m1A in CAG repeat RNA binds to TDP-43 and induces neurodegeneration.

Microsatellite repeat expansions within genes contribute to a number of neurological diseases1,2. The accumulation of toxic proteins and RNA molecules with repetitive sequences, and/or sequestration of RNA-binding proteins by RNA molecules containing expanded repeats are thought to be important contributors to disease aetiology3-9. Here we reveal that the adenosine in CAG repeat RNA can be methylated to N1-methyladenosine (m1A) by TRMT61A, and that m1A can be demethylated by ALKBH3. We also observed that the m1A/adenosine ratio in CAG repeat RNA increases with repeat length, which is attributed to diminished expression of ALKBH3 elicited by the repeat RNA. Additionally, TDP-43 binds directly and strongly with m1A in RNA, which stimulates the cytoplasmic mis-localization and formation of gel-like aggregates of TDP-43, resembling the observations made for the protein in neurological diseases. Moreover, m1A in CAG repeat RNA contributes to CAG repeat expansion-induced neurodegeneration in Caenorhabditis elegans and Drosophila. In sum, our study offers a new paradigm of the mechanism through which nucleotide repeat expansion contributes to neurological diseases and reveals a novel pathological function of m1A in RNA. These findings may provide an important mechanistic basis for therapeutic intervention in neurodegenerative diseases emanating from CAG repeat expansion.

Genome of Halimeda opuntia reveals differentiation of subgenomes and molecular bases of multinucleation and calcification in algae.

Algae mostly occur either as unicellular (microalgae) or multicellular (macroalgae) species, both being uninucleate. There are important exceptions, however, as some unicellular algae are multinucleate and macroscopic, some of which inhabit tropical seas and contribute to biocalcification and coral reef robustness. The evolutionary mechanisms and ecological significance of multinucleation and associated traits (e.g., rapid wound healing) are poorly understood. Here, we report the genome of Halimeda opuntia, a giant multinucleate unicellular chlorophyte characterized by interutricular calcification. We achieve a high-quality genome assembly that shows segregation into four subgenomes, with evidence for polyploidization concomitant with historical sea level and climate changes. We further find myosin VIII missing in H. opuntia and three other unicellular multinucleate chlorophytes, suggesting a potential mechanism that may underpin multinucleation. Genome analysis provides clues about how the unicellular alga could survive fragmentation and regenerate, as well as potential signatures for extracellular calcification and the coupling of calcification with photosynthesis. In addition, proteomic alkalinity shifts were found to potentially confer plasticity of H. opuntia to ocean acidification (OA). Our study provides crucial genetic information necessary for understanding multinucleation, cell regeneration, plasticity to OA, and different modes of calcification in algae and other organisms, which has important implications in reef conservation and bioengineering.

MPK1/SLT2 Links Multiple Stress Responses with Gene Expression in Budding Yeast by Phosphorylating Tyr1 of the RNAP II CTD.

The RNA polymerase II largest subunit C-terminal domain consists of repeated YSPTSPS heptapeptides. The role of tyrosine-1 (Tyr1) remains incompletely understood, as, for example, mutating all Tyr1 residues to Phe (Y1F) is lethal in vertebrates but a related mutant has only a mild phenotype in S. pombe. Here we show that Y1F substitution in budding yeast resulted in a strong slow-growth phenotype. The Y1F strain was also hypersensitive to several different cellular stresses that involve MAP kinase signaling. These phenotypes were all linked to transcriptional changes, and we also identified genetic and biochemical interactions between Tyr1 and both transcription initiation and termination factors. Further studies uncovered defects related to MAP kinase I (Slt2) pathways, and we provide evidence that Slt2 phosphorylates Tyr1 in vitro and in vivo. Our study has thus identified Slt2 as a Tyr1 kinase, and in doing so provided links between stress response activation and Tyr1 phosphorylation.

Impact of Anemia on Cardiovascular Events and All-Cause Death Among Participants Who Received Intense Blood Pressure Treatment: A Secondary Analysis of SPRINT.

Background: To investigate whether anemia is associated with incident cardiovascular events and all-cause death among participants who received intensive blood pressure (BP) treatment in the Systolic Blood Pressure Intervention Trial (SPRINT). Methods: A total of 4394 participants who received intensive BP control (systolic BP < 120 mmHg) in SPRINT were included. Anemia status was self-reported. Our primary outcome was a composite of cardiovascular events, and the secondary outcome was all-cause death. Cox regression was used to compare the incidence of outcomes between participants with anemia and non-anemia. In order to balance the baseline characteristics between the 2 groups, inverse probability of treatment weighting (IPTW) was applied. Hazard ratios (HRs), along with 95% confidence intervals (CIs), were then calculated. Results: There were 4394 participants who received intensive BP control (537 participants with anemia). Participants with anemia were older (mean age 68.86 versus 67.75, p = 0.01) and more likely to be female (64.8% versus 31.8%, p < 0.001). The presence of anemia was strongly associated with composite cardiovascular events after adjusting for potential confounders (HR 1.66, 95% CI 1.18-2.34, p = 0.004). The association remained statistically significant even in the population after IPTW (HR 1.55, 95% CI 1.06-2.27, p = 0.024). The secondary outcome revealed that participants with anemia had a higher rate of all-cause death compared to those without anemia. The HR of all-cause death for participants with anemia was 1.61 (95% CI 1.00-2.57, p = 0.049) in the population after IPTW. Conclusions: Anemia appears to be an independent risk factor for composite cardiovascular events and all-cause death among participants who received intensive BP control in SPRINT. Clinical Trial Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT01206062. All SPRINT anonymized data can be found at the National Heart, Lung and Blood Institute (NHLBI) Biologic Specimen and Data Repository (https://biolincc.nhlbi.nih.gov/home/).

HSP90 and Aha1 modulate microRNA maturation through promoting the folding of Dicer1.

Aha1 is a co-chaperone of heat shock protein 90 (HSP90), and it stimulates the ATPase activity of HSP90 to promote the folding of its client proteins. By employing ascorbate peroxidase (APEX)-based proximity labeling and proteomic analysis, we identified over 30 proteins exhibiting diminished abundances in the proximity proteome of HSP90 in HEK293T cells upon genetic depletion of Aha1. Dicer1 is a top-ranked protein, and we confirmed its interactions with HSP90 and Aha1 by immunoprecipitation followed by western blot analysis. Genetic depletion of Aha1 and pharmacological inhibition of HSP90 both led to reduced levels of Dicer1 protein. Additionally, HSP90 and Aha1 bind preferentially to newly translated Dicer1. Reconstitution of Aha1-depleted cells with wild-type Aha1 substantially rescued Dicer1 protein level, and a lower level of restoration was observed for complementation with the HSP90-binding-defective Aha1-E67K, whereas an Aha1 mutant lacking the first 20 amino acids-which abolishes its chaperone activity-failed to rescue Dicer1 protein level. Moreover, knockdown of Aha1 and inhibition of HSP90 led to diminished levels of mature microRNAs (miRNAs), but not their corresponding primary miRNAs. Together, we uncovered a novel mechanism of HSP90 and Aha1 in regulating the miRNA pathway through promoting the folding of Dicer1 protein, and we also demonstrated that Aha1 modulates this process by acting as an autonomous chaperone and a co-chaperone for HSP90.

The Nrd1-like protein Seb1 coordinates cotranscriptional 3' end processing and polyadenylation site selection.

Termination of RNA polymerase II (RNAPII) transcription is associated with RNA 3' end formation. For coding genes, termination is initiated by the cleavage/polyadenylation machinery. In contrast, a majority of noncoding transcription events in Saccharomyces cerevisiae does not rely on RNA cleavage for termination but instead terminates via a pathway that requires the Nrd1-Nab3-Sen1 (NNS) complex. Here we show that the Schizosaccharomyces pombe ortholog of Nrd1, Seb1, does not function in NNS-like termination but promotes polyadenylation site selection of coding and noncoding genes. We found that Seb1 associates with 3' end processing factors, is enriched at the 3' end of genes, and binds RNA motifs downstream from cleavage sites. Importantly, a deficiency in Seb1 resulted in widespread changes in 3' untranslated region (UTR) length as a consequence of increased alternative polyadenylation. Given that Seb1 levels affected the recruitment of conserved 3' end processing factors, our findings indicate that the conserved RNA-binding protein Seb1 cotranscriptionally controls alternative polyadenylation.

eaQTLdb: An atlas of enhancer activity quantitative trait loci across cancer types.

Enhancers are key regulatory elements that exert crucial roles in diverse biological processes, including tumorigenesis and cancer development. Active enhancers could produce transcripts termed enhancer RNAs (eRNAs), which could be used as an index of enhancer activity. Here, we present a versatile data portal, enhancer activity quantitative trait loci database (eaQTLdb; http://www.bioailab.com:3838/eaQTLdb), for exploring the effects of genetic variants on enhancer activity and prioritizing candidate variants across different cancer types. By leveraging the accumulated multiomics data, we systematically identified genetic variants which influence enhancer activity in different cancer types, termed as eaQTLs. We have linked the eaQTLs to hallmarks of cancer and patients' overall survival to illustrate their potential biological roles in cancer development and progression. Notably, eaQTLs associated with the infiltration abundance of 24 different immune cell types were identified and incorporated into eaQTLdb. In addition, we applied colocalization analyses to examine 59 complex diseases and traits to identify eaQTLs colocalized with diseases/traits GWAS signals. Overall, eaQTLdb, incorporating a rich resource for exploration of eaQTLs in different cancer types, will not only benefit users in prioritizing candidate genetic variants and enhancers, but also help researchers decipher the roles of eaQTLs in the dysregulated pathways of cancer and tumor immune microenvironment, opening new diagnostic and therapeutic avenues in precise medicine.

Baricitinib for the treatment of intestinal Behçet's disease: A pilot study.

OBJECTIVES: The pilot study aims to explore the efficacy and safety of baricitinib in treating refractory intestinal Behçet's disease (BD). METHODS: We consecutively enrolled patients with refractory intestinal BD from October 2020 to September 2022. They were treated with baricitinib 2-4 mg daily, with background glucocorticoids and immunosuppressants. Efficacy assessment included the global gastrointestinal symptom scores, the endoscopy scores, the Disease activity index for intestinal Behçet's disease (DAIBD), and the inflammatory parameters. Side effects were recorded. RESULTS: The thirteen patients (six males and seven females) had a median follow-up of eleven months, 76.92% (10/13) patients achieved complete remission of global gastrointestinal symptom scores, and 66.7% (6/9) had mucosal healing on endoscopy. The DAIBD scores decreased significantly, as well as the C-reactive protein level. Baricitinib showed a glucocorticoid-sparing effect, and the safety profile is favorable. CONCLUSION: Baricitinib might be a potential choice in treating refractory intestinal BD.

JMJD1C is required for the survival of acute myeloid leukemia by functioning as a coactivator for key transcription factors.

RUNX1-RUNX1T1 (formerly AML1-ETO), a transcription factor generated by the t(8;21) translocation in acute myeloid leukemia (AML), dictates a leukemic program by increasing self-renewal and inhibiting differentiation. Here we demonstrate that the histone demethylase JMJD1C functions as a coactivator for RUNX1-RUNX1T1 and is required for its transcriptional program. JMJD1C is directly recruited by RUNX1-RUNX1T1 to its target genes and regulates their expression by maintaining low H3K9 dimethyl (H3K9me2) levels. Analyses in JMJD1C knockout mice also establish a JMJD1C requirement for RUNX1-RUNX1T1's ability to increase proliferation. We also show a critical role for JMJD1C in the survival of multiple human AML cell lines, suggesting that it is required for leukemic programs in different AML cell types through its association with key transcription factors.

Quantitative proteomics revealed new functions of ALKBH4.

ALKBH4 is a versatile demethylase capable of catalyzing the demethylation of monomethylated lysine-84 on actin and N6 -methyladenine in DNA. In this study, we conducted a quantitative proteomic experiment to reveal the altered expression of proteins in HEK293T cells upon genetic ablation of ALKBH4. Our results showed markedly diminished levels of GSTP1 and HSPB1 proteins in ALKBH4-depleted cells, which emanate from an augmented expression level of DNA (cytosine-5)-methyltransferase 1 (DNMT1) and the ensuing elevated cytosine methylation in the promoter regions of GSTP1 and HSPB1 genes. Together, our results revealed a role of ALKBH4 in modulating DNA cytosine methylation through regulating the expression level of DNMT1 protein.

Targeted Quantitative Profiling of Epitranscriptomic Reader, Writer, and Eraser Proteins Using Stable Isotope-Labeled Peptides.

N6-Methyladenosine (m6A) and its reader, writer, and eraser (RWE) proteins assume crucial roles in regulating the splicing, stability, and translation of mRNA. Aside from m6A, RNA is known to carry many other types of chemical modifications; no systematic investigations, however, have been conducted about the crosstalk between m6A and other modified nucleosides in RNA. Here, we modified our recently established liquid chromatography-parallel-reaction monitoring (LC-PRM) method by incorporating stable isotope-labeled (SIL) peptides as internal or surrogate standards for profiling epitranscriptomic RWE proteins. We were able to detect reproducibly a total of 114 RWE proteins in HEK293T cells with the genes encoding m6A eraser proteins (i.e., ALKBH5, FTO) and the catalytic subunit of the major m6A writer complex (i.e., METTL3) being individually ablated. Notably, eight proteins, including writer proteins for 5-methylcytidine and pseudouridine, were altered by more than 1.5-fold in the opposite directions in HEK293T cells depleted of METTL3 and ALKBH5. Analysis of previously published m6A mapping results revealed the presence of m6A in the corresponding mRNAs for four of these proteins. Together, we integrated SIL peptides into our LC-PRM method for quantifying epitranscriptomic RWE proteins, and our work revealed potential crosstalks between m6A and other epitranscriptomic modifications. Our modified LC-PRM method with the use of SIL peptides should be applicable for high-throughput profiling of epitranscriptomic RWE proteins in other cell types and in tissues.

Aha1 Is an Autonomous Chaperone for SULT1A1.

The cochaperone Aha1 activates HSP90 ATPase to promote the folding of its client proteins; however, very few client proteins of Aha1 are known. With the use of an ascorbate peroxidase (APEX)-based proximity labeling method, we identified SULT1A1 as a proximity protein of HSP90 that is modulated by genetic depletion of Aha1. Immunoprecipitation followed by Western blot analysis showed the interaction of SULT1A1 with Aha1, but not HSP90. We also observed a reduced level of SULT1A1 protein upon genetic depletion of Aha1 but not upon pharmacological inhibition of HSP90, suggesting that the SULT1A1 protein level is regulated by Aha1 alone. Maturation-dependent interaction assay results showed that Aha1, but not HSP90, binds preferentially to newly synthesized SULT1A1. Reconstitution of Aha1-depleted cells with wild-type Aha1 and its E67K mutant, which is deficient in interacting with HSP90, restored SULT1A1 protein to the same level. Nonetheless, complementation of Aha1-depleted cells with an Aha1 mutant lacking the first 20 amino acids, which disrupts its autonomous chaperone function, was unable to rescue the SULT1A1 protein level. Together, our study revealed, for the first time, Aha1 as an autonomous chaperone in regulating SULT1A1. SULT1A1 is a phase-II metabolic enzyme, where it adds sulfate groups to hydroxyl functionalities in endogenous hormones and xenobiotic chemicals to improve their solubilities and promote their excretion. Thus, our work suggests the role of Aha1 cochaperone in modulating the detoxification of endogenous and environmental chemicals.

Prevalence of Helicobacter pylori Virulence Genes and Their Association with Chronic Gastritis in Beijing, China.

Helicobacter pylori is closely related to chronic gastritis. The aim of the study was to investigate the correlation between H. pylori virulence genes and chronic gastritis in order to determine the pathogenic role of H. pylori virulence genes in chronic gastritis. Gastric mucosal tissues were obtained from 142 patients with chronic gastritis at three Beijing hospitals. The presence of virulence genes was determined by polymerase chain reaction (PCR) from H. pylori DNA. Multilocus sequence typing (MLST) and a phylogenetic tree were performed to characterize the overall genetic diversity. 91 new sequence types were identified by MLST in this study, and all strains showed high genetic diversity. The H. pylori isolates were divided into three types: hspEAsia strains (61 strains), hpEurope strains (15 strains), and mixed strains (16 strains). Some virulence genes were found to be significantly different between strains. The highest positive rates were found for dupA in chronic atrophic gastritis (AG), iceA1 in chronic non-atrophic gastritis with erosions, and iceA2 in chronic non-atrophic gastritis. The presence of dupA was found to be inversely related to the risk of AG. The H. pylori strains display high genetic diversity. Some virulence genes were found to be significantly different between diseases. The detection of various virulence genes is critical for screening high-risk populations for precancerous lesions and for the early prevention and control of gastric cancer.

Complex nonlinear dynamics and vibration suppression of conceptual airfoil models: A state-of-the-art overview.

During the past few decades, several significant progresses have been made in exploring complex nonlinear dynamics and vibration suppression of conceptual aeroelastic airfoil models. Additionally, some new challenges have arisen. To the best of the author's knowledge, most studies are concerned with the deterministic case; however, the effects of stochasticity encountered in practical flight environments on the nonlinear dynamical behaviors of the airfoil systems are neglected. Crucially, coupling interaction of the structure nonlinearities and uncertainty fluctuations can lead to some difficulties on the airfoil models, including accurate modeling, response solving, and vibration suppression. At the same time, most of the existing studies depend mainly on a mathematical model established by physical mechanisms. Unfortunately, it is challenging and even impossible to obtain an accurate physical model of the complex wing structure in engineering practice. The emergence of data science and machine learning provides new opportunities for understanding the aeroelastic airfoil systems from the data-driven point of view, such as data-driven modeling, prediction, and control from the recorded data. Nevertheless, relevant data-driven problems of the aeroelastic airfoil systems are not addressed well up to now. This survey contributes to conducting a comprehensive overview of recent developments toward understanding complex dynamical behaviors and vibration suppression, especially for stochastic dynamics, early warning, and data-driven problems, of the conceptual two-dimensional airfoil models with different structural nonlinearities. The results on the airfoil models are summarized and discussed. Besides, several potential development directions that are worth further exploration are also highlighted.

Stroke 120 or FAST (Face, Arm, Speech, Time): Which is Better in Stroke Awareness Promotion for Older Residents Living in Shanghai?

BACKGROUND: To make a parallel comparison regarding the effectiveness of Stroke 120 and FAST (Face, Arm, Speech, Time) in stroke knowledge promotion among community-living older residents in Shanghai. METHODS: This is a prospective community-based study. Between 1 February 2021 and 31 July 2021, we conducted a community-based stroke education program among older residents living in two communities in Minhang district, Shanghai. Residents aged over 60 years were educated with FAST and Stroke 120 separately. We defined the community educated with FAST as FAST-Community, the other one educated with Stroke 120 as Stroke 120-Community. Pre- and post-education survey were collected. The ability to recall the meanings of FAST and Stroke 120 in pre- and post-education survey was compared. The awareness of stroke risk factors and symptoms was also compared. RESULTS: There were 466 responders in pre-education survey (231 from FAST-community, 235 from Stroke 120-community) and 456 responders in post-education survey (230 from FAST-community, 226 from Stroke 120-community). The mean age of responders in Stroke 120-community was 76 years (40% male) and in FAST-community was 71 years (52% male). Of the common stroke symptoms, we only found significant improvement in the awareness of Face drop (61.7% versus 34.6%, P<0.001) and Dizziness (45.7% versus 27.7%, P<0.001) in post-education survey for responders living in FAST-community. However, for responders living in Stroke 120-community, significant improvement was observed in all stroke symptoms (all P<0.05). As for the ability to recall the meanings of stroke awareness tools, the number of responders who can recall all the meanings of Stroke 120 increased from 0 in pre-education survey to 44 (21.5%) in post-education survey (P<0.001) for responders living in Stroke 120-community. However, among responders living in FAST-community, only 4 (5%) can recall all the meanings of FAST in post-education survey (5% versus 0%, P = 0.47). In the meantime, the proportion of responders who can recall part or all the meanings of them was also higher in Stroke 120-community in post-education survey. CONCLUSION: Among community-living older residents in Shanghai, Stroke 120 seems to be more suitable than FAST in stroke knowledge promotion.

Targeted Quantitative Profiling of GTP-Binding Proteins Associated with Metastasis of Melanoma Cells.

Metastasis is a major obstacle in the therapeutic intervention of melanoma, and several GTP-binding proteins were found to play important roles in regulating cancer metastasis. To assess systematically the regulatory roles of these proteins in melanoma metastasis, we employed a targeted chemoproteomic method, which relies on the application of stable isotope-labeled desthiobiotin-GTP acyl phosphate probes in conjunction with scheduled multiple-reaction monitoring (MRM), for profiling quantitatively the GTP-binding proteins. Following probe labeling, tryptic digestion, and affinity pull-down of desthiobiotin-conjugated peptides, differences in expression levels of GTP-binding proteins in two matched pairs of primary/metastatic melanoma cell lines were measured using liquid chromatography-MRM analysis. We also showed that among the top upregulated proteins in metastatic melanoma cells, AK4 promotes the migration and invasion of melanoma cells; overexpression of AK4 in primary melanoma cells leads to augmented migration and invasion, and reciprocally, knockdown of AK4 in metastatic melanoma cells results in repressed invasiveness. In summary, we examined the relative expression levels of GTP-binding proteins in two pairs of primary/metastatic melanoma cell lines. Our results confirmed some previously reported regulators of melanoma metastasis and revealed a potential role of AK4 in promoting melanoma metastasis.

ATF3 Modulates the Resistance of Breast Cancer Cells to Tamoxifen through an N6-Methyladenosine-Based Epitranscriptomic Mechanism.

Tamoxifen has been used for years for treating estrogen receptor-positive breast cancer; drug resistance, however, constitutes one of the main challenges for this therapy. We found that the protein expression level of ATF3 is significantly higher in tamoxifen-resistant (TamR) MCF-7 cells than the corresponding parental cancer cells. In addition, ATF3 protein expression is positively correlated with the resistance of TamR MCF-7 cells to 4-hydroxytamoxifen (4-OHT). Mechanistically, elevated ATF3 protein expression in TamR MCF-7 cells results from a lower level of expression of YTHDF2, an m6A reader protein, and the ensuing stabilization and increased translational efficiency of ATF3 mRNA. Additionally, TamR MCF-7 cells exhibited decreased methylation at A131, a consensus motif site for m6A, in the 5'-untranslated region (5'-UTR) of ATF3 mRNA. Moreover, augmented ATF3 stimulates the expression of ABCB1, an efflux pump that confers drug resistance in breast cancer cells, and ATF3 itself is also positively regulated by adenylate kinase 4. Together, our results uncovered a novel molecular target for m6A modification (i.e., ATF3 mRNA) and the epitranscriptomic regulator for this target (i.e., YTHDF2). We also illustrated the role of ATF3 in drug resistance, revealed its downstream target (i.e., ABCB1), and suggested ATF3 as a candidate therapeutic target for overcoming drug resistance in cancer cells.

Adenylate Kinase 4 Modulates the Resistance of Breast Cancer Cells to Tamoxifen through an m6A-Based Epitranscriptomic Mechanism.

N6-methyladenosine (m6A) is the most abundant internal modification in mRNA and this methylation constitutes an important regulatory mechanism for the stability and translational efficiency of mRNA. In this study, we found that the protein levels of adenylate kinase 4 (AK4) and m6A writer METTL3 are significantly higher in tamoxifen-resistant (TamR) MCF-7 cells than in parental cells. The TamR MCF-7 cells also exhibit increased methylation at multiple m6A consensus motif sites in the 5' untranslated region (5' UTR) of AK4 mRNA, and genetic depletion of METTL3 in TamR MCF-7 cells led to a diminished AK4 protein level and attenuated resistance to tamoxifen. In addition, we observed augmented levels of reactive oxygen species (ROS) and p38 activity in TamR MCF-7 cells, and both are diminished upon genetic depletion of AK4. Reciprocally, overexpression of AK4 in MCF-7 cells stimulates ROS and p38 phosphorylation levels, and it suppresses mitochondrial apoptosis. Moreover, scavenging of intracellular ROS leads to reduced p38 activity and re-sensitizes TamR MCF-7 cells to tamoxifen. Thus, our results uncover a novel m6A-mediated epitranscriptomic mechanism for the regulation of AK4, illustrate the cellular pathways through which increased AK4 expression contributes to tamoxifen resistance, and reveal AK4 as a potential therapeutic target for overcoming tamoxifen resistance.

Elevated Hexokinase II Expression Confers Acquired Resistance to 4-Hydroxytamoxifen in Breast Cancer Cells.

Tamoxifen has been clinically used in treating estrogen receptor (ER)-positive breast cancer for over 30 years. The most challenging aspect associated with tamoxifen therapy is the development of resistance in initially responsive breast tumors. We applied a parallel-reaction monitoring (PRM)-based quantitative proteomic method to examine the differential expression of kinase proteins in MCF-7 and the isogenic tamoxifen-resistant (TamR) cells. We were able to quantify the relative protein expression levels of 315 kinases, among which hexokinase 2 (HK2) and mTOR were up-regulated in TamR MCF-7 cells. We also observed that the TamR MCF-7 cells exhibited elevated rate of glycolysis than the parental MCF-7 cells. In addition, we found that phosphorylation of S6K - a target of mTOR - was much lower in TamR MCF-7 cells, and this phosphorylation level could be restored upon genetic depletion or pharmacological inhibition of HK2. Reciprocally, the level of S6K phosphorylation was diminished upon overexpression of HK2 in MCF-7 cells. Moreover, we observed that HK2 interacts with mTOR, and this interaction inhibits mTOR activity. Lower mTOR activity led to augmented autophagy, which conferred resistance of MCF-7 cells toward tamoxifen. Together, our study demonstrates that elevated expression of HK2 promotes autophagy through inhibiting the mTOR-S6K signaling pathway and results in resistance of MCF-7 breast cancer cells toward tamoxifen; thus, our results uncovered, for the first time, HK2 as a potential therapeutic target for overcoming tamoxifen resistance.