCID) mice co-treated with DOX, UIC2 and CsA, the average weight of Pgp+ tumors was only ∼10% of the untreated control and in 52% of these animals we coul...
Cytometry. Part A : the journal of the International Society for Analytical Cytology, 2004
Lipid rafts are cholesterol- and glycosphingolipid-rich microdomains in the cellular plasma membr... more Lipid rafts are cholesterol- and glycosphingolipid-rich microdomains in the cellular plasma membranes that play critical roles in compartmentalization (concentration, coupling, and isolation) of receptors and signal molecules. Therefore, detecting constitutive or induced raft associations of such proteins is of central interest in cell biology. This has mostly been done with time- and cell-consuming immunobiochemical techniques affected by several sources of artifacts. A flow cytometric analysis of immunocytochemical staining under differential circumstances of detergent treatment offers a new alternative to this method. Membrane microdomains are resistant to nonionic detergents due to extensive, strong interactions between their molecular constituents. We used this feature to develop a rapid flow cytometric assay of differential detergent resistance based on immunocytochemical labeling of extracellular domain epitopes in membrane proteins. Data evaluation is based on comparative de...
Cell Motility and the Cytoskeleton, 2006
A number of cell functions, such as flagellar beating, swimming velocity, acrosome reaction, etc.... more A number of cell functions, such as flagellar beating, swimming velocity, acrosome reaction, etc., are triggered by a Ca 2þ influx across the cell membrane. For appropriate physiological functions, the motile human sperm maintains the intracellular free calcium concentration ([Ca 2þ ] i) at a submicromolar level. The objective of this study was to determine the role of the Na þ /Ca 2þ exchanger (NCX) in the maintenance of [Ca 2þ ] i in human spermatozoa. Spermatozoa maintained in extracellular medium containing !1 lM Ca 2þ exhibited motility similar to that of the control. In addition to several calcium transport mechanisms described earlier, we provide evidence that the NCX plays a crucial role in the maintenance of [Ca 2þ ] i. Three chemically unrelated inhibitors of the NCX (bepridil, DCB (3 0 ,4 0-dichlorobenzamil hydrochloride), and KB-R7943) all blocked human sperm motility in a dose and incubation time dependent manner. The IC 50 values for bepridil, DCB, and KB-R7943 were 16.2, 9.8, and 5.3 lM, respectively. The treatment with the above-mentioned blockers resulted in an elevated [Ca 2þ ] i and a decreased [Na þ ] i. The store-operated calcium channel (SOCC) inhibitor SKF 96365 also blocked the sperm motility (IC 50 ¼ 2.44 lM). The presence of the NCX antigen in the human spermatozoa was proven by flow cytometry, confocal laser scanning microscopy, and immunoblotting techniques. Calcium homeostasis of human spermatozoa is maintained by several transport proteins among which the SOCC and the NCX may play a major role.
![Research paper thumbnail of 18 FDG, [ 18 F]FLT, [ 18 F]FAZA, and 11 C-Methionine Are Suitable Tracers for the Diagnosis and In Vivo Follow-Up of the Efficacy of Chemotherapy by miniPET in Both Multidrug Resistant and Sensitive Human Gynecologic Tumor Xenografts](https://attachments.academia-assets.com/99718805/thumbnails/1.jpg)
](BioMed Research International, 2014
Expression of multidrug pumps including P-glycoprotein (MDR1, ABCB1) in the plasma membrane of tu... more Expression of multidrug pumps including P-glycoprotein (MDR1, ABCB1) in the plasma membrane of tumor cells often results in decreased intracellular accumulation of anticancer drugs causing serious impediment to successful chemotherapy. It has been shown earlier that combined treatment with UIC2 anti-Pgp monoclonal antibody (mAb) and cyclosporine A (CSA) is an effective way of blocking Pgp function. In the present work we investigated the suitability of four PET tumor diagnostic radiotracers including 2-[18F]fluoro-2-deoxy-D-glucose (18FDG),11C-methionine, 3′-deoxy-3′-[18F]fluorothymidine (18F-FLT), and [18F]fluoroazomycin-arabinofuranoside (18FAZA) forin vivofollow-up of the efficacy of chemotherapy in both Pgp positive (Pgp+) and negative (Pgp−) human tumor xenograft pairs raised in CB-17 SCID mice. Pgp+and Pgp−A2780AD/A2780 human ovarian carcinoma and KB-V1/KB-3-1 human epidermoid adenocarcinoma tumor xenografts were used to study the effect of the treatment with an anticancer dru...
International Journal of Molecular Sciences
The human P-glycoprotein (P-gp), a transporter responsible for multidrug resistance, is present i... more The human P-glycoprotein (P-gp), a transporter responsible for multidrug resistance, is present in the plasma membrane’s raft and non-raft domains. One specific conformation of P-gp that binds to the monoclonal antibody UIC2 is primarily associated with raft domains and displays heightened internalization in cells overexpressing P-gp, such as in NIH-3T3 MDR1 cells. Our primary objective was to investigate whether the trafficking of this particular P-gp conformer is dependent on cholesterol levels. Surprisingly, depleting cholesterol using cyclodextrin resulted in an unexpected increase in the proportion of raft-associated P-gp within the cell membrane, as determined by UIC2-reactive P-gp. This increase appears to be a compensatory response to cholesterol loss from the plasma membrane, whereby cholesterol-rich raft micro-domains are delivered to the cell surface through an augmented exocytosis process. Furthermore, this exocytotic event is found to be part of a complex trafficking me...
International Journal of Molecular Sciences
The human ABCB1 (P-glycoprotein, Pgp) protein is an active exporter expressed in the plasma membr... more The human ABCB1 (P-glycoprotein, Pgp) protein is an active exporter expressed in the plasma membrane of cells forming biological barriers. In accordance with its broad substrate spectrum and tissue expression pattern, it affects the pharmacokinetics of numerous chemotherapeutic drugs and it is involved in unwanted drug–drug interactions leading to side effects or toxicities. When expressed in tumor tissues, it contributes to the development of chemotherapy resistance in malignancies. Therefore, the understanding of the molecular details of the ligand–ABCB1 interactions is of crucial importance. In a previous study, we found that quercetin (QUR) hampers both the transport and ATPase activity of ABCB1, while cyandin-3O-sophroside (C3S) stimulates the ATPase activity and causes only a weak inhibition of substrate transport. In the current study, when QUR and C3S were applied together, both a stronger ATPase inhibition and a robust decrease in substrate transport were observed, supporti...
Life, 2021
We studied the effect of different magnitudes (7000 PSI (48.26 MPa), 8000 PSI (55.16 MPa), and 90... more We studied the effect of different magnitudes (7000 PSI (48.26 MPa), 8000 PSI (55.16 MPa), and 9000 PSI (62.05 MPa)) of hydrostatic pressure on the ploidy of pikeperch larvae. Pressure shock was applied 5 min after the fertilization of eggs at a water temperature of 14.8 ± 1 °C. A 7000 PSI pressure shock was applied for 10 or 20 min, while 8000 and 9000 PSI treatments lasted for 10 min. Each treatment with its respective control was completed in triplicate, where different females’ eggs served as a replicate. In the treatment groups exposed to 7000 PSI for 10 min, only diploid and triploid larvae were identified, while 2n/3n mosaic individuals were found after a 20-min exposure to a 7000 PSI pressure shock. The application of 8000 or 9000 PSI pressure shocks resulted in only triploid and mosaic individuals. Among larvae from eggs treated with 8000 PSI, three mosaic individuals with 2n/3n karyotype were identified (4.0 ± 6.9%), while a single (2.0 ± 3.5%) 1n/3n mosaic individual was ...
Biophysical Journal, 2017
Cancer detection and prevention, 2000
P-glycoprotein (P-gp) acts as an active efflux mechanism for a large number of cytostatics and se... more P-glycoprotein (P-gp) acts as an active efflux mechanism for a large number of cytostatics and seems to be involved in the frequent failure of cancer chemotherapy. The molecular events of substrate recognition and transport still are not understood completely. We show here that the percentage of P-gp epitopes available for labeling with UIC2 monoclonal antibody is increased significantly after methanol permeabilization/fixation of cells. At the same time, binding of the MRK16 and 4E3 anti-P-gp antibodies is changed only moderately. Confocal microscopical images of UIC2-PE-labeled cells show that the epitopes becoming available after fixation are situated mainly in the plasma membrane. Thus, only a minority of P-gp molecules are accessible for UIC2 in the cell membrane of live cells, and methanol treatment can expose a large pool of previously plasma membrane-embedded, cryptic UIC2 epitopes. The UIC2-reactive P-gp molecules do not appear to be sequestered spatially, as suggested by t...
ABCG2 is an exporter type ABC protein that can expel numerous chemically unrelated xeno- and endo... more ABCG2 is an exporter type ABC protein that can expel numerous chemically unrelated xeno- and endobiotics from cells. When expressed in tumor cells or tumor stem cells, ABCG2 confers multidrug resistance, contributing to the failure of chemotherapy.Molecular details orchestrating substrate translocation and ATP hydrolysis remain elusive. Here we present methods to concomitantly investigate substrate and nucleotide binding by ABCG2 in cells. Using the conformation-sensitive antibody 5D3, we show that the switch from the inward-facing (IF) to the outward-facing (OF) conformation of ABCG2 is induced by nucleotide binding. IF-OF transition is facilitated by substrates, and hindered by the inhibitor Ko143. Direct measurements of 5D3 and substrate binding to ABCG2 indicate that the high-to-low affinity switch of the drug binding site coincides with the transition from the IF to the OF conformation. Low substrate binding persists in the post-hydrolysis state, supporting that dissociation of...
PLOS Genetics, 2020
Several ABC exporters carry a degenerate nucleotide binding site (NBS) that is unable to hydrolyz... more Several ABC exporters carry a degenerate nucleotide binding site (NBS) that is unable to hydrolyze ATP at a rate sufficient for sustaining transport activity. A hallmark of a degenerate NBS is the lack of the catalytic glutamate in the Walker B motif in the nucleotide binding domain (NBD). The multidrug resistance transporter ABCB1 (P-glycoprotein) has two canonical NBSs, and mutation of the catalytic glutamate E556 in NBS1 renders ABCB1 transport-incompetent. In contrast, the closely related bile salt export pump ABCB11 (BSEP), which shares 49% sequence identity with ABCB1, naturally contains a methionine in place of the catalytic glutamate. The NBD-NBD interfaces of ABCB1 and ABCB11 differ only in four residues, all within NBS1. Mutation of the catalytic glutamate in ABCB1 results in the occlusion of ATP in NBS1, leading to the arrest of the transport cycle. Here we show that despite the catalytic glutamate mutation (E556M), ABCB1 regains its ATP-dependent transport activity, when three additional diverging residues are also replaced. Molecular dynamics simulations revealed that the rescue of ATPase activity is due to the modified geometry of NBS1, resulting in a weaker interaction with ATP, which allows the quadruple mutant to evade the conformationally locked pre-hydrolytic state to proceed to ATP-driven transport. In summary, we show that ABCB1 can be transformed into an active transporter with only one functional catalytic site by preventing the formation of the ATP-locked pre-hydrolytic state in the non-canonical site.
European journal of pharmaceutical sciences : official journal of the European Federation for Pharmaceutical Sciences, Jan 6, 2015
In vivo detection of the emergence of P-glycoprotein (Pgp) mediated multidrug resistance in tumor... more In vivo detection of the emergence of P-glycoprotein (Pgp) mediated multidrug resistance in tumors could be beneficial for patients treated with anticancer drugs. PET technique in combination with appropriate radiotracers could be the most convenient method for detection of Pgp function. Rhodamine derivatives are validated fluorescent probes for measurement of mitochondrial membrane potential and also Pgp function. The aim of this study was to investigate whether 2'[(18)F]-fluoroethylrhodamine B ((18)FRB) a halogenated rhodamine derivative previously synthesized for PET assessment of myocardial perfusion preserved its Pgp substrate character. ATPase assay as well as accumulation experiments carried out using Pgp(+) and Pgp(-) human gynecologic (A2780/A2780(AD) and KB-3-1/KB-V1) and a mouse fibroblast cell pairs (NIH 3T3 and NIH 3T3 MDR1) were applied to study the interaction of (18)FRB with Pgp. ATPase assay proved that (18)FRB is a high affinity substrate of Pgp. Pgp(-) cells a...
European journal of pharmaceutical sciences : official journal of the European Federation for Pharmaceutical Sciences, Jan 20, 2014
2-[(18)F]fluoro-2-deoxy-d-glucose ((18)FDG) is a tumor diagnostic radiotracer of great importance... more 2-[(18)F]fluoro-2-deoxy-d-glucose ((18)FDG) is a tumor diagnostic radiotracer of great importance in both diagnosing primary and metastatic tumors and in monitoring the efficacy of the treatment. P-glycoprotein (Pgp) is an active transporter that is often expressed in various malignancies either intrinsically or appears later upon disease progression or in response to chemotherapy. Several authors reported that the accumulation of (18)FDG in P-glycoprotein (Pgp) expressing cancer cells (Pgp(+)) and tumors is different from the accumulation of the tracer in Pgp nonexpressing (Pgp(-)) ones, therefore we investigated whether (18)FDG is a substrate or modulator of Pgp pump. Rhodamine 123 (R123) accumulation experiments and ATPase assay were used to detect whether (18)FDG is substrate for Pgp. The accumulation and efflux kinetics of (18)FDG were examined in two different human gynecologic (A2780/A2780AD and KB-3-1/KB-V1) and a mouse fibroblast (3T3 and 3T3MDR1) Pgp(+) and Pgp(-) cancer c...
PloS one, 2014
P-glycoprotein (Pgp) extrudes a large variety of chemotherapeutic drugs from the cells, causing m... more P-glycoprotein (Pgp) extrudes a large variety of chemotherapeutic drugs from the cells, causing multidrug resistance (MDR). The UIC2 monoclonal antibody recognizes human Pgp and inhibits its drug transport activity. However, this inhibition is partial, since UIC2 binds only to 10-40% of cell surface Pgps, while the rest becomes accessible to this antibody only in the presence of certain substrates or modulators (e.g. cyclosporine A (CsA)). The combined addition of UIC2 and 10 times lower concentrations of CsA than what is necessary for Pgp inhibition when the modulator is applied alone, decreased the EC50 of doxorubicin (DOX) in KB-V1 (Pgp+) cells in vitro almost to the level of KB-3-1 (Pgp-) cells. At the same time, UIC2 alone did not affect the EC50 value of DOX significantly. In xenotransplanted severe combined immunodeficient (SCID) mice co-treated with DOX, UIC2 and CsA, the average weight of Pgp+ tumors was only ∼10% of the untreated control and in 52% of these animals we coul...
Cytometry. Part A : the journal of the International Society for Analytical Cytology, 2004
Lipid rafts are cholesterol- and glycosphingolipid-rich microdomains in the cellular plasma membr... more Lipid rafts are cholesterol- and glycosphingolipid-rich microdomains in the cellular plasma membranes that play critical roles in compartmentalization (concentration, coupling, and isolation) of receptors and signal molecules. Therefore, detecting constitutive or induced raft associations of such proteins is of central interest in cell biology. This has mostly been done with time- and cell-consuming immunobiochemical techniques affected by several sources of artifacts. A flow cytometric analysis of immunocytochemical staining under differential circumstances of detergent treatment offers a new alternative to this method. Membrane microdomains are resistant to nonionic detergents due to extensive, strong interactions between their molecular constituents. We used this feature to develop a rapid flow cytometric assay of differential detergent resistance based on immunocytochemical labeling of extracellular domain epitopes in membrane proteins. Data evaluation is based on comparative de...
Cell Motility and the Cytoskeleton, 2006
A number of cell functions, such as flagellar beating, swimming velocity, acrosome reaction, etc.... more A number of cell functions, such as flagellar beating, swimming velocity, acrosome reaction, etc., are triggered by a Ca 2þ influx across the cell membrane. For appropriate physiological functions, the motile human sperm maintains the intracellular free calcium concentration ([Ca 2þ ] i) at a submicromolar level. The objective of this study was to determine the role of the Na þ /Ca 2þ exchanger (NCX) in the maintenance of [Ca 2þ ] i in human spermatozoa. Spermatozoa maintained in extracellular medium containing !1 lM Ca 2þ exhibited motility similar to that of the control. In addition to several calcium transport mechanisms described earlier, we provide evidence that the NCX plays a crucial role in the maintenance of [Ca 2þ ] i. Three chemically unrelated inhibitors of the NCX (bepridil, DCB (3 0 ,4 0-dichlorobenzamil hydrochloride), and KB-R7943) all blocked human sperm motility in a dose and incubation time dependent manner. The IC 50 values for bepridil, DCB, and KB-R7943 were 16.2, 9.8, and 5.3 lM, respectively. The treatment with the above-mentioned blockers resulted in an elevated [Ca 2þ ] i and a decreased [Na þ ] i. The store-operated calcium channel (SOCC) inhibitor SKF 96365 also blocked the sperm motility (IC 50 ¼ 2.44 lM). The presence of the NCX antigen in the human spermatozoa was proven by flow cytometry, confocal laser scanning microscopy, and immunoblotting techniques. Calcium homeostasis of human spermatozoa is maintained by several transport proteins among which the SOCC and the NCX may play a major role.
BioMed Research International, 2014
Expression of multidrug pumps including P-glycoprotein (MDR1, ABCB1) in the plasma membrane of tu... more Expression of multidrug pumps including P-glycoprotein (MDR1, ABCB1) in the plasma membrane of tumor cells often results in decreased intracellular accumulation of anticancer drugs causing serious impediment to successful chemotherapy. It has been shown earlier that combined treatment with UIC2 anti-Pgp monoclonal antibody (mAb) and cyclosporine A (CSA) is an effective way of blocking Pgp function. In the present work we investigated the suitability of four PET tumor diagnostic radiotracers including 2-[18F]fluoro-2-deoxy-D-glucose (18FDG),11C-methionine, 3′-deoxy-3′-[18F]fluorothymidine (18F-FLT), and [18F]fluoroazomycin-arabinofuranoside (18FAZA) forin vivofollow-up of the efficacy of chemotherapy in both Pgp positive (Pgp+) and negative (Pgp−) human tumor xenograft pairs raised in CB-17 SCID mice. Pgp+and Pgp−A2780AD/A2780 human ovarian carcinoma and KB-V1/KB-3-1 human epidermoid adenocarcinoma tumor xenografts were used to study the effect of the treatment with an anticancer dru...