Establishment and characterization of a new drug surviving cell line Am1010, derived directly from muscle metastases of a human lung adenocarcinoma patient with multi-drug-resistance tOcisplatin, taxol, and gefitinib

Aim:

To Characterize a new human lung cancer cell line Am1010, derived from drug-surviving cells (DSCs).

Methods:

The Am1010 cell line was established after 4 cycles of chemotherapy from an arm muscle metastasic tumor of a patient diagnosed with lung adenocarcinoma. The cell line has been remained in continuous culture for more than one year during this study.

Results:

The Am1010 cell line demonstrated in vitro multi-drug-resistance to cisplatin, taxol, and gefitinib. The Am1010 cell doubling time without drug treatment was 42.395 h. The IC₅₀ value of cisplatin was 4.299 μmol/L and >10 μmol/L for the Am1010 and P0318 (a cell line derived from non-DSCs) cells, respectively. The IC₅₀ value of taxol was 0.067 μmol/L and >1 μmol/L for the Am1010 and P0318 cells, respectively. The IC₅₀ value of gefitinib was 15.233 μmol/L and >70 μmol/L for Am1010 and P0318 cells, respectively. 11 genes involved in the focal adhesion and cell adhesion pathways were found to be differentially expressed. The cells of Am1010 have a significantly larger chromosome number than most lung cancer cell lines.

Conclusion:

This novel DSCs derived lung cancer cell line will be a valuable in vitro tool for the investigation of lung cancer drug resistance and metastasis.     

Protective effect of Bu-7, a flavonoid extracted from Clausena lansium, against rotenone injury in PC12 cells

Aim:

To investigate the protective effect and underlying mechanisms of Bu-7, a flavonoid isolated from the leaves of Clausena lansium, against rotenone-induced injury in PC12 cells.

Methods:

The cell viability was evaluated using MTT assay. The cell apoptosis rate was analyzed using flow cytometry. JC-1 staining was used to detect the mitochondrial membrane potential (MMP). Western blotting analysis was used to determine the phosphorylation of c-Jun N-terminal kinase (JNK), p38 mitogen-activated protein kinase (p38), tumor protein 53 (p53), Bcl-2–associated X protein (Bax), B-cell lymphoma 2 (Bcl-2), and caspase 3.

Results:

Treatment of PC12 cells with rotenone (1–20 μmol/L) significantly reduced the cell viability in a concentration-dependent manner. Pretreatment with Bu-7 (0.1 and 10 μmol/L) prevented PC12 cells from rotenone injury, whereas Bu-7 (1 μmol/L) had no significant effect. Pretreatment with Bu-7 (0.1 and 10 μmol/L) decreased rotenone-induced apoptosis, attenuated rotenone-induced mitochondrial potential reduction and suppressed rotenone-induced protein phosphorylation and expression, whereas Bu-7 (1 μmol/L) did not cause similar effects. Bu-7 showed inverted bell-shaped dose-response relationship in all the effects.

Conclusion:

Bu-7 protects PC12 cells against rotenone injury, which may be attributed to MAP kinase cascade (JNK and p38) signaling pathway. Thus, Bu-7 may be a potential bioactive compound for the treatment of Parkinson''s disease.     

Huperzine A derivative M3 protects PC12 cells against sodium nitroprusside-induced apoptosis

Aim:

To investigate the effects of M3, a derivative of huperzine A, on the apoptosis induced by sodium nitroprusside (SNP) in PC12 cells.

Methods:

Cell viability was detected using MTT method. Apoptosis was examined with annexin V/prodium iodide (PI) stain. The levels of reactive oxygen species (ROS) were measured using fluorophotometric quantitation. The amount of malonaldehyde (MDA) was determined with MDA detection kits. The expression of caspase-3 and Hsp70 were analyzed using Western blotting.

Results:

Exposure of PC12 cells to SNP (200 μmol/L) for 24 h decreased the cell viability to 69.0% of that in the control group. Pretreatment with M3 (10 μmol/L) or huperzine A (10 μmol/L) significantly protected the cells against SNP-induced injury and apoptosis; the ratio of apoptotic bodies in PC12 cells was decreased from 27.3% to 15.0%. Pretreatment with M3 (10 μmol/L) significantly decreased ROS and MDA levels, and increased the expression of Hsp70 in the cells. Quercetin (10 μmol/L) blocked the protective effect of M3, while did not influence on that of huperzine A.

Conclusion:

M3 protects PC12 cells against SNP-induced apoptosis, possible due to ROS scavenging and Hsp70 induction.     

Vam3, a resveratrol dimer,inhibits cigarette smoke- induced cell apoptosis in lungs by improving mitochondrial function

Aim： To investigate the effects of Vam3 （a resveratrol dimer extracted from Vitis amurensis Rupr） on cigarette smoke （CS）-induced cell apoptosis in lungs in vitro and in vivo and the underlying mechanisms of action.
Methods： Human bronchial epithelial cell line BEAS-2B was exposed to cigarette smoke condensate （CSC, 300 mg/L）, and cell apoptosis was determined using flow cytometry and Hoechst staining. Mitochondrial membrane potential was examined with TMRE staining. ROS and ceramide levels were detected with DCFH-DA fluorescence and HPLC-MS/MS, respectively. Cytochrome c release was detected using immunofluorescence. Caspase-9 and neutral sphingomyelinase 2 expression was measured with Western blotting. The breast carcinoma cell line MCF7 stably expressing GFP-tagged Bax was used to elucidate the role of mitochondria in CS-induced apoptosis. For in vivo study, male mice were exposed to CS for 5 min twice a day for 4 weeks. The mice were orally administered Vam3 （50 mg·kg^-1·d^-1） or resveratrol （30 mg·kg^-1·d^-1） each day 1 h before the first CS exposure.
Results： Pretreatment of BEAS-2B cells with Vam3 （5 μmol/L） or resveratrol （5 μmol/L） significantly suppressed CSC-induced apoptosis, and prevented CSC-induced Bax level increase in the mitochondria, mitochondrial membrane potential loss, cytochrome c release and caspase-9 activation. Furthermore, pretreatment of BEAS-2B cells with Vam3 or resveratrol significantly suppressed CSC-stimulated intracellular ceramide production, and CSC-induced upregulation of neutral sphingomyelinase 2, the enzyme responsible for ceramide production in bronchial epithelial cells. Similar results were obtained in C6-pyridinium ceramide-induced apoptosis of GFP-Bax-stable MCF7 cells in vitro, and in the lungs of CS-exposed mice that were treated with oral administration of Vam3 or resveratrol.
Conclusion： Vam3 protects bronchial epithelial cells from CS-induced apoptosis in vitro and in vivo by preventing mitochondrial dysfunction.     

Cyclic bisbibenzyls induce growth arrest and apoptosis of human prostate cancer PC3 cells

Aim:

To investigate the cytotoxic effects of four cyclic bisbibenzyls, Riccardin C (Ric), Pakyonol (Pak), Marchantin M (Mar), and Plagiochin E (Pla) against chemoresistant prostate cancer PC3 cells.

Methods:

Cell growth was assayed by MTT method, and apoptotic related protein Bcl-2 and Bax, poly(ADP-ribose) polymerase (PARP) were examined by Western blotting. Cell cycle and apoptosis of PC3 cells were evaluated with flow cytometry and morphologic examinations.

Results:

The four compounds inhibited proliferation and elicited cell death in a dose- and time-dependent manner with IC₅₀ values of 3.22 μmol/L for Ric, 7.98 μmol/L for Pak, 5.45 μmol/L for Mar, and 5.99 μmol/L for Pla, respectively. Furthermore, exposed to these chemicals caused a decrease in the antiapoptotic protein Bcl-2 and an increase in proapoptotic Bax expression. PARP cleavage and caspase-3 activity were also observed.

Conclusion:

The results suggest that cyclic bisbibenzyls could be used for the development of novel therapeutic chemicals against prostate cancer.     

α-Tocopheryl succinate induces apoptosis in erbB2-expressing breast cancer cell via NF-κB pathway

Aim:

To study the molecular mechanisms underlying α-tocopheryl succinate (α-TOS)-induced apoptosis in erbB2-positive breast cancer cells and to determine whether α-TOS and the human recombinant TNF-related apoptosis-inducing ligand (hrTRAIL) act synergically to induce cell death of erbB2-expressing breast cancer cells.

Methods:

The annexin V binding method was used to measure apoptosis induced by α-TOS and/or hrTRAIL. RT-PCR and Western blotting were performed to detect gene and protein expression. A colorimetric assay was performed to detect caspase activity. The TransAM^TM NF-κB p65 kit was used to assess NF-κB activation.

Results:

α-TOS (100 μmol/L) significantly inhibited NF-κB nuclear translocation in erbB2-expressing breast cancer cells; this inhibition is expected to result in the inactivation of NF-κB. α-TOS (50 and 100 μmol/L) inhibited the expression of Flice-like inhibitory protein (FLIP) and cellular inhibitor of apoptosis protein 1 (c-IAP1) in erbB2-positive cells. α-TOS (100 μmol/L) inhibited Akt activation and augmented the activity of caspase 3 and caspase 8 in breast cancer cells expressing erbB2. α-TOS (50 μmol/L) and hrTRAIL (30 mg/mL) acted synergically to induce apoptosis in breast cancer cells. α-TOS also decreased the hrTRAIL-induced transient activation of NF-κB .

Conclusion:

Our results suggest that α-TOS mediates the apoptosis of erbB2-positive breast cancer cells and acts synergically with hrTRAIL via the NF-κB pathway.     

Apoptosis induced by genipin in human leukemia K562 cells: involvement of c-Jun N-terminal kinase in G₂/M arrest

Aim:

To investigate the effect of genipin on apoptosis in human leukemia K562 cells in vitro and elucidate the underlying mechanisms.

Methods:

The effect of genipin on K562 cell viability was measured using trypan blue dye exclusion and cell counting. Morphological changes were detected using phase-contrast microscopy. Apoptosis was analyzed using DNA ladder, propidium iodide (PI)-labeled flow cytometry (FCM) and Hoechst 33258 staining. The influence of genipin on cell cycle distribution was determined using PI staining. Caspase 3 activity was analyzed to detect apoptosis at different time points. Protein levels of phospho-c-Jun, phosphor-c-Jun N-terminal kinase (p-JNK), phosphor-p38, Fas-L, p63, and Bax and the release of cytochrome c were detected using Western blot analysis.

Results:

Genipin reduced the viability of K562 cells with an IC₅₀ value of approximately 250 μmol/L. Genipin 200–400 μmol/L induced formation of typical apoptotic bodies and DNA fragmentation. Additionally, genipin 400 μmol/L significantly increased the caspase 3 activity from 8–24 h and arrested the cells in the G₂/M phase. After stimulation with genipin 500 μmol/L, the levels of p-JNK, p-c-Jun, Fas-L, Bax, and cytochrome c were remarkably upregulated, but there were no obvious changes of p-p38. Genipin 200–500 μmol/L significantly upregulated the Fas-L expression and downregulated p63 expression. Dicoumarol 100 μmol/L, a JNK1/2 inhibitor, markedly suppressed the formation of apoptotic bodies and JNK activation induced by genipin 400 μmol/L.

Conclusion:

These results suggest that genipin inhibits the proliferation of K562 cells and induces apoptosis through the activation of JNK and induction of the Fas ligand.     

Plumbagin inhibits cell growth and potentiates apoptosis in human gastric cancer cells in vitro through the NF-κB signaling pathway

Aim:

To investigate the effects and underlying mechanisms of plumbagin, a naphthoquinone derived from medicinal plant Plumbago zeylanica, on human gastric cancer (GC) cells.

Methods:

Human gastric cancer cell lines SGC-7901, MKN-28, and AGS were used. The cell viability was examined using CCK-8 viability assay. Cell proliferation rate was determined using both clonogenic assay and EdU incorporation assay. Apoptosis was detected via Annexin V/propidium iodide double-labeled flow cytometry. Western blotting was used to assess the expression of both NF-κB-regulated gene products and TNF-α-induced activation of p65, IκBα, and IKK. The intracellular location of NF-κB p65 was detected using confocal microscopy.

Results:

Plumbagin (2.5–40 μmol/L) concentration-dependently reduced the viability of the GC cells. The IC₅₀ value of plumbagin in SGC-7901, MKN-28, and AGS cells was 19.12, 13.64, and 10.12 μmol/L, respectively. The compound (5–20 μmol/L) concentration-dependently induced apoptosis of SGC-7901 cells, and potentiated the sensitivity of SGC-7901 cells to chemotherapeutic agents TNF-αand cisplatin. The compound (10 μmol/L) downregulated the expression of NF-κB-regulated gene products, including IAP1, XIAP, Bcl-2, Bcl-xL, tumor factor (TF), and VEGF. In addition to inhibition of NF-κB p65 nuclear translocation, the compound also suppressed TNF-α-induced phosphorylation of p65 and IKK, and the degradation of IκBα.

Conclusion:

Plumbagin inhibits cell growth and potentiates apoptosis in human GC cells through the NF-κB pathway.     

Icaritin suppresses the proliferation of human osteosarcoma cells in vitro by increasing apoptosis and decreasing MMP expression

Aim： To explore whether icaritin, a prenylflavonoid derivative of the Chinese tonic herb Epimedium, could suppress the proliferation of human osteosarcoma cells in vitro, and to elucidate the mechanisms of the action.
Methods： Human osteosarcoma SaOS2 cell line was used in the present study. The proliferation of the cells was examined using MTT assay and immunofluorescence DAPI staining. Cell motility was studied with the scratch assay. Cell apoptosis was determined by Annexin V-FITC and PI double staining using flow cytometry. Western blotting and RT-PCR were used to measure the expression of mRNAs and proteins in the cells.

Results： Icaritin （5–15 μmol/L） suppressed the proliferation of SaOS2 cells in vitro in a dose-dependent manner. Furthermore, the cell motility was significantly decreased after exposure to icaritin. Moreover, icaritin （5 μmol/L） time-dependently induced the apoptosis of SaOS2 cells, markedly suppressed MMP-2 and MMP-9 expression, upregulated caspase-3 and caspase-9 expression, and increased the level of cleaved caspase-3 in the cells. Co-exposure to the caspase-3 inhibitor zVAD-fmk （10 μmol/L） compromised the icaritin-induced caspase-3 expression and apoptosis in SaOS2 cells.

Conclusion： Icaritin suppresses the proliferation of SaOS2 human osteosarcoma cells by increasing apoptosis and downregulating MMP expression.     

Glucagon-like peptide 1 receptor plays a critical role in geniposide-regulated insulin secretion in INS-1 cells

Aim:

To explore the role of the glucagon-like peptide 1 receptor (GLP-1R) in geniposide regulated insulin secretion in rat INS-1 insulinoma cells.

Methods:

Rat INS-1 insulinoma cells were cultured. The content of insulin in the culture medium was measured with ELISA assay. GLP-1R gene in INS-1 cells was knocked down with shRNA interference. The level of GLP-1R protein in INS-1 cells was measured with Western blotting.

Results:

Geniposide (0.01–100 μmol/L) increased insulin secretion from INS-1 cells in a concentration-dependent manner. Geniposide (10 μmol/L) enhanced acute insulin secretion in response to both the low (5.5 mmol/L) and moderately high levels (11 mmol/L) of glucose. Blockade of GLP-1R with the GLP-1R antagonist exendin (9–39) (200 nmol/L) or knock-down of GLP-1R with shRNA interference in INS-1 cells decreased the effect of geniposide (10 μmol/L) on insulin secretion stimulated by glucose (5.5 mmol/L).

Conclusion:

Geniposide increases insulin secretion through glucagon-like peptide 1 receptors in rat INS-1 insulinoma cells.     

Crocetin induces cytotoxicity and enhances vincristine-induced cancer cell death via p53-dependent and -independent mechanisms

Aim:

To investigate the anticancer effect of crocetin, a major ingredient in saffron, and its underlying mechanisms.

Methods:

Cervical cancer cell line HeLa, non-small cell lung cancer cell line A549 and ovarian cancer cell line SKOV3 were treated with crocetin alone or in combination with vincristine. Cell proliferation was examined using MTT assay. Cell cycle distribution and sub-G₁ fraction were analyzed using flow cytometric analysis after propidium iodide staining. Apoptosis was detected using the Annexin V-FITC Apoptosis Detection Kit with flow cytometry. Cell death was measured based on the release of lactate dehydrogenase (LDH). The expression levels of p53 and p21^WAF1/Cip1 as well as caspase activation were examined using Western blot analysis.

Results:

Treatment of the 3 types of cancer cells with crocetin (60-240 μmol/L) for 48 h significantly inhibited their proliferation in a concentration-dependent manner. Crocetin (240 μmol/L) significantly induced cell cycle arrest through p53-dependent and -independent mechanisms accompanied with p21^WAF1/Cip1 induction. Crocetin (120-240 μmol/L) caused cytotoxicity in the 3 types of cancer cells by enhancing apoptosis in a time-dependent manner. In the 3 types of cancer cells, crocetin (60 μmol/L) significantly enhanced the cytotoxicity induced by vincristine (1 μmol/L). Furthermore, this synergistic effect was also detected in the vincristine-resistant breast cancer cell line MCF-7/VCR.

Conclusion:

Ccrocetin is a potential anticancer agent, which may be used as a chemotherapeutic drug or as a chemosensitizer for vincristine.     

Autophagy counteracts apoptosis in human multiple myeloma cells exposed to oridonin in vitro via regulating intracellular ROS and SIRT1

Aim:

To explore the mechanisms underlying the oridonin-induced apoptosis and autophagy in human multiple myeloma cells in vitro.

Methods:

Human multiple myeloma RPMI8266 cells were used. The cell viability was assessed using MTT assay. Morphological changes of apoptosis and autophagy were observed under transmission electron microscope. TUNEL and annexin V-FITC/PI dual staining assays were used to measure apoptosis. Autophagy was analyzed using Western blot analysis and immunofluorescence staining with a QDs_605 nm-Anti-LC3 fluorescent probe. Intracellular ROS was estimated with flow cytometry using DCFH-DA fluorescent probe. Protein levels of active caspase 3, Beclin 1 and SIRT1 were determined with Western blot analysis.

Results:

Exposure to oridonin (1-64 μmol/L) inhibited the proliferation of RPMI8266 cells in a concentration-dependent manner with an IC₅₀ value of 6.74 μmol/L. Exposure to oridonin (7 μmol/L) simultaneously induced caspase 3-mediated apoptosis and Beclin 1-dependent autophagy of RPMI8266 cells. Both the apoptosis and autophagy were time-dependent, and apoptosis was the main effector pathway of cell death. Exposure to oridonin (7 μmol/L) increased intracellular ROS and reduced SIRT1 nuclear protein in a time-dependent manner. The blockade of intracellular generation of ROS by NAC (5 mmol/L) abrogated apoptosis, autophagy and the decrease of SIRT1 in the cells exposed to oridonin (7 μmol/L). The inhibition of autophagy by 3-MA (5 mmol/L) sensitized the cells to oridonin-induced apoptosis, which was accompanied by increased intracellular ROS and decreased SIRT1.

Conclusion:

Oridonin simultaneously induces apoptosis and autophagy of human multiple myeloma RPMI8266 cells via regulation of intracellular ROS generation and SIRT1 nuclear protein. The cytotoxicity of oridonin is mainly mediated through the apoptotic pathway, whereas the autophagy protects the cells from apoptosis.     

Magnesium lithospermate B extracted from Salvia miltiorrhiza elevats intracellular Ca2＋ level in SHSY5Y cells

Aim:

To examine if magnesium lithospermate B (MLB), a potent inhibitor of Na⁺/K⁺-ATPase, leads to the elevation of intracellular Ca²⁺ level as observed in cells treated with cardiac glycosides.

Methods:

Viability of SH-SY5Y neuroblastoma cells treated with various concentrations of ouabain or MLB was measured. Intracellular Ca²⁺ levels were visualized using Fluo4-AM (fluorescent dye) when cells were treated with ouabain or MLB in the presence or absence of KB-R7943 (Na⁺/Ca²⁺ exchanger inhibitor) and 2-APB (IP₃ receptor antagonist). Molecular modeling was conducted for the docking of ouabain or MLB to Na⁺/K⁺-ATPase. Changes of cell body and dendrite morphology were monitored under a microscope.

Results:

severe toxicity was observed in cells treated with ouabain of concentration higher than 1 μmol/L for 24 h while no apparent toxicity was observed in those treated with MLB. Intracellular Ca²⁺ levels were substantially elevated by MLB (1 μmol/L) and ouabain (1 μmol/L) in similar patterns, and significantly reduced in the presence of KB-R7943 (10 μmol/L) or 2-APB (100 μmol/L). Equivalent interaction with the binding cavity of Na⁺/K⁺-ATPase was simulated for ouabain and MLB by forming five hydrogen bonds, respectively. Treatment of ouabain (1 μmol/L), but not MLB (1 μmol/L), induced dendritic shrink of SH-SY5Y cells.

Conclusion:

Comparable to ouabain, MLB leads to the elevation of intracellular Ca²⁺ level presumably via the same mechanism by inhibiting Na⁺/K⁺-ATPase. The elevated Ca²⁺ levels seem to be supplied by Ca²⁺ influx through the reversed mode of the Na⁺/Ca²⁺ exchanger and intracellular release from endoplasmic reticulum.     

Novel neuroprotectant chiral 3-n-butylphthalide inhibits tandem-pore-domain potassium channel TREK-1

Aim:

To study the effects of 3-n-butylphthalide (NBP) on the TREK-1 channel expressed in Chinese hamster ovary (CHO) cells.

Methods:

Whole-cell patch-clamp recording was used to record TREK-1 channel currents. The effects of varying doses of l-NBP on TREK-1 currents were also observed. Current-clamp recordings were performed to measure the resting membrane potential in TREK-1-transfected CHO (TREK-1/CHO) and wild-type CHO (Wt/CHO) cells.

Results:

l-NBP (0.01–10 μmol/L) showed concentration-dependent inhibition on TREK-1 currents (IC₅₀=0.06±0.03 μmol/L), with a maximum current reduction of 70% at a concentration of 10 μmol/L. l-NBP showed a more potent inhibition on TREK-1 current than d-NBP or dl-NBP. This effect was partially reversed upon washout and was not voltage-dependent. l-NBP 10 μmol/L elevated the membrane potential in TREK-1/CHO cells from -55.3 mV to -42.9 mV. However, it had no effect on the membrane potential of Wt/CHO cells.

Conclusion:

l-NBP potently inhibited TREK-1 current and elevated the membrane potential, which may contribute to its neuroprotective activity.     

Isothiafludine,a novel non-nucleoside compound,inhibits hepatitis B virus replication through blocking pregenomic RNA encapsidation

Aim： To investigate the action of isothiafludine （NZ-4）, a derivative of bis-heterocycle tandem pairs from the natural product leucamide A, on the replication cycle of hepatitis B virus （HBV） in vitro and in vivo. Methods： HBV replication cycle was monitored in HepG2.2.15 cells using qPCR, qRT-PCR, and Southern and Northern blotting. HBV protein expression and capsid assembly were detected using Western blotting and native agarose gel electrophoresis analysis. The interaction of pregenomic RNA （pgRNA） and the core protein was investigated by RNA immunoprecipitation. To evaluate the anti-HBV effect of NZ-4 in vivo, DHBV-infected ducks were orally administered NZ-4 （25, 50 or 100 mg.k~l{1-1） for 15 d. Results： NZ-4 suppressed intracellular HBV replication in HepG2.2.15 cells with an IC~o value of 1.33 pmol/L, whereas the compound inhibited the cell viability with an IC5o value of 50.4 pmol/L. Furthermore, NZ-4 was active against the replication of various drug- resistant HBV mutants, including 3TC/ETV-dual-resistant and ADV-resistant HBV mutants. NZ-4 （5, 10, and 20 pmol/L） concentration- dependently reduced the encapsidated HBV pgRNA, resulting in the assembly of replication-deficient capsids in HepG2.2.15 cells. Oral administration of NZ-4 dose-dependently inhibited DHBV DNA replication in the DHBV-infected ducks. Conclusion： NZ-4 inhibits HBV replication by interfering with the interaction between pgRNA and HBcAg in the capsid assembly process thus increasing the replication-deficient HBV capsids. Such mechanism of action might provide a new therapeutic strategy to combat H BV infection.     

Wogonin ameliorates lipotoxicity-induced apoptosis of cultured vascular smooth muscle cells via interfering with DAG-PKC pathway

Aim:

To investigate the effects of wogonin (5,7-dihydroxy-8-methoxyflavone) extracted from Scutellaria baicalensis Georgi (S baicalensis) on lipotoxicity-induced apoptosis of vascular smooth muscle cells (VSMCs) and the underlying mechanisms.

Methods:

Cultured VSMCs were used. Apoptosis of VSMCs was induced by palmitate (0.75 mmol/L), and detected using TUNEL assay. The expression levels of protein and phosphorylated protein were measured using Western blot analysis.

Results:

Treatment of VSMCs with wogonin (10, 25 and 50 μmol/L) significantly attenuated the apoptosis and endoplasmic reticulum (ER) stress induced by palmitate in concentration- and time-dependent manners. Wogonin (50 μmol/L) decreased palmitate-induced reactive oxygen species (ROS) generation. The ER stress inhibitor 4-phenyl butyric acid (5 mmol/L) significantly decreased palmitate-induced apoptotic cells, and occluded the anti-apoptotic effect of wogonin (25 μmol/L). Wogonin (10, 25 and 50 μmol/L) significantly reduced the intracellular diacylglycerol (DAG) accumulation and expression levels of phosphorylated PKCs in palmitate-treated VSMCs.

Conclusion:

Our results suggest that wogonin inhibits lipotoxicity-induced apoptosis of VSMCs via suppressing the intracellular DAG accumulation and subsequent inhibition of PKC phosphorylation. Wogonin has therapeutic potential for the prevention and treatment of atherosclerosis.     

Inhibition of the STAT3 signaling pathway is involved in the antitumor activity of cepharanthine in SaOS2 cells

Aim:

To investigate the molecular mechanisms underlying the antitumor activity of cepharanthine (CEP), an alkaloid extracted from Stephania cepharantha Hayata.

Methods:

Human osteosarcoma cell line SaOS2 was used. MTT assay, Hoechst 33342 nuclear staining, flow cytometry, Western blotting and nude mouse xenografts of SaOS2 cells were applied to examine the antitumor activity of CEP in vitro and in vivo. The expression levels of STAT3 and its downstream signaling molecules were measured with Western blotting and immunochemistry analysis. The activity of STAT3 was detected based on the phosphorylation level of STAT3, luciferase gene reporter assay and translocation of STAT3 to the nucleus.

Results:

Treatment of SaOS2 cells with CEP (2.5–20 μmol/L) inhibited the cell growth in a concentration- and time-dependent manner. CEP (10 μmol/L) caused cell cycle arrest at G₁ phase and induced apoptosis of SaOS2 cells. CEP (10 and 15 μmol/L) significantly decreased the expression of STAT3 in SaOS2 cells. Furthermore, CEP (5 and 10 μmol/L) significantly inhibited the expression of target genes of STAT3, including the anti-apoptotic gene Bcl-xL and the cell cycle regulators c-Myc and cyclin D1. In nude mouse xenografts of SaOS2 cells, CEP (20 mg·kg⁻¹·d⁻¹, ip for 19 d) significantly reduced the volume and weight of the tumor.

Conclusion:

Our findings suggest that inhibition of STAT3 signaling pathway is involved in the anti-tumor activity of CEP.     

Involvement of Bcl-2, Src, and ERα in gossypol-mediated growth inhibition and apoptosis in human uterine leiomyoma and myometrial cells

Aim:

To investigate the effect of gossypol on the growth of cultured human uterine leiomyoma and myometrial cells, the level of Bcl-2 and the activity of Src and estrogen receptor (ERα).

Methods:

Human uterine leiomyoma and adjacent normal myometrial cells were cultured in vitro. Both cell types were treated with a graded concentration of gossypol. Cell viability was assayed using CCK-8. Morphological change was observed with optical and electronic microscopy. Apoptosis was evaluated using TUNEL assay. Levels of Bcl-2, ERα and Src were analyzed using Western blotting.

Results:

Gossypol significantly inhibited growth and promoted apoptosis in cultured human uterine leiomyoma cells with the IC₅₀ value and its corresponding 95% confidence intervals (CI) of 6.5 (4.0–10.5), 9.0 (4.9–16.5), and 7.5 (4.0–14.1) μmol/L at 20, 40, and 60 h, respectively. Gossypol exerted inhibitory effects on the myometrial cells with the IC₅₀ value and its 95% CI of 49.1 (28.3–85.0), 14.5 (7.7–27.4), and 2.6 (1.2–5.6) μmol/L at 20, 40, and 60 h, respectively. Compared with control, gossypol 0.1-3.0 μmol/L markedly decreased the protein expression of Bcl-2 (P<0.05) in both leiomyoma and myometrial cells in a concentration-dependent manner, and significantly suppressed the level of phospho-Tyr416Src (P<0.05) in both cell types at 3.0 μmol/L without obvious alteration of c-Src and phospho-Tyr527Src levels (P>0.05). In addition, gossypol markedly reduced both the expression of ERα (P<0.05) at the low concentration of 0.1 μmol/L in the myometrial cells and the level of phospho-ser167ERα (P<0.05) at the high concentration of 3.0 μmol/L in the leiomyoma cells.

Conclusion:

Gossypol inhibits proliferation and induces apoptosis in human uterine leiomyoma and myometrial cells. It is likely that the mechanisms of action involve reducing the protein level of Bcl-2 and the activity of Src and ERα.