S100B-p53 disengagement by pentamidine promotes apoptosis and inhibits cellular migration via aquaporin-4 and metalloproteinase-2 inhibition in C6 glioma cells
Authors: Elena Capoccia
Annalisa Marchetto
Samanta Tiberi
Carla Cirillo
Youssef Sawikr
Luca Steardo
Caterina Scuderi
Giovanni Sarnelli
Rosario Cuomo
Marcella Pesce
Alessandra D&#x27;Alessandro
Giuseppe Esposito
Journal: Oncology Letters (2015)
Discipline: CLINICAL MEDICINE
Keywords: S100 calcium-binding protein B; glioma cells; p53; pentamidine.
Affiliations: Department of Physiology and Pharmacology 'Vittorio Erspamer', Sapienza University of Rome, Rome I-00185, Italy., Laboratory for Enteric Neuroscience, Translational Research Center for Gastrointestinal Disorders, University of Leuven, Leuven 3000, Belgium., Department of Clinical and Experimental Medicine, Gastroenterology Unit, University of Naples Federico II, Naples I-80131, Italy.

Abstract:  S100 calcium-binding protein B (S100B) is highly expressed in glioma cells and promotes cancer cell survival via inhibition of the p53 protein. In melanoma cells, this S100B-p53 interaction is known to be inhibited by pentamidine isethionate, an antiprotozoal agent. Thus, the aim of the present study was to evaluate the effect of pentamidine on rat C6 glioma cell proliferation, migration and apoptosis in vitro. The change in C6 cell proliferation following treatment with pentamidine was determined by performing a 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide-formazan assay. Significant dose-dependent decreases in proliferation were observed at pentamidine concentrations of 0.05 ¬µM (58.5¬±5%; P&lt;0.05), 0.5 ¬µM (40.6¬±7%; P&lt;0.01) and 5 ¬µM (13¬±4%; P&lt;0.001) compared with the control (100% viability). Furthermore, treatment with 0.05, 0.5 and 5 ¬µM pentamidine was associated with a significant increase in apoptosis versus the untreated cells, as determined by DNA fragmentation assays, immunofluorescence analysis of C6 chromatin using Hoechst staining, and immunoblot analysis of B-cell lymphoma-2 (Bcl-2)-associated X protein (100%, P&lt;0.05; 453%, P&lt;0.01; and 1000%, P&lt;0.001, respectively) and Bcl-2 (-60%, P&lt;0.001; -80.13%, P&lt;0.001; -95%, P&lt;0.001, respectively). In addition, the administration of 0.05, 0.5 and 5 ¬µM pentamidine significantly upregulated the protein expression levels of p53 (681¬±87.5%, P&lt;0.05; 1244¬±94.3%, P&lt;0.01; and 2244¬±111%, P&lt;0.001, respectively), and significantly downregulated the expression levels of matrix metalloproteinase-2 (42¬±2.3%, P&lt;0.05; 71¬±2.5%, P&lt;0.01; and 95.8¬±3.3%, P&lt;0.001, respectively) and aquaporin 4 (38¬±2.5%, P&lt;0.05; 69¬±2.6%, P&lt;0.01; and 88¬±3.0%, P&lt;0.001, respectively), compared with the untreated cells. The wound healing assay demonstrated that cell migration was significantly impaired by treatment with 0.05, 0.5 and 5 ¬µM pentamidine compared with untreated cells (88¬±4.2%, P&lt;0.05; 64¬±2%, P&lt;0.01; and 42¬±3.1%, P&lt;0.001, respectively). Although additional in vivo studies are required to clarify the current in vitro data, the present study indicates that pentamidine and S100B-p53 inhibitors may represent a novel approach for the treatment of glioma. 

Retracted: No

PubPeer comments:
 The images shown below need attention by the authors   , 
 A previous comment by an anonymous peer was removed by the moderators, but after looking at Figure 1, I do have questions for the authors. Can you explain the sharp edges visible in a number of the images? These do not seem to be compression artifacts, in my opinion. Shown below with enhanced contrast and inverted. ***  ***  , 
 Despite being brave enough to hypothesize about the neurological effects of COVID-19 in the [popular press] , the penultimate author remains silent when readers question their published research - perhaps fearful of the consequences of serious scrutiny? ***  ,