Antiproliferative and toxicological properties of drimanes obtained from Drimys brasiliensis stem barks.

Stem barks of Drimys brasiliensis (Winteraceae) are consumed by the population in the form of a condiment. It is widely used to treat gastric and stomach problems and also to treat cancer. The extracts have demonstrated antiproliferative, antileishmanial and antimicrobial activities assigned to drimane sesquiterpenes. This study aimed to optimize the extraction conditions of the drimanes sesquiterpenes identified as 1-ß-(p-coumaroyloxy)-polygodial 1, drimanial 2 and 1-ß-(p-methoxycinnamoyl)-polygodial 3 in stem bark extracts. The HPLC-DAD method was developed and validated for the quantification of drimanes 1-3. The cytotoxic activity of these drimanes in human cancer cells, and the toxicological effects of the hydroethanolic extract, were determined. The extracts were prepared using different extractive conditions (solvents, plant: solvent ratio and time). The cytotoxicity effect was evaluated against leukemia, lymphomas, carcinomas and sarcomas cells using the tetrazolium assay (MTT). Furthermore, the acute toxicity was determined by measuring the biochemical parameters and by histopathological analysis. The hemolytic activity and micronucleus test were also performed. The method was linear, sensitive, precise and accurate for both drimanes 1-3. The best condition for extraction was using dichloromethane with plant: solvent proportion 1:10 (w/v) for six hours under dynamic maceration. Isolated drimanes exhibited cytotoxic effects with IC50 values ​​ranging from 0.13 to 112.67 µM. Compound 1 demonstrated significant results for acute promyelocytic leukemia (NB4) and Burkitt's lymphoma (RAMOS) cells while driamane 3 for Burkitt's lymphoma (RAJI) and acute T cell leukemia (MOLT4) cells. No signs of toxicity was observed and neither was mutagenicity or hemolytic activity.

Multitarget effects of quercetin in leukemia.

This study proposes to investigate quercetin antitumor efficacy in vitro and in vivo, using the P39 cell line as a model. The experimental design comprised leukemic cells or xenografts of P39 cells, treated in vitro or in vivo, respectively, with quercetin; apoptosis, cell-cycle and autophagy activation were then evaluated. Quercetin caused pronounced apoptosis in P39 leukemia cells, followed by Bcl-2, Bcl-xL, Mcl-1 downregulation, Bax upregulation, and mitochondrial translocation, triggering cytochrome c release and caspases activation. Quercetin also induced the expression of FasL protein. Furthermore, our results demonstrated an antioxidant activity of quercetin. Quercetin treatment resulted in an increased cell arrest in G1 phase of the cell cycle, with pronounced decrease in CDK2, CDK6, cyclin D, cyclin E, and cyclin A proteins, decreased Rb phosphorylation and increased p21 and p27 expression. Quercetin induced autophagosome formation in the P39 cell line. Autophagy inhibition induced by quercetin with chloroquine triggered apoptosis but did not alter quercetin modulation in the G1 phase. P39 cell treatment with a combination of quercetin and selective inhibitors of ERK1/2 and/or JNK (PD184352 or SP600125, respectively), significantly decreased cells in G1 phase, this treatment, however, did not change the apoptotic cell number. Furthermore, in vivo administration of quercetin significantly reduced tumor volume in P39 xenografts and confirmed in vitro results regarding apoptosis, autophagy, and cell-cycle arrest. The antitumor activity of quercetin both in vitro and in vivo revealed in this study, point to quercetin as an attractive antitumor agent for hematologic malignancies.

ANKHD1, a novel component of the Hippo signaling pathway, promotes YAP1 activation and cell cycle progression in prostate cancer cells.

ANKHD1 is a multiple ankyrin repeat containing protein, recently identified as a novel member of the Hippo signaling pathway. The present study aimed to investigate the role of ANKHD1 in DU145 and LNCaP prostate cancer cells. ANKHD1 and YAP1 were found to be highly expressed in prostate cancer cells, and ANKHD1 silencing decreased cell growth, delayed cell cycle progression at the S phase, and reduced tumor xenograft growth. Moreover, ANKHD1 knockdown downregulated YAP1 expression and activation, and reduced the expression of CCNA2, a YAP1 target gene. These findings indicate that ANKHD1 is a positive regulator of YAP1 and promotes cell growth and cell cycle progression through Cyclin A upregulation.

Cytoskeletal rearrangement and cell death induced by Bothrops alternatus snake venom in cultured Madin-Darby canine kidney cells.

Bothrops snake venoms cause renal damage, with renal failure being the main cause of death in humans bitten by these snakes. In this work, we investigated the cytoskeletal rearrangement and cytotoxicity caused by Bothrops alternatus venom in cultured Madin-Darby canine kidney (MDCK) cells. Incubation with venom (10 and 100 microg/mL) significantly (p <0.05) decreased the cellular uptake of neutral red dye after 1 and 3 h. Venom (100 microg/mL) also markedly decreased the transepithelial electrical resistance (RT) across MDCK monolayers. Staining with rhodamine-conjugated phalloidin revealed disarray of the cytoskeleton that involved the stress fibers at the basal cell surface and focal adhesion-associated F-actin in the cell-matrix contact region. Feulgen staining showed a significant decrease in the number of cells undergoing mitosis and an increase in the frequency of altered nuclei. Scanning electron microscopy revealed a decrease in the number of microvilli and the presence of cells with a fusiform format. Flow cytometry with annexin V and propidium iodide showed that cell death occurred by necrosis, with little apoptosis, a conclusion supported by the lack of DNA fragmentation characteristic of apoptosis. Pretreating the cells with catalase significantly attenuated the venom-induced loss of viability, indicating a possible involvement of H2O2 in the cellular damage; less protection was observed with superoxide dismutase or N omega-nitro-L-arginine methyl ester. These results indicate that Bothrops alternatus venom is cytotoxic to cultured MDCK cells, possibly via the action of reactive oxygen species. This cytotoxicity could contribute to nephrotoxicity after envenoming by this species.