Cancer Cell paper under investigation following anonymous queries on PubPeer

A Cancer Cell paper that caused a flurry of activity on the website PubPeer is under investigation, after the last author announced on the site that he’d requested a correction from the journal.

The 2012 paper sparked a lively dialogue last month on the post-publication discussion site, as commenters questioned Western blot images in which some bands appeared to be duplicates. The last author responded, noting he had alerted the journal to a “mishap,” and a correction would be forthcoming. However, some commenters remained unsatisfied, and questioned why the correction was taking so long to appear, as well as the explanation for what went wrong.

A spokesman from Cancer Cell confirmed to us the paper is under investigation:

We are aware of the concerns raised regarding the Binda et al. paper published by Cancer Cell in 2012, and they are currently under investigation by the journal.  We do not think it would be appropriate to comment further until the investigation is concluded.

The article, titled “The EphA2 Receptor Drives Self-Renewal and Tumorigenicity in Stem-like Tumor-Propagating Cells from Human Glioblastomas,” ran in the December 2012 issue of Cancer Cell. It explores the relationship between a receptor, EphA2, and a subset of tumor-propagating cells, or TPCs, in invasive brain tumors. The study suggests that down-regulating EphA2 in certain invasive brain tumors, called glioblastomas, could curb TPCs’ ability to generate tumors.

There are tiers of commenters on PubPeer. People can register accounts with their own names, as the author did in the case of this comment stream. Researchers can also register and be verified by PubPeer, but appear on comment streams as Peer 1, Peer 2, etc. Finally, unregistered users can comment on PubPeer and they will be identified as such.

On December 2nd, anonymous commenter “Peer 1” posted a Western blot from the paper.

One of the authors, Angelo Vescovi from the University of Milan-Bicocca in Italy, responded on December 3rd that he knew the image was problematic:

The authors at Cancer Cell have been informed of this mishap. There were technical problem with the scanned picture database that led to misclassification of scanned plates images and misassembling and frame duplication, some of which were in fact non sensical and actually ended up lessening the cogency of our findings.

Vescovi also said that the paper’s authors provided the original images to the editors, the correction should be published soon, and the imaging error does not affect the findings.

That answer didn’t satisfy some commenters, who questioned the imaging mishap.

An unregistered user said,

Count me among those that are quite perplexed by this explanation. A ‘computer mishap’ and ‘misclassification’ somehow led to what are apparently duplicate bands in multiple positions on a single gel?? This would be really extraordinary.

Peer 1 asked when Vescovi sent the correction request to Cancer Cell — before or after the PubPeer comment stream.

“While your comments are very much taken into consideration, they had little to do with the production of an errata corrige on our side,” Vescovi said, adding that he notified Cancer Cell of the errors in early 2015.

We couldn’t confirm when Vescovi notified the journal. He did not respond to our request for comment, and the journal declined to provide that information.

While the date that researchers notified the journal is significant, the comment stream was never supposed to get that granular, according to Brandon Stell, the site’s founder, and an American neuroscientist at the University Paris Descartes.

He told us that questions on PubPeer must hold up to two criteria: “Comments have to be based on publicly verifiable information and they can’t be about the scientist themselves.” Because PubPeer enforces those two criteria, and because the site attracts niche readership, he said, “conversations generally don’t spiral out of control.”  In fact, since we contacted Stell about this piece, PubPeer moderators edited out parts of the conversation that, in his words, “got a little messy.”

Generally, Stell said that site moderators don’t know a comment stream has become inappropriate until they are alerted by site users.

Stell said he designed PubPeer, in part, to give authors a voice. Every time he participated in a group discussion of a paper, everyone involved had questions for the author, so he envisioned PubPeer as a way for authors to defend themselves.

Indeed, Vescovi had some words for his harshest critic, “Peer 1”:

You too are invited to my lab to see how reproducible [my results] are, I trust that our institution are not too far away from each other. though I understand that you may prefer to remain an unidentified critic.

I understand that this is allowed by this site but, frankly, I have little appreciation for this procedure and those whom decide to follow it. If comments are serene, [legitimate] and meant in everybody’s interest, why the need to post them anonymously?

Update 2/8/16 11:09 a.m. eastern: A commenter brought to our attention that the same day the comment thread on this paper began (December 2), Nature published a news story reporting how some scientists were criticizing Italian politicians for funding Vescovi’s stem cell trial:

The €3-million (US$3.2-million) pot for the trial should be allocated through an open competition based on scientific merit rather than in an amendment to the country’s 2016 budget bill, say the researchers. They are appealing to Italy’s Parliament to change the amendment — which the Senate approved on 20 November — before it passes into law.

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