periplocin and Colonic-Neoplasms

Cancer of the colon and rectum is the third most commonly diagnosed cancer and accounts for approximately 10% of all cancer-related deaths. Although surgical resection or radiotherapy are potentially curative for localized disease, advanced colon cancer is currently associated with poor prognosis. Therefore, the development of a new and effective chemotherapeutic agent is required to target critical pathways to induce responsiveness of colon cancer cells to death signals. Dysregulation of the beta-catenin/TCF pathway plays a central role in early activities of colorectal carcinogenesis. In this study, human colon cancer SW480 cells were used to investigate the effect of CPP (periplocin from Cortex periplocae) on the modulation of the beta-catenin/TCF signaling pathway. Our research results showed that CPP caused a dose- and time-dependent inhibition of cell growth as assessed by MTT assay and an induction in apoptosis as measured by flow cytometry and transmission electron microscopy. Furthermore, the CPP- treated cells were characterized by a decreased expression of beta-catenin protein in the total cell lysates and cytosolic and nuclear extracts. This expression alleviates the binding activity of T-cell factor (Tcf) complexes to its specific DNA-binding sites. Thus, the protein expression of the downstream elements survivin and c-myc was down-regulated. To determine the precise inhibitory mechanisms involved, further in-depth in vivo studies of CPP are warranted. In conclusion, our data suggest that CPP wields a multi-prong strategy to target the beta-catenin/Tcf signaling pathway, leading to the induction of apoptosis and inhibition of growth of colon cancer cells in vitro and in vivo. Therefore, CPP may become a potential agent against colon cancer.

Topics: Antineoplastic Agents, Phytogenic; beta Catenin; Carcinoma; Cell Proliferation; Colonic Neoplasms; Down-Regulation; Drug Evaluation, Preclinical; Gene Expression Regulation, Neoplastic; Genes, myc; Humans; Inhibitor of Apoptosis Proteins; Microtubule-Associated Proteins; Models, Biological; Periploca; Saponins; Signal Transduction; Survivin; TCF Transcription Factors; Tumor Cells, Cultured

The Wnt/beta-catenin signaling pathway plays an important role in the development and progression of human cancers, especially in colorectal carcinomas. This study was to analyze the inhibition effect of periplocin extracted from cortex periplocae (CPP) on proliferation of human colon carcinoma cell line SW480 and the underlying mechanism.. Cell proliferation of SW480 cells was measured by MTT assay. Cell apoptosis and cell cycle were analyzed by flow cytometry. Protein expression of beta-catenin in total cell lysates, cytosolic extracts, and nuclear extracts were detected by Western blot. Binding activity of the T cell factor (TCF) complex in nucleus to its specific DNA binding site was measured by electrophoretic mobility shift assay (EMSA). Expressions of beta-catenin, survivin, c-myc and cyclin D1 mRNA in cells after the treatment with CPP were detected by semi-quantitative RT-PCR.. CPP significantly inhibited the proliferation of SW480 cells in a time-and dose-dependent manner (P<0.01). CPP (0.5 microg/mL) also caused G0/G1 cell cycle arrest of SW480 cells and induced cell apoptosis (P<0.05). Compared to untreated control cells, after the treatment with CPP, the protein levels of beta-catenin in total cell lysates, cytosolic extracts, and nuclear extracts were reduced (P<0.01); the binding activity of the TCF complex in nucleus to its specific DNA binding site was suppressed; mRNAs of the downstream target genes survivin, c-myc and cyclin D1 were decreased (P<0.01) while beta-catenin mRNA remained unchanged.. CPP could significantly inhibit the proliferation of SW480 cells, which may be through down-regulating the Wnt/beta-catenin signaling pathway.

Topics: Antineoplastic Agents, Phytogenic; Apoptosis; beta Catenin; Cell Cycle; Cell Line, Tumor; Cell Proliferation; Colonic Neoplasms; Cyclin D1; Humans; Inhibitor of Apoptosis Proteins; Periploca; Proto-Oncogene Proteins c-myc; RNA, Messenger; Saponins; Signal Transduction; Survivin; TCF Transcription Factors; Wnt Proteins