cucurbitacin-i and Colonic-Neoplasms

Topics: Animals; Colonic Neoplasms; HCT116 Cells; Humans; Male; Mice; Mice, Nude; Molecular Docking Simulation; Neoplasm Proteins; Protein Domains; Receptors, Notch; Signal Transduction; Triterpenes; Xenograft Model Antitumor Assays

Colorectal cancers are the third most common types of cancers worldwide. Surgical resection is unable to eliminate tumors completely due to metastasis. A demand for new chemotherapeutic tools exists. In the present study, we examined the chemopreventive potential of cucurbitacin I, a natural component extracted from plants of the Cucurbitaceae family, in the colon cancer cell line COLO205. We hypothesized that cucurbitacin I would prevent colon cancer cell migration and invasion, and sensitize colon cancer cells to chemotherapy. Our data demonstrated that exposure of the COLO205 cells to cucurbitacin I significantly decreased cell viability. Furthermore our data demonstrated for the first time that in the COLO205 cells, cucurbitacin I could suppress the cell migration and invasion, and harbor chemosensitization activity against colon cancer. The anticancer activity of cucurbitacin I was accomplished by downregulating p-STAT3 and MMP-9 expression. Collectively, our results suggest that cucurbitacin I may be a potent adjuvant chemotherapeutic agent for colon cancer with anti-migration, anti-invasion and chemosensitizing activities.

Topics: Adenocarcinoma; Antineoplastic Agents, Phytogenic; Cell Division; Cell Line, Tumor; Cell Movement; Colonic Neoplasms; Depression, Chemical; Drug Resistance, Neoplasm; Drug Screening Assays, Antitumor; Humans; Matrix Metalloproteinase 9; Neoplasm Invasiveness; Phosphorylation; Protein Processing, Post-Translational; STAT3 Transcription Factor; Triterpenes

Cucurbitacin-I is a triterpenoids found in medicinal plants and have diverse pharmacological and biological activities. In this study, the antitumor effects of cucurbitacin-I on colon cancer and possible roles in apoptosis and cell cycle arrest were investigated. Treatment of SW480 cells, a human colon cancer cells, with cucurbitacin-I decreased cell viability and cell proliferation in a concentration-dependent manner. Also, cucurbitacin-I induced G2/M phase cell cycle arrest in SW480 cells with a decreased expression of cell cycle proteins including cyclin B1, cyclin A, CDK1, and CDC25C. Moreover, cucurbitacin-I induced increased cleavage of caspase-3, -7, -8, -9, and poly ADP ribose polymerase. When we examined the inhibitory effect of cucurbitacin-I on tumor growth in vivo, cucurbitacin-I effectively inhibited the tumorigenicity and growth of CT-26 cells in syngenic BALB/c mice. In summary, the present study showed that cucurbitacin-I reduced colon cancer cell proliferation by enhancing apoptosis and causing cell cycle arrest at the G2/M phase.

Topics: Animals; Apoptosis; Blotting, Western; Caspases; CDC2 Protein Kinase; cdc25 Phosphatases; Cell Cycle Checkpoints; Cell Line, Tumor; Cell Survival; Colonic Neoplasms; Cucurbitaceae; Cyclin A; Cyclin B1; Cyclin-Dependent Kinases; Flow Cytometry; Humans; Male; Membrane Potential, Mitochondrial; Mice; Mice, Inbred BALB C; Neoplasms, Experimental; Poly (ADP-Ribose) Polymerase-1; Poly(ADP-ribose) Polymerases; Triterpenes

Cucurbitacins have been shown to inhibit proliferation in a variety of cancer cell lines. The aim of this study was to determine their biological activity in colon cancer cell lines that do not harbor activated STAT3, the key target of cucurbitacin. In order to establish the role of activated kRas in the responsiveness of cells to cucurbitacins, we performed experiments in isogenic colon cancer cell lines, HCT116 and Hke-3, which differ only by the presence of an activated kRas allele. We compared the activity of 23, 24-dihydrocucurbitacin B (DHCB) and cucurbitacin R (CCR), two cucurbitacins that we recently isolated, with cucurbitacin I (CCI), a cucurbitacin with established antitumorigenic activity. We showed that cucurbitacins induced dramatic changes in the cytoskeleton (collapse of actin and bundling of tubulin microfilaments), inhibited proliferation and finally induced apoptosis of both HCT116 and Hke-3 cells. However, the presence of oncogenic kRas significantly decreased the sensitivity of cells to the three cucurbitacins tested, CCR, DHCB and CCI. We confirmed that mutational activation of kRas protects cells from cucurbitacin-induced apoptosis using nontransformed intestinal epithelial cells with inducible expression of kRasV12. Cucurbitacins induced the expression of p53 and p21 predominantly in HCT116 cells that harbor mutant Ras. Using HCT116 cells with targeted deletion of p53 or p21 we confirmed that p53 and p21 protect cells from apoptosis induced by cucurbitacins. These results demonstrated that sensitivity of human colon cancer cell lines to cucurbitacins depends on the kRas and p53/p21 status, and established that cucurbitacins can exert antitumorigenic activity in the absence of activated STAT3.

Topics: Antineoplastic Agents; Apoptosis; Cell Line, Tumor; Cell Proliferation; Colonic Neoplasms; Cyclin-Dependent Kinase Inhibitor p21; Humans; Proto-Oncogene Proteins; Proto-Oncogene Proteins p21(ras); ras Proteins; Triterpenes; Tumor Suppressor Protein p53

Abnormal dendritic cell differentiation and accumulation of immunosuppressive myeloid cells in cancer is one of the major factors of tumor nonresponsiveness. We have previously shown that hyperactivation of the Janus-activated kinase 2/signal transducers and activators of transcription 3 (JAK2/STAT3) induced by tumor-derived factors (TDF) is responsible for abnormal dendritic cell differentiation. Here, using a novel selective inhibitor of JAK2/STAT3 JSI-124, we investigated the possibility of pharmacologic regulation of dendritic cell differentiation in cancer. Our experiments in vitro have shown that JSI-124 overcomes the differentiation block induced by TDF and promotes the differentiation of mature dendritic cells and macrophages. JSI-124 significantly reduced the presence of immature myeloid cells in vivo and promoted accumulation of mature dendritic cells. In addition to a direct antitumor effect in several animal models, JSI-124 significantly enhanced the effect of cancer immunotherapy. This indicates that pharmacologic inhibition of the JAK2/STAT3 pathway can be an important new therapeutic strategy to enhance antitumor activity of cancer immunotherapy.

Topics: Animals; CD4-Positive T-Lymphocytes; CD8-Positive T-Lymphocytes; Cell Differentiation; Cell Line, Tumor; Colonic Neoplasms; Dendritic Cells; Epitopes, T-Lymphocyte; Female; Immunotherapy, Adoptive; Janus Kinase 2; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Mice, Transgenic; Myeloid Cells; NIH 3T3 Cells; Protein-Tyrosine Kinases; Proto-Oncogene Proteins; Sarcoma, Experimental; Signal Transduction; STAT3 Transcription Factor; Triterpenes