Etoposide-induced apoptosis results in chromosome breaks within the &amp;lt;i&amp;gt;AF&amp;lt;/i&amp;gt;9 gene: Its implication in chromosome rearrangement in leukaemia

Nicholas, Cynthia Patricia; Sim, Sai‐Peng

doi:10.4236/abb.2012.326089

Cited by 5 publications

(7 citation statements)

References 44 publications

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“…This chromosome break falls within the AF9 region (at coordinates 245,252–245,612) that was previously reported to be involved in the formation of the MLL - AF9 fusion gene in an ALL patient. This breakpoint is three nucleotides different from that reported in cultured normal blood cells treated with VP16 (at coordinate 245,593) [101], five nucleotides different from a breakpoint detected in H 2 O 2 -treated NP69 cells (at coordinate 245,591) and six nucleotides different from that identified in H 2 O 2 -treated HK1 cells (at coordinate 245,590) [97]. 245,649This chromosome break falls within a repeat ERE2_EH (at coordinates 245,627–245,728).245,725This chromosome break falls within a repeat ERE2_EH (at coordinates 245,627–245,728).245,9790.5 mM BA, pH 5.8245,621This breakpoint is nine nucleotides different from that identified in an ALL patient (at coordinate 245,612) [GenBank:AM050804].245,699This breakpoint is four nucleotides different from that reported in H 2 O 2 -treated NP69 cells (at coordinate 245,703) [97].…”

Section: Resultscontrasting

confidence: 64%

“…This chromosome break falls within the AF9 region (at coordinates 245,252–245,612) previously reported to be involved in the formation of the MLL - AF9 fusion gene in an ALL patient [GenBank:AM050804]. This breakpoint is three nucleotides different from that reported in cultured normal blood cells treated with VP16 (at coordinate 245,593) [101], five nucleotides different from that detected in H 2 O 2 -treated NP69 cells (at coordinate 245,591) and six nucleotides different from that identified in H 2 O 2 -treated HK1 cells (at coordinate 245,590) [97]. 245,664This breakpoint is five nucleotides different from that (at coordinate 245,659) identified in NP69 cells treated with H 2 O 2 [97].…”

Section: Resultsmentioning

confidence: 82%

“…This chromosome break falls within a repeat ERE2_EH (at coordinates 245,627–245,728).245,711This chromosome break falls within a repeat ERE2_EH (at coordinates 245,627–245,728).245,769245,803This breakpoint is identical with that identified in TWO4 cells treated with BA at pH 5.8.245,913245,935245,9440.5 mM BA, pH 5.8245,509This chromosome break falls within the AF9 region (at coordinates 245,252–245,612) that was previously reported to translocate with the MLL gene leading to the formation of the MLL - AF9 fusion gene in an ALL patient [GenBank:AM050804].245,577This chromosome break falls within the AF9 region (at coordinates 245,252–245,612) that was previously reported to translocate with the MLL gene leading to the formation of the MLL - AF9 fusion gene in an ALL patient [GenBank:AM050804].245,594This chromosome break falls within the AF9 region (at coordinates 245,252–245,612) that was previously reported to translocate with the MLL gene leading to the formation of the MLL - AF9 fusion gene in an ALL patient [GenBank:AM050804]. This breakpoint is one nucleotide different from that reported in cultured normal blood cells treated with VP16 (at coordinate 245,593) [101], three nucleotides different from that detected in H 2 O 2 -treated NP69 cells (at coordinate 245,591), and four nucleotides different from that identified in H 2 O 2 -treated HK1 cells (245590) [97]. 245,612This breakpoint is identical with the breakpoint previously identified in an ALL patient [GenBank:AM050804].245,637This chromosome break falls within a repeat ERE2_EH (at coordinates 245,627–245,728).245,729245,753245,803This breakpoint is identical with a breakpoint identified in TWO4 cells treated with BA at pH 7.4, and seven nucleotides different from that (at coordinate 245,796) reported in NP69 cells treated with H 2 O 2 [97].…”

Section: Resultsmentioning

confidence: 95%

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Matrix association region/scaffold attachment region: the crucial player in defining the positions of chromosome breaks mediated by bile acid-induced apoptosis in nasopharyngeal epithelial cells

Tan¹,

Sim²

2019

BMC Med Genomics

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BackgroundIt has been found that chronic rhinosinusitis (CRS) increases the risk of developing nasopharyngeal carcinoma (NPC). CRS can be caused by gastro-oesophageal reflux (GOR) that may reach nasopharynx. The major component of refluxate, bile acid (BA) has been found to be carcinogenic and genotoxic. BA-induced apoptosis has been associated with various cancers. We have previously demonstrated that BA induced apoptosis and gene cleavages in nasopharyngeal epithelial cells. Chromosomal cleavage occurs at the early stage of both apoptosis and chromosome rearrangement. It was suggested that chromosome breaks tend to cluster in the region containing matrix association region/scaffold attachment region (MAR/SAR). This study hypothesised that BA may cause chromosome breaks at MAR/SAR leading to chromosome aberrations in NPC. This study targeted the AF9 gene located at 9p22 because 9p22 is a deletion hotspot in NPC.MethodsPotential MAR/SAR sites were predicted in the AF9 gene by using MAR/SAR prediction tools. Normal nasopharyngeal epithelial cells (NP69) and NPC cells (TWO4) were treated with BA at neutral and acidic pH. Inverse-PCR (IPCR) was used to identify chromosome breaks in SAR region (contains MAR/SAR) and non-SAR region (does not contain MAR/SAR). To map the chromosomal breakpoints within the AF9 SAR and non-SAR regions, DNA sequencing was performed.ResultsIn the AF9 SAR region, the gene cleavage frequencies of BA-treated NP69 and TWO4 cells were significantly higher than those of untreated control. As for the AF9 non-SAR region, no significant difference in cleavage frequency was detected between untreated and BA-treated cells. A few breakpoints detected in the SAR region were mapped within the AF9 region that was previously reported to translocate with the mixed lineage leukaemia (MLL) gene in an acute lymphoblastic leukaemia (ALL) patient.ConclusionsOur findings suggest that MAR/SAR may be involved in defining the positions of chromosomal breakages induced by BA. Our report here, for the first time, unravelled the relation of these BA-induced chromosomal breakages to the AF9 chromatin structure.Electronic supplementary materialThe online version of this article (10.1186/s12920-018-0465-4) contains supplementary material, which is available to authorized users.

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Section: Resultscontrasting

confidence: 64%

Section: Resultsmentioning

confidence: 82%

Section: Resultsmentioning

confidence: 95%

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Matrix association region/scaffold attachment region: the crucial player in defining the positions of chromosome breaks mediated by bile acid-induced apoptosis in nasopharyngeal epithelial cells

Tan¹,

Sim²

2019

BMC Med Genomics

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“…Various mechanisms of chromosome rearrangements have been proposed in other malignancies. These include mechanisms involving Alu repeats [ 11 ], V (D) J recombination [ 12 ], DNA topoisomerase II [ 13 ] and apoptosis [ 14 , 15 ]. More recently, caspase-activated DNase (CAD) is also implicated in chromosome rearrangement in NPC [ 16 ].…”

Section: Introductionmentioning

confidence: 99%

“…CAD seems to be playing multiple roles. On one hand it is the apoptotic nuclease, one the other hand, it was also found to play a role in chromosome rearrangement commonly found in leukaemia [ 14 , 15 , 28 ]. In addition, CAD was also shown to promote cell differentiation by inducing DNA strand breaks [ 29 ].…”

Section: Introductionmentioning

confidence: 99%

Inhibitor of caspase-activated DNase expression enhances caspase-activated DNase expression and inhibits oxidative stress-induced chromosome breaks at the mixed lineage leukaemia gene in nasopharyngeal carcinoma cells

Boon

Sim

2015

Cancer Cell Int

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BackgroundNasopharyngeal carcinoma (NPC) is commonly found in Asia, especially among the Chinese ethnic group. Chromosome rearrangements are common among NPC patients. Although the mechanism underlying the chromosome rearrangements in NPC is unclear, various mechanisms including activation of caspase-activated DNase (CAD) were proposed to contribute to chromosome rearrangements in leukaemia. Activation of CAD can be initiated by multiple agents, including oxidative stress, which is well implicated in carcinogenesis. CAD is the main enzyme that causes DNA fragmentation during apoptosis, and CAD is also implicated in promoting cell differentiation. In view of the role of oxidative stress in carcinogenesis and CAD activation, and since CAD was suggested to contribute to chromosome rearrangement in leukaemia, we hypothesise that oxidative stress-induced CAD activation could be one of the mechanisms that leads to chromosome rearrangements in NPC.MethodsSUNEI cells were treated with various concentrations of H2O2 for different period of time to ensure that cells undergo H2O2-induced MLL gene cleavage. Transfections with hCAD, mCAD, mutant hCAD, or cotransfection with hCAD and mICAD, and cotransfection with mutant hCAD and mICAD were performed. Gene expression was confirmed by Western blotting and MLL gene cleavage was assessed by inverse polymerase chain reaction (IPCR).ResultsTreatment with H2O2 clearly induces cleavages within the MLL gene which locates at 11q23, a common deletion site in NPC. In order to investigate the role of CAD, CAD was overexpressed in SUNE1 cells, but that did not result in significant changes in H2O2-induced MLL gene cleavage. This could be because CAD requires ICAD for proper folding. Indeed, by overexpressing ICAD alone or co-expressing ICAD with CAD, Western blotting showed that CAD was expressed. In addition, ICAD overexpression also suppressed H2O2-induced MLL gene cleavage, suggesting a possible role of CAD in initiating chromosome cleavage during oxidative stress.ConclusionsOxidative stress mediated by H2O2 induces cleavage of the MLL gene, most likely via the caspase-activated DNase, CAD, and CAD expression requires ICAD. Since the MLL gene is located at 11q23, a common deletion site in NPC, thus stress-induced CAD activation may represent one of the mechanisms leading to chromosome rearrangement in NPC.

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Matrix association region/scaffold attachment region (MAR/SAR) sequence: its vital role in mediating chromosome breakages in nasopharyngeal epithelial cells via oxidative stress-induced apoptosis

2018

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BackgroundOxidative stress is known to be involved in most of the aetiological factors of nasopharyngeal carcinoma (NPC). Cells that are under oxidative stress may undergo apoptosis. We have previously demonstrated that oxidative stress-induced apoptosis could be a potential mechanism mediating chromosome breakages in nasopharyngeal epithelial cells. Additionally, caspase-activated DNase (CAD) may be the vital player in mediating the chromosomal breakages during oxidative stress-induced apoptosis. Chromosomal breakage occurs during apoptosis and chromosome rearrangement. Chromosomal breakages tend to cluster in certain regions, such as matrix association region/scaffold attachment region (MAR/SAR). We hypothesised that oxidative stress-induced apoptosis may result in chromosome breaks preferentially at the MAR/SAR sites. The AF9 gene at 9p22 was targeted in this study because 9p22 is a deletion site commonly found in NPC.ResultsBy using MAR/SAR recognition signature (MRS), potential MAR/SAR sites were predicted in the AF9 gene. The predicted MAR/SAR sites precisely match to the experimentally determined MAR/SARs. Hydrogen peroxide (H2O2) was used to induce apoptosis in normal nasopharyngeal epithelial cells (NP69) and NPC cells (HK1). Nested inverse polymerase chain reaction was employed to identify the AF9 gene cleavages. In the SAR region, the gene cleavage frequency of H2O2-treated cells was significantly higher than that of the non-treated cells. A few chromosomal breakages were detected within the AF9 region which was previously found to be involved in the mixed lineage leukaemia (MLL)-AF9 translocation in an acute lymphoblastic leukaemia patient. As for the non-SAR region, no significant difference in the gene cleavage frequency was found between the untreated control and H2O2-treated cells. Furthermore, H2O2-induced cleavages within the SAR region were reduced by caspase-3 inhibitor, which indirectly inhibits CAD.ConclusionsThese results reaffirm our previous findings that oxidative stress-induced apoptosis could be one of the potential mechanisms underlying chromosome breakages in nasopharyngeal epithelial cells. MAR/SAR may play a vital role in defining the location of chromosomal breakages mediated by oxidative stress-induced apoptosis, where CAD is the major nuclease.Electronic supplementary materialThe online version of this article (10.1186/s12867-018-0116-5) contains supplementary material, which is available to authorized users.

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Etoposide-induced apoptosis results in chromosome breaks within the <i>AF</i>9 gene: Its implication in chromosome rearrangement in leukaemia

Cited by 5 publications

References 44 publications

Matrix association region/scaffold attachment region: the crucial player in defining the positions of chromosome breaks mediated by bile acid-induced apoptosis in nasopharyngeal epithelial cells

Matrix association region/scaffold attachment region: the crucial player in defining the positions of chromosome breaks mediated by bile acid-induced apoptosis in nasopharyngeal epithelial cells

Inhibitor of caspase-activated DNase expression enhances caspase-activated DNase expression and inhibits oxidative stress-induced chromosome breaks at the mixed lineage leukaemia gene in nasopharyngeal carcinoma cells

Matrix association region/scaffold attachment region (MAR/SAR) sequence: its vital role in mediating chromosome breakages in nasopharyngeal epithelial cells via oxidative stress-induced apoptosis

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