Preparation of Pincer Hafnium Complexes for Olefin Polymerization.

Pincer-type [Cnaphthyl, Npyridine, Namido]HfMe2 complex is a flagship among the post-metallocene catalysts. In this work, various pincer-type Hf-complexes were prepared for olefin polymerization. Pincer-type [Namido, Npyridine, Namido]HfMe2 complexes were prepared by reacting in situ generated HfMe4 with the corresponding ligand precursors, and the structure of a complex bearing 2,6-Et2C6H3Namido moieties was confirmed by X-ray crystallography. When the ligand precursors of [(CH3)R2Si-C5H3N-C(H)PhN(H)Ar (R = Me or Ph, Ar = 2,6-diisopropylphenyl) were treated with in situ generated HfMe4, pincer-type [Csilylmethyl, Npyridine, Namido]HfMe2 complexes were afforded by formation of Hf-CH2Si bond. Pincer-type [Cnaphthyl, Sthiophene, Namido]HfMe2 complex, where the pyridine moiety in the flagship catalyst was replaced with a thiophene unit, was not generated when the corresponding ligand precursor was treated with HfMe4. Instead, the [Sthiophene, Namido]HfMe3-type complex was obtained with no formation of the Hf-Cnaphthyl bond. A series of pincer-type [Cnaphthyl, Npyridine, Nalkylamido]HfMe2 complexes was prepared where the arylamido moiety in the flagship catalyst was replaced with alkylamido moieties (alkyl = iPr, cyclohexyl, tBu, adamantyl). Structures of the complexes bearing isopropylamido and adamantylamido moieties were confirmed by X-ray crystallography. Most of the complexes cleanly generated the desired ion-pair complexes when treated with an equivalent amount of [(C18H37)2N(H)Me]+[B(C6F5)4]-, which showed negligible activity in olefin polymerization. Some complexes bearing bulky substituents showed moderate activities, even though the desired ion-pair complexes were not cleanly afforded.

Organo- and Organometallic-Catalytic Intramolecular [1,5]-Hydride Transfer/Cyclization Process through C(sp(3) )-H Bond Activation.

The direct functionalization of C(sp(3) )-H bonds is one of the most synthetically powerful research areas in current organic synthesis. Organocatalytic C(sp(3) )-H bond activation reactions have recently been developed in addition to the traditional metal-catalyzed C(sp(3) )-H activation reactions. In this review, we aim to give a brief overview of organo- and organometallic internal redox cascade reactions with respect to the mechanism, the reactivity of hydrogen donors and acceptors, and the migration modes of hydrogen.

Effect of simvastatin on the resistance to EGFR tyrosine kinase inhibitors in a non-small cell lung cancer with the T790M mutation of EGFR.

Although non-small cell lung cancer (NSCLC) tumors with activating mutations in the epidermal growth factor receptor (EGFR) are highly responsive to EGFR tyrosine kinase inhibitors (TKIs) including gefitinib and erlotinib, development of acquired resistance is almost inevitable. Statins show antitumor activity, but it is unknown whether they can reverse EGFR-TKIs resistance in NSCLC with the T790M mutation of EGFR. This study investigated overcoming resistance to EGFR-TKI using simvastatin. We demonstrated that addition of simvastatin to gefitinib enhanced caspase-dependent apoptosis in T790M mutant NSCLC cells. Simvastatin also strongly inhibited AKT activation, leading to suppression of ß-catenin activity and the expression of its targets, survivin and cyclin D1. Both insulin treatment and AKT overexpression markedly increased p-ß-catenin and survivin levels, even in the presence of gefitinib and simvastatin. However, inhibition of AKT by siRNA or LY294002 treatment decreased p-ß-catenin and survivin levels. To determine the role of survivin in simvastatin-induced apoptosis of gefitinib-resistant NSCLC, we showed that the proportion of apoptotic cells following treatment with survivin siRNA and the gefitinib-simvastatin combination was greater than the theoretical additive effects, whereas survivin up-regulation could confer protection against gefitinib and simvastatin-induced apoptosis. Similar results were obtained in erlotinib and simvastatin-treated HCC827/ER cells. These findings suggest that survivin is a key molecule that renders T790M mutant NSCLC cells resistant to apoptosis induced by EGFR-TKIs and simvastatin. Overall, these data indicate that simvastatin may overcome EGFR-TKI resistance in T790M mutant NSCLCs via an AKT/ß-catenin signaling-dependent down-regulation of survivin and apoptosis induction.

Duplex ultrasound abnormalities of the lower limb veins might precede clinical venous reflux signs in post-Fontan adolescents and young adults.

OBJECTIVE: After the Fontan operation (ie, direct anastomosis of the caval veins to the pulmonary arteries, constituting right ventricular bypass circulation), high central venous pressure can lead to peripheral venous stasis and venous valvar insufficiency. We hypothesized that post-Fontan patients are at a higher risk of developing lower extremity venous lesions detectable using duplex ultrasound, even if clinical signs of chronic venous disease might not be evident. METHODS: A total of 87 transplantation-free survivors after the Fontan procedure who reached adolescence or young adulthood (current age, 15-30 years) participated in a leg vein duplex ultrasound study. The median age at the Fontan procedure, median age at the vein study, and median interval between the two were 3.65 years (interquartile range [IQR], 3.1-5.3 years), 21.7 years (IQR, 18.9-24.7 years), and 16.6 years (IQR, 14.9-19.4 years), respectively. Duplex ultrasound scanning was performed using a venous ultrasound imaging system (Logiq P7; GE Healthcare). The patients were categorized according to the presence of venous reflux (VR) in the superficial, deep, or perforating venous systems: no VR, superficial VR (SVR), deep VR (DVR), perforating VR (PVR), and a combination of multiple venous systems. Correlation of the duplex ultrasound-detected venous lesions with clinical severity using the modified CEAP (clinical, etiological, anatomical, pathophysiological) classification was analyzed using Spearman's correlation analysis. RESULTS: Leg pain was reported by 48 of 87 patients (55.2%). The duplex ultrasound findings for the cohort were no VR in 21 patients (24.1%), SVR in 22 (25.3%), isolated PVR in 21 (24.1%), and reflux of multiple venous systems in 23 patients, including SVR and PVR in 19, DVR and PVR in 1, and SVR, PVR, and DVR in 3 patients. Although the patients with advanced venous lesions detected by duplex ultrasound tended to have a higher CEAP clinical class (P < .001), VR of any venous system on duplex ultrasound was present even in patients with a lower CEAP clinical class. The CEAP clinical class was C0 for 66 patients (76%), and VR of any venous system was present on duplex ultrasound in 66 patients (76%). CONCLUSIONS: The prevalence of lower extremity venous lesions detected by duplex ultrasound is strikingly high in post-Fontan adolescents and young adults, and duplex ultrasound-detected venous abnormalities can precede clinical manifestations. Early detection and timely intervention for leg vein problems are mandatory for post-Fontan patients, especially for those considered to have risk factors for developing chronic lower extremity venous disease.

Characteristics of Patients with Surgical Closure of an Atrial Septal Defect during Infancy.

Background: Surgical closure of an atrial septal defect (ASD) is infrequently indicated during infancy. We evaluated the clinical characteristics and outcomes of patients who underwent surgical ASD closure during infancy. Methods: A single-center retrospective review was performed for 39 patients (19 males) who underwent surgical ASD closure during infancy between 1993 and 2020. The median body weight percentile at the time of operation was 9.3. Results: During a median follow-up of 60.9 months, 4 late deaths occurred due to chronic respiratory failure. A preoperative history of bronchopulmonary dysplasia (BPD) was the only risk factor for late mortality identified in Cox regression (hazard ratio, 3.54; 95% confidence interval [CI], 1.75-163.04; p=0.015). The 5-year survival rate was significantly lower in patients with preoperative history of BPD (97.0% vs. 50.0%, p<0.001) and preoperative ventilatory support (97.1% vs. 40.4%, p<0.001). There were significant postoperative increases in left ventricular end-diastolic (p=0.017), end-systolic (p=0.014), and stroke volume (p=0.013) indices. A generalized estimated equation model showed significantly better postoperative improvement in body weight percentiles in patients with lower weight percentiles at the time of operation (<10th percentile, p=0.01) and larger indexed ASD diameter (≥45 mm/m2, p=0.025). Conclusion: Patients with ASD necessitating surgical closure during infancy are extremely small preoperatively and remain small even after surgical closure. However, postoperative somatic growth was more prominent in smaller patients with larger defects, which may be attributable to an increase in postoperative cardiac output due to changes in ventricular septal configuration. The benefits of ASD closure in patients with BPD are undetermined.

Association Between Low Serum Phosphate Level and Risk of Falls in Hospitalized Patients Over 50 Years of Age: A Retrospective Observational Cohort Study.

Purpose: Falls are the leading cause of injury among hospitalized patients, particularly among older patients. We investigated the association between serum phosphate (s-phosphate) levels and the risk of in-hospital falls. Patients and Methods: This retrospective observational cohort study included all patients aged over 50 years who were admitted to Yongin Severance Hospital in South Korea between January 2018 and March 2021. Demographic, anthropometric, and biochemical parameters were recorded on admission. S-phosphate levels were classified into three groups: below normal (<2.8 mg/dL), normal (2.8-4.4 mg/dL), and above normal (≥4.5 mg/dL). The normal group was further stratified into tertiles (2.8-3.2, 3.3-3.7, and 3.8-4.4 mg/dL). The incidence of in-hospital falls was compared between the five groups. Logistic regression analyses were performed to assess the association between s-phosphate levels and the incidence of falls during the hospital stay, with clinical factors included as covariates in the multivariable models. Results: A total of 15,485 patients (female: 52.1%) with a median age of 70.0 years (interquartile range: 60.0-79.0 years) were included in the analysis, of whom 295 (1.9%) experienced a fall during the hospital stay. The incidence of falls was significantly higher among patients with lower s-phosphate levels, and this relationship also applied among patients with s-phosphate levels within the normal range as well. The association between lower s-phosphate levels and increased risk of falls remained significant in the adjusted analyses. Conclusion: A lower s-phosphate level on admission was independently associated with an increased risk of in-hospital falls. Further studies are needed to determine whether the s-phosphate level on admission could improve prediction of the risk of in-hospital falls.

Resolution of Postnatal Shock Before Open Heart Surgery in Neonates With Prenatal Diagnoses.

BACKGROUND: The impact of a prenatal diagnosis (PreND) for congenital heart disease on outcomes after neonatal open heart surgery is undetermined. We hypothesized that PreND has a positive impact on surgical outcomes in terms of immediate postnatal intensive care, which may lead to a decreased risk of persistent shock before surgery. METHODS: Among the 949 neonates who underwent open heart surgery between January 2002 and December 2017, 655 patients (69.0%) were diagnosed prenatally (group-PreND) and 294 patients (31.0%) were diagnosed postnatally (group-PostND). Procedural complexity, incidence of postnatal shock (serum lactate >4.0 mmol/L or pH <7.2), hospitalization length of stay, duration of shock, resolution of shock, and in-hospital mortality were compared between the 2 groups. RESULTS: In group-PreND, the procedure-dependent comprehensive Aristotle score (10.8 vs 10.0, P < .001), incidence of extracardiac anomalies (13.0% vs 7.1%, P = .008), heterotaxy syndrome (3.8% vs. 1.0%, P = .021), and postnatal shock (244 of 655 [37.3%] vs 78 of 294 [26.5%], P = .001) were higher than in group-PostND. However, patients in group-PreND were hospitalized earlier after birth (0 day vs 5 days, P < .001), experiencing shorter duration of shock (5.3 hours vs 9.0 hours, P = .01), and, consequently, showing higher incidence of shock resolution (212 of 244 [87%] vs 52 of 78 [67%], P < .001). In-hospital mortality was comparable between the 2 groups (P = .070). CONCLUSIONS: Postnatal shock is more frequently observed in group-PreND. However, prenatal awareness of the disease leads to immediate postnatal initiation of intensive care with shorter exposure to shock, leading to higher probability of shock resolution.

Sexual health knowledge and needs among young adults with congenital heart disease.

Advances in the treatment of congenital heart disease (CHD) have increased life expectancy, entailing medical surveillance for a considerable number of adolescents and young adults with CHD for issues arising in areas such as sexual health. This study aimed to assess the sexual knowledge and the needs for sexual health education among this group. The participants comprised 53 young adult outpatients (27 males, median age: 23 years) who had undergone surgical interventions (median: 3 times) for CHD. The Knowledge related to Safe Sex Practice scale (KSSP), an assessment tool containing 15 questions on sexual knowledge, was administered, and the rates of correct answers for each item and the overall scale were compared with the age and sex of a control group (n = 164). The overall mean KSSP score of the participant group (10.5 ± 1.8) was significantly lower than that of the control group (11.1 ± 1.9, p = .035). The KSSP scores of the participants with low peripheral oxygen saturation (SaO2 < 95%) were significantly lower (9.77 ± 1.85) than those with normal SaO2 (11.06 ± 1.85, p = .009). Regarding sexual health education, the participants reported receiving information about contraception as more important than other areas of sexual health. The rate of incorrect answers was higher for questions regarding natural ways of contraception utilizing infertile periods in the menstrual cycle. Based on an informed understanding of those with CHD, healthcare providers in this field should develop customized sexual health education for adolescents and young adults with CHD and implement customized sexual health education, including effective contraception methods.

Expansion of chromosome territories with chromatin decompaction in BAF53-depleted interphase cells.

Chromosomes are compartmentalized into discrete chromosome territories during interphase in mammalian cells. A chromosome territory is generated by the tendency of chromatin to occupy the smallest shell volume, which is determined by the polymeric properties and interactions of the internal meshwork of the chromatin fiber. Here, we show that BAF53 knockdown by small interfering RNA interference led to the expansion of chromosome territories. This was accompanied by a reduction in chromatin compaction, an increase in the micrococcal nuclease sensitivity of the chromatin, and an alteration in H3-K9 and H3-K79 dimethylation. Interestingly, the BAF53 knockdown cells suffer a cell cycle defect. Despite the significant irregularity and decompaction of the polynucleosomes isolated from the BAF53 knockdown cells, the chromatin loading of H1 and core histones remained unaltered, as did the nucleosome spacing. The histone hyperacetylation and down-regulation of BRG-1, mBrm, and Tip49, the catalytic components of the SWI/SNF complex and the TIP60 complex, respectively, did not expand chromosome territories. These results indicate that BAF53 contributes to the polymeric properties and/or the internal meshwork interactions of the chromatin fiber probably via a novel mechanism.

Factors Influencing Physical Activity in Adolescents with Complex Congenital Heart Disease.

PURPOSE: We aimed to identify factors influencing physical activity in adolescents with complex congenital heart disease. METHODS: We recruited 92 adolescents with complex congenital heart disease from a tertiary medical center in Seoul, measured their levels of physical activity, and identified factors that influenced their physical activity levels using the Global Physical Activity Questionnaire, the New York Heart Association classification, congenital heart disease complexity, the Self-Efficacy Scale, and the Parental Bonding Instrument scale. Stepwise multiple linear regression was used to determine factors influencing physical activity. RESULTS: Total physical activity was higher in males than in females (t=4.46, p<.001). Adolescents who participated in school physical education classes engaged in more physical activity than those who did not (t=6.77, p<.001). Higher self-efficacy (ß=.41, p<.001), male gender (ß=.37, p<.001) and participation in school physical education classes (ß=.19, p=.042) were associated with a higher likelihood of engagement in physical activity. CONCLUSION: It is necessary to develop nursing interventions that enhance self-efficacy in order to promote physical activity in adolescents with complex congenital heart disease. Physical activity should also be promoted in an individualized manner, taking into account gender, disease severity, and parental attitude.

Preparation of Half- and Post-Metallocene Hafnium Complexes with Tetrahydroquinoline and Tetrahydrophenanthroline Frameworks for Olefin Polymerization.

Hafnium complexes have drawn attention for their application as post-metallocene catalysts with unique performance in olefin polymerization. In this work, a series of half-metallocene HfMe2 complexes, bearing a tetrahydroquinoline framework, as well as a series of [Namido,N,Caryl]HfMe2-type post-metallocene complexes, bearing a tetrahydrophenanthroline framework, were prepared; the structures of the prepared Hf complexes were unambiguously confirmed by X-ray crystallography. When the prepared complexes were reacted with anhydrous [(C18H37)2N(H)Me]+[B(C6F5)4]-, desired ion-pair complexes, in which (C18H37)2NMe coordinated to the Hf center, were cleanly afforded. The activated complexes generated from the half-metallocene complexes were inactive for the copolymerization of ethylene/propylene, while those generated from post-metallocene complexes were active. Complex bearing bulky isopropyl substituents (12) exhibited the highest activity. However, the activity was approximately half that of the prototype pyridylamido-Hf Dow catalyst. The comonomer incorporation capability was also inferior to that of the pyridylamido-Hf Dow catalyst. However, 12 performed well in the coordinative chain transfer polymerization performed in the presence of (octyl)2Zn, converting all the fed (octyl)2Zn to (polyolefinyl)2Zn with controlled lengths of the polyolefinyl chain.

Estrogen receptor-alpha mediates the effects of estradiol on telomerase activity in human mesenchymal stem cells.

Sex steroid hormone receptors play a central role in modulating telomerase activity, especially in cancer cells. However, information on the regulation of steroid hormone receptors and their distinct functions on telomerase activity within the mesenchymal stem cell are largely unavailable due to low telomerase activity in the cell. In this study, the effects of estrogen (E2) treatment and function of estrogen receptor alpha (ERalpha) and estrogen receptor beta (ERbeta) on telomerase activity were investigated in human mesenchymal stem cells (hMSCs). Telomerase activity and mRNA expression of the catalytic subunit of telomerase (hTERT) were upregulated by treatment of the cells with E2. The protein concentration of ERalpha was also increased by E2 treatment, and enhancement of ERalpha accumulation in the nucleus was clearly detected with immunocytochemistry. When ERalpha expression was reduced by siRNA transfection into hMSCs, the effect of E2 on the induction of hTERT expression and telomerase activity was diminished. In contrast, the transient overexpression of ERalpha increased the effect of E2 on the expression of hTERT mRNA. These findings indicate that the activation of hTERT expression and telomerase activity by E2 in hMSCs depends on ERalpha, but not on ERbeta.

Synthesis of Ring-Fused 1-Benzazepines via [1,5]-Hydride Shift/7-Endo Cyclization Sequences.

Synthesis of 1-benzazepines has been achieved via a [1,5]-hydride shift/7-endo cyclization sequence. The focus of this research is a direct transformation of 2-(aryl)cyclopropane 1,1-diester derivatives into 1-benzazepines using a cyclopropane moiety as the hydride acceptor in internal redox reactions.

Polystyrene Chain Growth from Di-End-Functional Polyolefins for Polystyrene-Polyolefin-Polystyrene Block Copolymers.

Triblock copolymers of polystyrene (PS) and a polyolefin (PO), e.g., PS-block-poly(ethylene-co-1-butene)-block-PS (SEBS), are attractive materials for use as thermoplastic elastomers and are produced commercially by a two-step process that involves the costly hydrogenation of PS-block-polybutadiene-block-PS. We herein report a one-pot strategy for attaching PS chains to both ends of PO chains to construct PS-block-PO-block-PS directly from olefin and styrene monomers. Dialkylzinc compound containing styrene moieties ((CH2=CHC6H4CH2CH2)2Zn) was prepared, from which poly(ethylene-co-propylene) chains were grown via "coordinative chain transfer polymerization" using the pyridylaminohafnium catalyst to afford di-end functional PO chains functionalized with styrene and Zn moieties. Subsequently, PS chains were attached at both ends of the PO chains by introduction of styrene monomers in addition to the anionic initiator Me3SiCH2Li·(pmdeta) (pmdeta = pentamethyldiethylenetriamine). We found that the fraction of the extracted PS homopolymer was low (~20%) and that molecular weights were evidently increased after the styrene polymerization (ΔMn = 27⁻54 kDa). Transmission electron microscopy showed spherical and wormlike PS domains measuring several tens of nm segregated within the PO matrix. Optimal tensile properties were observed for the sample containing a propylene mole fraction of 0.25 and a styrene content of 33%. Finally, in the cyclic tensile test, the prepared copolymers exhibited thermoplastic elastomeric properties with no breakage up over 10 cycles, which is comparable to the behavior of commercial-grade SEBS.

Outbreak of respiratory tract infections on an islet in Korea: possible Chlamydia pneumoniae infection.

In March 2004, we experienced an outbreak of Chlamydia pneumoniae infection on an islet of Korea. In order to assess the significance of the epidemic, we performed a mass examination of 137 students (7-16 years old; male, 69; female, 58) at a school. The examination consisted of a questionnaire inquiring about respiratory symptoms, a serum antibody test for C. pneumoniae using a microimmunofluorescence (MIF) method and enzyme-linked immunosorbent assay (ELISA), and nasopharyngeal swab tests to detect of the organism by specific PCR and cell culture. The results demonstrated that 72 (58.3%) of the students had respiratory symptoms such as rhinorrhea, a sore throat, and/or cough or fever. The PCR positivity of acute-phase patients was 63% (12/19) and PCR positivity using the culture sample was 94% (18/19). However, the existence of the organism was not confirmed fluorescein isothiocyanate (FITC). ELISA, one of the serological methods utilized, demonstrated, in the same patients, 48% (13/27) positive IgM antibodies at the acute phase of the outbreak, and 16% (3/19) positive IgM antibodies during the convalescent phase. The index value (ID) 3.0 for single-sera IgG was 19% (5/27) and that for IgA was 4% (1/27) at the acute phase; the corresponding percentages in the convalescent phase were 11% (2/19) and 5% (1/19), respectively. However, as regards paired sera, no patient demonstrated a 1.35 ELISA ID value at 2 weeks, or an increased value of 1.0 at 8 weeks after the onset of the outbreak. In the MIF experiment, the percent positivity of unpaired IgM from the acute phase was 58% (11/19). At convalescent phase, this percentage was 47% (9/19); however, the positivity of paired serum IgG was 26% (5/19). In the same sample, the percentage of positive cases demonstrated by both ELISA and MIF approaches for single IgM was 37% (7/19) at the acute phase and 11% (2/19) at the convalescent phase. We were unable to isolate C. pneumoniae by cell culture, but we did obtain sufficient serological and PCR data to consider C. pneumoniae as the causative agent of the outbreak. Meaningful results were acquired in terms of serology, and were compared to the healthy population in Korea. Although it remains necessary to investigate the possibility of co-infection and to determine whether or not this outbreak coincides with the prevalence of influenza, it was unequivocally concluded that this outbreak of C. pneumoniae infection has occurred on an islet of Korea.

Visible Light Photoredox-Catalyzed Arylative Ring Expansion of 1-(1-Arylvinyl)cyclobutanol Derivatives.

A visible light mediated photocatalytic arylation/ring expansion of alkenylcyclobutanols has been developed. This approach provides a mild and operationally simple access to the synthesis of functionalized cyclic ketones from the coupling reaction of alkenylcyclobutanols with aryldiazonium salts.

Sensory Impairment and Health-Related Quality of Life.

BACKGROUND: Sensory impairment is a common condition that exerts negative effects on health-related quality of life (HRQoL) in the elderly. This study aimed to determine the relationship between sensory impairment and HRQoL and identify sensory-specific differences in the HRQoL of elderly. METHODS: This study used data from the Korean National Health and Nutrition Examination Survey V (2010-2012), analyzing 5,260 subjects over 60 years of age who completed ophthalmic and otologic examinations. Vision and hearing impairment were measured and classified. HRQoL was determined according to the European QoL five dimension test (EQ-5D). Multivariate logistic regression analysis and analysis of covariance were performed to identify relationships between sensory impairment and HRQoL dimensions as well as differences in HRQoL scores. RESULTS: In the final adjusted multivariate model, there was a statistically higher proportion of those with dual sensory impairment who reported problems with mobility (adjusted odds ratio [aOR] 2.30, 95% confidence interval [CI] 1.45-5.03), usual activities (aOR 2.32, 95% CI 1.16-4.64), and pain/discomfort among EQ-5D subcategories (aOR 1.79, 95% CI 1.07-2.97). In the EQ-5D dimensions, the means and standard deviations of vision impairment (0.86 [0.01]) and dual sensory impairment (0.84 [0.02]) appeared meaningfully lower than those for no sensory impairment (0.88 [0.00]) or hearing impairment (0.88 [0.01]); P = .02). CONCLUSION: Sensory impairment reduces HRQoL in the elderly. Improvement of HRQoL in the elderly thus requires regular screening and appropriate management of sensory impairment.

Inhibition of autophagy potentiates pemetrexed and simvastatin-induced apoptotic cell death in malignant mesothelioma and non-small cell lung cancer cells.

Pemetrexed, a multitarget antifolate used to treat malignant mesothelioma and non-small cell lung cancer (NSCLC), has been shown to stimulate autophagy. In this study, we determined whether autophagy could be induced by pemetrexed and simvastatin cotreatment in malignant mesothelioma and NSCLC cells. Furthermore, we determined whether inhibition of autophagy drives apoptosis in malignant mesothelioma and NSCLC cells. Malignant mesothelioma MSTO-211H and A549 NSCLC cells were treated with pemetrexed and simvastatin alone and in combination to evaluate their effect on autophagy and apoptosis. Cotreatment with pemetrexed and simvastatin induced greater caspase-dependent apoptosis and autophagy than either drug alone in malignant mesothelioma and NSCLC cells. 3-Methyladenine (3-MA), ATG5 siRNA, bafilomycin A, and E64D/pepstatin A enhanced the apoptotic potential of pemetrexed and simvastatin, whereas rapamycin and LY294002 attenuated their induction of caspase-dependent apoptosis. Our data indicate that pemetrexed and simvastatin cotreatment augmented apoptosis and autophagy in malignant mesothelioma and NSCLC cells. Inhibition of pemetrexed and simvastatin-induced autophagy was shown to enhance apoptosis, suggesting that this could be a novel therapeutic strategy against malignant mesothelioma and NSCLC.

Pemetrexed induces apoptosis in malignant mesothelioma and lung cancer cells through activation of reactive oxygen species and inhibition of sirtuin 1.

Pemetrexed is a multitargeted antifolate used for the treatment of malignant mesothelioma and non-small cell lung cancer (NSCLC). However, the mechanism by which pemetrexed induces apoptosis remains unclear. In the present study, we investigated the involvement of reactive oxygen species (ROS) and sirtuin 1 (SIRT1) in pemetrexed-induced apoptosis in MSTO-211 malignant mesothelioma cells and A549 NSCLC cells. Pemetrexed enhanced caspase-dependent apoptosis, induced intracellular ROS generation, and downregulated SIRT1 in the MSTO-211 and A549 cells. Pemetrexed-induced apoptosis, which was prevented by pretreatment with N-acetyl-cysteine (NAC), was mediated by effects on the mitochondria, including mitochondrial membrane potential transition (MPT) and cytosolic release of cytochrome c, and also involved regulation of SIRT1 expression. Interference with SIRT1 expression using siRNA enhanced pemetrexed-induced apoptosis through mitochondrial dysfunction and ROS generation, whereas resveratrol, an activator of SIRT1, protected against pemetrexed-induced apoptosis. These results show that pemetrexed induces apoptosis in MSTO-211 mesothelioma cells and A549 NSCLC cells through mitochondrial dysfunction mediated by ROS accumulation and SIRT1 downregulation.

Enhanced apoptosis by pemetrexed and simvastatin in malignant mesothelioma and lung cancer cells by reactive oxygen species-dependent mitochondrial dysfunction and Bim induction.

Pemetrexed is a multitarget antifolate currently used for the treatment of malignant mesothelioma and non-small cell lung cancer (NSCLC). Statins, 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors used primarily for hyperlidpidemia, have been studied for their antiproliferative and pro-apoptotic effects. However, the effects of simvastatin on pemetrexed-induced apoptosis have not been investigated. In this study, we investigated whether combination treatment with pemetrexed and simvastatin potentiates the apoptotic activity above that is seen with either drug alone in malignant mesothelioma and NSCLC cells. We found that the combination of pemetrexed and simvastatin induced more extensive caspase-dependent apoptosis than either drug alone in malignant mesothelioma cells (MSTO-211) or NSCLC cells (A549). In addition, reactive oxygen species (ROS) generation in cells treated with both pemetrexed and simvastatin was markedly increased compared to cells treated with either pemetrexed or simvastatin alone. Combination treatment also increased the loss of mitochondrial membrane potential, increased cytosolic release of cytochrome c, and altered expression of inhibitor of apoptosis proteins (IAP) and B-cell lymphoma-2 (Bcl-2) families of apoptosis related proteins. On the other hand, pretreatment with N-acetylcysteine (NAC) prevented apoptosis and mitochondrial dysfunction by pemetrexed and simvastatin. In addition, Bim siRNA conferred protection against apoptosis induced by pemetrexed and simvastatin. These results suggest that combination of pemetrexed and simvastatin potentiates their apoptotic activity beyond that of either drug alone in malignant mesothelioma and lung cancer cells. This activity is mediated through ROS-dependent mitochondrial dysfunction and Bim induction.