NKD1 marks intestinal and liver tumors linked to aberrant Wnt signaling

Mechanical Regulation of Mitochondrial Dynamics and Function in a 3D-Engineered Liver Tumor Microenvironment

It has become evident that physical stimuli of the cellular microenvironment transmit mechanical cues regulating key cellular functions, such as proliferation, migration, and malignant transformation. Accumulating evidence suggests that tumor cells face variable mechanical stimuli that may induce metabolic rewiring of tumor cells. However, the knowledge of how tumor cells adapt metabolism to external mechanical cues is still limited. We therefore designed soft 3D collagen scaffolds mimicking a pathological mechanical environment to decipher how liver tumor cells would adapt their metabolic activity to physical stimuli of the cellular microenvironment. Here, we report that the soft 3D microenvironment upregulates the glycolysis of HepG2 and Alexander cells. Both cell lines adapt their mitochondrial activity and function under growth in the soft 3D microenvironment. Cells grown in the soft 3D microenvironment exhibit marked mitochondrial depolarization, downregulation of mitochondrially encoded cytochrome c oxidase I, and slow proliferation rate in comparison with stiff monolayer cultures. Our data reveal the coupling of liver tumor glycolysis to mechanical cues. It is proposed here that soft 3D collagen scaffolds can serve as a useful model for future studies of mechanically regulated cellular functions of various liver (potentially other tissues as well) tumor cells.

Clinical Significance of NKD Inhibitor of WNT Signaling Pathway 1 (NKD1) in Glioblastoma

Introduction. As the most malignant type of gliomas, glioblastoma is characterized with disappointing prognosis. Here, we aimed to investigate expression and function of NKD inhibitor of Wnt signaling pathway 1 (NKD1), an antagonist of Wnt-beta-catenin signaling pathways, in glioblastoma. Methods. The mRNA level of NKD1 was firstly retrieved from TCGA glioma dataset to evaluate its correlation with clinical characteristics and its value in prognosis prediction. Then, its protein expression level in glioblastoma was tested by immunohistochemistry staining in a retrospectively cohort collected from our medical center (n = 66). Univariate and multivariate survival analyses were conducted to assess its effect on glioma prognosis. Two glioblastoma cell lines, U87 and U251, were used to further investigate the tumor-related role of NKD1 through overexpression strategy in combination with cell proliferation assays. Immune cell enrichment in glioblastoma and its correlation with NKD1 level was finally assessed using bioinformatics analyses. Results. NKD1 shows a lower expression level in glioblastoma compared to that in the normal brain or other glioma subtypes, which is independently correlated to a worse prognosis in both the TCGA cohort and our retrospective cohort. Overexpressing NKD1 in glioblastoma cell lines can significantly attenuate cell proliferation. In addition, expression of NKD1 in glioblastoma is negatively correlated to the T cell infiltration, indicating it may have crosstalk with the tumor immune microenvironment. Conclusions. NKD1 inhibits glioblastoma progression and its downregulated expression indicates a poor prognosis.

TROP2 Represents a Negative Prognostic Factor in Colorectal Adenocarcinoma and Its Expression Is Associated with Features of Epithelial-Mesenchymal Transition and Invasiveness

Trophoblastic cell surface antigen 2 (TROP2) is a membrane glycoprotein overexpressed in many solid tumors with a poor prognosis, including intestinal neoplasms. In our study, we show that TROP2 is expressed in preneoplastic lesions, and its expression is maintained in most colorectal cancers (CRC). High TROP2 positivity correlated with lymph node metastases and poor tumor differentiation and was a negative prognostic factor. To investigate the role of TROP2 in intestinal tumors, we analyzed two mouse models with conditional disruption of the adenomatous polyposis coli (Apc) tumor-suppressor gene, human adenocarcinoma samples, patient-derived organoids, and TROP2-deficient tumor cells. We found that Trop2 is produced early after Apc inactivation and its expression is associated with the transcription of genes involved in epithelial-mesenchymal transition, the regulation of migration, invasiveness, and extracellular matrix remodeling. A functionally similar group of genes was also enriched in TROP2-positive cells from human CRC samples. To decipher the driving mechanism of TROP2 expression, we analyzed its promoter. In human cells, this promoter was activated by β-catenin and additionally by the Yes1-associated transcriptional regulator (YAP). The regulation of TROP2 expression by active YAP was verified by YAP knockdown in CRC cells. Our results suggest a possible link between aberrantly activated Wnt/β-catenin signaling, YAP, and TROP2 expression.

Identification of colon tumor marker NKD1 via integrated bioinformatics analysis and experimental validation

Background

Colorectal cancer is an important death‐related disease in the worldwide. However, specific colon cancer tumor markers currently used for diagnosis and treatment are few. The purpose of this study is to screen the potential colon cancer markers by bioinformatics and verify the results with experiments.

Methods

Gene expression data were downloaded from two different databases: TCGA database and GEO datasets, which were then analyzed by two different methods (difference analysis and WGCNA method). Venn and PPI analysis obtained the potential core genes, which were then performed the GO enrichment and KEGG pathway analysis. Expressions levels of NKD1 in colon carcinoma tissues were further confirmed by immunohistochemical staining and western blot assays. Moreover, the function was measured by MTT, clone formation, and tumor transplantation experiments. Importantly, co‐immunoprecipitation, immunofluorescence, and protein stability assays were further performed to explore the underlying mechanism of NKD1 promoting cell proliferation.

Results

Nine potential core genes highly expressed in colon cancer samples were screened out by bioinformatics analysis. NKD1, one of the hub genes, highly expressed in the colon carcinoma tissues could enhance the proliferation of colon cancer cells. Mechanism research demonstrated that NKD1 was essential for the combination between Wnt signalosome (DVL) and β‐catenin, and that NKD1 knockout remarkably decreased the β‐catenin expression. Immunofluorescence assays further implied that NKD1 knockout significantly inhibited β‐catenin nuclear accumulation. Importantly, the stability of β‐catenin proteins was maintained by NKD1 in the colon cancer cells.

Conclusion

We believe that NKD1 well expressed in the colorectal carcinoma tissues can enhance the proliferation of colon cancer cells. Furthermore, the functions that NKD1 may have in colon cancer cells should be different from that NKD1 has played in the zebrafish. Thus, NKD1 could be a specific colorectal cancer marker.

Analysis of open chromatin regions in bladder cancer links β-catenin mutations and Wnt signaling with neuronal subtype of bladder cancer

Urothelial carcinoma of the bladder is the most frequent bladder cancer affecting more than 400,000 people each year. Histopathologically, it is mainly characterized as muscle invasive bladder cancer (MIBC) and non-muscle invasive bladder cancer (NMIBC). Recently, the studies largely driven by consortiums such as TCGA identified the mutational landscape of both MIBC and NMIBC and determined the molecular subtypes of bladder cancer. Because of the exceptionally high rate of mutations in chromatin proteins, bladder cancer is thought to be a disease of chromatin, pointing out to the importance of studying epigenetic deregulation and the regulatory landscape of this cancer. In this study, we have analyzed ATAC-seq data generated for MIBC and integrated our findings with gene expression and DNA methylation data to identify subgroup specific regulatory patterns for MIBC. Our computational analysis revealed three MIBC regulatory clusters, which we named as neuronal, non-neuronal and luminal outlier. We have identified target genes of neuronal regulatory elements to be involved in WNT signaling, while target genes of non-neuronal and luminal outlier regulatory regions were enriched in epithelial differentiation and drug metabolism, respectively. Neuronal regulatory elements were determined to be ß-catenin targets (p value = 3.59e−08) consisting of genes involved in neurogenesis such as FGF9, and PROX1, and significantly enriched for TCF/LEF binding sites (p value = 1e−584). Our results showed upregulation of ß-catenin targets regulated by neuronal regulatory elements in three different cohorts, implicating ß-catenin signature in neuronal bladder cancer. Further, integration with mutation data revealed significantly higher oncogenic exon 3 ß-catenin mutations in neuronal bladder cancer compared to non-neuronal (odds ratio = 31.33, p value = 1.786e−05). Our results for the first time identify regulatory elements characterizing neuronal bladder cancer and links these neuronal regulatory elements with WNT signaling via mutations in β-catenin and its destruction complex components.

Truncated PPM1D impairs stem cell response to genotoxic stress and promotes growth of APC-deficient tumors in the mouse colon

Protein phosphatase magnesium-dependent 1 delta (PPM1D) terminates cell response to genotoxic stress by negatively regulating the tumor suppressor p53 and other targets at chromatin. Mutations in the exon 6 of the PPM1D result in production of a highly stable, C-terminally truncated PPM1D. These gain-of-function PPM1D mutations are present in various human cancers but their role in tumorigenesis remains unresolved. Here we show that truncated PPM1D impairs activation of the cell cycle checkpoints in human non-transformed RPE cells and allows proliferation in the presence of DNA damage. Next, we developed a mouse model by introducing a truncating mutation in the PPM1D locus and tested contribution of the oncogenic PPM1D^T allele to colon tumorigenesis. We found that p53 pathway was suppressed in colon stem cells harboring PPM1D^T resulting in proliferation advantage under genotoxic stress condition. In addition, truncated PPM1D promoted tumor growth in the colon in Apc^min mice and diminished survival. Moreover, tumor organoids derived from colon of the Apc^minPpm1d^T/+ mice were less sensitive to 5-fluorouracil when compared to Apc^minPpm1d^+/+and the sensitivity to 5-fluorouracil was restored by inhibition of PPM1D. Finally, we screened colorectal cancer patients and identified recurrent somatic PPM1D mutations in a fraction of colon adenocarcinomas that are p53 proficient and show defects in mismatch DNA repair. In summary, we provide the first in vivo evidence that truncated PPM1D can promote tumor growth and modulate sensitivity to chemotherapy.

A tannin compound from Sanguisorba officinalis blocks Wnt/β-catenin signaling pathway and induces apoptosis of colorectal cancer cells

BACKGROUND

Sanguisorba officinalis, a popular Chinese herb, called DiYu, has been shown to inhibit the growth of many human cancer cell lines, including colorectal cancer cells. The aims of this study were to discover the active compound and molecular mechanism of S. officinalis against Wnt/β-catenin signaling pathway and develop Wnt inhibitors from natural products as anti-colorectal cancer agents.

METHODS

1,4,6-Tri-O-galloyl-β-d-glucopyranose (TGG) was obtained by the preparative HPLC. The effect of DiYu on proliferation of NIH3T3 and HT29 was detected by MTT assay. Luciferase reporter assay was applied to investigate the activity of Wnt/β-catenin signaling in NIH3T3. The expression levels of mRNA and protein were detected by RT-PCR and western blot. Immunofluorescence assay was used to measure the level of β-catenin in cytoplasm and nucleus. Transcriptomic profiling study was performed to investigate the molecular mechanism of DiYu on the Wnt/β-catenin signaling pathway.

RESULTS

TGG significantly inhibited the Wnt/β-catenin signaling pathway, down-regulated the expression of β-catenin and Wnt target genes (Dkk1, c-Myc, FGF20, NKD1, Survivin), up-regulated the levels of cleaved caspase3, cleaved PARP and ratio of Bax/Bcl-2, which may explain the apoptosis of HT29.

CONCLUSIONS

Our study enhanced the discovery of the materials and elucidation of mechanisms that account for the anti-Wnt activity of natural inhibitor (DiYu) and identified the potential of TGG to be developed as anti-colorectal cancer drugs.

Novel Thienopyrimidine Derivative, RP-010, Induces β-Catenin Fragmentation and Is Efficacious against Prostate Cancer Cells

Thienopyrimidines containing a thiophene ring fused to pyrimidine are reported to have a wide-spectrum of anticancer efficacy in vitro. Here, we report for the first time that thieno[3,2-d]pyrimidine-based compounds, also known as the RP series, have efficacy in prostate cancer cells. The compound RP-010 was efficacious against both PC-3 and DU145 prostate cancer (PC) cells (IC₅₀ < 1 µM). The cytotoxicity of RP-010 was significantly lower in non-PC, CHO, and CRL-1459 cell lines. RP-010 (0.5, 1, 2, and 4 µM) arrested prostate cancer cells in G2 phase of the cell cycle, and induced mitotic catastrophe and apoptosis in both PC cell lines. Mechanistic studies suggested that RP-010 (1 and 2 µM) affected the wingless-type MMTV (Wnt)/β-catenin signaling pathway, in association with β-catenin fragmentation, while also downregulating important proteins in the pathway, including LRP-6, DVL3, and c-Myc. Interestingly, RP-010 (1 and 2 µM) induced nuclear translocation of the negative feedback proteins, Naked 1 and Naked 2, in the Wnt pathway. In addition, RP-010 (0.5, 1, 2 and 4 µM) significantly decreased the migration of PC cells in vitro. Finally, RP-010 did not produce significant toxic effects in zebrafish at concentrations of up to 6 µM. In conclusion, RP-010 may be an efficacious and relatively nontoxic anticancer compound for prostate cancer. Future mechanistic and in vivo efficacy studies are needed to optimize the hit compound RP-010 for lead optimization and clinical use.

Integrated analysis of dosage effect lncRNAs in lung adenocarcinoma based on comprehensive network

Accumulating evidences indicate that cancer-related lncRNAs occur frequent somatic copy number alternation (SCNA). Although individual SCNA lncRNAs have been implicated in tumor biology, their regulatory mechanism has not been assessed in a systematic way. In order to explore the expression characteristics and biological functions of SCNA lncRNAs in cancer, we built a computational framework based on lncRNA expression profiles, lncRNA copy numbers and dosage sensitivity score (DSS). First, we found that the lncRNAs with different DSS were involved in distinct biological processes, while those with the same DSS had similar functions. Second, some of the lncRNAs participated in the progression and metastasis of lung adenocarcinoma (LUAD) through cis-acting regulation. In lncRNA-TF-mRNA network, lncRNAs interacted with 4 TFs and affected the immune system, and further influenced LUAD progression. Third, competing endogenous RNA network analysis inferred that lncRNA ENSG00000240990 competed with HOXA10 to absorb hsa-let-7a/b/f/g-5p and affected patient prognosis in LUAD. Last but not least, by integrating target information of miRNA we also provided a new perspective for the discovery of potential small molecule drugs. In summary, we systematically analyzed the regulatory role of SCNA lncRNAs. This work may facilitate cancer research and serve as the basis for future efforts to understand the role of SCNA lncRNAs, develop novel biomarkers and improve knowledge of tumor biology.

Pan-cancer transcriptomic analysis associates long non-coding RNAs with key mutational driver events

Thousands of long non-coding RNAs (lncRNAs) lie interspersed with coding genes across the genome, and a small subset has been implicated as downstream effectors in oncogenic pathways. Here we make use of transcriptome and exome sequencing data from thousands of tumours across 19 cancer types, to identify lncRNAs that are induced or repressed in relation to somatic mutations in key oncogenic driver genes. Our screen confirms known coding and non-coding effectors and also associates many new lncRNAs to relevant pathways. The associations are often highly reproducible across cancer types, and while many lncRNAs are co-expressed with their protein-coding hosts or neighbours, some are intergenic and independent. We highlight lncRNAs with possible functions downstream of the tumour suppressor TP53 and the master antioxidant transcription factor NFE2L2. Our study provides a comprehensive overview of lncRNA transcriptional alterations in relation to key driver mutational events in human cancers.

Long non-coding RNAs are implicated in multiple aspects of tumourigenesis. Here, the authors generate a landscape of these macromolecules in a wide array of cancer types and examine which RNAs are transcriptionally altered in relation to somatic driver mutations in established coding cancer genes.

The NKD1/Rac1 feedback loop regulates the invasion and migration ability of hepatocarcinoma cells

Hepatocellular carcinoma (HCC) is complicated by aggressive migration and invasion, which contribute to the increased mortality of HCC patients. The NKD1 protein is abnormally expressed in many neoplasms and plays an important role in tumor progression. However, the regulation and underlying molecular mechanisms of NKD1 in HCC cell invasion and migration remain poorly understood. In the present study, ectopic expression of NKD1 in HCC cells attenuated migration and invasion in vitro and in vivo by down-regulating Rac1 expression level and activity, which affected the HCC cell cytoskeleton and E-cadherin expression. Mechanistic studies showed that NKD1 interacted with Rac1 in the cytoplasm and promoted its degradation by the ubiquitin-proteasome pathway. Over-expression of Rac1 enhanced the transcription of the NKD1 gene and protein expression conversely owing to its negative regulation of EZH2. Analysis of clinical samples showed that abnormal expression of NKD1 and Rac1 was associated with the poor prognosis of HCC patients. In summary, our data indicate a new role for NKD1 as a regulator of HCC cell invasion and migration via a feedback loop involving Rac1.

The potential role of liver stem cells in initiation of primary liver cancer

Identification of the cellular origin of primary liver cancer remains challenging. Some data point toward liver stem cells (LSCs) or liver progenitor cells (LPCs) not only as propagators of liver regeneration, but also as initiators of liver cancer. LSCs exhibit a long lifespan and strong duplicative potential upon activation and are inclined to accumulate more mutations that can be passed down to the next generations. Recent evidence shows that dysregulation of signaling pathways associated with self-renewal of LSCs can drive their aberrant proliferation and even malignant transformation. If LSCs could be proved to be an initiator of liver carcinogenesis, they would be promising for ultra-early diagnosis and targeting therapy of liver cancer. This review mainly summarizes the potential role of LSCs in the carcinogenesis of primary liver cancer.

Wnt Signaling Inhibition Deprives Small Intestinal Stem Cells of Clonogenic Capacity

The Wnt pathway plays a crucial role in self‐renewal and differentiation of cells in the adult gut. In the present study, we revealed the functional consequences of inhibition of canonical Wnt signaling in the intestinal epithelium. The study was based on generation of a novel transgenic mouse strain enabling inducible expression of an N‐terminally truncated variant of nuclear Wnt effector T cell factor 4 (TCF4). The TCF4 variant acting as a dominant negative (dn) version of wild‐type (wt) TCF4 protein decreased transcription of β‐catenin‐TCF4‐responsive genes. Interestingly, suppression of Wnt/β‐catenin signaling affected asymmetric division of intestinal stem cells (ISCs) rather than proliferation. ISCs expressing the transgene underwent several rounds of division but lost their clonogenic potential and migrated out of the crypt. Expression profiling of crypt cells revealed that besides ISC‐specific markers, the dnTCF4 production downregulated expression levels of epithelial genes produced in other crypt cells including markers of Paneth cells. Additionally, in Apc conditional knockout mice, dnTCF activation efficiently suppressed growth of Apc‐deficient tumors. In summary, the generated mouse strain represents a convenient tool to study cell‐autonomous inhibition of β‐catenin‐Tcf‐mediated transcription. genesis 54:101–114, 2016. © 2016 The Authors genesis Published by Wiley Periodicals, Inc.

Wnt ligand-dependent activation of the negative feedback regulator Nkd1

Nkd1, a negative feedback regulator of the Wnt pathway, localizes with Dvl2 to the putative Wnt signalosome, where it becomes activated by Wnt. Activated Nkd1 moves away from the membrane to become more cytosolic, where it interacts with β-catenin to prevent nuclear accumulation.

Misregulation of Wnt signaling is at the root of many diseases, most notably colorectal cancer, and although we understand the activation of the pathway, we have a very poor understanding of the circumstances under which Wnt signaling turns itself off. There are numerous negative feedback regulators of Wnt signaling, but two stand out as constitutive and obligate Wnt-induced regulators: Axin2 and Nkd1. Whereas Axin2 behaves similarly to Axin in the destruction complex, Nkd1 is more enigmatic. Here we use zebrafish blastula cells that are responsive Wnt signaling to demonstrate that Nkd1 activity is specifically dependent on Wnt ligand activation of the receptor. Furthermore, our results support the hypothesis that Nkd1 is recruited to the Wnt signalosome with Dvl2, where it becomes activated to move into the cytoplasm to interact with β-catenin, inhibiting its nuclear accumulation. Comparison of these results with Nkd function in Drosophila generates a unified and conserved model for the role of this negative feedback regulator in the modulation of Wnt signaling.