ABSTRACT
Hepatocellular carcinoma (HCC) is a malignant tumor with poor prognosis and low therapeutic efficacy. Recent studies have demonstrated the therapeutic prospect of peroxisome proliferator-activated receptor-γ (PPARγ) cancer angiogenesis. However, the action mechanisms remain elusive. In the present study, by using mass spectrometry, we found that PPARγ ligand rosiglitazone (RGZ) could regulate HCC cell growth by influencing various downstream factors and pathways. Among the altered proteins, septin 2 (SEPT2) was found to exhibit oncogenic function. PPARγ overexpression could inhibit the expression of SEPT2, thus blocking the promoting effects of SEPT2 on HCC cell proliferation, invasion and its inhibitory effect on cell apoptosis. Further studies also indicated that SEPT2 promoted HCC cell growth via upregulation of matrix metalloproteinase (MMP)-2 and -9, and simultaneously inhibited the cleavage of caspase-3, -7, and -9. Interestingly, the effects of SEPT2 on the above factors could be suppressed by PPARγ overexpression, suggesting that PPARγ could inhibit HCC cell growth via regulating the expression and blocking the oncogenic function of SEPT2. Taken together, these results provide new evidence for the action mechanisms of PPARγ in carcinogenesis of HCC, and upon further investigation, PPARγ could be developed as a new target for the treatment of liver cancer.
Subject(s)
Antineoplastic Agents/pharmacology , Carcinoma, Hepatocellular/metabolism , Cell Proliferation/drug effects , Liver Neoplasms/metabolism , PPAR gamma/agonists , Septins/metabolism , Thiazolidinediones/pharmacology , Apoptosis/drug effects , Carcinoma, Hepatocellular/genetics , Carcinoma, Hepatocellular/pathology , Caspase 3/metabolism , Caspase 7/metabolism , Caspase 9/metabolism , Cell Movement/drug effects , Computational Biology , Down-Regulation , Electrophoresis, Gel, Two-Dimensional , Hep G2 Cells , Humans , Liver Neoplasms/genetics , Liver Neoplasms/pathology , Matrix Metalloproteinase 2/metabolism , Matrix Metalloproteinase 9/metabolism , Neoplasm Invasiveness , PPAR gamma/genetics , PPAR gamma/metabolism , Proteomics/methods , RNA Interference , Rosiglitazone , Septins/genetics , Signal Transduction/drug effects , Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization , TransfectionABSTRACT
BACKGROUND AND OBJECTIVE: Rosiglitazone is a peroxisome proliferators-activated receptor gamma (PPARgamma) ligand, which inhibits tumor growth by activating PPARgamma signaling pathways. Fluorouracil (5-FU) is one of the commonly used chemotherapeutic drugs. However, patients develop drug resistance of 5-FU over time. The aim of this study was to investigate whether rosiglitazone can enhance 5-FU-induced cell growth inhibition and to explore its potential mechanisms. METHODS: Cell viability was measured using MTT assay. Protein expression levels were detected by Western blot analysis. Small interference RNA was utilized to knockout PPARgamma and PTEN in Hep3B cells. RESULTS: After 48 h of treatment with 10, 20, and 40 µmol/L rosiglitazone, the viability of Hep3B cells was (78.0 ± 2.7)%, (37.3 ± 8.1)%, and (19.8 ± 2.2)%, respectively (compared with control group, P values were all < 0.001). After 48 h of treatment with 10 µmol/L 5-FU, the viability of Hep3B cells was about (82.6 ± 3.9)%. When cells were treated with 10 µmol/L 5-FU in combination with either 10, 20 or 40 µmol/L rosiglitazone, the cell viability was (51.6 ± 5.4)%, (14.8 ± 4.2)%, and (8.5 ± 0.9)%, with corresponding q value of 1.36, 1.23, and 1.19, respectively. These data suggested that the two drugs had synergic effect in inhibiting Hep3B cell growth, which was further confirmed in an in vivo mice model. Subsequent investigations showed that rosiglitazone activated PPARgamma signaling pathways and increased the expression of PTEN. CONCLUSIONS: Rosiglitazone enhances 5-FU-induced cell growth inhibition of Hep3B cells.