Daidzein induces MCF-7 breast cancer cell apoptosis via the mitochondrial pathway

BackgroundIn order to study the anticancer effects and cellular apoptosis pathways induced by daidzein.Materials and methodsWe used the human MCF-7 breast cancer cell line as a model and examined the apoptosis by Hoechst–propidium iodide staining fluorescence imaging and flow cytometry.ResultsOur data indicated that daidzein induces antiproliferative effects in a concentration- and time-dependent manner. We demonstrated that daidzein-induced apoptosis in MCF-7 cells was initiated by the generation of reactive oxygen species (ROS). Furthermore, we showed that this daidzein-induced ROS generation was accompanied by disruption of mitochondrial transmembrane potential, down-regulation of bcl-2, and up-regulation of bax, which led to the release of cytochrome C from the mitochondria into the cytosol, which, in turn, resulted in the activation of caspase-9 and caspase-7, and ultimately in cell death. The induction of the mitochondrial caspase-dependent pathway was confirmed by pretreatment with pan-caspase inhibitor z-VAD-fmk and antioxidant N-acetyl-L-cysteine.ConclusionAccordingly, daidzein could induce breast cancer cell apoptosis through the mitochondrial caspase-dependent cell death pathway.     

微量化学发光法测定恶性肿瘤患者血清中超氧化物岐化酶的初步探讨

Superoxide dismutase (SOD) activity in blood of cancer patients were detected by microchemical luminescence. The results showed that SOD activity was closely related to the development of tumor. 151 cancer patients were divided into 5 groups: lung cancer, digestive tract cancer, breast cancer, gynecologic cancer and other cancers. The level of SOD in the blood in each group was higher than that in healthy adult controls. There was significant difference in the positive rate: 73.68% in breast cancer, 60.78% in digestive tract cancer, 60% in lung cancer, 51.52% in gynecologic cancer and 73.91% in other cancers. Thirty-one of these patients had low SOD due to radiotherapy or chemotherapy before determination. The important role of SOD in the development of cancer and its mechanism of preventing cancer are preliminarily analysed and discussed.     

丙戊酸钠通过激活内源性凋亡途径诱导乳腺癌细胞凋亡的实验研究

目的探讨丙戊酸钠（VPA）诱导乳腺癌细胞凋亡的作用。方法乳腺癌细胞株MCF-7细胞分为0.75～4.0 mmoL/L VPA实验组、对照组（不加VPA）及VPA与caspase抑制剂共同作用组。Annexin V-PI双染法流式细胞术检测细胞凋亡,间接免疫荧光法定量分析及分光光度法检测caspase- 3、caspase-8、caspase-9蛋白丰度和活性,探讨VPA诱导凋亡的机制,同时检测VPA与caspase-3、caspase- 8、caspase-9特异性抑制剂协同作用后细胞凋亡的变化来加以验证。结果各浓度VPA干预MCF-7细胞48 h后,细胞凋亡率显著增加,caspase-3、caspase-9活性升高、蛋白表达明显上调,与对照组相比有显著差异（F=552.1、610.9、312.8、222.8、70.3,均P〈0.001）;而caspase-8活性及蛋白表达未见明显改变;1.5、3.0 mmol/L VPA与caspase-3、caspase-9相应特异性抑制剂共同作用组,细胞凋亡率均较VPA组显著降低（t=109.0、28.7、18.7、32.3,均P〈0.005）;VPA与caspase-8特异性抑制剂共同作用组细胞凋亡率与VPA组比较无明显改变（t=1.03、2.32,均P〉0.05）。结论VPA可通过激活caspase-9介导的内源性凋亡途径,明显诱导乳腺癌细胞凋亡,具有较好的临床应用价值。     

Sodium selenite induces apoptosis by generation of superoxide via the mitochondrial-dependent pathway in human prostate cancer cells

Purpose  Studies have demonstrated that selenium supplementation reduces the incidence of cancer, particularly prostate cancer. Evidence from experimental studies suggests that apoptosis is a key event in cancer chemoprevention by selenium and reactive oxygen species play a role in induction of apoptosis by selenium compounds. The current study was designed to investigate the role of superoxide and mitochondria in selenite-induced apoptosis in human prostate cancer cells. Methods  LNCaP cells were transduced with adenoviral constructs to overexpress four primary antioxidant enzymes: manganese superoxide dismutase (MnSOD), copper-zinc superoxide dismutase (CuZnSOD), catalase (CAT), or glutathione peroxidase 1 (GPx1). Cell viability, apoptosis, and superoxide production induced by sodium selenite were analyzed by the MTT assay, chemiluminescence, flow cytometry, western blot analysis, and Hoechst 33342 staining following overexpression of these antioxidant enzymes. Results  Our study shows the following results: (1) selenite induced cancer cell death and apoptosis by producing superoxide radicals; (2) selenite-induced superoxide production, cell death, and apoptosis were inhibited by overexpression of MnSOD, but not by CuZnSOD, CAT, or GPx1; and (3) selenite treatment resulted in a decrease in mitochondrial membrane potential, release of cytochrome c into the cytosol, and activation of caspases 9 and 3, events that were suppressed by overexpression of MnSOD. Conclusions  This study demonstrates that selenite induces cell death and apoptosis by production of superoxide in mitochondria and activation of the mitochondrial apoptotic pathway and MnSOD plays an important role in protection against prooxidant effects of superoxide from selenite. The data suggest that superoxide production in mitochondria is, at least in part, a key event in selenium-induced apoptosis in prostate cancer cells.     

Silymarin inhibits proliferation of human breast cancer cells via regulation of the MAPK signaling pathway and induction of apoptosis

Silymarin is a purified mixture of four isomeric flavonoids extracted from the seeds and fruit of the milk thistle plant, Silybum marianus (L.). Silymarin exhibits a wide variety of biological effects and is commonly used in traditional medicine. Therefore, the anticancer effects of silymarin on human breast cancer cells were investigated to determine its pharmacological mechanisms in vitro and in vivo. The viability and proliferation of MDA-MB- 231 and MCF-7 breast cancer cells were investigated using MTT and wound healing assays. Silymarin decreased the viability and proliferation of MDA-MB-231 and MCF-7 cells in a concentration-dependent manner. The number of apoptotic bodies, as shown by DAPI staining, was increased in a concentration-dependent manner, indicating that silymarin induces apoptosis. Additionally, changes in the expression levels of apoptosis-related proteins were demonstrated in human breast cancer cells using western blotting. Silymarin increased the levels of Bax, cleaved poly-ADP ribose polymerase, cleaved caspase-9 and phosphorylated (p-)JNK, and decreased the levels of Bcl-2, p-P38 and p-ERK1/2. Furthermore, the inhibitory effects of silymarin on MCF-7 tumor growth were investigated. In mice treated with silymarin for 3 weeks (25 and 50 mg/kg), MCF-7 tumor growth was inhibited without organ toxicity. In MCF-7 tumors, silymarin induced apoptosis and decreased p-ERK1/2 levels, as assessed using a TUNEL assay and immunohistochemistry. These results indicated that silymarin inhibited breast cancer cell proliferation both in vitro and in vivo by modulating the MAPK signaling pathway. Therefore, silymarin may potentially be used as a chemo-preventive or therapeutic agent.     

Variation in the manganese superoxide dismutase gene (SOD2) is not a major cause of radiotherapy complications in breast cancer patients.

BACKGROUND AND PURPOSE: Small proportions of patients receiving radiotherapy develop marked long-term radiation damage. It is thought that this is due, at least in part, to intrinsic differences in cellular radiosensitivity, but the underlying mechanism is unknown. Reactive oxygen species are involved in cellular radiation damage, hence inter-individual differences in free radical detoxification may be related to radiosensitivity. Within mitochondria manganese superoxide dismutase (MnSOD) provides a major defence against oxidative damage by reactive oxygen species. MnSOD has been linked to expression of malignant phenotype and apoptosis and polymorphic variation in the gene, SOD2 to risk of breast cancer. MATERIALS AND METHODS: Forty-one breast cancer patients developing marked changes in breast appearance after radiotherapy and 39 patients who showed no clinically detectable reaction after radiotherapy were analyzed for germline sequence variation in SOD2. RESULTS: The Ala-9Val polymorphism was detected, but no other sequence variants were detected in SOD2. Both alleles of the Ala-9Val polymorphism were equally distributed between the two patient groups. CONCLUSIONS: Sequence variation in SOD2 is not the major cause of radiotherapy complications in women with breast cancer.     

Serum copper/zinc superoxide dismutase (Cu/Zn SOD) and gastric cancer risk: a case-control study.

We conducted a case-control study to evaluate the association between serum levels of copper/zinc superoxide dismutase (Cu/Zn SOD) and the risk of gastric cancer. Cases were 214 patients who had been diagnosed with gastric cancer and controls were 120 persons who underwent medical checkups. Serum levels of Cu/Zn SOD were determined by enzyme-linked immunosorbent assay (ELISA). Compared with the lowest quartile, the OR (odds ratio) was 4.54 (95% CI (confidence interval), 1.62 - 12.66) for the third quartile and 15.75 (95% CI, 5.84 - 42.46) for the highest quartile. With both early and advanced cancers, as well as with the intestinal and diffuse types, a significant increase in risk was observed with increasing levels of serum Cu/Zn SOD. Our case-control study showed that serum levels of Cu/Zn SOD were significantly elevated in gastric cancer patients compared with apparently healthy controls, and higher Cu/Zn SOD levels may be associated with an increased risk of gastric cancer.     

Effects of manganese superoxide dismutase (MnSOD) expression on regulation of esophageal cancer cell growth and apoptosis in vitro and in nude mice

Manganese superoxide dismutase (MnSOD) catalyzes superoxide radical (O₂ ^?) into hydrogen peroxide (H₂O₂), which is further catalyzed by the combined action of glutathione peroxidase (GPx) and catalase (CAT) into water and oxygen. MnSOD plays a role in cell protection from superoxide damage. This study aimed to investigate the effects of MnSOD on regulation of esophageal squamous cell carcinoma cell growth, apoptosis, and cell cycle distribution in vitro and tumor formation and growth in nude mouse xenografts. The data showed that differential levels of MnSOD expression had different effects on tumor cell proliferation, apoptosis, plating efficiency (PE), and cell cycle distribution in vitro and tumor formation and growth in nude mice. In particular, high levels of MnSOD expression promoted TE-1 cell growth and PE rate in vitro and in nude mice, whereas moderate MnSOD expression suppressed tumor cell growth and PE rate but induced more cell apoptosis. Thus, these data demonstrated the dual effects of MnSOD protein in esophageal squamous cell carcinoma and further study will confirm these current data.     

Metformin inhibits estrogen‐dependent endometrial cancer cell growth by activating the AMPK–FOXO1 signal pathway

Metformin is an oral biguanide commonly used for treating type II diabetes and has recently been reported to possess antiproliferative properties that can be exploited for the prevention and treatment of a variety of cancers. The mechanisms underlying this effect have not been fully elucidated. Our study shows a marked loss of AMP‐activated protein kinase (AMPK) phosphorylation and nuclear human Forkhead box O1 (FOXO1) protein in estrogen‐dependent endometrial cancer (EC) tumors compared to normal control endometrium. Metformin treatment suppressed EC cell growth in a time‐dependent manner in vitro; this effect was cancelled by cotreatment with an AMPK inhibitor, compound C. Metformin decreased FOXO1 phosphorylation and increased FOXO1 nuclear localization in Ishikawa and HEC‐1B cells, with non‐significant increase in FOXO1 mRNA expression. Moreover, compound C blocked the metformin‐induced changes of FOXO1 and its phosphorylation protein, suggesting that metformin upregulated FOXO1 activity by AMPK activation. Similar results were obtained after treatment with insulin. In addition, transfection with siRNA for FOXO1 cancelled metformin‐inhibited cell growth, indicating that FOXO1 mediated metformin to inhibit EC cell proliferation. A xenograft mouse model further revealed that metformin suppressed HEC‐1B tumor growth, accompanied by downregulated ki‐67 and upregulated AMPK phosphorylation and nuclear FOXO1 protein. Taken together, these data provide a novel mechanism of antineoplastic effect for metformin through the regulation of FOXO1, and suggest that the AMPK–FOXO1 pathway may be a therapeutic target to the development of new antineoplastic drugs.     

Exogenous morphine inhibits human gastric cancer MGC- 803 cell growth by cell cycle arrest and apoptosis induction

Morphine is not only an analgesic treating pain for patients with cancer but also a potential anticancer drug inhibiting tumor growth and proliferation. To gain better insight into the involvement of morphine in the biological characteristics of gastric cancer, we investigated effects on progression of gastric carcinoma cells and the expression of some apoptosis-related genes including caspase-9, caspase-3, survivin and NF-κB using the MGC-803 human gastric cancer cell line. The viability of cells was assessed by MTT assay, proliferation by colony formation assay, cell cycle progression and apoptosis by flow cytometry and ultrastructural alteration by transmission electron microscopy. The influences of morphine on caspase-9, caspase-3, survivin and NF-κB were evaluated by semi-quantitative RT-PCR and Western blot. Our data showed that morphine could significantly inhibit cell growth and proliferation and cause cell cycle arrest in the G2/M phase. MGC-803 cells which were incubated with morphine also had a higher apoptotic rate than control cells. Morphine also led to morphological changes of gastric cancer cells. The mechanism of morphine inhibiting gastric cancer progression in vitro might be associated with activation of caspase-9 and caspase-3 and inhibition of survivin and NF-κB.     

Antisense oligonucleotide targeting Livin induces apoptosis of human bladder cancer cell via a mechanism involving caspase 3

Background and Aim

in recent years, Livin, a new member of IAPs family, is found to be a key molecule in cancers. Researchers consider Livin may become a new target for tumor therapy; however, the role of it in bladder cancer is still unclear. The purpose of this article is to investigate Antisense Oligonucleotide (ASODN) of Livin on treating bladder cancer cell and underlying mechanisms.

Methods

Phosphorathioate modifying was used to synthesize antisense oligonucleotides targeting Livin, followed by transfection into human bladder cancer cell 5637. After transfection, Livin mRNA and protein level, cell proliferation and apoptosis changes, caspase3 level and its effect on human bladder cancer transplantable tumor in nude mice were measured.

Result

results showed Livin ASODN effectively inhibited Livin expression and tumor cell proliferation, and these effects probably through enhanced caspase3 activity and apoptosis of tumor cells. In nude mice transplantable tumor model, Livin expressions were inhibited meanwhile caspase3 expression was increased. Tumor growth slowed down and apoptosis was enhanced.

Conclusion

Our data suggest that Livin plays an important role in inhibiting apoptosis of bladder cancer cells. Livin ASODN may promote cell apoptosis, inhibit bladder cancer growth, and become one of the methods of gene therapy for bladder cancer.     

Mitochondrial dysfunction in some triple-negative breast cancer cell lines: role of mTOR pathway and therapeutic potential

Introduction

Triple-negative breast cancer (TNBC) is a subtype of highly malignant breast cancer with poor prognosis. TNBC is not amenable to endocrine therapy and often exhibit resistance to current chemotherapeutic agents, therefore, further understanding of the biological properties of these cancer cells and development of effective therapeutic approaches are urgently needed.

Methods

We first investigated the metabolic alterations in TNBC cells in comparison with other subtypes of breast cancer cells using molecular and metabolic analyses. We further demonstrated that targeting these alterations using specific inhibitors and siRNA approach could render TNBC cells more sensitive to cell death compared to other breast cancer subtypes.

Results

We found that TNBC cells compared to estrogen receptor (ER) positive cells possess special metabolic characteristics manifested by high glucose uptake, increased lactate production, and low mitochondrial respiration which is correlated with attenuation of mTOR pathway and decreased expression of p70S6K. Re-expression of p70S6K in TNBC cells reverses their glycolytic phenotype to an active oxidative phosphorylation (OXPHOS) state, while knockdown of p70S6K in ER positive cells leads to suppression of mitochondrial OXPHOS. Furthermore, lower OXPHOS activity in TNBC cells renders them highly dependent on glycolysis and the inhibition of glycolysis is highly effective in targeting TNBC cells despite their resistance to other anticancer agents.

Conclusions

Our study shows that TNBC cells have profound metabolic alterations characterized by decreased mitochondrial respiration and increased glycolysis. Due to their impaired mitochondrial function, TNBC cells are highly sensitive to glycolytic inhibition, suggesting that such metabolic intervention may be an effective therapeutic strategy for this subtype of breast cancer cells.     

Proteomic based identification of manganese superoxide dismutase 2 (SOD2) as a metastasis marker for oral squamous cell carcinoma

Metastasis is a critical event in oral squamous cell carcinoma (OSCC) progression. To identify proteomic biomarkers for OSCC metastasis, 3 paired OSCC cell lines (UM1/UM2, 1386Tu/1386Ln, 686Tu/686Ln) with different metastatic potential were examined. Among those 3 cell lines, UM1, 1386Ln and 686Ln exhibited a higher degree of metastatic potential than their paired cell lines UM2, 1386Tu and 686Tu, respectively, as measured using an in vitro cell invasion assay. A total of 40 differentially expressed proteins were identified using 2D-PAGE/MS proteomic approach. Selected protein candidates (superoxide dismutase 2 and heat shock protein 27) were further investigated by immuno-histochemistry (IHC) method using independent OSCC patient tissue samples. The statistically significantly increases in IHC staining for manganese superoxide dismutase 2 (SOD2) were observed in lymph node metastatic disease when compared with the paired primary OSCC. Our results thus indicated that elevated SOD2 levels is associated with lymph node metastasis in OSCC and may provide predictive values for diagnosis of metastasis.     

Arginase activity in human breast cancer cell lines: N(omega)-hydroxy-L-arginine selectively inhibits cell proliferation and induces apoptosis in MDA-MB-468 cells

L-Arginine is the common substrate for two enzymes, arginase and nitric oxide synthase (NOS). Arginase converts L-arginine to L-ornithine, which is the precursor of polyamines, which are essential components of cell proliferation. NOS converts L-arginine to produce NO, which inhibits proliferation of many cell lines. Various human breast cancer cell lines were initially screened for the presence of arginase and NOS. Two cell lines, BT-474 and MDA-MB-468, were found to have relatively high arginase activity and very low NOS activity. Another cell line, ZR-75-30, had the highest NOS activity and comparatively low arginase activity. The basal proliferation rates of MDA-MB-468 and BT-474 were found to be higher than the ZR-75-30 cell line. N-Hydroxy-L-arginine (NOHA), a stable intermediate product formed during conversion of L-arginine to NO, inhibited proliferation of the high arginase-expressing MDA-MB-468 cells and induced apoptosis after 48 h. NOHA arrested these cells in the S phase, increased the expression of p21, and reduced spermine content. These effects of NOHA were not observed in the ZR-75-30 cell line, which expresses high NOS and relatively low arginase. The effects of NOHA were antagonized in the presence of L-ornithine (500 microM), which suggests that in MDA-MB-468 cell line, the arginase pathway is very important for cell proliferation. Inhibition of the arginase pathway led to depletion of intracellular spermine and apoptosis as observed by terminal deoxynucleotidyl transferase (Tdt)-mediated nick end labeling assay and induction of caspase 3. In contrast, the ZR-75-30 cell line maintained its viability and its L-ornithine and spermine levels in the presence of NOHA. We conclude that NOHA has antiproliferative and apoptotic actions on arginase-expressing human breast cancer cells that are independent of NO.     

Estimation of serum tumor necrosis factor-α and tumor tissue superoxide dismutase (SOD) activity in the prognosis of human colorectal cancer

Background Serum tumor necrosis factor-α (TNF) levels were estimated before surgery and tissue SOD levels were determined postoperatively as a means to gauge future prognosis in colorectal cancer patients. Methods We examined TNF levels, the ability of neutrophils to produce active oxygen, and cancer tissue superoxide dismutase (SOD) activity. We then investigated the relationships among these mediators and survival rates in 75 patients with colorectal cancer. Results Twenty cases were positive for TNF, varying from 6.9 to 472 pg/mL. In the TNF-positive group, all cases except 1 stage III case and those of stage IV were alive. In the TNF-negative group, 29% of stage II, 63% of stage III, and all stage IV patients died. The survival rate except for stage I and stage IV cases was significantly higher in the TNF-positive group, compared with the TNF-negative group (P<0.05). SOD activities of the TNF-negative group were higher than those in the TNF-positive stage II and III group. In the TNF-negative patients, SOD activities were higher in the patients who died than in the survivors. The ability of neutrophils to produce active oxygen in survivors was higher than in the patients who died. Conclusion TNF levels before surgery and tissue SOD activity can influence the postoperative prognosis. The prognosis in patients who are TNF-positive with low tissue SOD activity and neutrophils with a normal ability to produce active oxygen is excellent. Immunopotentiating therapy may be imperative for stage II and III TNF-negative patients with high tissue SOD activity.     

Insulin-like growth factor binding protein-1 (IGFBP-1) inhibits breast cancer cell motility

The breast cancer malignant phenotype is regulated by steroid hormones and peptide growth factors. We have shown previously that insulin-like growth factor-I (IGF-I) stimulates cell motility in a metastatic cell line, MDA-231BO. In this study, we show that neutralization of IGF action by a type I IGF receptor (IGFR1) blocking antibody or neutralization of IGF-I by IGFBP-1 reduced cell motility. However, in addition to inhibiting IGF effects, IGFBP-1 also diminished basal motility. Because IGFBP-1 contains a RGD motif important in binding of fibronectin to its alpha 5 beta 1 integrin receptor, we examined the effect of inhibiting integrin function on cell motility. As expected, disruption of fibronectin-integrin interactions interrupted basal motility in MDA-231BO cells. In addition, disruption of integrin function by an alpha 5 beta 1 blocking peptide also inhibited IGF stimulation of cell motility. To determine whether integrin function could interfere with IGF signaling, we used an alpha 5 beta 1 blocking peptide to show that in MDA-231BO cells integrin occupancy appeared necessary for phosphorylation of insulin receptor substrate-2 but not for IGFR1 activation. We conclude that IGFR1 and integrin action are linked in these breast cancer cells as disruption of integrin binding to its receptor influences IGF signaling pathways. Moreover, IGFBP-1 could have dual effects on cancer cell motility by disrupting both receptor systems.     

Small molecular anticancer agent SKLB703 induces apoptosis in human hepatocellular carcinoma cells via the mitochondrial apoptotic pathway invitro and inhibits tumor growth invivo

Inducing apoptosis is a promising therapeutic approach to overcome cancer. Here we described that a novel synthesized compound, 3-amino-N-(4-chlorobenzyl)-6-(3-methoxyphenyl)thieno[2,3-b]pyridine-2-carboxamide (SKLB703), exhibits antitumor activity via inducing apoptosis both invitro and invivo. Our results showed that SKLB703 inhibited the proliferation of a panel of human cancer cell lines, and human hepatocellular carcinoma cell line HepG2 was the most sensitive. The proliferation inhibitory effect of SKLB703 was associated with its apoptosis-inducing effect by activating caspase-3 and caspase-9 rather than caspase 8. Exposure of HepG2 to SKLB703 also resulted in Bax upregulation, Bcl-2 downregulation, cytochrome c release and mitochondrial transmembrane potential change in mitochondrial apoptotic pathway. Moreover, the decrease of phosphorylated p 44/42 mitogen-activated protein kinase and phosphorylated Akt was observed. SKLB703 suppressed the growth of established tumors in xenograft models in mice, whereas no toxicity was exhibited. TUNAL analysis showed that SKLB703 induced HepG2 tumor apoptosis. Taken together, the present study demonstrates that SKLB730 exhibits its antitumor activity through inducing apoptosis via mitochondrial apoptotic pathway. Its potential to be a candidate of anticancer agent is worth being further investigated.     

Metformin inhibits growth and enhances radiation response of non-small cell lung cancer (NSCLC) through ATM and AMPK

Background:

We examined the potential of metformin (MET) to enhance non-small cell lung cancer (NSCLC) responses to ionising radiation (IR).

Methods:

Human NSCLC cells, mouse embryonic fibroblasts from wild-type and AMP-activated kinase (AMPK) α1/2-subunit^−/− embryos (AMPKα1/2^−/−-MEFs) and NSCLC tumours grafted into Balb/c-nude mice were treated with IR and MET and subjected to proliferation, clonogenic, immunoblotting, cell cycle and apoptosis assays and immunohistochemistry (IHC).

Results:

Metformin (2.5 μℳ–5 mℳ) inhibited proliferation and radio-sensitised NSCLC cells. Metformin (i) activated the ataxia telengiectasia-mutated (ATM)–AMPK–p53/p21^cip1 and inhibited the Akt–mammalian target of rapamycin (mTOR)–eIF4E-binding protein 1 (4EBP1) pathways, (ii) induced G1 cycle arrest and (iii) enhanced apoptosis. ATM inhibition blocked MET and IR activation of AMPK. Non-small cell lung cancer cells with inhibited AMPK and AMPKα1/2^−/−-MEFs were resistant to the antiproliferative effects of MET and IR. Metformin or IR inhibited xenograft growth and combined treatment enhanced it further than each treatment alone. Ionising radiation and MET induced (i) sustained activation of ATM–AMPK–p53/p21^cip1 and inhibition of Akt–mTOR–4EBP1 pathways in tumours, (ii) reduced expression of angiogenesis and (iii) enhanced expression of apoptosis markers.

Conclusion:

Clinically achievable MET doses inhibit NSCLC cell and tumour growth and sensitise them to IR. Metformin and IR mediate their action through an ATM–AMPK-dependent pathway. Our results suggest that MET can be a clinically useful adjunct to radiotherapy in NSCLC.     

Salvia miltiorrhiza inhibits cell growth and induces apoptosis in human hepatoma HepG(2) cells

Salvia miltiorrhiza (SM) is a traditional Chinese herbal medicine, commonly used to treat liver diseases in China for centuries. Several earlier studies have indicated that SM exhibits anti-tumor properties, but its mechanism remains to be elucidated. In this study, we evaluated the molecular mechanism of SM in a human hepatoma cell line, HepG(2). Our results show that SM exerted clear cytotoxic effects, and strongly inhibited the proliferation of HepG(2) cells. It was also observed that SM treatment caused apoptotic cell death as evaluated by: (a), morphological changes by using acridine orange/ethidium bromide staining; (b), DNA fragmentation by TdT-mediated dUTP nick end labeling (TUNEL); and (c), sub-G(1) cell analysis. Furthermore, depletion of intracellular glutathione (GSH) and reduction of mitochondrial membrane potential were found to be involved in the initiation of apoptosis by SM.