ZNF397 Deficiency Triggers TET2-driven Lineage Plasticity and AR-Targeted Therapy Resistance in Prostate Cancer

Cancer cells exhibit phenotypical plasticity and epigenetic reprogramming, which allows them to evade lineage-dependent targeted treatments by adopting lineage plasticity. The underlying mechanisms by which cancer cells exploit the epigenetic regulatory machinery to acquire lineage plasticity and therapy resistance remain poorly understood. We identified Zinc Finger Protein 397 (ZNF397) as a bona fide coactivator of the androgen receptor (AR), essential for the transcriptional program governing AR-driven luminal lineage. ZNF397 deficiency facilitates the transition of cancer cell from an AR-driven luminal lineage to a Ten-Eleven Translocation 2 (TET2)-driven lineage plastic state, ultimately promoting resistance to therapies inhibiting AR signaling. Intriguingly, our findings indicate that a TET2 inhibitor can eliminate the resistance to AR targeted therapies in ZNF397-deficient tumors. These insights uncover a novel mechanism through which prostate cancer acquires lineage plasticity via epigenetic rewiring and offer promising implications for clinical interventions designed to overcome therapy resistance dictated by lineage plasticity.

Mapping Cellular Interactions from Spatially Resolved Transcriptomics Data

Cell-cell communication (CCC) is essential to how life forms and functions. However, accurate, high-throughput mapping of how expression of all genes in one cell affects expression of all genes in another cell is made possible only recently, through the introduction of spatially resolved transcriptomics technologies (SRTs), especially those that achieve single cell resolution. However, significant challenges remain to analyze such highly complex data properly. Here, we introduce a Bayesian multi-instance learning framework, spacia, to detect CCCs from data generated by SRTs, by uniquely exploiting their spatial modality. We highlight spacia's power to overcome fundamental limitations of popular analytical tools for inference of CCCs, including losing single-cell resolution, limited to ligand-receptor relationships and prior interaction databases, high false positive rates, and most importantly the lack of consideration of the multiple-sender-to-one-receiver paradigm. We evaluated the fitness of spacia for all three commercialized single cell resolution ST technologies: MERSCOPE/Vizgen, CosMx/Nanostring, and Xenium/10X. Spacia unveiled how endothelial cells, fibroblasts and B cells in the tumor microenvironment contribute to Epithelial-Mesenchymal Transition and lineage plasticity in prostate cancer cells. We deployed spacia in a set of pan-cancer datasets and showed that B cells also participate in PDL1/PD1 signaling in tumors. We demonstrated that a CD8+ T cell/PDL1 effectiveness signature derived from spacia analyses is associated with patient survival and response to immune checkpoint inhibitor treatments in 3,354 patients. We revealed differential spatial interaction patterns between γδ T cells and liver hepatocytes in healthy and cancerous contexts. Overall, spacia represents a notable step in advancing quantitative theories of cellular communications.

Genome-wide analysis of FRF gene family and functional identification of HvFRF9 under drought stress in barley

FHY3 and its homologous protein FAR1 are the founding members of FRS family. They exhibited diverse and powerful physiological functions during evolution, and participated in the response to multiple abiotic stresses. FRF genes are considered to be truncated FRS family proteins. They competed with FRS for DNA binding sites to regulate gene expression. However, only few studies are available on FRF genes in plants participating in the regulation of abiotic stress. With wide adaptability and high stress-resistance, barley is an excellent candidate for the identification of stress-resistance-related genes. In this study, 22 HvFRFs were detected in barley using bioinformatic analysis from whole genome. According to evolution and conserved motif analysis, the 22 HvFRFs could be divided into subfamilies I and II. Most promoters of subfamily I members contained abscisic acid and methyl jasmonate response elements; however, a large number promoters of subfamily II contained gibberellin and salicylic acid response elements. HvFRF9, one of the members of subfamily II, exhibited a expression advantage in different tissues, and it was most significantly upregulated under drought stress. In-situ PCR revealed that HvFRF9 is mainly expressed in the root epidermal cells, as well as xylem and phloem of roots and leaves, indicating that HvFRF9 may be related to absorption and transportation of water and nutrients. The results of subcellular localization indicated that HvFRF9 was mainly expressed in the nuclei of tobacco epidermal cells and protoplast of arabidopsis. Further, transgenic arabidopsis plants with HvFRF9 overexpression were generated to verify the role of HvFRF9 in drought resistance. Under drought stress, leaf chlorosis and wilting, MDA and O2 - contents were significantly lower, meanwhile, fresh weight, root length, PRO content, and SOD, CAT and POD activities were significantly higher in HvFRF9-overexpressing arabidopsis plants than in wild-type plants. Therefore, overexpression of HvFRF9 could significantly enhance the drought resistance in arabidopsis. These results suggested that HvFRF9 may play a key role in drought resistance in barley by increasing the absorption and transportation of water and the activity of antioxidant enzymes. This study provided a theoretical basis for drought resistance in barley and provided new genes for drought resistance breeding.

UBE2J1 is the E2 ubiquitin-conjugating enzyme regulating androgen receptor degradation and antiandrogen resistance

Prostate cancer (PCa) is primarily driven by aberrant Androgen Receptor (AR) signaling. Although there has been substantial advancement in antiandrogen therapies, resistance to these treatments remains a significant obstacle, often marked by continuous or enhanced AR signaling in resistant tumors. While the dysregulation of the ubiquitination-based protein degradation process is instrumental in the accumulation of oncogenic proteins, including AR, the molecular mechanism of ubiquitination-driven AR degradation remains largely undefined. We identified UBE2J1 as the critical E2 ubiquitin-conjugating enzyme responsible for guiding AR ubiquitination and eventual degradation. The absence of UBE2J1, found in 5-15% of PCa patients, results in disrupted AR ubiquitination and degradation. This disruption leads to an accumulation of AR proteins, promoting resistance to antiandrogen treatments. By employing a ubiquitination-based AR degrader to adeptly restore AR ubiquitination, we reestablished AR degradation and inhibited the proliferation of antiandrogen-resistant PCa tumors. These findings underscore the fundamental role of UBE2J1 in AR degradation and illuminate an uncharted mechanism through which PCa maintains heightened AR protein levels, fostering resistance to antiandrogen therapies.

Effects of miR-204-5p and Target Gene EphB2 on Cognitive Impairment Induced by Aluminum Exposure in Rats

Aluminum is a common environmental neurotoxin. Aluminum ions can cross the blood-brain barrier and accumulate in different brain regions, damage brain tissue, and cause cognitive impairment, but the molecular mechanism of aluminum neurotoxicity is not precise. This study investigated the effects of miR-204-5p, target gene EphB2, and downstream signaling pathway NMDAR-ERK-CREB-Arc on cognitive dysfunction induced by aluminum exposure. The results showed that the learning and memory of the rats were impaired in behavior. The accumulation of aluminum in the hippocampus resulted in the damage of nerve cell morphology in the CA1 region of the hippocampus. The expression level of miR-204-5p was increased, and the mRNA and protein expressions of EphB2, NMDAR2B, ERK1/2, CREB, and Arc were decreased. The results indicated that the mechanism of impaired learning and memory induced by aluminum exposure might promote the expression of miR-204-5P and further inhibit the expression of the target gene EphB2 and its downstream signaling pathway NMDAR-ERK-CREB-Arc.

ZNF397 Loss Triggers TET2-driven Epigenetic Rewiring, Lineage Plasticity, and AR-targeted Therapy Resistance in AR-dependent Cancers

Cancer cells exhibit phenotypical plasticity and epigenetic reprogramming, which allows them to evade lineage-dependent targeted treatments by adopting lineage plasticity. The underlying mechanisms by which cancer cells exploit the epigenetic regulatory machinery to acquire lineage plasticity and therapy resistance remain poorly understood. We identified Zinc Finger Protein 397 (ZNF397) as a bona fide co-activator of the androgen receptor (AR), essential for the transcriptional program governing AR-driven luminal lineage. ZNF397 deficiency facilitates the transition of cancer cell from an AR-driven luminal lineage to a Ten-Eleven Translocation 2 (TET2)-driven lineage plastic state, ultimately promoting resistance to therapies inhibiting AR signaling. Intriguingly, our findings indicate that TET2 inhibitor can eliminate the AR targeted therapies resistance in ZNF397-deficient tumors. These insights uncover a novel mechanism through which prostate and breast cancers acquire lineage plasticity via epigenetic rewiring and offer promising implications for clinical interventions designed to overcome therapy resistance dictated by lineage plasticity.

Statement of Significance

This study reveals a novel epigenetic mechanism regulating tumor lineage plasticity and therapy response, enhances understanding of drug resistance and unveils a new therapeutic strategy for prostate cancer and other malignancies. Our findings also illuminate TET2's oncogenic role and mechanistically connect TET2-driven epigenetic rewiring to lineage plasticity and therapy resistance.

The Critical Interplay of CAF Plasticity and Resistance in Prostate Cancer

Prostate cancer is a common malignancy driven by the androgen receptor (AR) pathway, with androgen deprivation therapy (ADT) being a standard treatment. However, the development of castration-resistant prostate cancer (CRPC) poses a significant challenge. CRPC is characterized by significantly increased tumor heterogeneity and lineage plasticity. Current research has primarily emphasized intrinsic tumor mechanisms, paying less attention to the role of the tumor microenvironment in cancer recurrence and drug resistance. In their recent study published in Cancer Cell, Wang and colleagues used single-cell RNA sequencing in genetically engineered mouse models with prostate tumors at different stages. They revealed that SPP1+ myofibroblastic cancer-associated fibroblasts (myCAF), induced by ADT, play an instrumental role in CRPC development. Their work also underscores the association between therapy-induced phenotypic alterations of CAFs and disease progression. This discovery highlights the potential for stromal compartment targeting as a means to mitigate CRPC development and overcome treatment resistance.

Loss of SYNCRIP unleashes APOBEC-driven mutagenesis, tumor heterogeneity, and AR-targeted therapy resistance in prostate cancer

Tumor mutational burden and heterogeneity has been suggested to fuel resistance to many targeted therapies. The cytosine deaminase APOBEC proteins have been implicated in the mutational signatures of more than 70% of human cancers. However, the mechanism underlying how cancer cells hijack the APOBEC mediated mutagenesis machinery to promote tumor heterogeneity, and thereby foster therapy resistance remains unclear. We identify SYNCRIP as an endogenous molecular brake which suppresses APOBEC-driven mutagenesis in prostate cancer (PCa). Overactivated APOBEC3B, in SYNCRIP-deficient PCa cells, is a key mutator, representing the molecular source of driver mutations in some frequently mutated genes in PCa, including FOXA1, EP300. Functional screening identifies eight crucial drivers for androgen receptor (AR)-targeted therapy resistance in PCa that are mutated by APOBEC3B: BRD7, CBX8, EP300, FOXA1, HDAC5, HSF4, STAT3, and AR. These results uncover a cell-intrinsic mechanism that unleashes APOBEC-driven mutagenesis, which plays a significant role in conferring AR-targeted therapy resistance in PCa.

Abstract 3891: Epigenetic rewiring promotes antiandrogen resistance and metastasis via heterogenous oncogenic drivers in prostate cancer

Prostate cancer (PCa) is the most diagnosed cancer among American men, which has traditionally been treated through hormone therapy. However, after hormone therapy many patients with PCa still develop a more aggressive stage of PCa, called metastasis castration resistant prostate cancer (mCRPC). The second- generation antiandrogens, such as enzalutamide or apalutamide, are used to competitively inhibit the androgen receptor (AR) signaling and achieved great clinical success. However, most of the mCRPC patients would develop resistance to the targeted therapy drugs within 6 months to 2 years after initial administration. Consequently, understanding the molecular mechanism of antiandrogen resistance, has become a critical endeavor to provide a greater benefit to patients. mCRPC is characterized by extensive heterogeneity of genomic copy number alterations, which may lead to antiandrogen resistance. TP53 and RB1 alterations have been reported to be dramatically enriched in mCRPC neuroendocrine cancer and we have previously found that inactivation of both TP53 and RB1 confers resistance to antiandrogen through lineage plasticity, where cancer cells can transdifferentiate from a luminal lineage to a mixture of basal and neuroendocrine lineages, which is no longer dependent on AR signaling. Despite these exciting discoveries, only 10% of patients have TP53 and RB1 loss and it is estimated that approximately 40% of patients develop antiandrogen resistance through an undiscovered mechanism.To identify more genomic alterations which confer antiandrogen resistance, we performed an in vivo library screening and identified some of the frequently depleted genes as top candidates mediating antiandrogen response, including the chromatin helicase DNA-binding factor (CHD1). Strikingly, the loss of CHD1 establishes an altered chromatin landscape and enables the activation of heterogenous resistant subclones to emerge, including clones with ectopic NR3C1/GR, POU3F2/BRN2, TBX2, and NR2F1. This work provided an innovative model to explain the dramatically increased tumor heterogeneity in therapy resistant prostate cancer and suggested potential druggable targets to overcome resistance. Building on those exciting results, we are now examining the underlying mechanism how the epigenetic rewiring in resistant tumor clones confer resistance and monitoring the evolution of those heterogenous resistant subclones. Furthermore, we are revealing the collaborative function of those four resistant driver genes in promoting metastasis to various distal organs through multidisplinary approaches including single cell transcriptomics and 3D organoid modeling. The completion of this study will not only add clarity to the mechanism of antiandrogen resistance but may also lead to the development of novel biomarker and therapeutic approaches to overcome resistance.

Citation Format: Xiaong li, Su Deng, Julisa Gonzalez, Carla Rodriguez Tirado, Choushi Wang, Nickolas A. Johnson, Lauren Metang, Ping Mu. Epigenetic rewiring promotes antiandrogen resistance and metastasis via heterogenous oncogenic drivers in prostate cancer. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3891.

DRR1 promotes neuroblastoma cell differentiation by regulating CREB expression

BACKGROUND

Neuroblastoma is the most common cancer in infants and the most common extracranial solid tumor in childhood. DRR1 was identified to be downregulated in poorly differentiated ganglion cells from neuroblastoma model mice. However, the roles of DRR1 in neuroblastoma remain largely unclear.

METHODS

The neuroblastoma cells were induced to differentiate, and the expression of DRR1 was detected. The expression of the neuroblastoma cell differentiation markers was analyzed in DRR1 shRNA- or DRR1-expressing vector-treated neuroblastoma cells. The downstream genes of DRR1 were screened with ChIP-seq assay. Finally, TNB1 cells were infected with DRR1 shRNA and CREB expressing vector containing lentivirus, and the expression of the cell differentiation markers, cell cycle distribution and tumor growth were analyzed.

RESULTS

The expression of DRR1 was increased in differentiated neuroblastoma cells, and downregulation of DRR1 expression inhibited the differentiation of neuroblastoma cells. Further experiments indicated that CREB is a candidate downstream gene of DRR1, and it mediates neuroblastoma cell differentiation. Moreover, overexpression of CREB rescued the effect of DRR1 shRNA on cell differentiation, cell cycle distribution and tumor growth in neuroblastoma.

CONCLUSIONS

DRR1-CREB axis modulates the differentiation of neuroblastoma cells and is associated with the outcome of neuroblastoma patients.

IMPACT

DRR1 is involved in regulation of the differentiation of neuroblastoma. Binding with actin is essential for DRR1 to regulate neuroblastoma cell differentiation. CREB is a candidate downstream gene of DRR1 in regulating of the differentiation of neuroblastoma.

Selective Nanoblocker of Cellular Stress Response for Improved Drug-Free Tumor Therapy

Nanotechnology-based drug-free therapeutic systems using external stimuli can avoid the inherent side effects of drugs and become an attractive therapeutic strategy. However, the cellular stress responses (CSR) are activated encounter with external stimuli, which greatly weaken the efficacy of the drug-free antitumor. Thus, this work proposes a CSR regulation strategy and synthesizes the glucose oxidase (GOx)-modified Cu₃ BiS₃ nanosheets (CBSG NSs) encapsulated by calcium carbonate (CBSG@CaCO₃ ) as the novel drug-free nanoagent. The CBSG@CaCO₃ not only cause external stimuli such as energy consumption and oxidative stress damage, but also can destroy the CSR mechanism to guarantee optimal efficacy of starvation-chemodynamic therapy (ST-CDT). In tumor cells, the CaCO₃ shell layer of CBSG@CaCO₃ is rapidly degraded, releasing the slowly degradable CBSG NSs with NIR-II photothermal properties that accelerate the production of external stimuli under laser irradiation. Meanwhile, CaCO₃ can block CSR to disrupt the adaptive viability of cancer cells by inhibiting expression of P27 and NRF2. Importantly, the CSR regulation achieves selective treatment on tumor cells based on the difference in physiological conditions between cancer cells and normal cells. This drug-free cancer therapy with selectivity improves the problem of poor efficacy under the action of CSR, which offers a new avenue in the cancer-related disease treatment.

Ectopic JAK–STAT activation enables the transition to a stem-like and multilineage state conferring AR-targeted therapy resistance

Emerging evidence indicates that various cancers can gain resistance to targeted therapies by acquiring lineage plasticity. Although various genomic and transcriptomic aberrations correlate with lineage plasticity, the molecular mechanisms enabling the acquisition of lineage plasticity have not been fully elucidated. We reveal that Janus kinase (JAK)–signal transducer and activator of transcription (STAT) signaling is a crucial executor in promoting lineage plasticity-driven androgen receptor (AR)-targeted therapy resistance in prostate cancer. Importantly, ectopic JAK–STAT activation is specifically required for the resistance of stem-like subclones expressing multilineage transcriptional programs but not subclones exclusively expressing the neuroendocrine-like lineage program. Both genetic and pharmaceutical inhibition of JAK–STAT signaling resensitizes resistant tumors to AR-targeted therapy. Together, these results suggest that JAK–STAT are compelling therapeutic targets for overcoming lineage plasticity-driven AR-targeted therapy resistance.

Identification of the glutamine synthetase (GS) gene family in four wheat species and functional analysis of Ta4D.GSe in Arabidopsis thaliana

Drought stress can negatively impact crop yield and quality. Improving wheat yields under drought stress is a major objective of agronomic research. Glutamine synthetase (GS) is a key enzyme of nitrogen metabolism that is critical to plant growth and development in abiotic stress response. However, to date, no systemic characterization of the GS genes has yet been conducted in wheat and its close relatives. We identified a total of 15 GS genes in Triticum aestivum (2n = 6x = 42; AABBDD), as well as 9 GS genes in Triticum dicoccoides (2n = 4x = 28; AABB), 6 in Aegilops tauschii (2n = 2x = 14; DD), and 5 in Triticum urartu (2n = 2x = 14; AA). The 35 GSs were further clustered into five lineages according to the phylogenetic tree. Synteny analysis revealed that the three subgenomes in bread wheat retained extensive synteny between bread wheat and its three relative species. We identified three up-regulated TaGSs (Ta4A.GSe, Ta4B.GSe, and Ta4D.GSe) from transcriptome data after drought and salt stress. Ta4D.GSe was subsequently used for further functional studies, and its subcellular localization were determined in Arabidopsis protoplasts. Its overexpression in Arabidopsis enhanced drought tolerance by increasing the ability of scavenging of reactive oxygen species (ROS) and osmotic adjustment. We identified GS gene family in four wheat species and performed comparative analyses of their relationships, chromosome locations, conserved motif, gene structure, and synteny. The subcellular localization of Ta4D.GSe was detected and its drought tolerance function was demonstrated. Taken together, these findings provide insight into the potential functional roles of the GS genes in abiotic stress tolerance. KEY MESSAGE: This report clearly shows detailed characterization of GS gene family in four wheat species and demonstrates that Ta4D.GSe plays an important role in enhancing drought tolerance by improving the scavenging of ROS and osmotic adjustment ability in Arabidopsis.

The driver role of JAK-STAT signalling in cancer stemness capabilities leading to new therapeutic strategies for therapy- and castration-resistant prostate cancer

BACKGROUND

Lineage plasticity in prostate cancer (PCa) has emerged as an important mechanism leading to the onset of therapy- and castration-resistant PCa (t-CRPC), which is closely associated with cancer stem cell (CSC) activity. This study is to identify critical driver(s) with mechanism of action and explore new targeting strategy.

METHODS

Various PCa cell lines with different genetic manipulations were subjected to in vitro prostasphere assay, cell viability assay and in vivo stemness potential. In addition, bioinformatic analyses such as Ingenuity pathway and Gene Set Enrichment Analysis were carried out to determine clinical relevance. The in vivo anti-tumour activity of JAK or STAT1 inhibitors was examined in clinically relevant t-CRPC model.

RESULTS

We demonstrated the role of interferon-related signalling pathway in promoting PCa stemness, which correlated with significant elevation of interferon related DNA damage resistance signature genes in metastatic PCa. Inhibition of JAK-STAT1 signalling suppresses the in vitro and in vivo CSC capabilities. Mechanistically, IFIT5, a unique downstream effector of JAK-STAT1 pathway, can facilitate the acquisition of stemness properties in PCa by accelerating the turnover of specific microRNAs (such as miR-128 and -101) that can target several CSC genes (such as BMI1, NANOG, and SOX2). Consistently, knocking down IFIT5 in t-CRPC cell can significantly reduce in vitro prostasphere formation as well as decrease in vivo tumour initiating capability.

CONCLUSIONS

This study provides a critical role of STAT1-IFIT5 in the acquisition of PCSC and highlights clinical translation of JAK or STAT1 inhibitors to prevent the outgrowth of t-CRPC.

SIRT1 Is Involved in the Neuroprotection of Pterostilbene Against Amyloid β 25-35-Induced Cognitive Deficits in Mice

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by amyloid-β (Aβ) deposits and neurofibrillary tangles. Pterostilbene (PTE), a bioactive component mainly in blueberries, is found to have neuroprotective properties. However, the specific underlying mechanisms of PTE in protecting AD remain unclear. Herein, we explored its effects on Aβ25-35-induced neuronal damage in vivo and in vitro and further compared the roles with its structural analog resveratrol (RES) in improving learning-memory deficits. We found that intragastric administration of PTE (40 mg/kg) displayed more effective neuroprotection on Aβ25-35-induced cognitive dysfunction assessed using the novel object test, Y-maze test, and Morris water maze test. Then, we found that PTE improved neuronal plasticity and alleviated neuronal loss both in vivo and in vitro. Additionally, PTE upregulated the expression of sirtuin-1 (SIRT1) and nuclear factor erythroid 2-related factor 2 (Nrf2) and the level of superoxide dismutase (SOD), and inhibited mitochondria-dependent apoptosis in the Aβ25-35-treated group. However, SIRT1 inhibitor EX527 reversed the neuroprotection and induced a drop in mitochondrial membrane potential in PTE-treated primary cortical neurons. Our data suggest that PTE's enhancing learning-memory ability and improving neuroplasticity might be related to inhibiting mitochondria-dependent apoptosis via the antioxidant effect regulated by SIRT1/Nrf2 in AD.

Assessment of the Causal Effects of Obstructive Sleep Apnea on Atrial Fibrillation: A Mendelian Randomization Study

Background

Obstructive sleep apnea (OSA) and atrial fibrillation (AF) are epidemiologically correlated, but the causal relationship between them remains elusive. We aimed to explore the causal relationships between OSA and AF.

Method

Using both the Finnish biobank and publicly available genome-wide association study data (GWAS), we conducted a two-sample Mendelian randomization (MR) analysis to estimate the causal effect of OSA on AF, both in the primary analysis and replicated analysis. The inverse variance weighted MR was selected as the main method. To further test the independent causal effect of OSA on AF, we also performed multivariable MR (MVMR), adjusting for body mass index (BMI), hypertension, and coronary artery disease (CAD), respectively.

Results

In the primary analysis, OSA was significantly associated with the increased risk of AF (OR 1.21, 95% CI 1.11–1.32) and the replicated analysis showed consistent results (OR 1.17, 95% CI 1.05–1.30). Besides, there was no heterogeneity and horizontal pleiotropy observed both in the primary and replicated analysis. Further multivariable MR suggested that the causal relationships between OSA and AF exist independently of BMI and CAD. The MVMR result after the adjustment for hypertension is similar in magnitude and direction to the univariable MR. But it did not support a causal relationship between OSA and AF.

Conclusion

Our study found that genetically driven OSA causally promotes AF. This causal relationship sheds new light on taking effective measures to prevent and treat OSA to reduce the risk of AF.

Photocatalytic H2O2 production and removal of Cr (VI) via a novel Lu3NbO7: Yb, Ho/CQDs/AgInS2/In2S3 heterostructure with broad spectral response

The low-usage of solar energy and the sluggish separation efficiency of the photogenerated electrons/holes pairs are the obstacles in the practical application of photocatalysts. The integration of upconversion and Z-scheme heterojunction is expected to break the barriers to achieve the efficient charge separation and broaden near-infrared light absorption. Herein, an effective indirect Z scheme AgInS₂/In₂S₃ heterostructure with carbon quantum dots (CQDs, as the electron conduction medium) and Lu₃NbO₇:Yb, Ho (as upconversion function) has been successfully synthesized. Consequently, the Lu₃NbO₇: Yb, Ho/CQDs/AgInS₂/In₂S₃ heterostructure exhibited superior photocatalytic activities for Cr(VI) reduction and H₂O₂ production, reducing 99.9% of Cr(VI)(20 ppm, 15 min) and 78.5% of Cr(VI) (40 ppm, 30 min) with visible light irradiation as well as 94.0% of Cr(VI) (20 ppm, 39 min) under NIR light irradiation. Simultaneously, the heterostructure could generate 902.9 μM H₂O₂ for 5 h under visible light irradiation. The intensive photocatalytic properties could primarily be attributed to the boosted light absorption capacity, the improved solar-to-energy conversion by the remarkable upconversion capacity of Lu₃NbO₇: Yb, Ho/CQDs and the faster charge transfer through a Z-schematic pathway. This work is anticipated to open a novel "window" for designing the efficient photocatalysts by coupling of Lu₃NbO₇: Yb, Ho and CQDs.

SOX2 mediates metabolic reprogramming of prostate cancer cells

New strategies are needed to predict and overcome metastatic progression and therapy resistance in prostate cancer. One potential clinical target is the stem cell transcription factor SOX2, which has a critical role in prostate development and cancer. We thus investigated the impact of SOX2 expression on patient outcomes and its function within prostate cancer cells. Analyses of SOX2 expression among a case-control cohort of 1028 annotated tumor specimens demonstrated that SOX2 expression confers a more rapid time to metastasis and decreased patient survival after biochemical recurrence. SOX2 ChIP-Seq analyses revealed SOX2-binding sites within prostate cancer cells which differ significantly from canonical embryonic SOX2 gene targets, and prostate-specific SOX2 gene targets are associated with multiple oncogenic pathways. Interestingly, phenotypic and gene expression analyses after CRISPR-mediated deletion of SOX2 in castration-resistant prostate cancer cells, as well as ectopic SOX2 expression in androgen-sensitive prostate cancer cells, demonstrated that SOX2 promotes changes in multiple metabolic pathways and metabolites. SOX2 expression in prostate cancer cell lines confers increased glycolysis and glycolytic capacity, as well as increased basal and maximal oxidative respiration and increased spare respiratory capacity. Further, SOX2 expression was associated with increased quantities of mitochondria, and metabolomic analyses revealed SOX2-associated changes in the metabolism of purines, pyrimidines, amino acids and sugars, and the pentose phosphate pathway. Analyses of SOX2 gene targets with central functions metabolism (CERK, ECHS1, HS6SDT1, LPCAT4, PFKP, SLC16A3, SLC46A1, and TST) document significant expression correlation with SOX2 among RNA-Seq datasets derived from patient tumors and metastases. These data support a key role for SOX2 in metabolic reprogramming of prostate cancer cells and reveal new mechanisms to understand how SOX2 enables metastatic progression, lineage plasticity, and therapy resistance. Further, our data suggest clinical opportunities to exploit SOX2 as a biomarker for staging and imaging, as well as a potential pharmacologic target.

MYCN directly targets NeuroD1 to promote cellular proliferation in neuroblastoma

NeuroD1 is a neuronal differentiation factor that contains a basic helix-loop-helix (bHLH) motif. Recently, NeuroD1 was found to be associated with tumorigenesis in neuroblastoma (NB), and is known to promote cell proliferation and migration in these cells. Here, we found that MYCN regulates the expression of NeuroD1 in NB cells, and that the downregulation of MYCN using short hairpin RNAs (shRNA) results in the inhibition of cellular proliferation in NB cells. Moreover, the phenotype induced by MYCN shRNA was rescued by the exogenous expression of NeuroD1. Chromatin immunoprecipitation (ChIP) assay showed that MYCN directly binds to the E-box element in the NeuroD1 promoter region. In addition, our evaluation of two clinical databases showed that there was a positive correlation between the expression of MYCN and NeuroD1 in NB patients, which supports our in vitro data. In conclusion, this study demonstrates that MYCN-regulated NeuroD1 expression is one of the important mechanisms underlying enhanced cellular proliferation induced by the increase of MYCN expression in NB, and our results provide an important therapeutic target for NB in the future.

Smoking, DNA Methylation, and Breast Cancer: A Mendelian Randomization Study

Background

Smoking was strongly associated with breast cancer in previous studies. Whether smoking promotes breast cancer through DNA methylation remains unknown.

Methods

Two-sample Mendelian randomization (MR) analyses were conducted to assess the causal effect of smoking-related DNA methylation on breast cancer risk. We used 436 smoking-related CpG sites extracted from 846 middle-aged women in the ARIES project as exposure data. We collected summary data of breast cancer from one of the largest meta-analyses, including 69,501 cases for ER+ breast cancer and 21,468 cases for ER- breast cancer. A total of 485 single-nucleotide polymorphisms (SNPs) were selected as instrumental variables (IVs) for smoking-related DNA methylation. We further performed an MR Steiger test to estimate the likely direction of causal estimate between DNA methylation and breast cancer. We also conducted colocalization analysis to evaluate whether smoking-related CpG sites shared a common genetic causal SNP with breast cancer in a given region.

Results

We established four significant associations after multiple testing correction: the CpG sites of cg2583948 [OR = 0.94, 95% CI (0.91-0.97)], cg0760265 [OR = 1.07, 95% CI (1.03-1.11)], cg0420946 [OR = 0.95, 95% CI (0.93-0.98)], and cg2037583 [OR =1.09, 95% CI (1.04-1.15)] were associated with the risk of ER+ breast cancer. All the four smoking-related CpG sites had a larger variance than that in ER+ breast cancer (all p < 1.83 × 10^-11) in the MR Steiger test. Further colocalization analysis showed that there was strong evidence (based on PPH4 > 0.8) supporting a common genetic causal SNP between the CpG site of cg2583948 [with IMP3 expression (PPH4 = 0.958)] and ER+ breast cancer. There were no causal associations between smoking-related DNA methylation and ER- breast cancer.

Conclusions

These findings highlight potential targets for the prevention of ER+ breast cancer. Tissue-specific epigenetic data are required to confirm these results.

Cd0.5Zn0.5S/CoWO4 Nanohybrids with a Twinning Homojunction and an Interfacial S-Scheme Heterojunction for Efficient Visible-Light-Induced Photocatalytic CO2 Reduction

The construction of a phase junction photocatalyst can significantly enhance the photocatalytic performance with high selectivity for CO₂ reduction. In this study, an S-scheme junction Cd_0.5Zn_0.5S/CoWO₄ semiconductor with the coupling of a twin crystal Cd_0.5Zn_0.5S homojunction and CoWO₄ was designed through a hydrothermal method, which could convert CO₂ to CO with high efficiency under visible-light illumination. Cd_0.5Zn_0.5S-10%CoWO₄ exhibited the optimal performance and its CO yield and selectivity were up to 318.68 μmol·g^-1 and 95.90%, respectively, which were 4.54 and 1.62 times higher than that of twin crystal Cd_0.5Zn_0.5S. Moreover, the Cd_0.5Zn_0.5S homojunction with a zinc-blende and wurtzite phase and the S-scheme phase junction of Cd_0.5Zn_0.5S/CoWO₄ enhanced the property of CO₂ adsorption and accelerated the detachment of photogenerated carriers. The combination of photogenerated holes in Cd_0.5Zn_0.5S and the electrons of CoWO₄ can retain the reduction sites to improve photocatalytic performance. This study provides a neoteric concept and reference for the construction of the S-scheme phase junction.

High-Throughput Sequencing-Based Identification of miRNAs and Their Target mRNAs in Wheat Variety Qing Mai 6 Under Salt Stress Condition

Soil salinization is one of the major abiotic stresses that adversely affect the yield and quality of crops such as wheat, a leading cereal crop worldwide. Excavating the salt-tolerant genes and exploring the salt tolerance mechanism can help breeding salt-tolerant wheat varieties. Thus, it is essential to identify salt-tolerant wheat germplasm resources. In this study, we carried out a salt stress experiment using Qing Mai 6 (QM6), a salt-tolerant wheat variety, and sequenced the miRNAs and mRNAs. The differentially expressed miRNAs and mRNAs in salt stress conditions were compared with the control. As results, a total of eight salt-tolerance-related miRNAs and their corresponding 11 target mRNAs were identified. Further analysis revealed that QM6 enhances salt tolerance through increasing the expression level of genes related to stress resistance, antioxidation, nutrient absorption, and lipid metabolism balance, and the expression of these genes was regulated by the identified miRNAs. The resulting data provides a theoretical basis for future research studies on miRNAs and novel genes related to salt tolerance in wheat in order to develop genetically improved salt-tolerant wheat varieties.

Downregulated in renal carcinoma 1 (DRR1) mediates the differentiation of neural stem cells through transcriptional regulation

Downregulated in renal carcinoma 1 (DRR1), also called family with sequence similarity 107, member A (FAM107A), is highly expressed in the nervous system. DRR1 has been found to be involved in neuronal survival, spine formation, and synaptic function. Recently, several studies have reported that DRR1 is expressed in neural stem cells (NSCs) and neural progenitor cells during the early stages of brain development. However, the mechanisms underlying the role and function of DRR1 in NSCs are poorly understood. To clarify the role of DRR1 in NSCs, we transfected DRR1 shRNA into primary NSCs and found that downregulation of DRR1 suppressed the differentiation of NSCs. To investigate the underlying mechanism in this case, chromatin immunoprecipitation sequencing (ChIP-seq) analysis was performed to identify the genes downstream of DRR1. Several genes, such as AHNAK, VAMP8, NOD1, and ACVR2B were identified to be downstream of DRR1 in NSCs.

Amyloid-β (25-35) regulates neuronal damage and memory loss via SIRT1/Nrf2 in the cortex of mice

Alzheimer's disease (AD) is the most common type of dementia. AD is pathologically characterized by synaptic dysfunction and cognitive decline due to the aggregation of a large amount of amyloid-β (Aβ) protein in the brain. However, recent studies have discovered that the Aβ is produced as an antimicrobial peptide that acts against bacteria and viruses. This has renewed interest in the effect of Aβ on AD. Thus, in this study, we investigated the different concentrations of Aβ_25-35 on neuroprotection and further explore the related mechanisms. Firstly, we detected the cognitive function using the Y-maze test, novel object recognition memory task and Morris water maze test. Then, we analyzed the ultrastructure of synapses and mitochondria, in addition to evaluating SOD levels. We also examined the effect of Aβ_25-35 on the viability and structure of the primary neurons. The western blot analysis was used to measure the protein levels. The results showed that mice treated with high concentration of Aβ_25-35 impaired the learning-memory ability and disordered the structure of neurons and mitochondria. Meanwhile, high concentration of Aβ_25-35 decreased the SIRT1/Nrf2 related antioxidant capacity and induced apoptosis. In contrast, mice treated with low concentration of Aβ_25-35 increased SOD levels and SIRT1/Nrf2 expressions, and induced autophagy. Our data suggest that low concentration of Aβ_25-35 may increase SOD levels through SIRT1/Nrf2 and induce autophagy.

Overcoming oncogene addiction in breast and prostate cancers: a comparative mechanistic overview

Prostate cancer (PCa) and breast cancer (BCa) are both hormone-dependent cancers that require the androgen receptor (AR) and estrogen receptor (ER, ESR1) for growth and proliferation, respectively. Endocrine therapies that target these nuclear receptors (NRs) provide significant clinical benefit for metastatic patients. However, these therapeutic strategies are seldom curative and therapy resistance is prevalent. Because the vast majority of therapy-resistant PCa and BCa remain dependent on the augmented activity of their primary NR driver, common mechanisms of resistance involve enhanced NR signaling through overexpression, mutation, or alternative splicing of the receptor, coregulator alterations, and increased intracrine hormonal synthesis. In addition, a significant subset of endocrine therapy-resistant tumors become independent of their primary NR and switch to alternative NR or transcriptional drivers. While these hormone-dependent cancers generally employ similar mechanisms of endocrine therapy resistance, distinct differences between the two tumor types have been observed. In this review, we compare and contrast the most frequent mechanisms of antiandrogen and antiestrogen resistance, and provide potential therapeutic strategies for targeting both advanced PCa and BCa.

Effect of size and crystalline phase of TiO2 nanotubes on cell behaviors: A high throughput study using gradient TiO2 nanotubes

The research of TiO2 nanotubes (TNTs) in the field of biomedicine has been increasingly active. However, given the diversity of the nanoscale dimension and controversial reports, our understanding of the structure-property relationships of TNTs is not yet complete. In this paper, gradient TNTs with a wide diameter range of 20-350 nm were achieved by bipolar electrochemistry and utilized for a thorough high-throughput study of the effect of nanotube dimension and crystalline phase on protein adsorption and cell behaviors. Results indicated that protein adsorption escalated with nanotube dimension whereas cell proliferation and differentiation are preferred on small diameter (<70 nm) nanotubes. Large diameter anatase nanotubes had higher adsorption of serum proteins than as-prepared ones. But only as-prepared small diameter nanotubes presented slightly higher cell proliferation than corresponding annealed nanotubes whereas there was no discernible difference between as-prepared and annealed nanotubes on cell differentiation for the entire gradient. Those findings replenish previous research about how cell responses to TNTs with a wide diameter range and provide scientific guidance for the optimal design of biomedical materials.

Abstract PO-117: CHD1-loss promotes tumor heterogeneity and therapy resistance in prostate cancer

Targeted therapies for driver oncogenes have transformed the management of many cancers but the magnitude and duration of response remains variable. One potential explanation for the various response is the presence of additional genomic alterations which modify the degree of dependence on the targeted driver mutation. Metastatic castration resistant prostate cancer (mCRPC) serves as an example, where the target is the androgen receptor (AR). Compared to primary disease, mCRPC is characterized by extensive heterogeneity at both genomic and transcriptional levels, including genomic copy number alterations (CNAs), which are presumed to contribute to the resistance to AR targeted therapies. To gain functional insight into the genes impacted by the copy number alterations in mCRPC, we screened 730 genes often deleted in prostate cancer for CNAs that confer in vivo resistance and identified the chromodomain helicase DNA-binding protein 1 (CHD1) as a top candidate modifying resistance, a finding supported by patient data showing that CHD1 expression is inversely correlated with clinical benefit from therapy. Depletion of CHD1 in multiple human prostate cancer cell lines confers significant resistance to enzalutamide both in vitro and in vivo. Furthermore, we observed global changes in open and closed chromatin after the depletion of CHD1, indicative of an altered chromatin state, with associated changes in gene expression. Integrative analysis of ATAC-seq and RNA-seq, combining with CRISPR-based screen, identified four heterogenous resistance drivers (GR, BRN2, NR2F1, TBX2), which are elevated in different independently derived, enzalutamide-resistant, CHD1-deleted subclones. Importantly, significantly increased transcriptional heterogeneity was observed in these CHD1-depleted resistant tumors and in the tumor samples from a large mCRPC patients’ cohort. Finally, GR inhibition restored the enzalutamide sensitiivty in resistant tumors with elevated GR signaling. These results suggest CHD1-loss, through global effects on chromatin, establishes a state of plasticity that accelerates the development of AR targeted therapy resistance through activation of heterogeneous downstream effectors, which mediated the transition away from luminal lineage identity and AR dependency. This model not only provides an innovative explanation for the significantly increased transcriptional heterogeneity observed in mCRPC patients, but also suggests that proper clinical interventions targeting these heterogenous resistance drivers may be a novel avenue to prevent or even reverse resistance towards AR targeted therapies.

Citation Format: Zeda Zhang, Chuanli Zhou, Xiaoling Li, Charles Sawyers, Ping Mu. CHD1-loss promotes tumor heterogeneity and therapy resistance in prostate cancer [abstract]. In: Proceedings of the AACR Virtual Special Conference on Tumor Heterogeneity: From Single Cells to Clinical Impact; 2020 Sep 17-18. Philadelphia (PA): AACR; Cancer Res 2020;80(21 Suppl):Abstract nr PO-117.

Abstract 6028: Interferon induces lineage plasticity of castration-resistant prostate cancer

Prostate cancer (PCa) remains to be the leading cause of cancer incidence in men of the United States. Up to date, androgen deprivation therapy (ADT) remained to be the primary strategy for advanced PCa. Despite drugs targeting androgen receptor (AR) are initially effective for PCa, the disease ultimately recurs to the end stage of castration-resistant PCa (CRPC) that often exhibits neuroendocrine phenotypes, suggesting lineage plasticity is involved in CRPC progression. Emergence of cancer stem cells (CSCs) is highly correlated with the lethal phenotypes; the involvement of PCSCs could explain the resistance of CRPC to chemotherapy or radiotherapy. Therefore, elucidating the mechanisms underlying the acquisition of lineage plasticity in prostate cancer (PCSC) is critical for establish the therapeutic strategy targeting the variant types of CRPC. Based on RNA-seq data from a panel of PCa cells with neuroendocrine phenotypes, interferon (IFN) pathway, such as signal transducer and activator of transcription 1 (STAT1), is highly elevated. Clinical observations have found significantly elevated serum IFN levels in PCa patients after ADT and/or irradiation. Meanwhile, IFN-related DNA damage resistance signature (IRDS) encompassed a subset of STAT1-driven genes with pro-survival functions are known to responsible for intrinsic resistance to chemotherapy and radiotherapy in many malignancies. Altogether, we determined to investigate the involvement of STAT1 signaling in the lineage plasticity of CRPC. We applied tumor sphere assay to study the self-renewal capacity of PCSCs in vitro and subcutaneous injection model to examine tumor incidence and tumor growth in vivo. We observed that IRDS and STAT1-driven genes are significantly upregulated in metastatic tumor specimens of PCa patients and CRPC lines acquired lineage plasticity. Inhibition of JAK-STAT1 by specific small molecule inhibitors such as Ruxolitinib or Fludarabine significantly suppresses the self-renewal capacity of CSC spheres in vitro, and attenuates tumor growth in vivo. In particular, we demonstrated that IFIT5, a bona fide IFN inducible gene, appears to be the key molecule in facilitating the acquisition of stemness properties in PCSCs via regulating Bmi1, Sox2 and Nanog through targeting the turnover of miR-128 and miR-101. In addition, loss of IFIT5 attenuates sphere forming ability in vitro, and decreases tumor incidence in vivo. Moreover, IFIT5, STAT1 and several IRDS genes are highly expressed in CRPC lines with neuroendocrine features when compared to adenocarcinoma lines, suggesting association of STAT1 activation with the lineage plasticity of CRPC. Overall, we demonstrated the impact of STAT1 signaling-induced IFIT5-mediated microRNA turnover on the acquisition of stemness properties of PCSCs. The outcome of this study may provide a novel therapeutic strategy for managing the therapy-resistant CRPC.

Citation Format: U-Ging Lo, Yu-An Chen, Ping Mu, Ho Lin, Chih-Ho Lai, Jer-Tsong Hsieh. Interferon induces lineage plasticity of castration-resistant prostate cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6028.

Abstract NG06: CHD1-loss confers AR targeted therapy resistance via promoting cancer heterogeneity and lineage plasticity

BACKGROUND: Pharmacological targeting of driver alterations in cancer has resulted in many clinical successes but is limited by concurrent or novel genomic alterations. One potential explanation for this heterogeneity is the presence of additional genomic alterations which modify the degree of dependence on the targeted driver mutation. Metastatic prostate cancer (mPCa) serves as a relevant example, where the molecular target is the androgen receptor (AR) which functions as a lineage survival factor of luminal prostate epithelial cells. Next generation AR targeted therapies such as abiraterone, enzalutamide and apalutamide have significantly improved the survival of men with mPCa and achieved exciting clinical success. However, resistance to these therapies with disease progression is unfortunately inevitable, with intrinsic resistance noted in around 30% patients and acquired resistance in most patients. Therefore, there is an unmet need to understand the mechanism of therapy resistance to AR targeted therapies and identify novel therapeutic approach to prevent or reverse resistance. Previously, we have revealed that the deactivation of two genes, TP53 and RB1, confers AR targeted therapy resistance through a novel mechanism by which tumor cells acquire lineage plasticity and transit to a multi-lineage, progenitor-like state no longer dependent on AR. This lineage plasticity and resistance is enabled by the activation of SOX2 and is completely reversible by knocking down SOX2. This observation not only adds clarity to the mechanism of resistance, but also suggests that appropriate clinical interventions of lineage plasticity may be a potential avenue to overcome resistance. However, there is only 10% mPCa patients carrying homozygous deletions in both TP53 and RB1 loci, thus additional genomic alterations may be responsible for the resistance in other patients.

METHODS: To gain functional insight into the genes impacted by the copy number alterations in mPCa, we screened 4234 short hairpin RNAs (shRNAs) targeting 730 genes often deleted in human prostate cancer (annotated from a survey of six prostate cancer genomic datasets) for hairpins that confer in vivo resistance to the antiandrogen enzalutamide, in a well credentialed enzalutamide-sensitive xenograft model LNCaP/AR. More than 350 resistant tumors emerged by 16 weeks of xenografting and the genomic DNA of these tumors were extracted and sequenced to determine the enrichment of specific shRNAs compared to the starting material. A classic probabilistic model RIGER-E was used to determine the significance of enrichment of each hairpins/genes.

RESULTS: The chromodomain helicase DNA-binding protein 1 (CHD1) emerged as a top candidate, a finding supported by patient data showing that CHD1 expression is inversely correlated with clinical benefit from AR targeted therapy enzalutamide. CRISPR based depletion of CHD1 confers significant resistance to enzalutamide both in vitro and in vivo, supported by similar results from multiple human prostate cancer cell line models. To our surprise, we observed sustained inhibition of the canonical AR target genes, indicating that CHD1 loss might activate transcriptional programs that relieve prostate tumor cells from their dependence on AR by reprogramming away from their luminal lineage, as we have observed in the setting of combined loss of RB1 and TP53. Indeed, CHD1 loss led to global changes in open and closed chromatin, indicative of an altered chromatin state, with associated changes in gene expression. Integrative analysis of ATAC-seq and RNA-seq changes identified 22 transcription factors as candidate drivers of enzalutamide resistance. CRISPR deletion of four of these (NR3C1, BRN2, NR2F1, TBX2) restored in vitro enzalutamide sensitivity in CHD1 deleted cells. Independently derived, enzalutamide-resistant, CHD1-deleted subclones expressed elevated levels of 1 or more of these 4 transcription factors. This pattern suggests a state of chromatin plasticity and enhanced heterogeneity, initiated by CHD1 loss, which enables upregulation of distinct sets of genes in response to selective pressure. This concept is further supported by RNA-seq data from a mCRPC patients cohort, in which we examined the co-association of CHD1 levels with each of these four TFs across 212 tumors. Unsupervised clustering analysis of just these five genes identified five distinct clusters, four of which display relatively higher expression of either CHD1 or one or two of these four resistance TFs. Interestingly, we observed altered expression of many canonical lineage specific genes in the same panel of CHD1-deleted, enzalutamide resistant xenografts that displayed heterogenous upregulation of the four TFs, including consistent downregulation of luminal genes and upregulation of genes specify epithelial to mesenchymal transition (EMT). Furthermore, these upregulation of 4 resistance TFs, as well as the observed lineage switchs, are both rapid and reversible, suggesting a status of plasticity. Collectively, these results indicate that CHD1 loss establishes an altered chromatin landscape which, in the face of stresses such as antiandrogen therapy, enables resistant subclones to emerge through activation of alternative, non-luminal lineage programs that reduce dependence on AR.

CONCLUSIONS: We demonstrated that loss of the chromodomain gene CHD1, a commonly deleted prostate cancer gene (in 15~20% patients), through global effects on chromatin, establishes a state of plasticity that accelerates the development of AR targeted therapy resistance through heterogeneous activation of downstream effectors, which mediated the transition away from luminal lineage identity and AR dependency. This model provides the first demonstration that early genomic lesions of critical epigenetic modulator promotes prostate cancer heterogeneity and lineage plasticity, consequently leading to the resistance to AR targeted therapy. Therefore, appropriate clinical intervention of these heterogenous resistance driver TFs, as well as the chromatin dysregulation, may be potential therapeutic avenues to prevent or reverse AR targeted resistance.

Citation Format: Zeda Zhang, Chuanli Zhou, Xiaoling Li, Spencer Barnes, Su Deng, Elizabeth Hoover, Chi-Chao Chen, Young Sun Lee, Choushi Wang, Carla Tirado, Lauren Metang, Nickolas Johnson, John Wongvipat, Kristina Navrazhina, Zhen Cao, Wassim Abida, Amaia Lujambio, Sheng Li, Vankat Malladi, Charles Sawyers, Ping Mu. CHD1-loss confers AR targeted therapy resistance via promoting cancer heterogeneity and lineage plasticity [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr NG06.

Proteome and lysine acetylome analysis reveals insights into the molecular mechanism of seed germination in wheat

Seed germination is the first stage in wheat growth and development, directly affecting grain yield and quality. As an important post-translation modification, lysine acetylation participates in diverse biological functions. However, little is known regarding the quantitative acetylproteome characterization during wheat seed germination. In this study, we generated the first comparative proteomes and lysine acetylomes during wheat seed germination. In total, 5,639 proteins and 1,301 acetylated sites on 722 proteins were identified at 0, 12 and 24 h after imbibitions. Several particularly preferred amino acids were found near acetylation sites, including K^acS, K^acT, K^acK, K^acR, K^acH, K^acF, K^acN, K^ac*E, FK^ac and K^ac*D, in the embryos during seed germination. Among them, K^acH, K^acF, FK^ac and K^acK were conserved in wheat. Biosynthetic process, transcriptional regulation, ribosome and proteasome pathway related proteins were significantly enriched in both differentially expressed proteins and differentially acetylated proteins through Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analysis. We also revealed that histone acetylation was differentially involved in epigenetic regulation during seed germination. Meanwhile, abscisic acid and stress related proteins were found with acetylation changes. In addition, we focused on 8 enzymes involved in carbohydrate metabolism, and found they were differentially acetylated during seed germination. Finally, a putative metabolic pathway was proposed to dissect the roles of protein acetylation during wheat seed germination. These results not only demonstrate that lysine acetylation may play key roles in seed germination of wheat but also reveal insights into the molecular mechanism of seed germination in this crop.

Tumor Microenvironment-Derived NRG1 Promotes Antiandrogen Resistance in Prostate Cancer

Despite the development of second-generation antiandrogens, acquired resistance to hormone therapy remains a major challenge in treating advanced prostate cancer. We find that cancer-associated fibroblasts (CAFs) can promote antiandrogen resistance in mouse models and in prostate organoid cultures. We identify neuregulin 1 (NRG1) in CAF supernatant, which promotes resistance in tumor cells through activation of HER3. Pharmacological blockade of the NRG1/HER3 axis using clinical-grade blocking antibodies re-sensitizes tumors to hormone deprivation in vitro and in vivo. Furthermore, patients with castration-resistant prostate cancer with increased tumor NRG1 activity have an inferior response to second-generation antiandrogen therapy. This work reveals a paracrine mechanism of antiandrogen resistance in prostate cancer amenable to clinical testing using available targeted therapies.

Loss of CHD1 Promotes Heterogeneous Mechanisms of Resistance to AR-Targeted Therapy via Chromatin Dysregulation

Metastatic prostate cancer is characterized by recurrent genomic copy number alterations that are presumed to contribute to resistance to hormone therapy. We identified CHD1 loss as a cause of antiandrogen resistance in an in vivo small hairpin RNA (shRNA) screen of 730 genes deleted in prostate cancer. ATAC-seq and RNA-seq analyses showed that CHD1 loss resulted in global changes in open and closed chromatin with associated transcriptomic changes. Integrative analysis of this data, together with CRISPR-based functional screening, identified four transcription factors (NR3C1, POU3F2, NR2F1, and TBX2) that contribute to antiandrogen resistance, with associated activation of non-luminal lineage programs. Thus, CHD1 loss results in chromatin dysregulation, thereby establishing a state of transcriptional plasticity that enables the emergence of antiandrogen resistance through heterogeneous mechanisms.

Downregulation of TMOD1 promotes cell motility and cell proliferation in cervical cancer cells

Tropomodulin-1 (TMOD1) is a key regulator of actin dynamics, which caps the pointed end of actin filaments. TMOD1 has been reported to be involved in several cellular processes, including neurite outgrowth, spine formation and cell migration. Increasing evidence demonstrates that TMOD1 is implicated in several aspects of cancer development. The present study aimed to investigate the role of TMOD1 in cervical cancer. HeLa and CaSki cell lines, derived from human cervical cancer, were used to evaluate the function of TMOD1. Cell motility was measured via a wound-healing assay, with the TMOD1 short hairpin (sh)RNAs transfected cells. Subsequently, cell proliferation was assessed using low serum cell culture condition, while cell cycle distribution was analyzed via flow cytometry. The results demonstrated that downregulated TMOD1 promoted cell motility and proliferation, which is attributed to promotion of G₁/S phase transition in HeLa and CaSki cells. Furthermore, it was indicated that co-expression of shRNA resistant TMOD1 rescued these phenomena. The clinical data demonstrated that high TMOD1 expression is associated with good pathological status in patients with cervical cancer. Overall, the results of the present study indicated that TMOD1 may act as a tumor suppressor in cervical cancer, whereby its downregulated expression was demonstrated to have direct effects on cell motility and cell proliferation. These results provide new evidence for the prognostic prediction of cervical cancer, which may serve as a promising therapeutic strategy for patients with cervical cancer.

Visible and near-infrared driven Yb3+/Tm3+ co-doped InVO4 nanosheets for highly efficient photocatalytic applications

To effectively enhance the utilization of clean sunlight energy, harvesting a large percentage of near infrared (NIR) light is significant. One of the commonly used effective methods for modifying semiconductors is by co-doping upconversion materials on semiconductors to heighten the photocatalytic efficiency. In this work, Yb3+/Tm3+ co-doped InVO4 nanosheets were synthesized by a facile hydrothermal path, and the crystal phases, morphologies, surface chemical compositions, as well as optical properties were characterized. Yb3+/Tm3+ co-doped InVO4 revealed significantly enhanced photoactivity towards chromium(vi) reduction and methyl orange oxidation under visible or NIR light irradiation. Furthermore, 5YT-IV presented the highest electrocatalytic performance and photocatalytic production of H2O2 under visible light irradiation, requiring low overpotential and low Tafel slope (390 mV dec-1) for hydrogen evolution reaction than that of the bare InVO4 (731 mV dec-1), and as well improved the yield of photocatalytic H2O2 production by about 3.5 times. This was primarily ascribed to intensive light absorption resulting from the benign upconversion energy transfer of Yb3+/Tm3+ and the boosted charge separation caused by the intermediate energy states. Moreover, the presence of h+ and ˙O2- as the main oxidative species played a significant role during the photocatalytic oxidation process of methyl orange and electrons played a decisive role in Cr(vi) reduction. This study provides a promising platform for efficiently utilizing the visible-NIR energy of sunlight in the field of photocatalytic H2O2 production and for alleviating environmental pollution in future.

The paracrine induction of prostate cancer progression by caveolin-1

A subpopulation of cancer stem cells (CSCs) plays a critical role of cancer progression, recurrence, and therapeutic resistance. Many studies have indicated that castration-resistant prostate cancer (CRPC) is associated with stem cell phenotypes, which could further promote neuroendocrine transdifferentiation. Although only a small subset of genetically pre-programmed cells in each organ has stem cell capability, CSCs appear to be inducible among a heterogeneous cancer cell population. However, the inductive mechanism(s) leading to the emergence of these CSCs are not fully understood in CRPC. Tumor cells actively produce, release, and utilize exosomes to promote cancer development and metastasis, cancer immune evasion as well as chemotherapeutic resistance; the impact of tumor-derived exosomes (TDE) and its cargo on prostate cancer (PCa) development is still unclear. In this study, we demonstrate that the presence of Cav-1 in TDE acts as a potent driver to induce CSC phenotypes and epithelial–mesenchymal transition in PCa undergoing neuroendocrine differentiation through NFκB signaling pathway. Furthermore, Cav-1 in mCRPC-derived exosomes is capable of inducing radio- and chemo-resistance in recipient cells. Collectively, these data support Cav-1 as a critical driver for mCRPC progression.

Abstract 111: Tumor microenvironment derived NRG1 promotes antiandrogen resistance in prostate cancer

Despite the improved clinical outcomes for patients with advanced prostate cancer due to the use of second generation antiandrogens, acquired drug resistance inevitably occurs and remains the major challenge for prostate cancer therapy. While several cell-autonomous mechanisms of drug resistance have been elucidated previously, for a large number of patients the mechanism of resistance remains unclear. Recent studies point to the importance of the tumor microenvironment (TME), and cancer associated fibroblasts (CAF) in the TME, in mediating tumor progression and resistance to therapy, but whether CAFs specifically contribute to antiandrogen resistance in prostate cancer is not known. Using a preclinical model that faithfully mimics the typical progression of patients on antiandrogen therapy, we found that antiandrogen resistance develops significantly faster when cells are grown in the presence of their cognate CAFs. By carrying out biochemical purification and mass spectrometry analysis, we identified NRG1 as a CAF secreted factor, and found that it can promote antiandrogen resistance in tumor cells, via activation of HER3 in the tumor. Importantly, blocking either NRG1 or HER3 can re-sensitize tumors to antiandrogen treatment in this model. Moreover, NRG1 expression is up-regulated in CAFs after antiandrogen exposure or in androgen deprivation condition. Clinically, increased stroma-NRG1 expression was observed in patients post androgen deprivation therapy but not in hormonally intact men. Taken together, this work has revealed a novel, NRG1-mediated non-cell autonomous mechanism of antiandrogen resistance in prostate cancer, and suggests that therapeutically targeting NRG1 in the setting of metastatic, antiandrogen-resistant prostate cancer with elevated NRG1 could provide significant benefit to patients.

Note: This abstract was not presented at the meeting.

Citation Format: Zeda Zhang, Wouter Karthaus, Jose Mauricio Mota, Ping Mu, Chao Wu, Wassim Abida, Eliot Linton, Young Sun Lee, Eugine Lee, Ninghui Mao, Elizabeth Adams, Danielle Choi, Dana E. Rathkopf, Brett Carver, Anuradha Gopalan, Xuejun Jiang, Philip Watson, Charles Sawyers. Tumor microenvironment derived NRG1 promotes antiandrogen resistance in prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 111.

Cholinergic system in sleep regulation of emotion and motivation

Sleep profoundly regulates our emotional and motivational state of mind. Human brain imaging and animal model studies are providing initial insights on the underlying neural mechanisms. Here, we focus on the brain cholinergic system, including cholinergic neurons in the basal forebrain, ventral striatum, habenula, and brain stem. Although much is learned about cholinergic regulations of emotion and motivation, less is known on their interactions with sleep. Specifically, we present an anatomical framework that highlights cholinergic signaling in the integrated reward-arousal/sleep circuitry, and identify the knowledge gaps on the potential roles of cholinergic system in sleep-mediated regulation of emotion and motivation. Sleep impacts every aspect of brain functions. It not only restores cognitive control, but also retunes emotional and motivational regulation [1]. Sleep disturbance is a comorbidity and sometimes a predicting factor for various psychiatric diseases including major depressive disorder, anxiety, post-traumatic stress disorder, and drug addiction [2-9]. Although it is well recognized that sleep prominently shapes emotional and motivational regulation, the underlying neural mechanisms remain elusive. The brain cholinergic system is essential for a diverse variety of functions including cognition, learning and memory, sensory and motor processing, sleep and arousal, reward processing, and emotion regulation [10-14]. Although cholinergic functions in cognition, learning and memory, motor control, and sleep and arousal have been well established, its interaction with sleep in regulating emotion and motivation has not been extensively studied. Here we review current evidence on sleep-mediated regulation of emotion and motivation, and reveal knowledge gaps on potential contributions from the cholinergic system.

High-Throughput Screening of Rat Mesenchymal Stem Cell Behavior on Gradient TiO2 Nanotubes

The dimension of TiO₂ nanotubes (TNTs) ranges from several nanometers to hundreds of nanometers. This variety raises the difficulty of screening suitable nanotube dimension for biomedical applications. Herein, we report the use of a simple one-step bipolar anodization method for fabrication of TNT gradients with diameter range from 30 to 100 nm. The gradient TNTs were successfully applied for high-throughput screening of TNT size effect on cell responses, including cell adhesion, proliferation, and differentiation. Results reveal that no significant difference in adherent cell number could be found within the range of 30-87 nm in both the presence and absence of serum proteins. On the contrary, large nanotubes (with outer diameter >87 nm) profoundly reduce cell adhesion in both the presence and absence of serum proteins, indicating TNT size could affect cell adhesion directly without the adsorbed proteins. The size effect on cell behavior becomes prominent with time that cell proliferation and differentiation decrease with increasing nanotube size. This size effect can be comprehended by protein adsorption and the formation of focal adhesion. Another two sample applications of gradient TNTs demonstrate gradient TNTs are promising for high-throughput screening.

Expression, regulation and function of MicroRNAs in endometriosis

Endometriosis (EMS), characterized by the presence and growth of functional en do met rial-like tissues outside the uterine cavity, is a common and benign gyneco logical disorder with a poorly understood and somewhat enigmatic etiopathogenesis and pathophysiology. MicroRNAs (miRNAs) are single-stranded 19-25 nucleotide-long RNAs and have an important role in post-transcriptional gene silencing by base pairing with target mRNAs. Recent research has shown that miRNAs and their target mRNAs are differentially expressed in endometriosis and other disorders of the female reproductive system. In this paper, we review the recent progress in understanding the roles of miRNAs in endometriosis, and specific miRNAs as biomarkers and therapeutic targets for endometriosis.

NEMO-IKKβ Are Essential for IRF3 and NF-κB Activation in the cGAS-STING Pathway

Cytosolic dsDNA activates the cyclic GMP-AMP synthase (cGAS)-stimulator of IFN genes (STING) pathway to produce cytokines, including type I IFNs. The roles of many critical proteins, including NEMO, IKKβ, and TBK1, in this pathway are unclear because of the lack of an appropriate system to study. In this article, we report that lower FBS concentrations in culture medium conferred high sensitivities to dsDNA in otherwise unresponsive cells, whereas higher FBS levels abrogated this sensitivity. Based on this finding, we demonstrated genetically that NEMO was critically involved in the cGAS-STING pathway. Cytosolic DNA activated TRIM32 and TRIM56 to synthesize ubiquitin chains that bound NEMO and subsequently activated IKKβ. Activated IKKβ, but not IKKα, was required for TBK1 and NF-κB activation. In contrast, TBK1 was reciprocally required for NF-κB activation, probably by directly phosphorylating IKKβ. Thus, our findings identified a unique innate immune activation cascade in which TBK1-IKKβ formed a positive feedback loop to assure robust cytokine production during cGAS-STING activation.

Rb1 and Trp53 cooperate to suppress prostate cancer lineage plasticity, metastasis, and antiandrogen resistance

Prostate cancer relapsing from antiandrogen therapies can exhibit variant histology with altered lineage marker expression, suggesting that lineage plasticity facilitates therapeutic resistance. The mechanisms underlying prostate cancer lineage plasticity are incompletely understood. Studying mouse models, we demonstrate that Rb1 loss facilitates lineage plasticity and metastasis of prostate adenocarcinoma initiated by Pten mutation. Additional loss of Trp53 causes resistance to antiandrogen therapy. Gene expression profiling indicates that mouse tumors resemble human prostate cancer neuroendocrine variants; both mouse and human tumors exhibit increased expression of epigenetic reprogramming factors such as Ezh2 and Sox2. Clinically relevant Ezh2 inhibitors restore androgen receptor expression and sensitivity to antiandrogen therapy. These findings uncover genetic mutations that enable prostate cancer progression; identify mouse models for studying prostate cancer lineage plasticity; and suggest an epigenetic approach for extending clinical responses to antiandrogen therapy.

SOX2 promotes lineage plasticity and antiandrogen resistance in TP53- and RB1-deficient prostate cancer

Some cancers evade targeted therapies through a mechanism known as lineage plasticity, whereby tumor cells acquire phenotypic characteristics of a cell lineage whose survival no longer depends on the drug target. We use in vitro and in vivo human prostate cancer models to show that these tumors can develop resistance to the antiandrogen drug enzalutamide by a phenotypic shift from androgen receptor (AR)-dependent luminal epithelial cells to AR-independent basal-like cells. This lineage plasticity is enabled by the loss of TP53 and RB1 function, is mediated by increased expression of the reprogramming transcription factor SOX2, and can be reversed by restoring TP53 and RB1 function or by inhibiting SOX2 expression. Thus, mutations in tumor suppressor genes can create a state of increased cellular plasticity that, when challenged with antiandrogen therapy, promotes resistance through lineage switching.

Abstract 4165: SOX2 promotes lineage plasticity and antiandrogen resistance in TP53 and RB1 deficient prostate cancer

Some cancers evade targeted therapies through a mechanism known as lineage plasticity, whereby tumor cells acquire phenotypic characteristics of a cell lineage whose survival no longer depends on the drug target. Here we show, using in vitro and in vivo prostate cancer models, that these tumors can develop resistance to the antiandrogen drug enzalutamide by a phenotypic shift from androgen receptor (AR) dependent luminal epithelial cells to AR independent basal-like cells. This lineage plasticity is enabled by loss of TP53 and RB1 function, is mediated by increased expression of the reprogramming transcription factor SOX2 and can be reversed by restoring TP53 and RB1 function or by inhibiting SOX2 expression. Thus, mutations in tumor suppressor genes can create a state of increased cellular plasticity that, when challenged with antiandrogen therapy, promotes resistance through lineage switching.

Citation Format: Ping Mu, Zeda Zhang, Matteo Benelli, Wouter Karthaus, Elizebeth Hoover, Chi-Chao Chen, John Wongvipat, Sheng-Yu Ku, Dong Gao, Zhen Cao, Neel Shah, Elizabeth Adams, Wassim Abida, Philip Watson, Davide Prandi, Chun-Hao Huang, Elisa de Stanchina, Scott Lowe, Leigh Ellis, Himisha Beltran, Mark Rubin, David Goodrich, Francesca Demichelis, Charles L. Sawyers. SOX2 promotes lineage plasticity and antiandrogen resistance in TP53 and RB1 deficient prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4165. doi:10.1158/1538-7445.AM2017-4165

Abstract 2170: Rb1 suppresses prostate cancer metastasis and lineage plasticity underlying castration resistance

Androgen deprivation therapy (ADT) is an effective treatment for metastatic prostate cancer (mPCa), but patients eventually relapse with ADT resistant disease. Well-characterized mechanisms of ADT resistance include AR amplification, intra-tumoral androgen synthesis, AR splice variants, and growth receptor bypass. All of these mechanisms function to maintain sufficient AR signaling for tumor growth and survival. Improved ADT like abiraterone acetate (AA) and enzalutamide (Enza) were developed to combat such resistance mechanisms associated with alterations in androgen receptor or androgen metabolism. While AA and Enza extend survival, clinical benefits are short-lived. A new form of resistance is increasingly appreciated in patients relapsing from AA or Enza, histologic transformation of prostate adenocarcinoma (PADC) to neuroendocrine prostate cancer (NEPC) variants. NEPC is lethal and the survival time is less than a year as effective targeted therapy is unavailable. NEPC typically exhibits reduced AR expression, increased expression of neuroendocrine markers, and visceral metastasis in the absence of rising PSA. Of note, NEPC possesses the similar genome rearrangements with adjacent PADC cells, indicating they share clonal origin. Thus, NEPC may arise by histologic transformation of PADC. Underlying mechanisms of histologic transformation are not understood and experimental models are limited, hindering development of effective remedies. RB1 loss is common in NEPC, but rare in PADC; genetic profiling shows human NEPC exhibit elevated levels of several epigenetic modifiers. We hypothesize that transdifferentiation from PADC to NEPC in the context of RB1 loss is due to epigenetic alterations and can be reversed or blocked by epigenetic targeted therapies. We established several genetically engineered mouse models (GEMMs) to test the role of Rb1, and we find Rb1 loss causes metastatic progression of PADC initiated by Pten deficiency. This Rb1/Pten deficient (DKO) PADC exhibits expression markers for both PADC and NEPC as seen in human patients. Yet, these tumors are sensitive to ADT but relapse with low AR expression and acquired Trp53 mutations. RNA profiling demonstrates the phenotype of DKO tumors is similar to human NEPC. Both human and mouse NEPC is accompanied by increased expression of epigenetic reprogramming factors like Sox2 and Ezh2. Clinically relevant Ezh2 inhibitors GSK126 and EPZ6438 can restore Enza sensitivity by reversing neuroendocrine transformation. This finding has been genetically validated using short-hairpin RNA(shRNA) in vitro. These results uncover genetic mutations driving prostate cancer lineage plasticity and suggest an epigenetic approach for extending the clinical benefits of ADT.

Citation Format: Sheng-Yu Ku, Spencer Rosario, Yanqing Wang, Ping Mu, Mukund Seshadri, Zachary Goodrich, Maxwell Goodrich, David P. Labbé, Eduardo Cortez Gomez, Jianmin Wang, Henry W. Long, Bo Xu, Myles Brown, Massimo Loda, Charles L. Sawyers, Leigh Ellis, David G. Goodrich. Rb1 suppresses prostate cancer metastasis and lineage plasticity underlying castration resistance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2170. doi:10.1158/1538-7445.AM2017-2170

[Effect on time of temporarily-closed wound drainage on blood loss of primary total knee arthroplasty after intravenous and intra-articular injection of tranexamic acid]

Objective

To investigate the effect and safety of time of temporarily-closed wound drainage on blood loss of primary total knee arthroplasty (TKA) after intravenous and intra-articular injection of tranexamic acid (TXA).

Methods

Eighty female patients were selected from 102 patients who underwent primary TKA between September 2015 and July 2016, who were randomly divided into 4 groups: control group (group A), 30 minutes group (group B), 60 minutes group (group C), and 90 minutes group (group D), 20 patients each group. No significant difference was found in age, body mass index, side, pathogen, duration, and preoperative hemoglobin, albumin, and hematocrit between 4 groups ( P>0.05). All the patients received intravenous injection of 1 g TXA at 10 minutes before removing the tourniquet. The patients in group A were injected with 60 mL normal saline into the articular cavity and closed drainage after surgery, while the patients in groups B, C, and D were injected with 60 mL TXA into the articular cavity and closed drainage for 30, 60, and 90 minutes respectively. The volume of drainage at 24 hours after operation, the total blood loss, the postoperative hemoglobin level, maximum hemoglobin loss, albumin loss, the volume and frequency of blood transfusion, venous thrombo embolism rate, and pulmonary embolism rate were recorded and compared between groups.

Results

The volume of drainage and total blood loss in groups B, C, and D were less than those of group A, showing significant difference between groups C, D and group A ( P<0.05), but no significant difference between group B and group A ( P>0.05). The volume of drainage at 24 hours after operation in group B was higher than that in groups C and D, showing significant difference between groups B and D ( P<0.05), but no significant difference was found between groups C and D ( P>0.05). There was no significant difference in the total blood loss between groups B, C, and D ( P>0.05). The hemoglobin loss and albumin loss gradually decreased from groups A to D, but no significant difference was found between groups ( P>0.05). No venous thrombo embolism and pulmonary embolism occurred. The hemoglobin value decreased to 28 g/L at 3 days after operation in 1 patient of group D, who received venous transfusion of 20 g human albumin.

Conclusion

Intravenous and topical application of TXA in TKA can significantly decrease postoperative bleeding. Topical TXA combined with 60 minutes temporarily-closed wound drainage may reduce postoperative blood loss to the greatest extent without increasing the risk of venous thrombo and pulmonary embolism event after TKA．.

Downregulation of CREB Promotes Cell Proliferation by Mediating G1/S Phase Transition in Hodgkin Lymphoma

The cyclic-AMP response element-binding protein (CREB), a well-known nuclear transcription factor, has been shown to play an essential role in many cellular processes, including differentiation, cell survival, and cell proliferation, by regulating the expression of downstream genes. Recently, increased expression of CREB was frequently found in various tumors, indicating that CREB is implicated in the process of tumorigenesis. However, the effects of CREB on Hodgkin lymphoma (HL) remain unknown. To clarify the role of CREB in HL, we performed knockdown experiments in HL. We found that downregulation of CREB by short hairpin RNA (shRNA) resulted in enhancement of cell proliferation and promotion of G₁/S phase transition, and these effects can be rescued by expression of shRNA-resistant CREB. Meanwhile, the expression level of cell cycle-related proteins, such as cyclin D1, cyclin E1, cyclin-dependent kinase 2 (CDK2), and CDK4, was elevated in response to depletion of CREB. Furthermore, we performed chromatin immunoprecipitation (ChIP) assay and confirmed that CREB directly bound to the promoter regions of these genes, which consequently contributed to the regulation of cell cycle. Consistent with our results, a clinical database showed that high expression of CREB correlates with favorable prognosis in B-cell lymphoma patients, which is totally different from the function of CREB in other cancers such as colorectal cancer, acute myeloid leukemia, and some endocrine cancers. Taken together, all of these features of CREB in HL strongly support its role as a tumor suppressor gene that can decelerate cell proliferation by inhibiting the expression of several cell cycle-related genes. Our results provide new evidence for prognosis prediction of HL and a promising therapeutic strategy for HL patients.