Involvement of p53 and Nuclear Factor-kappaB Signaling Pathway for the Induction of G1-Phase Cell Cycle Arrest of Cholangiocarcinoma Cell Lines by Isomorellin

Abstract

Cell cycle arrest is closely linked to apoptosis. Isomorellin-a caged xanthone isolated from Garcinia hanburyi-induced apoptosis in cholangiocarcinoma (CCA) cell lines. To elucidate potential anticancer mechanisms, we investigated the effects of isomorellin on the growth, cell cycle progression, cell cycle regulated protein expression and nuclear factor-kappa B (NF-κB) activation of KKU-100 and KKU-M156 CCA cell lines; using sulforhodamine B assay, flow cytometry and Western blot analysis. The growth of both CCA cell lines was significantly inhibited by isomorellin treatment in a time-and dose-dependent manner. The respective IC 50 value of isomorellin for KKU-100 cells was 6.2 0.13, 5.1 0.11 and 3.5 0.25 µM at 24, 48 and 72 h. By comparison, the respective IC 50 value for KKU-M156 cells was 1.9 0.22, 1.7 0.14 and 1.5 0.14 µM at 24, 48 and 72 h. The growth inhibition of CCA cells by isomorellin was through the G0/G1 phase arrest mediated by inhibition of NF-κB activation, up-regulation of p53, p21 and p27 and down-regulation of cyclin D1, cyclin E, Cdk4 and Cdk2 protein levels. Our research suggests that isomorellin induces cell cycle arrest and apoptosis in CCA cell lines through p53 and the NF-κB-signaling pathway. The growth inhibitory potential of isomorellin was comparable to that of gambogic acid. Isomorellin shows potential as a therapeutic agent against human cholangiocarcinoma.

Antitumor effect of forbesione isolated from Garcinia hanburyi on cholangiocarcinoma in vitro and in vivo

“…This may possibly be due to high levels of p21 in forbesione-treated cells causing downregulation of PCNA, which results in decreased tumor cell proliferation (47). The present results are consistent with those of our previous study (21), which demonstrated that the isomorellin-induced G 0 /G 1 phase cell cycle arrest of human CCA cell lines is mediated through inhibition of NF-κB activation, upregulation of p53, p21 and p27, and downregulation of cyclin D1, cyclin E, Cdk2 and Cdk4 protein expression. However, the mechanisms of cell cycle arrest induced by forbesione are only partially understood, and additional experiments are required to provide conclusive answers.…”

“…KULTHIDA VAETEEWOOTTACHARN 3,6 and VICHAI REUTRAKUL selectively inhibited the proliferation of the human CCA cell lines KKU-100 and KKU-M156 by inducing apoptosis through the mitochondrial pathway (6), and by inducing G 0 /G 1 -phase cell cycle arrest through p53 and the nuclear factor (NF)-κB signaling pathway (21). Our previous studies demonstrated that combinations of isomorellin/doxorubicin and forbesione/doxorubicin exhibited significant synergy for inhibition of cell growth and induction of apoptosis in KKU-M156 and KKU-100 cells, respectively, through suppression of multidrug resistance-associated protein 1, NF-κB activation, enhanced expression of B-cell lymphoma (Bcl)-2-like protein 4 (Bax)/Bcl-2, activation of caspase-9 and caspase-3, and suppression of the expression of survivin, procaspase-9 and procaspase-3 (22).…”

“…In response to stimuli, IκB-α kinase (IKK) phosphorylates IκB, leading to its degradation, and consequently NF-κB translocates into the nucleus to activate the transcription of its target genes (40,65). Previous studies demonstrated that isomorellin and gambogic acid inhibit NF-κB activation through decreased NF-κB protein expression, and that the inhibition of IKK activation leads to suppressed phosphorylation and degradation of IκB-α as well as to the suppression of the nuclear translocation of NF-κB/p65 (17,21). The role of NF-κB in cell cycle progression has been previously reported (61).…”

Oncogenic Activity of Retinoic Acid Receptor γ Is Exhibited through Activation of the Akt/NF-κB and Wnt/β-Catenin Pathways in Cholangiocarcinoma

“…First, RAR␥ plays an active role in promoting cell proliferation and tumorigenicity, enhancing migration and invasion, and inducing multidrug resistance of CCA cells. Second, RAR␥ facilitated the G 1 /S transition; regulated P21 and cyclin D1, two critical cell cycle regulators (27); and upregulated the expression of the proliferation marker PCNA (28), which may contribute to tumor growth. Third, CCA is characterized by early metastasis (1), in which MMP-9 plays a critical role (29).…”

Inhibitory impacts of chemically modified tetracycline-3 and underlying mechanism in human cervical cancer cells

“…Recently, accumulating evidence has recommended that the ubiquitin-proteasome system plays a pivotal role in the cell cycle by mediating proteolysis [42]. Moreover, NF-kB has been considered as a critical modulator in the regulation of G 0 /G 1 cell cycle arrest [45]. In our study, CMT-3 significantly inhibited cyclin E expression instead of its transcription, indicating that the ubiquitin-proteasome system was probably involved in CMT-3-induced cell cycle arrest in Siha cells.…”