Isoliquiritigenin induces apoptosis of human bladder cancer T24 cells via a cyclin-dependent kinase-independent mechanism
Authors: Yanming Wang
Xinyan Yan
Xinhui Yang
Qiusheng Zheng
Lingling Si
Journal: Oncology letters (2017)
Discipline: CLINICAL MEDICINE
Keywords: T24 cells; apoptosis; cyclin-dependent kinase 2; isoliquiritigenin.
Affiliations: School of Pharmacy, Shihezi University, Shihezi, Xinjiang 832002, P.R. China., Department of Pharmacy, The First Affiliated Hospital of the Medical College, Xinjiang Shihezi University, Shihezi, Xinjiang 832002, P.R. China.

Abstract:  The aim of the present study was to investigate whether an increase in cyclin-dependent kinase 2 (CDK2) activity is involved in apoptosis of human bladder cancer T24 cells induced by isoliquiritigenin (ISL). The viability of T24 cells was estimated using a sulforhodamine B assay. Cell morphological changes were examined using Hoechst 33258 staining. The apoptotic rate was determined by staining cells with Annexin V-fluorescein isothiocyanate and propidium iodide labeling. The mitochondrial membrane potential (ΔΨm) was measured using 5,5,6,6-tetrachloro-1,1, 3,3-tetraethyl benzimidazole carbocyanine iodide. Alterations in the apoptosis-related regulators B-cell lymphoma-2 (Bcl-2), Bcl-2-associated X protein (Bax), Bcl-2-interacting mediator of cell death (Bim), apoptotic protease-activating facter-1 (Apaf-1), caspase-9 and caspase-3 were determined using reverse transcription-polymerase chain reaction (PCR) and quantitative PCR methods. Western blot analysis was used to detect the expression of Bcl-2, Bax and caspase-3. CDK2 activity was measured using a spectrometric assay. Following treatment with ISL (between 30 and 70 µg/ml) for 24 h, typical apoptotic morphological changes were observed in T24 cells, exhibiting an edge set of chromosomes, nuclear condensation, nuclear fragmentation and other morphological features. Treatment with ISL increased the apoptotic ratio of T24 cells in a concentration-dependent manner and induced a decrease in the ΔΨm in a time-dependent manner. Treatment with ISL upregulated the expression of Bax, Bim, Apaf-1, caspase-9 and caspase-3, downregulated the expression of Bcl-2, and increased CDK2 activity. MK-8776 (an inhibitor of CDK2) antagonized the apoptosis induced by ISL, and, compared with treatment with ISL alone, pretreatment with MK-8776 inhibited the decrease in ΔΨm, downregulated the mRNA expression of Bax, Bim, Apaf-1, caspase-9 and caspase-3, and upregulated Bcl-2 mRNA expression. Western blot analysis demonstrated that, with increasing ISL concentration, the Bcl-2 expression level was significantly decreased (P&lt;0.05), whereas caspase-3 and Bax expression levels were significantly increased (P&lt;0.01). These results indicated that ISL treatment caused a significant decrease in the proliferation rate and increase in apoptosis of T24 cells. The mechanism by which ISL induces T24 cell apoptosis in vitro may be associated with an increase in CDK2 activity, downregulation of the ΔΨm and activation of caspase-3/caspase-9-mediated mitochondrial apoptotic signaling pathways. 

Retracted: No

PubPeer comments:
 Image concerns in this paper were found during a systematic search of papers in Spandidos journals for possible duplicated images. Figure 10. Red boxes: Lanes 2-3 in the Bcl-2 panel appear to look similar to lanes 1-2 in the Caspase-9 panel. ![file] , 
 Corrigendum, February 2021: https: www.spandidos-publications.com 10.3892 ol.2021.12529  Subsequently to the publication of this paper, an interested reader drew to the authorsu2019 attention that, in Fig. 10, lanes 2u20133 in the Bcl-2 panel appeared to be strikingly similar to lanes 1u20132 in the Caspase-9 panel. The authors have re-examined their data and realized that Fig. 10 was assembled incorrectly; essentially, the data for the Bcl-2 and Caspase-9 bands, which were similar in actual appearance, were confused during the final compilation of the Figure. The revised version of Fig. 10, containing the correct data for the Caspase-9 experiment, is shown below. The authors regret the error that was inadvertently made in the preparation of the Figure, and confirm that this error did not seriously affect the conclusions reported in the paper. The authors are grateful to the editor of Oncology Letters for allowing them the opportunity to publish a Corrigendum, and all the authors agree to this Corrigendum. Furthermore, they apologize to the readership for any inconvenience caused. ,