Résumé
OBJECTIVE@#To investigate the effects of an ethanol extract of Kalopanax septemlobus (Thunb.) Koidz. leaf (EEKS) on cell proliferation in human hepatocellular carcinoma cells and its mechanisms of action.@*METHODS@#Cells were treated with EEKS and subsequently analyzed for cell proliferation and flow cytometry analysis. Expressions of cell cycle regulators were determined by reverse transcriptase polymerase chain reaction analysis and Western blotting, and activation of cyclin-associated kinases studied using kinase assays.@*RESULTS@#The EEKS suppressed cell proliferation in both HepG2 and Hep3B cells, but showed a more sensitive anti-proliferative activity in HepG2 cells. Flow cytometry analysis revealed an association between the growth inhibitory effect of EEKS and with G1 phase cell cycle arrest in HepG2 cells, along with the dephosphorylation of retinoblastoma protein (pRB) and enhanced binding of pRB with the E2F transcription factor family proteins. Treatment with EEKS also increased the expression of cyclin-dependent kinase (CDK) inhibitors, such as p21WAF1/CIP1 and p27KIP1, without any noticeable changes in G1 cyclins and CDKs (except for a slight decrease in CDK4). Treatment of HepG2 cells with EEKS also increased the binding of p21 and p27 with CDK4 and CDK6, which was paralleled by a marked decrease in the cyclin D- and cyclin E-associated kinase activities.@*CONCLUSIONS@#Overall, our findings suggest that EEKS may be an effective treatment for liver cancer through suppression of cancer cell proliferation via G1 cell cycle arrest. Further studies are required to identify the active compounds in EEKS.
Résumé
Objective: To investigate the effects of an ethanol extract of Kalopanax septemlobus (Thunb.) Koidz. leaf (EEKS) on cell proliferation in human hepatocellular carcinoma cells and its mechanisms of action. Methods: Cells were treated with EEKS and subsequently analyzed for cell proliferation and flow cytometry analysis. Expressions of cell cycle regulators were determined by reverse transcriptase polymerase chain reaction analysis and Western blotting, and activation of cyclin-associated kinases studied using kinase assays. Results: The EEKS suppressed cell proliferation in both HepG2 and Hep3B cells, but showed a more sensitive anti-proliferative activity in HepG2 cells. Flow cytometry analysis revealed an association between the growth inhibitory effect of EEKS and with G
Résumé
BACKGROUND: p27 is a member of the cyclin-dependent kinase (CDK) inhibitors that arrest the progression of the cell cycle; thus, it acts as a tumor suppressor gene. The loss or decrease of p27 protein is frequently seen and this has an independent prognostic potential for many human cancers. p27 is functionally inactivated through accelerated proteolysis and cytoplasmic sequestration. Cytoplasmic mislocalization of p27 by abnormal phosphorylation in the tumor cells doesn't allow it to bind and inhibit nuclear cyclin/CDK targets. METHODS: We examined the p27 protein expression in 86 cases of invasive ductal carcinoma of the breast via immunohistochemical staining to evaluate the subcellular localization of p27 and its relationship with the clinicopathologic features and the prognostic factors. RESULTS: The nuclear expression of p27 was noted in 48.9% of the tumors, a combined nuclear and cytoplasmic expression was noted in 20.9%, a cytoplasmic expression was noted in 12.8%, and a negative expression was noted in 17.4%. The decreased nuclear expression and/or cytoplasmic mislocalization of p27 were statistically correlated with the nuclear grade (p=0.001), histologic grade (p=0.036), tumor size (p=0.033), lymph node metastasis (p=0.043), ER (p=0.001), and PR (p=0.001) status, while they were not correlated with patient age, stage, HER2, p53, and Ki67. CONCLUSIONS: The breast tumors showing both decreased nuclear expression and cytoplasmic mislocalization of p27 are associated with a deranged cell cycle via functional inactivation and also with poor prognostic factors. It is expected that p27 can be a promising anticancer target molecule for the treatment of breast cancer.