Reviewer's report
Title:The overmethylated genes in Helicobacter pylori-infected gastric mucosa
are demethylated in gastric cancers
Version: 1Date:30 July 2010
Reviewer: Yong Sung Kim
Reviewer's report:
The overmethylated genes in Helicobacter pylori infected gastric mucosa are
demethylated in gastric cancers.
The manuscript by Hong et al., presents evidence that the hypermethylated
genes under the influence of retroelement methylation in the HP-positive gastric
mucosae are demethylated in the gastric cancers influenced by LOH. Initially, to
delineate the CpG methylation patterns of CpG-island-containing and -lacking
genes in view of the retroelements, the methylation status were examined in the
transitional-CpG sites of CpG-island-containing genes and CpG-island-lacking
genes in HP-negative and -negative gastric mucosae or additional gastric cancer
tissues using MSP. They observed the CpG-island-containing genes were
hypermethylated depending on the proximity to the nearest retroelement in the
HP-positive gastric mucosa and the CpG-island-lacking genes were similarly
methylated independent on HP infection. And they also found that both the
methylation level of CpG-island-containing and -lacking genes tended to be
decreased according to LOH-level-dependent manner in gastric cancers.
Overall this is an impressive body of work on the different epigenetic regulation of
genes between CpG-island-containing house-keeping and -lacking stomach
specific genes during gastric carcinogenesis connecting to LOH event. The result
may provide an insight to understand the mechanism of epigenetic regulation for
the dynamic changes of methylation on different class of gene during gastric
carcinogenesis.
Comments:
Authors said that hypermethylated genes in HP-positive gastric mucosa are
demethylated in gastric cancers. They examined the HP infection in gastric
mucosae samples but not in gastric cancer samples. If the HP infection is
examined in gastric cancer samples and the methylation status is compared
between HP positive and negative, their opinion may be clearer. How do you
think about it?
Introduction section: the concept of the transitional-CpG sites has to be defined
for reader, though it has been described in the previous publications.
Page 7: In subsection of Collection of tissue samples, HP-positive or –negative
cases tested were described as each 50 cases. But actually authors analyzed
with 100 HP-positive and 100 HP-negative cases to examine the methylation
status, respectively. Correction is needed.
Page 8: In lane, ‘1,040’ µl may be a misprint. Correction is needed.
Level of interest: An article whose findings are important to those with closely
related research interests
Quality of written English: Needs some language corrections before being
published
Statistical review: No, the manuscript does not need to be seen by a
statistician.
Reviewer's report
Title:The overmethylated genes in Helicobacter pylori-infected gastric mucosa
are demethylated in gastric cancers
Version: 1Date:30 July 2010
Reviewer: Yong Sung Kim
Reviewer's report:
The overmethylated genes in Helicobacter pylori infected gastric mucosa are
demethylated in gastric cancers.
The manuscript by Hong et al., presents evidence that the hypermethylated
genes under the influence of retroelement methylation in the HP-positive gastric
mucosae are demethylated in the gastric cancers influenced by LOH. Initially, to
delineate the CpG methylation patterns of CpG-island-containing and -lacking
genes in view of the retroelements, the methylation status were examined in the
transitional-CpG sites of CpG-island-containing genes and CpG-island-lacking
genes in HP-negative and -negative gastric mucosae or additional gastric cancer
tissues using MSP. They observed the CpG-island-containing genes were
hypermethylated depending on the proximity to the nearest retroelement in the
HP-positive gastric mucosa and the CpG-island-lacking genes were similarly
methylated independent on HP infection. And they also found that both the
methylation level of CpG-island-containing and -lacking genes tended to be
decreased according to LOH-level-dependent manner in gastric cancers.
Overall this is an impressive body of work on the different epigenetic regulation of
genes between CpG-island-containing house-keeping and -lacking stomach
specific genes during gastric carcinogenesis connecting to LOH event. The result
may provide an insight to understand the mechanism of epigenetic regulation for
the dynamic changes of methylation on different class of gene during gastric
carcinogenesis.
Comments:
Authors said that hypermethylated genes in HP-positive gastric mucosa are
demethylated in gastric cancers. They examined the HP infection in gastric
mucosae samples but not in gastric cancer samples. If the HP infection is
examined in gastric cancer samples and the methylation status is compared
between HP positive and negative, their opinion may be clearer. How do you
think about it?
Introduction section: the concept of the transitional-CpG sites has to be defined
for reader, though it has been described in the previous publications.
Page 7: In subsection of Collection of tissue samples, HP-positive or –negative
cases tested were described as each 50 cases. But actually authors analyzed
with 100 HP-positive and 100 HP-negative cases to examine the methylation
status, respectively. Correction is needed.
Page 8: In lane, ‘1,040’ µl may be a misprint. Correction is needed.
Level of interest: An article whose findings are important to those with closely
related research interests
Quality of written English: Needs some language corrections before being
published
Statistical review: No, the manuscript does not need to be seen by a
statistician.
Please review this paper.
user
Reviewer's report
Title:The overmethylated genes in Helicobacter pylori-infected gastric mucosa
are demethylated in gastric cancers
Version: 1Date:30 July 2010
Reviewer: Yong Sung Kim
Reviewer's report:
The overmethylated genes in Helicobacter pylori infected gastric mucosa are
demethylated in gastric cancers.
The manuscript by Hong et al., presents evidence that the hypermethylated
genes under the influence of retroelement methylation in the HP-positive gastric
mucosae are demethylated in the gastric cancers influenced by LOH. Initially, to
delineate the CpG methylation patterns of CpG-island-containing and -lacking
genes in view of the retroelements, the methylation status were examined in the
transitional-CpG sites of CpG-island-containing genes and CpG-island-lacking
genes in HP-negative and -negative gastric mucosae or additional gastric cancer
tissues using MSP. They observed the CpG-island-containing genes were
hypermethylated depending on the proximity to the nearest retroelement in the
HP-positive gastric mucosa and the CpG-island-lacking genes were similarly
methylated independent on HP infection. And they also found that both the
methylation level of CpG-island-containing and -lacking genes tended to be
decreased according to LOH-level-dependent manner in gastric cancers.
Overall this is an impressive body of work on the different epigenetic regulation of
genes between CpG-island-containing house-keeping and -lacking stomach
specific genes during gastric carcinogenesis connecting to LOH event. The result
may provide an insight to understand the mechanism of epigenetic regulation for
the dynamic changes of methylation on different class of gene during gastric
carcinogenesis.
Comments:
Authors said that hypermethylated genes in HP-positive gastric mucosa are
demethylated in gastric cancers. They examined the HP infection in gastric
mucosae samples but not in gastric cancer samples. If the HP infection is
examined in gastric cancer samples and the methylation status is compared
between HP positive and negative, their opinion may be clearer. How do you
think about it?
Introduction section: the concept of the transitional-CpG sites has to be defined
for reader, though it has been described in the previous publications.
Page 7: In subsection of Collection of tissue samples, HP-positive or –negative
cases tested were described as each 50 cases. But actually authors analyzed
with 100 HP-positive and 100 HP-negative cases to examine the methylation
status, respectively. Correction is needed.
Page 8: In lane, ‘1,040’ µl may be a misprint. Correction is needed.
Level of interest: An article whose findings are important to those with closely
related research interests
Quality of written English: Needs some language corrections before being
published
Statistical review: No, the manuscript does not need to be seen by a
statistician.
assistant