Mechanisms involved in the anti-tumor effects of Toosendanin in glioma cells

Background Toosendanin (TSN) is a triterpenoid compound mainly used as an ascaris repellant. Recent studies have shown that it possesses antitumor effects in many types of tumor cells. However, the effects of TSN on glioma cells have rarely been reported. Methods Different assays were performed to investigate the effects of TSN on the different glioma cell lines including U87MG and LN18. The assays included colony formation, wound healing, and transwell assays. Furthermore, Hoechst 33342 staining, flow cytometry, and western blotting analysis were performed to investigate the apoptotic activities of TSN. Finally, the results were confirmed using a xenograft tumor model that comprised of nude mice. Results In vitro, the CCK-8 and colony formation assays showed that TSN effectively inhibited glioma cell proliferation. Moreover, the inhibitory effects on glioma cell migration and invasion were demonstrated through the wound healing and transwell assays, respectively. Hoechst 33342 staining, flow cytometry, and western blotting assays demonstrated the significant effect of TSN in the apoptosis induction of glioma cells. Furthermore, the anti-glioma effect of TSN was exerted through the inhibition of the PI3K/Akt/mTOR signaling pathways as demonstrated by western blotting analysis. In addition, the effects of TSN on glioma cell viability, apoptosis, cell cycle arrest, migration, and invasion were reversed by 740Y-P, a PI3K activator. Finally, the mouse xenograft model confirmed the suppressive effect of TSN on tumor growth in vivo. Conclusion Our results suggest that TSN is a promising chemotherapeutic drug for patients with glioma.

Neuroprotective Effects of Delta-9-Tetrahydrocannabinol against FeSO4- and H2O2-Induced Cell Damage on Dopaminergic Neurons in Primary Mesencephalic Cell Culture

Delta-9-Tetrahydrocannabinol and other phytocannabinoids have been previously demonstrated to possess neuroprotective effects in murine mesencephalic cell culture models of Parkinson’s disease, in which increased levels of superoxide radicals led to the loss of dopaminergic neurons. In these models, delta-9-tetrahydrocannabinol did not scavenge these radicals but displayed antioxidative capacity by increasing glutathione levels. Based on these findings, in the present study, we investigated whether the neuroprotective effect of delta-9-tetrahydrocannabinol can also be detected in FeSO4- and H2O2-stressed cells. Mesencephalic cultures were concomitantly treated with FeSO4 (350 μM) or H2O2 (150 μM) and delta-9-tetrahydrocannabinol (0.01, 0.1, 1, 10 μM) on the 12th days in vitro for 48 h. On the 14th DIV, dopaminergic neurons were stained immunocytochemically by tyrosine hydroxylase, and fluorescently using crystal violet, Hoechst 33342, and JC-1. FeSO4 and H2O2 significantly reduced the number of dopaminergic neurons by 33 and 36%, respectively, and adversely affected the morphology of surviving neurons. Moreover, FeSO4, but not H2O2, significantly decreased the fluorescence intensity of crystal violet and Hoechst 33342, and reduced the red/green ratio of JC-1. Co-treatment with delta-9-tetrahydrocannabinol at the concentrations 0.01 and 0.1 μM significantly rescued dopaminergic neurons in FeSO4 and H2O2-treated cultures by 16 and 30%, respectively. delta-9-Tetrahydrocannabinol treatment also led to a higher fluorescence intensity of crystal violet and Hoechst 33342, and increased the red/green fluorescence ratio of JC-1 when concomitantly administered with FeSO4 but not H2O2. To conclude, delta-9-tetrahydrocannabinol rescues dopaminergic neurons against FeSO4- and H2O2-induced neurotoxicity. Using fluorescence dyes, this effect seems to be mediated partially by restoring mitochondrial integrity and decreasing cell death, particularly in FeSO4-treated cultures.

Apoptosis assessment in high-content and high-throughput screening assays

Here the authors describe the development of AUTOptosis, an economical and rapid apoptosis monitoring method suitable for high-content and high-throughput screening assays. AUTOptosis is based on the quantification of nuclei intensity via staining with Hoechst 33342. First, the authors calibrated the method using standard apoptosis inducers in multiple cell lines. Next, the authors validated the applicability of this approach to high-content screening using a small library of compounds and compared it with the terminal deoxynucleotidyl transferase dUTP nick end labeling gold standard. Finally, the authors demonstrated the specificity of the method by using AUTOposis to detect apoptosis triggered by Mycobacterium tuberculosis intracellular infections.

Clinical significance of cancer stem cell markers in lung carcinoma

The identification of side population (SP) cells in several cancer studies has been proved to be involved in the treatment failure (chemotherapy) and tumor relapse. Here we have sorted 7% of side population (SP) cells from lung adenocarcinoma by Hoechst 33342 dye expulsion method. Further, the characterization of sorted SP cells showed cancer stem like properties such as transcriptional upregulation of stemness genes (OCT-4, SOX2 and NANOG), ATP binding cassette (ABC) transporter protein (ABCG2) and enhanced level of stem cell surface markers such as CD133 and CD44. Therefore, the aforesaid properties of lung adenocarcinoma SP cells play a significant and functional role in tumor invasion, metastasis, chemotherapeutic drug resistance and tumor recurrence in lung cancer.

Complexities of a protonatable substrate in measurements of Hoechst 33342 transport by multidrug transporter LmrP

Multidrug transporters can confer drug resistance on cells by extruding structurally unrelated compounds from the cellular interior. In transport assays, Hoechst 33342 (referred to as Hoechst) is a commonly used substrate, the fluorescence of which changes in the transport process. With three basic nitrogen atoms that can be protonated, Hoechst can exist as cationic and neutral species that have different fluorescence emissions and different abilities to diffuse across cell envelopes and interact with lipids and intracellular nucleic acids. Due to this complexity, the mechanism of Hoechst transport by multidrug transporters is poorly characterised. We investigated Hoechst transport by the bacterial major facilitator superfamily multidrug-proton antiporter LmrP in Lactococcus lactis and developed a novel assay for the direct quantitation of cell-associated Hoechst. We observe that changes in Hoechst fluorescence in cells do not always correlate with changes in the amount of Hoechst. Our data indicate that chemical proton gradient-dependent efflux by LmrP in cells converts populations of highly fluorescent, membrane-intercalated Hoechst in the alkaline interior into populations of less fluorescent, cell surface-bound Hoechst in the acidic exterior. Our methods and findings are directly relevant for the transport of many amphiphilic antibiotics, antineoplastic agents and cytotoxic compounds that are differentially protonated within the physiological pH range.

Survivin Suppression Strengthens BZML-induced Mitotic Catastrophe to Overcome Multidrug Resistance by Removing Senescent A549/Taxol Cells

Background: Mitotic catastrophe (MC) of cancer cells induced by BZML, a novel colchicine-binding site inhibitor, exerts a significant advantage in overcoming multidrug resistance (MDR) in NSCLC. However, the long cellular death process resulting from MC is not beneficial for anticancer treatment. Here, we study the mechanisms underlying MC occurrence and development to promote the development of anticancer therapies based on drug-induced MC.Methods: Cellular senescence was confirmed by morphological features, SA-β-Gal and C12FDG staining. Cell cycle analysis and Hoechst 33342 staining were used to detect MC. Relevant signal transduction pathways and protein location were detected by qRT-PCR, westren blot and immunofluorescence. The half-life of proteins was evaluated using the protein synthesis inhibitor cycloheximide. Flow cytometry, MTT assay, crystal violet staining, Hoechst 33342 staining and cell division detection were performed to determine the effects of BZML and/or YM155 on cell fate. Results: We found that BZML induced p53-dependent cellular senescence in A549/Taxol cells, but not in A549, H1299 and MDA-MB-231 cells. Interestingly, BZML-induced senescence was a secondary effect of MC. In addition, the destruction of the protein-degradation system induced by BZML contributed not only to an increase in p53 protein but also to the accumulation of survivin in the nucleus of A549/Taxol cells. However, in A549 cells, the overexpression of survivin had no effect on apoptosis resistance against BZML and failed to promote BZML-induced MC. The inhibition of survivin did not prevent MC occurrence. Unexpectedly, targeting survivin with YM155 accelerated the death of the MC cells by eliminating senescent cells and strengthening the efficiency of BZML in overcoming the MDR of A549/Taxol cells.Conclusions: Our data suggest that nuclear accumulation of survivin can delay cellular death during MC by promoting the survival of senescent BZML-treated A549/Taxol cells. Further, depending on the dose sequence, combination therapy with YM155 to inhibit survivin might be a new strategy for potentiating BZML-induced MC to overcome MDR during cancer treatment.

miR-188 promotes Oxaliplatin resistances through targeting RASA1 in colon cancer cells

Background: One main drawback of chemotherapy application in colon cancer clinically is drug resistance. miR-188-5p has been shown to be down-regulated in various types of cancer. The aim of this study was to explore the molecular mechanism of miR-188-5p in drug resistant cancer cells. Methods: we examined the effects of miR-188-5p on the sensitivity of colon cancer cells to oxaliplatin (OXA) by using SW480/OXA cell line. The target of miR-188-5p was determined by luciferase activity assay. The cell cycle distribution were detected by flow cytometry. The expression of p21, Hoechst 33342 staining and Annexin V assays were used to detect the cell apoptosis. Results: The expression of miR-188-5p was significantly increased in SW480/OXA cells compared with SW480 cells. By luciferase assay we found that miR-188-5p miRNA binds to RASA1 (Ras GTPase-activating protein 1, also known as p120RasGAP), and overexpression of miR-188-5p inhibited RASA1 expression by binding to the 3'-untranslated region of RASA1 mRNA. In addition, suppression of miR-188-5p enhanced the chemosensitivity of the oxaliplatin-resistant colon cancer cells. Furthermore, suppression of RASA1 abrogated the increasement of cell apoptosis induced by miR-188-5p inhibitor, while, overexpression of RASA1 induced cell apoptosis in SW480/OXA cells. Our results suggested that miR-188-5p played chemoresistant role in colon cancer through regulating RASA1 expression. Conclusion: The findings of our study suggest that target miR-188-5p is capable of enhancing the chemosensitivity of colon cancer cells by promoting RASA1.