Crocin, a carotenoid, suppresses spindle microtubule dynamics and activates the mitotic checkpoint by binding to tubulin
Authors: Bhabatarak Bhattacharyya
Shalini Srivastava
Avishkar V Sawant
Shweta S Prassanawar
Dulal Panda
Journal: Biochemical pharmacology (2019)
Discipline: PHARMACOLOGY & TOXICOLOGY
Keywords: Combination therapy; Crocin; Microtubule dynamics; Microtubule-targeting agent; Tubulin.
Affiliations: Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai 400076, India., Department of Biochemistry, Bose Institute, Centenary Campus, Kolkata 700054, India., Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai 400076, India. Electronic address: .

Abstract:  Crocin, a constituent of the saffron spice, exhibits promising antitumor activity in animal models and also inhibits the proliferation of several types of cancer cells in culture. Recently, we have shown that crocin binds to purified tubulin at the vinblastine site, depolymerizes microtubules and induces a mitotic block in cultured cells. Here, we extend our previous suggestion and explore the cellular effects of crocin to further understand its mechanism of action. In a kinetic study, we observed that the crocin-induced depolymerization of microtubules preceded both DNA damage and reactive oxygen species generation indicating that depolymerizing microtubules is the primary action of crocin. Crocin also inhibited the growth of cold-depolymerized microtubules in HeLa cells indicating that it can inhibit microtubule dynamics. Using fluorescence recovery after photobleaching, crocin was found to suppress the spindle microtubule dynamics in live HeLa cells. Further, crocin treatment resulted in activation of spindle assembly checkpoint proteins, BubR1 and Mad2. Similar to other microtubule-targeting agents, crocin also perturbed the localization of end-binding protein EB1 from the growing microtubule ends and enhanced the acetylation of remaining microtubules. Further, crocin was found to bind to purified tubulin with a dissociation constant of 12 ± 1.5 μM. The results suggested that crocin exerted its antiproliferative effect primarily by inhibiting the assembly and dynamics of microtubules. Importantly, the combination of crocin with known anticancer agents like combretastatin A-4, cisplatin, doxorubicin or sorafenib, exerted a strong synergistic cytotoxic effect in HeLa cells indicating that crocin may enhance the effectiveness of other anticancer agents. 

Retracted: No

PubPeer comments:
 Figure 4A. * Red boxes: In the top row the 0h and 2h panels look very similar. * Aqua boxes: In the bottom row, the 0h and 6h panels look very similar. ![file] , 
 #1 Thank you for bringing this error to our attention. We deeply appreciate it as it has allowed us to rectify an inadvertent mistake from our part. We are very sorry about it. The error was due to a wrong file being exported and unintentionally pasted twice during the preparation of the figure. Unfortunately, we failed to notice the mistake because of the similarity of the panels. We have sent a corrected Figure 4A and 3 independent sets of raw data files for Figure 4A to Biochemical Pharmacology. We requested the journal editor to replace the wrong figure 4A with a correct figure. Kindly note that the mistake does not have any effect on the quantification and analysis of the data. Sincerely, Dulal Panda , 
 Corrigendum, May 2020: https: www.sciencedirect.com science article pii S0006295220302185  The authors would like to point out some inadvertent errors in Fig. 4A. We would like to replace Fig. 4A as some panels were unintentionally pasted twice during the preparation of the figure. Kindly note that the mistake does not have any effect on the quantification and analysis of the data. Thus, the change does not have any implications on the final results of the paper. The authors sincerely apologize for any inconvenience caused. The corrected figure is below: ![file] , 
 Of note, the corrected version is completely different than the originally published figure. Could the authors clarify if they could not find the original data anymore of a paper that was only 1 year old? I am not sure why the not just the misplaced panels were replaced with the correct panels. It is of concern that those originals were not available anymore. , 
 Thank you for your query. We had provided raw flow cytometer images for figure 4A in the corrigendum, while the published paper had images that were processed and analyzed using FlowJo software. Although we should have replaced the two misplaced panels with their processed images like in the published paper, we had to use raw data as we were unable to process the data files of the two panels since our institute was closed indefinitely at that time due to the Covid19 pandemic, and we had no access to the software. Importantly, we had no idea at that time when the institute would be operational. Therefore, we decided to replace the entire figure panel 4A with the corresponding raw data for each time point and changed the misplaced panels. Hence, the appearance of the panels in the corrigendum is slightly different from the original figure. While submitting the corrigendum, we submitted the data to the journal. We also have the original data with us. We used the raw data in the corrigendum instead of the FlowJo software processed images because we had no access to the software during the pandemic and we wanted to correct the mistake immediately. ,