Brief Article
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World J Gastroenterol. Feb 7, 2014; 20(5): 1348-1356
Published online Feb 7, 2014. doi: 10.3748/wjg.v20.i5.1348
Oleanolic acid and ursolic acid inhibit proliferation in transformed rat hepatic oval cells
Yu-Ying Han, Xiao-Wei Xue, Zheng-Ming Shi, Peng-Yan Wang, Xin-Rui Wu, Xue-Jiang Wang
Yu-Ying Han, Department of Medical Genetics, Capital Medical University, Beijing 100069, China
Xiao-Wei Xue, Peng-Yan Wang, Xin-Rui Wu, Xue-Jiang Wang, Department of Pathology and Physiology, Capital Medical University, Beijing 100069, China
Zheng-Ming Shi, Department of Surgery, Beijing Jishuitan Hospital, Beijing 100035, China
Author contributions: Han YY and Xue XW designed and performed research; Shi ZM, Wang PY and Wu XR collected data and provided new reagents and analytic tools; Han YY and Wang XJ analyzed the data and performed statistical analyses; Wang XJ and Han YY wrote the paper; and all authors approved the final version to be published.
Supported by The Natural Science Foundation of Beijing Municipality, China, No. 7112010; the National Natural Science Foundation of China, No. 81272757; and the Education Commission Research Program of Beijing Municipality, China, No. KM201010025004
Correspondence to: Xue-Jiang Wang, Professor, Department of Pathology and Physiology, Capital Medical University, No. 10, You An Men Xi Tou Tiao, Beijing 100069, China. xj-w@163.com
Telephone: +86-10-83911434 Fax: +86-10-83911496
Received: September 9, 2013
Revised: November 6, 2013
Accepted: December 5, 2013
Published online: February 7, 2014
Abstract

AIM: To investigate H2O2-induced promotion proliferation and malignant transformation in WB-F344 cells and anti-tumor effects of ursolic acid (UA) and oleanolic acid (OA).

METHODS: WB-F344 cells were continuously exposed to 7 x 10-7 mol/L H2O2 for 21 d. Observations of cell morphology, colony formation rates, flow cytometric analysis of cell cycle changes and aneuploidy formation indicated that H2O2 was able to induce malignant transformation of WB-F344 cells. We treated malignantly transformed WB-F344 cells with 4 μmol/L OA or 8 μmol/L UA for 72 h and analyzed the cell cycle distribution by flow cytometry.

RESULTS: MTT assay showed that 7 x 10-7 mol/L H2O2 decreased G1 phase subpopulation from 73.8% to 49.6% compared with the control group, and increased S phase subpopulation from 14.5% to 31.8% (P < 0.05 vs control group). Cell morphology showed that nucleus to cytoplasm ratio increased, many mitotic cells, prokaryotes and even tumor giant cells were shown in H2O2-induced WB-F344 cells. Fluorescence activated cell sorting analysis showed that WB-F344 cell aneuploidy increased to 12% following H2O2 treatment. Flow cytometric analysis of the transformed WB-F344 cells following treatment with OA (4 μmol/L) and UA (8 μmol/L) showed that OA increased G1 subpopulation to 68.6%, compared to 49.7% in unexposed cells. UA increased G1 subpopulation to 67.4% compared to 49.7% in unexposed cells (P < 0.05 vs H2O2 model group).

CONCLUSION: H2O2 causes the malignant transformation of WB-F344 cells. OA and UA exert anti-tumor effects by inhibiting the proliferation in malignantly transformed WB-F344 cells.

Keywords: Oxidative stress, Hepatocarcinogenesis, Malignant transformation, Oleanolic acid, Ursolic acid

Core tip: It is known that H2O2 can promote tumorigenesis. Here, we used H2O2 as a premalignant and malignant agent to induce proliferation and malignant transformation in quiescent rat liver oval cell line WB-F344. Multistage carcinogenic processes provide the basis for interrupting and reversing precancerous changes; therefore, reversing precancerous changes is critical for tumor prevention and treatment. The salient and novel findings of the study are that ursolic acid (UA) and oleanolic acid (OA) induced malignantly transformed WB-F344 cell arrest in the G1 phase and apparently inhibited the proliferation of these cells. These results better our understanding of the antitumor effects of OA and UA.