第9卷，第1期

Eukaryotic chromosomes occupy specific territories in the nucleus, which is key for genome stability and function. Based on the spatiotemporal organization and compaction pattern, eukaryotic chromatins can be recognized as transcriptionally active and loosely packed euchromatin in the nuclear interior and transcriptionally repressive and highly compacted heterochromatin at the nuclear periphery or around nucleoli. Mounting evidence suggests that heterochromatin plays a critical role in maintaining genome stability and function by preserving the chromosome integrity and repressing or limiting transcription of repetitive DNA. Heterochromatin can be generally subcategorized into constitutive and facultative types. Constitutive heterochromatin is usually found at repetitive satellite DNA regions such as those at peri-centromeres and telomeres. On the other hand, facultative heterochromatin is rich in repetitive transposons and can lose its condensed structure and become transcriptionally active under specific developmental or environmental conditions. A hallmark of constitutive heterochromatin is tri-methylation at the 9th lysine residue of the histone protein H3 (commonly known as H3K9me3), which is carried out by the 'writer', suppressor of variegation 3-9 homolog 1/2 (SUV39H1/2), and will be recognized by the ' reader', heterochromatin protein 1 (HP1). Human HP1 has three paralogues, HP1a, b and g, which are encoded by three different genes, chromobox homolog 5 (Cbx5), Cbx1, and Cbx3, respectively. It seems that HP1α is commonly associated with constitutive heterochromatin, whereas HP1b and HP1g have both genesilencing and gene-activating roles, probably due to the slight structural difference.

1213

Human microbiome studies have exploded in number in recent years with the advent of high-throughput sequencing methods. The dramatic increase in sensitivity facilitated by deep-sequencing capability has led to hundreds of studies characterizing microbial communities in multiple human tissues, as well as the relationships between the composition of these communities and disease. The most-studied body sites in this regard have been the components of the gastrointestinal (GI) tract, partially driven by stool sample sequencing. Stool can be utilized as a non-invasive way to query the human gut. Gut microbiome studies have revealed important connections with many diseases, including cancer. More recent works have begun to investigate microflora at cancer sites themselves in a variety of solid tumor types, finding microbial "signatures" that can distinguish tumors from normal tissues of the same type. These signatures are also distinct between tumor types and are detectable, to some degree, in circulation, raising the possibility of a blood-based test for cancer based on microbial DNA.

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Although extensively studied, it is unknown what is the major cellular energy driving tumor metastasis after anti-cancer radiotherapy. Metabolic reprogramming is one of the fundamental hallmarks in carcinogenesis and tumor progression featured with the increased glycolysis in solid tumors. However, accumulating evidence indicates that in addition to the rudimentary glycolytic pathway, tumor cells are capable of reactivating mitochondrial OXPHOS under genotoxic stress condition to meet the increasing cellular fuel demand for repairing and surviving anti-cancer radiation. Such dynamic metabolic rewiring may play a key role in cancer therapy resistance and metastasis. Interestingly, data from our group and others have demonstrated that cancer cells can re-activate mitochondrial oxidative respiration to boost an annexing energy to meet the increasing cellular fuel demand for tumor cells surviving genotoxic anti-cancer therapy with metastatic potential.

1466

Ovarian cancer (OC) is the most lethal type of cancer among female genital tumors. Along with debulking surgeries, platinum is the first-line chemotherapy treatment, whereas chemoresistance is the biggest obstacles in a poor prognosis of OC. Identifying a novel therapeutic target for OC chemoresistance remains an urgent need. lncRNAs are expressed in tissue-specific patterns and distributed in the specific subcellular locations. The diverse regulatory mechanisms of lncRNAs are dependent on their subcellular location. lncRNA CERNA1, which is mainly located in the cytoplasm of HUVECs, acts as a miRNA sponge. Here, for the first time, we described the role and the molecular regulatory mechanism of nuclear CERNA1 in OC. We found that CERNA1 was poorly expressed in both OC tissues and OC cells, which predicts a poor OC prognosis. Unlike in HUVECs, CERNA1 is distributed almost exclusively in the nucleus of OC cells. Nuclear CERNA1 induced BCL2L10 expression (an OC tumor repressor), promoted cell apoptosis and reduced the cisplatin resistance by decoying DNMT1 from the BCL2L10 promoter. These results suggest that CERNA1 might be an attractive therapeutic target for improving the sensitivity to chemotherapy for OC patients.

1263

Due to the use of more adjuvant therapies and the increasing prevalence of associated diseases, nontraumatic osteonecrosis of the femoral head (ONFH) has become a substantial worldwide health issue; while glucocorticoid administration was the highest-ranked risk factor, with a proportion ranging from 26.35 to 55.75%. Albeit with similar radiological features, glucocorticoid-induced ONFH (GONFH) manifested a greater probability for advance-to-late-stage (post-collapse) lesions in comparison with its non-glucocorticoid-induced counterparts. Therefore, an accurate and timely diagnosis of osteonecrosis following glucocorticoid therapy is of great significance to initiate nonoperative treatment regimens or joint-preserving procedures, slow disease progression, and defer or avert joint arthroplasty.

1249

Cholelithiasis-induced cholestasis is one of the most common causes of hospitalization due to gastrointestinal disease, yet considerable know ledge gaps exist in the pathogenesis of this disease. This can partially be explained by inadequate characterization of experimental cholestasis models. Here, we compared the transcriptional profile of commonly used mouse models for obstructive cholestasis and benchmarked them to human disease to identify the model (s) best suited for cholelithiasis-induced cholestasis research and to uncover conserved mechanism s involved in hum an and murine cholestasis. Selected mouse models included bile duct ligation (BDL) surgery and 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) diet, and a drug-induced cholestasis model using cyclosporin A (CsA), in an acute and chronic setting. Human samples were collected from patients with cholelithiasis-induced cholestasis of an acute (HUMAC) and recurrent nature (HUMREC). RNA sequencing was performed on mouse and human liver tissue. Both the BDL and DDC models, but not the CsA model, were shown to be applicable for studying cholelithiasis-induced cholestasis, with transcriptomic profiles that highly correspond to acute cholestasis in hum an patients. In particular, the conservation of canonical pathways related to the inflammatory response and cytoskeleton organization, in which the Rho family GTPase is involved, were identified. Our study furthermore revealed promising mechanistic-based transcriptomic biomarkers relevant for murine and human cholestasis, which could potentially be useful for robust prediction and detection of diverse types of cholestatic liver disease.

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Cardiovascular diseases (CVDs) are responsible for 30% of all deaths globally. Coronary heart disease (CHD), is the most common form of CVD, accounting for 46% of male and 38% female cardiovascular deaths. CHD is characterized by chronic inflammation and endothelial injuries in coronary arteries, and subsequent development of atherosclerotic plaques which eventually leads to myocardial ischemia. CHD is influenced by both genetic and environmental factors, and is prevalent in all parts of the world. Regulatory non-coding RNAs (ncRNAs) e.g., long-chain ncRNAs, circRNAs, and miRNAs, are involved in the regulation of approximately 60% of protein-coding genes. Thus, ncRNAs partake in the regulation of many cellular processes. Dys-regulation of ncRNAs is a major underlying event in the pathogenesis of many diseases. Despite the vast information about CHD, frequency of the disease is still rising. Therefore, a study on the role of ncRNAs in CHD pathology is necessary to expand the understanding of molecular basis of the disease and pave way for its new diagnostic and treatment approaches. We demonstrated that hsa_-circ_0092576 and its target miRNAs are vital in the regulation of genes related to CHD pathology, and thus could be promising biomarkers of the disease.

1214

Irisin, a secreted myokine actively cleaved from fibronectin type III domain-containing protein 5 (FNDC5), plays a crucial role in whole-body metabolism. To date, irisin receptor has not been identified, and its signal transduction is mostly unknown. Irisin is regulated by peroxisome proliferator-activated receptor-gamma (PPARγ) coactivator-1-alpha (PGC1α). We previously showed that PPARγ directly regulates pancreatic lipase (PL), the principal dietary lipolytic enzyme that plays an essential role in dietary fat digestion, linking dietary fat to PL regulation. Pancreatic lipase-related protein 2 (PLRP2) sharing high homology with PL is also produced and secreted by the pancreas, although in different expression patterns and with different substrate specificity. Irisin and PL share specific nutrient regulation (fatty acids) and partial signal transduction pathway, yet the role of irisin in exocrine pancreas function is unknown. We aim to study FNDC5/irisin role in the exocrine pancreas functionality.

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Although diffuse large B-cell lymphoma (DLBCL) is considered as a curable disease after standard immunochemotherapy, approximately 30% of patients would succumb to short survival. To date, clinical presentations and gene expressions have been used to identify these high-risk patients. Recently, genetic alterations are used to model their proposed classifiers. For example, four, five and seven genetic subtypes were respectively found by Schmitz, Chapuy and George colleagues as a method for tailored treatment. However, these classifiers were calculated using the complex tools such as the LymphGen classifier and consensus clustering algorithm. Besides, mutated genes were not enough to estimate their genetic subtypes by their proposed tools, which need additional data such as copy number alteration and chromosome translocations. What's more, there is still not a consistent classifier to validate predefined subtypes. Thus, it is difficult to apply these genetic tools in clinical practice. In order to translate into clinical practice easily, a smaller gene-set using the easyto-implement method will be practical instead of measuring genome-wide sequencing. In this context, we searched for a small number of genes using targeted next-generation sequencing, and established its predictive ability for DLBCL patients.

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The adenosine deaminase acting on RNA (ADAR) protein family was well characterized as RNA editing enzymes converting adenosines to inosines (A-to-I) in dsRNA structures. They share a homologous structure including the dsRNA-binding domain and the deaminase domain. ADAR1 function as the primary editing enzyme for A-to-I mutation because of its higher and ubiquitous expression compared to ADAR2 and ADAR3 in eukaryotes. ADAR1 has recently shown to regulate the canonical RNA sensing pathways such as retinoic acid-inducible gene-I-like receptors (RLRs) and protein kinase R (PKR). And the level of dsRNA recognition and editing by ADAR1 plays an important role in restraining autoimmunity activity and maintaining self-tolerance. Since a large amount of posttranscriptional editing of A-to-I conversions was detected in mammals, the biological effects and the accurate role of ADAR1 in human diseases have attracted increased attention. Previous reports suggest that ADAR1 is involved in more than ten types of tumors. However, the prognostic and therapeutic effects of ADAR1 in cancers have not been fully investigated.

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Tissue inhibitor of metalloproteinases 3 (TIMP3) regulates turnover of the extracellular matrix (ECM) and is also a potent inhibitor of the vascular endothelial growth factor receptor 2 (VEGFR2), a key mediator of angiogenesis. Mutations in TIMP3 give rise to Sorsby's fundus dystrophy (SFD), a dominantly inherited degenerative disease of the retina that leads to blindness, usually in middle age. To date, fifteen different mutations in TIMP3 have been identified as causing the disease. Conventionally, these were numbered for their positions in the secreted protein, excluding the signal sequence but are referenced in Table S1, with and without including the signal sequence; however, we use the conventional nomenclature in the text. illustrates their relationship to the primary structure. Thirteen of these are missense mutations, one a nonsense mutation and one a mutation in the splice acceptor site at the intron 4/exon 5 boundary. All but one of these mutations (S15C) affect exon 5, which codes for all except the first 3 residues of the carboxyl-terminal domain of the molecule. Notably, eleven mutations result in a change to a cysteine residue, while the nonsense mutation (E139X), also gives rise to an unpaired cysteine residue. It seems unlikely that this is coincidental. Indeed, we have shown many of these Cys residues result in dimerization and/or multimerization of the TIMP3 protein. Moreover, the E139K missense mutation and the E139X nonsense mutation have also been shown to form disulfide bonded dimers, strengthening the hypothesis that TIMP-3 dimerization is a prerequisite for the disease. However, the H158R mutation and the S15C mutation have both been reported to be solely monomeric, challenging this hypothesis. Moreover, the molecular consequences of several other mutations, and the novel splice acceptor site mutation have never been examined.

1227

Small-cell lung cancer (SCLC) is a highly malignant cancer with characteristics of rapid growth, abundant angiogenesis, and early distant metastasis that accounts for about 15% of lung cancers. With the wide application of low-dose computed tomography screening in recent years, the incidence of early limited-stage SCLC has increased dramatically. Clinical trials and real-world data have shown that surgical resection followed by adjuvant chemotherapy with or without radiotherapy is the recommended treatment for selected cases of limited-stage SCLC. However, due to chemotherapy resistance, the high frequency of postoperative recurrence reduces the long-term survival of SCLC patients. Therefore, there is an urgent need for more precise classification strategies to identify patients who can benefit from adjuvant chemotherapy.

1268

Androgenic alopecia (AGA) is the most common type of clinical alopecia. Androgen receptor (AR) is the most logical candidate gene for regulating the occurrence of AGA. Dermal papilla cells (DPCs) are a special kind of mesenchymal cells, located in the hair bulb of hair follicles. DPCs play a role in maintaining and inducing the periodic cycling of hair follicles, and are considered as a key cell target of androgen in hair follicles. Tcf4 is a positive regulator of the maintenance of DPC biological features. Previously, we reported that Twist1 can enhance the inductive effect of Tcf4. As a transcription factor, AR can bind with Tcf4 to regulate the proliferation in prostate growth and tumorigenesis. However, whether and how AR interacts with Tcf4 in DPCs remains unknown.

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Congenital heart disease (CHD) is one of the most common causes of neonatal mortality. The worldwide morbidity of CHD is 9.410‰, while the proportion of CHD patients who are reported to carry mutations in coding regions is < 50%. Enhancers play an important role in the spatio-temporal expression of target genes, and a lot of related variations are associated with CHD. There are conserved and nonconserved enhancers. It is common to study conserved enhancers in model organisms, while nonconserved enhancers lack systematic investigation and functional validation. Unfortunately, lots of CHD patients have no diagnosis even after whole exome sequencing (WES) analysis, while the significance of nonconserved regulatory regions, one of the potential pathogenic factors, is usually overlooked. Therefore, inthisstudy, to facilitate studies on the etiology of CHD, we present a systematic genome-wide analysis and functional validations of nonconserved human-specific enhancers (NoHEs).

1292

Obesity is caused by an excessive accumulation of fat, which poses a risk to human health. In China, the prevalence rates of overweight and obesity in adults were estimated to be 30.1% and 11.9%, respectively, ranking the first in the world. Obesity is a major risk factor for hypertension. However, most of the overweight adults maintain normal blood pressure (BP), and only ~43.6% of obese people developed hypertension. The mechanism and key link for promoting obesity to hypertension are still unclear. Genome-wide association studies (GWAS) attempt to discover genetic variations that associate with obesity and hypertension. Although these studies suggest a close relationship between obesity and hypertension, only 10%-20% of the increase in BP can be explained by increased body mass index (BMI). In this study, we observed that several genes were associated with both hypertension and obesity, which gave us an opportunity to find and identify the common genetic background of hypertension and obesity, or obesity-related hypertension.

1847

Myocardial ischemia (MI) is a common disease with high mortality and morbidity worldwide. Since the pathological process of MI is very complicated, a comprehensive understanding of its pathogenesis is the key to the treatment of MI. As chromatin plays a crucial role in regulating gene expression, and gene regulation is a fundamental process in developing and disease progression, combined analysis of the chromatin and gene can further reveal the pathological mechanism of MI. In this study, Assay for Transposase-Accessible Chromatin with high throughput sequencing (ATAC-seq) was used to identified open chromatin, RNA-seq was applied to detected differential expression profiling. The combined analysis of ATAC-seq and RNA-seq showed that inflammatory response was critical in MI injury. Analysis of transcription factors (TFs) found a key TF, STAT2 (signal transducers and activators of transcription 2). The annotation analysis of target genes predicted by Stat2 found most of these genes were involved in inflammation, which indicated Stat2 was a key regulator of inflammatory response after MI. This study reveals a deeper regulatory mechanism of inflammation after MI from the levels of chromatin, TFs, and genes; Stat2 may be the core of this regulator network. These results provide a more specific target for early intervention of inflammation after MI.

1321

Idiopathic hypogonadotropic hypogonadism (IHH) is a rare genetic disease with clinical and genetic heterogeneity. This study aimed to investigate a novel causal gene of IHH and a homozygous mutation (p.Ala515Val) in SEMA4D, and sought to determine the mechanism of SEMA4D promoting GnRH neurons migration. The detailed materials and methods were shown in Supplementary Methods. Combination of bioinformatics, in silico analysis and in vitro analysis indicated the homozygous mutation as a loss-of-function mutation. Functional experiments were conducted to explore SEMA4D modulating GN11 cells migration through SEMA4D/PlexinB1/Met/Rnd1/RhoA/Raf1/MAPK signaling pathway. The results of in vivo experiment demonstrated the reduced population of GnRH neurons at the hypothalamus in Sema4D^-/-mice models with normal serum testosterone level, reproductive system, and quality of sperm, consistent with the oligogenic pathogenicity of IHH. In this study, we expanded the genetic spectrum of IHH, and provided theoretical basis for genetic diagnosis and personalized treatment of IHH patients.

1287

Synthetic lethality describes an interaction whereby the co-occurrence of two mutations leads to cell death but one mutation alone does not, which can be exploited for cancertherapeutics. Due to lacking effective nonsurgical treatment and early clinical diagnosis markers, patients have high mortality and low overall survival rates in cholangiocarcinoma (CCA). Based on our previous predicted results in CCA (SLOAD, http: //tmliang.cn/SL), ARID1A: ALDH2 is a pair gene with synthetic lethal. Thus, the involvement of ARID1A in maintaining genome stability makes it a potential candidate for synthetic lethal therapy of ARID1A-deficient tumors. ALDH2 belongs to aldehyde dehydrogenase (ALDH) family. Endogenous aldehyde accumulation is considered as an important source of cellular reactive oxygen species (ROS). The synthetic lethal interaction between ARID1A and ALDH2 was detected in 11 cancer types. Simultaneously, the synthetic lethal interaction was also screened in another research. Finally, the common ARID1A: ALDH2 gene pair in the two datasets was selected for further experimental validation. We cultured CCA cells (HCCC9810 and HuCCT1) in vitro and constructed the stable cell lines of ARID1A knockout and cooperate with ALDH2 inhibitor (disulfiram, DSF) to explore whether there was synthetic lethality between ARID1A and ALDH2. Cell cloning experiment showed that there were no significant changes on growth rate of CCA cells after ARID1A knockout or treatment with DSF. However, after treatment with DSF, there was markedly inhibition on the survival of CCA cells in the case of ARID1A knockout (P < 0.05).

1213

Obesity related non-alcoholic fatty liver disease (NAFLD), which can progress to steatohepatitis and insulin resistance, has become a major chronic liver disease worldwide. As an adaptor of clathrin-mediated endocytosis, Epsin1 plays a role in many diseases, including tumors, atherosclerosis and diabetic wound healing. Epsins contain a conserved NH₂-terminal homology domain (ENTH), which binds to lipids on plasma membrane. Here, we investigated the role of Epsin1 in the regulation of hepatic lipid and glucose metabolism. Results showed that hepatic Epsin1 overexpression improved insulin tolerance test, and alleviated hepatic steatosis, hyperglycemia and hyperlipidemia in diet-induced obese (DIO) mice. Besides, Epsin1 overexpression reduced the expression of gluconeogenic genes, lipogenic genes, and increased lipolytic genes in the liver. Proteomic data indicated that Epsin1 overexpression reduced the levels of the proteins involved in lipid synthesis and gluconeogenesis.

1239

Molecular target inhibitors have been regularly approved by Food and Drug Administration (FDA) for tumor treatment, and most of them intervene in tumor cell proliferation and metabolism. The RAS-RAF-MEK-ERK pathway is a conserved signaling pathway that plays vital roles in cell proliferation, survival, and differentiation. The aberrant activation of the RAS-RAF-MEK-ERK signaling pathway induces tumors. About 33% of tumors harbor RAS mutations, while 8% of tumors are driven by RAF mutations. Great efforts have been dedicated to targeting the signaling pathway for cancer treatment in the past decades. In this review, we summarized the development of inhibitors targeting the RAS-RAF-MEK-ERK pathway with an emphasis on those used in clinical treatment. Moreover, we discussed the potential combinations of inhibitors that target the RAS-RAF-MEK-ERK signaling pathway and other signaling pathways. The inhibitors targeting the RAS-RAF-MEK-ERK pathway have essentially modified the therapeutic strategy against various cancers and deserve more attention in the current cancer research and treatment.

1330

The last few decades have witnessed an advancement in our understanding of multiple cancer cell pathways related to metabolic reprogramming. One of the most important cancer hallmarks, including aerobic glycolysis (the Warburg effect), the central carbon pathway, and multiple-branch metabolic pathway remodeling, enables tumor growth, progression, and metastasis. Phosphoenolpyruvate carboxykinase 1 (PCK1), a key rate-limiting enzyme in gluconeogenesis, catalyzes the conversion of oxaloacetate to phosphoenolpyruvate. PCK1 expression in gluconeogenic tissues is tightly regulated during fasting. In tumor cells, PCK1 is regulated in a cell-autonomous manner rather than by hormones or nutrients in the extracellular environment. Interestingly, PCK1 has an anti-oncogenic role in gluconeogenic organs (the liver and kidneys), but a tumor-promoting role in cancers arising from non-gluconeogenic organs. Recent studies have revealed that PCK1 has metabolic and non-metabolic roles in multiple signaling networks linking metabolic and oncogenic pathways. Aberrant PCK1 expression results in the activation of oncogenic pathways, accompanied by metabolic reprogramming, to maintain tumorigenesis. In this review, we summarize the mechanisms underlying PCK1 expression and regulation, and clarify the crosstalk between aberrant PCK1 expression, metabolic rewiring, and signaling pathway activation. In addition, we highlight the clinical relevance of PCK1 and its value as a putative cancer therapeutic target.

1314

SPINOPHILIN (SPN, PPP1R9B or NEURABIN-2) is a multifunctional protein that regulates protein-protein interactions in different cell signaling pathways. SPN is also one of the regulatory subunits of protein phosphatase 1 (PP1), implicated in the dephosphorylation of retinoblastoma protein (pRB) during cell cycle. The SPN gene has been described as a tumor suppressor in different human tumor contexts, in which low levels of SPN are correlated with a higher grade and worse prognosis. In addition, mutations of the SPN protein have been reported in human tumors. Recently, an oncogenic mutation of SPN, A566V, was described, which affects both the SPN-PP1 interaction and the phosphatase activity of the holoenzyme, and promotes p53-dependent tumorigenesis by increasing the cancer stem cell (CSC) pool in breast tumors. Thus, the loss or mutation of SPN could be late events that promotes tumor progression by increasing the CSC pool and, eventually, the malignant behavior of the tumor.

1419

The insulin-like growth factor (IGF) axis plays important roles in cancer development and metastasis. The type 1 IGF receptor (IGF-1R) is a key member in the IGF axis and has long been recognized for its oncogenic role in multiple cancer lineages. Here we review the occurrence of IGF-1R aberrations and activation mechanisms in cancers, which justify the development of anti-IGF-1R therapies. We describe the therapeutic agents available for IGF-1R inhibition, with focuses on the recent or ongoing pre-clinical and clinical studies. These include antisense oligonucleotide, tyrosine kinase inhibitors and monoclonal antibodies which may be conjugated with cytotoxic drug. Remarkably, simultaneous targeting of IGF-1R and several other oncogenic vulnerabilities has shown early promise, highlighting the potential benefits of combination therapy. Further, we discuss the challenges in targeting IGF-1R so far and new concepts to improve therapeutic efficacy such as blockage of the nuclear translocation of IGF-1R.

1438

Abnormal gene expression plays key role in cancer development. A core promoter is located around the transcriptional start site. Through interaction between core promoter sequences and transcriptional factors, core promoter controls transcriptional initiation. We hypothesized that in cancer, core promoter sequences could be mutated to interfere the interaction with transcriptional factors, resulting in altered transcriptional initiation and abnormal gene expression and cancer development. We used triple-negative breast cancer (TNBC) as a model to test our hypothesis. We collected genome-wide core promoter variants from 279 TNBC genomes. After extensive filtering of normal genomic polymorphism, we identified 19,427 recurrent somatic variants in 1,238 core promoters of 1,274 genes and 1,694 recurrent germline variants in 272 core promoters of 294 genes. Many of the affected genes were oncogenes and tumor suppressors. Analysis of RNA-seq data from the same patient cohort identified increased or decreased gene expression in 439 somatic and 85 germline variants-affected genes, and the results were validated by luciferase reporter assay. By comparing with the core promoter variation data from 610 unclassified breast cancer, we observed that core promoter variants in TNBC were highly TNBC-specific. We further identified the drugs targeting the genes with core promoter variation. Our study demonstrates that core promoter is highly mutable in cancer, and can play etiological roles in TNBC and other types of cancer through influencing transcriptional initiation.

1362

Osteosarcoma is a malignant bone tumor that commonly occurs in the pediatric population. Despite the use of chemotherapy and surgery, metastasis remains to be the leading cause of death in patients with osteosarcoma. We have previously reported that cytoplasmic mislocalization of p27 is associated with a poor outcome in osteosarcoma. In this study, we further show that lysyl oxidase (LOX) expression was associated with p27 mislocalization. LOX is an enigmatic molecule that acts as a tumor suppressor or a metastatic promoter; however, its role in osteosarcoma is still unclear. Hence, we performed both in vitro and in vivo analyses to dissect the role of LOX in osteosarcoma. The result of our survival analysis indicated that LOX expression significantly correlated with a poor outcome in osteosarcoma with or without controlling for the initial metastasis status (P < 0.05). Functionally, we found that higher LOX expression promoted osteosarcoma cell proliferation, migration, and invasiveness in vitro and produced a higher number of mice with pulmonary metastases in an orthotopic xenograft mouse model. Mechanistically, phospho-FAK was increased in osteosarcoma cells with high LOX expression. Our results further showed that FAK inhibition significantly reduced tumor cell proliferation and migration in vitro as well as LOX-mediated metastasis in mice. Together, our findings suggest that there is a novel link between p27 mislocalization and LOX expression. LOX plays a pivotal role in osteosarcoma metastasis by upregulating FAK phosphorylation. FAK inhibition may constitute a promising therapeutic strategy to reduce the development of metastasis in osteosarcoma with LOX overexpression.

1348

Market drugs, such as Food and Drug Administration (FDA) or European Medicines Agency (EMA) -approved drugs for specific indications provide opportunities for repurposing for newer therapeutics. This potentially saves resources invested in clinical trials that verify drug safety and tolerance in humans prior to alternative indication approval. Protein arginine methyltransferase 5 (PRMT5) overexpression has been linked to promoting the tumor phenotype in several cancers, including pancreatic ductal adenocarcinoma (PDAC), colorectal cancer (CRC), and breast cancer (BC), making PRMT5 an important target for cancer therapy. Previously, we showed that PRMT5-mediated methylation of the nuclear factor (NF) -κB, partially contributes to its constitutive activation observed in cancers. In this study, we utilized an AlphaLISA-based high-throughput screening method adapted in our lab, and identified one FDA-approved drug, Candesartan cilexetil (Can, used in hypertension treatment) and one EMA-approved drug, Cloperastine hydrochloride (Clo, used in cough treatment) that had significant PRMT5-inhibitory activity, and their anti-tumor properties were validated using cancer phenotypic assays in vitro. Furthermore, PRMT5 selective inhibition of methyltransferase activity was confirmed by reduction of both NF-κB methylation and its subsequent activation upon drug treatment. Using in silico prediction, we identified critical residues on PRMT5 targeted by these drugs that may interfere with its enzymatic activity. Finally, Clo and Can treatment have exhibited marked reduction in tumor growth in vivo. Overall, we provide basis for pursuing repurposing Clo and Can as anti-PRMT5 cancer therapies. Our study offers potential safe and fast repurposing of previously unknown PRMT5 inhibitors into clinical practice.

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