Zoledronic acid restores doxorubicin chemosensitivity and immunogenic cell death in multidrug-resistant human cancer cells
Authors: Dario Ghigo
Ivana Campia
Joanna Kopecka
Chiara Riganti
Marta Coscia
Barbara Castella
Massimo Massaia
Amalia Bosia
Gianpiero Pescarmona
Journal: PLoS ONE (2013)
Discipline: Multidisciplinary
Keywords: MDR; immunogenic cell death; mevalonate pathway; Ras; RhoA
Affiliations: Department of Oncology, University of Torino, Torino, Italy. 

Abstract:  Durable tumor cell eradication by chemotherapy is challenged by the development of multidrug-resistance (MDR) and the failure to induce immunogenic cell death. The aim of this work was to investigate whether MDR and immunogenic cell death share a common biochemical pathway eventually amenable to therapeutic intervention. We found that mevalonate pathway activity, Ras and RhoA protein isoprenylation, Ras- and RhoA-downstream signalling pathway activities, Hypoxia Inducible Factor-1alpha activation were significantly higher in MDR+ compared with MDR- human cancer cells, leading to increased P-glycoprotein expression, and protection from doxorubicin-induced cytotoxicity and immunogenic cell death. Zoledronic acid, a potent aminobisphosphonate targeting the mevalonate pathway, interrupted Ras- and RhoA-dependent downstream signalling pathways, abrogated the Hypoxia Inducible Factor-1alpha-driven P-glycoprotein expression, and restored doxorubicin-induced cytotoxicity and immunogenic cell death in MDR+ cells. Immunogenic cell death recovery was documented by the ability of dendritic cells to phagocytise MDR+ cells treated with zoledronic acid plus doxorubicin, and to recruit anti-tumor cytotoxic CD8+ T lymphocytes. These data indicate that MDR+ cells have an hyper-active mevalonate pathway which is targetable with zoledronic acid to antagonize their ability to withstand chemotherapy-induced cytotoxicity and escape immunogenic cell death. 

Retracted: Yes

PubPeer comments:
 Figure 6C. * Red boxes. Two flow cytometry panels appear to look similar, but the gated percentages differ.  This was reported to the journal in 2015, with a friendly reminder in 2016, but no response so far. , 
 Staring at Figure 6C a bit longer and 5 years later, I see some additional problems. The bottom 2 panels appear to show similarities as well. Marked with boxes in shades of blue.  , 
 Figure 5B. * Green arrows in three shades: Bands in the Ponceau panel appear to be visible multiple times. The one marked in lime green might be visible 6 times.  , 
 Figure 3C. * Red arrows: In the Input panel, lanes 1-3 look similar to lanes 4-6. * Yellow and orange boxes: Some similarities are noted in the background of the pro-mdr1 panel  , 
 #1 Dear Dr. Bik, First, please accept my apologies for my silence as corresponding author. The Editorial Office of PloS One alerted us only today about your comments. I am activating to retrieve the original materials and high-resolution images. Sincerely, Chiara Riganti , 
 Dear Dr. Riganti, Thank you for your reply. I hope you can find those materials and take away any concerns. Kind regards, Elisabeth Bik , 
 Retraction: Zoledronic Acid Restores Doxorubicin Chemosensitivity and Immunogenic Cell Death in Multidrug-Resistant Human Cancer Cells The PLOS ONE Editors Following the publication of this article [1], concerns were raised regarding results reported in Figs 2, 3, 4, 5, and 6. Specifically: Irregularities including straight horizontal and vertical distortions of the background and or repetitive elements in the background noise were detected in the panels listed below: u25cb. Fig 2D, GAPDH panel u25cb. Fig 3A, pHIF-1u03b1 panel and HIF-1u03b1 panel u25cb. Fig 3C, pro mdr1 panel u25cb. Fig 3D, GAPDH panel u25cb. Fig 4A, HIF-1u03b1 panel u25cb. Fig 4C, Pgp panel In Fig 3C, the first three lanes of the Input panel representing HT29 CTRL, HT29 ZA, and HT29-dx CTL appear similar to lanes 4u20136 representing HT29-dx ZA, HMM CTRL, and HMM ZA respectively. In Fig 5B, the following Ponceau staining results appear similar: u25cb. HT29 CTRL, HT29 ZA, HT29-dx CTRL, HT29-dx ZA, HMM CTRL, and HMM ZA u25cb. HT29 Dox, HT29-dx Dox, and HMM Dox u25cb. HT29 Dox+ZA, HT29-dx Dox+ZA, and HMM Dox+ZA The FACS panels representing DC DX CTRL and DC DX ZA in Fig 6C appear similar. In Fig 6C, the FACS results presented for DC DX Dox appear more similar to the FACS results for DC DX Dox+ZA than would be expected from independent FACS samples. The authors have provided higher resolution images of the published panels but indicated that the original data underlying the published results are no longer available. The data provided were not sufficient to resolve the concerns summarised above and raised further concerns pertaining the integrity of the blots presented in this article. In light of the concerns affecting multiple figure panels that question the integrity of these data, the PLOS ONE Editors retract this article. CR, BC, JK, MC, AB, and MM did not agree with the retraction. IC, GP, and DG either could not be reached or did not respond directly. , 
 The Editorial Office of Plos One asked in 2020 raw data and blots older than 7 years ago (lab movements, work changes, instruments changes, co-authors deaths occurred between 2013 and 2020: these were the Authors who did not respond). Editorial Policy of Plos ONE does not specify how long the Authors must retain the original raw data and blots. We are not clinical institutions, we are not obliged to mantain original data indefinitively. We are in defect because we did not retain the original blots, but in our opininion we believe that the management of PloS ONE on the article (asking original data after 7 years from publications) was not done properly. CR, BC, JK, AB and MM recognize their faults for not having providing the original data, but they did not agree with the retraction because we disagree with the PloS ONE management of the article. , 
 Dr. Riganti, I am sorry to hear about your co-author s co-authors death. I do, however, agree with the journal s decision to retract the paper. Looking at some of the duplications marked above, I doubt that showing us the original blots, gels, or raw data could have taken away any of my concerns. The similarities within or across panels is beyond what would be expected in an actual measurement. ,