A Small-Molecule Tankyrase Inhibitor Reduces Glioma Stem Cell Proliferation and Sphere Formation

Round 1

Reviewer 1 Report

The authors have addressed most of the points they were asked to. The manuscript has improved its quality after revision.

Author Response

Response to Reviewer 1

Thank you for the feedback. We are happy to hear that you believe the points were adequately addressed and that the manuscript has improved its quality after revision.

Reviewer 2 Report

The authors have improved the manuscript.  However they chose not to pursue several of the recommendations of the reviewers and this, in my opinion, requires further work.

The first reviewer was concerned about cytoplasmic contamination of actin and wanted to see nuclear actin levels.  The authors respond:

"As the reviewer correctly points out, a thorough separation between nuclear and cytoplasmic extracts is necessary for the interpretation of the data. Yet, while lamin is specific to the nucleus, actin is present both in the cytoplasm and the nucleus. Thus, this analysis would not demonstrate any low-level contamination. Even if such a contamination were present, it would not change the interpretation of the experiment."

I do not agree with ignoring this request and therefore this data is needed.

The second reviewer was concerned about the lack of in vivo data. The authors agree this would be helpful, but believe this is not needed for this paper.  Part of their justification was that it would be necessary to determine if the compound crosses the blood brain barrier.

This is exactly one of the concerns of reviewer 2.  If the compound does not cross the blood brain barrier, it will be of limited to no use.  Such compounds are not that valuable even with direct intracerebral injection, as it is difficult to deliver them to a glioma which has diffuse spread.

Therefore, while it will be more work, the authors should at least demonstrate that the compound can cross the blood brain barrier. 

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Author Response

Please see the attachment.

Author Response File: Author Response.pdf

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

The manuscript entitled ‘’A small-molecule tankyrase inhibitor reduces proliferation and sphere formation of glioma stem cells’’ by Kierulf-Vieira K.S. is a study that describes the effect of the small-molecule tankyrase inhibitor G007-LK on GSCs. The authors have tested this molecule in combination with temozolomide reporting sphere forming inhibition capacities interfering with the WNT/beta-catenin and Hippo pathways.

English language must be revised. Data must be better presented. In the graphs is always missing the control, which I suppose should be 100%. The authors should include a supplementary control bar in the graphs or a dotted line corresponding to 100%. Statistical analysis needs further attention and must be revised. Western blots must be quantificated. In those referring to nuclear extracts, actin levels are missing. This control is important in order to check cytoplasm contamination. It would be important for the reader to be reminded with the analysis about the molecular and stemness markers of primary cultures. Further, it would be helpful to know if the authors have any idea whether the different genetic assessment can explain the different behavior of the cultures used in the paper. The conclusion ‘’…additive reduction in sphere formation, but not proliferation, indicating that the two drugs in combination may target GSCs…’’ seems to be overestimated and needs further investigations.

Reviewer 2 Report

This is an interesting study of a potentially important target/pathway and the authors have done a good job beginning to study this in detail.

There are two issues with the paper.  The first is that it is very confusing that there is a reduction in YAP/TAZ genes, yet YAP nuclear protein accumulates.  This requires further investigation and elucidation.  The authors mention this issue, but do not really address it.

The study would be strengthened considerably by some in vivo data, using a PDX model.  There are many hypotheses about stem cells in GBM, and seeing an effect in vivo would strengthen the study and its conclusion.  Without this, the study is speculative and not powerful.