amooranin and Carcinoma

K-Ras activating mutations are a major problem that drives aggressive tumor growth and metastasis in pancreatic cancer. Currently, there are no effective targeted therapies for this genetically defined subset of cancers harboring oncogenic K-Ras mutations that confer drug resistance, aggressive tumor growth, metastasis and poor clinical outcome. We identified a novel synthetic oleanane triterpenoid compound designated AMR-MeOAc that effectively kills K-Ras mutant pancreatic cancer HPAF-II cells. The cytotoxic effects correlated with apoptosis induction, as was evidenced by increase of apoptosis cells upon the treatment of AMR-MeOAc in HPAF-II cells. Our studies revealed that AMR-MeOAc treatment inhibits cancer associated survival gene survivin. Moreover, AMR-MeOAc also led to down regulation of Akt, ERK1/2 and survivin protein levels. Our results indicate that AMR-MeOAc or its active analogs could be a novel class of anticancer agents against K-Ras driven human pancreatic cancer.

Topics: Antineoplastic Agents, Phytogenic; Apoptosis; Carcinoma; Cell Line, Tumor; Drug Screening Assays, Antitumor; Healthy Volunteers; Humans; Inhibitor of Apoptosis Proteins; MAP Kinase Signaling System; Meliaceae; Pancreatic Neoplasms; Proto-Oncogene Proteins c-akt; ras Proteins; Survivin; Triterpenes

Amooranin (AMR), a natural triterpenoid drug isolated and characterized from Amoora rohituka stem bark, is cytotoxic to SW620 human colon carcinoma cell line with an IC(50) value of 2.9 microg/ml. This novel compound caused depolarization of mitochondrial membrane and decrease of membrane potential, indicating initial signal of apoptosis induction. The percentage of cells with decreased mitochondrial potential ranged from 7.4% at 1 microg/ml to 60.5% at 100 microg/ml AMR. Flow cytometric analysis of apoptosis using Annexin-V-FITC staining showed that the percentage of apoptotic cells ranged from 7.5% at 1 microg/ml to 59.2% at 100 microg/ml AMR. AMR-induced apoptosis was accompanied by redistribution of cytochrome c from mitochondria to cytosol as well as down regulation of Bcl-2 and Bcl-X(L) proteins in a dose-dependent manner. SW620 human colon carcinoma xenograft mice treated with AMR showed significant reduction in tumor growth rates compared to saline- and doxorubicin-treated groups. The reduction in tumor growth rate was better in xenografts treated with 2 mg/kg AMR than 5 and 10 mg/kg treated mice. The analysis of global gene expression changes induced by AMR in xenograft tumors by microarray hybridization revealed that several genes involved in energy pathways, transport, apoptosis, immune response, nucleic acid metabolism, protein metabolism, cell growth and/or maintenance, signal transduction and cell communication, were affected by this natural cancer drug. These results suggest that the anticancer properties of AMR in SW620 human colon carcinoma cell line are mediated through its effects on functional genomics, targeting the apoptotic process.

Topics: Animals; Antineoplastic Agents; Apoptosis; bcl-X Protein; Carcinoma; Cell Line, Tumor; Colonic Neoplasms; Cytochromes c; Cytosol; Dose-Response Relationship, Drug; Down-Regulation; Flow Cytometry; Gene Expression Regulation, Neoplastic; Humans; Mice; Mice, Nude; Mitochondria; Proto-Oncogene Proteins c-bcl-2; Reverse Transcriptase Polymerase Chain Reaction; Transplantation, Heterologous; Triterpenes

Amooranin (AMR), a plant terpenoid, isolated from Amoora rohituka, was investigated for its ability to overcome multidrug resistance in human leukemia and colon carcinoma cell lines. AMR IC(50) values of multidrug-resistant leukemia (CEM/VLB) and colon carcinoma (SW620/Ad-300) cell lines were higher (1.9- and 6-fold) than parental sensitive cell lines (CEM and SW620). AMR induced G(2)+M phase-arrest during cell cycle traverse in leukemia and colon carcinoma cell lines and the percentage of cells in G(2)+M phase increased in a dose-dependent manner. Coincubation of tumor cells with both DOX and AMR reversed DOX resistance in 104-fold DOX-resistant CEM/VLB and 111-fold DOX-resistant SW620/Ad-300 cell lines with a dose modification factor of 50.9 and 99.6, respectively. Flow cytometric assay showed that AMR causes enhanced cellular DOX accumulation in a dose-dependent manner. AMR inhibits photolabeling of P-glycoprotein (P-gp) with [(3)H]-azidopine and the blocking effect enhanced with increasing concentrations of AMR. Our results show that AMR competitively inhibits P-gp-mediated DOX efflux, suggestive of a mechanism underlying the enhanced DOX accumulation and reversal of multidrug resistance by AMR.

Topics: Affinity Labels; Antineoplastic Agents, Phytogenic; ATP Binding Cassette Transporter, Subfamily B, Member 1; Azides; Carcinoma; Cell Cycle; Cell Survival; Colonic Neoplasms; Dihydropyridines; Dose-Response Relationship, Drug; Doxorubicin; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Humans; Leukemia; Triterpenes; Tumor Cells, Cultured

Amooranin (AMR) is a triterpene acid isolated from the stem bark of a tropical tree (Amoora rohituka) grown wild in India. A. rohituka stem bark is one of the components of a medicinal preparation used in the Indian Ayurvedic system of medicine for the treatment of human malignancies. We investigated the mechanism of cell death associated with AMR cytotoxicity in human mammary carcinoma MCF-7, multidrug resistant breast carcinoma MCF-7/TH and breast epithelial MCF-10A cell lines. AMR IC50 values ranged between 3.8-6.9 microg/ml among MCF-7, MCF-7/TH and MCF-10A cells. AMR induced oligonucleosome-sized DNA ladder formation characteristic of apoptosis when tumor cells were treated with 1-8 microg/ml AMR for 48 h. In situ cell death detection assay indicated that AMR caused 37.3-72.1% apoptotic cells in MCF-7, 32-48.7% in MCF-7/TH and 0-37.1% in MCF- 10A cells at 1-8 microg/ml concentrations. The induction of apoptosis in AMR treated cells was accompanied by the elevation of total caspase and caspase-8 activities. Flow cytometric analysis showed that AMR induced caspase-8 activation in 40.8-71% MCF-7, 28.5-43.2% MCF-7/TH and 4-32.8% MCF-10A cells at 1-8 microg/ml concentrations. Our results suggest that AMR is a novel drug having potential for clinical development against human malignancies.

Topics: Apoptosis; Breast Neoplasms; Carcinoma; Caspase 8; Caspase 9; Caspases; Dose-Response Relationship, Drug; Drug Resistance, Multiple; Enzyme Induction; Female; Humans; Plant Bark; Plant Extracts; Triterpenes; Tumor Cells, Cultured