Peroxide Is a Key Mediator of Bcl-2 Down-Regulation and Apoptosis Induction by Cisplatin in Human Lung Cancer Cells

Stimulatory Effects of Extracellular Vesicles Derived from Leuconostoc holzapfelii That Exists in Human Scalp on Hair Growth in Human Follicle Dermal Papilla Cells

Human hair follicle dermal papilla cells (HFDPCs) located in hair follicles (HFs) play a pivotal role in hair follicle morphogenesis, hair cycling, and hair growth. Over the past few decades, probiotic bacteria (PB) have been reported to have beneficial effects such as improved skin health, anti-obesity, and immuno-modulation for conditions including atopic dermatitis and inflammatory bowel disease (IBD). PB can secrete 50~150 nm sized extracellular vesicles (EVs) containing microbial DNA, miRNA, proteins, lipids, and cell wall components. These EVs can regulate communication between bacteria or between bacteria and their host. Although numerous biological effects of PB-EVs have been reported, the physiological roles of Leuconostoc holzapfelii (hs-Lh), which is isolated from human scalp tissue, and the extracellular vesicles derived from them (hs-LhEVs) are largely unknown. Herein, we investigated the effects of hs-LhEVs on hair growth in HFDPCs. We show that hs-LhEVs increase cell proliferation, migration, and regulate the cell cycle. Furthermore, hs-LhEVs were found to modulate the mRNA expression of hair-growth-related genes in vitro. These data demonstrate that hs-LhEVs can reduce apoptosis by modulating the cell cycle and promote hair growth by regulation via the Wnt/β-catenin signal transduction pathway.

Killing by Degradation: Regulation of Apoptosis by the Ubiquitin-Proteasome-System

Apoptosis is a cell suicide process that is essential for development, tissue homeostasis and human health. Impaired apoptosis is associated with a variety of human diseases, including neurodegenerative disorders, autoimmunity and cancer. As the levels of pro- and anti-apoptotic proteins can determine the life or death of cells, tight regulation of these proteins is critical. The ubiquitin proteasome system (UPS) is essential for maintaining protein turnover, which can either trigger or inhibit apoptosis. In this review, we will describe the E3 ligases that regulate the levels of pro- and anti-apoptotic proteins and assisting proteins that regulate the levels of these E3 ligases. We will provide examples of apoptotic cell death modulations using the UPS, determined by positive and negative feedback loop reactions. Specifically, we will review how the stability of p53, Bcl-2 family members and IAPs (Inhibitor of Apoptosis proteins) are regulated upon initiation of apoptosis. As increased levels of oncogenes and decreased levels of tumor suppressor proteins can promote tumorigenesis, targeting these pathways offers opportunities to develop novel anti-cancer therapies, which act by recruiting the UPS for the effective and selective killing of cancer cells.

Cisplatin-induced hydroxyl radicals mediate pro-survival autophagy in human lung cancer H460 cells

Background

Accumulated evidence demonstrates cisplatin, a recommended chemotherapy, modulating pro-survival autophagic response that contributes to treatment failure in lung cancer patients. However, distinct mechanisms involved in cisplatin-induced autophagy in human lung cancer cells are still unclear.

Results

Herein, role of autophagy in cisplatin resistance was indicated by a decreased cell viability and increased apoptosis in lung cancer H460 cells pre-incubated with wortmannin, an autophagy inhibitor, prior to treatment with 50 µM cisplatin for 24 h. The elevated level of hydroxyl radicals detected via flow-cytometry corresponded to autophagic response, as evidenced by the formation of autophagosomes and autolysosomes in cisplatin-treated cells. Interestingly, apoptosis resistance, autophagosome formation, and the alteration of the autophagic markers, LC3-II/LC3-I and p62, as well as autophagy-regulating proteins Atg7 and Atg3, induced by cisplatin was abrogated by pretreatment of H460 cells with deferoxamine, a specific hydroxyl radical scavenger. The modulations in autophagic response were also indicated in the cells treated with hydroxyl radicals generated via Fenton reaction, and likewise inhibited by pretreatment with deferoxamine.

Conclusions

In summary, the possible role of hydroxyl radicals as a key mediator in the autophagic response to cisplatin treatment, which was firstly revealed in this study would benefit for the further development of novel therapies for lung cancer.

Role of Bcl-2 Family Proteins in Photodynamic Therapy Mediated Cell Survival and Regulation

Photodynamic therapy (PDT) is a treatment modality that involves three components: combination of a photosensitizer, light and molecular oxygen that leads to localized formation of reactive oxygen species (ROS). The ROS generated from this promising therapeutic modality can be lethal to the cell and leads to consequential destruction of tumor cells. However, sometimes the ROS trigger a stress response survival mechanism that helps the cells to cope with PDT-induced damage, resulting in resistance to the treatment. One preferred mechanism of cell death induced by PDT is apoptosis, and B-cell lymphoma 2 (Bcl-2) family proteins have been described as a major determinant of life or death decision of the death pathways. Apoptosis is a cellular self-destruction mechanism to remove old cells through the biological event of tissue homeostasis. The Bcl-2 family proteins act as a critical mediator of a life–death decision of cells in maintaining tissue homeostasis. There are several reports that show cancer cells developing resistance due to the increased interaction of the pro-survival Bcl-2 family proteins. However, the key mechanisms leading to apoptosis evasion and drug resistance have not been adequately understood. Therefore, it is critical to understand the mechanisms of PDT resistance, as well as the Bcl-2 family proteins, to give more insight into the treatment outcomes. In this review, we describe the role of Bcl-2 gene family proteins’ interaction in response to disease progression and PDT-induced resistance mechanisms.

Involvement of ER stress and reactive oxygen species generation in anti-cancer effect of CKD-516 for lung cancer

PURPOSE

CKD-516 (Valecobulin), a vascular-disrupting agent, inhibits microtubule elongation. We evaluated the effect of CKD-516 on lung cancer cells and the underlying molecular mechanisms.

METHODS

The effects of S516, an active metabolite of CKD-516, were evaluated in HUVECs and three lung cancer cell lines and by a microtubule polymerization assay. Tubulin cross-linking was used to identify the binding site of S516 on tubulin, and Western blotting was performed to identify the intracellular pathways leading to cell death. Subcutaneous lung cancer xenograft models were used to assess the in vivo effect of CKD-516 on tumor growth.

RESULTS

S516 targeted the colchicine binding site on β-tubulin. In lung cancer cells, S516 increased endoplasmic reticulum (ER) stress and induced reactive oxygen species (ROS) generation by mitochondria and the ER. In addition, CKD-516 monotherapy strongly inhibited the growth of lung cancer xenograft tumors and exerted a synergistic effect with carboplatin.

CONCLUSION

The findings suggest that CKD-516 exerts an anticancer effect in company with inducing ER stress and ROS production via microtubule disruption in lung cancer cells. CKD-516 may thus have therapeutic potential for lung cancer.

Antioxidant effect of sildenafil: Potential hepatoprotection via differential expression of mitochondrial proteins in apolipoprotein E knockout mice

BACKGROUND

High plasma cholesterol levels are able to trigger several pathophysiological events, including inflammation, cell damage and especially oxidative stress. Previously, studies have shown that sildenafil exhibited antioxidant effects in several experimental models. Here we evaluate the role of sildenafil in liver redox equilibrium of apolipoprotein E knockout (apoE-KO) mice.

METHODS

ApoE-KO mice were divided in two groups: one group received the PDE5 inhibitor sildenafil (40 mg/kg/day) for 3 weeks (apoE-KO + Sil) and was compared to a second group of apoE-KO mice, which received only the vehicle (water) for 3 weeks (apoE-KO). Control group (C57 mice) received only a standard chow diet. At the age of 18 weeks, mice livers were collected for the measurement of intracellular ROS levels and apoptotic cells by flow cytometry analysis, and mitochondria isolation for proteomic analysis.

RESULTS

Compared to the control group, liver cells from apoE-KO presented some typical redox imbalance features: higher levels of intracellular ROS (global oxidative stress ˜60%, superoxide anion ˜82%, and peroxynitrite/hydroxyl radical ˜53%), higher amounts of apoptotic cells (up to ˜19%) and higher mitochondrial intensity of catalase (+339%) and transferrin spots (+914%). After treatment with sildenafil, apoE-KO presented ROS levels and the number of apoptotic cells similar to those observed in C57. In addition, when compared to apoE-KO, apoE-KO + Sil showed lower spots volumes of catalase (-23%) and transferrin (-71%) and up-regulation of urate oxidase (+94%).

CONCLUSION

The treatment with sildenafil is able to induce beneficial changes in liver mitochondrial protein dynamics, which restores the redox homeostasis contributing to a potential hepatoprotection.

Decreased Lung Tumor Development in SwAPP Mice through the Downregulation of CHI3L1 and STAT 3 Activity via the Upregulation of miRNA342-3p

We previously found that lung tumor development was reduced in a presenilin (PS) Alzheimer’s disease (AD) mouse model. Here, we investigated whether this reducing effect could occur in a different AD mouse model. We investigated urethane-induced (1 mg/g) lung tumor development and melanoma growth in Swedish amyloid precursor protein (SwAPP) transgenic mice. The expression of chitinase-3-like-1 (Chi3L1) increased during lung tumor development and melanoma growth, which was accompanied by an increase in the activity of signal transducer and activator of transcription 3 (STAT3) and the downregulation of miRNA342-3p in wild-type mice. Like tumor development, the expression of Chi3L1 and STAT3 activity was reduced in the SwAPP mice, whereas the expression of miRNA342-3p was upregulated. In addition, Chi3L1 knockdown in the lung cancer and melanoma tissues reduced cancer cell growth and STAT3 activity but enhanced miRNA342-3p expression. However, the miRNA342-3p mimic decreased Chi3L1 expression, cancer cell growth, and STAT3 activity. Moreover, a STAT3 inhibitor reduced Chi3L1 expression and cancer cell growth but enhanced miRNA342-3p expression. These data showed that lung tumor development was reduced through the decrease of Chi3L1 expression via the STAT3-dependent upregulation of miRNA342-3p. This study indicates that lung tumor development could be reduced in SwAPP AD mice.

Hydrogen peroxide in the reactions of cancer cells to cisplatin

BACKGROUND

Hydrogen peroxide (H₂O₂) is thought to be one of the key components involved in the responses of tumor cells to chemotherapy. The aim of this study was to reveal the pathways and the phases of cisplatin-induced cell death that are characterized by changes of H₂O₂ level.

METHODS

The genetically encoded cytosolic fluorescent sensor HyPer2 was used for flow cytometric analysis of the cisplatin-induced changes in H₂O₂ level in HeLa Kyoto cells. Using a vital dye and the apoptotic markers PE Annexin V or TMRE the pathways and stages of cell death were investigated simultaneously with HyPer2 response. The H₂O₂ level was studied separately in viable and early apoptotic cells after 12, 18, 24 h's incubation with cisplatin at several concentrations with or without the scavenger of reactive oxygen species NAC.

RESULTS

Cisplatin causes dose- and time-dependent increase of H₂O₂ level in TMRE-positive and PE Annexin V-negative cancer cells. The scavenging of ROS by NAC decreased the H₂O₂ level and restored cell viability.

CONCLUSION

Н₂О₂ generation begins in cells that have already lost mitochondrial membrane potential but have not yet externalized phosphatidylserine. Prevention of apoptosis by NAC confirmed the role of H₂O₂ in apoptosis induction.

GENERAL SIGNIFICANCE

This is the first time that the sensor HyPer2 has been used in parallel with apoptotic markers and vital dye to demonstrate the role of H₂O₂ in different stages and types of tumor cell death under chemotherapeutic action.

The Bcl-2 inhibitor venetoclax inhibits Nrf2 antioxidant pathway activation induced by hypomethylating agents in AML

Induction of reactive oxygen species (ROS), an important process for the cytotoxicity of various acute myeloid leukemia (AML) therapies including hypomethylating agents (HMAs), concurrently activates the NF-E2-related factor 2 (Nrf2) antioxidant response pathway which in turn results in induction of antioxidant enzymes that neutralize ROS. In this study, we demonstrated that Nrf2 inhibition is an additional mechanism responsible for the marked antileukemic activity in AML seen with the combination of HMAs and venetoclax (ABT-199). HMA and venetoclax combined treatment augmented mitochondrial ROS induction and apoptosis compared with treatment HMA alone. Treatment of AML cell lines as well as primary AML cells with venetoclax disrupted HMA decitabine-increased nuclear translocation of Nrf2 and induction of downstream antioxidant enzymes including heme oxygenase-1 and NADP-quinone oxidoreductase-1. Venetoclax treatment also leads to dissociation of B-cell lymphoma 2 from the Nrf2/Keap-1 complex and targets Nrf2 to ubiquitination and proteasomal degradation. Thus, our results here demonstrated an undiscovered mechanism underlying synergistic effect of decitabine and venetoclax in AML cells, elucidating for impressive results in antileukemic activity against AML in preclinical and early clinical studies by combined treatment of these drugs.

Evaluating protective and therapeutic effects of alpha-lipoic acid on cisplatin-induced ototoxicity

Cisplatin, a small platinum-containing molecule, is a widely used, highly effective anticancer drug. However, severe side effects have been found in cancer patients treated with cisplatin, including nephrotoxicity, neurotoxicity, and ototoxicity. These cisplatin-induced side effects can have a major impact on patient quality of life, including social development problems in pediatric patients that develop hearing loss. Previous studies have suggested that the major cause of cisplatin-induced ototoxicity is abnormal accumulation of reactive oxygen species (ROS) and oxidative stress. Alpha-lipoic acid (ALA), one of the most effective antioxidants, is known to be involved in the cellular antioxidant system and may have a protective effect on cisplatin-induced ototoxicity. However, the therapeutic effect of ALA on damaged hearing function and its detailed mechanism of action are not fully understood. This study focused on determining whether ALA has a potential as a protective and/or therapeutic agent for cisplatin-induced ototoxicity. Histological and physiological analyses were performed using cisplatin-treated mouse cochlea and HEI-OC1 culture cells in pre- and post-treatment with ALA in vitro and in vivo. We found that ALA contributes to protecting mitochondrial function by preventing ROS accumulation and inhibiting apoptotic cell death. Importantly, post-treatment with ALA consistently showed an almost equal restorative effect to pretreatment, in vitro and in vivo, supporting the possible use of ALA as a therapeutic agent for cisplatin-induced ototoxicity. This study is the first report on a strong therapeutic potential of ALA to rescue ototoxic hearing loss caused by cisplatin, and our data provide key evidence that ALA may act as a reducing agent for glutathione disulfide to increase glutathione levels on behalf of glutathione reductase. This result was consistent in both cultured cells and the mouse model, which improves the clinical value of ALA for therapy of cisplatin-induced ototoxicity.

Degradation of Bcl-2 by XIAP and ARTS Promotes Apoptosis

We describe a mechanism by which the anti-apoptotic B cell lymphoma 2 (Bcl-2) protein is downregulated to induce apoptosis. ARTS (Sept4_i2) is a tumor suppressor protein that promotes cell death through specifically antagonizing XIAP (X-linked inhibitor of apoptosis). ARTS and Bcl-2 reside at the outer mitochondrial membrane in living cells. Upon apoptotic induction, ARTS brings XIAP and Bcl-2 into a ternary complex, allowing XIAP to promote ubiquitylation and degradation of Bcl-2. ARTS binding to Bcl-2 involves the BH3 domain of Bcl-2. Lysine 17 in Bcl-2 serves as the main acceptor for ubiquitylation, and a Bcl-2 K17A mutant has increased stability and is more potent in protection against apoptosis. Bcl-2 ubiquitylation is reduced in both XIAP- and Sept4/ARTS-deficient MEFs, demonstrating that XIAP serves as an E3 ligase for Bcl-2 and that ARTS is essential for this process. Collectively, these results suggest a distinct model for the regulation of Bcl-2 by ARTS-mediated degradation.

Reactive oxygen species mediate heat stress-induced apoptosis via ERK dephosphorylation and Bcl-2 ubiquitination in human umbilical vein endothelial cells

Heat stress can induce the mitochondrial apoptotic pathway in HUVEC cells, indicating that apoptosis may be a prominent pathological feature of heat stroke, however, little is known about the precise mechani sms involved in it. In this study, we describe the apoptotic effect of intense heat stress on HUVEC cells and our investigation of its underlying mechanisms. Treatment of cells with intense heat stress induced production of reactive oxygen species (ROS) and a concomitant increase in activation of the mitochondrial apoptotic pathway. Furthermore, by over-expression of MnSOD and GPx in cells, we show that ROS, and especially superoxide, is the primary oxidative species induced by intense heat stress and responsible for cell death. In addition, we explored the mechanism by which superoxide regulates the apoptotic effect of intense heat stress, and found that it involved Bcl-2 down-regulation through ubiquitin - proteasomal degradation. Superoxide production also led to Bcl-2 dephosphorylation through inactivation of MAP kinase ERK1/2, which promoted Bcl-2 ubiquitination. Taken together, these findings describe a novel pathway downstream of heat stress-induced apoptosis in HUVEC cells, and provide new insight into the process of redox-mediated down-regulation of Bcl-2 and apoptosis induction. These results could be important in the understanding of pathogenesis of heat stroke and for the development of preventive and treatment measures, both of which are currently lacking.

Presenilin Mutation Suppresses Lung Tumorigenesis via Inhibition of Peroxiredoxin 6 Activity and Expression

Some epidemiological studies suggest an inverse correlation between cancer incidence and Alzheimer's disease (AD). In this study, we demonstrated experimental evidences for this inverse relationship. In the co-expression network analysis using the microarray data and GEO profile of gene expression omnibus data analysis, we showed that the expression of peroxiredoxin 6 (PRDX6), a tumor promoting protein was significantly increased in human squamous lung cancer, but decreased in mutant presenilin 2 (PS2) containing AD patient. We also found in animal model that mutant PS2 transgenic mice displayed a reduced incidence of spontaneous and carcinogen-induced lung tumor development compared to wildtype transgenic mice. Agreed with network and GEO profile study, we also revealed that significantly reduced expression of PRDX6 and activity of iPLA2 in these animal models. PS2 mutations increased their interaction with PRDX6, thereby increasing iPLA2 cleavage via increased γ-secretase leading to loss of PRDX6 activity. However, knockdown or inhibition of γ-secretase abolished the inhibitory effect of mutant PSs. Moreover, PS2 mutant skin fibroblasts derived from patients with AD showed diminished iPLA2 activity by the elevated γ-secretase activity. Thus, the present data suggest that PS2 mutations suppress lung tumor development by inhibiting the iPLA2 activity of PRDX6 via a γ-secretase cleavage mechanism and may explain the inverse relationship between cancer and AD incidence.

α-Lipoic acid sensitizes lung cancer cells to chemotherapeutic agents and anoikis via integrin β1/β3 downregulation

Chemotherapeutic failure and metastasis are the main causes of high mortality rate in lung cancer. Alteration of cellular redox status in response to endogenous stimuli or exogenous compounds has a significant impact on cell signaling and behavior. Herein we divulge for the first time that lung cancer cells exposed to α-lipoic acid (LA) resulted in a higher level of cellular superoxide anion (O2·-) and hydrogen peroxide (H2O2), and such an increase of the specific reactive oxygen species (ROS) downregulated integrin β1 and β3, the integrins known for potentiating aggressive behavior and metastasis. The LA-treated cells exhibited significant decrease in their abilities to survive in detached condition and grow in anchorage-independent soft agar assay. Furthermore, LA sensitized the cells to cisplatin, etoposide and paclitaxel-induced apoptosis. For underlying mechanism, we found that the treatment of the cells with LA significantly decreased integrin β1 and β3, while had no effect on integrin α5 and αv. Interestingly, survival protein p-AKT and anti-apoptotic protein Bcl-2 were reduced in an association to such integrin modulations. Using ROS probes and selective anti-oxidants, we have shown that H2O2 and O2·- induced by LA are key players for the decrease of β1 and β3 integrins, respectively. These findings indicate a novel effect of LA as well as specific ROS, O2·- and H2O2 in integrin regulation, anoikis and chemotherapeutic sensitizations.

Antiproliferative activity of the isoindigo 5'-Br in HL-60 cells is mediated by apoptosis, dysregulation of mitochondrial functions and arresting cell cycle at G0/G1 phase

Our new compound, 5'-Br [(E)-1-(5'-bromo-2'-oxoindolin-3'-ylidene)-6-ethyl-2,3,6,9-tetrahydro-2,9-dioxo-1H-pyrrolo[3,2-f]quinoline-8-carboxylic acid], had shown strong, selective antiproliferative activity against different cancer cell lines. Here, we aim to comprehensively characterize the mechanisms associated with its cytotoxicity in the human promyelocytic leukemia HL-60 cells. We focused at studying the involvement of apoptotic pathway and cell cycle effects. 5'-Br significantly inhibited proliferation by inducing caspase-dependent apoptosis. Involvement of caspase independent mechanism is also possible due to observed inability of z-VAD-FMK to rescue apoptotic cells. 5'-Br was found to trigger intrinsic apoptotic pathway as indicated by depolarization of the mitochondrial inner membrane, decreased level of cellular ATP, modulated expression and phosphorylation of Bcl-2 leading to loss of its association with Bax, and increased release of cytochrome c. 5'-Br treated cells were found arrested at G0/G1 phase with modulation in protein levels of cyclins, dependent kinases and their inhibitors. Expression and enzymatic activity of CDK2 and CDK4 was found inhibited. Retinoblastoma protein (Rb) phosphorylation was also inhibited whereas p21 protein levels were increased. These results suggest that the antiproliferative mechanisms of action of 5'-Br could involve apoptotic pathways, dysregulation of mitochondrial functions and disruption of cell cycle checkpoint.

PRDX6 promotes tumor development via the JAK2/STAT3 pathway in a urethane-induced lung tumor model

Peroxiredoxin 6 (PRDX6) is a bifunctional protein with both glutathione peroxidase (GPx) and iPLA2 activities. Even though several pathophysiological functions have been studied, the definitive role of PRDX6 in tumor growth is not clear. Here, we compared carcinogen-induced tumor growth in PRDX6-transgenic (Tg) mice and non-Tg mice to evaluate the roles of PRDX6 in lung tumor development. Urethane (1g/kg)-induced tumor incidence in PRDX6-Tg mice was significantly higher compared to non-Tg mice. In the tumors of PRDX6-Tg mice, the activation of JAK2/STAT3 and STAT3 DNA binding were also increased, accompanied by increased GPx and iPLA2 activities. PRDX6 was colocalized with JAK2 in tumor tissues and lung cancer cells and also showed physical interaction with JAK2. We found that increasing levels of PRDX6 increase the activation of the JAK2/STAT3 pathway. Furthermore, PRDX6-Tg mice showed altered cytokine levels in the tumors, especially leading to increased CCL5 levels. We validated that the activation of JAK2 was also decreased in lung tumors of CCR5(-/-) mice, and CCL5 increased the JAK2/STAT3 pathway in the lung cancer cells. Thus, our findings suggest that PRDX6 promotes lung tumor development via its mediated and CCL5-associated activation of the JAK2/STAT3 pathway.

MiR-16 targets Bcl-2 in paclitaxel-resistant lung cancer cells and overexpression of miR-16 along with miR-17 causes unprecedented sensitivity by simultaneously modulating autophagy and apoptosis

Non-small cell lung cancer is one of the most aggressive cancers as per as the mortality and occurrence is concerned. Paclitaxel based chemotherapeutic regimes are now used as an important option for the treatment of lung cancer. However, resistance of lung cancer cells to paclitaxel continues to be a major clinical problem nowadays. Despite impressive initial clinical response, most of the patients eventually develop some degree of paclitaxel resistance in the course of treatment. Previously, utilizing miRNA arrays we reported that downregulation of miR-17 is at least partly involved in the development of paclitaxel resistance in lung cancer cells by modulating Beclin-1 expression [1]. In this study, we showed that miR-16 was also significantly downregulated in paclitaxel resistant lung cancer cells. We demonstrated that anti-apoptotic protein Bcl-2 was directly targeted miR-16 in paclitaxel resistant lung cancer cells. Moreover, in this report we showed that the combined overexpression of miR-16 and miR-17 and subsequent paclitaxel treatment greatly sensitized paclitaxel resistant lung cancer cells to paclitaxel by inducing apoptosis via caspase-3 mediated pathway. Combined overexpression of miR-16 and miR-17 greatly reduced Beclin-1 and Bcl-2 expressions respectively. Our results indicated that though miR-17 and miR-16 had no common target, both miR-16 and miR-17 jointly played roles in the development of paclitaxel resistance in lung cancer. miR-17 overexpression reduced cytoprotective autophagy by targeting Beclin-1, whereas overexpression of miR-16 potentiated paclitaxel induced apoptotic cell death by inhibiting anti-apoptotic protein Bcl-2.

Analysis of BIM (BCL-2 like 11 gene) deletion polymorphism in Chinese non-small cell lung cancer patients

BACKGROUND

Drug resistance significantly weakens the efficacy of cancer treatment, and the BIM (also known as the BCL2L11 gene) deletion polymorphism has been identified as a potential biomarker for drug resistance. In this retrospective study, we included a total of 290 patients with advanced non-small cell lung cancer (NSCLC) who received treatment with epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) and chemotherapy.

METHODS

The BIM deletion polymorphism of each patient was detected by polymerase chain reaction. EGFR mutations were detected by denaturing high-performance liquid chromatography methods and the amplification refractory mutation system.

RESULTS

The BIM deletion polymorphism was detected in 45/290 (15.5%) Chinese NSCLC patients. No associations were observed between the BIM deletion and clinic-pathologic characteristics of patients. The BIM deletion polymorphism was predictive of shorter progression-free survival in Chinese patients with EGFR-mutant adenocarcinoma and who were treated with EGFR-TKIs (7.30 vs. 9.53 months, P = 0.034). Additionally, we found that the BIM deletion polymorphism was an effective predictor of short progression-free survival in individuals with EGFR-mutant NSCLC and treated with chemotherapy containing pemetrexed (3.32 vs. 5.30, P = 0.012) or second-/beyond-line chemotherapy containing taxanes (1.53 vs. 2.61 months, P = 0.025). The BIM deletion was not correlated with overall survival.

CONCLUSION

The BIM deletion polymorphism occurs in 15.5% of Chinese NSCLC patients, and is a biomarker for resistance to TKIs and chemotherapy. However, BIM deletion was not a decisive factor in overall survival.

Loss of presenilin 2 is associated with increased iPLA2 activity and lung tumor development

Presenilins are the enzymatic components of γ-secretase complex that cleaves amyloid precursor protein, Notch and β-catenin, which has critical roles in the development of Alzheimer's disease and cancer cell growth. Therefore, in the present study, we studied the effects and mechanisms of PS2 knockout on lung cancer development and possible mechanisms as a key regulator of lung tumor development. We compared carcinogen-induced tumor growth between PS2 knockout mice and wild-type mice. PS2 knockout mice showed increased urethane (1 mg/g)-induced lung tumor incidence when compared with that of wild-type mice with decreased activity of γ-secretase in the lung tumor tissues. Consequently, iPLA2 activities in lung tumor tissues of PS2 knockout mice were much higher than in tumor tissues of wild-type mice. Furthermore, knockdown of PS2 using PS2 siRNA decreased γ-secretase activity with increased iPLA2 activity in the lung cancer cells (A549 and NCI-H460), leading to increased lung cancer cell growth. PS2 knockout mice and PS2 knockdown lung cancer cells showed increased DNA-binding activities of nuclear factor kappa-beta, signal transducer and activator of transcription 3 (STAT3) and AP-1 which are critical transcriptional factors of iPLA2 than those of PS2 wild-type mice and control lung cancer cells. Taken together, these results suggest that the loss of PS2 could have a critical role in lung tumor development through the upregulation of iPLA2 activity by reducing γ-secretase.

Anti-cancer effect of thiacremonone through down regulation of peroxiredoxin 6

Thiacremonone (2, 4-dihydroxy-2, 5-dimethyl-thiophene-3-one) is an antioxidant substance as a novel sulfur compound generated from High-Temperature-High-Pressure-treated garlic. Peroxiredoxin 6 (PRDX6) is a member of peroxidases, and has glutathione peroxidase and calcium-independent phospholipase A2 (iPLA2) activities. Several studies have demonstrated that PRDX6 stimulates lung cancer cell growth via an increase of glutathione peroxidase activity. A docking model study and pull down assay showed that thiacremonone completely fits on the active site (cys-47) of glutathione peroxidase of PRDX6 and interacts with PRDX6. Thus, we investigated whether thiacremonone inhibits cell growth by blocking glutathione peroxidase of PRDX6 in the human lung cancer cells, A549 and NCI-H460. Thiacremonone (0-50 μg/ml) inhibited lung cancer cell growth in a concentration dependent manner through induction of apoptotic cell death accompanied by induction of cleaved caspase-3, -8, -9, Bax, p21 and p53, but decrease of xIAP, cIAP and Bcl2 expression. Thiacremonone further inhibited glutathione peroxidase activity in lung cancer cells. However, the cell growth inhibitory effect of thiacremonone was not observed in the lung cancer cells transfected with mutant PRDX6 (C47S) and in the presence of dithiothreitol and glutathione. In an allograft in vivo model, thiacremonone (30 mg/kg) also inhibited tumor growth accompanied with the reduction of PRDX6 expression and glutathione peroxidase activity, but increased expression of cleaved caspase-3, -8, -9, Bax, p21 and p53. These data indicate that thiacremonone inhibits tumor growth via inhibition of glutathione peroxidase activity of PRDX6 through interaction. These data suggest that thiacremonone may have potentially beneficial effects in lung cancer.

Replacement of a quinone by a 5-O-acetylhydroquinone abolishes the accidental necrosis inducing effect while preserving the apoptosis-inducing effect of renieramycin M on lung cancer cells

Renieramycin M (1), a bistetrahydroisoquinolinequinone alkaloid isolated from the marine sponge Xestospongia sp., has been reported to possess promising anticancer effects. However, its accidental necrosis inducing effect has limited further development due to concerns of unwanted toxicity. The presence of two quinone moieties in its structure was demonstrated to induce accidental necrosis and increase reactive oxygen species (ROS) levels. Therefore, one quinone of 1 was modified to produce the 5-O-acetylated hydroquinone derivative (2), and 2 dramatically reduced the accidental necrosis inducing effect while preserving the apoptosis-inducing effect of parent 1 on lung cancer H23 cells. Addition of the antioxidant N-acetylcysteine suppressed the accidental necrosis mediated by 1, suggesting that its accidental necrosis inducing effect was ROS-dependent. The fluorescent probe dihydroethidium revealed that the accidental necrosis mediated by 1 was due to its ability to generate intracellular superoxide anions. Interestingly, the remaining quinone in 2 was required for its cytotoxicity, as the 5,8,15,18-O-tetraacetylated bishydroquinone derivative (3) exhibited weak cytotoxicity compared to 1 and 2. The present study demonstrates a simple way to eliminate the undesired accidental necrosis inducing effect of substances that may be developed as improved anticancer drug candidates.

Lung tumor growth-promoting function of peroxiredoxin 6

This study compared lung tumor growth in PRDX6-overexpressing transgenic (Tg) mice and normal mice. These mice expressed elevated levels of PRDX6 mRNA and protein in multiple tissues. In vivo, Tg mice displayed a greater increase in the growth of lung tumor compared with normal mice. Glutathione peroxidase and calcium-independent phospholipase 2 (iPLA2) activities in tumor tissues of Tg mice were much higher than in tumor tissues of normal mice. Higher tumor growth in PRDX6-overexpressing Tg mice was associated with an increase in activating protein-1 (AP-1) DNA-binding activity. Moreover, expression of proliferating cell nuclear antigen, Ki67, vascular endothelial growth factor, c-Jun, c-Fos, metalloproteinase-9, cyclin-dependent kinases, and cyclins was much higher in the tumor tissues of PRDX6-overexpressing Tg mice than in tumor tissues of normal mice. However, the expression of apoptotic regulatory proteins including caspase-3 and Bax was slightly less in the tumor tissues of normal mice. In tumor tissues of PRDX6-overexpressing Tg mice, activation of mitogen-activated protein kinases (MAPKs) was much higher than in normal mice. In cultured lung cancer cells, PRDX6 siRNA suppressed glutathione peroxidase and iPLA2 activities and cancer cell growth, but the enforced overexpression of PRDX6 increased cancer cell growth associated with their increased activities. In vitro, among the tested MAPK inhibitors, c-Jun NH2-terminal kinase (JNK) inhibitor clearly suppressed the growth of lung cancer cells and AP-1 DNA binding, glutathione peroxidase activity, and iPLA2 activity in normal and PRDX6-overexpressing lung cancer cells. These data indicate that overexpression of PRDX6 promotes lung tumor growth via increased glutathione peroxidase and iPLA2 activities through the upregulation of the AP-1 and JNK pathways.

Regulation of apoptosis by Bcl-2 cysteine oxidation in human lung epithelial cells

Bcl-2 interacts with ERK to suppress apoptosis. Hydrogen peroxide disrupts the interaction through Bcl-2 cysteine oxidation, which promotes apoptosis. These findings provide a novel redox regulatory mechanism that controls apoptosis via Bcl-2 cysteine oxidation, which could aid in the understanding of pathogenesis under oxidative stress conditions.

Hydrogen peroxide is a key mediator of oxidative stress known to be important in various cellular processes, including apoptosis. B-cell lymphoma-2 (Bcl-2) is an oxidative stress–responsive protein and a key regulator of apoptosis; however, the underlying mechanisms of oxidative regulation of Bcl-2 are not well understood. The present study investigates the direct effect of H₂O₂ on Bcl-2 cysteine oxidation as a potential mechanism of apoptosis regulation. Exposure of human lung epithelial cells to H₂O₂ induces apoptosis concomitant with cysteine oxidation and down-regulation of Bcl-2. Inhibition of Bcl-2 oxidation by antioxidants or by site-directed mutagenesis of Bcl-2 at Cys-158 and Cys-229 abrogates the effects of H₂O₂ on Bcl-2 and apoptosis. Immunoprecipitation and confocal microscopic studies show that Bcl-2 interacts with mitogen-activated protein kinase (extracellular signal-regulated kinase 1/2 [ERK1/2]) to suppress apoptosis and that this interaction is modulated by cysteine oxidation of Bcl-2. The H₂O₂-induced Bcl-2 cysteine oxidation interferes with Bcl-2 and ERK1/2 interaction. Mutation of the cysteine residues inhibits the disruption of Bcl-2–ERK complex, as well as the induction of apoptosis by H₂O₂. Taken together, these results demonstrate the critical role of Bcl-2 cysteine oxidation in the regulation of apoptosis through ERK signaling. This new finding reveals crucial redox regulatory mechanisms that control the antiapoptotic function of Bcl-2.

Pristimerin Induces Apoptosis in Prostate Cancer Cells by Down-regulating Bcl-2 through ROS-dependent Ubiquitin-proteasomal Degradation Pathway

Pristimerin is a quinonemethide triterpenoid with the potential of a promising anticancer agent. Pristimerin (PM) has shown anticancer activity against a range of cancer cell lines, but its activity for prostate cancer has not been adequately investigated. In the present study we have examined the underlying mechanisms of the apoptotic response of the hormone-sensitive (LNCaP) and hormone-refractory (PC-3) prostate cancer cell lines to PM. Treatment with PM induced apoptosis in both cell lines as characterized by increased annexin V-binding and cleavage of PARP-1 and procaspases-3 and -9. It also induced mitochondrial depolarization, cytochrome c release from mitochondria and generation of reactive oxygen species (ROS). Response to PM is regulated by Bcl-2 since it down-regulated Bcl-2 expression and overexpression of Bcl-2 rendered prostate cancer cells resistant to PM. ROS plays a role in down-regulation of Bcl-2, since treatment with PM in the presence of various ROS modulators, e.g., n-acetylcysteine (NAC), a general purpose antioxidant; diphenylene iodonium (DPI), a NADPH inhibitor; rotenone (ROT), a mitochondrial electron transport chain interrupter rotenone or MnTBAP, a O₂ scavenger, attenuated the down-regulation of Bcl-2. Furthermore, ROS is also involved in the ubiquitination and proteasomal degradation of Bcl-2 as both of these events were blocked by O ₂^- scavenger MnTBAP. Thus, pristimerin induces apoptosis in prostate cancer cells predominately through the mitochondrial apoptotic pathway by inhibiting antiapoptic Bcl-2 through a ROS-dependent ubiquitin-proteasomal degradation pathway.

Ouabain downregulates Mcl-1 and sensitizes lung cancer cells to TRAIL-induced apoptosis

Resistance to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a prerequisite for cancer progression, and TRAIL resistance is prevalent in lung cancer. Ouabain, a recently identified human hormone, has shown therapeutic promise by potentiating the apoptotic response of metastatic lung cancer cells to TRAIL. Nontoxic concentrations of ouabain are shown to increase caspase-3 activation, poly(ADP-ribose) polymerase (PARP) cleavage, and apoptosis of H292 cells in response to TRAIL. While ouabain had a minimal effect on c-FLIP, Bcl-2, and Bax levels, we show that it possesses an ability to downregulate the antiapoptotic Mcl-1 protein. The present study also reveals that the sensitizing effect of ouabain is associated with its ability to generate reactive oxygen species (ROS), and hydrogen peroxide is identified as the principle ROS triggering proteasomal Mcl-1 degradation. In summary, our results indicate a novel function for ouabain in TRAIL-mediated cancer cell death through Mcl-1 downregulation, thereby providing new insight into a potential lung cancer treatment as well as a better understanding of the physiological activity of ouabain.

Wogonin potentiates cisplatin-induced cancer cell apoptosis through accumulation of intracellular reactive oxygen species

Chemoresistance to cisplatin is a major limitation of cisplatin-based chemotherapy in the clinic. The combination of cisplatin with other agents has been recognized as a promising strategy to overcome cisplatin resistance. Previous studies have shown that wogonin (5,7-dihydroxy-8-methoxyflavone), a flavonoid isolated from the root of the medicinal herb Scutellaria baicalensis Georgi, sensitizes cancer cells to chemotheraputics such as etoposide, adriamycin, tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and TNF. However, the effect of wogonin on cisplatin-induced cytotoxicity has not been previously reported. In this study, the non-small cell lung cancer cell line A549 and the cervical cancer cell line HeLa were treated with wogonin or cisplatin individually or in combination. It was found for the first time that wogonin is able to sensitize cisplatin-induced apoptosis in both A549 cells and HeLa cells as indicated by the potentiation of activation of caspase-3, and cleavage of the caspase-3 substrate PARP in wogonin and cisplatin co-treated cells. Importantly, wogonin robustly induced H2O2 accumulation in these cells, which substantially contributes to the sensitization of cisplatin cytotoxicity by wogonin, as two reactive oxygen species scavengers, butylated hydroxyanisole (BHA) and N-acetyl-L-cysteine (NAC), significantly suppressed the potentiated cytotoxicity caused by wogonin and cisplatin co-treatment. The results from this study provide important new evidence supporting the potential use of wogonin as a cisplatin sensitizer for cancer therapy.

Expression of CA125 and cisplatin susceptibility of pleural effusion-derived human lung cancer cells from a Thai patient

Advances in understanding lung cancer biology and tumor markers aid clinicians in managing the disease. Cancer-associated antigen (CA)125 has garnered increasing attention in lung cancer research and may benefit the treatment and follow-up of this type of cancer. In Thai lung cancer patients, knowledge regarding ethnic differences in cancer cell biology is largely absent. We generated lung cancer cells from the pleural effusion fluids of a Thai patient and designated these as P1 cells. P1 cells were assessed for growth rate, response to chemotherapy, and the presence of tumor markers, in particular CA125 expression. Results of immunofluorescence indicated that P1 cells exhibited strong expression levels of CA125, comparable to that of established H460 lung cancer cells. Furthermore, P1 cells were analyzed for the expression of additional markers. Results revealed that H460 cells exhibited strong immunofluorescent signals from cytokeratin-19 fragments (CYFRA 21-1) and squamous cell carcinoma antigen (SCCA) while P1 presented only CYFRA 21-1 signals. We also found evidence of relative cisplatin resistance in P1 compared to the susceptibility level of established lung cancer cells. Thus, the results and methodology described in this study may aid the development of lung cancer diagnostic and therapeutic approaches and, in particular, advance understanding of ethnic differences.

Mitochondrial superoxide mediates doxorubicin-induced keratinocyte apoptosis through oxidative modification of ERK and Bcl-2 ubiquitination

Massive apoptosis of keratinocytes has been implicated in the pathogenesis of chemotherapy-induced skin toxicities, but the underlying mechanisms of action are not well understood. The present study investigated the apoptotic effect of doxorubicin (DOX) on HaCaT keratinocytes and determined the underlying mechanisms. Treatment of the cells with DOX induced reactive oxygen species (ROS) generation and a concomitant increase in apoptotic cell death through the mitochondrial death pathway independent of p53. Electron spin resonance and flow cytometry studies showed that superoxide is the primary oxidative species induced by DOX and responsible for the death inducing effect. Ectopic expression of mitochondrial superoxide scavenging enzyme (MnSOD) or treatment with MnSOD mimetic (MnTBAP) inhibited DOX-induced superoxide generation and apoptosis. The mechanism by which superoxide mediates the apoptotic effect of DOX was shown to involve downregulation of Bcl-2 through ubiquitin-proteasomal degradation. Superoxide induces dephosphorylation of Bcl-2 through MAP kinase ERK1/2 inactivation, which promotes ubiquitination of Bcl-2. We also provide evidence for the oxidative modification of ERK1/2 through cysteine sulfenic acid formation. These findings indicate a novel pathway for redox regulation of apoptosis regulatory proteins, which could be important in the understanding of chemotherapy-induced toxicities and development of preventive treatment strategies which are currently lacking.

Overexpression of 5-lipoxygenase increases the neuronal vulnerability of PC12 cells to Aβ₄₂

5-Lipoxygenase (5-LOX), which is believed to be a major source of oxidative stress, participates in somatostatin-receptor transmembrane signaling in the central nervous system. We used the Tet-On inducible expression system in PC12 cells to obtain cell lines with reproducible, stable 5-LOX expression levels to study its function. Cell apoptosis rates induced by Aβ(42) were determined using an apo-BrdDU kit. Lipid peroxide, antioxidant enzyme, and caspase-3 activities were evaluated with respective commercial kits. The expression of 5-LOX, bcl-2, and bax were detected by immunoblotting. A subclone of PC18 with Tet-On inducible expression of 5-LOX was selected from PC12 transfectants. Expression of 5-LOX had no significant inhibitory effect on the cell viability of the PC18 clone. In contrast, compared with the control group, the cell viability of clone PC18 was significantly reduced after the induction of 5-LOX during Aβ exposure. The differences in cell viability before and after the induction of 5-LOX during Aβ insult were significantly offset by AA861. Overexpression of 5-LOX only slightly improved the activities of superoxide dismutase (SOD). The levels of intracellular peroxides, SOD and caspase-3 activity, and Bax expression were significantly upregulated, and the levels of glutathione peroxidase and catalase were downregulated correspondingly in clone PC18 during Aβ exposure. These results indicate that constitutive expression of 5-LOX is not detrimental per se, but overexpression of 5-LOX may become problematic during Aβ exposure.

Protective effect of Glycine max and Chrysanthemum indicum extracts against cisplatin-induced renal epithelial cell death

Although cisplatin is one of the most efficient chemotherapeutic agents for the treatment of solid tumors, frequently observed nephrotoxicity has limited its use in several patients.

MATERIALS AND METHODS

The protective effect of Glycine max (GM) and Chrysanthemum indicum (CM) extracts on cisplatin-induced apoptosis in human proximal tubular HK-2 cells was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), Hoechst 33342, and propidium iodide assays. Reactive oxygen species (ROS) were determined by flow cytometry with 2,7-dichlorofluorescein diacetate (DCFH(2)-DA).

RESULTS

Cisplatin-induced renal cell toxicity through the induction of hydrogen peroxide (H(2)O(2)) and hydroxyl radical (OH(•-)). CM extract protected cisplatin-induced apoptosis by its anti-oxidant activity against H(2)O(2) and OH(•-), while GM extract scavenged only H(2)O(2). Furthermore, GM and CM extracts protect renal cells without significant interfering effect on cisplatin toxicity in lung cancer H460 and melanoma G361 cells.

CONCLUSION

GM and CM extracts exhibited a promising protective effect on cisplatin-induced nephrotoxicity which could benefit the development for nephroprotective approaches.

Hydroxyl radical mediates cisplatin-induced apoptosis in human hair follicle dermal papilla cells and keratinocytes through Bcl-2-dependent mechanism

Induction of massive apoptosis of hair follicle cells by chemotherapy has been implicated in the pathogenesis of chemotherapy-induced alopecia (CIA), but the underlying mechanisms of regulation are not well understood. The present study investigated the apoptotic effect of cisplatin in human hair follicle dermal papilla cells and HaCaT keratinocytes, and determined the identity and role of specific reactive oxygen species (ROS) involved in the process. Treatment of the cells with cisplatin induced ROS generation and a parallel increase in caspase activation and apoptotic cell death. Inhibition of ROS generation by antioxidants inhibited the apoptotic effect of cisplatin, indicating the role of ROS in the process. Studies using specific ROS scavengers further showed that hydroxyl radical, but not hydrogen peroxide or superoxide anion, is the primary oxidative species responsible for the apoptotic effect of cisplatin. Electron spin resonance studies confirmed the formation of hydroxyl radicals induced by cisplatin. The mechanism by which hydroxyl radical mediates the apoptotic effect of cisplatin was shown to involve down-regulation of the anti-apoptotic protein Bcl-2 through ubiquitin-proteasomal degradation. Bcl-2 was also shown to have a negative regulatory role on hydroxyl radical. Together, our results indicate an essential role of hydroxyl radical in cisplatin-induced cell death of hair follicle cells through Bcl-2 regulation. Since CIA is a major side effect of cisplatin and many other chemotherapeutic agents with no known effective treatments, the knowledge gained from this study could be useful in the design of preventive treatment strategies for CIA through localized therapy without compromising the chemotherapy efficacy.

Modulation of Bcl-2-related protein expression in pancreatic beta cells by pro-inflammatory cytokines and its dependence on the antioxidative defense status

Pro-inflammatory cytokines are key mediators in the selective and progressive destruction of insulin-producing beta cells during type 1 diabetes development. However, the mechanisms of cytokine-induced beta cell apoptosis are not fully understood. This study demonstrates that pro-inflammatory cytokines strongly modified the expression of the anti-apoptotic protein Bcl-2 and the pro-apoptotic BH3-only proteins Bad, Bim, and Bid in primary rat islets and insulin-producing RINm5F cells. Overexpression of mitochondrially located catalase (MitoCatalase) specifically increased basal Bcl-2 and decreased basal Bax expression, suppressed cytokine-mediated reduction of Bcl-2, and thereby prevented the release of cytochrome c, Smac/DIABLO and the activation of caspase-9 and -3. Thus, cytokine-mediated decrease of Bcl-2 expression and the sequentially changed Bax/Bcl-2 ratio are responsible for the release of pro-apoptotic mitochondrial factors, activation of caspase-9, and ultimately caspase-3. These results indicate that activation of the intrinsic/mitochondrial apoptosis pathway is essential for cytokine-induced beta cell death and the mitochondrial generation of reactive oxygen species, in particular mitochondrial hydrogen peroxide, differentially regulates the Bax/Bcl-2 ratio.

Cisplatin triggers atrophy of skeletal C2C12 myotubes via impairment of Akt signalling pathway and subsequent increment activity of proteasome and autophagy systems

Cisplatin (cisPt) is an antineoplastic drug which causes an array of adverse effects on different organs and tissues, including skeletal muscle. In this work we show that cisPt behaves as a potent trigger to activate protein hypercatabolism in skeletal C2C12 myotubes. Within 24h of 50 μM cisPt administration, C2C12 myotubes displayed unchanged cell viability but showed a subset of hallmark signs typically recognized during atrophy, including severe reduction in body size, repression of Akt phosphorylation, transcriptional up-regulation of atrophy-related genes, such as atrogin-1, gabarap, beclin-1 and bnip-3, and loss of myogenic markers. As a consequence, proteasomal activity and formation of autophagosomes were remarkably increased in cisPt-treated myotubes, but forced stimulation of Akt pathway, as obtained through insulin administration or delivery of a constitutively activated Akt form, was sufficient to counter the cisPt-induced protein breakdown, leading to rescue of atrophic size. Overall, these results indicate that cisPt induces atrophy of C2C12 myotubes via activation of proteasome and autophagy systems, suggesting that the Akt pathway represents one sensitive target of cisPt molecular action in skeletal muscle.

Tumor and host factors that may limit efficacy of chemotherapy in non-small cell and small cell lung cancer

While chemotherapy provides useful palliation, advanced lung cancer remains incurable since those tumors that are initially sensitive to therapy rapidly develop acquired resistance. Resistance may arise from impaired drug delivery, extracellular factors, decreased drug uptake into tumor cells, increased drug efflux, drug inactivation by detoxifying factors, decreased drug activation or binding to target, altered target, increased damage repair, tolerance of damage, decreased proapoptotic factors, increased antiapoptotic factors, or altered cell cycling or transcription factors. Factors for which there is now substantial clinical evidence of a link to small cell lung cancer (SCLC) resistance to chemotherapy include MRP (for platinum-based combination chemotherapy) and MDR1/P-gp (for non-platinum agents). SPECT MIBI and Tc-TF scanning appears to predict chemotherapy benefit in SCLC. In non-small cell lung cancer (NSCLC), the strongest clinical evidence is for taxane resistance with elevated expression or mutation of class III beta-tubulin (and possibly alpha tubulin), platinum resistance and expression of ERCC1 or BCRP, gemcitabine resistance and RRM1 expression, and resistance to several agents and COX-2 expression (although COX-2 inhibitors have had minimal impact on drug efficacy clinically). Tumors expressing high BRCA1 may have increased resistance to platinums but increased sensitivity to taxanes. Limited early clinical data suggest that chemotherapy resistance in NSCLC may also be increased with decreased expression of cyclin B1 or of Eg5, or with increased expression of ICAM, matrilysin, osteopontin, DDH, survivin, PCDGF, caveolin-1, p21WAF1/CIP1, or 14-3-3sigma, and that IGF-1R inhibitors may increase efficacy of chemotherapy, particularly in squamous cell carcinomas. Equivocal data (with some positive studies but other negative studies) suggest that NSCLC tumors with some EGFR mutations may have increased sensitivity to chemotherapy, while K-ras mutations and expression of GST-pi, RB or p27kip1 may possibly confer resistance. While limited clinical data suggest that p53 mutations are associated with resistance to platinum-based therapies in NSCLC, data on p53 IHC positivity are equivocal. To date, resistance-modulating strategies have generally not proven clinically useful in lung cancer, although small randomized trials suggest a modest benefit of verapamil and related agents in NSCLC.

Global analysis of CpG methylation reveals epigenetic control of the radiosensitivity in lung cancer cell lines

Epigenetic regulation by CpG methylation has an important role in tumorigenesis as well as in the response to cancer therapy. To analyze the mechanism of epigenetic control of radiosensitivity, the CpG methylation profiles of radiosensitive H460 and radioresistant H1299 human non-small cell lung cancer (NSCLC) cell lines were analyzed using microarray profiling. These analyses revealed 1091 differentially methylated genes (DMG) (absolute difference of mean beta-values, |Deltabeta |>0.5), including genes involved in cell adhesion, cell communication, signal transduction and transcriptional regulation. Among the 747 genes hypermethylated in radioresistant H1299 cells, CpG methylation of SERPINB5 and S100A6 in radioresistant H1299 cells was confirmed by methylation-specific PCR. Reverse transcriptase-PCR showed higher expression of these two genes in radiosensitive H460 cells compared with radioresistant H1299 cells. Downregulation of SERPINB5 or S100A6 by small interfering RNA in H460 cells increased the resistance of these cells to ionizing radiation. In contrast, promoter CpG sites of 344 genes, including CAT and BNC1, were hypomethylated in radioresistant H1299 cells. Suppression of CAT or BNC1 mRNA expression in H1299 cells also reduced the resistance of these cells to ionizing radiation. Thus, we identified DMGs by genome-wide CpG methylation profiling in two NSCLC cell lines with different responses to ionizing radiation, and our data indicated that these differences may be critical for epigenetic regulation of radiosensitivity in lung cancer cells.

Differentiating and apoptotic dose-dependent effects in (-)-alpha-bisabolol-treated human endothelial cells

The effect on angiogenesis of (-)-alpha-bisabolol [(-)-6-methyl-2-(4-methyl-3-cyclohexen-1-yl)-5-hepten-2-ol] (1), a widely distributed plant sesquiterpene alcohol, was investigated for the first time. Human endothelial cells treated with 1 were analyzed for their ability to differentiate and organize in microvessels and for their sensitivity to this compound in terms of cytotoxicity and cell growth inhibition. Within 24 h of the treatment with 5 microM 1, cells underwent massive death. Apoptosis induction was responsible for cytotoxicity triggered by 1 as revealed by the release of cytochrome c from the mitochondria, reduction of the Bcl-2/Bax ratio, and caspase 3 activation. At a lower, non-apoptotic concentration (0.25 microM), 1 showed a differentiating effect resulting in growth inhibition, invasiveness reduction, and tubule stabilization.

RACK-1 overexpression protects against goniothalamin-induced cell death

Goniothalamin, a styryllactone, has been shown to induce cytotoxicity via apoptosis in several tumor cell lines. In this study, we have examined the potential role of several genes, which were stably transfected into T-cell lines and which regulate apoptosis in different ways, on goniothalamin-induced cell death. Overexpression of full-length receptor for activated protein C-kinase 1 (RACK-1) and pc3n3, which up-regulates endogenous RACK-1, in both Jurkat and W7.2 T cells resulted in inhibition of goniothalamin-induced cell death as assessed by MTT and clonogenic assays. However, overexpression of rFau (antisense sequence to Finkel-Biskis-Reilly murine sarcoma virus-associated ubiquitously expressed gene) in W7.2 cells did not confer resistance to goniothalamin-induced cell death. Etoposide, a clinically used cytotoxic agent, was equipotent in causing cytotoxicity in all the stable transfectants. Assessment of DNA damage by Comet assay revealed goniothalamin-induced DNA strand breaks as early as 1 h in vector control but this effect was inhibited in RACK-1 and pc3n3 stably transfected W7.2 cells. This data demonstrate that RACK-1 plays a crucial role in regulating cell death signalling pathways induced by goniothalamin.

Cyanide-induced death of dopaminergic cells is mediated by uncoupling protein-2 up-regulation and reduced Bcl-2 expression

Cyanide is a potent inhibitor of mitochondrial oxidative metabolism and produces mitochondria-mediated death of dopaminergic neurons and sublethal intoxications that are associated with a Parkinson-like syndrome. Cyanide toxicity is enhanced when mitochondrial uncoupling is stimulated following up-regulation of uncoupling protein-2 (UCP-2). In this study, the role of a pro-survival protein, Bcl-2, in cyanide-mediated cell death was determined in a rat dopaminergic immortalized mesencephalic cell line (N27 cells). Following pharmacological up-regulation of UCP-2 by treatment with Wy14,643, cyanide reduced cellular Bcl-2 expression by increasing proteasomal degradation of the protein. The increased turnover of Bcl-2 was mediated by an increase of oxidative stress following UCP-2 up-regulation. The oxidative stress involved depletion of mitochondrial glutathione (mtGSH) and increased H2O2 generation. Repletion of mtGSH by loading cells with glutathione ethyl ester reduced H2O2 generation and in turn blocked the cyanide-induced decrease of Bcl-2. To determine if UCP-2 mediated the response, RNAi knock down was conducted. The RNAi decreased cyanide-induced depletion of mtGSH, reduced H2O2 accumulation, and inhibited down-regulation of Bcl-2, thus blocking cell death. To confirm the role of Bcl-2 down-regulation in the cell death, it was shown that over-expression of Bcl-2 by cDNA transfection attenuated the enhancement of cyanide toxicity after UCP-2 up-regulation. It was concluded that UCP-2 up-regulation sensitizes cells to cyanide by increasing cellular oxidative stress, leading to an increase of Bcl-2 degradation. Then the reduced Bcl-2 levels sensitize the cells to cyanide-mediated cell death.

Stimulatory heterotrimeric GTP-binding protein augments cisplatin-induced apoptosis by upregulating Bak expression in human lung cancer cells

The present study aimed to investigate the effect of the stimulatory heterotrimeric GTP-binding (Gs) protein signaling system on cisplatin-induced apoptosis of lung cancer cells and its underlying mechanism as an attempt to develop a novel strategy to improve the therapeutic efficacy of cisplatin. Overexpression of the constitutively active alpha subunit of Gs (GalphasQL) in A549 human lung cancer cells increased cisplatin-induced apoptosis, and knockdown of Galphas with small hairpin RNA decreased the percentage of apoptotic cells. GalphasQL increased the expression of the proapoptotic proteins B-cell leukemia/lymphoma-2 genes (Bcl-2) homologous antagonist killer protein (Bak) and Bcl-2 associated X protein (Bax), and decreased the expression of the antiapoptotic proteins Bcl-2 and Bcl-Xlong protein. Knockdown of Bak blocked the augmentative effects of GalphasQL. GalphasQL decreased the degradation rate of the Bak protein, and increased Bak mRNA transcript levels. GalphasQL increased Bak-luciferase activity in a protein kinase A and cyclic AMP response element-dependent manner. GalphasQL also augmented cisplatin-induced apoptosis of H1299 human lung cancer cells that lack functional p53. From this study, it is concluded that Galphas augments cisplatin-induced apoptosis of lung cancer cells partially through upregulating Bak expression by increasing transcription and by decreasing the rate of protein degradation.

Valproate, in combination with pemetrexed and cisplatin, provides additional efficacy to the treatment of malignant mesothelioma

PURPOSE

Present chemotherapeutic regimens are marginally efficient in tumor cells being particularly resistant to radiotherapy and/or chemotherapy. We hypothesized that unresponsiveness of tumors to conventional therapeutic agents might be due to inappropriate gene expression resulting from epigenetic modifications and leading to transcriptional silencing. The goal of this study was to evaluate the anticancer effect of a histone deacetylase inhibitor, valproate, on mesothelioma cells in combination with pemetrexed and cisplatin, the usual first-line regimen of chemotherapy for this tumor.

EXPERIMENTAL DESIGN AND RESULTS

We show that valproate augments apoptosis induced by pemetrexed and cisplatin in mesothelioma cell lines and in tumor cells from patient's biopsies. Onset of apoptosis involves both extrinsic and intrinsic pathways requiring enzymatic activities of caspases 8 and 9, respectively. Valproate but not suberoylanilide hydroxamic acid efficiently stimulates the production of reactive oxygen species. The free radical scavenger N-acetylcysteine inhibits apoptosis, indicating that reactive oxygen species are major mediators of valproate activity. As expected, valproate alone or combined with pemetrexed and cisplatin triggers hyperacetylation of histone H3. Bid protein processing in truncated t-Bid and cytochrome c release from mitochondria are significantly increased in the presence of valproate, providing a mechanistic rationale for improvement of the proapoptotic efficacy of cisplatin and pemetrexed. Finally, valproate when combined with pemetrexed and cisplatin prevents tumor growth in mouse models of epithelioid mesothelioma.

CONCLUSIONS

These observations support the potential additional efficacy of valproate in combination with pemetrexed and cisplatin for treatment of malignant mesothelioma.

Inhibitory heterotrimeric GTP-binding proteins inhibit hydrogen peroxide-induced apoptosis by up-regulation of Bcl-2 via NF-kappaB in H1299 human lung cancer cells

Inhibitory heterotrimeric GTP-binding proteins (Gi proteins) mediate a variety of signaling pathways by coupling receptors and effectors to regulate cellular proliferation, differentiation, and apoptosis. However, the role of Gi proteins in the modulation of hydrogen peroxide-induced apoptosis is not clearly understood. Thus, we investigated the effect of Gi proteins on hydrogen peroxide-induced apoptosis and the underlying mechanisms in H1299 human lung cancer cells. The stable expression of constitutively active alpha subunits of Gi1 (Galphai1QL), Gi2, or Gi3 inhibited hydrogen peroxide-induced apoptosis. The expression of Galphai1QL up-regulated Bcl-2 expression, and the knockdown of Bcl-2 with siRNA abolished the anti-apoptotic effect of Galphai1QL. Galphai1 induced the transcription of Bcl-2 by activation of NF-kappaB, which resulted from an increase in NF-kappaB p50 protein. We conclude that Galphai1 inhibits hydrogen peroxide-induced apoptosis of H1299 lung cancer cells by up-regulating the transcription of Bcl-2 through a p50-mediated NF-kappaB activation.

PCPH/ENTPD5 expression confers to prostate cancer cells resistance against cisplatin-induced apoptosis through protein kinase Calpha-mediated Bcl-2 stabilization

Prostate cancer (PCa) frequently develops antiapoptotic mechanisms and acquires resistance to anticancer drugs. Therefore, identifying PCa drug resistance determinants should facilitate designing more effective chemotherapeutic regimens. Recently, we described that the PCPH protein becomes highly expressed in human prostatic intraepithelial neoplasia and in PCa, and that the functional interaction between PCPH and protein kinase Cdelta (PKCdelta) increases the invasiveness of human PCa. Here, we report that the functional interaction between PCPH and a different PKC isoform, PKCalpha, confers resistance against cisplatin-induced apoptosis to PCa cells. This interaction elicits a mechanism ultimately resulting in the posttranslational stabilization and subsequent elevated expression of Bcl-2. Stable knockdown of either PCPH, mt-PCPH, or PKCalpha in PCa cells decreased Ser70-phosphorylated Bcl-2 and total Bcl-2 protein, thereby increasing their cisplatin sensitivity. Conversely, forced expression of the PCPH protein or, in particular, of the mt-PCPH oncoprotein increased the levels of phosphorylated PKCalpha concurrently with those of Ser70-phosphorylated and total Bcl-2 protein, thus promoting cisplatin resistance. Consistently, Bcl-2 knockdown sensitized PCa cells to cisplatin treatment and, more importantly, reversed the cisplatin resistance of PCa cells expressing the mt-PCPH oncoprotein. Moreover, reexpression of Bcl-2 in PCPH/mt-PCPH knockdown PCa cells reversed the cisplatin sensitization caused by PCPH or mt-PCPH down-regulation. These findings identify PCPH and mt-PCPH as important participants in the chemotherapy response of PCa cells, establish a role for PCPH-PKCalpha-Bcl-2 functional interactions in the drug response process, and imply that targeting PCPH expression before, or simultaneously with, chemotherapy may improve the treatment outcome for PCa patients.

Tannic acid-induced apoptosis and -enhanced sensitivity to arsenic trioxide in human leukemia HL-60 cells

Tannic acid (TA), a glucoside of gallic acid polymer, has been shown to possess anti-bacterial, anti-enzymatic, anti-tumor and astringent properties. However, the anti-cancer activity of TA in leukemia is still obscure. In this study, we showed TA-induced apoptotic death in acute myeloid leukemia (AML) HL-60 cells via dose- and time-dependent manner as well as increase of sub-G1 fraction, chromosome condensation, and DNA fragmentation. Further analysis demonstrated the involvement of activation of caspase cascade, cleavage of poly (ADP-ribose) polymerase (PARP), disruption of mitochondrial membrane potential, and release of Cytochrome C, in TA-induced apoptosis. These effects were probably associated with the increase of intracellular superoxide in mitochondrial signaling pathway which attributed to the down-regulation of superoxide dismutase (SOD). Notably, a low dose of TA is sufficient to aggravate arsenic trioxide (As(2)O(3))-induced cytotoxicity in HL-60 cells. Altogether, this study suggested the effects of TA to induce apoptosis in HL-60 and therapeutic potential in AML by being an adjunct to As(2)O(3).

Aminoacetone, a putative endogenous source of methylglyoxal, causes oxidative stress and death to insulin-producing RINm5f cells

Aminoacetone (AA), triose phosphates, and acetone are putative endogenous sources of potentially cytotoxic and genotoxic methylglyoxal (MG), which has been reported to be augmented in the plasma of diabetic patients. In these patients, accumulation of MG derived from aminoacetone, a threonine and glycine catabolite, is inferred from the observed concomitant endothelial overexpression of circulating semicarbazide-sensitive amine oxidases. These copper-dependent enzymes catalyze the oxidation of primary amines, such as AA and methylamine, by molecular oxygen, to the corresponding aldehydes, NH4(+) ion and H2O2. We recently reported that AA aerobic oxidation to MG also takes place immediately upon addition of catalytic amounts of copper and iron ions. Taking into account that (i) MG and H2O2 are reportedly cytotoxic to insulin-producing cell lineages such as RINm5f and that (ii) the metal-catalyzed oxidation of AA is propagated by O2(*-) radical anion, we decided to investigate the possible pro-oxidant action of AA on these cells taken here as a reliable model system for pancreatic beta-cells. Indeed, we show that AA (0.10-5.0 mM) administration to RINm5f cultures induces cell death. Ferrous (50-300 microM) and Fe(3+) ion (100 microM) addition to the cell cultures had no effect, whereas Cu(2+) (5.0-100 microM) significantly increased cell death. Supplementation of the AA- and Cu(2+)-containing culture medium with antioxidants, such as catalase (5.0 microM), superoxide dismutase (SOD, 50 U/mL), and N-acetylcysteine (NAC, 5.0 mM) led to partial protection. mRNA expression of MnSOD, CuZnSOD, glutathione peroxidase, and glutathione reductase, but not of catalase, is higher in cells treated with AA (0.50-1.0 mM) plus Cu(2+) ions (10-50 microM) relative to control cultures. This may imply higher activity of antioxidant enzymes in RINm5f AA-treated cells. In addition, we have found that AA (0.50-1.0 mM) plus Cu(2+) (100 microM) (i) increase RINm5f cytosolic calcium; (ii) promote DNA fragmentation; and (iii) increase the pro-apoptotic (Bax)/antiapoptotic (Bcl-2) ratio at the level of mRNA expression. In conclusion, although both normal and pathological concentrations of AA are probably much lower than those used here, it is tempting to propose that excess AA in diabetic patients may drive oxidative damage and eventually the death of pancreatic beta-cells.