Relevance of Carcinogen-Induced Preclinical Cancer Models

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The purpose of Sewduth’s et al article, Relevance of carcinogenic-induced preclinical cancer models, was to evaluate the possible use of a novel preclinical cancer model: carcinogenic-induced preclinical cancer models. This is an excellent review and I only have minor comments. The two traditional preclinical cancer models include transplanted and spontaneous. One significant drawback of using a transplanted preclinical motel is the inherent lack of interaction between the tumor and its microenvironment – a characteristic that does not occur in natural models. In contrast, carcinogenic-induced preclinical cancer models allow for much more dynamic interactions between the tumor cells, microenvironment, stromal and immune cells, hormones, cytokines, etc. Thus, this model potentially provides a much more complete picture of how a carcinogen, and eventually cancer, affects an animal model. Although transplanted models are easier to use, they do not reflect the dynamics of human tumors, as they may not accurately reflect the microenvironment. On the other hand, spontaneous models effectively regard evolution as well as immune responses. This model can be difficult to establish, but it is worth investing in as it closely relates to human responses. Additionally, through the various carcinogens explored in this review, it is established that not all carcinogens affect both animals and humans in an equal manner. Therefore, it is essential to optimize future approaches. The review includes immunohistochemistry to investigate mechanisms, but it would be beneficial to include quantifications. While the study did an excellent job showing the evidence of cancer following carcinogen exposure via histology (H&E staining specifically), additional quantitative tests such as cytokine arrays, Elisa, etc need to be conducted for both carcinogen-induced models and transplanted cancer cell models for more accurate comparison purposes – will there be a significant difference when both models are utilized? Overall, I believe this review is highly effective, and it is essential for scientists to understand the limitations of using models.  

Author Response

Overall, I believe this review is highly effective, and it is essential for scientists to understand the limitations of using models.  

We would like to thank the reviewer for the support. We believe that this is an important topic that would require more investment, in the future.

Concerning: additional quantitative tests such as cytokine arrays, Elisa, etc need to be conducted for both carcinogen-induced models and transplanted cancer cell models for more accurate comparison purpose.

As this is a review article, we cannot perform additional experiments. However, we performed the pathway analysis on available RNA sequencing datasets in murine models comparing naive organs to the one exposed to the different carcinogenic agents.  We believe that this approach gives an overview of the general changes observed in the different models.  For example, changes in the TNFalpha or Interferon Alpha, are observed in several of the models, in line with what would be expected in patients; 

This is an excellent review and I only have minor comments. The two traditional preclinical cancer models include transplanted and spontaneous. One significant drawback of using a transplanted preclinical motel is the inherent lack of interaction between the tumor and its microenvironment – a characteristic that does not occur in natural models. In contrast, carcinogenic-induced preclinical cancer models allow for much more dynamic interactions between the tumor cells, microenvironment, stromal and immune cells, hormones, cytokines, etc. Thus, this model potentially provides a much more complete picture of how a carcinogen, and eventually cancer, affects an animal model. Although transplanted models are easier to use, they do not reflect the dynamics of human tumors, as they may not accurately reflect the microenvironment. On the other hand, spontaneous models effectively regard evolution as well as immune responses. This model can be difficult to establish, but it is worth investing in as it closely relates to human responses. 

We have now rewritten the conclusion and discussion to highlight these very important points.

Reviewer 2 Report

Comments and Suggestions for Authors

The review discussed the pros and cons of several commonly used chemical carcinogens for the establishment of preclinical models. There are some major issues need to be addressed:

1. The manuscript follows the format of research articles, which is not suitable for review articles. For example, the section Materials and Methods should be removed. 

2. The content under the section Discussion resembles introduction but lacks a clear focus. There is no discussion relevant to the chemicals that has been covered. Similarly, in Conclusion section, the author actually talked about other carcinogens. 

3. There are several IHC figures that have caused confusion. Are they unpublished figures generated by the author or published ones cited by the author? If it is the former, more experimental details are needed in figure legends. Otherwise, the references should be provided. 

Comments on the Quality of English Language

Replace "carcinogenic-induced" with "Carcinogen-induced" in the Title

Author Response

1. The manuscript follows the format of research articles, which is not suitable for review articles. For example, the section Materials and Methods should be removed.

We have now removed the Materials and Methods section, and highlighted that this is a review article. 

2. The content under the section Discussion resembles introduction but lacks a clear focus. There is no discussion relevant to the chemicals that has been covered. Similarly, in Conclusion section, the author actually talked about other carcinogens. 

We have now restructured the conclusion and discussion sections, in  a more logical manner.

3. There are several IHC figures that have caused confusion. Are they unpublished figures generated by the author or published ones cited by the author? If it is the former, more experimental details are needed in figure legends. Otherwise, the references should be provided. 

To support the IHC, we have now added pathway analysis of changes at the mRNA levels, when comparing naive and carcinogenic treated tissue, that were reanalyzed from publicly available data (NCBI GEO). The reference for each dataset was added to each figure legend, and the doses specified. 

Comments on the Quality of English Language

Replace "carcinogenic-induced" with "Carcinogen-induced" in the Title

Thanks for this comment, and we modified the title accordingly. 

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have addressed the concerns. The paper is ready for publication.