Search

Your search keyword '"Kalsi, K"' showing total 117 results
Start Over Author "Kalsi, K"
117 results on '"Kalsi, K"'

8. Abstract 3064: Epigenetic manipulation can sensitize AML cells to differentiate with ATRA

Author

Heidi J. Gill Super, Bikalpa Ghimire, Edjay Ralph A. Hernandez, and Kalsi K. Heimdal

Subjects
Cancer Research, Cell cycle checkpoint, biology, Chemistry, medicine.disease_cause, chemistry.chemical_compound, Histone, Oncology, Acetylation, Cancer cell, Cancer research, biology.protein, medicine, Histone deacetylase, Carcinogenesis, Chromatin immunoprecipitation, Sulforaphane
Abstract

Human acute myeloid leukemia (AML), the most common type of acute leukemia, has approximately eight subtypes, many of which have poor prognosis. Most of these subtypes are associated with specific, recurrent chromosome translocations. These translocations result in fusion genes, which encode oncoproteins that block differentiation and promote proliferation of immature cells. The Myeloid Lymphoid Leukemia gene (MLL) is frequently involved in these translocations, and is considered a driver of the AML. Differentiation promoting drugs, such as all-trans-retinoic acid (ATRA) are an attractive alternative to cytotoxic chemotherapy, but few types of AML, other than acute promyelocytic leukemia (APL), respond to ATRA. We hypothesize that specific genes must be activated or inhibited in AML for drugs like ATRA to induce differentiation, and that gene activation or inhibition may be the result of specific epigenetic modification. We also hypothesize that AML with different genetic alterations may respond differently to specific epigenetic inhibitors. Our initial studies have focused on two MLL-driven AML cell lines, MV4;11 and THP-1, showing translocations t(4;11) and t(9;11), respectively, and one non-MLL related AML cell line, U937. MV4;11, THP-1, and U937 were treated with specific epigenetic modifiers, including tranylcypromine (TCP), an inhibitor of histone demethylase KMD1A/LSD1, N-acetyl-dinaline (CI-994), a general histone deacetylase inhibitor, and 3-deazaneplanocin A (DZNep), a S-adenosylhomocystein hydrolase inhibitor that depletes EZH2 and thus its associated H3K27me3 activity. Evidence for differentiation was noted in a variety of assays, including reduced cell proliferation as measured directly and by MTT assay, upregulation of myeloid-specific cell surface markers such as CD11b as measured by fluorescence-activated cell sorting (FACS), myeloid-related nuclear morphological changes noted with cytospin analysis of cells, and decreased AML-associated gene expression with qPCR. All three drugs seemed to sensitize U937 and THP-1 cells to differentiate when treated with ATRA. MV4;11 cells were sensitized to differentiate by CI-994 and DZNep with or without ATRA, although there was no indication of CD11b upregulation. However, MV4;11 was not sensitized by TCP to differentiate with or without ATRA. These experiments suggest epigenetic inhibitors may increase sensitivity to ATRA differentiation therapy, but since the two MLL cell lines responded differently the response may still be dependent on the specific MLL partner gene driving the AML. Citation Format: Kalsi Heimdal, Bikalpa Ghimire, Edjay Ralph Hernandez, Heidi J. Gill Super. Epigenetic manipulation can sensitize AML cells to differentiate with ATRA [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3064.

Published
2019

10. Abstract 870: Effects of epigenetic modifier inhibitors on AML cell sensitivity to differentiation therapy

Author

Heidi J. Gill Super, Edjay Ralph A. Hernandez, and Kalsi K. Heimdal

Subjects
Cell sensitivity, Cancer Research, Oncology, Epigenetic modifier, business.industry, Differentiation therapy, Cancer research, Medicine, business
Abstract

Human acute myeloid leukemia (AML), the most common type of acute leukemia, has approximately eight subtypes, many of which have poor prognosis. Most of these subtypes are associated with specific, recurrent chromosome translocations. These translocations result in fusion genes, which encode oncoproteins that block differentiation and promote proliferation of immature cells. The Myeloid Lymphoid Leukemia gene (MLL) is frequently involved in these translocations, and is considered a driver of the AML. Differentiation promoting drugs, such as all-trans-retinoic acid (ATRA) are an attractive alternative to cytotoxic chemotherapy, but few types of AML, other than acute promyelocytic leukemia (APL), respond to ATRA. We hypothesize that specific genes must be activated or inhibited in AML for drugs like ATRA to induce differentiation, and that gene activation or inhibition may be the result of specific epigenetic modification. We also hypothesize that AML with different genetic alterations may respond differently to specific epigenetic inhibitors. Our initial studies have focused on one AML cell line, MV4;11, with alterations in the MLL gene, and one non-MLL related AML cell line, U937. MV4;11 and U937 were treated with specific epigenetic modifiers, including tranylcypromine (TCP), an inhibitor of histone demethylase KMD1A/LSD1, and CI-994, a general histone deacetylase inhibitor. Evidence for differentiation was noted in a variety of assays, including reduced cell proliferation as measured directly and by MTT assay, upregulation of myeloid-specific cell surface markers such as CD11b as measured by fluorescence-activated cell sorting (FACS), and myeloid-related nuclear morphological changes noted with cytospin analysis of cells. Both CI-994 and TCP seemed to sensitize U937 cells to differentiate when treated with ATRA as measured by all indicators of differentiation. MV4;11 cells were sensitized to differentiation by CI-994 with or without ATRA, although there was no indication of CD11b upregulation. However, MV4;11 was not sensitized by TCP to differentiate with ATRA. These experiments suggest epigenetic inhibitors may increase sensitivity to differentiation therapy, but that the response may still be dependent on the specific genetic alteration driving the AML. Our studies suggest that in MLL-driven leukemia, the MLL fusion oncoprotein may override genetic manipulation resulting from treatment with epigenetic inhibitors, preventing differentiation by ATRA. Citation Format: Kalsi K. Heimdal, Edjay Ralph A. Hernandez, Heidi J. Gill Super. Effects of epigenetic modifier inhibitors on AML cell sensitivity to differentiation therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 870.

Published
2018

11. Exposure to human blood inactivates swine ecto-5'-nucleotidase

Author

Khalpey Z., Kalsi K. K., Yuen A., Karbowska J., Kochan Z., Slominska E. M., Maccherini M., Batten P., Lavitrano M., Yacoub M. H., Smolenski R. T., FORNI, MONICA, BACCI, MARIA LAURA, Khalpey Z., Kalsi K.K., Yuen A., Karbowska J., Kochan Z., Slominska E.M., Forni M., Bacci M.L., Maccherini M., Batten P., Lavitrano M., Yacoub M.H., and Smolenski R.T.

Abstract

Ecto-5'-nucleotidase (E5'N) is an extracellular enzyme forming anti-inflammatory and immunosuppressive adenosine. We evaluated whether confrontation of pig heart and endothelial cells with human blood changes the activity of E5'N. Pig hearts were perfused ex vivo with fresh human blood for 4 h. Pig aortic endothelial cells (PAEC) were incubated in vitro with human plasma for 3 h. Ex vivo perfusion of pig heart with fresh human blood resulted in a decrease in E5'N activity to 62% and 61% of initial in wild-type and transgenic pig hearts, respectively. PAEC activity of E5'N decreased to 71% and 50% of initial after 3 h exposure to heat-inactivated and active complement human plasma, respectively, while it remained constant in controls. Pig heart activity of E5'N decreased following exposure to human blood, which may affect adenosine production and exacerbate hyperacute and vascular rejection.

Published
2005

12. Mammalian mismatches in nucleotide metabolism: implications for xenotransplantation

Author

Khalpey, Z, Yuen, A, Lavitrano, M, Mcgregor, C, Kalsi, K, Yacoub, M, Smolenski, R, Yuen, AHY, McGregor, CGA, Kalsi, KK, Yacoub, MH, Smolenski, RT, LAVITRANO, MARIALUISA, Khalpey, Z, Yuen, A, Lavitrano, M, Mcgregor, C, Kalsi, K, Yacoub, M, Smolenski, R, Yuen, AHY, McGregor, CGA, Kalsi, KK, Yacoub, MH, Smolenski, RT, and LAVITRANO, MARIALUISA

Abstract

Acute humoral rejection (AHR) limits the clinical application of animal organs for xenotransplantation. Mammalian disparities in nucleotide metabolism may contribute significantly to the microvascular component in AHR; these, however remain ill-defined. We evaluated the extent of species-specific differences in nucleotide metabolism. HPLC analysis was performed on venous blood samples (nucleotide metabolites) and heart biopsies (purine enzymes) from wild type mice, rats, pigs, baboons, and human donors. Ecto-5'-nucleotidase (E5'N) activities were 4-fold lower in pigs and baboon hearts compared to human and mice hearts while rat activity was highest. Similar differences between pigs and humans were also observed with kidneys and endothelial cells. More than 10-fold differences were observed with other purine enzymes. AMP deaminase (AMPD) activity was exceptionally high in mice but very low in pig and baboon hearts. Adenosine deaminase (ADA) activity was highest in baboons. Adenosine kinase (AK) activity was more consistent across different species. Pig blood had the highest levels of hypoxanthine, inosine and adenine. Human blood uric acid concentration was almost 100 times higher than in other species studied. We conclude that species-specific differences in nucleotide metabolism may affect compatibility of pig organs within a human metabolic environment. Furthermore, nucleotide metabolic mismatches may affect clinical relevance of animal organ transplant models. Supplementation of deficient precursors or application of inhibitors of nucleotide metabolism (e.g., allopurinol) or transgenic upregulation of E5'N may overcome some of these differences.

Published
2007

13. Differences in activities of the enzymes of nucleotide metabolism and its implications for cardiac xenotransplantation

Author

Yuen, A, Khalpey, Z, Lavitrano, M, Mcgregor, C, Kalsi, K, Yacoub, M, Smolenski, R, Yuen, AHY, McGregor, CGA, Kalsi, KK, Yacoub, MH, Smolenski, RT, LAVITRANO, MARIALUISA, Yuen, A, Khalpey, Z, Lavitrano, M, Mcgregor, C, Kalsi, K, Yacoub, M, Smolenski, R, Yuen, AHY, McGregor, CGA, Kalsi, KK, Yacoub, MH, Smolenski, RT, and LAVITRANO, MARIALUISA

Abstract

Xenotransplantation is one be possible solution for a severe shortage of human organs available for transplantation. However, only a few studies addressed metabolic compatibility of transplanted animal organs. Our aim was to compare activities of adenosine metabolizing enzymes in the heart of different species that are relevant to clinical or experimental xenotransplantation. We noted fundamental differences: ecto-5' nucleotidease ( E5'N) activity was 4-fold lower in pig and baboon hearts compared to the human hearts while mouse activity was compatible with human and rat activity was three times higher than human. There also were significant differences in AMP-deaminase ( AMPD), adenosine deaminase ( ADA) and purine nucleoside phosphorylase ( PNP) activities. We conclude that differences in nucleotide metabolism may contribute to organ dysfunction after xenotransplantation.

Published
2006

14. Exposure to human blood inactivates swine endothelial ecto-5 '-nucleotidase

Author

Khalpey, Z, Kalsi, K, Yuen, A, Karbowska, J, Kochan, Z, Slominska, E, Forni, M, Bacci, M, Macherini, M, Batten, P, Lavitrano, M, Yacoub, M, Smolenski, R, Slominska, EM, Yacoub, MH, Smolenski, RT, LAVITRANO, MARIALUISA, Khalpey, Z, Kalsi, K, Yuen, A, Karbowska, J, Kochan, Z, Slominska, E, Forni, M, Bacci, M, Macherini, M, Batten, P, Lavitrano, M, Yacoub, M, Smolenski, R, Slominska, EM, Yacoub, MH, Smolenski, RT, and LAVITRANO, MARIALUISA

Abstract

Ecto-5'-nucleotidase (E5'N) is an extracellular enzyme forming anti-inflammatory and immunosuppressive adenosine. We evaluated whether confrontation of pig heart and endothelial cells with human blood changes the activity of E5'N. Pig hearts were perfused ex vivo with fresh human blood for 4 h. Pig aortic endothelial cells (PAEC) were incubated in vitro with human plasma for 3 h. Ex vivo perfusion of pig heart with fresh human blood resulted in a decrease in E5'N activity to 62% and 61% of initial in wild-type and transgenic pig hearts, respectively. PAEC activity of E5'N decreased to 71% and 50% of initial after 3 h exposure to heat-inactivated and active complement human plasma, respectively, while it remained constant in controls. Pig heart activity of E5'N decreased following exposure to human blood, which may affect adenosine production and exacerbate hyperacute and vascular rejection.

Published
2005

15. Loss of ecto-5 ' nucleotidase from porcine endothelial cells after exposure to human blood: Implications for xenotransplantation

Author

Khalpey, Z, Yuen, A, Kalsi, K, Kochan, Z, Karbowska, J, Slominska, E, Forni, M, Macherini, M, Bacci, M, Batten, P, Lavitrano, M, Yacoub, M, Smolenski, R, Yuen, AH, Kalsi, KK, Slominska, EM, Bacci, ML, Yacoub, MH, Smolenski, RT, LAVITRANO, MARIALUISA, Khalpey, Z, Yuen, A, Kalsi, K, Kochan, Z, Karbowska, J, Slominska, E, Forni, M, Macherini, M, Bacci, M, Batten, P, Lavitrano, M, Yacoub, M, Smolenski, R, Yuen, AH, Kalsi, KK, Slominska, EM, Bacci, ML, Yacoub, MH, Smolenski, RT, and LAVITRANO, MARIALUISA

Abstract

The endothelial cell Surface expression of ecto-5-nucleotidase (E5'N, CD73) is thought to be essential for the extracellular formation of cytoprotective, anti-thrombotic and immunosuppressive adenosine. Decreased E5'N activity may play a role in xenograft acute vascular rejection, preventing accommodation and tolerance mechanisms. We investigated the extent of changes in E5'N activity and other enzymes of purine metabolism in porcine hearts or endothelial cells when exposed to human blood or plasma and studied the role of humoral immunity in this context. Pig hearts, wild type (WT, n = 6) and transgenic (T, n = 5) for human decay accelerating factor (hDAF), were perfused ex vivo with fresh human blood for 4 h. Pig aortic endothelial cells (PAEC) were exposed for 3 h to autologous porcine plasma (PP), normal (NHP) or heat inactivated human plasma (HHP), with and without C1-inhibitor. Enzyme activities were measured in heart or endothelial cell homogenates with an HPLC based procedure. The baseline activity of E5'N in WT and T porcine hearts were 6.60 +/- 0.33 nmol/min/mg protein and 8.54 +/- 2.10 nmol/min/mg protein respectively (P < 0.01). Ex vivo perfusion of pig hearts with fresh human blood for 4 h resulted in a decrease in E5'N activity to 4.01 +/- 0.32 and 4.52 +/- 0.52 nmol/min/mg protein (P < 0.001) in WT and T hearts respectively, despite attenuation of hyperacute rejection in transgenic pigs. The initial PAEC activity of E5'N was 9.10 +/- 1.40 nmol/min/mg protein. Activity decreased to 6.76 +/- 0.57 and 4.58 +/- 0.47 mmol/min/mg protein (P < 0.01) after 3 It exposure of HHP and NHP respectively (P < 0.05), whereas it remained unchanged at 9.62 +/- 0.88 nmol/min/mg protein when incubated with PP controls. Cl-inhibitor partially preserved UN activity, similar to the effect of HHP. Adenosine deaminase, adenosine kinase and AMP deaminase (other enzymes of purine metabolism) showed a downward trend in activity, but none were statistically significant. We demonst

Published
2005

16. Expression of human ecto-5′-nucleotidase in pig endothelium increases adenosine production and protects from NK cell-mediated lysis

Author

Osborne, F, Kalsi, K, Lawson, C, Lavitrano, M, Yacoub, M, Rose, M, Smolenski, R, Osborne, FN, Kalsi, KK, Yacoub, MH, Rose, ML, Smolenski, RT, LAVITRANO, MARIALUISA, Osborne, F, Kalsi, K, Lawson, C, Lavitrano, M, Yacoub, M, Rose, M, Smolenski, R, Osborne, FN, Kalsi, KK, Yacoub, MH, Rose, ML, Smolenski, RT, and LAVITRANO, MARIALUISA

Abstract

Ecto-5'-nucleotidase (E5'N) is an endothelial surface enzyme that controls conversion of extracellular nucleotides into immunosuppressive adenosine. We evaluated whether expression of human E5'N on pig endothelial cells (EC) attenuates human NK cell-mediated cytotoxicity. A pig EC line was stably transfected with human E5'N and human NK cell adhesion and cytotoxicity toward pig EC cultures was measured by flow cytometry and intracellular enzyme release. E5'N activity in pig EC lysates increased from 0.68 &PLUSMN; 0.07 to 1013 &PLUSMN; 293 nmol/min/mg protein, whilst the rate of AMP to adenosine metabolism by intact cells increased from 0.37 &PLUSMN; 0.05 to > 300 nmol/min/mg protein in non-transfected and transfected cells, respectively. The rate of adenosine production in transfected cells increased also with ATP as the extracellular substrate. Cytotoxicity of human NK cells was reduced from 10.7 &PLUSMN; 0.4% and 11.1 &PLUSMN; 1.1% with non-transfected pig EC to 5.2 &PLUSMN; 0.2% and 5.0 &PLUSMN; 0.2% in transfected cells with 50 ¿ M and 250 ¿ M AMP, respectively. Reduction of cytotoxicity in E5'N-transfected EC was abolished by the E5'N inhibitor and was mimicked in non-transfected EC by the addition of adenosine, demonstrating the key role of adenosine produced by E5'N in inhibiting NK cell cytotoxicity. We suggest that overexpression of E5'N in EC of transgenic pigs is a possible strategy to ameliorate rejection after xeno-transplantation.

Published
2005

25. Exposure to Human Blood Inactivates Swine Endothelial Ecto-5'-Nucleotidase

Author

Khalpey, Z., primary, Kalsi, K., additional, Yuen, A., additional, Karbowska, J., additional, Kochan, Z., additional, Slominska, E. M., additional, Forni, M., additional, Bacci, M., additional, Macherini, M., additional, Batten, P., additional, Lavitrano, M., additional, Yacoub, M. H., additional, and Smolenski, R. T., additional

Published
2005
Full Text
View/download PDF

47. Influence of heat stress on myocardial metabolism and functional recovery after cardioplegic arrest: a 31P N.M.R study.

Author

Jayakumar, J, Smolenski, R T, Gray, C C, Goodwin, A T, Kalsi, K, Amrani, M, and Yacoub, M H

Abstract

Heat stress and induction of heat shock proteins confer protection against myocardial ischemia-reperfusion injury; however the precise mechanisms of this effect remain unknown. We investigated the influence of heat stress on metabolic and functional recovery after cardioplegic arrest, in a protocol mimicking clinical donor heart preservation.

Published
1998
Full Text
View/download PDF

49. Physiological heating and cooling does not stimulate temperature-dependant ATP release from human vascular endothelial cells: signalling implications for the regulation of vascular tone.

Author

Kalsi, K. K., Rakobowchuk, M., and González-Alonso, J.

Subjects
*ADENOSINE triphosphate, *ENDOTHELIAL cells
Abstract

An abstract of the article "Physiological heating and cooling does not stimulate temperature-dependant ATP release from human vascular endothelial cells: signalling implications for the regulation of vascular tone" by K. K. Kalsi and colleagues is presented.

Published
2014

50. Blood temperature influences erythrocyte ATP release and muscle blood flow in human limbs.

Author

Kalsi, K. K., Chiesa, S. T., Trangmar, S. J., and González-Alonso, J.

Subjects
*PHYSIOLOGICAL effects of temperature, *MUSCLE physiology, *ADENOSINE triphosphate
Abstract

Human limb muscle and skin perfusion alters with changes in tissue temperature evoked by heating or cooling and these processes may involve temperature sensitive regulatory mechanisms. We have previously shown that passive heating and exercise increase limb tissue blood flow in humans in association with the increases in muscle temperature and plasma adenosine 5'-triphosphate concentration [ATP] (1,2). Reduced haemoglobin O2 saturation is thought to be the main stimulus for erythrocyte ATP release in the muscle microcirculation (3,4). Recent evidence, however, suggests that temperature is another potent stimulus. Here we tested the hypothesis that the release of the vasodilator mediator ATP from human erythrocytes is sensitive to physiological reductions and increases in blood temperature independently of oxygenation induced ATP release in the human forearm circulation. To accomplish this aim, we measured forearm blood flow (FBF; Doppler ultrasound), deep venous blood temperature (Tb), retrograde venous plasma [ATP], blood gas parameters and calculated forearm vascular conductance (FVC) in the experimental and the control contralateral forearm in 7 males (19 ± 2 years) during 1 hour of passive heating using a water perfused cuff and 1 hour of passive cooling using ice with 1 hour of rest in between. All data are mean ± SEM and were compared with ANOVA and Pearson correlation (SPSS). With heating T increased from 34.0 ± 0.5 to 36.8 ± 0.1°C (p<0.05) while with cooling Tb decreased from 34.4 ± 0.4 to 29.1 ± 0.7°C (p<0.05). Plasma [ATP] doubled with heating from 0.21 ± 0.03 to 0.43 ± 0.05 µmol.l-1 (p<0.05) but did not change with cooling remaining at 0.23 ± 0.03-1 µmol.l-1 similar to values in the control forearm. FBF progressively and significantly increased with heating from 124 ± 11 to 418 ± 10 ml.min-1 (p<0.05) and decreased with cooling from 121 ± 11 to 90 ± 14 ml.min-1 (p<0.05). Similar significant responses were observed with FVC, indicating that flow changes with heating and cooling were due to vasodilatation and vasoconstriction, respectively. In contrast, control forearm values for Tb, [ATP], FBF and FVC were unchanged throughout the study. During heating and cooling, FBF and FVC were exponentially correlated to Tb (R² = 0.86 and 0.87, respectively; p<0.01) and [ATP] (both R² = 0.85; p<0.01). Contrary to the reported involvement of the O2 saturation pathway, plasma [ATP] remained unchanged during cooling despite decreasing O2 saturation from 62 ± 4 to 35 ± 4% (p<0.05) but increased with heating when O2 saturation was elevated from 59 ± 6 to 82 ± 4% (p<0.05). These findings suggest that ATP from erythrocytes may be an important mechanism regulating human limb muscle and skin perfusion in conditions that alter blood and tissue temperature. Furthermore, it seems that temperature works through a distinct pathway to that sensitive to blood oxygenation. [ABSTRACT FROM AUTHOR]

Published
2013

Catalog

Books, media, physical & digital resources
See catalog results