cyclin-d1 and cryptotanshinone

Cryptotanshinone (CPT) is a natural compound extracted from herbal medicine that has been previously shown to possess antitumor properties in various types of human cancer cells. In the present study, we examined the potential role of CPT in the treatment of colorectal cancer. Using SW480, HCT116, and LOVO colorectal cancer cell lines, the effects of CPT on cell viability, apoptosis, and tumorigenicity were evaluated. The results showed that CPT significantly inhibited the growth and viability of SW480, HCT116, and LOVO cell lines by inducing apoptosis and prevented anchorage dependent growth on agar. In addition, CPT inhibited the activation of Signal transducer and activator of transcription 3 (Stat3) pathways in colorectal cancer cells. Stat3 is a transcription factor that mediates the expression of various genes associated with many cellular processes, such as inflammation and cell growth, and has been shown to promote several cancer types, including colorectal cancer. These findings indicate that CPT may be a potential candidate for the treatment and prevention of colorectal cancer in part by inhibiting the activation of Stat3.

Topics: Antineoplastic Agents, Phytogenic; Apoptosis; Cell Proliferation; Cell Survival; Colorectal Neoplasms; Cyclin D1; Cyclin-Dependent Kinase Inhibitor p21; Cyclin-Dependent Kinase Inhibitor p27; Drug Screening Assays, Antitumor; HCT116 Cells; Humans; Inhibitor of Apoptosis Proteins; Phenanthrenes; STAT3 Transcription Factor; Survivin

To investigate the anti-angiogenic effect of cryptotanshinone (CPT) on human umbilical vein endothelial cells (HUVECs) and the effect of CPT on Wnt/β-catenin signaling pathway.. HUVECs were incubated with 0, 2.5, 5, 10, and 20 μ mol/L CPT for detecting cell viability with dimethyl thiazolyl-2,5-diphenyltetrazolium bromide (MTT) assay. Then, HUVECs were incubated with 0, 2.5, 5, and 10 μ mol/L CPT for detecting endothelial cell migration, invasion, and tubular-like structure formation with wound healing, transwell invasion and matrigel tube formation assays, respectively. To gain insight into CPT-mediated signaling, the effects of CPT on T-cell factor/lymphocyte enhancer factor (TCF/LEF) transcription factors were detected by the Dual-luciferase reporter assay. Next, the nuclear expression of β-catenin was evaluated using Western blot and immunochemistry. Finally, vascular endothelial growth factor (VEGF) and cyclin D1, downstream proteins of the Wnt pathway were examined with Western blot.. CPT dose-dependently suppressed endothelial cell viability, migration, invasion, and tubular-like structure formation. In particular, CPT blocked β-catenindependent transcription in HUVECs in a dose-dependent manner. In Western bolt, 10 μ mol/L CPT decreased expression of β-catenin in nucleus of HUVECs (P<0.01). In immunohistochemistry, β-catenin was more potent in response to LiCl (an activator of the pathway) treatment. However, the signals were weaker in the nucleus of the CPT (10 μ mol/L) group, compared to the positive control. Also, VEGF and cyclin D1 were both eliminated by CPT in 5 and 10 μ mol/L doses (P<0.05).. Our study supported the role of CPT as an angiogenic inhibitor, which may impact on the Wnt/β-catenin signaling pathway.

Topics: beta Catenin; Blotting, Western; Cell Movement; Cell Survival; Cyclin D1; Human Umbilical Vein Endothelial Cells; Humans; Immunohistochemistry; Luciferases; Neovascularization, Physiologic; Phenanthrenes; Vascular Endothelial Growth Factor A; Wnt Signaling Pathway

Cryptotanshinone (CPT), a diterpene quinone isolated from Salvia miltiorrhiza, is recently reported to have obvious anticancer activities against diverse cancer cells. However, the effect and regulatory mechanism of CPT remain unclear in human chronic myeloid leukemia (CML) cells. In this study, we investigated the antiproliferative activity of CPT on the multidrug resistant CML cells K562/ADM. Our results demonstrated that CPT decreased the cell viability of K562/ADM cells by inducing cell cycle arrest and apoptosis through suppressing the expression of cyclin D1 and Bcl-2. Further studies indicated that CPT mainly functions at post-transcriptional levels, suggesting the involvement of eukaryotic initiation factor 4E (eIF4E). CPT significantly reduced the expression and activity of eIF4E in K562/ADM cells. Overexpression of eIF4E obvious conferred resistance to the CPT antiproliferation and proapoptotic activity as well as the cyclin D1 and Bcl-2 expressions. Knockdown of eIF4E significantly reduced the inhibitory effect of CPT in K562/ADM, confirming the participation of eIF4E during CPT function process. More importantly, the relative inhibitory efficiency of CPT positively correlated with the reductions on eIF4E in primary CML specimens. These results demonstrated that CPT played antitumor roles in K562/ADM cells by inhibiting the eIF4E regulatory system. Our results provide a novel anticancer mechanism of CPT in human CML cells.

Topics: Apoptosis; Cell Cycle Checkpoints; Cyclin D1; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Eukaryotic Initiation Factor-4E; Gene Expression Regulation, Leukemic; Gene Knockdown Techniques; Humans; K562 Cells; Leukemia, Myelogenous, Chronic, BCR-ABL Positive; Peptide Chain Initiation, Translational; Phenanthrenes; Proto-Oncogene Proteins c-bcl-2

Cryptotanshinone (CPT), a natural compound isolated from the plant Salvia miltiorrhiza Bunge, is a potential anticancer agent. However, little is known about its anticancer mechanism. Here, we show that CPT inhibited cancer cell proliferation by arresting cells in G(1)-G(0) phase of the cell cycle. This is associated with the inhibition of cyclin D1 expression and retinoblastoma (Rb) protein phosphorylation. Furthermore, we found that CPT inhibited the signaling pathway of the mammalian target of rapamycin (mTOR), a central regulator of cell proliferation. This is evidenced by the findings that CPT inhibited type I insulin-like growth factor I- or 10% fetal bovine serum-stimulated phosphorylation of mTOR, p70 S6 kinase 1, and eukaryotic initiation factor 4E binding protein 1 in a concentration- and time-dependent manner. Expression of constitutively active mTOR conferred resistance to CPT inhibition of cyclin D1 expression and Rb phosphorylation, as well as cell growth. The results suggest that CPT is a novel antiproliferative agent.

Topics: Antineoplastic Agents; Cell Proliferation; Cyclin D1; Down-Regulation; Drug Evaluation, Preclinical; Drug Resistance, Neoplasm; Gene Expression Regulation, Neoplastic; Humans; Neoplasms; Phenanthrenes; Phosphorylation; Protein Kinases; Retinoblastoma Protein; TOR Serine-Threonine Kinases; Tumor Cells, Cultured

Because signal transducer and activator of transcription 3 (STAT3) is constitutively activated in most human solid tumors and is involved in the proliferation, angiogenesis, immune evasion, and antiapoptosis of cancer cells, researchers have focused on STAT3 as a target for cancer therapy. We screened for natural compounds that inhibit the activity of STAT3 using a dual-luciferase assay. Cryptotanshinone was identified as a potent STAT3 inhibitor. Cryptotanshinone rapidly inhibited STAT3 Tyr705 phosphorylation in DU145 prostate cancer cells and the growth of the cells through 96 hours of the treatment. Inhibition of STAT3 Tyr705 phosphorylation in DU145 cells decreased the expression of STAT3 downstream target proteins such as cyclin D1, survivin, and Bcl-xL. To investigate the cryptotanshinone inhibitory mechanism in DU145 cells, we analyzed proteins upstream of STAT3. Although phosphorylation of Janus-activated kinase (JAK) 2 was inhibited by 7 micromol/L cryptotanshinone at 24 hours, inhibition of STAT3 Tyr705 phosphorylation occurred within 30 minutes and the activity of the other proteins was not affected. These results suggest that inhibition of STAT3 phosphorylation is caused by a JAK2-independent mechanism, with suppression of JAK2 phosphorylation as a secondary effect of cryptotanshinone treatment. Continuing experiments revealed the possibility that cryptotanshinone might directly bind to STAT3 molecules. Cryptotanshinone was colocalized with STAT3 molecules in the cytoplasm and inhibited the formation of STAT3 dimers. Computational modeling showed that cryptotanshinone could bind to the SH2 domain of STAT3. These results suggest that cryptotanshinone is a potent anticancer agent targeting the activation STAT3 protein. It is the first report that cryptotanshinone has antitumor activity through the inhibition of STAT3.

Topics: bcl-X Protein; Breast Neoplasms; Cell Growth Processes; Cell Line, Tumor; Cyclin D1; Dimerization; Down-Regulation; Drugs, Chinese Herbal; HCT116 Cells; HeLa Cells; Humans; Inhibitor of Apoptosis Proteins; Luciferases; Male; Microtubule-Associated Proteins; Models, Molecular; Phenanthrenes; Phosphorylation; Prostatic Neoplasms; Protein-Tyrosine Kinases; STAT3 Transcription Factor; Stomach Neoplasms; Survivin