Negative regulation of mTOR activity by LKB1-AMPK signaling in non-small cell lung cancer cells

Aim:

To investigate the role of LKB1 in regulation of mTOR signaling in non-small cell lung cancer (NSCLC) cells.

Methods:

LKB1 protein expression and phosphorylation of AMPK, 4E-BP1 and S6K in the cells were assessed using Western blotting in various NSCLC cell lines (A549, H460, H1792, Calu-1 and H1299). Energy stress was mimicked by treating the cells with 2-deoxyglucose (2-DG). Compound C was used to inhibit AMPK activity. Cell growth was measured using the MTS assay.

Results:

LKB1 protein was expressed in LKB1 wild-type Calu-1, H1299 and H1792 cells, but it was undetected in LKB1 mutant A549 and H460 cells. Treatment of the LKB1 wild-type cells with 2-DG (5, 10 and 25 mmol/L) augmented the phosphorylation of AMPK in dose- and time-dependent manners. In the LKB1 wild-type cells, 2-DG dramatically suppressed the phosphorylation of two mTOR targets, 4E-BP1 and S6K, whereas the LKB1 mutant A549 and H460 cells were highly resistant to 2-DG-induced inhibition on mTOR activity. In addition, stable knockdown of LKB1 in H1299 cells impaired 2-DG-induced inhibition on mTOR activity. Pretreatment of H1299 and H1792 cells with the AMPK inhibitor compound C (10 μmol/L) blocked 2-DG-induced inhibition on mTOR activity. 2-DG inhibited the growth of H1299 cells more effectively than that of H460 cells; stable knockdown of LKB1 in H1299 cells attenuated the growth inhibition caused by 2-DG.

Conclusion:

In non-small cell lung cancer cells, LKB1/AMPK signaling negatively regulates mTOR activity and contributes to cell growth inhibition in response to energy stress.     

Resveratrol analogue 3,4,4′-trihydroxy-trans-stilbene induces apoptosis and autophagy in human non-small-cell lung cancer cells in vitro

Aim:

To investigate the effects of 3,4,4′-trihydroxy-trans-stilbene (3,4,4′-THS), an analogue of resveratrol, on human non-small-cell lung cancer (NSCLC) cells in vitro.

Methods:

Cell viability of NSCLC A549 cells was determined by MTT assay. Cell apoptosis was evaluated using flow cytometry and TUNEL assay. Cell necrosis was evaluated with LDH assay. The expression of apoptosis- or autophagy-associated proteins was measured using Western blotting. The formation of acidic compartments was detected using AO staining, neutral red staining and Lysotracker-Red staining. LC3 punctae were analyzed with fluorescence microscopy.

Results:

Treatment with 3,4,4′-THS (10-80 μmol/L) concentration-dependently inhibited the cell viability. It did not cause cell necrosis, but induced apoptosis accompanied by up-regulation of cleavaged PARP, caspase3/9 and Bax, and by down-regulation of Bcl-2 and surviving. It also increased the formation of acidic compartments, LC3-II accumulation and GFP-LC3 labeled autophagosomes in the cells. It inhibited the mTOR-dependent pathway, but did not impair autophagic flux. 3,4,4′-THS-induced cell death was enhanced by the autophagy inhibitors 3-MA (5 mmol/L) or Wortmannin (2 μmol/L). Moreover, 3,4,4′-THS treatment elevated the ROS levels in the cells, and co-treatment with 3-MA further elevated the ROS levels. 3,4,4′-THS-induced apoptosis and autophagy in the cells was attenuated by NAC (10 mmol/L)

Conclusion:

3,4,4′-THS induces both apoptosis and autophagy in NSCLC A549 cells in vitro. Autophagy inhibitors promote 3,4,4′-THS-induced apoptosis of A549 cells, thus combination of 3,4,4′-THS and autophagy inhibitor provides a promising strategy for NSCLC treatment.     

In vitro and in vivo anti-tumour effects of MPT0B014, a novel derivative aroylquinoline,and in combination with erlotinib in human non-small-cell lung cancer cells

BACKGROUND AND PURPOSE

The purpose of the current study was to assess a novel anti-cancer drug, MPT0B014, which is not a substrate for the P-glycoprotein (P-gp) transporter, alone and in combination with erlotinib, against human non-small cell lung cancer (NSCLC).

EXPERIMENTAL APPROACH

Cytotoxicity in human NSCLC cell lines was assessed by sulforhodamine B and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays. Cell cycle phase distributions were estimated with FACScan flow cytometry. Protein expression was detected by Western blotting analysis. Efflux of rhodamine 123 or calcein-acetoxymethylester was used to study the P-gp profile. The A549 xenograft model in mice was used to assess in vivo anti-tumour activity.

KEY RESULTS

MPT0B014 showed potent anti-proliferative activity against A549, H1299 and H226 cells. It induced G2/M arrest with down-regulation of Cdc (Tyr15) and Cdc25C, and up-regulation of cyclin B1, phospho-Cdc2 (Thr161) and Aurora A/B. P-gp-overexpressing National Cancer Institute/Adriamycin-Resistant cells were also sensitive to B014. B014-induced loss of Mcl-1 was accompanied by activation of caspases-3, -7, -8 and -9, and initiation of apoptosis. B014 in combination with erlotinib caused significant tumour inhibition in vitro and in vivo.

CONCLUSIONS AND IMPLICATIONS

MPT0B014 exerted cytotoxicity against human NSCLC cell lines with little susceptibility to P-gp. Combined with the EGF receptor inhibitor, erlotinib, MPT0B014 exerted significant growth inhibition of A549 cells both in vitro and in vivo. B014 could be useful as an anti-cancer agent.     

LKB1 gene inactivation does not sensitize non-small cell lung cancer cells to mTOR inhibitors in vitro

Aim:

Previous study has shown that endometrial cancers with LKB1 inactivation are highly responsive to mTOR inhibitors. In this study we examined the effect of LKB1 gene status on mTOR inhibitor responses in non-small cell lung cancer (NSCLC) cells.

Methods:

Lung cancer cell lines Calu-1, H460, H1299, H1792, and A549 were treated with the mTOR inhibitors rapamycin or everolimus (RAD001). The mTOR activity was evaluated by measuring the phosphorylation of 4EBP1 and S6K, the two primary mTOR substrates. Cells proliferation was measured by MTS or sulforhodamine B assays.

Results:

The basal level of mTOR activity in LKB1 mutant A549 and H460 cells was significantly higher than that in LKB1 wild-type Calu-1 and H1792 cells. However, the LKB1 mutant A549 and H460 cells were not more sensitive to the mTOR inhibitors than the LKB1 wild-type Calu-1 and H1792 cells. Moreover, knockdown of LKB1 gene in H1299 cells did not increase the sensitivity to the mTOR inhibitors. Treatment with rapamycin or RAD001 significantly increased the phosphorylation of AKT in both LKB1 wild-type and LKB1 mutant NSCLC cells, which was attenuated by the PI3K inhibitor {"type":"entrez-nucleotide","attrs":{"text":"LY294002","term_id":"1257998346","term_text":"LY294002"}}LY294002. Furthermore, RAD001 combined with {"type":"entrez-nucleotide","attrs":{"text":"LY294002","term_id":"1257998346","term_text":"LY294002"}}LY294002 markedly enhanced the growth inhibition on LKB1 wild-type H1792 cells and LKB1 mutant A549 cells.

Conclusion:

LKB1 gene inactivation in NSCLC cells does not increase the sensitivity to the mTOR inhibitors. The negative feedback activation of AKT by mTOR inhibition may contribute to the resistance of NSCLC cells to mTOR inhibitors.     

Resveratrol induces apoptosis of human chronic myelogenous leukemia cells in vitro through p38 and JNK-regulated H2AX phosphorylation

Aim:

The phosphorylation of histone H2AX, a novel tumor suppressor protein, is involved in regulation of cancer cell apoptosis. The aim of this study was to examine whether H2AX phosphorylation was required for resveratrol-induced apoptosis of human chronic myelogenous leukemia (CML) cells in vitro.

Methods:

K562 cells were tested. Cell apoptosis was analyzed using flow cytometry, and the phosphorylation of H2AX and other signaling proteins was examined with Western blotting. To analyze the signaling pathways, the cells were transfected with lentiviral vectors encoding H2AX-wt or specific siRNAs.

Results:

Treatment of K562 cells with resveratrol (20–100 μmol/L) induced apoptosis and phosphorylation of H2AX at Ser139 in time- and dose-dependent manners, but reduced phosphorylation of histone H3 at Ser10. Resveratrol treatment activated two MAPK family members p38 and JNK, and blocked the activation of another MAPK family member ERK. Pretreatment with the p38 inhibitor SB202190 or the JNK inhibitor SP600125 dose-dependently reduced resveratrol-induced phosphorylation of H2AX, which were also observed when the cells were transfected with p38- or JNK-specific siRNAs. Overexpression of H2AX in K562 cells markedly increased resveratrol-induced apoptosis, whereas overexpression of H2AX-139m (Ser139 was mutated to block phosphorylation) inhibited resveratrol-induced apoptosis. K562 cells transfected with H2AX-specific siRNAs were resistant to resveratrol-induced apoptosis.

Conclusion:

H2AX phosphorylation at Ser139 in human CML cells, which is regulated by p38 and JNK, is essential for resveratrol-induced apoptosis.     

Quercetin sensitizes human glioblastoma cells to temozolomide in vitro via inhibition of Hsp27

Aim： Quercetin is an effective Hsp27 inhibitor and has been reported to facilitate tumor cell apoptosis. The aim of this study was to investigate whether quercetin could sensitize human glioblastoma cells to temozolomide （TMZ） in vitro.
Methods： Both U251 and U87 human glioblastoma cells were treated with quercetin and/or TMZ for 48 h. Cell viability was detected using the MTT assay. Cell apoptosis was analyzed with caspase-3 activity kits and flow cytometry. Hsp27 expression and phosphorylation were examined using Western blot analysis. RNA interference using Hsp27 siRNA oligos was performed to knock down the gene expression of Hsp27.
Results： TMZ （200 or 400 μmol/L） alone effectively inhibited the viability of U251 and U87 cells. When combined with quercetin （30 μmol/L）, TMZ （100 μmol/L） significantly inhibited the cell viability, and the inhibition of TMZ （200 and 400 μmol/L） was enhanced. TMZ or quercetin anole did not affect caspase-3 activity and cell apoptosis, while TMZ combined with quercetin significantly increased caspase-3 activity and induced cell apoptosis. TMZ anole significantly increased Hsp27 phosphorylation in U251 and U87 cells, while quercetin or Hsp27 siRNA oligos combined with TMZ attenuated TMZ-induced Hsp27 phosphorylation and significantly inhibited Hsp27 expression.
Conclusion： Combined treatment with TMZ and quercetin efficiently suppressed human glioblastoma cell survival in vitro.     

Luteolin is effective in the non-small cell lung cancer model with L858R/T790M EGF receptor mutation and erlotinib resistance

Background and Purpose

Non-small cell lung cancer (NSCLC) is one of the most commonly diagnosed malignancies in the world. Small-molecule inhibitors of the EGF receptor''s tyrosine kinase domain (TKIs), including gefitinib and erlotinib, have been widely used for treating NSCLC. Unfortunately, nearly all patients after initially experiencing a marked improvement while on these drugs, eventually progress to acquire resistance to TKIs. Because there is no effective therapeutic strategy to treat TKI-resistant NSCLC, we evaluated the effects of luteolin, a naturally occurring flavanoid, on T790M mutant NSCLC cells.

Experimental Approach

The effect of luteolin on the viability of NSCLC and normal cell lines was investigated using the Cell Counting Kit-8 (CCK-8) assay. Luteolin-induced apoptosis was assessed by bivariate FITC-annexin V/PI assay, and Western blots were used to measured apoptotic proteins. Co-immunoprecipitation was used to determine the effect of luteolin on the interaction between Hsp90 and mutant EGF receptors. The effect of luteolin on the Akt/mTOR pathway was studied using Western blotting analysis. Its anti-tumour efficacy in vivo was examined in a mouse xenograft model.

Key Results

Luteolin exerted significant anti-tumourigenic effects on the EGF receptor L858R/T790M mutation and erlotinib-resistant NSCLC both at the cellular and animal levels. Mechanistically, luteolin induced degradation of the EGF receptor by inhibiting the association of Hsp90 with the mutant EGF receptor, and, therefore, prevented PI3K/Akt/mTOR signalling, which resulted in NSCLC cell apoptosis.

Conclusion and Implications

Luteolin may be a potential candidate for NSCLC therapy, especially for treatment of patients with acquired erlotinib-resistant NSCLC.     

Tumor suppressor in lung cancer-1 (TSLC1) mediated by dual-regulated oncolytic adenovirus exerts specific antitumor actions in a mouse model

Aim:

The tumor suppressor in lung cancer-1 (TSLC1) is a candidate tumor suppressor of lung cancer, and frequently inactivated in primary non-small cell lung cancer (NSCLC). In this study, we investigated the effects of TSLC1 mediated by a dual-regulated oncolytic adenovirus on lung cancer, and the mechanisms underlying the antitumor actions.

Methods:

The recombinant virus Ad·sp-E1A_(Δ24)-TSLC1 was constructed by inserting the TSLC1 gene into the dual-regulated Ad·sp-E1A_(Δ24) vector, which contained the survivin promoter and a 24 bp deletion within E1A. The antitumor effects of Ad·sp-E1A_(Δ24)-TSLC1 were evaluated in NCI-H460, A549, and H1299 lung cancer cell lines and the normal fibroblast cell line MRC-5, as well as in A549 xenograft model in nude mice. Cell viability was assessed using MTT assay. The expression of TSLC1 and activation of the caspase signaling pathway were detected by Western blot analyses. The tumor tissues from the xenograft models were examined using H&E staining, IHC, TUNEL, and TEM analyses.

Results:

Infection of A549 lung cancer cells with Ad·sp-E1A_(Δ24)-TSLC1 induced high level expression of TSLC1. Furthermore, the Ad·sp-E1A_(Δ24)-TSLC1 virus dose-dependently suppressed the viability of NCI-H460, A549, and H1299 lung cancer cells, and did not affect MRC-5 normal fibroblast cells. Infection of NCI-H460, A549, and H1299 lung cancer cells with Ad·sp-E1A_(Δ24)-TSLC1 induced apoptosis, and increased activation of caspase-8, caspase-3 and PARP. In A549 xenograft model in nude mice, intratumoral injection of Ad·sp-E1A_(Δ24)-TSLC1 significantly suppressed the tumor volume, and increased the survival rate (from less than 15% to 87.5% at d 60). Histological studies showed that injection of Ad·sp-E1A_(Δ24)-TSLC1 caused tumor cell apoptosis and virus particle propagation in tumor tissues.

Conclusion:

The oncolytic adenovirus Ad·sp-E1A_(Δ24)-TSLC1 exhibits specific antitumor effects, and is a promising agent for the treatment of lung cancer.     

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.     

Morin exerts neuroprotective actions in Parkinson disease models in vitro and in vivo

Aim:

To investigate the neuroprotective effects of morin on 1-methyl-4-phenylpyridinium ion (MPP⁺)-induced apoptosis in neuronal differentiated PC12 cells as well as in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of Parkinson disease (PD).

Methods:

PC12 cells were challenged with MPP⁺ in the presence or absence of morin. Cell viability was determined using MTT assay. Cell apoptosis was measured using flow cytometry. Generation of reactive oxygen species (ROS) was assayed using fluorescence assay. In an MPTP mouse model of PD, behavioral deficits, striatal dopamine content, and number of dopaminergic neurons were measured.

Results:

MPP⁺ induced apoptosis and ROS formation in PC12 cells. Concomitant treatment with morin (5-50 μmol/L) significantly attenuated the loss of cell viability and apoptosis when compared with MPP⁺ treatment alone. Morin also attenuated ROS formation induced by MPP⁺. MPTP induced permanent behavioral deficits and nigrostriatal lesions in mice. When administered prior to MPTP, morin (20 to 100 mg/kg) attenuated behavioral deficits, dopaminergic neuronal death and striatal dopamine depletion in the MPTP mouse model.

Conclusion:

The findings suggest that morin has neuroprotective actions both in vitro and in vivo, and may provide a novel therapeutic agent for the treatment of PD and other neurodegenerative diseases.     

FoxM1 mediated resistance to gefitinib in non-smallcell lung cancer cells

Aim:

Gefitinib is effective in only approximately 20% of patients with non-small-cell lung cancer (NSCLC), and the underlying mechanism remains unclear. FoxM1 is upregulated in NSCLC and associated with a poor prognosis in NSCLC patients. In this study, we examined the possible role of FoxM1 in gefitinib resistance and the related mechanisms.

Methods:

Gefitinib resistant human lung adenocarcinoma cell line SPC-A-1 and gefitinib-sensitive human lung mucoepidermoid carcinoma cell line NCI-H292 were used. mRNA and protein expression of FoxM1 and other factors were tested with quantitative RT PCR and Western blot analysis. RNA interference was performed to suppress FoxM1 expression in SPC-A-1 cells, and lentiviral infection was used to overexpress FoxM1 in H292 cells. MTT assay and flow cytometry were used to examine the proliferation and apoptosis of the cells.

Results:

Treatment of SPC-A-1 cells with gefitinib (1 and 10 μmol/L) upregulated the expression of FoxM1 in time- and concentration-dependent manners, while gefitinib (1 μmol/L) downregulated in H292 cells. In SPC-A-1 cells treated with gefitinib (1 μmol/L), the expression of several downstream targets of FoxM1, including survivin, cyclin B1, SKP2, PLK1, Aurora B kinase and CDC25B, were significantly upregulated. Overexpression of FoxM1 increased the resistance in H292 cells, while attenuated FoxM1 expression restored the sensitivity to gefitinib in SPC-A-1 cells by inhibiting proliferation and inducing apoptosis.

Conclusion:

The results suggest that FoxM1 plays an important role in the resistance of NSCLC cells to gefitinib in vitro. FoxM1 could be used as a therapeutic target to overcome the resistance to gefitinib.     

Gemcitabine combined with gum mastic causes potent growth inhibition and apoptosis of pancreatic cancer cells

Aim:

To investigate the antiproliferative and apoptotic effects of gemcitabine combined with gum mastic and the underlying mechanisms in human pancreatic cancer cell lines.

Methods:

Cell proliferation and apoptosis were examined using the methyl thiazolyl tetrazolium (MTT) assay and propidium iodine staining, respectively. The expression of Bcl-2, Bax, NF-κB p65 subunit, and IκBα protein was measured using Western blotting.

Results:

Gemcitabine 0.01−100 μg/mL inhibited cell proliferation and induced apoptosis in both pancreatic cancer BxPC-3 and COLO 357 cells. Gum mastic 40 μg/mL significantly potentiated the antiproliferative and apoptotic effects of gemcitabine 10 μg/mL after 72-h treatment. When cells were treated with gemcitabine in combination with gum mastic, the IκBα level was increased, whereas NF-κB activation was blocked; the expression of Bax protein was substantially increased, but Bcl-2 protein was down-regulated.

Conclusion:

Gemcitabine combined with gum mastic causes potent apoptosis in pancreatic cancer cells. The combination may be an effective therapeutic strategy for pancreatic cancer.     

Chloroquine potentiates the anti-cancer effect of lidamycin on non-small cell lung cancer cells in vitro

Aim： To assess the synergistic actions of lidamycin （LDM） and chloroquine （CQ）, a lysosomal enzyme inhibitor, in human non-small cell lung cancer （NSCLC） cells, and to elucidate the potential mechanisms. Methods： Human NSCLC cell lines A549 and H460 were treated with CQ and/or LDM. Cell proliferation was analyzed using MTI- assay and apoptosis was quantified using flow cytometry. Western blotting was used to detect the protein levels of caspase 3, PARP, Bcl-2, Bax, p53, LC3-1 and LC3-11. A H460 cell xenograft model in BALB/c nude mice was used to evaluate the anticancer efficacy of CQ and LDM in vivo. Results： Both LDM and CQ concentration-dependently suppressed the proliferation of A549 and H460 ceils in vitro （the ICso values of LDM were 1.70±0.75 and 0.043±0.026 nmol/L, respectively, while the IC50 values of CQ were 71.3±6.1 and 55.6±12.5 pmol/L, respectively）. CQ sensitized both NSCLC cell lines to LDM, and the majority of the coefficients of drug interaction （CDIs） for combination-doses were less than 1. The ratio of apoptosis of H460 cells induced by a combined treatment of CQ and LDM （77.0%±5.2%） was significantly higher than those caused by CQ （23.1%±4.2%） or by LDM （65.1%±4.1%） alone. Furthermore, the combined treatment markedly increased the cleaved PARP and cleaved caspase 3 in H460 cells, which were partly reversed by pretreatment with the caspase inhibitor zVAD.fmk, zVAD.fmk also partially reversed the inhibitory effect of the combination treatment on the proliferation of H460 cells. The combination therapy group had a notable increase in expression of Bax and a very slight decrease in expression of Bcl-2 and p53 protein. LDM alone scarcely affected the level of LC3-11 in H460 cells, but slightly reduced CQ-induced LC3-11 expression. 3-MA, an autophagy inhibitor also sensitized H460 cells to LDM. In nude mice bearing H460 cell xenograft, administration of LDM （25 pg/kg, iv） and CQ （60 mg/kg, ip） suppressed tumor growth by 57.14% and 73.02%, respectively. Conclusion： The synergistic anticancer effect of LDM and CQ in vitro results from activation of a caspase-dependent and p53- independent apoptosis pathway as well as inhibition of cytoprotective autophagy.     

S-allylcysteine,a garlic derivative,suppresses proliferation and induces apoptosis in human ovarian cancer cells in vitro

Aim： To investigate the effects of S-allylcysteine （SAC）, a water-soluble garlic derivative, on human ovarian cancer cells in vitro. Methods： Human epithelial ovarian cancer cell line A2780 was tested. Cell proliferation was examined with CCK-8 and colony formation assays. Cell cycle was analyzed with flow cytometry. Cell apoptosis was studied using Hoeohst 33258 staining and Annexin V/PI staining with flow cytometry. The migration and invasion of A2780 cells were examined with transwell and wound healing assays. The expression of relevant proteins was detected with Western blot assays. Results： SAC （1-100 mmol/L） inhibited the proliferation of A2780 cells in dose- and time-dependent manners （the ICsovalue was approximately 25 mmoVL at 48 h, and less than 6.25 mmol/L at 96 h）. Furthermore, SAC dose-dependently inhibited the colony formation of A2780 cells. Treatment of A2780 cells with SAC resulted in G/S phase arrest and induced apoptosis, accompanied by decreased expression of pro-caspase-3, Parp-1 and Bcl-2, and increased expression of active caspase-3 and Bax. SAC treatment significantly reduced the migration of A2780 cells, and markedly decreased the protein expression of Wnt5a, p-AKT and c-Jun, which were the key proteins involved in proliferation and metastasis. Conclusion： SAC suppresses proliferation and induces apoptosis in A2780 ovarian cancer cells in vitro.     

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.     

Mig-2 attenuates cisplatin-induced apoptosis of human glioma cells in vitro through AKT/JNK and AKT/p38 signaling pathways

Aim:

Mig-2 (also known as Kindlin-2 and FERMT2) is an important regulator of integrin activation and cell-extracellular matrix adhesion, and involved in carcinogenesis and tumor progression. The aim of this study was to investigate the role of mig-2 in cisplatin-induced apoptosis of human glioma cells in vitro.

Methods:

The expression of mig-2 was modulated in human glioma H4, HS 683 and U-87 MG cells by transfection with a plasmid carrying mig-2 or mig-2 siRNA. Cisplatin-induced apoptosis was detected using Annexin V/PI staining and flow cytometry, as well as MTS analyses. The expression of apoptosis-related or signaling proteins was examined using Western blotting analysis. H4 cells were transfected with plasmids carrying mig-2 mutants to determine the functional domain of mig-2.

Results:

In the 3 glioma cell lines tested, overexpression of mig-2 significantly attenuated cisplatin-induced apoptosis, whereas knock-down of mig-2 potentiated the apoptosis. The mechanisms of action of mig-2 were further addressed in H4 cells: overexpression of mig-2 markedly reduced cleaved caspase-9, caspase-8, caspase-3 and PARP, as well as p-JNK and p-p38, and increased p-AKT in cisplatin-treated H4 cells, whereas mig-2 siRNA reversely changed these apoptosis-related and signaling proteins. Furthermore, pretreatment with JNK inhibitor SP600125 and p38 inhibitor SB203580, or with AKT inhibitor {"type":"entrez-nucleotide","attrs":{"text":"LY294002","term_id":"1257998346","term_text":"LY294002"}}LY294002 abolished the effects of mig-2 on cisplaxtin-induced apoptosis. In H4 cells, GFP-mig-2 F3 plasmid that contained only the F3 subdomain showed the same efficiency in attenuating cisplatin-induced apoptosis, as the mig-2 wild-type vector did, whereas GFP-mig-2 (1-541) plasmid that lacked the F3 subdomain was inactive.

Conclusion:

Mig-2 significantly attenuates the antitumor action of cisplatin against human glioma cells in vitro through AKT/JNK and AKT/p38 signaling pathways. The F3 subdomain of mig-2 is necessary and sufficient for this effect.     

Bornyl caffeate induces apoptosis in human breast cancer cells in vitro via the ROS- and JNK-mediated pathways

Aim： To investigate the effects of bornyl caffeate discovered in several species of plant on human breast cancer cells in vitro and the underlying mechanisms.
Methods： Human breast cancer cell line MCF-7 and other tumor cell lines （T47D, HepG2, HeLa, and PC12） were tested. Cell viability was determined using MTT assay, and apoptosis was defined by monitoring the morphology of the nuclei and staining with Annexin V-FITC. Mitochondrial membrane potential （MMP） was measured using JC-1 under fluorescence microscopy. Intracellular reactive oxygen species （ROS） were assessed by flow cytometry. The expression of apoptosis-associated proteins was determined by Western blotting analysis.

Results： Bornyl caffeate （10, 25, and 50 μmol/L） suppressed the viability of MCF-7 cells in dose- and time-dependent manners, but neither caffeic acid nor borneol showed cytotoxicity at a concentration of 50 μmol/L. Bornyl caffeate also exerted cytotoxicity to HepG2, Hela, T47D, and PC12 cells. Bornyl caffeate dose-dependently induced apoptosis of MCF-7 cells, increased the expression of Bax and decreased the expression of Bcl-xl, resulting in the disruption of MMP and subsequent activation of caspase-3. Moreover, bornyl caffeate triggered the formation of ROS and activated p38 and c-Jun JNK. In MCF-7 cells, the cytotoxicity of bornyl caffeate was significantly attenuated by SB203580 （p38 inhibitor）, SP600125 （JNK inhibitor）, z-VAD （pan-caspase inhibitor） or the thiol antioxidant L-NAC.

Conclusion： Bornyl caffeate exerts non-selective cytotoxicity against cancer cells of different origin in vitro. The compound induces apoptosis in human breast cancer MCF-7 cells via the ROS- and JNK-mediated pathways.