Review for 10.1186/1471-230X-13-29 (2013)

Reviewer's report
Title:A synergistic interaction between transcription factors nuclear
factor-kappaB and signal transducers and activators of transcription 3 promotes
gastric cancer cell migration and invasion
Version: 1Date:5 November 2012
Reviewer: brendan jenkins
Reviewer's report:
The upregulation of transcription factors, NF-#B and STAT3, has been implicated
in many cancers, including gastric cancer. This manuscript by Yoon et al aims to
bridge the gap between the crosstalk of these signaling molecules in gastric
cancer. More specifically, they showed that the inhibition of NF-#B reduced
STAT3 activation in a gastric cancer cell line (SNU-638), and inhibition of these
two signaling molecules significantly suppressed the metastatic potential of
SNU-638 cells. Overall, the manuscript is clearly written, however there are
several major concerns with the manuscript as presented, some of which include
unconvincing data and the lack thereof. With respect to this, this manuscript
requires major revisions and would not warrant publication unless these
concerns are addressed.
Specific comments:
Minor essential revisions
1) On page 10, the title of the first paragraph needs to be more informative to the
reader.
2) Figure 1, scale bars are missing.
Major compulsory revisions
3) While Figure 2 shows that SNU-638 cells over-expressing I#B#M displayed
reduced levels of STAT3 protein expression and activation, the mechanism by
which this is occurring has not been addressed. For instance, is NF-#B directly
regulating the transcription of STAT3 and are there any NF-#B binding sites in
the STAT3 promoter? To address this, STAT3 luciferase reporter assays should
be conducted. In addition, given that a study has shown that STAT3 and p65 can
heterodimerize to transcriptionally regulate NF-#B-dependent genes (Yang et al,
Genes and Development, 21, 1396-1408), it is therefore important to investigate
this by performing co-immunoprecipitation experiments on these cell lines.
Furthermore, the 2nd paragraph on page 13, the authors state that their findings
are consistent with Wani et al (2011), however they have not shown that IL-6 is
reduced in the SNU-638 cells over-expressing I#B#M, which may account for the
reduced STAT3 levels.
4) Figure 3B and 4B show that I#B#M and siSTAT3 over-expressing SNU-638
cells are significantly less invasive. Given that their immunoblot assays showed
that I#B#M and siSTAT3 reduced pRelA and pSTAT3 by approximately 50%,
respectively, the marginal decrease in the percentage of invasion does not look
convincing. Therefore, I would recommend showing these experiments in a
second gastric epithelial cell line.
5) While Figure 3C and 4C shows that EMT markers are altered in I#B#M and
siSTAT3 over-expressing SNU-638 cells, this was not looked at in SNU-638 cells
that over-express both I#B#M and siSTAT3. Since EMT is linked to cell migration
and invasion, and Figure 5B and 5C suggest that a reduction of pRelA and
pSTAT3 synergistically contributed to cell migration and invasion, it is important
to show that these EMT markers are also altered in SNU-638 cells that
over-express both I#B#M and siSTAT3.
Level of interest: An article of limited interest
Quality of written English: Acceptable
Statistical review: No, the manuscript does not need to be seen by a
statistician.
Declaration of competing interests:
I declare that i have no competing interests' below.