Multiplexed discrimination of SARS-CoV-2 variants via duplex-specific nuclease combined MALDI-TOF MS.

The frequent mutations in SARS-CoV-2 significantly increase the virus's pathogenicity and transmissibility while also diminishing the effectiveness of vaccines. Consequently, assays capable of rapidly and simultaneously identifying multiple SARS-CoV-2 variants are essential for large-scale applications that aim to monitor the evolution of the virus. In this work, we propose a method combining duplex-specific nuclease (DSN)-assisted cyclic amplification with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) detection, enabling the simultaneous identification of multiple SARS-CoV-2 variants at high-throughput. Due to the high specificity of DSN, single-base mutations can be resolved by the method. With ultra-sensitive detection by MALDI-TOF MS, a limit of detection of 100 pM viral RNA fragment was demonstrated. The assay was used for simultaneous identification and typing of SARS-CoV-2 Alpha, Beta, and Delta variants. The whole assay can be accomplished within 3 h, and the amplification is performed under constant temperature, making the technique simple in operation and efficient. It is also feasible to extend the technique to the detection of many other variants of the virus. We expect that the method can add value to the rapid screening of viral variants and can play an important role in pandemic control.

Synthesis and Characterization of Corn Stover-Based Cellulose Triacetate Catalyzed by Ionic Liquid Phosphotungstate.

Cellulose triacetate (CTA) was successfully synthesized from corn stover cellulose (CSC) in the presence of [PyPS]3PW12O40 (IL-POM). The effects of IL-POM contents, reaction temperature, and reaction time on the yield and degree of substitution of CTA were investigated. The synthesized CTA was characterized by SEM, FTIR, and TGA, and the degree of polymerization and solubility in various organic solvents were evaluated. Results showed that the optimum reaction conditions were as follows: 0.04 g of IL-POM, reaction temperature of 140 °C, and reaction time of 45 min, for 0.4 g of CSC and 9 mL of glacial acetic acid. The yield of CTA under optimum reaction conditions was as high as 79.27%, and the degree of substitution was 2.95. SEM and FTIR results showed that the cellulose acetylation occurred, and CTA was synthesized. The TGA results revealed that the decomposition temperature of CTA increased by about 30 °C when compared with that of CSC. A simple, environment-friendly, and efficient process for the preparation of CTA from CSC was constructed, which provides a new pathway for the high-value utilization of corn stover.

Rapid Detection of COVID-19 Using MALDI-TOF-Based Serum Peptidome Profiling.

The outbreak of coronavirus disease 2019 (COVID-19) caused by SARS CoV-2 is ongoing and a serious threat to global public health. It is essential to detect the disease quickly and immediately to isolate the infected individuals. Nevertheless, the current widely used PCR and immunoassay-based methods suffer from false negative results and delays in diagnosis. Herein, a high-throughput serum peptidome profiling method based on matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is developed for efficient detection of COVID-19. We analyzed the serum samples from 146 COVID-19 patients and 152 control cases (including 73 non-COVID-19 patients with similar clinical symptoms, 33 tuberculosis patients, and 46 healthy individuals). After MS data processing and feature selection, eight machine learning methods were used to build classification models. A logistic regression machine learning model with 25 feature peaks achieved the highest accuracy (99%), with sensitivity of 98% and specificity of 100%, for the detection of COVID-19. This result demonstrated a great potential of the method for screening, routine surveillance, and diagnosis of COVID-19 in large populations, which is an important part of the pandemic control.

lncRNA TUG1-Mediated Mir-142-3p Downregulation Contributes to Metastasis and the Epithelial-to-Mesenchymal Transition of Hepatocellular Carcinoma by Targeting ZEB1.

BACKGROUND/AIMS: MicroRNA-142-3p (miR-142-3p) is dysregulated in many malignancies and may function as a tumor suppressor or oncogene in tumorigenesis and tumor development. However, few studies have investigated the clinical significance and biological function of miR-142-3p in hepatocellular carcinoma (HCC). METHODS: The expression levels of taurine upregulated gene 1 (TUG1), miR-142-3p, and zinc finger E-box-binding homeobox 1 (ZEB1) were evaluated in HCC tissues and cell lines by quantitative real-time PCR. MTT and colony formation assays were used to detect cell proliferation ability, transwell assays were used to assess cell migration and invasion, and luciferase reporter assays were used to examine the interaction between the long noncoding RNA TUG1 and miR-142-3p. Tumor formation was evaluated through in vivo experiments. RESULTS: miR-142-3p was significantly downregulated in HCC tissues, but TUG1 was upregulated in HCC tissues. Knockdown of TUG1 and upregulation of miR-142-3p inhibited cell proliferation, cell migration, cell invasion, and the epithelial-mesenchymal transition (EMT). miR-142-3p was found to be a prognostic factor of HCC, and the mechanism by which TUG1 upregulated ZEB1 was via direct binding to miR-142-3p. In vivo assays showed that TUG1 knockdown suppressed cell proliferation and the EMT in nude mice. CONCLUSION: The results of this study suggest that the TUG1/miR-142-3p/ ZEB1 axis contributes to the formation of malignant behaviors in HCC.

[Mutation analysis of NTRK1 gene in a family affected with congenital insensitivity to pain with anhidrosis].

OBJECTIVE: To screen for mutations of NTRK1 gene in a Chinese family affected with congenital insensitivity to pain with anhidrosis (CIPA). METHODS: Genomic DNA was extracted from the proband and her family members. All of the 17 exons and intron-exon boundaries of the NTRK1 gene were analyzed by direct Sanger sequencing. For the deletional mutation, the PCR products were subjected to T-A cloning and sequencing to verify the mutation. RESULTS: NTRK1 gene analysis revealed that proband has carried a c.1786C>T (p.Arg596*) nonsense mutation inherited from her mother and a novel deletional mutation c.1928-2028+23del from her father. Her elder brother only carried the deletional mutation. CONCLUSION: The diagnosis of CIPA relied on typical clinical symptoms of no pain, anhidrosis and intellectual disability and detection of the biallelic NTRK1 mutations. The novel deletional mutation has enriched the spectrum of NTRK1 mutations.

Analysis of characteristics and causes of gas explosion accidents: a historical review of coal mine accidents in China.

Objectives This study aimed to provide greater insight into the characteristics of severe and extraordinarily severe gas explosion accidents (SESGEAs). Methods. The study analyzed the accident characteristics and causes of SESGEAs. As an example, we conducted a specialized case analysis using the 24Model (fourth edition) on the recent Baoma coal mine gas explosion. Results. SESGEA data are characterized by greater volatility, with significant differences in the geographical distribution, temporal distribution and attributed characteristics of the accidents. From the accident analysis: chaotic ventilation management was the most serious accident cause of SESGEAs; unsafe acts related to ventilation operations accounted for 18.51% of all unsafe acts; coal miners lack professional safety knowledge and have a serious fluke mentality in mining work; enterprises have insufficient enforcement of safety procedure documents, and lack of attention to the allocation of underground human resources and safety training systems; and the importance of safety, the role of the safety department and satisfaction with safety facilities have become the most serious missing items of safety culture. Conclusion. This study can provide important data support and management basis to assist mine operators in developing more targeted accident prevention strategies.

Formation and function of multiciliated cells.

In vertebrates, multiciliated cells (MCCs) are terminally differentiated cells that line the airway tracts, brain ventricles, and reproductive ducts. Each MCC contains dozens to hundreds of motile cilia that beat in a synchronized manner to drive fluid flow across epithelia, the dysfunction of which is associated with a group of human diseases referred to as motile ciliopathies, such as primary cilia dyskinesia. Given the dynamic and complex process of multiciliogenesis, the biological events essential for forming multiple motile cilia are comparatively unelucidated. Thanks to advancements in genetic tools, omics technologies, and structural biology, significant progress has been achieved in the past decade in understanding the molecular mechanism underlying the regulation of multiple motile cilia formation. In this review, we discuss recent studies with ex vivo culture MCC and animal models, summarize current knowledge of multiciliogenesis, and particularly highlight recent advances and their implications.

Comparative study of fault tree analysis and 24Model: taking the cause analysis of the Quanzhou Xinjia Hotel collapse accident as an example.

A comparative study was conducted to compare the accident cause analysis methods of fault tree analysis (FTA) and 24Model. A major accident - the Xinjia Hotel collapse accident - was selected as the research object, the causes of the accident were reanalysed and accident prevention countermeasures were designed based on 24Model and FTA, respectively, and the systematic characteristics of 24Model were summarized. The research shows that both 24Model and FTA can carry out risk assessment, accident cause analysis and preventive countermeasure design based on their own rules. Different from FTA, 24Model has static and dynamic structures of specific forms, the definition of causes and factors in the model is more comprehensive and the analysis method is more hierarchical and normative. 24Model can analyse the deep-level cultural and system causes, but the analysis process does not use quantitative methods, only qualitative methods. 24Model has eight systematic characteristics, such as integrity, hierarchy and dynamics.

MazF-rolling circle amplification combined MALDI-TOF MS for site-specific detection of N6-methyladenosine RNA.

N6-methyladenosine (m6A) is one of the most abundant chemical modifications in RNA and has vital significance in cellular processes and tumor development. However, the accurate analysis of site-specific m6A modification remains a challenge. In this work, a MazF endoribonuclease activated rolling circle amplification (MazF-RCA) combined MALDI-TOF MS assay is developed for the detection of site-specific m6A-RNA. MazF endoribonuclease can specifically cleave the ACA motif, leaving methylated (m6A)CA motif intact. The intact methylated RNA can then be amplified through rolling circle amplification, and the generated reporter oligonucleotides are detected by MALDI-TOF MS. The assay exhibits good quantification ability, presenting a wide linear range (100 fM to 10 nM) with the limit-of-detection lower than 100 fM. Additionally, the assay can accurately detect methylated RNA in the presence of large amount of non-methylated RNA with a relative abundance of methylated RNA down to 0.5%. The developed assay was further applied to detect m6A-RNA spiked in MCF-7 cell RNA extracts, with the recovery rates in the range of 90.64-106.93%. The present assay provides a novel platform for the analysis of site-specific m6A-RNA at high specificity and sensitivity, which can promote the study of RNA methylation in clinical and biomedical research.

Meta-analysis of risk factors for cardiovascular disease in patients with rheumatoid arthritis.

BACKGROUND: Cardiovascular disease (CVD) is a common complication of rheumatoid arthritis (RA). We aimed to explore the risk factors for cardiovascular disease in patients with rheumatoid arthritis and provide a scientific basis on effective prevention and treatments for CVD in RA patients. METHODS: We searched for a combination of the subject words and free words involved arthritis, rheumatoid, CVD, heart disease, vascular disease, risk factors, etc. from China Knowledge Network, Wanfang, Vip, China Biomedical Literature Database, Pubmed, Embase, Web of Science, Cochrane and other databases for documents published in public in 2000-October 2022.RevMan 5.3 and Stata14.0 analysis software was used to perform a meta-analysis of case-control and cohort studies on risk factors of CVDs in patients with RA published from 2000 to 2022.The Egger method was used to determine whether there was publication bias. RESULTS: Seventeen pieces of literature were included in this meta-analysis. We explored the associations between CVD and different clinical characters such as DAS28 score, rheumatoid factor, triglyceride, age, sex, C-reactive protein, total cholesterol (TC), hypertension, and D dimer. High serum levels of C-reactive protein, TC, and D-dimer, as well as hypertension, are the main risk factors for CVD in patients with RA. The OR and 95% CI of C-reactive protein were 2.06 (1.91-2.23), RR and 95% CI of TC were 1.7 (1.49-1.93), RR and 95% CI of hypertension were 3.58 (2.37-5.40), as well as OR and 95% CI of D dimer were 2.83 (1.48-5.40).Our results performed by the meta-analysis were reliable, with low publication bias existed. CONCLUSION: C-reactive protein, TC, hypertension, and D dimer are the main risk factors for CVD in patients with RA. No protective factors were found.

Prevalence of depression and anxiety, and associated factors, among Chinese primary and high school students: A cross-sectional, epidemiological study.

INTRODUCTION: This study aimed to investigate the prevalence of depression and anxiety, and associated factors, among Chinese children and adolescents aged 8-18 years who attend primary or high school. METHODS: A total of 23 005 primary and high school students were recruited from February to December, 2019 for this cross-sectional study. The questionnaire included demographic information, questions assessing suicidality, resilience, depression (Center for Epidemiological Studies Depression Scale for Children), and anxiety (Screen for Child Anxiety Related Disorders). Binary logistic regression was used to analyze the independent correlates of depression and anxiety. RESULTS: Overall, 13.06% of participants experienced depressive symptoms, 22.34% experienced anxiety symptoms, 26.34% experienced transient suicidal ideation, 2.23% had serious suicidal ideation, and 1.46% had a history of suicide attempts. Anxiety (odds ratio [OR], 4.935; 95% confidence interval [CI][4.442-5.485]), suicidality (OR, 2.671; 95% CI[2.203-3.237]), skipping breakfast (OR, 1.920; 95% CI[1.348-2.736]), sleep duration (OR, 0.470; 95% CI[0.398-0.556]) and self-expectations (OR, 1.924; 95% CI[1.550-2.389]) were associated with depression (all p < .05). Depression (OR, 4.424; 95% CI[3.983-4.914]), female sex (OR, 1.903; 95% CI[1.759-2.060]), school-based traumatic experience(s) (OR, 1.905; 95% CI[1.747-2.077]), relationships with teachers (OR, 1.575; 95% CI[1.103-2.249]), and suicidality (OR, 1.467; 95% CI[1.218-1.766]) were associated with anxiety symptoms (all p < .05). DISCUSSION: Depression and anxiety are common among school-age children and adolescents in China. Childhood school- and family-based traumatic experience(s), female sex, and lifestyle factors (eating breakfast, sleep duration, exercising, and Internet use) are significantly associated with mental health among children and adolescents. Developing interventions targeting these factors to protect students from depression and anxiety are needed.

Effects of target tree management on understory regeneration in Pinus massoniana plantations.

To clarify the effects of target tree management on natural forest regeneration, with Pinus massoniana plantations in the low mountainous regions of eastern Sichuan with target tree densities of 100, 150 and 200 trees·hm-2 as test object, we analyzed the effects of management densities on canopy structure, plant diversity, and soil physicochemical properties on understory regeneration. The results showed that the regeneration index increased with management density, which increased 0.08-0.10 in the managed plantations compared with unmanaged sites. When the density of the target trees was 150 trees·hm-2, an increase of 9 regeneration tree species and an increase of 800 trees·hm-2 in quantity were observed. The dominance of herbaceous species was not prominent, but canopy structure was improved, and the regeneration ability of understory plants was enhanced. The impact of habitat factors on the regeneration index ranked as soil total porosity (0.591) > leaf area index (-0.536) > Shannon index (-0.085) > available P (0.053) > total N (-0.007) > Pielou index (-0.005). Target tree management facilitated understory regeneration in the P. massoniana plantations by improving soil pore conditions, reducing leaf area index, and decreasing herbaceous plant diversity index. A management density of 150 trees·hm-2 was more sui-table for target tree management in P. massoniana plantations.

Soil development following glacier retreat shapes metagenomic and metabolomic functioning associated with asynchronous C and N accumulation.

Glacier retreat caused by global warming may result in the variation of soil organic carbon and nutrient cycling. Yet, the dynamic change of soil microbial functional profiles, especially C metabolism-related, with soil development following glacier retreat are still unclear. In the present study, we investigated the soil microbial communities, metagenomic functioning, and metabolomic profiles along the Hailuogou Glacier forefield representing a 120-year chronosequence. The alpha diversity indices of soil bacteria, protozoa and nifH genes showed an upward trend with increased soil ages, and the beta diversity of soil archaea, bacteria, fungi, protozoa, nifH and nirS genes were significantly correlated with soil ages, in which increasing soil C and P while decreased C/N and pH significantly contributed to the differences of soil microbial communities among the analyzed environmental variables. The metagenomic functional genes related to the metabolisms of Glycogen and Cellulosome, Iron Acquisition and Metabolism were significantly decreased with chronosequence, while the utilization of Xylose and Lactate, Potassium Metabolism, Sulfur Metabolism showing an upward trend with soil ages, in which soil C/N ratios and pH were the most influential factors. In addition, soil C and C/N ratios were also significantly correlated to metabolomic compositions, in which the complexity of the metabolite structure increased with soil ages. Our results indicate that glacier retreat may lead to the asynchronous C and N accumulation along the chronosequence, thereby affecting the metagenomic and metabolomic functioning of soil microbial communities related to C metabolisms during soil development following glacier retreat.

Causes of death in female patients with bladder cancer after local tumor excision and radical cystectomy: a contemporary, US population-based analysis.

Surgery is one of the most important treatments for bladder cancer, including local tumor excision and radical cystectomy. At present, studies on the causes of death for contemporary survivors, especially women, who have received different surgical treatments are limited. Therefore, the study used a population-based cohort study in the United States from 2000 to 2017 to analyze causes of death for women who underwent local tumor excision or radical cystectomy stratified by demographics and tumor stage. standardized mortality ratios (SMRs) were calculated based on general population data. In total, 24,040 female patients who underwent surgical treatments were assessed. Of those 20,780 patients undergoing local tumor excision, 36.6% died of bladder cancer, while 63.4% died of other causes. The risk of death from all causes increased in comparation with the general population (SMR 1.85; 95% CI 1.82-1.87), and the most common non-tumor cause of death was from heart diseases (16.2%; SMR 1.13; 95% CI 1.09-1.16). Among women who receive radical cystectomy, 82.3% of deaths occurred within 5 years after surgery. 66.9% deaths resulted from bladder cancer, and the risk of death from all causes significantly higher than that in the general people (SMR 4.67; 95% CI 4.51-4.84). Moreover, the risk of death from non- bladder cancer causes also increased, in particular, such as septicemia (SMR 3.09; 95% CI 2.13-4.34). Causes of death during bladder cancer survivorship after surgery vary by patient and tumor characteristics, and these data provide information regarding primary care for women during postoperative cancer survivorship.

Isothermal gene amplification coupled MALDI-TOF MS for SARS-CoV-2 detection.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been spreading worldwide for more than a year and has undergone several mutations and evolutions. Due to the lack of effective therapeutics and long-active vaccines, accurate and large-scale screening and early diagnosis of infected individuals are crucial to control the pandemic. Nevertheless, the current widely used RT-qPCR-based methods suffer from complicated temperature control, long processing time and the risk of false-negative results. Herein, we present a three-way junction induced exponential rolling circle amplification (3WJ-eRCA) combined MALDI-TOF MS assay for SARS-CoV-2 detection. The assay can detect simultaneously the target nucleocapsid (N) and open reading frame 1 ab (orf1ab) genes of SARS-CoV-2 in a single test within 30 min, with an isothermal process (55 °C). High specificity to discriminate SARS-CoV-2 from other coronaviruses, like SARS-CoV, MERS-CoV and bat SARS-like coronavirus (bat-SL-CoVZC45), was observed. We have further used the method to detect pseudovirus of SARS-CoV-2 in various matrices, e.g. water, saliva and urine. The results demonstrated a great potential of the method for large scale screening of COVID-19, which is an important part of the pandemic control.

A novel in-situ quantitative profiling approach for visualizing changes in lignin and cellulose by stained micrographs.

There is a strong need for low-cost lignocellulosic composition simultaneous localization methodologies to benefit deeper understandings of crop stalk morphology. This study developed a robust quantitative safranin O-fast green staining-based optical microscopy imaging methodology for in-situ simultaneously generating digital profiles of lignin and cellulose in stalk tissues. Foreground extraction and dye residue removal of stained images were adapted. The ratios of normalized red (R), green (G), and blue (B) channel signal intensity, R/B and G/B, were defined as quantitative indicators of lignin and cellulose, respectively. The method was validated on model rice with known bioinformatics, and the results were consistent with those of fluorescence microscopy and immunogold labeling methods. The high-definition spatial in-situ simultaneous profiles of lignin and cellulose in alkali-treated maize stalk tissues and their variations were visualized. This low-cost, cell-scale method is expected to contribute to new discoveries in many areas of biomass refining and plant science.

Effects of Forest Gaps on the Structure and Diversity of Soil Bacterial Communities in Weeping Cypress Forest Plantations.

The decline in forest ecological function caused by pure forest plantations planted in the Yangtze River basin is becoming increasingly serious. To investigate this problem, we selected the local low-efficiency weeping cypress plantations for forest gap transformation. Three forest gap sizes, specifically large, medium, and small gaps, were established, and the effects of gap sizes on soil bacterial community structure and diversity in winter and summer were studied compared to no gaps (CK; control). Compared to CK, forest gaps had a significant effect on soil organic carbon (SOC) and soil total nitrogen (TN), and the highest values of SOC and soil TN under two seasons occurred in large forest gaps. The interactions of forest gap sizes and seasons had significant effects on pH, SOC, TN, and alpha diversity indices, including Simpson, Chao1, and ACE indices. Compared to winter, forest gaps significantly increased the soil bacterial community diversity indices in summer. Forest gap sizes significantly affected the composition of the bacterial community, but the composition of the dominant bacteria at the phyla and genera levels was similar. Linear discriminant effect size (LEfSe) analysis showed that there were 32 indicator bacterial species in two seasons. Co-occurrence network analysis revealed that the relationship of the soil bacterial community at the phyla level was complex, and there was a significant positive correlation among bacterial species. Soil bulk density (BD) and soil moisture (SM) significantly affected the soil bacterial alpha diversity indices. The composition of the dominant bacteria at the phyla level was significantly affected by soil microbial carbon (MBC), whereas the composition of dominant bacteria at the genera level was affected by soil hydrolysable nitrogen (AN) and the carbon/nitrogen (C/N) ratio. In this study, compared to the other forest gaps, large forest gaps were more conducive to the accumulation of soil nutrients, thus improving the structure of the soil bacterial community. Importantly, changes in the soil bacterial community structure due to gap formation may have profound effects on soil biogeochemical processes in weeping cypress forest plantations.

Forest gaps alter the soil bacterial community of weeping cypress plantations by modulating the understory plant diversity.

Weeping cypress is an endemic tree species that is widely planted in China, and the simple stand structure and fragile ecosystem of its plantation are common issues. Exploring the effect of different gap sizes on the soil bacterial community structure of weeping cypress plantations can provide a theoretical basis for the near-natural management of forest plantations. We, therefore, constructed three kinds of forest gaps with different sizes in weeping cypress plantations, namely, small (50-100 m2), medium (100-200 m2), and large gaps (400-667 m2), for identifying the key factors that affect soil bacterial communities following the construction of forest gaps. The results suggested that the herb layer was more sensitive than the shrub layer, while the Simpson, Shannon, and richness indices of the herb layer in plots with gaps were significantly higher than those of designated sampling plots without any gaps (CK). The presence of large gaps significantly increased the understory plant diversity and the Shannon and Simpson indices of the soil bacterial alpha diversity. There were obvious changes in the community composition of soil bacteria following the construction of forest gaps. The dominant bacterial phyla, orders, and functions were similar across the plots with different gap sizes. Of the indicator bacterial species, the abundance of the nitrogen-fixing bacteria, Lysobacter_ yangpyeongensis, and Ensifer_meliloti, was significantly different across plots with different gap sizes and accounted for a large proportion of the bacterial population of plots with medium and large gaps. The understory plant diversity was mostly related to the soil bacterial community than to other soil factors. The results of structural equation modeling indicated that the understory plant diversity was the most important environmental factor in driving the composition and diversity of bacterial communities. The construction of forest gaps significantly improved the understory plant diversity, physicochemical properties of the soil, and bacterial diversity in weeping cypress plantations, and the results of the comprehensive evaluation were in the order: large gaps > small gaps > medium gaps > CK. Our results suggested that large gaps are beneficial for the diversity of above-ground plant communities and underground soil bacterial communities.

Sulfated alginate oligosaccharide exerts antitumor activity and autophagy induction by inactivating MEK1/ERK/mTOR signaling in a KSR1-dependent manner in osteosarcoma.

Alginate oligosaccharide (AOS) has the function to inhibit tumor progression and the sulfated modification can enhance the antitumor activity. To date, the function and mechanism of sulfated AOS (AOS-SO4) in tumors remain largely elusive. We prepared AOS by the enzymatic degradation of alginate, collected AOS-SO4 by sulfating following the canonical procedure. Using these materials, in vitro assays showed that both AOS and AOS-SO4 elicited antitumor effects in osteosarcoma cells. Sulfated modification significantly enhanced the antitumor activity. In addition, AOS-SO4 had obvious effects on cell cycle arrest, apoptosis, and autophagy induction in vitro and in vivo. Mechanistically, we observed that AOS-SO4 treatment triggered proapoptotic autophagy by inhibiting MEK1/ERK/mTOR signaling. The ERK activator reversed AOS-SO4-induced autophagy. More importantly, we found that KSR1 interacted with MEK1 and functioned as a positive regulator of MEK1 protein in osteosarcoma cells. High KSR1 expression was significantly associated with poor survival in osteosarcoma patients. Together, these results suggest that AOS-SO4 has a better antitumor effect in osteosarcoma by inhibiting MEK1/ERK/mTOR signaling, which is KSR1-dependent; thus, AOS-SO4 can be a new potential therapeutic candidate for the treatment of osteosarcoma.