ABSTRACT
Paclitaxel is one of the best anticancer agents that has been isolated from plants, but its major disadvantage is its dose-limiting toxicity. In this study, we obtained evidence that the active mutant IPP5 (8-60hIPP5m), the latest member of the inhibitory molecules for protein phosphatase 1, sensitizes human cervix carcinoma cells HeLa more efficiently to the therapeutic effects of paclitaxel. The combination of 8-60hIPP5m with paclitaxel augmented anticancer effects as compared to paclitaxel alone as evidenced by reduced DNA synthesis and increased cytotoxicity in HeLa cells. Furthermore, our results revealed that 8-60hIPP5m enhances paclitaxel- induced G2/M arrest and apoptosis, and augments paclitaxel-induced activation of caspases and release of cytochrome C. Evaluation of signaling pathways indicated that this synergism was in part related to down- regulation of NF-?B activation and serine/threonine kinase Akt pathways. We noted that 8-60hIPP5m down- regulated the paclitaxel-induced NF-?B activation, I?Bα degradation, PI3-K activity and phosphorylation of the serine/threonine kinase Akt, a survival signal which in many instances is regulated by NF-?B. Together, our observations indicate that paclitaxel in combination with 8-60hIPP5m may provide a therapeutic advantage for the treatment of human cervical carcinoma.
Subject(s)
Antineoplastic Agents, Phytogenic/pharmacology , Drug Tolerance/genetics , Mutation/genetics , Paclitaxel/pharmacology , Proteins/genetics , Uterine Cervical Neoplasms/drug therapy , Uterine Cervical Neoplasms/genetics , Apoptosis/drug effects , Blotting, Western , Caspases/metabolism , Cell Cycle/drug effects , Cell Proliferation/drug effects , Drug Synergism , Female , Humans , NF-kappa B/metabolism , Phosphorylation/drug effects , Proto-Oncogene Proteins c-akt/metabolism , Signal Transduction , Tumor Cells, Cultured , Uterine Cervical Neoplasms/pathologyABSTRACT
To investigate the anti-proliferative mechanism of mangiferin in a human nasopharyngeal carcinoma cell line, CNE2 cells were incubated with different concentrations of mangiferin (12.5, 25, 50, 100, 150 and 200 µM) or with PBS as a control for 72 hours. Analyses were made of the cell cycle and apoptosis with measurement of mRNA and protein levels of two apoptosis-related genes, Bcl-2 and Bax. Flow cytometry assays showed mangiferin could inhibit CNE2 cell proliferation via G2/M arrest and induction of early apoptosis. Real time PCR and Western blotting showed the mRNA and protein level of Bcl-2 to be down-regulated, while those of Bax were up-regulated, when CNE2 cells were treated with mangiferin. This investigation indicated anti-proliferation effects of mangiferin through induction of cell apoptosis regulated by Bcl-2 and Bax expression.
Subject(s)
Apoptosis/drug effects , Cell Proliferation/drug effects , Gene Expression Regulation, Neoplastic/drug effects , Nasopharyngeal Neoplasms/metabolism , Proto-Oncogene Proteins c-bcl-2/drug effects , RNA, Messenger/metabolism , Xanthones/pharmacology , bcl-2-Associated X Protein/drug effects , Carcinoma , Cell Cycle Checkpoints/drug effects , Cell Line, Tumor , Genes, bcl-2/drug effects , Humans , Nasopharyngeal Carcinoma , Proto-Oncogene Proteins c-bcl-2/metabolism , Reverse Transcriptase Polymerase Chain Reaction , bcl-2-Associated X Protein/genetics , bcl-2-Associated X Protein/metabolismABSTRACT
RT-qPCR is a commonly used method for evaluating gene expression; however, its accuracy and reliability are dependent upon the choice of appropriate reference gene(s), and there is limited information available on suitable reference gene(s) that can be used in mouse testis at different stages. In this study, using the RT-qPCR method, we investigated the expression variations of six reference genes representing different functional classes (Actb, Gapdh, Ppia, Tbp, Rps29, Hprt1) in mice testis during embryonic and postnatal development. The expression stabilities of putative reference genes were evaluated using five algorithms: geNorm, NormFinder, Bestkeeper, the comparative delta C(t) method and integrated tool RefFinder. Analysis of the results showed that Ppia, Gapdh and Actb were identified as the most stable genes and the geometric mean of Ppia, Gapdh and Actb constitutes an appropriate normalization factor for gene expression studies. The mRNA expression of AT1 as a test gene of interest varied depending upon which of the reference gene(s) was used as an internal control(s). This study suggested that Ppia, Gapdh and Actb are suitable reference genes among the six genes used for RT-qPCR normalization and provide crucial information for transcriptional analyses in future studies of gene expression in the developing mouse testis.
Subject(s)
Gene Expression , Real-Time Polymerase Chain Reaction/standards , Testis/metabolism , Algorithms , Animals , DNA Primers , Male , Mice , Receptor, Angiotensin, Type 1/genetics , Reference Standards , Testis/embryology , Testis/growth & developmentABSTRACT
Protein phosphatase 1 (PP1) is a major serine/threonine phosphatase that controls gene expression and cell cycle progression. The active mutant IPP5 (8-60hIPP5(m)), the latest member of the inhibitory molecules for PP1, has been shown to inhibit the growth of human cervix carcinoma cells (HeLa). In order to elucidate the underlying mechanisms, the present study assessed overexpression of 8-60hIPP5(m) in HeLa cells. Flow cytometric and biochemical analyses showed that overexpression of 8-60hIPP5(m) induced G2/M-phase arrest, which was accompanied by the upregulation of cyclin B1 and phosphorylation of G2/M-phase proteins ATM, p53, p21(cip1/waf1) and Cdc2, suggesting that 8-60hIPP5(m) induces G2/M arrest through activation of the ATM/p53/p21(cip1/waf1)/Cdc2/ cyclin B1 pathways. We further showed that overexpression of 8-60hIPP5(m) led to delayed nuclear translocation of cyclin B1. 8-60hIPP5(m) also could translocate to the nucleus in G2/M phase and interact with pp1α and Cdc2 as demonstrated by co-precipitation assay. Taken together, our data demonstrate a novel role for 8-60hIPP5(m) in regulation of cell cycle in HeLa cells, possibly contributing to the development of new therapeutic strategies for cervix carcinoma.
