Osr2 functions as a biomechanical checkpoint to aggravate CD8+ T cell exhaustion in tumor.

Alterations in extracellular matrix (ECM) architecture and stiffness represent hallmarks of cancer. Whether the biomechanical property of ECM impacts the functionality of tumor-reactive CD8+ T cells remains largely unknown. Here, we reveal that the transcription factor (TF) Osr2 integrates biomechanical signaling and facilitates the terminal exhaustion of tumor-reactive CD8+ T cells. Osr2 expression is selectively induced in the terminally exhausted tumor-specific CD8+ T cell subset by coupled T cell receptor (TCR) signaling and biomechanical stress mediated by the Piezo1/calcium/CREB axis. Consistently, depletion of Osr2 alleviates the exhaustion of tumor-specific CD8+ T cells or CAR-T cells, whereas forced Osr2 expression aggravates their exhaustion in solid tumor models. Mechanistically, Osr2 recruits HDAC3 to rewire the epigenetic program for suppressing cytotoxic gene expression and promoting CD8+ T cell exhaustion. Thus, our results unravel Osr2 functions as a biomechanical checkpoint to exacerbate CD8+ T cell exhaustion and could be targeted to potentiate cancer immunotherapy.

Bimodal regulation of the PRC2 complex by USP7 underlies tumorigenesis.

Although overexpression of EZH2, a catalytic subunit of the polycomb repressive complex 2 (PRC2), is an eminent feature of various cancers, the regulation of its abundance and function remains insufficiently understood. We report here that the PRC2 complex is physically associated with ubiquitin-specific protease USP7 in cancer cells where USP7 acts to deubiquitinate and stabilize EZH2. Interestingly, we found that USP7-catalyzed H2BK120ub1 deubiquitination is a prerequisite for chromatin loading of PRC2 thus H3K27 trimethylation, and this process is not affected by H2AK119 ubiquitination catalyzed by PRC1. Genome-wide analysis of the transcriptional targets of the USP7/PRC2 complex identified a cohort of genes including FOXO1 that are involved in cell growth and proliferation. We demonstrated that the USP7/PRC2 complex drives cancer cell proliferation and tumorigenesis in vitro and in vivo. We showed that the expression of both USP7 and EZH2 elevates during tumor progression, corresponding to a diminished FOXO1 expression, and the level of the expression of USP7 and EZH2 strongly correlates with histological grades and prognosis of tumor patients. These results reveal a dual role for USP7 in the regulation of the abundance and function of EZH2, supporting the pursuit of USP7 as a therapeutic target for cancer intervention.

MicroRNA-455-3p mediates GATA3 tumor suppression in mammary epithelial cells by inhibiting TGF-ß signaling.

GATA3 is a basic and essential transcription factor that regulates many pathophysiological processes and is required for the development of mammary luminal epithelial cells. Loss-of-function GATA3 alterations in breast cancer are associated with poor prognosis. Here, we sought to understand the tumor-suppressive functions GATA3 normally performs. We discovered a role for GATA3 in suppressing epithelial-to-mesenchymal transition (EMT) in breast cancer by activating miR-455-3p expression. Enforced expression of miR-455-3p alone partially prevented EMT induced by transforming growth factor ß (TGF-ß) both in cells and tumor xenografts by directly inhibiting key components of TGF-ß signaling. Pathway and biochemical analyses showed that one miRNA-455-3p target, the TGF-ß-induced protein ZEB1, recruits the Mi-2/nucleosome remodeling and deacetylase (NuRD) complex to the promotor region of miR-455 to strictly repress the GATA3-induced transcription of this microRNA. Considering that ZEB1 enhances TGF-ß signaling, we delineated a double-feedback interaction between ZEB1 and miR-455-3p, in addition to the repressive effect of miR-455-3p on TGF-ß signaling. Our study revealed that a feedback loop between these two axes, specifically GATA3-induced miR-455-3p expression, could repress ZEB1 and its recruitment of NuRD (MTA1) to suppress miR-455, which ultimately regulates TGF-ß signaling. In conclusion, we identified that miR-455-3p plays a pivotal role in inhibiting the EMT and TGF-ß signaling pathway and maintaining cell differentiation. This forms the basis of that miR-455-3p might be a promising therapeutic intervention for breast cancer.

PHD finger protein 1 (PHF1) is a novel reader for histone H4R3 symmetric dimethylation and coordinates with PRMT5-WDR77/CRL4B complex to promote tumorigenesis.

Histone post-translational modifications regulate chromatin structure and function largely through interactions with effector proteins that often contain multiple histone-binding domains. PHF1 [plant homeodomain (PHD) finger protein 1], which contains two kinds of histone reader modules, a Tudor domain and two PHD fingers, is an essential factor for epigenetic regulation and genome maintenance. While significant progress has been made in characterizing the function of the Tudor domain, the roles of the two PHD fingers are poorly defined. Here, we demonstrated that the N-terminal PHD finger of PHF1 recognizes symmetric dimethylation of H4R3 (H4R3me2s) catalyzed by PRMT5-WDR77. However, the C-terminal PHD finger of PHF1, instead of binding to modified histones, directly interacts with DDB1, the main component of the CUL4B-Ring E3 ligase complex (CRL4B), which is responsible for H2AK119 mono-ubiquitination (H2AK119ub1). We showed that PHF1, PRMT5-WDR77, and CRL4B reciprocally interact with one another and collaborate as a functional unit. Genome-wide analysis of PHF1/PRMT5/CUL4B targets identified a cohort of genes including E-cadherin and FBXW7, which are critically involved in cell growth and migration. We demonstrated that PHF1 promotes cell proliferation, invasion, and tumorigenesis in vivo and in vitro and found that its expression is markedly upregulated in a variety of human cancers. Our data identified a new reader for H4R3me2s and provided a molecular basis for the functional interplay between histone arginine methylation and ubiquitination. The results also indicated that PHF1 is a key factor in cancer progression, supporting the pursuit of PHF1 as a target for cancer therapy.

Over-expression of microRNA-375 inhibits papillary thyroid carcinoma cell proliferation and induces cell apoptosis by targeting ERBB2.

MicroRNAs (miRs) played important roles in the cell proliferation, apoptosis and other biological processes in cancer. In the present study we found that miR-375 was significantly down-regulated in human papillary thyroid carcinoma (PTC) tissues and cell lines. In this study we try to investigate the biological activity of miR-375 in human PTC cells and try to find the potential target of miR-375. Our study indicated that over-expression of miR-375 could inhibit the PTC cells proliferation and this inhibition was caused by the induction of cell apoptosis. In vivo animal study indicated that over-expression of miR-375 could significantly decrease the migration and invasion of human PTC cell in vivo. These results exhibit over-expression of miR-375 in human PTC cells could inhibit the process of human PTC. Further study demonstrated ERBB2 was a direct target of miR-375, over-expression of miR-375 decrease the both mRNA and protein expression of ERBB2 in human PTC cells. These data indicate miR-375 play important roles in the process and development of human PTC. These finds suggested that appropriate application of miR-375 regulation might be a new sight for the treatment of human PTC in the future.

[Logistic regression analysis for factors affecting the successful rate of nano-carbon in sentinel lymph node biopsy].

OBJECTIVE: To explore the factors affecting the successful rate of nano-carbon in sentinel lymph node biopsy.
 METHODS: A total of 270 patients with breast cancer, who were treated in First Affilitated Hospital of Henan University of Science and Technology from January 2013 to March 2015, were chosen and given sentinel lymph node biopsy (SLN) with nano-carbon, and the influencial factors were examined by logistic analysis.
 RESULTS: Successful rate of biopsy, accuracy, sensitivity and false negative rate was 92.2%, 97.6%, 93.1% and 6.8%, respectively. Age, primary tumor lesions, body mass index, axillary lymph node status, number of SLN and pathological grade were the factors affetcing successful biopsy (all P<0.05), and body mass index, age, and number of SLN were three independent factors affecting the successful rate of biopsy (all P<0.05). The history of biopsy, tumor location, affected sides, injection sites and chemotherapy showed little effect on the successful rate of biopsy (all P> 0.05).
 CONCLUSION: Nano-carbon tracer method is a reliable method in sentinel lymph node biopsy. The body mass index, age, and number of lymph node metastasis greatly impact the successful rate of biopsy.

Mechanical properties and energy damage evolution mechanism of fiber-reinforced cemented sulfur tailings backfill under uniaxial compression.

This paper studies mechanical properties and energy damage evolution of fiber-reinforced cemented sulfur tailings (CSTB) backfill. The effects of fiber length and fiber content on the stress, toughness and failure properties of the CSTB were systematically revealed. In addition, the energy index evolution law was studied, and the energy damage evolution mechanism of CSTB was revealed. The results show that the deformation failure of fiber-reinforced CSTB mainly goes through four stages: initial crack compaction, linear elastic deformation, yield failure and post-peak failure. The peak stress and residual stress of the CSTB firstly increase and then decrease with the increase of fiber content and the addition of fiber can promote the change from brittle failure to ductile failure of the CSTB. Adding appropriate amount of fiber can improve the toughness of CSTB, and the influence degree of fiber length on the toughness index of CSTB is 6mm>12mm>3mm. The total strain energy increases linearly along the variation of fiber content, while the elastic strain energy and dissipated energy increase exponentially at the peak stress point. In the process of CSTB deformation and failure, "gentle-linear growth-slow growth-rapid decline" is for elastic strain energy, while "gentle-slow growth-rapid growth-linear growth" is for dissipation energy. The damage and failure of CSTB mainly experienced four stages: initial damage, slow growth of damage, accelerated damage and damage failure, and the damage evolution curve also showed the changing characteristics of "gentle-slow growth-rapid growth-linear growth". The CSTB without added fiber showed obvious "Y-type" and "linear-type" shear failure characteristics and the phenomenon of shear cracks penetrating the backfill appeared. No big shear crack occur when it is damaged, showing that the fiber addition restrain the crack growth and improve the overall crack resistance of the CSTB. Hydration products are obviously distributed on the surface of the fiber, which indicates that the fiber will be evenly dispersed in the CSTB and form a certain bonding force with the cement-tailings matrix, thus improving the overall mechanical properties of the CSTB.

High-spectral-resolution characterization of broadband high-efficiency reflection gratings.

An optical characterization method with high spectral resolution for broadband, multilayer dielectric gratings working at the -1st reflection order is demonstrated in this paper. The diffraction-efficiency measurement setup for the broadband gratings with high efficiencies mainly consists of a double-light-path system with a monochromator as the illumination source and an automatic rotation stage for incident and diffraction angles adjustment. Two typical practical difficulties, namely (1) the mismatch between the spot size of diffracted light and the limited detector aperture and (2) the shared propagation path between the incident and diffracted light at the Littrow angle, were well solved. A fabricated multilayer dielectric grating was measured on the established measurement setup. Diffraction efficiencies greater than 90% in the wavelength range from 763 to 852 nm were obtained with an average relative deviation less than 1.0%. At the moment, the wavelength resolution is 1 nm and the angle resolution is 0.2 deg. The high-resolution broadband diffraction spectrometry testing method is applicable to characterizing broadband pulse compression gratings in the laser systems.

Experimental study on time-dependent rheological properties and mechanical performance of cemented fine tailings backfill mixed with polypropylene fiber.

By preparing fine tailings slurry with different mass concentration and fiber content, the rheological parameters of slurry with different fiber content and curing time were tested. In addition, the influence law of fiber content and curing time on compressive strength was analyzed through the prepared fine tailings backfill samples, and the microstructure characteristics of fine tailings backfill were further studied. The results show that when the fiber content is 0.2 ~ 1.2%, the yield stress and plastic viscosity of the slurry increase with the increase of fiber content, and the thixotropy of the slurry also shows the same change characteristics. The bridge effect of fiber makes it easier for forming network structure, which increase the slurry rheology. When the curing time ranges from 0 h to 2.5 h, the increasing of curing time leads to the increasing trend of rheological parameters, and also increases the thixotropy of slurry. However, the increase of rheological parameters will continuously decrease when the curing time exceeds 1 h, indicating that the influence of curing time on yield stress and thixotropy will gradually weaken with the continuous extension of curing time. When the curing age increases from 3 to 56 days, the compressive strength of the fine tailings backfill increases with the curing age, but the increasing range of compressive strength decreases gradually. When the fiber content ranges from 0.2 to 1.2%, the compressive strength of backfill increases first and then decreases with the increase of fiber content, and reaches the maximum value when the fiber content is 0.6%. The extension of curing time reduces the generation of large-scale pore structure, which promotes the formation of more compact microstructure of backfill.

Network Pharmacology and Molecular Docking Analysis on Mechanisms of Scutellariae Radix in the Treatment of Cerebral Ischemia-reperfusion Injury.

BACKGROUND: Multiple brain disorders are treated by Scutellaria Radix (SR), including cerebral ischemia-reperfusion (CI/R). However, more studies are needed to clarify the molecular mechanism of SR for CI/R. METHODS: The active substances and potential targets of SR and CI/R-related genes were obtained through public databases. Overlapping targets of SR and CI/R were analyzed using proteinprotein interaction (PPI) networks. GO and KEGG enrichment analyses were performed to predict the pathways of SR against CI/R, and the key components and targets were screened for molecular docking. The results of network pharmacology analysis were verified using in vitro experiments. RESULTS: 15 components and 64 overlapping targets related to SR and CI/R were obtained. The top targets were AKT1, IL-6, CAS3, TNF, and TP53. These targets have been studied by GO and KEGG to be connected to a number of signaling pathways, including MAPK, PI3K-Akt pathway, and apoptosis. Molecular docking and cell experiments helped to further substantiate the network pharmacology results. CONCLUSION: The active compound of SR was able to significantly decrease the apoptosis of HT22 cells induced by OGD/R. This finding suggests that SR is a potentially effective treatment for CI/R by modulating the MAPK and PI3K-Akt pathways.

SPTAN1/NUMB axis senses cell density to restrain cell growth and oncogenesis through Hippo signaling.

The loss of contact inhibition is a key step during carcinogenesis. The Hippo-Yes-associated protein (Hippo/YAP) pathway is an important regulator of cell growth in a cell density-dependent manner. However, how Hippo signaling senses cell density in this context remains elusive. Here, we report that high cell density induced the phosphorylation of spectrin α chain, nonerythrocytic 1 (SPTAN1), a plasma membrane-stabilizing protein, to recruit NUMB endocytic adaptor protein isoforms 1 and 2 (NUMB1/2), which further sequestered microtubule affinity-regulating kinases (MARKs) in the plasma membrane and rendered them inaccessible for phosphorylation and inhibition of the Hippo kinases sterile 20-like kinases MST1 and MST2 (MST1/2). WW45 interaction with MST1/2 was thereby enhanced, resulting in the activation of Hippo signaling to block YAP activity for cell contact inhibition. Importantly, low cell density led to SPTAN1 dephosphorylation and NUMB cytoplasmic location, along with MST1/2 inhibition and, consequently, YAP activation. Moreover, double KO of NUMB and WW45 in the liver led to appreciable organ enlargement and rapid tumorigenesis. Interestingly, NUMB isoforms 3 and 4, which have a truncated phosphotyrosine-binding (PTB) domain and are thus unable to interact with phosphorylated SPTAN1 and activate MST1/2, were selectively upregulated in liver cancer, which correlated with YAP activation. We have thus revealed a SPTAN1/NUMB1/2 axis that acts as a cell density sensor to restrain cell growth and oncogenesis by coupling external cell-cell contact signals to intracellular Hippo signaling.

2,5-Dimethyl Celecoxib Inhibits Proliferation and Cell Cycle and Induces Apoptosis in Glioblastoma by Suppressing CIP2A/PP2A/Akt Signaling Axis.

2,5-Dimethyl-celecoxib (DMC) is a close structural analog of the selective COX-2 inhibitor celecoxib that lacks COX-2-inhibitory function. Thus, DMC is a promising drug for anti-tumor. In this study, we evaluated the efficacy and the molecular basis of DMC in the treatment of human glioblastoma multiforme (GBM). DMC inhibited the growth and proliferation of GBM cell lines (LN229, A172, U251, and U87MG) in a dose-dependent manner (P < 0.001). In GBM cells treated with DMC, detection by flow cytometry showed cell cycle arrest, and proteins involved in cell cycle such as P21 were increased. Compared with control group, Annexin-V/PI-staining in DMC-treatment group was increased, indicating that DMC could induce apoptosis in GBM cells. Also, associated proteins including cleaved caspase 3 and cleaved PARP-1 were increased. It was further explored whether DMC blocked cell cycle and induced apoptosis in GBM cells through CIP2A/PP2A/AKT signaling pathway. After treatment of DMC, the phosphorylation of Akt was reduced while the total Akt level was not affected. DMC suppressed the expression of CIP2A in a time-dependent manner, while the CIP2A overexpression group reversed cell cycle and apoptotic protein expression led by DMC. Finally, in a xenograft model in nude mice using LN229 cells, DMC suppressed tumor growth. These findings proved that DMC could block cell cycle and induce apoptosis in GBM cells by suppressing CIP2A/PP2A/Akt signaling axis, which indicated that DMC could be an effective option for GBM treatment.

Digoxin exerts anticancer activity on human nonsmall cell lung cancer cells by blocking PI3K/Akt pathway.

Lung cancer remains the leading cause of cancer mortality because of its metastatic potential and high malignancy. The discovery of new applications for old drugs is a shortcut for cancer therapy. We recently investigated the antitumor effect of digoxin, a well-established drug for treating heart failure, against nonsmall cell lung cancer A549 and H1299 cells. Digoxin inhibited the proliferation and colony-forming ability of the two cell lines and arrested the cell cycle at the G0/G1 phase in A549 cells and the G2/M phase in H1299 cells. Mitochondria-mediated apoptosis was induced in A549 cells but not in H1299 cells after treatment with digoxin. Moreover, digoxin inhibited the migration, invasion, adhesion and epithelial-mesenchymal transition of A549 and H1299 cells. Autophagy was induced in both cell lines after treatment with digoxin, with an increase in autophagosome foci. In addition, digoxin inhibited the phosphorylation of Akt, mTOR and p70S6K, signaling molecules of the PI3K/Akt pathway that are known to be involved in tumor cell survival, proliferation, metastasis and autophagy. Our findings suggest that digoxin has the potential to be used for therapy for human nonsmall cell lung cancer, but further evidence is required.

Multifaceted anti-colorectal tumor effect of digoxin on HCT8 and SW620 cells in vitro.

BACKGROUND: Colorectal cancer (CRC) is one of the leading causes of cancer death worldwide. Novel drugs for CRC therapy are urgently needed. Digoxin has been in clinical use for treatment of heart failure and atrial arrhythmias for many years. Fragmentary reports suggested that digoxin might have antitumor efficacy on CRC. Here, we aimed to investigate the antitumor effect of digoxin on human CRC cells and the underlying mechanism. METHODS: Cell viability was determined using 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay and plate colony formation assay. The effects of digoxin on cell-cycle distribution and apoptosis were analysed by flow cytometry. The anti-metastatic effect on tumor cells was determined by wound-healing assay and transwell assay. Anti-angiogenic effect was examined by determining the inhibition against proliferation, migration, and tube formation of human umbilical vein endothelial cells (HUVECs). Mechanism study was performed by Western blot, enzyme-linked immunosorbent assay (ELISA), and gelatin-zymography assay. RESULTS: Digoxin potently inhibited cell proliferation, induced G1-phase and G2/M-phase arrest in colorectal-cancer HCT8 and SW620 cells, respectively. No obvious apoptosis was observed in the treated cells. Anti-metastatic activities were shown on HCT8 cells by inhibiting the migration and invasion. Meanwhile, the expression of MMP2, MMP9, and phosphorylated Integrinß1 were decreased. Digoxin inhibited the proliferation, migration, and tube formation of HUVECs and reduced HIF1α expression and vascular endothelial growth factor A (VEGF-A) secretion in HCT8 cells, suggesting anti-angiogenic activity. Furthermore, digoxin significantly reversed ABCB1-mediated multidrug resistance on SW620/Ad300 cells. CONCLUSION: Our findings suggest that digoxin has the potential to be applied as an antitumor drug via inhibiting proliferation and metastasis as well as reversing the ABCB1-mediated multidrug resistance of colorectal cancer.

PHF20L1 as a H3K27me2 reader coordinates with transcriptional repressors to promote breast tumorigenesis.

TUDOR domain-containing proteins (TDRDs) are chiefly responsible for recognizing methyl-lysine/arginine residue. However, how TDRD dysregulation contributes to breast tumorigenesis is poorly understood. Here, we report that TUDOR domain-containing PHF20L1 as a H3K27me2 reader exerts transcriptional repression by recruiting polycomb repressive complex 2 (PRC2) and Mi-2/nucleosome remodeling and deacetylase (NuRD) complex, linking PRC2-mediated methylation and NuRD-mediated deacetylation of H3K27. Furthermore, PHF20L1 was found to serve as a potential MYC and hypoxia-driven oncogene, promoting glycolysis, proliferation, and metastasis of breast cancer cells by directly inhibiting tumor suppressors such as HIC1, KISS1, and BRCA1. PHF20L1 expression was also strongly correlated with higher histologic grades of breast cancer and markedly up-regulated in several cancers. Meanwhile, Phf20l1 deletion not only induces growth retardation and mammary ductal outgrowth delay but also inhibits tumorigenesis in vivo. Our data indicate that PHF20L1 promotes tumorigenesis, supporting the pursuit of PHF20L1 as a target for cancer therapy.

GATA3 recruits UTX for gene transcriptional activation to suppress metastasis of breast cancer.

GATA3 has emerged as a prominent transcription factor required for maintaining mammary-gland homeostasis. GATA3 loss is associated with aggressive breast cancer development, but the mechanism by which breast cancer is affected by the loss of GATA3 function remains unclear. Here, we report that GATA3 expression is positively correlated with the expression of UTX, a histone H3K27 demethylase contained in the MLL4 methyltransferase complex, and that GATA3 recruits the chromatin-remodeling MLL4 complex and interacts directly with UTX, ASH2L, and RBBP5. Using RNA sequencing and chromatin immunoprecipitation and sequencing, we demonstrate that the GATA3/UTX complex synergistically regulates a cohort of genes including Dicer and UTX, which are critically involved in the epithelial-to-mesenchymal transition (EMT). Our results further show that the GATA3-UTX-Dicer axis inhibits EMT, invasion, and metastasis of breast cancer cells in vitro and the dissemination of breast cancer in vivo. Our study implicates the GATA3-UTX-Dicer axis in breast cancer metastasis and provides new mechanistic insights into the pathophysiological function of GATA3.

Regulation of EZH2 by SMYD2-Mediated Lysine Methylation Is Implicated in Tumorigenesis.

The histone methyl transferase enhancer of zeste homolog 2 (EZH2) is a master transcriptional regulator involved in histone H3 lysine 27 trimethylation. We aimed to elucidate the precise post-translational regulations of EZH2 and their role in cancer pathogenesis. Here, we show that SET and MYND domain containing 2 (SMYD2) directly methylates EZH2 at lysine 307 (K307) and enhances its stability, which can be relieved by the histone H3K4 demethylase lysine-specific demethylase 1 (LSD1). SMYD2 is critical for EZH2 function in repressing a cohort of genes governing several cancer-associated pathways. In addition, SMYD2 promotes breast cancer cell proliferation, epithelial-mesenchymal transition, and invasion through EZH2 K307 methylation, and it is markedly upregulated in various human cancers. Our data suggest that dynamic crosstalk between SMYD2-mediated EZH2 methylation plays an important role in fine-tuning EZH2 functions in chromatin recruitment and transcriptional repression.

BRMS1 coordinates with LSD1 and suppresses breast cancer cell metastasis.

Breast carcinoma metastasis suppressor gene 1 (BRMS1) encodes an inhibitor of metastasis and is reported in many types of tumor metastasis. However, the mechanism of BRMS1-mediated inhibition of breast cancer metastasis at the transcriptional level remains elusive. Here, we identified using affinity purification and mass spectrometry (MS) that BRMS1 is an integral component of the LSD1/CoREST corepressor complex. Analysis of the BRMS1/LSD1 complex using high-throughput RNA deep sequencing (RNA-seq) identified a cohort of target genes such as VIM, INSIG2, KLK11, MRPL33, COL5A2, OLFML3 and SLC1A1, some of which are metastasis-related. Our results have showed that BRMS1 together with LSD1 are required for inhibition of breast cancer cell migration and invasion. Collectively, these findings demonstrate that BRMS1 executes transcriptional suppression of breast cancer metastasis by associating with the LSD1 and thus can be targeted for breast cancer therapy.

The Homeotic Protein SIX3 Suppresses Carcinogenesis and Metastasis through Recruiting the LSD1/NuRD(MTA3) Complex.

The homeodomain transcription factor SIX3 was recently reported to be a negative regulator of the Wnt pathway and has an emerging role in cancer. However, how SIX3 contributes to tumorigenesis and metastasis is poorly understood. METHODS: We employed affinity purification and mass spectrometry (MS) to identify the proteins physically associated with SIX3. Genome-wide analysis of the SIX3/LSD1/NuRD(MTA3) complex using a chromatin immunoprecipitation-on-chip approach identified a cohort of target genes including WNT1 and FOXC2, which are critically involved in cell proliferation and epithelial-to-mesenchymal transition. Also, we used flow cytometry, growth curve analysis, EdU incorporation assay, colony formation assays, trans-well invasion assays, immunohistochemical staining and in vivo bioluminescence assay to investigate the function of SIX3 in tumorigenesis. RESULTS: We demonstrate that the SIX3/LSD1/NuRD(MTA3) complex inhibits carcinogenesis in breast cancer cells and suppresses metastasis in breast cancer. SIX3 expression is downregulated in various human cancers and high SIX3 is correlated with improved prognosis. CONCLUSION: Our study revealed an important mechanistic link between the loss of function of SIX3 and tumor progression, identified a molecular basis for the opposing actions of MTA1 and MTA3, and may provide new potential prognostic indicators and targets for cancer therapy.

LSD1 coordinates with the SIN3A/HDAC complex and maintains sensitivity to chemotherapy in breast cancer.

Lysine-specific demethylase 1 (LSD1) was the first histone demethylase identified as catalysing the removal of mono- and di-methylation marks on histone H3-K4. Despite the potential broad action of LSD1 in transcription regulation, recent studies indicate that LSD1 may coordinate with multiple epigenetic regulatory complexes including CoREST/HDAC complex, NuRD complex, SIRT1, and PRC2, implying complicated mechanistic actions of this seemingly simple enzyme. Here, we report that LSD1 is also an integral component of the SIN3A/HDAC complex. Transcriptional target analysis using ChIP-on-chip technology revealed that the LSD1/SIN3A/HDAC complex targets several cellular signalling pathways that are critically involved in cell proliferation, survival, metastasis, and apoptosis, especially the p53 signalling pathway. We have demonstrated that LSD1 coordinates with the SIN3A/HDAC complex in inhibiting a series of genes such as CASP7, TGFB2, CDKN1A(p21), HIF1A, TERT, and MDM2, some of which are oncogenic. Our experiments also found that LSD1 and SIN3A are required for optimal survival and growth of breast cancer cells while also essential for the maintenance of epithelial homoeostasis and chemosensitivity. Our data indicate that LSD1 is a functional alternative subunit of the SIN3A/HDAC complex, providing a molecular basis for the interplay of histone demethylation and deacetylation in chromatin remodelling, and suggest that the LSD1/SIN3A/HDAC complex could be a target for breast cancer therapeutic strategies.