Aryl Hydrocarbon Receptor (AhR) Signaling in Colonic Cells and Tumors

Round 1

Reviewer 1 Report

The main question addressed by the research is to find out the role of AhR and its ligands in colon tumors. AhR is a transcription factor that can be both a tumor suppressor and a promoter. Using different models of colon carcinogenesis, authors found that the AhR has oncosuppressive activity in the colon. These data complement the results of previous studies, which provided conflicting data, and support the hypothesis of an anticancer effect of AhR in colon cancer.

In addition, authors have clarified the mechanisms of the tumor suppressor activity of AhR.

Also, one of the conclusions of the authors is а possibility of clinical using of AhR selective modulators in the treatment of colon cancer.

Thus, the topic is relevant in the field and provides new information about AhR in relation to carcinogenesis. The conclusions are consistent with the evidence and arguments; the references are appropriate.

This interesting, important and well-presented article can be accepted for publication after one minor revision. Maybe it would be better to add the scheme of the experimental design for a clearer understanding

Author Response

A scheme summarizing the overall experimental design has now been added (Figure 2).

Reviewer 2 Report

Aryl hydrocarbon receptor (AhR) is widely expressed in many tissues including intestine. Authors describe the effect of AhR, the related mechanism and genes involved on the development of the colon tumors. AhR plays a role similar to the tumor suppressor dose in the colon.

General speaking, it is clear in the description of the concept. Figures are well-depicted.

The correspondence author is not indicated.

Author Response

Thank you for your review. Revisions have been made with your review in mind.

Reviewer 3 Report

This is a focussed review on the role of AHR for colonic tumors in mouse models as well as some in vitro models.

The topic is of interest, given that both genotoxins and AHR-ligands reach the body orally and affect the colon tumorigenesis.

The review is short and concise, but could be improved for better readability and to discern properly, where unpublished work of the authors is discussed. This is not evident in all cases, and can confuse readers. The following suggestions might be helpful

- give some background on the AOM/DSS method, i.e. the info necessary to understand why tumors develop in this model.

- the refs 5-9 are cited two times, first for "multiple endogenous functions", second for "structurally diverse ligands". Check if for functions better refs exist.

- Lines 74 ff: the treatment with AHR ligands should be specified, as the manuscript stresses that the nature of ligands has differing effects. Also the dose in feeding studies might be discussed. For instance, where indole3-carbinol is involved, high doses may be cancerogenic themselves.

- given the relevance of IL22, the paper of Gronke/Diefenbach might be discussed. Also, consider that in AHR-/- mice, the IL22 producing ILC and gd T cells are much reduced, and this may be relevant in all studies looking at cancer in AHR-/- mice. Thus, the role of inflammation and AHR in the gut immune system is not entirely clear, although mentioned. In organoids, the immune component is of course always missing, and it would be helpful to state or discuss it.

- The figures are not ideal. At a minimum, the figure legends need improvement and say on which paper(s) they are based.

- lines 124-128: this is one example where it is a bit unclear, if the author´s own, but yet unpublished work is described. If this is the case, be clear about it, and mayb even show data?

- The Summary is a bit too long, almost an abstract, it might be divided in summary and conclusion.

- add a few more references

-check manuscript for inclusion of all abbreviations (DIM, LGR5....) and for comma mistakes

Author Response

You have made some wonderful suggestions. In response to them, in the order from your review, please see the following:

-We have now added additional information on this model.

-The references have been rearranged.

-The doses have now been included and discussed. Our studies primarily focused on effect of AhR loss and ligand effects were primarily determined using TCDD.

-The background/relevance of IL22 producing ILC cells as well as the gut immune responses and their importance are now discussed.

-Figure legends are improved and referenced.

-This section has now been clarified.

-We have shortened the summary, added references throughout the revised manuscript and checked abbreviations.

Thank you for your detailed review.

Round 2

Reviewer 3 Report

The authors have changed the manuscript according to comments. The summary is still a bit long, but that is a matter of taste.

Author Response

Thanks