Effectiveness of written exposure therapy for Korean patients with post-traumatic stress disorder: non-randomized treatment-as-usual waitlist-controlled study.

Written exposure therapy (WET) is a five-session exposure-based protocol for treating post-traumatic stress disorder (PTSD). The brevity and tolerability of WET present the potential to overcome barriers in implementing evidence-based therapy for PTSD within the Korean mental healthcare system. This study investigated the effectiveness of WET in Korean patients with PTSD through a waitlist-controlled trial (KCT0008112). A total of 57 patients with PTSD were allocated non-randomly to either WET (n = 27) or treatment-as-usual waitlist groups (n = 30). Both groups were followed up until the twenty-fourth week after the initial session. Primary outcomes assessed included PTSD symptoms, depressive symptoms, and general function. In the WET group, significant improvements were observed in PTSD symptoms, depressive symptoms, and general function compared to the control group. After the waiting period, the waitlist group also participated in WET, and exhibited significant improvement in all scores. The between- and within-group effect sizes were large. The dropout rate in both groups was 10.9%, and the mean satisfaction ratings were 28.24 ± 3.33 (range 22-32; scale range 8-32). The present study provides evidence of WET successfully reducing PTSD and depressive symptoms and improving general function among Korean patients with PTSD. Moreover, WET was well tolerated and received by Korean patients with PTSD.

ISRIB plus bortezomib triggers paraptosis in breast cancer cells via enhanced translation and subsequent proteotoxic stress.

Despite the success of proteasome inhibitors (PIs) in treating hematopoietic malignancies, including multiple myeloma (MM), their clinical efficacy is limited in solid tumors. In this study, we investigated the involvement of the integrated stress response (ISR), a central cellular adaptive program that responds to proteostatic defects by tuning protein synthesis rates, in determining the fates of cells treated with PI, bortezomib (Bz). We found that Bz induces ISR, and this can be reversed by ISRIB, a small molecule that restores eIF2B-mediated translation during ISR, in both Bz-sensitive MM cells and Bz-insensitive breast cancer cells. Interestingly, while ISRIB protected MM cells from Bz-induced apoptosis, it enhanced Bz sensitivity in breast cancer cells by inducing paraptosis, the cell death mode that is accompanied by dilation of the endoplasmic reticulum (ER) and mitochondria. Combined treatment with ISRIB and Bz may shift the fate of Bz-insensitive cancer cells toward paraptosis by inducing translational rescue, leading to irresolvable proteotoxic stress.

PSMD14 Targeting Triggers Paraptosis in Breast Cancer Cells by Inducing Proteasome Inhibition and Ca2+ Imbalance.

PSMD14, a subunit of the 19S regulatory particles of the 26S proteasome, was recently identified as a potential prognostic marker and therapeutic target in diverse human cancers. Here, we show that the silencing and pharmacological blockade of PSMD14 in MDA-MB 435S breast cancer cells induce paraptosis, a non-apoptotic cell death mode characterized by extensive vacuolation derived from the endoplasmic reticulum (ER) and mitochondria. The PSMD14 inhibitor, capzimin (CZM), inhibits proteasome activity but differs from the 20S proteasome subunit-inhibiting bortezomib (Bz) in that it does not induce aggresome formation or Nrf1 upregulation, which underlie Bz resistance in cancer cells. In addition to proteasome inhibition, the release of Ca2+ from the ER into the cytosol critically contributes to CZM-induced paraptosis. Induction of paraptosis by targeting PSMD14 may provide an attractive therapeutic strategy against cancer cells resistant to proteasome inhibitors or pro-apoptotic drugs.

Posttraumatic stress disorder symptoms and neurocognitive functioning in fire fighters: The mediating role of sleep problems and resilience.

BACKGROUND: Firefighters are often exposed to terrible and dangerous scenes due to their duties, and thus have a high risk of developing posttraumatic stress disorder(PTSD). The purpose of the study is to examine the relationship between PTSD symptoms, sleep problems, resilience and neurocognitive functioning of firefighters, and to identify the sequential mediating effects of sleep problems and resilience on the relationship between PTSD symptoms and neurocognitive functioning (especially psychomotor speed and processing speed). METHODS: Data were collected from 325 firefighters in eight fire departments in four regions of Korea. Subjects performed neurocognitive function tests and completed the following questionnaires: Primary Care PTSD Screening, Pittsburgh Sleep Quality Index-K and Connor-Davidson Resilience Scale-2. The correlation and dual mediation effects were analysed using SPSS 22.0 program and PROCESS macro 3.4 program. RESULTS: PTSD symptoms, neurocognitive functioning, sleep problems and resilience were significantly correlated with each other. In the sequential mediation model, the relationship between PTSD and psychomotor speed/processing speed was sequentially mediated by sleep problems and resilience after adjusting for demographic variables. CONCLUSIONS: The PTSD symptoms of firefighters were related to a sequential link between sleep problems, low resilience and decreased neurocognitive function. These findings could serve as a basis for more effective and integrated interventional strategies for facilitating better neurocognitive functioning in firefighters.

Screening of Drug-Induced Steatosis and Phospholipidosis Using Lipid Droplet-Selective Two-Photon Probes.

Lipid droplets (LDs) are organelles that play a major role in regulating the storage of neutral lipids. Dysregulation of LDs is associated with metabolic disorders, such as fatty liver diseases, obesity, diabetes, and atherosclerosis. We have developed LD-selective small-molecule fluorescence probes (probes 3 and 4) that are available for both one- and two-photon microscopy, employing live or fixed cells. We found that probes 3 and 4 sensitively detect the increased LDs in response to oleic acid or endoplasmic reticulum stress, both in cells and tissues of the liver. The narrow absorption and emission bands of probes 3 and 4 allow multicolor imaging for the study of the role of LDs in pathophysiology and LD-associated signaling by the coapplication of the probes for different organelles or antibodies against specific proteins. In addition, we show here, for the first time, that two-photon microscopy imaging using our LD-selective probes with LysoTracker provides a novel method for screening drugs to potentially induce steatosis and/or phospholipidosis.

The relationship between the pattern of shift work and sleep disturbances in Korean firefighters.

PURPOSE: Sleep disturbances are prevalent in firefighters, but the relationship between patterns of shift work and sleep disturbances has not yet been investigated. Here, this relationship has been evaluated in Korean firefighters. METHODS: A cross-sectional study was conducted using an online questionnaire, which captured demographic, psychosocial and work-related characteristics. Sleep disturbance was assessed using the insomnia severity index (ISI). The relationship between insomnia and work-related factors (including type of shift work and the frequency of emergency events and off-duty work which means overtime work on off days) was analyzed. RESULTS: A total of 9810 firefighters completed the survey, representing approximately 21.5% of all Korean firefighters; data from 9738 subjects were included in the analysis. All firefighter roles were significantly associated with insomnia; the odds ratio (OR) was 2.456 (95% confidence interval [CI] 1.461-4.128) for fire suppression and 1.871 (95% CI 1.105-3.167) for the emergency medical services and rescue. However, the pattern of shift work did not show a statistically significant relationship. The OR increased along with the frequency of emergency events and off-duty work (p value for trend < 0.05). CONCLUSIONS: This study found a significant association between the frequency of emergency and off-duty work and insomnia in Korean firefighters, whereas the pattern of shift work showed no significant relationship. Therefore, measures to reduce the frequency of emergency and off-duty work are required to prevent sleep disturbances in firefighters.

Psychosocial Support during the COVID-19 Outbreak in Korea: Activities of Multidisciplinary Mental Health Professionals.

As of April 18, 2020, there have been a total of 10,653 confirmed cases and 232 deaths due to coronavirus disease 2019 (COVID-19) in Korea. The pathogen spread quickly, and the outbreak caused nationwide anxiety and shock. This study presented the anecdotal records that provided a detailed process of the multidisciplinary teamwork in mental health during the COVID-19 outbreak in the country. Psychosocial support is no less important than infection control during an epidemic, and collaboration and networking are at the core of disaster management. Thus, a multidisciplinary team of mental health professionals was immediately established and has collaborated effectively with its internal and external stakeholders for psychosocial support during the COVID-19 outbreak.

Targeting interleukin-6 as a strategy to overcome stroma-induced resistance to chemotherapy in gastric cancer.

BACKGROUND: Although the tumor stroma in solid tumors like gastric cancer (GC) plays a crucial role in chemo-resistance, specific targets to inhibit the interaction between the stromal and cancer cells have not yet been utilized in clinical practice. The present study aims to determine whether cancer-associated fibroblasts (CAFs), a major component of the tumor stroma, confer chemotherapeutic resistance to GC cells, and to discover potential targets to improve chemo-response in GC. METHODS: To identify CAF-specific proteins and signal transduction pathways affecting chemo-resistance in GC cells, secretome and transcriptome analyses were performed. We evaluated the inhibiting effect of CAF-specific protein in in vivo and in vitro models and investigated the expression of CAF-specific protein in human GC tissues. RESULTS: Secretome and transcriptome data revealed that interleukin-6 (IL-6) is a CAF-specific secretory protein that protects GC cells via paracrine signaling. Furthermore, CAF-induced activation of the Janus kinase 1-signal transducer and activator of transcription 3 signal transduction pathway confers chemo-resistance in GC cells. CAF-mediated inhibition of chemotherapy-induced apoptosis was abrogated by the anti-IL-6 receptor monoclonal antibody tocilizumab in various experimental models. Clinical data revealed that IL-6 was prominently expressed in the stromal portion of GC tissues, and IL-6 upregulation in GC tissues was correlated with poor responsiveness to chemotherapy. CONCLUSIONS: Our data provide plausible evidence for crosstalk between GC cells and CAFs, wherein IL-6 is a key contributor to chemoresistance. These findings suggest the potential therapeutic application of IL-6 inhibitors to enhance the responsiveness to chemotherapy in GC.

Lercanidipine Synergistically Enhances Bortezomib Cytotoxicity in Cancer Cells via Enhanced Endoplasmic Reticulum Stress and Mitochondrial Ca2+ Overload.

The proteasome inhibitor (PI), bortezomib (Btz), is effective in treating multiple myeloma and mantle cell lymphoma, but not solid tumors. In this study, we show for the first time that lercanidipine (Ler), an antihypertensive drug, enhances the cytotoxicity of various PIs, including Btz, carfilzomib, and ixazomib, in many solid tumor cell lines by inducing paraptosis, which is accompanied by severe vacuolation derived from the endoplasmic reticulum (ER) and mitochondria. We found that Ler potentiates Btz-mediated ER stress and ER dilation, possibly due to misfolded protein accumulation, in MDA-MB 435S cells. In addition, the combination of Btz and Ler triggers mitochondrial Ca2+ overload, critically contributing to mitochondrial dilation and subsequent paraptotic events, including mitochondrial membrane potential loss and ER dilation. Taken together, our results suggest that a combined regimen of PI and Ler may effectively kill cancer cells via structural and functional perturbations of the ER and mitochondria.

Pyrrolidine dithiocarbamate reverses Bcl-xL-mediated apoptotic resistance to doxorubicin by inducing paraptosis.

Elevated Bcl-xL expression in cancer cells contributes to doxorubicin (DOX) resistance, leading to failure in chemotherapy. In addition, the clinical use of high-dose doxorubicin (DOX) in cancer therapy has been limited by issues with cardiotoxicity and hepatotoxicity. Here, we show that co-treatment with pyrrolidine dithiocarbamate (PDTC) attenuates DOX-induced apoptosis in Chang-L liver cells and human hepatocytes, but overcomes DOX resistance in Bcl-xL-overexpressing Chang-L cells and several hepatocellular carcinoma (HCC) cell lines with high Bcl-xL expression. Additionally, combined treatment with DOX and PDTC markedly retarded tumor growth in a Huh-7 HCC cell xenograft tumor model, compared to either mono-treatment. These results suggest that DOX/PDTC co-treatment may provide a safe and effective therapeutic strategy against malignant hepatoma cells with Bcl-xL-mediated apoptotic defects. We also found that induction of paraptosis, a cell death mode that is accompanied by dilation of the endoplasmic reticulum and mitochondria, is involved in this anti-cancer effect of DOX/PDTC. The intracellular glutathione levels were reduced in Bcl-xL-overexpressing Chang-L cells treated with DOX/PDTC, and DOX/PDTC-induced paraptosis was effectively blocked by pretreatment with thiol-antioxidants, but not by non-thiol antioxidants. Collectively, our results suggest that disruption of thiol homeostasis may critically contribute to DOX/PDTC-induced paraptosis in Bcl-xL-overexpressing cells.

Carboxylesterase-2-Selective Two-Photon Ratiometric Probe Reveals Decreased Carboxylesterase-2 Activity in Breast Cancer Cells.

Human carboxylesterase-2 (CE2) is a carboxylesterase that catalyzes the hydrolysis of endogenous and exogenous substrates. Abnormal CE2 levels are associated with various cancers, and CE2 is a key mediator of anticancer prodrugs, including irinotecan. Here, we developed a two-photon ratiometric probe for detecting CE2 activity using succinate ester as a recognition site for CE2. The probe showed high selectivity to CE2, a clear emission color change, high photostability, and bright two-photon microscopy (TPM) imaging capability, allowing the quantitative detection of CE2 activity in live cells. Using TPM ratio analysis, we show for the first time that CE2 activity was much lower in breast cancer cells than in normal cells. In CE2 overexpression studies, cancer cells had a markedly enhanced sensitivity to the cytotoxic effect of irinotecan, corresponding well with the TPM ratio of the probe. These results may provide useful information for quantitatively measuring CE2 activity in situ and predicting the responsiveness to anticancer drugs.

The relationship between morningness-eveningness and resilience in mood disorder patients.

BACKGROUND: There is some evidence that resilience is related to mental illness. Patients with a mood disorder have a tendency to show eveningness, and they tend to be less resilient. However, no study has investigated the association between resilience and morningness-eveningness in patients with a mood disorder. The aim of this study was to explore whether morningness-eveningness is related to resilience in patients with a mood disorder. METHODS: We recruited 224 patients with major depressive disorder (MDD), 77 with bipolar disorder (BD), and 958 control participants. Morningness-eveningness and resilience were evaluated using the Composite Scale of Morningness (CS) and the Connor-Davidson Resilience Scale (CD-RISC), respectively. RESULTS: The CD-RISC scores were significantly lower in patients with MDD, followed by those with BD, than those of the control group. The CD-RISC score was positively correlated with the CS score in patients with MDD and BD. Multiple linear regression analyses revealed that the CS score was significantly associated with the CD-RISC score after controlling for the possible influence of age, gender, length of education, economic status, onset age, and suicide attempt history in the MDD group. However, the association did not reach statistical significance in patients with BD. CONCLUSIONS: Higher resilience was positively correlated with morningness in patients with MDD or BD. In multiple regression analysis, a significant linear relationship was observed between resilience and morningness only in patients with MDD. The biological mechanism underlying the relationship between morningness-eveningness and resilience should be explored.

An international comparison of occupational health guidelines for the management of mental disorders and stress-related psychological symptoms.

BACKGROUND: We compared available guidelines on the management of mental disorders and stress-related psychological symptoms in an occupational healthcare setting and determined their development and reporting quality. METHODS: To identify eligible guidelines, we systematically searched National Guideline Clearinghouse, Guidelines International Network Library and PubMed. Members of the International Commission on Occupational Health (ICOH), were also consulted. Guidelines recommendations were compared and reporting quality was assessed using the AGREE II instrument. RESULTS: Of 2126 titles retrieved, 14 guidelines were included: 1 Japanese, 2 Finnish, 2 Korean, 2 British and 7 Dutch. Four guidelines were of high-reporting quality. Best described was the Scope and Purpose, and the poorest described were competing interests (Editorial independence) and barriers and facilitators for implementation (Applicability). Key recommendations were often difficult to identify. Most guidelines recommend employing an inventory of symptoms, diagnostic classification, performance problems and workplace factors. All guidelines recommend specific return-to-work interventions, and most agreed on psychological treatment and communication between involved stakeholders. DISCUSSION: Practice guidelines to address work disability due to mental disorders and stress-related symptoms are available in various countries around the world, however, these guidelines are difficult to find. To promote sharing, national guidelines should be accessible via established international databases. The quality of the guideline's developmental process varied considerably. To increase quality and applicability, guideline developers should adopt a common structure for the development and reporting of their guidelines, for example Appraisal of Guidelines for Research and Evaluation (AGREE) criteria. Owing to differences in social systems, developers can learn from each other through reviews of this kind.

Dicoumarol sensitizes renal cell carcinoma Caki cells to TRAIL-induced apoptosis through down-regulation of Bcl-2, Mcl-1 and c-FLIP in a NQO1-independent manner.

In the study, we investigated the effect of dicoumarol, an anti-coagulant agent with the inhibitory activity of NAD(P)H quinone oxidoreductase 1 (NQO1), on TRAIL-induced apoptosis in renal cancer cell. Combined treatment with dicoumarol and TRAIL significantly induced apoptosis in various human renal carcinoma cells including Caki, ACHN, and A498, but not in normal human skin fibroblasts (HSF) and mouse kidney cells (TMCK-1). When we elucidated the relevance of NQO1 in dicoumarol plus TRAIL-mediated apoptosis, both ES936 (a NQO1 inhibitor) and knockdown of NQO1 with siRNA had no effect on TRAIL-mediated apoptosis, suggesting that the stimulating effect of dicoumarol on TRAIL-mediated apoptosis is independent of NQO1 activity. We found that dicoumarol transcriptionally down-regulated Bcl-2 expression via inhibition of NF-κB and CREB activity, whereas it down-regulated Mcl-1 and c-FLIP expression at the post-translational level. Overexpression of Bcl-2, Mcl-1, or c-FLIP overcame the dicoumarol plus TRAIL-induced apoptosis, indicating that down-regualtion of these anti-apoptotic proteins may critically contribute to the sensitizing effect of dicoumarol on TRAIL-mediated apoptosis.

Regulation of the subcellular shuttling of Sgo1 between centromeres and chromosome arms by Aurora B-mediated phosphorylation.

A minor fraction of cohesin complexes at chromosome arms is not removed by the prophase pathway, and maintained until metaphase and enriched at centromeres. Sgo1 localizes to chromosome arms from prophase to metaphase, and is indispensable for removing cohesin complexes from chromosome arms. However, it has not been established how the chromosome arm localization of Sgo1 leads to the establishment of cohesion on chromosomes. Here, we report that Aurora B kinase interacts with and phosphorylates Sgo1 in vitro and in vivo. Furthermore, the phosphorylation of Sgol by Aurora B kinase regulated the distribution of Sgo1 between centromeres and chromosome arms, and the expression of Aurora B kinase-dead mutants of Sgo1 caused mislocalization from centromeres to chromosome arms. These results suggest Aurora B kinase directly regulates the subcellular distribution of Sgo1 to facilitate the accurate separation of mitotic chromosomes.

Human CLOCK gene-associated attention deficit hyperactivity disorder-related features in healthy adults: quantitative association study using Wender Utah Rating Scale.

Circadian rhythm disturbance is highly prevalent in attention deficit hyperactivity disorder (ADHD). Recently, the association between the CLOCK gene and ADHD has been demonstrated in clinical samples, and the CLOCK gene's role was thought to be mediated by rhythm dysregulation. Meanwhile, ADHD has been suggested as the extreme end of a continuously distributed trait that can be found in the general population. Therefore, we examined two possibilities: (1) an ADHD-related continuous trait may be associated with the CLOCK gene, and (2) this association may be mediated by the degree of individuals' evening preference. To explore these possibilities, we performed a quantitative trait locus association study with a sample of 1,289 healthy adults. The Wender Utah Rating Scale (WURS) and the Composite Scale of Morningness (CSM) were utilized to measure the quantitative traits. Quantitative association analysis was performed using PLINK software. We found that rs1801260 (=T3111C) was associated with WURS scores in both allele-wise (p = 0.018) and haplotype-wise analyses (range of p values: 0.0155-0.0171) in male participants only. After controlling for the CSM total score as a covariate, the strength of the association did not change at all, suggesting that the association was not mediated by evening preference. Despite the very weak association signal, our results provide evidence that the CLOCK gene's association with ADHD in clinical samples may be generalizable to traits measured in the normal population. However, as our results failed to show a mediating role of evening preference, ongoing efforts are needed to identify the mechanisms by which the CLOCK gene determines ADHD-related traits.

Protective Behaviors Against COVID-19 and Related Factors in Korean Adults With Depressive Symptoms: Results From an Analysis of the 2020 Korean Community Health Survey.

OBJECTIVE: This study evaluated protective behaviors against coronavirus disease-2019 (COVID-19) and related factors in individuals with depressive symptoms. METHODS: This cross-sectional study included data from the 2020 Korean Community Health Survey. Depressive symptoms, COVID- 19 protection behaviors, and related factors were investigated in 228,485 people. Chi-square test and logistic regression analysis were used to analyze categorical variables. Statistical analysis was performed using SPSS software (version 27.0). RESULTS: In the study, 3.9% (n=8,970) had depressive symptoms. The prevalence of depressive symptoms was higher in individuals in their 19-39 years , and ≥60s than in those in their 40-59 years (p<0.001). Lower education level and household income were associated with a higher prevalence of depression (p<0.001). Among the various occupations, service workers had the highest prevalence of depressive symptoms (p<0.001). Individuals with depressive symptoms were less likely to adopt protective behaviors against COVID-19 (p<0.001) or exhibit concerns regarding death and economic damage (p<0.001) compared to individuals without depressive symptoms. Individuals with depressive symptoms were more likely to have unhealthy behaviors than those without depressive symptoms (p<0.001). Individuals with depressive symptoms considered that the COVID-19 response by the government and other organizations was inadequate (p<0.001). CONCLUSION: During the COVID-19 pandemic, individuals with depressive symptoms faced greater challenges in adopting protective behaviors. Therefore, it is crucial to develop strategies to protect people with depressive symptoms during another pandemic in the future.

Akt enhances the vulnerability of cancer cells to VCP/p97 inhibition-mediated paraptosis.

Valosin-containing protein (VCP)/p97, an AAA+ ATPase critical for maintaining proteostasis, emerges as a promising target for cancer therapy. This study reveals that targeting VCP selectively eliminates breast cancer cells while sparing non-transformed cells by inducing paraptosis, a non-apoptotic cell death mechanism characterized by endoplasmic reticulum and mitochondria dilation. Intriguingly, oncogenic HRas sensitizes non-transformed cells to VCP inhibition-mediated paraptosis. The susceptibility of cancer cells to VCP inhibition is attributed to the non-attenuation and recovery of protein synthesis under proteotoxic stress. Mechanistically, mTORC2/Akt activation and eIF3d-dependent translation contribute to translational rebound and amplification of proteotoxic stress. Furthermore, the ATF4/DDIT4 axis augments VCP inhibition-mediated paraptosis by activating Akt. Given that hyperactive Akt counteracts chemotherapeutic-induced apoptosis, VCP inhibition presents a promising therapeutic avenue to exploit Akt-associated vulnerabilities in cancer cells by triggering paraptosis while safeguarding normal cells.

Monensin, a polyether ionophore antibiotic, overcomes TRAIL resistance in glioma cells via endoplasmic reticulum stress, DR5 upregulation and c-FLIP downregulation.

Tumor necrosis factor-related apoptosis-induced ligand (TRAIL) is preferentially cytotoxic to cancer cells over normal cells. However, many cancer cells, including malignant glioma cells, tend to be resistant to TRAIL. Monensin (a polyether ionophore antibiotic that is widely used in veterinary medicine) and salinomycin (a compound that is structurally related to monensin and shows cancer stem cell-inhibiting activity) are currently recognized as anticancer drug candidates. In this study, we show that monensin effectively sensitizes various glioma cells, but not normal astrocytes, to TRAIL-mediated apoptosis; this occurs at least partly via monensin-induced endoplasmic reticulum (ER) stress, CHOP-mediated DR5 upregulation and proteasome-mediated downregulation of c-FLIP. Interestingly, other polyether antibiotics, such as salinomycin, nigericin, narasin and lasalocid A, also stimulated TRAIL-mediated apoptosis in glioma cells via ER stress, CHOP-mediated DR5 upregulation and c-FLIP downregulation. Taken together, these results suggest that combined treatment of glioma cells with TRAIL and polyether ionophore antibiotics may offer an effective therapeutic strategy.

Nutlin-3, a small-molecule MDM2 inhibitor, sensitizes Caki cells to TRAIL-induced apoptosis through p53-mediated PUMA upregulation and ROS-mediated DR5 upregulation.

Nutlin-3 is a novel small-molecule antagonist of the human homolog of mouse double minute (MDM2) that binds MDM2 in the p53-binding pocket and activates the p53 signaling pathway. In this study, we show that nutlin-3 sensitizes Caki human renal cancer cells, but not normal human skin fibroblast (HSF) cells or human mesangial cells, to TRAIL-mediated apoptosis. Combined treatment with nutlin-3 and TRAIL markedly induces apoptosis in HCT116 cells (p53 wild type), but not in HCT116 p53-/- cells, suggesting that p53 is critical for the sensitizing effect of nutlin-3 on TRAIL-induced apoptosis. Pretreatment with N-acetylcysteine (NAC) significantly inhibited nutlin-3-induced DR5 upregulation and cell death induced by the combined treatment with nutlin-3 and TRAIL, suggesting that reactive oxygen species (ROS) mediate nutlin-3-induced DR5 upregulation, which contributes toward TRAIL-mediated apoptosis. However, the upregulation of the p53-mediated protein p53 upregulated modulator of apoptosis (PUMA) by nutlin-3 is likely to be ROS independent because antioxidants failed to block PUMA upregulation. Interestingly, a combined treatment with NAC and PUMA small interfering RNAs significantly blocks nutlin-3-induced and TRAIL-induced apoptosis. Therefore, the present study shows that nutlin-3 enhances TRAIL-induced apoptosis in human renal cancer cells by ROS-mediated or p53-mediated DR5 upregulation and p53-induced PUMA upregulation. These results may offer a novel therapeutic approach to TRAIL-based cancer therapy.