TPD52L2 impacts proliferation, invasiveness and apoptosis of glioblastoma cells via modulation of wnt/β-catenin/snail signaling

Identification of Key MicroRNAs and Genes between Colorectal Adenoma and Colorectal Cancer via Deep Learning on GEO Databases and Bioinformatics

Background

Deep learning techniques are gaining momentum in medical research. Colorectal adenoma (CRA) is a precancerous lesion that may develop into colorectal cancer (CRC) and its etiology and pathogenesis are unclear. This study aims to identify transcriptome differences between CRA and CRC via deep learning on Gene Expression Omnibus (GEO) databases and bioinformatics in the Chinese population.

Methods

In this study, three microarray datasets from the GEO database were used to identify the differentially expressed genes (DEGs) and differentially expressed miRNAs (DEMs) in CRA and CRC. The FunRich software was performed to predict the targeted mRNAs of DEMs. The targeted mRNAs were overlapped with DEGs to determine the key DEGs. Molecular mechanisms of CRA and CRC were evaluated using enrichment analysis. Cytoscape was used to construct protein-protein interaction (PPI) and miRNA-mRNA regulatory networks. We analyzed the expression of key DEMs and DEGs, their prognosis, and correlation with immune infiltration based on the Kaplan-Meier plotter, UALCAN, and TIMER databases.

Results

A total of 38 DEGs are obtained after the intersection, including 11 upregulated genes and 27 downregulated genes. The DEGs were involved in the pathways, including epithelial-to-mesenchymal transition, sphingolipid metabolism, and intrinsic pathway for apoptosis. The expression of has-miR-34c (P = 0.036), hsa-miR-320a (P = 0.045), and has-miR-338 (P = 0.0063) was correlated with the prognosis of CRC patients. The expression levels of BCL2, PPM1L, ARHGAP44, and PRKACB in CRC tissues were significantly lower than normal tissues (P < 0.001), while the expression levels of TPD52L2 and WNK4 in CRC tissues were significantly higher than normal tissues (P < 0.01). These key genes are significantly associated with the immune infiltration of CRC.

Conclusion

This preliminary study will help identify patients with CRA and early CRC and establish prevention and monitoring strategies to reduce the incidence of CRC.

SMARCC2 mediates the regulation of DKK1 by the transcription factor EGR1 through chromatin remodeling to reduce the proliferative capacity of glioblastoma

Switch/sucrose-nonfermenting (SWI/SNF) complexes play a key role in chromatin remodeling. Recent studies have found that SMARCC2, as the core subunit of the fundamental module of the complex, plays a key role in its early assembly. In this study, we found a unique function of SMARCC2 in inhibiting the progression of glioblastoma by targeting the DKK1 signaling axis. Low expression of SMARCC2 is found in malignant glioblastoma (GBM) compared with low-grade gliomas. SMARCC2 knockout promoted the proliferation of glioblastoma cells, while its overexpression showed the opposite effect. Mechanistically, SMARCC2 negatively regulates transcription by dynamically regulating the chromatin structure and closing the promoter region of the target gene DKK1, which can be bound by the transcription factor EGR1. DKK1 knockdown significantly reduced the proliferation of glioblastoma cell lines by inhibiting the PI3K-AKT pathway. We also studied the functions of the SWIRM and SANT domains of SMARCC2 and found that the SWIRM domain plays a more important role in the complete chromatin remodeling function of SMARCC2. In addition, in vivo studies confirmed that overexpression of SMARCC2 could significantly inhibit the size of intracranial gliomas in situ in nude mice. Overall, this study shows that SMARCC2, as a tumor suppressor, inhibits the proliferation of glioblastoma by targeting the transcription of the oncogene DKK1 through chromatin remodeling, indicating that SMARCC2 is a potentially attractive therapeutic target in glioblastoma.

Investigation of Transcript Variant 6 of TPD52L2 as a Prognostic and Predictive Biomarker in Basal-Like MDA-MB-231 and MDA-MB-453 Cell Lines for Breast Cancer

Background

Basal-like breast cancer (BLBC) exhibits worse pathological features than other breast cancer subtypes, and patients diagnosed with BLBC have short disease-free and overall survival times. Thus, the identification of novel biomarkers and therapeutic targets for BLBC is of upmost importance. Although TPD52L2 is upregulated in multiple cancers, little is known about its roles in BLBC.

Methods

RNA levels were analyzed between breast cancer tissues and paired adjacent normal tissues using RNA-seq data from The Cancer Genome Atlas (TCGA). TPD52L2 stable knockdown and inducible knockout cell lines were established using basal-like MDA-MB-231 and MDA-MB-453 cell lines. Cell proliferation assays in vitro and tumor growth analysis in vivo were performed to determine the function of TPD52L2 during BLBC progression. Transwell assays were used to estimate the regulatory effect of TPD52L2 on BLBC cell migration. The expression profile of all tpd52l2 transcripts was analyzed to assess the functional protein isoform. Association of transcript variant 6 (V6) expression with pathological parameters was carried out using the clinical data of the BRCA cohort.

Results

We identified V6 of TPD52L2 as a novel biomarker and regulator of BLBC progression. TPD52L2 is upregulated in BLBCs and associated with patient outcomes. TPD52L2 knockdown suppresses tumor growth, and V6 correlates with cancer-related phenotypes in BLBC. Clinical data further proved that V6 is associated with different pathological features, such as pathological stage and pathological tumor status, and independently predicts patient outcomes and responses to therapies.

Conclusions

Our findings demonstrate that V6 of TPD52L2 is a novel biomarker for BLBC patients. V6 promotes cell proliferation and migration and has marked oncogenic roles in determining the malignant phenotypes of BLBC.

The Antitumor Effect of TPD52L2 Silencing on Oxaliplatin-Resistant Gastric Carcinoma Is Related to Endoplasmic Reticulum Stress In Vitro

Tumor protein D52-like 2 or simply TPD52L2 belongs to the TPD52 family which has been implicated in a variety of human carcinomas. However, the TPD52L2 function in the gastric carcinoma oxaliplatin (OXA) resistance remains elusive. The main objective of this study is to evaluate the TPD52L2 effect in OXA-resistant gastric carcinoma cells in vitro. Oxaliplatin-resistant gastric carcinoma cells were generated in MGC-803 and SGC-7901 cells. siRNA-mediated knockdown of TPD52L2 was investigated in OXA-resistant MGC-803-OXA and SGC-7901-OXA cells. qRT-PCR was performed to assess the expression level of TPD52L2 mRNA. TPD52L2 protein expression level, apoptosis, and endoplasmic reticulum (ER) stress-associated proteins were identified via immunoblotting analysis. MTT assay was conducted for the evaluation of cell viability, while colony-forming activity was carried out via crystal violet staining. SGC-7901-OXA and MGC-803-OXA cells were found to be more resistant to OXA, as compared to the parental cell lines. The expression of TPD52L2 was found to be upregulated in OXA-resistant cells. Knockdown of TPD52L2 suppressed cell colony-forming potency, cell growth, and development in OXA-resistant cells. TPD52L2 knockdown also enhanced the PARP and caspase-3 cleavage. ER-associated proteins such as PERK, GRP78, CHOP, and IRE1α were found to be elevated in TPD52L2 knockdown cells. ER stress might be involved in TPD52L2 knockdown-induced apoptosis in OXA-resistant gastric carcinoma cells.

TPD52L2 Is a Prognostic Biomarker and Correlated With Immune Infiltration in Lung Adenocarcinoma

Tumor protein D52-like 2 (TPD52L2) belongs to the members of the TPD52 family. TPD52L2 was reported to regulate proliferation and apoptosis in cancer cells. However, its role in lung adenocarcinoma (LUAD) was uncertain. We evaluated the expression, methylation, copy number alteration, and prognostic significance of TPD52L2 using RNA-seq data from The Cancer Genome Atlas (TCGA). Enrichment analysis of TPD52L2 was conducted using the R package “clusterProfiler.” We further assessed the association between TPD52L2 and immune cell infiltration level, immunosuppressive genes, and tumor mutational burden (TMB). The difference of gene mutant frequency in high- and low-TPD52L2 groups was also analyzed. The results showed that TPD52L2 was over-expressed and predicted worse survival status in LUAD. We also found that TPD52L2 expression was positively associated with the infiltration levels of immunosuppressive cells, such as regulatory T cells (Tregs) and tumor-associated macrophages (TAMs), and negatively correlated with immune killer cells, such as CD8⁺ T and NK cells in pan-cancer, including LUAD. In addition, TPD52L2 expression was associated with immunosuppressive genes and TMB. High expression of TPD52L2 was with more mutant frequency of TP53. In summary, our results show that TPD52L2 is an oncogene and a potential prognostic biomarker in LUAD. High TPD52L2 expression is a possible indicator of immune infiltration and associated with tumor immunosuppressive status in LUAD.

Overview of the molecular mechanisms of migration and invasion in glioblastoma multiforme

Glioblastoma (GBM) is one of the most devastating cancers, with an approximate median survival of only 16 months. Although some new insights into the fantastic heterogeneity of this kind of brain tumor have been revealed in recent studies, all subclasses of GBM still demonstrate highly aggressive invasion properties to the surrounding parenchyma. This behavior has become the main obstruction to current curative therapies as invasive GBM cells migrate away from these foci after surgical therapies. Therefore, this review aimed to provide a relatively comprehensive study of GBM invasion mechanisms, which contains an intricate network of interactions and signaling pathways with the extracellular matrix (ECM). Among these related molecules, TGF-β, the ECM, Akt, and microRNAs are most significant in terms of cellular procedures related to GBM motility and invasion. Moreover, we also review data indicating that Musashi-1 (MSI1), a neural RNA-binding protein (RBP), regulates GBM motility and invasion, maintains stem cell populations in GBM, and promotes drug-resistant GBM phenotypes by stimulating necessary oncogenic signaling pathways through binding and regulating mRNA stability. Importantly, these necessary oncogenic signaling pathways have a close connection with TGF-β, ECM, and Akt. Thus, it appears promising to find MSI-specific inhibitors or RNA interference-based treatments to prevent the actions of these molecules despite using RBPs, which are known as hard therapeutic targets. In summary, this review aims to provide a better understanding of these signaling pathways to help in developing novel therapeutic approaches with better outcomes in preclinical studies.

SMARCC2 combined with c‑Myc inhibits the migration and invasion of glioma cells via modulation of the Wnt/β‑catenin signaling pathway

Glioma is the most common type of central nervous system tumor. SWItch/sucrose non-fermentable (SWI/SNF) is a tumor suppressor that serves an important role in epithelial-mesenchymal transition (EMT). The present study aimed to identify key molecules involved in the EMT process. SWI/SNF related, matrix associated, actin dependent regulator of chromatin subfamily c member 2 (SMARCC2) is mutated in and its expression is low in multiple types of cancer. SMARCC2 is the core subunit of the chromatin-remodeling complex, SWI/SNF. Relative mRNA SMARCC2 expression levels in human glioma tissue were analyzed via reverse transcription-quantitative PCR, whereas the protein expression levels were determined via immunohistochemistry staining. SMARCC2 expression was knocked down in glioma cells using small interfering RNA (si) and overexpressed by infection with adenovirus vectors carrying SMARCC2 cDNA. Wound healing and Transwell assays were performed to assess cell migration and invasion, respectively. Subsequently, immunofluorescence and western blotting were performed to analyze the expression levels of the oncogene c-Myc, which is associated with SMARCC2. SMARCC2 combines with C-MYC to downregulate its expression. Consistent with the results of the bioinformatics analysis, which revealed that the upregulated expression levels of SMARCC2 were associated with a more favorable prognosis in patients with glioma, the mRNA and protein expression levels of SMARCC2 were significantly upregulated in low-grade glioma tissues compared with high-grade glioma tissues. The results of the wound healing assay demonstrated that cell migration was significantly increased in the siSMARCC2-1/3 groups compared with the negative control (NC) group. By contrast, the migratory ability of cells was significantly reduced following transduction with adenovirus overexpressing SMARCC2, which upregulated the expression of SMARCC2, compared with the lentiviral vector-non-specific control (LVS-NC) group. The Transwell assay results further showed that SMARCC2 overexpression significantly inhibited the migratory and invasive abilities of U87MG and LN229 cells compared with the LVS-NC group. Co-immunoprecipitation assays were subsequently conducted to validate the binding of SMARCC2 and c-Myc; the results demonstrated that the expression of c-Myc was downregulated in adenovirus-transfected cells compared with LVS-NC-transfected cells. The results of the western blotting experiments demonstrated that the expression levels of N-cadherin, vimentin, snail family transcriptional repressor 1 and β-catenin were notably downregulated, whereas the expression levels of T-cadherin were markedly upregulated in cell lines stably overexpressing SMARCC2 compared with the LVS-NC group. In conclusion, the results of the present study suggested that SMARCC2 may inhibit Wnt/β-catenin signaling by regulating c-Myc expression in glioma. SMARCC2 regulates the EMT status of the glioblastoma cell line by mediating the expression of the oncogene C-MYC to inhibit its migration and invasion ability. Thus, SMARCC2 may function as a tumor suppressor or oncogene by regulating associated oncogenes or tumor suppressor genes.

FOXM1/DVL2/Snail axis drives metastasis and chemoresistance of colorectal cancer

Colorectal cancer (CRC) is the third most common type of cancer worldwide. Metastasis and chemoresistance are regarded as the two leading causes of treatment failure and high mortality in CRC. Forkhead Box M1 (FOXM1) has been involved in malignant behaviors of cancer. However, the role and mechanism of FOXM1 in simultaneously regulating metastasis and chemoresistance of CRC remain poorly understood. Here, we found that FOXM1 was overexpressed in oxaliplatin- and vincristine-resistant CRC cells (HCT-8/L-OHP and HCT-8/VCR) with enhanced metastatic potential, compared with HCT-8 cells. FOXM1 overexpression increased migration, invasion and drug-resistance to oxaliplatin and vincristine in HCT-8 cells, while FOXM1 knockdown using shFOXM1 impaired metastasis and drug-resistance in HCT-8/L-OHP and HCT-8/VCR cells. Moreover, FOXM1 up-regulated Snail to trigger epithelial-mesenchymal transition-like molecular changes and multidrug-resistance protein P-gp expression, while silencing Snail inhibited FOXM1-induced metastasis and drug-resistance. We further identified that disheveled-2 (DVL2) was crucial for FOXM1-induced Snail expression, metastasis and chemoresistance. Furthermore, FOXM1 bound to DVL2, and enhanced nuclear translocation of DVL2 and DVL2-mediated transcriptional activity of Wnt/β-catenin known to induce Snail expression. In conclusion, FOXM1/DVL2/Snail axis triggered aggressiveness of CRC. Blocking FOXM1/DVL2/Snail pathway simultaneously inhibited metastasis and chemoresistance in CRC cells, providing a new strategy for successful CRC treatment.

A reproduceable in situ xenograft model of spinal glioma

BACKGROUND

Spinal glioma is a nervous system tumor that tends to relapse and has no specific prognostic molecular biomarkers. Thus, a stable and reproduceable animal research model of spinal glioma is urgently needed.

NEW METHOD

We established a new in situ tumor xenograft model of spinal glioma using nude mice. In this study, we implanted tumors into the cervical spinal cord of nude mice to mimic the pathological characteristics of the original tumors.

RESULTS

Through anatomical experiments, we found that the cervical lamina of mice was thinner, the intervertebral space was much wider, and the adhesion muscles were more easily separated. According to the examination of spinal cord sections, the best puncture point we identified was located 0.9 mm lateral to the posterior median line at the level of the line between the midpoints of the scapulae and at a depth of 0.9 mm. In the nude mouse xenograft experiment, the implanted tumor tissue retained the pathological characteristics of the original tumor.

COMPARISON WITH EXISTING METHOD(S)

This model used the cervical spinal cord as the puncture site and patient-derived primary tumor cells, which has never been performed before. Tumor cells could be injected directly without damaging the lamina. Thus, we could reduce the risk of man-made spinal cord injury and infection and avoid destroying the stability and integrity of the spine.

CONCLUSIONS

This study established a stable and reliable animal model of spinal glioma for further molecular research and targeted therapy development.

Wnt/beta-catenin and PI3K/Akt/mTOR Signaling Pathways in Glioblastoma: Two Main Targets for Drug Design: A Review

Glioblastoma (GBM) is the most common and malignant astrocytic glioma, accounting for about 90% of all brain tumors with poor prognosis. Despite recent advances in understanding molecular mechanisms of oncogenesis and the improved neuroimaging technologies, surgery, and adjuvant treatments, the clinical prognosis of patients with GBM remains persistently unfavorable. The signaling pathways and the regulation of growth factors of glioblastoma cells are very abnormal. The various signaling pathways have been suggested to be involved in cellular proliferation, invasion, and glioma metastasis. The Wnt signaling pathway with its pleiotropic functions in neurogenesis and stem cell proliferation is implicated in various human cancers, including glioma. In addition, the PI3K/Akt/mTOR pathway is closely related to growth, metabolism, survival, angiogenesis, autophagy, and chemotherapy resistance of GBM. Understanding the mechanisms of GBM's invasion, represented by invasion and migration, is an important tool in designing effective therapeutic interventions. This review will investigate two main signaling pathways in GBM: PI3K/Akt/mTOR and Wnt/beta-catenin signaling pathways.

Variant-to-Gene-Mapping Analyses Reveal a Role for the Hypothalamus in Genetic Susceptibility to Inflammatory Bowel Disease

BACKGROUND & AIMS

Inflammatory bowel disease (IBD) is a polygenic disorder characterized principally by dysregulated inflammation impacting the gastrointestinal tract. However, there also is increasing evidence for a clinical association with stress and depression. Given the role of the hypothalamus in stress responses and in the pathogenesis of depression, useful insights could be gleaned from understanding its genetic role in IBD.

METHODS

We conducted genetic correlation analyses on publicly available genome-wide association study summary statistics for depression and IBD traits to identify genetic commonalities. We used partitioned linkage disequilibrium score regression, leveraging our ATAC sequencing and promoter-focused Capture C data, to measure enrichment of IBD single-nucleotide polymorphisms within promoter-interacting open chromatin regions of human embryonic stem cell-derived hypothalamic-like neurons (HNs). Using the same data sets, we performed variant-to-gene mapping to implicate putative IBD effector genes in HNs. To contrast these results, we similarly analyzed 3-dimensional genomic data generated in epithelium-derived colonoids from rectal biopsy specimens from donors without pathologic disease noted at the time of colonoscopy. Finally, we conducted enrichment pathway analyses on the implicated genes to identify putative IBD dysfunctional pathways.

RESULTS

We found significant genetic correlations (rg) of 0.122 with an adjusted P (Padj) = 1.4 × 10-4 for IBD: rg = 0.122; Padj = 2.5 × 10-3 for ulcerative colitis and genetic correlation (rg) = 0.094; Padj = 2.5 × 10-3 for Crohn's disease, and significant approximately 4-fold (P = .005) and approximately 7-fold (P = .03) enrichment of IBD single-nucleotide polymorphisms in HNs and colonoids, respectively. We implicated 25 associated genes in HNs, among which CREM, CNTF, and RHOA encode key regulators of stress. Seven genes also additionally were implicated in the colonoids. We observed an overall enrichment for immune and hormonal signaling pathways, and a colonoid-specific enrichment for microbiota-relevant terms.

CONCLUSIONS

Our results suggest that the hypothalamus warrants further study in the context of IBD pathogenesis.

Comprehensive analysis of location-specific hub genes related to the pathogenesis of colon cancer

The molecular mechanisms underlying colon cancer lesions at different sites are not entirely clear. Herein, we aimed to explore location-specific gene profiles related to the pathogenesis of colon cancer and to identify their function. The robust rank aggregation (RRA) method was used to integrate colon cancer microarray datasets and screen differentially expressed gene (DEG) profiles between left- and right-sided colon cancers. Then, weighted gene co-expression network analysis (WGCNA) was performed to cluster the DEGs into modules and identify hub genes. The selected hub genes were validated using The Cancer Genome Atlas dataset and clinical tissues. We assessed the association of selected hub genes with the methylation status in immune cells. In total, 905 DEGs were identified by RRA; five gene modules and 18 hub genes were related to the clinical traits of colon cancer by WGCNA. Four hub genes were selected and shown to be associated with colon cancers on different sides and distant metastasis in the validation analysis. The four hub genes showed a low methylation status, and their expression was significantly associated with methylation status. Positive correlations were observed between the four hub genes and tumor purity and among the four types of immune cells. Gene set enrichment analysis revealed that the four hub genes were mainly involved in two cancer-related pathways. In conclusion, this study identified a set of location-specific genes related to the pathogenesis of colon cancer. These four hub genes may act as novel candidate targets for the treatment of colon cancer.

Combination Therapy with Nanomicellar-Curcumin and Temozolomide for In Vitro Therapy of Glioblastoma Multiforme via Wnt Signaling Pathways

Glioblastoma (GBM) is the most serious brain tumor and shows a high rate of drug resistance. Wnt signaling is a very important pathway in GBM that can activate/inhibit other pathways, such as apoptosis and autophagy. In this study, we evaluated the efficacy of a combination of temozolomide (TMZ) plus curcumin or nanomicellar-curcumin on the inhibition of GBM growth in vitro, via effects on autophagy, apoptosis, and the Wnt signaling pathway. Two concentrations of curcumin and nanomicellar-curcumin (i.e., 20 μM and 50 μM) alone, and in combination with TMZ (50 μM) were used to induce cytotoxicity in the U87 GBM cell line. Wnt signaling-, autophagy-, and apoptosis-related genes were assessed by quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) and Western blots. All treatments (except 20 μM curcumin alone) significantly decreased the viability of U87 cells compared to controls. Curcumin (50 μM), nanomicellar-curcumin alone and in combination with TMZ significantly decreased the invasion and migration of U87 cells. Autophagy-related proteins (Beclin 1, LC3-I, LC3-II) were significantly increased. Apoptosis-related proteins (Bcl-2 and caspase 8) were also significantly increased, while Bax protein was significantly decreased. The expression levels of Wnt pathway-associated genes (β-catenin, cyclin D1, Twist, and ZEB1) were significantly reduced.

Triptolide inhibits epithelial‑mesenchymal transition and induces apoptosis in gefitinib‑resistant lung cancer cells

The epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI), gefitinib, is used widely to treat non-small cell lung cancer (NSCLC) with EGFR-activating mutations. Unfortunately, the acquired drug resistance promoted by epithelial-mesenchymal transition (EMT) markedly limits the clinical effects and remains a major barrier to a cure. Our previous isobaric tags for relative and absolute quantitation-based proteomics analysis revealed that the E-cadherin protein level was markedly upregulated by triptolide (TP). The present study aimed to determine whether TP reverses the gefitinib resistance of human lung cancer cells by regulating EMT. It was revealed that TP combined with gefitinib synergistically inhibited the migration and invasion of lung adenocarcinoma cell line A549; the combination treatment had a significantly better outcome than that of TP and gefitinib alone. Moreover, TP effectively increased the sensitivity of drug resistant A549 cells to gefitinib by upregulating E-cadherin protein expression and downregulating the MMP9, SNAIL, and vimentin expression levels. The dysregulated E-cadherin expression of gefitinib-sensitive cells induced gefitinib resistance, which could be overcome by TP. Finally, TP combined with gefitinib significantly inhibited the growth of xenograft tumors induced using gefitinib-resistant A549 cells, which was associated with EMT reversal and E-cadherin signaling activation in vivo. The present results indicated that the combination of TP and TKIs may be a promising therapeutic strategy to treat patients with NSCLCs harboring EGFR mutations.

A Novel DNA Methylation-Based Signature Can Predict the Responses of MGMT Promoter Unmethylated Glioblastomas to Temozolomide

Glioblastoma (GBM) is the most malignant glioma, with a median overall survival (OS) of 14–16 months. Temozolomide (TMZ) is the first-line chemotherapy drug for glioma, but whether TMZ should be withheld from patients with GBMs that lack O6-methylguanine-DNA methyltransferase (MGMT) promoter methylation is still under debate. DNA methylation profiling holds great promise for further stratifying the responses of MGMT promoter unmethylated GBMs to TMZ. In this study, we studied 147 TMZ-treated MGMT promoter unmethylated GBM, whose methylation information was obtained from the HumanMethylation27 (HM-27K) BeadChips (n = 107) and the HumanMethylation450 (HM-450K) BeadChips (n = 40) for training and validation, respectively. In the training set, we performed univariate Cox regression and identified that 3,565 CpGs were significantly associated with the OS of the TMZ-treated MGMT promoter unmethylated GBMs. Functional analysis indicated that the genes corresponding to these CpGs were enriched in the biological processes or pathways of mitochondrial translation, cell cycle, and DNA repair. Based on these CpGs, we developed a 31-CpGs methylation signature utilizing the least absolute shrinkage and selection operator (LASSO) Cox regression algorithm. In both training and validation datasets, the signature identified the TMZ-sensitive GBMs in the MGMT promoter unmethylated GBMs, and only the patients in the low-risk group appear to benefit from the TMZ treatment. Furthermore, these identified TMZ-sensitive MGMT promoter unmethylated GBMs have a similar OS when compared with the MGMT promoter methylated GBMs after TMZ treatment in both two datasets. Multivariate Cox regression demonstrated the independent prognostic value of the signature in TMZ-treated MGMT promoter unmethylated GBMs. Moreover, we also noticed that the hallmark of epithelial–mesenchymal transition, ECM related biological processes and pathways were highly enriched in the MGMT unmethylated GBMs with the high-risk score, indicating that enhanced ECM activities could be involved in the TMZ-resistance of GBM. In conclusion, our findings promote our understanding of the roles of DNA methylation in MGMT umethylated GBMs and offer a very promising TMZ-sensitivity predictive signature for these GBMs that could be tested prospectively.

A Compound AC1Q3QWB Selectively Disrupts HOTAIR-Mediated Recruitment of PRC2 and Enhances Cancer Therapy of DZNep

Over 20% of cancer 'driver' genes encode chromatin regulators. Long noncoding RNAs (lincRNAs), which are dysregulated in various cancers, play a critical role in chromatin dynamics and gene regulation by interacting with key epigenetic regulators. It has been previously reported that the lincRNA HOTAIR mediates recruitment of polycomb repressive complex 2 (PRC2) leading to aberrant transcriptional silencing of tumor suppressor genes in glioma and breast cancer. Thus, lincRNA HOTAIR can serve as a promising therapeutic target. Herein, we identified a small-molecule compound AC1Q3QWB (AQB) as a selective and efficient disruptor of HOTAIR-EZH2 interaction, resulting in blocking of PRC2 recruitment and increasing tumor suppressors expression.

Methods: Molecular docking and high-throughput screening were performed to identify the small compound, AQB. RIP and ChIRP assays were carried to assess the selective interference of AQB with the HOTAIR-EZH2 interaction. The effects of AQB on tumor malignancy were evaluated in a variety of cancer cell lines and orthotopic breast cancer models. The combination therapy of AQB and 3-Deazaneplanocin A (DZNep), an inhibitor of the histone methyltransferase EZH2 was used in vitro and in orthotopic breast cancer and glioblastoma patient-derived xenograft (PDX) models.

Results: Tumor cells highly expressing HOTAIR and EZH2 were sensitive to AQB. APC2, as one of the target genes, was significantly up-regulated by AQB and led to degradation of β-catenin resulting in suppression of Wnt/β-catenin signaling which may contribute to inhibition of tumor growth and metastasis in vitro and in orthotopic breast cancer models. Remarkably, AQB enhanced the toxicity of DZNep in vitro. In orthotopic breast cancer and glioblastoma patient-derived xenografts (PDX) models, the combination of low doses of AQB and DZNep realized much better killing than DZNep treatment alone.

Conclusion: AQB is a HOTAIR-EZH2 inhibitor, which blocks PRC2 recruitment and has great potential as an effective agent for targeted cancer therapy.

HERC3-Mediated SMAD7 Ubiquitination Degradation Promotes Autophagy-Induced EMT and Chemoresistance in Glioblastoma

PURPOSE

Glioblastoma, a common malignant intracranial tumor, has the most dismal prognosis. Autophagy was reported to act as a survival-promoting mechanism in gliomas by inducing epithelial-to-mesenchymal transition (EMT). Here, we determined the critical molecules involved in autophagy-induced EMT and elucidated the possible mechanism of chemoradiotherapy resistance and tumor recurrence.

EXPERIMENTAL DESIGN

We used isobaric tags for relative and absolute quantitation to identify the critical proteins and pathway mediating EMT via autophagy inducer treatment, and tested the expression of these proteins using tissue microarray of gliomas and clinical glioblastoma samples as well as tissues and cells separated from the core lesion and tumor-peripheral region. Analysis of the Cancer Genome Atlas database and 110 glioblastoma cases revealed the prognostic value of these molecules. The functional role of these critical molecules was further confirmed by in vitro experiments and intracranial xenograft in nude mice.

RESULTS

Autophagy inducers significantly upregulated the expression of HERC3, which promotes ubiquitination-mediated degradation of SMAD7 in an autolysosome-dependent manner. The corresponding increase in p-SMAD2/3 level and TGFβ pathway activation finally induced EMT in cell lines and primary glioblastoma cells. Moreover, HERC3 overexpression was observed in pseudo-palisade cells surrounding tumor necrosis and in tumor-adjacent tissue; high HERC3 and low SMAD7 levels predicted poor clinical outcome in glioblastoma; xenograft of nude mice and in vitro experiments confirmed these findings.

CONCLUSIONS

Together, our findings reveal the indispensable role of HERC3 in regulating canonical SMAD2/3-dependent TGFβ pathway involvement in autophagy-induced EMT, providing insights toward a better understanding of the mechanism of resistance to temozolomide and peripheral recurrence of glioblastoma.