Berna Demircan | Istanbul Medeniyet University (original) (raw)

Papers by Berna Demircan

Research paper thumbnail of Effects of indomethacin, celecoxib and meloxicam on glutathione, malondialdehyde and myeloperoxidase in rat gastric tissue

Pain Clinic, 2005

Abstract: In the present study, we examined the effects of indomethacin, celecoxib and meloxicam ... more Abstract: In the present study, we examined the effects of indomethacin, celecoxib and meloxicam on the stomach and on levels of glutathione (GSH), malondialdehyde (MDA) and activity of myeloperoxidase (MPO) in gastric tissues of rats. The ulcer area was 31.1±10.7 ...

Research paper thumbnail of ANTI-INFLAMMATORY EFFECTS OF SELECTIVE COX2 INHIBITORS

In this study, effects of rofecoxib, celecoxib, nimesulide on the acute phase of inflammation wer... more In this study, effects of rofecoxib, celecoxib, nimesulide on the acute phase of inflammation were studied in the carrageenan-induced paw edema model and their influence on the chronic phase of inflammation was evaluated in the cotton pellet granuloma tests. Additionally, effects of these drugs on capillary vascular permeability were examined in the hyaluronidase test and were compared with that of indomethacin (nonselective COX inhibitor).

Research paper thumbnail of Anti-inflammatory and side effects of cyclooxygenase inhibitors

Nonsteroidal anti-inflammatory drugs (NSAIDs) are the most commonly used drugs in inflammatory di... more Nonsteroidal anti-inflammatory drugs (NSAIDs) are the most commonly used drugs in inflammatory diseases, since they are effective in management of pain, fever, redness, edema arising as a consequence of inflammatory mediator release. Studies have shown that both therapeutic and side effects of NSAIDs are dependent on cyclooxygenase (COX) inhibition. COX isoforms have been named constitutive (COX-1) and inducible (COX-2). COX-1 catalyzes formation of cytoprotective prostaglandins in thrombocytes, vascular endothelium, stomach mucosa, kidneys, pancreas, Langerhans islets, seminal vesicles, and brain. Induction of COX-2 by various growth factors, proinflammatory agents, endotoxins, mitogens, and tumor agents indicates that this isoform may have a role in induction of pathological processes, such as inflammation. It is well known that therapy with COX inhibitors is associated with a number of side effects including gastrointestinal erosions, and renal and hepatic insufficiency. Such critical adverse reactions are mostly dependent on COX-1 inhibition. As a result of research focused on reduction of the adverse effects of NSAIDs, selective COX-2 inhibitors, such as celecoxib and rofecoxib have been developed. However, many data demonstrate that mechanisms of action of these drugs are multidirectional and complex. These drugs or their derivatives, which belong to the same group, have distinct pharmacological effects, side effects and potencies which implies that there may be more than two, five or even tens of COX isoforms.

Research paper thumbnail of EFFECTS OF ENDURANCE TRAINING ON ANTIOXIDANT DEFENSE MECHANISMS AND LIPID PEROXIDATION IN TESTIS OF RATS

Systems Biology in Reproductive Medicine, 2006

Research paper thumbnail of Maternal Serum Interleukin10, Interleukin2 and Interleukin6 in Pre-Eclampsia and Eclampsia

American Journal of Reproductive Immunology, 2007

ProblemThe aim of the study was to investigate and compare the concentrations of interleukin (IL)... more ProblemThe aim of the study was to investigate and compare the concentrations of interleukin (IL)-2, IL-6, and IL-10 in serum of women with mild pre-eclampsia, severe pre-eclampsia, eclampsia, and normotensive pregnancy.The aim of the study was to investigate and compare the concentrations of interleukin (IL)-2, IL-6, and IL-10 in serum of women with mild pre-eclampsia, severe pre-eclampsia, eclampsia, and normotensive pregnancy.Method of studyA total of 69 consecutive cases, 38 mild pre-eclampsia, 20 severe pre-eclampsia, 11 eclampsia, and 20 normotensive controls were included in this study. Serum IL-2, IL-6, and IL-10 levels were determined using enzyme-linked immunosorbent assay method.A total of 69 consecutive cases, 38 mild pre-eclampsia, 20 severe pre-eclampsia, 11 eclampsia, and 20 normotensive controls were included in this study. Serum IL-2, IL-6, and IL-10 levels were determined using enzyme-linked immunosorbent assay method.ResultsGestational age (P = 0.210) and body mass index (P = 0.214) between the groups were similar. The mean concentration of serum IL-2 and IL-6 were not different between the groups (P = 0.261, P = 0.141 respectively). The median concentrations of serum IL-10 in patients with mild and severe pre-eclampsia were similar (P < 0.282) and was significantly lower than those of controls (P < 0.001) and patients with eclampsia (P < 0.001). In patients with eclampsia, the median concentration of IL-10 was significantly higher than that of all other groups (P < 0.001 for each comparison).Gestational age (P = 0.210) and body mass index (P = 0.214) between the groups were similar. The mean concentration of serum IL-2 and IL-6 were not different between the groups (P = 0.261, P = 0.141 respectively). The median concentrations of serum IL-10 in patients with mild and severe pre-eclampsia were similar (P < 0.282) and was significantly lower than those of controls (P < 0.001) and patients with eclampsia (P < 0.001). In patients with eclampsia, the median concentration of IL-10 was significantly higher than that of all other groups (P < 0.001 for each comparison).ConclusionPre-eclampsia is associated with a deficiency serum IL-10. High serum IL-10 is correlated with the presence of eclampsia.Pre-eclampsia is associated with a deficiency serum IL-10. High serum IL-10 is correlated with the presence of eclampsia.

Research paper thumbnail of The transglutaminase 2 gene (TGM2), a potential molecular marker for chemotherapeutic drug sensitivity, is epigenetically silenced in breast cancer

Carcinogenesis, 2007

Tissue transglutaminase (TG2) is a ubiquitously expressed enzyme capable of catalyzing protein cr... more Tissue transglutaminase (TG2) is a ubiquitously expressed enzyme capable of catalyzing protein cross-links. TG2-dependent cross-links are important in extracellular matrix integrity and it has been proposed that this TG2 activity establishes a barrier to tumor spread. Furthermore, TG2 controls sensitivity to the chemotherapeutic drug doxorubicin. Both doxorubicin sensitivity and TG2 expression are highly variable in cultured human breast cancer cell lines and inspection of the human gene (termed TGM2) determined that a canonical CpG island exists within its 5# flank. These features, when combined with its potential tumor suppressor activity, make TG2 an attractive candidate for epigenetic silencing. Consistent with this, we observed that culturing breast tumor cells with the DNA demethylating agent 5-aza-2#deoxycytidine (5-azadC) resulted in a robust increase in TG2 expression. Analysis of DNA harvested from cultured lines and primary breast tumor samples indicated that TGM2 often displays aberrant hypermethylation and that there is a statistically significant correlation between gene methylation and reduced expression. Finally, we observed that doxorubicin-resistant MCF-7/ ADR cells do not show TGM2 silencing but that doxorubicinsensitive MCF-7 cells do and that culturing MCF-7 cells on 5-azadC and subsequently restoring TG2 expression reduced sensitivity to doxorubicin. This work indicates that the TGM2 gene is a target for epigenetic silencing in breast cancer and suggests that this aberrant molecular event is a potential marker for chemotherapeutic drug sensitivity.

Research paper thumbnail of Comparative epigenomics of human and mouse mammary tumors

Genes Chromosomes & Cancer, 2009

Gene silencing by aberrant epigenetic chromatin alteration is a well-recognized event contributin... more Gene silencing by aberrant epigenetic chromatin alteration is a well-recognized event contributing to tumorigenesis. Although genetically engineered tumor-prone mouse models have proven a powerful tool in understanding many aspects of carcinogenesis, to date few studies have focused on epigenetic alterations in mouse tumors. To uncover epigenetically silenced tumor suppressor genes (TSGs) in mouse mammary tumor cells, we conducted initial genome-wide screening by combining the treatment of cultured cells with the DNA demethylating drug 5-aza-2′-deoxycytidine (5-azadC) and the histone deacetylase inhibitor trichostatin A (TSA) with expression microarray. By conducting this initial screen on EMT6 cells and applying protein function and genomic structure criteria to genes identified as upregulated in response to 5-azadC/TSA, we were able to identify two characterized breast cancer TSGs (Timp3 and Rprm) and four putative TSGs (Atp1B2, Dusp2, FoxJ1 and Smpd3) silenced in this line. By testing a panel of 10 mouse mammary tumor lines, we determined that each of these genes is commonly hypermethylated, albeit with varying frequency. Furthermore, by examining a panel of human breast tumor lines and primary tumors we observed that the human orthologs of ATP1B2, FOXJ1 and SMPD3 are aberrantly hypermethylated in the human disease whereas DUSP2 was not hypermethylated in primary breast tumors. Finally, we examined hypermethylation of several genes targeted for epigenetic silencing in human breast tumors in our panel of 10 mouse mammary tumor lines. We observed that the orthologs of Cdh1, RarB, Gstp1, RassF1 genes were hypermethylated, whereas neither Dapk1 nor Wif1 were aberrantly methylated in this panel of mouse tumor lines. From this study, we conclude that there is significant, but not absolute, overlap in the epigenome of human and mouse mammary tumors. © 2008 Wiley-Liss, Inc.

Research paper thumbnail of The transglutaminase 2 gene (TGM2), a potential molecular marker for chemotherapeutic drug sensitivity, is epigenetically silenced in breast cancer

Tissue transglutaminase (TG2) is a ubiquitously expressed enzyme capable of catalyzing protein cr... more Tissue transglutaminase (TG2) is a ubiquitously expressed enzyme capable of catalyzing protein cross-links. TG2-dependent cross-links are important in extracellular matrix integrity and it has been proposed that this TG2 activity establishes a barrier to tumor spread. Furthermore, TG2 controls sensitivity to the chemotherapeutic drug doxorubicin. Both doxorubicin sensitivity and TG2 expression are highly variable in cultured human breast cancer cell lines and inspection of the human gene (termed TGM2) determined that a canonical CpG island exists within its 5# flank. These features, when combined with its potential tumor suppressor activity, make TG2 an attractive candidate for epigenetic silencing. Consistent with this, we observed that culturing breast tumor cells with the DNA demethylating agent 5-aza-2#deoxycytidine (5-azadC) resulted in a robust increase in TG2 expression. Analysis of DNA harvested from cultured lines and primary breast tumor samples indicated that TGM2 often displays aberrant hypermethylation and that there is a statistically significant correlation between gene methylation and reduced expression. Finally, we observed that doxorubicin-resistant MCF-7/ ADR cells do not show TGM2 silencing but that doxorubicinsensitive MCF-7 cells do and that culturing MCF-7 cells on 5-azadC and subsequently restoring TG2 expression reduced sensitivity to doxorubicin. This work indicates that the TGM2 gene is a target for epigenetic silencing in breast cancer and suggests that this aberrant molecular event is a potential marker for chemotherapeutic drug sensitivity.

Research paper thumbnail of The transglutaminase 2 gene (TGM2), a potential molecular marker for chemotherapeutic drug sensitivity, is epigenetically silenced in breast cancer

Carcinogenesis, 2007

Tissue transglutaminase (TG2) is a ubiquitously expressed enzyme capable of catalyzing protein cr... more Tissue transglutaminase (TG2) is a ubiquitously expressed enzyme capable of catalyzing protein cross-links. TG2-dependent cross-links are important in extracellular matrix integrity and it has been proposed that this TG2 activity establishes a barrier to tumor spread. Furthermore, TG2 controls sensitivity to the chemotherapeutic drug doxorubicin. Both doxorubicin sensitivity and TG2 expression are highly variable in cultured human breast cancer cell lines and inspection of the human gene (termed TGM2) determined that a canonical CpG island exists within its 5# flank. These features, when combined with its potential tumor suppressor activity, make TG2 an attractive candidate for epigenetic silencing. Consistent with this, we observed that culturing breast tumor cells with the DNA demethylating agent 5-aza-2#deoxycytidine (5-azadC) resulted in a robust increase in TG2 expression. Analysis of DNA harvested from cultured lines and primary breast tumor samples indicated that TGM2 often displays aberrant hypermethylation and that there is a statistically significant correlation between gene methylation and reduced expression. Finally, we observed that doxorubicin-resistant MCF-7/ ADR cells do not show TGM2 silencing but that doxorubicinsensitive MCF-7 cells do and that culturing MCF-7 cells on 5-azadC and subsequently restoring TG2 expression reduced sensitivity to doxorubicin. This work indicates that the TGM2 gene is a target for epigenetic silencing in breast cancer and suggests that this aberrant molecular event is a potential marker for chemotherapeutic drug sensitivity.

Research paper thumbnail of Comparative epigenomics of human and mouse mammary tumors

Genes Chromosomes & Cancer, 2009

Gene silencing by aberrant epigenetic chromatin alteration is a well-recognized event contributin... more Gene silencing by aberrant epigenetic chromatin alteration is a well-recognized event contributing to tumorigenesis. Although genetically engineered tumor-prone mouse models have proven a powerful tool in understanding many aspects of carcinogenesis, to date few studies have focused on epigenetic alterations in mouse tumors. To uncover epigenetically silenced tumor suppressor genes (TSGs) in mouse mammary tumor cells, we conducted initial genome-wide screening by combining the treatment of cultured cells with the DNA demethylating drug 5-aza-2′-deoxycytidine (5-azadC) and the histone deacetylase inhibitor trichostatin A (TSA) with expression microarray. By conducting this initial screen on EMT6 cells and applying protein function and genomic structure criteria to genes identified as upregulated in response to 5-azadC/TSA, we were able to identify two characterized breast cancer TSGs (Timp3 and Rprm) and four putative TSGs (Atp1B2, Dusp2, FoxJ1 and Smpd3) silenced in this line. By testing a panel of 10 mouse mammary tumor lines, we determined that each of these genes is commonly hypermethylated, albeit with varying frequency. Furthermore, by examining a panel of human breast tumor lines and primary tumors we observed that the human orthologs of ATP1B2, FOXJ1 and SMPD3 are aberrantly hypermethylated in the human disease whereas DUSP2 was not hypermethylated in primary breast tumors. Finally, we examined hypermethylation of several genes targeted for epigenetic silencing in human breast tumors in our panel of 10 mouse mammary tumor lines. We observed that the orthologs of Cdh1, RarB, Gstp1, RassF1 genes were hypermethylated, whereas neither Dapk1 nor Wif1 were aberrantly methylated in this panel of mouse tumor lines. From this study, we conclude that there is significant, but not absolute, overlap in the epigenome of human and mouse mammary tumors. © 2008 Wiley-Liss, Inc.

Research paper thumbnail of The transglutaminase 2 gene (TGM2), a potential molecular marker for chemotherapeutic drug sensitivity, is epigenetically silenced in breast cancer

Tissue transglutaminase (TG2) is a ubiquitously expressed enzyme capable of catalyzing protein cr... more Tissue transglutaminase (TG2) is a ubiquitously expressed enzyme capable of catalyzing protein cross-links. TG2-dependent cross-links are important in extracellular matrix integrity and it has been proposed that this TG2 activity establishes a barrier to tumor spread. Furthermore, TG2 controls sensitivity to the chemotherapeutic drug doxorubicin. Both doxorubicin sensitivity and TG2 expression are highly variable in cultured human breast cancer cell lines and inspection of the human gene (termed TGM2) determined that a canonical CpG island exists within its 5# flank. These features, when combined with its potential tumor suppressor activity, make TG2 an attractive candidate for epigenetic silencing. Consistent with this, we observed that culturing breast tumor cells with the DNA demethylating agent 5-aza-2#deoxycytidine (5-azadC) resulted in a robust increase in TG2 expression. Analysis of DNA harvested from cultured lines and primary breast tumor samples indicated that TGM2 often displays aberrant hypermethylation and that there is a statistically significant correlation between gene methylation and reduced expression. Finally, we observed that doxorubicin-resistant MCF-7/ ADR cells do not show TGM2 silencing but that doxorubicinsensitive MCF-7 cells do and that culturing MCF-7 cells on 5-azadC and subsequently restoring TG2 expression reduced sensitivity to doxorubicin. This work indicates that the TGM2 gene is a target for epigenetic silencing in breast cancer and suggests that this aberrant molecular event is a potential marker for chemotherapeutic drug sensitivity.

Research paper thumbnail of Effects of indomethacin, celecoxib and meloxicam on glutathione, malondialdehyde and myeloperoxidase in rat gastric tissue

Pain Clinic, 2005

Abstract: In the present study, we examined the effects of indomethacin, celecoxib and meloxicam ... more Abstract: In the present study, we examined the effects of indomethacin, celecoxib and meloxicam on the stomach and on levels of glutathione (GSH), malondialdehyde (MDA) and activity of myeloperoxidase (MPO) in gastric tissues of rats. The ulcer area was 31.1±10.7 ...

Research paper thumbnail of ANTI-INFLAMMATORY EFFECTS OF SELECTIVE COX2 INHIBITORS

In this study, effects of rofecoxib, celecoxib, nimesulide on the acute phase of inflammation wer... more In this study, effects of rofecoxib, celecoxib, nimesulide on the acute phase of inflammation were studied in the carrageenan-induced paw edema model and their influence on the chronic phase of inflammation was evaluated in the cotton pellet granuloma tests. Additionally, effects of these drugs on capillary vascular permeability were examined in the hyaluronidase test and were compared with that of indomethacin (nonselective COX inhibitor).

Research paper thumbnail of Anti-inflammatory and side effects of cyclooxygenase inhibitors

Nonsteroidal anti-inflammatory drugs (NSAIDs) are the most commonly used drugs in inflammatory di... more Nonsteroidal anti-inflammatory drugs (NSAIDs) are the most commonly used drugs in inflammatory diseases, since they are effective in management of pain, fever, redness, edema arising as a consequence of inflammatory mediator release. Studies have shown that both therapeutic and side effects of NSAIDs are dependent on cyclooxygenase (COX) inhibition. COX isoforms have been named constitutive (COX-1) and inducible (COX-2). COX-1 catalyzes formation of cytoprotective prostaglandins in thrombocytes, vascular endothelium, stomach mucosa, kidneys, pancreas, Langerhans islets, seminal vesicles, and brain. Induction of COX-2 by various growth factors, proinflammatory agents, endotoxins, mitogens, and tumor agents indicates that this isoform may have a role in induction of pathological processes, such as inflammation. It is well known that therapy with COX inhibitors is associated with a number of side effects including gastrointestinal erosions, and renal and hepatic insufficiency. Such critical adverse reactions are mostly dependent on COX-1 inhibition. As a result of research focused on reduction of the adverse effects of NSAIDs, selective COX-2 inhibitors, such as celecoxib and rofecoxib have been developed. However, many data demonstrate that mechanisms of action of these drugs are multidirectional and complex. These drugs or their derivatives, which belong to the same group, have distinct pharmacological effects, side effects and potencies which implies that there may be more than two, five or even tens of COX isoforms.

Research paper thumbnail of EFFECTS OF ENDURANCE TRAINING ON ANTIOXIDANT DEFENSE MECHANISMS AND LIPID PEROXIDATION IN TESTIS OF RATS

Systems Biology in Reproductive Medicine, 2006

Research paper thumbnail of Maternal Serum Interleukin10, Interleukin2 and Interleukin6 in Pre-Eclampsia and Eclampsia

American Journal of Reproductive Immunology, 2007

ProblemThe aim of the study was to investigate and compare the concentrations of interleukin (IL)... more ProblemThe aim of the study was to investigate and compare the concentrations of interleukin (IL)-2, IL-6, and IL-10 in serum of women with mild pre-eclampsia, severe pre-eclampsia, eclampsia, and normotensive pregnancy.The aim of the study was to investigate and compare the concentrations of interleukin (IL)-2, IL-6, and IL-10 in serum of women with mild pre-eclampsia, severe pre-eclampsia, eclampsia, and normotensive pregnancy.Method of studyA total of 69 consecutive cases, 38 mild pre-eclampsia, 20 severe pre-eclampsia, 11 eclampsia, and 20 normotensive controls were included in this study. Serum IL-2, IL-6, and IL-10 levels were determined using enzyme-linked immunosorbent assay method.A total of 69 consecutive cases, 38 mild pre-eclampsia, 20 severe pre-eclampsia, 11 eclampsia, and 20 normotensive controls were included in this study. Serum IL-2, IL-6, and IL-10 levels were determined using enzyme-linked immunosorbent assay method.ResultsGestational age (P = 0.210) and body mass index (P = 0.214) between the groups were similar. The mean concentration of serum IL-2 and IL-6 were not different between the groups (P = 0.261, P = 0.141 respectively). The median concentrations of serum IL-10 in patients with mild and severe pre-eclampsia were similar (P < 0.282) and was significantly lower than those of controls (P < 0.001) and patients with eclampsia (P < 0.001). In patients with eclampsia, the median concentration of IL-10 was significantly higher than that of all other groups (P < 0.001 for each comparison).Gestational age (P = 0.210) and body mass index (P = 0.214) between the groups were similar. The mean concentration of serum IL-2 and IL-6 were not different between the groups (P = 0.261, P = 0.141 respectively). The median concentrations of serum IL-10 in patients with mild and severe pre-eclampsia were similar (P < 0.282) and was significantly lower than those of controls (P < 0.001) and patients with eclampsia (P < 0.001). In patients with eclampsia, the median concentration of IL-10 was significantly higher than that of all other groups (P < 0.001 for each comparison).ConclusionPre-eclampsia is associated with a deficiency serum IL-10. High serum IL-10 is correlated with the presence of eclampsia.Pre-eclampsia is associated with a deficiency serum IL-10. High serum IL-10 is correlated with the presence of eclampsia.

Research paper thumbnail of The transglutaminase 2 gene (TGM2), a potential molecular marker for chemotherapeutic drug sensitivity, is epigenetically silenced in breast cancer

Carcinogenesis, 2007

Tissue transglutaminase (TG2) is a ubiquitously expressed enzyme capable of catalyzing protein cr... more Tissue transglutaminase (TG2) is a ubiquitously expressed enzyme capable of catalyzing protein cross-links. TG2-dependent cross-links are important in extracellular matrix integrity and it has been proposed that this TG2 activity establishes a barrier to tumor spread. Furthermore, TG2 controls sensitivity to the chemotherapeutic drug doxorubicin. Both doxorubicin sensitivity and TG2 expression are highly variable in cultured human breast cancer cell lines and inspection of the human gene (termed TGM2) determined that a canonical CpG island exists within its 5# flank. These features, when combined with its potential tumor suppressor activity, make TG2 an attractive candidate for epigenetic silencing. Consistent with this, we observed that culturing breast tumor cells with the DNA demethylating agent 5-aza-2#deoxycytidine (5-azadC) resulted in a robust increase in TG2 expression. Analysis of DNA harvested from cultured lines and primary breast tumor samples indicated that TGM2 often displays aberrant hypermethylation and that there is a statistically significant correlation between gene methylation and reduced expression. Finally, we observed that doxorubicin-resistant MCF-7/ ADR cells do not show TGM2 silencing but that doxorubicinsensitive MCF-7 cells do and that culturing MCF-7 cells on 5-azadC and subsequently restoring TG2 expression reduced sensitivity to doxorubicin. This work indicates that the TGM2 gene is a target for epigenetic silencing in breast cancer and suggests that this aberrant molecular event is a potential marker for chemotherapeutic drug sensitivity.

Research paper thumbnail of Comparative epigenomics of human and mouse mammary tumors

Genes Chromosomes & Cancer, 2009

Gene silencing by aberrant epigenetic chromatin alteration is a well-recognized event contributin... more Gene silencing by aberrant epigenetic chromatin alteration is a well-recognized event contributing to tumorigenesis. Although genetically engineered tumor-prone mouse models have proven a powerful tool in understanding many aspects of carcinogenesis, to date few studies have focused on epigenetic alterations in mouse tumors. To uncover epigenetically silenced tumor suppressor genes (TSGs) in mouse mammary tumor cells, we conducted initial genome-wide screening by combining the treatment of cultured cells with the DNA demethylating drug 5-aza-2′-deoxycytidine (5-azadC) and the histone deacetylase inhibitor trichostatin A (TSA) with expression microarray. By conducting this initial screen on EMT6 cells and applying protein function and genomic structure criteria to genes identified as upregulated in response to 5-azadC/TSA, we were able to identify two characterized breast cancer TSGs (Timp3 and Rprm) and four putative TSGs (Atp1B2, Dusp2, FoxJ1 and Smpd3) silenced in this line. By testing a panel of 10 mouse mammary tumor lines, we determined that each of these genes is commonly hypermethylated, albeit with varying frequency. Furthermore, by examining a panel of human breast tumor lines and primary tumors we observed that the human orthologs of ATP1B2, FOXJ1 and SMPD3 are aberrantly hypermethylated in the human disease whereas DUSP2 was not hypermethylated in primary breast tumors. Finally, we examined hypermethylation of several genes targeted for epigenetic silencing in human breast tumors in our panel of 10 mouse mammary tumor lines. We observed that the orthologs of Cdh1, RarB, Gstp1, RassF1 genes were hypermethylated, whereas neither Dapk1 nor Wif1 were aberrantly methylated in this panel of mouse tumor lines. From this study, we conclude that there is significant, but not absolute, overlap in the epigenome of human and mouse mammary tumors. © 2008 Wiley-Liss, Inc.

Research paper thumbnail of The transglutaminase 2 gene (TGM2), a potential molecular marker for chemotherapeutic drug sensitivity, is epigenetically silenced in breast cancer

Tissue transglutaminase (TG2) is a ubiquitously expressed enzyme capable of catalyzing protein cr... more Tissue transglutaminase (TG2) is a ubiquitously expressed enzyme capable of catalyzing protein cross-links. TG2-dependent cross-links are important in extracellular matrix integrity and it has been proposed that this TG2 activity establishes a barrier to tumor spread. Furthermore, TG2 controls sensitivity to the chemotherapeutic drug doxorubicin. Both doxorubicin sensitivity and TG2 expression are highly variable in cultured human breast cancer cell lines and inspection of the human gene (termed TGM2) determined that a canonical CpG island exists within its 5# flank. These features, when combined with its potential tumor suppressor activity, make TG2 an attractive candidate for epigenetic silencing. Consistent with this, we observed that culturing breast tumor cells with the DNA demethylating agent 5-aza-2#deoxycytidine (5-azadC) resulted in a robust increase in TG2 expression. Analysis of DNA harvested from cultured lines and primary breast tumor samples indicated that TGM2 often displays aberrant hypermethylation and that there is a statistically significant correlation between gene methylation and reduced expression. Finally, we observed that doxorubicin-resistant MCF-7/ ADR cells do not show TGM2 silencing but that doxorubicinsensitive MCF-7 cells do and that culturing MCF-7 cells on 5-azadC and subsequently restoring TG2 expression reduced sensitivity to doxorubicin. This work indicates that the TGM2 gene is a target for epigenetic silencing in breast cancer and suggests that this aberrant molecular event is a potential marker for chemotherapeutic drug sensitivity.

Research paper thumbnail of The transglutaminase 2 gene (TGM2), a potential molecular marker for chemotherapeutic drug sensitivity, is epigenetically silenced in breast cancer

Carcinogenesis, 2007

Tissue transglutaminase (TG2) is a ubiquitously expressed enzyme capable of catalyzing protein cr... more Tissue transglutaminase (TG2) is a ubiquitously expressed enzyme capable of catalyzing protein cross-links. TG2-dependent cross-links are important in extracellular matrix integrity and it has been proposed that this TG2 activity establishes a barrier to tumor spread. Furthermore, TG2 controls sensitivity to the chemotherapeutic drug doxorubicin. Both doxorubicin sensitivity and TG2 expression are highly variable in cultured human breast cancer cell lines and inspection of the human gene (termed TGM2) determined that a canonical CpG island exists within its 5# flank. These features, when combined with its potential tumor suppressor activity, make TG2 an attractive candidate for epigenetic silencing. Consistent with this, we observed that culturing breast tumor cells with the DNA demethylating agent 5-aza-2#deoxycytidine (5-azadC) resulted in a robust increase in TG2 expression. Analysis of DNA harvested from cultured lines and primary breast tumor samples indicated that TGM2 often displays aberrant hypermethylation and that there is a statistically significant correlation between gene methylation and reduced expression. Finally, we observed that doxorubicin-resistant MCF-7/ ADR cells do not show TGM2 silencing but that doxorubicinsensitive MCF-7 cells do and that culturing MCF-7 cells on 5-azadC and subsequently restoring TG2 expression reduced sensitivity to doxorubicin. This work indicates that the TGM2 gene is a target for epigenetic silencing in breast cancer and suggests that this aberrant molecular event is a potential marker for chemotherapeutic drug sensitivity.

Research paper thumbnail of Comparative epigenomics of human and mouse mammary tumors

Genes Chromosomes & Cancer, 2009

Gene silencing by aberrant epigenetic chromatin alteration is a well-recognized event contributin... more Gene silencing by aberrant epigenetic chromatin alteration is a well-recognized event contributing to tumorigenesis. Although genetically engineered tumor-prone mouse models have proven a powerful tool in understanding many aspects of carcinogenesis, to date few studies have focused on epigenetic alterations in mouse tumors. To uncover epigenetically silenced tumor suppressor genes (TSGs) in mouse mammary tumor cells, we conducted initial genome-wide screening by combining the treatment of cultured cells with the DNA demethylating drug 5-aza-2′-deoxycytidine (5-azadC) and the histone deacetylase inhibitor trichostatin A (TSA) with expression microarray. By conducting this initial screen on EMT6 cells and applying protein function and genomic structure criteria to genes identified as upregulated in response to 5-azadC/TSA, we were able to identify two characterized breast cancer TSGs (Timp3 and Rprm) and four putative TSGs (Atp1B2, Dusp2, FoxJ1 and Smpd3) silenced in this line. By testing a panel of 10 mouse mammary tumor lines, we determined that each of these genes is commonly hypermethylated, albeit with varying frequency. Furthermore, by examining a panel of human breast tumor lines and primary tumors we observed that the human orthologs of ATP1B2, FOXJ1 and SMPD3 are aberrantly hypermethylated in the human disease whereas DUSP2 was not hypermethylated in primary breast tumors. Finally, we examined hypermethylation of several genes targeted for epigenetic silencing in human breast tumors in our panel of 10 mouse mammary tumor lines. We observed that the orthologs of Cdh1, RarB, Gstp1, RassF1 genes were hypermethylated, whereas neither Dapk1 nor Wif1 were aberrantly methylated in this panel of mouse tumor lines. From this study, we conclude that there is significant, but not absolute, overlap in the epigenome of human and mouse mammary tumors. © 2008 Wiley-Liss, Inc.

Research paper thumbnail of The transglutaminase 2 gene (TGM2), a potential molecular marker for chemotherapeutic drug sensitivity, is epigenetically silenced in breast cancer

Tissue transglutaminase (TG2) is a ubiquitously expressed enzyme capable of catalyzing protein cr... more Tissue transglutaminase (TG2) is a ubiquitously expressed enzyme capable of catalyzing protein cross-links. TG2-dependent cross-links are important in extracellular matrix integrity and it has been proposed that this TG2 activity establishes a barrier to tumor spread. Furthermore, TG2 controls sensitivity to the chemotherapeutic drug doxorubicin. Both doxorubicin sensitivity and TG2 expression are highly variable in cultured human breast cancer cell lines and inspection of the human gene (termed TGM2) determined that a canonical CpG island exists within its 5# flank. These features, when combined with its potential tumor suppressor activity, make TG2 an attractive candidate for epigenetic silencing. Consistent with this, we observed that culturing breast tumor cells with the DNA demethylating agent 5-aza-2#deoxycytidine (5-azadC) resulted in a robust increase in TG2 expression. Analysis of DNA harvested from cultured lines and primary breast tumor samples indicated that TGM2 often displays aberrant hypermethylation and that there is a statistically significant correlation between gene methylation and reduced expression. Finally, we observed that doxorubicin-resistant MCF-7/ ADR cells do not show TGM2 silencing but that doxorubicinsensitive MCF-7 cells do and that culturing MCF-7 cells on 5-azadC and subsequently restoring TG2 expression reduced sensitivity to doxorubicin. This work indicates that the TGM2 gene is a target for epigenetic silencing in breast cancer and suggests that this aberrant molecular event is a potential marker for chemotherapeutic drug sensitivity.