Spatial interaction and functional status of CD68+SHP2+ macrophages in tumor microenvironment correlate with overall survival of NSCLC.

Background: Tumor-associated macrophages (TAMs) constitute a plastic and heterogeneous cell population of the tumor microenvironment (TME) that can regulate tumor proliferation and support resistance to therapy, constituting promising targets for the development of novel anticancer agents. Our previous results suggest that SHP2 plays a crucial role in reprogramming the phenotype of TAMs. Thus, we hypothesized that SHP2+ TAM may predict the treatment efficacy of non-small cell lung cancer NSCLC patients as a biomarker. Methods: We analyzed cancer tissue samples from 79 NSCLC patients using multiplex fluorescence (mIF) staining to visualize various SHP-2+ TAM subpopulations (CD68+SHP2+, CD68+CD86+, CD68 + 206+, CD68+ CD86+SHP2+, CD68+ CD206+SHP2+) and T cells (CD8+ Granzyme B +) of immune cells. The immune cells proportions were quantified in the tumor regions (Tumor) and stromal regions (Stroma), as well as in the overall tumor microenvironment (Tumor and Stroma, TME). The analysis endpoint was overall survival (OS), correlating them with levels of cell infiltration or effective density. Cox regression was used to evaluate the associations between immune cell subsets infiltration and OS. Correlations between different immune cell subsets were examined by Spearman's tests. Results: In NSCLC, the distribution of different macrophage subsets within the TME, tumor regions, and stroma regions exhibited inconsistency. The proportions of CD68+ SHP2+ TAMs (P < 0.05) were higher in tumor than in stroma. And the high infiltration of CD68+SHP2+ TAMs in tumor areas correlated with poor OS (P < 0.05). We found that the expression level of SHP2 was higher in M2-like macrophages than in M1-like macrophages. The CD68+SHP2+ subset proportion was positively correlated with the CD68+CD206+ subset within TME (P < 0.0001), tumor (P < 0.0001) and stroma (P < 0.0001). Conclusions: The high infiltration of CD68+SHP2+ TAMs predict poor OS in NSCLC. Targeting SHP2 is a potentially effective strategy to inhibit M2-phenotype polarization. And it provides a new thought for SHP2 targeted cancer immunotherapy.

Aberrant ROS Served as an Acquired Vulnerability of Cisplatin-Resistant Lung Cancer.

Lung cancer has become a global health issue in recent decades. Approximately 80-85% of cases are non-small-cell lung cancer (NSCLC). Despite the high rate of resistance, cisplatin-base chemotherapy is still the main treatment for NSCLC patients. Thus, overcoming cisplatin resistance is urgently needed in NSCLC therapy. In this study, we identify NADPH metabolism and reactive oxygen species (ROS) levels as the main causes accounting for cisplatin resistance. Based on a small panel consisting of common chemotherapy drugs or compounds, APR-246 is proved to be an effective compound targeting cisplatin-resistant NSCLC cells. APR-246 specially inhibits proliferation and colony formation of cisplatin-resistant cells. In details, APR-246 can significantly cause G0/G1 accumulation and S phase arrest of cisplatin resistant cells and gives rise to severe mitochondria dysfunction as well as elevated apoptosis. Further study proves that it is the aberrant ROS levels as well as NRF2/SLC7A11/GSH axis dysfunction accounting for the specific antitumor effects of APR-246. Scavenging ROS with N-acetylcysteine (NAC) disrupts the inhibitory effect of APR-246 on cisplatin-resistant cells. Mechanistically, NRF2 is specifically degraded by the proteasome following its own ubiquitylation in APR-246-treated cisplatin-resistant cells, which in turn decreases NRF2/SLC7A11/GSH axis activity. Our study provides new insights into the biology driving cisplatin resistance of lung cancer and highlights APR-246 as a potential therapeutic reagent for overcoming cisplatin resistance.

A novel use for an old drug: resistance reversal in Candida albicans by combining dihydroartemisinin with fluconazole.

Aim: To investigate the effects of dihydroartemisinin combined with fluconazole against C. albicans in vitro and to explore the underlying mechanisms. Materials & methods: Checkerboard microdilution assay and time-kill curve method were employed to evaluate the static and dynamic antifungal effects against C. albicans. Reactive oxygen species (ROS) was measured by a fluorescent probe. Results: Combination of dihydroartemisinin and fluconazole exerted potent synergy against planktonic cells and biofilms of fluconazole-resistant C. albicans, with the fractional inhibitory concentration index values less than 0.07. A potent fungistatic activity of this drug combination could still be observed after 18 h. The accumulation of ROS induced by the drug combination might contribute to the synergy. Conclusion: Dihydroartemisinin reversed the resistance of C. albicans to fluconazole.

Lay abstract Patients with weakened immune system often suffer from C. albicans infections. C. albicans is a common fungus. Fluconazole is a widely used antifungal drug owing to its low price and few side effects. Unfortunately, fluconazole is gradually losing its effect against C. albicans due to the constantly emerging resistance in C. albicans. Interestingly, in this study a combined use of fluconazole and an old antimalarial agent restored the effect of fluconazole against resistant C. albicans. The antimalarial drug we used is dihydroartemisinin, with low price, high safety and multiple biological activities, which originates from a traditional Chinese medicine. Our study also presented that this drug combination generated abundant reactive oxygen, which might account for the effect. The drug combination would be expected to be used for treating C. albicans infections.

EPB41 suppresses the Wnt/ß-catenin signaling in non-small cell lung cancer by sponging ALDOC.

Despite advancements in therapeutic options, the overall prognosis for non-small-cell lung cancer (NSCLC) remains poor. Further exploration of the etiology and targets for novel treatments is crucial for managing NSCLC. In this study, we revealed the significant potential of EPB41 for inhibiting NSCLC proliferation, invasion and metastasis in vitro and in vivo. Consistent with its tumor suppressor role in NSCLC, the expression of EPB41 in NSCLC specimens evidently decreased compared to that in normal tissues, and low EPB41 expression was associated with poor prognoses for NSCLC patients. We further demonstrated the importance of EPB41 protein as a novel inhibitor of the Wnt signaling, which regulates ß-Catenin stability, and elucidated the crucial role of the EPB41/ALDOC/GSK3ß/ß-Catenin axis in NSCLC. Suppression of EPB41 expression in cancer cells elevated the levels of free ALDOC protein released from the EPB41-ALDOC complex, leading to disassembly of the ß-catenin destruction complex, reduced proteolytic degradation of ß-catenin, elevated cytoplasmic accumulation and nuclear translocation of ß-catenin, thereby activating the expression of multiple oncogenes and, thus, NSCLC pathogenesis. Our study highlights the potential of EPB41 as a future therapeutic target for lung cancer.

LncRNA SLC26A4-AS1 suppresses the MRN complex-mediated DNA repair signaling and thyroid cancer metastasis by destabilizing DDX5.

Lymph node metastasis is the major adverse feature for recurrence and death of thyroid cancer patients. To identify lncRNAs involved in thyroid cancer metastasis, we systemically screened differentially expressed lncRNAs in lymph node metastasis, thyroid cancer, and normal tissues via RNAseq. We found that lncRNA SLC26A4-AS1 was continuously, significantly down-regulated in normal tissues, thyroid cancer, and lymph node metastasis specimens. Low SLC26A4-AS1 levels in tissues were significantly associated with poor prognosis of thyroid cancer patients. LncRNA SLC26A4-AS1 markedly inhibited migration, invasion, and metastasis capability of cancer cells in vitro and in vivo. Intriguingly, SLC26A4-AS1 could simultaneously interact with DDX5 and the E3 ligase TRIM25, which promoting DDX5 degradation through the ubiquitin-proteasome pathway. In particular, SLC26A4-AS1 inhibited expression of multiple DNA double-strand breaks (DSBs) repair genes, especially genes coding proteins in the MRE11/RAS50/NBS1 (MRN) complex. Enhanced interaction between DDX5 and transcriptional factor E2F1 due to silencing of SLC26A4-AS1 promoted binding of the DDX5-E2F1 complex at promoters of the MRN genes and, thus, stimulate the MRN/ATM dependent DSB signaling and thyroid cancer metastasis. Our study uncovered new insights into the biology driving thyroid cancer metastasis and highlights potentials of lncRNAs as future therapeutic targets again cancer metastasis.

Starvation-induced suppression of DAZAP1 by miR-10b integrates splicing control into TSC2-regulated oncogenic autophagy in esophageal squamous cell carcinoma.

Esophageal squamous cell carcinoma (ESCC) accounts for about 90% of all incident esophageal cancers, with a 5-year survival rate of < 20%. Autophagy is of particular importance in cancers; however, the detailed regulatory mechanisms of oncogenic autophagy in ESCC have not been fully elucidated. In the present study, we address how splicing control of TSC2 is involved in mTOR-regulated oncogenic autophagy. Methods: Alternative splicing events controlled by DAZAP1 in ESCC cells were identified via RNAseq. Differential phosphorylation of short or long TSC2 splicing variants by AKT and their impacts on mTOR signaling were also examined. Results: We found that starvation-induced miR-10b could enhance autophagy via silencing DAZAP1, a key regulator of pre-mRNA alternative splicing. Intriguingly, we observed a large number of significantly changed alternative splicing events, especially exon skipping, upon RNAi of DAZAP1. TSC2 was verified as one of the crucial target genes of DAZAP1. Silencing of DAZAP1 led to the exclusion of TSC2 exon 26 (from Leu947 to Arg988), producing a short TSC2 isoform. The short TSC2 isoform cannot be phosphorylated at Ser981 by AKT, which resulted in continuous activation of TSC2 in ESCC. The active TSC2 inhibited mTOR via RHEB, leading to continually stimulated oncogenic autophagy of ESCC cells. Conclusions: Our data revealed an important physiological function of tumor suppressor DAZAP1 in autophagy regulation and highlighted the potential of controlling mRNA alternative splicing as an effective therapeutic application for cancers.

Silencing of lncRNA PVT1 by miR-214 inhibits the oncogenic GDF15 signaling and suppresses hepatocarcinogenesis.

The prognosis for hepatocellular carcinoma (HCC) is dismal. Long noncoding RNA PVT1 has been linked to malignancies and might be a deleterious therapy target. However, the key events controlling its expression in HCC remain undetermined. Here, we address how PVT1 is fine-regulated and its downstream signaling in hepatoma cells. Interestingly, we found that c-Myc and P53 could divergently regulate PVT1 transcription. Oncoprotein c-Myc enhances PVT1 expression, whereas P53 suppresses its expression. We also identified miR-214 as a crucial, negative regulator of PVT1. Consistently, high miR-214 levels were significantly correlated with diminished PVT1 expression in HCC specimens. Silencing of PVT1 by ectopic miR-214 or siRNAs markedly inhibited viability and invasion of HCC cells. In opposition, inhibition of endogenous miR-214 promoted PVT1 expression and enhanced cell proliferation. Notably, oncogenic GDF15 is a potential downstream target of the miR-214-PVT1 signaling. Collectively, our results show that the c-Myc/P53/miR-214-PVT1-GDF15 axis is implicated in HCC development, shedding light on the mechanistic actions of PVT1 and representing potential targets for HCC clinical intervention.

Functional BCL-2 rs2279115 Promoter Noncoding Variant Contributes to Glioma Predisposition, Especially in Males.

As a crucial oncogene, B cell lymphoma-2 (BCL-2) could promote cancer cell survival by inhibiting apoptosis via suppressing activation of proapoptotic proteins, such as BAX and BAK. There is a functional rs2279115 genetic polymorphism locating in BCL-2 promoter and deregulating BCL-2 expression. However, it is still largely undefined how BCL-2 rs2279115 promoter noncoding genetic variant is involved in glioma development. We examined the association between BCL-2 rs2279115 and glioma risk using a case-control approach. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by logistic regression adjusted by age and sex. Our results demonstrated that BCL-2 rs2279115 was significantly associated with glioma risk. The odd of individuals harboring A allele (CA + AA genotype) was 0.50 (95% CI = 0.39-0.64, p = 1.0 × 10-7) compared with CC genotype carriers. Stratification analyses by sex elucidated that BCL-2 rs2279115 was significantly associated with glioma risk in males (OR = 0.41, 95% CI = 0.30-0.58, p = 1.0 × 10-7), but not in females (p > 0.05). In summary, our results indicate that the functional BCL-2 rs2279115 genetic variant contributes to glioma predisposition and suggest prevalent involvement of regulatory genetic variations in glioma development.

LncRNA GAS5 Indel Genetic Polymorphism Contributes to Glioma Risk Through Interfering Binding of Transcriptional Factor TFAP2A.

Long noncoding RNA (lncRNA) growth arrest-specific 5 (GAS5) accumulates in growth-arrested cells and plays a crucial role in progression of multiple cancers, including glioma. There is a functional GAS5 rs145204276 indel genetic polymorphism in the promoter region. However, it is still largely unknown how the GAS5 indel genetic polymorphism is involved in etiology of glioma. We evaluated the association between the GAS5 indel genetic polymorphism and glioma development in a Chinese population. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by logistic regression adjusted by age and sex. We found that carriers of the GAS5 del allele was significantly associated with elevated risk of glioma (OR = 1.71, 95% CI = 1.34-2.18, p = 1.7 × 10-5). Compared with the GAS5 ins/ins genotype, the ins/del genotype or the del/del genotype was significantly associated with 1.57-fold or 2.61-fold increased glioma susceptibility (p = 0.001 or p = 9.0 × 10-6). When patients were stratified by disease subtypes, The GAS5 indel polymorphism was not significantly associated with risk of oligodendroglial tumor (p = 0.353). Integrated analyses indicated that the GAS5 indel polymorphism might alert the binding of transcriptional factor TFAP2A and activation of its expression based on ENCODE and REMBRANDT databases. Our results highlight the importance and potential of the biological relevance of the GAS5 indel genetic variant in glioma predisposition.

Clinical Implications of the BIM Deletion Polymorphism in Advanced Lung Adenocarcinoma Treated With Gefitinib.

BACKGROUND: Proapoptotic protein Bcl-2-like 11 (BIM) is a crucial tumor suppressor gene in lung cancer development. A 2903-bp genomic deletion polymorphism is present in BIM intron 2, which alters RNA splicing and impairs the generation of the death-inducing isoform of BIM and resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs). In the present study, we investigated the clinical implications of this genetic polymorphism in patients with advanced lung adenocarcinoma treated with gefitinib. MATERIALS AND METHODS: After genotyping the BIM deletion polymorphism in 111 patients with stage IIIB or IV lung adenocarcinoma receiving gefitinib, the hazard ratio (HR) and 95% confidence interval (CI) for progression-free survival and overall survival were estimated using Cox proportional hazards models. RESULTS: Possession of ≥ 1 deletion allele of the BIM polymorphism was observed in 18.02% of the patients. The BIM deletion polymorphism was an independent indicator of a shorter PFS (7.5 months vs. 11.3 months; HR, 2.38; 95% CI, 1.30-4.34; P = .005) and shorter OS (9.9 months vs. 27.5 months; HR, 2.53; 95% CI, 1.37-4.65; P = .003). Additionally, patients carrying the BIM deletion allele were more likely to experience acquired gefitinib-resistant disease. CONCLUSION: Our results indicate that the BIM deletion polymorphism might be a promising germline biomarker for gefitinib treatment in Chinese patients with lung adenocarcinoma.

LncRNA CDKN2BAS rs2157719 genetic variant contributes to medulloblastoma predisposition.

BACKGROUND: How germline single nucleotide polymorphisms are involved in the etiology of medulloblastoma remans poorly understood. We hypothesized that CCDKN2A/B rs1063192 and rs4977756 and also the long noncoding RNA (lncRNA) CDKN2BAS rs2157719 glioma susceptibility polymorphisms identified by genome-wide association studies may contribute to medulloblastoma predisposition. METHODS: To test this hypothesis, we genotyped these genetic variants among 160 medulloblastoma patients and 443 health controls in a Chinese population. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by logistic regression. RESULTS: We found that only the lncRNA CDKN2BAS rs2157719 T>C genetic polymorphism was significantly associated with an increased medulloblastoma risk (C allele: OR = 1.85, 95% CI = 1.32-2.58; p = 2.7 × 10-4 ). The stratified analyses showed an elevated risk of pediatric medulloblastoma associated with CDKN2BAS rs2157719 CC or TC genotype (both p < 0.05). Moreover, the association between the CDKN2BAS rs2157719 polymorphism and medulloblastoma risk is more pronounced in males (OR = 2.22, 95% CI = 1.36-3.62; p = 0.001). CONCLUSIONS: The findings of the present study provide important insights into the genetic complexities and predisposition of medulloblastoma in Chinese, especially at the lncRNA germline variation level.

Clinical Implications of the Autophagy Core Gene Variations in Advanced Lung Adenocarcinoma Treated with Gefitinib.

EGFR-TKIs show dramatic treatment benefits for advanced lung adenocarcinoma patients with activating EGFR mutations. Considering the essential role of autophagy in EGFR-TKIs treatments, we hypothesized that genetic variants in autophagy core genes might contribute to outcomes of advanced lung adenocarcinoma treated with gefitinib. We systematically examined 27 potentially functional genetic polymorphisms in 11 autophagy core genes among 108 gefitinib-treated advanced lung adenocarcinoma patients. We found that ATG10 rs10036653, ATG12 rs26538, ATG16L1 rs2241880 and ATG16L2 rs11235604 were significantly associated with survival of lung adenocarcinoma patients (all P < 0.05). Among EGFR-mutant patients, ATG5 rs688810, ATG5 rs510432, ATG7 rs8154, ATG10 rs10036653, ATG12 rs26538, ATG16L1 rs2241880 and ATG16L2 rs11235604 significantly contributed to disease prognosis. We also found that ATG5 rs510432, ATG5 rs688810, ATG10 rs10036653 and ATG10 rs1864182 were associated with primary or acquired resistance to gefitinib. Functional analyses of ATG10 rs10036653 polymorphism suggested that ATG10 A allele might increase transcription factor OCT4 binding affinity compared to the T allele in lung cancer cells. Our results indicate that autophagy core genetic variants show potential clinical implications in gefitinib treatment, especially among advanced lung adenocarcinoma patients, highlighting the possibility of patient-tailored decisions during EGFR-TKIs based on both germline and somatic variation detection.

CHST9 rs1436904 genetic variant contributes to prognosis of triple-negative breast cancer.

Triple-negative breast cancer (TNBC) refers to one aggressive histological subtype of breast cancer with high heterogeneity and poor prognosis after standard therapy. Lack of clearly established molecular mechanism driving TNBC progression makes personalized therapy more difficult. Thus, identification of genetic variants associated with TNBC prognosis will show clinic significance for individualized treatments. Our study is aimed to evaluate the prognostic value of the genome wide association study (GWAS)-identified CHST9 rs1436904 and AQP4 rs527616 genetic variants in our established early-stage TNBC sample database. Cox regression was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). CHST9 rs1436904G allele was significantly associated with decreased disease-free survival time (DFS) (8.5 months shorter in GG genotype carriers compared to TT genotype carriers, HR = 1.70, 95% CI = 1.03-2.81, P = 0.038). Stratified analyses showed an increased risk of cancer progression in CHST9 rs1436904G allele carriers harboring larger tumor (tumor size > 2 cm), without lymph-node metastasis, being premenopausal at diagnosis or with vascular invasion (P = 0.032, 0.017, 0.008 or 0.003). Our findings demonstrate that the GWAS-identified 18q11.2 CHST9 rs1436904 polymorphism significantly contributes to prognosis of early-stage TNBC, suggesting its clinical potential in the screening of high-risk TNBC patients for recurrence and the possibility of patient-tailored therapeutic decisions.

The long noncoding RNA PCAT-1 links the microRNA miR-215 to oncogene CRKL-mediated signaling in hepatocellular carcinoma.

The long non-coding RNA (lncRNA) PCAT-1 resides in the chromosome 8q24 cancer-risk locus and acts as a vital oncogene during tumorigenesis and progression. However, how PCAT-1 is post-transcriptionally regulated, for example, by small ncRNAs, such as microRNAs (miRNAs) is largely unknown. Here, we report how miRNAs regulate PCAT-1 expression and also investigate the biological significance of this regulation in hepatocellular carcinoma (HCC). We found that miR-215, a P53-inducible miRNA, is a key regulator of PCAT-1 expression in HCC and identified an interaction between miR-215 and PCAT-1 in dual luciferase reporter gene assays. We also found that post-transcriptional silencing of PCAT-1 by miR-215 or PCAT-1 siRNAs significantly inhibited proliferation of HCC cells and, conversely, that inhibition of endogenous miR-215 up-regulated PCAT-1 expression and promoted cell viability. The tumor-suppressing role of miR-215 was further confirmed in an in vivo mouse HCC xenograft model. Of note, gene profiling assays suggested that the kinase CRK-like proto-oncogene, adaptor protein (CRKL), is a potential downstream target of the miR-215-PCAT-1 axis in HCC, and we demonstrated that CRKL silencing significantly suppresses cell proliferation. Taken together and considering the essential role of CRKL in cancer cells, we propose that the TP53-miR-215-PCAT-1-CRKL axis might represent an important regulatory pathway in HCC. In summary, our results highlight the involvement of several ncRNAs in HCC and thus provide critical insights into the molecular pathways operating in this malignancy.

Expressions of CD8+TILs, PD-L1 and Foxp3+TILs in stage I NSCLC guiding adjuvant chemotherapy decisions.

PURPOSE: Currently, adjuvant chemotherapy is recommended for patients with high risk stage I non-small cell lung cancer (NSCLC). However, identifying high risk patients remains a challenge. This study aims to identify the patient cohorts more likely to benefit from adjuvant chemotherapy based on the tumor micro-immune environment. RESULTS: CD8+TILs significantly associated with disease-free survival (DFS) and overall survial (OS) (p=0.002; 0.040). Patients with high risk factors may also predict shorter DFS (P=0.056). When compared together, patients with high-CD8+TILs showed better DFS than patients with low-CD8+TILs, no matter their risk factors status. There's no correlation between PD-L1 expressions and survival. PD-L1 was highly expressed in men, squamous and well differentiated carcinoma. In addition, Foxp3+TILs alone didn't show any prognostic effects, but low-Foxp3/high-CD8+TILs were associated with prolonged DFS (p=0.031). METHODS: A total of 126 patients with surgically resected stage I NSCLC were included to perform immunohistochemistry of CD8+ tumor infiltrating lymphocytes (TILs), programmed death ligand-1(PD-L1) and forkhead box P3 (Foxp3)+TILs. CONCLUSION: CD8+TILs are effective prognostic predictors. Patients with surgically resected stage I NSCLC showing low CD8+TILs could be considered for adjuvant chemotherapy, even if they have no high risk features.

The CUL4B/AKT/ß-Catenin Axis Restricts the Accumulation of Myeloid-Derived Suppressor Cells to Prohibit the Establishment of a Tumor-Permissive Microenvironment.

Cancer progression requires a permissive microenvironment that shields cancer from the host immunosurveillance. The presence of myeloid-derived suppressor cells (MDSC) is a key feature of a tumor-permissive microenvironment. Cullin 4B (CUL4B), a scaffold protein in the Cullin 4B-RING E3 ligase complex (CRL4B), represses tumor suppressors through diverse epigenetic mechanisms and is overexpressed in many malignancies. We report here that CUL4B unexpectedly functions as a negative regulator of MDSC functions in multiple tumor settings. Conditional ablation of CUL4B in the hematopoietic system, driven by Tek-Cre, resulted in significantly enhanced accumulation and activity of MDSCs. Mechanistically, we demonstrate that the aberrant abundance of MDSCs in the absence of CUL4B was mediated by the downregulation of the AKT/ß-catenin pathway. Moreover, CUL4B repressed the phosphatases PP2A and PHLPP1/2 that dephosphorylate and inactivate AKT to sustain pathway activation. Importantly, the CUL4B/AKT/ß-catenin axis was downregulated in MDSCs of healthy individuals and was further suppressed in tumor-bearing mice and cancer patients. Thus, our findings point to a pro- and antitumorigenic role for CUL4B in malignancy, in which its ability to impede the formation of a tumor-supportive microenvironment may be context-specific.

Lack of CUL4B leads to increased abundance of GFAP-positive cells that is mediated by PTGDS in mouse brain.

Astrocytes are the most abundant cell type in the mammalian brain and are important for the functions of the central nervous system. Glial fibrillary acidic protein (GFAP) is regarded as a hallmark of mature astrocytes, though some GFPA-positive cells may act as neural stem cells. Missense heterozygous mutations in GFAP cause Alexander disease that manifests leukodystrophy and intellectual disability. Here, we show that CUL4B, a scaffold protein that assembles E3 ubiquitin ligase, represses the expression of GFAP in neural progenitor cells (NPCs) during brain development. Lack of Cul4b in NPCs in cultures led to increased generation of astrocytes, marked by GFAP and S100ß. The GFAP+ cells were also found to be more abundant in the brains of nervous system-specific Cul4b knockout mice in vivo. Moreover, we demonstrated that the increased generation of GFAP+ cells from Cul4b-null NPCs was mediated by an upregulation of prostaglandin D2 synthase PTGDS. We showed that the increased GFAP expression can be attenuated by pharmacological inhibition of the PTGDS enzymatic activity or by shRNA-mediated knockdown of Ptgds. Importantly, exogenously added PTGDS could promote the generation of GFAP+ cells from wild-type NPCs. We further observed that Ptgds is targeted and repressed by the CUL4B/PRC2 complex. Together, our results demonstrate CUL4B as a negative regulator of GFAP expression during neural development.

Accelerated hepatocellular carcinoma development in CUL4B transgenic mice.

Cullin 4B (CUL4B) is a component of the Cullin 4B-Ring E3 ligase (CRL4B) complex that functions in proteolysis and in epigenetic regulation. CUL4B possesses tumor-promoting properties and is markedly upregulated in many types of human cancers. To determine the role of CUL4B in liver tumorigenesis, we generated transgenic mice that expressed human CUL4B in livers and other tissues and evaluated the development of spontaneous and chemically-induced hepatocellular carcinomas. We observed that CUL4B transgenic mice spontaneously developed liver tumors at a high incidence at old ages and exhibited enhanced DEN-induced hepatocarcinogenesis. There was a high proliferation rate in the livers of CUL4B transgenic mice that was accompanied by increased levels of Cdk1, Cdk4 and cyclin D1 and decreased level of p16. The transgenic mice also exhibited increased compensatory proliferation after DEN-induced liver injury, which was accompanied by activation of Akt, Erk, p38 and NF-κB. We also found that Prdx3 was downregulated and that DEN induced a higher level of reactive oxygen species in the livers of transgenic mice. Together, our results demonstrate a critical role of CUL4B in hepatocarcinogenesis in mice.

miR-155 Deficiency Ameliorates Autoimmune Inflammation of Systemic Lupus Erythematosus by Targeting S1pr1 in Faslpr/lpr Mice.

MicroRNA-155 (miR-155) was previously found involved in the development of systemic lupus erythematosus (SLE) and other autoimmune diseases and the inflammatory response; however, the detailed mechanism of miR-155 in SLE is not fully understood. To explore the in vivo role of miR-155 in the pathogenesis of SLE, miR-155-deficient Fas(lpr/lpr) (miR-155(-/-)Fas(lpr/lpr)) mice were obtained by crossing miR-155(-/-) and Fas(lpr/lpr) mice. Clinical SLE features such as glomerulonephritis, autoantibody levels, and immune system cell populations were compared between miR-155(-/-)Fas(lpr/lpr) and Fas(lpr/lpr) mice. Microarray analysis, RT-PCR, Western blot, and luciferase reporter gene assay were used to identify the target gene of miR-155. miR-155(-/-)Fas(lpr/lpr) mice showed milder SLE clinical features than did Fas(lpr/lpr)mice. As compared with Fas(lpr/lpr) mice, miR-155(-/-)Fas(lpr/lpr) mice showed less deposition of total IgA, IgM, and IgG and less infiltration of inflammatory cells in the kidney. Moreover, the serum levels of IL-4 and IL-17a, secreted by Th2 and Th17 cells, were lower in miR-155(-/-)Fas(lpr/lpr) than Fas(lpr/lpr) mice; the CD4(+)/CD8(+) T cell ratio was restored in miR-155(-/-)Fas(lpr/lpr) mice as well. Sphingosine-1-phosphate receptor 1 (S1PR1) was found as a new target gene of miR-155 by in vitro and in vivo studies; its expression was decreased in SLE patients and Fas(lpr/lpr) mice. miR-155(-/-)Fas(lpr/lpr) mice are resistant to the development of SLE by the regulation of the target gene S1pr1. miR-155 might be a new target for therapeutic intervention in SLE.

CUL4B activates Wnt/ß-catenin signalling in hepatocellular carcinoma by repressing Wnt antagonists.

Activation of Wnt/ß-catenin signalling is frequently observed in many types of cancer including hepatocellular carcinoma (HCC). We recently reported that cullin 4B (CUL4B), a scaffold protein that assembles CRL4B ubiquitin ligase complexes, is overexpressed in many types of solid tumours and contributes to epigenetic silencing of tumour suppressors. In this study, we characterized the function of CUL4B in HCC and investigated whether CUL4B is involved in the regulation of Wnt/ß-catenin signalling. CUL4B and ß-catenin were frequently up-regulated and positively correlated in HCC tissues. CUL4B activated Wnt/ß-catenin signalling by protecting ß-catenin from GSK3-mediated degradation, achieved through CUL4B-mediated epigenetic silencing of Wnt pathway antagonists. Knockdown of CUL4B resulted in the up-regulation of Wnt signal antagonists such as DKK1 and PPP2R2B. Simultaneous knockdown of PPP2R2B partially reversed the down-regulation of ß-catenin signalling caused by CUL4B depletion. Furthermore, CRL4B promoted the recruitment and/or retention of PRC2 at the promoters of Wnt antagonists and CUL4B knockdown decreased the retention of PRC2 components as well as H3K27me3. Knockdown of CUL4B reduced the proliferation, colony formation, and invasiveness of HCC cells in vitro and inhibited tumour growth in vivo, and these effects were attenuated by introduction of exogenous ß-catenin or simultaneous knockdown of PPP2R2B. Conversely, ectopic expression of CUL4B enhanced the proliferation and invasiveness of HCC cells. We conclude that CUL4B can up-regulate Wnt/ß-catenin signalling in human HCC through transcriptionally repressing Wnt antagonists and thus contributes to the malignancy of HCC.