Insights into developmental mechanisms and cancers in the mammalian intestine derived from serial analysis of gene expression and study of the hepatoma-derived growth factor (HDGF)

HDGF Knockout Suppresses Colorectal Cancer Progression and Drug Resistance by Modulating the DNA Damage Response

Colorectal cancer (CRC) is a highly heterogeneous gastrointestinal malignancy. Despite significant advances in molecular targeted therapies for CRC in recent years, the increase in the overall survival rates for CRC patients remains limited. Therefore, there is an urgent need to explore novel drug targets. Herein, we show that heparin binding growth factor (HDGF) is highly expressed in CRC, and that its overexpression is associated with a poor disease-free interval. Additionally, we reveal that HDGF knockout reduces proliferation, migration, and invasion, while enhancing apoptosis in CRC cells, thereby validating HDGF as a potential therapeutic target for CRC. Mechanistically, we found that HDGF modulates DNA damage response and, by recruiting C-terminal binding protein-interacting protein (CtIP), it facilitates homologous recombination repair to influence CRC drug sensitivity. Furthermore, we propose that HDGF may serve as a recognition protein for H3K36me3, participating in the repair of damaged transcriptionally active genes, thus maintaining genomic stability in CRC.

The expression spectrum of yak epididymal epithelial cells reveals the functional diversity of caput, corpus and cauda regions

Sperm undergo a series of changes in the epididymis region before acquiring the ability to move and fertilize, and the identification of genes expressed in a region-specific manner in the epididymis provides a valuable insight into functional differences between regions. We collected epididymal tissue from three yaks and cultured epithelial cells from the caput, corpus and cauda regions of the yak epididymis using the tissue block method. RNA sequencing analysis (RNA-seq) technology was used to detect gene expression in yak epididymal caput, corpus and cauda epithelial cells. The results showed that the DEGs were highest in the caput vs. corpus comparison, and lowest in the corpus vs. cauda comparison. Six DEGs were verified by real-time fluorescence quantitative PCR (qRT-PCR), consistent with transcriptome sequencing results. The significantly enriched DNA replication pathway in the caput vs. corpus was coordinated with cell proliferation, while upregulated DEGs such as POLD1 and MCM4 were found in the DNA replication pathway. The AMPK signaling pathway was found significantly enriched in the caput vs cauda, suggesting its involvement in sperm maturation and capacitation. The TGF beta signaling pathway was screened in the corpus vs cauda and is crucial for mammalian reproductive regulation. Upregulated DEGs (TGFB3, INHBA, INHBB) are involved in the TGF beta signaling pathway. This study provides a reference for culturing yak epididymal epithelial cells in vitro, and elucidates the transcriptional profiles of epithelial cells in different segments of the epididymis, revealing the regulatory and functional differences between different segments, providing basic data for exploring the molecular mechanism of yak sperm maturation and improving the reproductive capacity of high-altitude mammals.

Development of a novel embryonic germline gene-related prognostic model of lung adenocarcinoma

BACKGROUND

Emerging evidence implicates the correlation of embryonic germline genes with the tumor progress and patient's outcome. However, the prognostic value of these genes in lung adenocarcinoma (LUAD) has not been fully studied. Here we systematically evaluated this issue, and constructed a novel signature and a nomogram associated with embryonic germline genes for predicting the outcomes of lung adenocarcinoma.

METHODS

The LUAD cohorts retrieved from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) database were used as training set and testing set, respectively. The embryonic germline genes were downloaded from the website https://venn.lodder.dev. Then, the differentially expressed embryonic germline genes (DEGGs) between the tumor and normal samples were identified by limma package. The functional enrichment and pathway analyses were also performed by clusterProfiler package. The prognostic model was constructed by the least absolute shrinkage and selection operator (LASSO)-Cox regression method. Survival and Receiver Operating Characteristic (ROC) analyses were performed to validate the model using training set and four testing GEO datasets. Finally, a prognostic nomogram based on the signature genes was constructed using multivariate regression method.

RESULTS

Among the identified 269 DEGGs, 249 were up-regulated and 20 were down-regulated. GO and KEGG analyses revealed that these DEGGs were mainly enriched in the process of cell proliferation and DNA damage repair. Then, 103 DEGGs with prognostic value were identified by univariate Cox regression and further filtered by LASSO method. The resulting sixteen DEGGs were included in step multivariate Cox regression and an eleven embryonic germline gene related signature (EGRS) was constructed. The model could robustly stratify the LUAD patients into high-risk and low-risk groups in both training and testing sets, and low-risk patients had much better outcomes. The multi-ROC analysis also showed that the EGRS model had the best predictive efficacy compared with other common clinicopathological factors. The EGRS model also showed robust predictive ability in four independent external datasets, and the area under curve (AUC) was 0.726 (GSE30219), 0.764 (GSE50081), 0.657 (GSE37745) and 0.668 (GSE72094). More importantly, the expression level of some genes in EGRS has a significant correlation with the progression of LUAD clinicopathology, suggesting these genes might play an important role in the progression of LUAD. Finally, based on EGRS genes, we built and calibrated a nomogram for conveniently evaluating patients' outcomes.

The Interplay between Nutrition, Innate Immunity, and the Commensal Microbiota in Adaptive Intestinal Morphogenesis

The gastrointestinal tract is a functionally and anatomically segmented organ that is colonized by microbial communities from birth. While the genetics of mouse gut development is increasingly understood, how nutritional factors and the commensal gut microbiota act in concert to shape tissue organization and morphology of this rapidly renewing organ remains enigmatic. Here, we provide an overview of embryonic mouse gut development, with a focus on the intestinal vasculature and the enteric nervous system. We review how nutrition and the gut microbiota affect the adaptation of cellular and morphologic properties of the intestine, and how these processes are interconnected with innate immunity. Furthermore, we discuss how nutritional and microbial factors impact the renewal and differentiation of the epithelial lineage, influence the adaptation of capillary networks organized in villus structures, and shape the enteric nervous system and the intestinal smooth muscle layers. Intriguingly, the anatomy of the gut shows remarkable flexibility to nutritional and microbial challenges in the adult organism.

PRAP1 is a novel lipid-binding protein that promotes lipid absorption by facilitating MTTP-mediated lipid transport

Microsomal triglyceride transfer protein (MTTP) is an endoplasmic reticulum resident protein that is essential for the assembly and secretion of triglyceride (TG)-rich, apoB-containing lipoproteins. Although the function and structure of mammalian MTTP have been extensively studied, how exactly MTTP transfers lipids to lipid acceptors and whether there are other biomolecules involved in MTTP-mediated lipid transport remain elusive. Here we identify a role in this process for the poorly characterized protein PRAP1. We report that PRAP1 and MTTP are partially colocalized in the endoplasmic reticulum. We observe that PRAP1 directly binds to TG and facilitates MTTP-mediated lipid transfer. A single amino acid mutation at position 85 (E85V) impairs PRAP1's ability to form a ternary complex with TG and MTTP, as well as impairs its ability to facilitate MTTP-mediated apoB-containing lipoprotein assembly and secretion, suggesting that the ternary complex formation is required for PRAP1 to facilitate MTTP-mediated lipid transport. PRAP1 is detectable in chylomicron/VLDL-rich plasma fractions, suggesting that MTTP recognizes PRAP1-bound TG as a cargo and transfers TG along with PRAP1 to lipid acceptors. Both PRAP1-deficient and E85V knock-in mutant mice fed a chow diet manifested an increase in the length of their small intestines, likely to compensate for challenges in absorbing lipid. Interestingly, both genetically modified mice gained significantly less body weight and fat mass when on high-fat diets compared with littermate controls and were prevented from hepatosteatosis. Together, this study provides evidence that PRAP1 plays an important role in MTTP-mediated lipid transport and lipid absorption.

Identification of a stool long non-coding RNAs panel as a potential biomarker for early detection of colorectal cancer

Background

The feces of colorectal cancer (CRC) patients contain tumor colonocytes, which constantly shed into the lumen area. Therefore, stool evaluation can be considered as a rapid and low‐risk way to directly determine the colon and rectum status. As long non‐coding RNAs (lncRNAs) alterations are important in cancer cells fate regulation, we aimed to assess the level of a panel of cancer‐related lncRNAs in fecal colonocytes.

Methods

The population study consisted of 150 subjects, including a training set, a validation set, and a group of 30 colon polyps. The expression levels of lncRNAs were evaluated by quantitative real‐time PCR (qRT‐PCR). The NPInetr and EnrichR tools were used to identify the interactions and functions of lncRNAs.

Results

A total of 10 significantly dysregulated lncRNAs, including CCAT1, CCAT2, H19, HOTAIR, HULC, MALAT1, PCAT1, MEG3, PTENP1, and TUSC7, were chosen for designing a predictive panel. The diagnostic performance of the panel in distinguishing CRCs from the healthy group was AUC: 0.8554 in the training set and 0.8465 in the validation set. The AUC for early CRCs (I‐II TNM stages) was 0.8554 in the training set and 0.8465 in the validation set, and for advanced CRCs (III‐IV TNM stages) were 0.9281 in the training set and 0.9236 in the validation set. The corresponding AUC for CRCs vs polyps were 0.9228 (I‐IV TNM stages), 0.9042 (I‐II TNM stages), and 0.9362 (III‐IV TNM stages).

Conclusions

These data represented the application of analysis of fecal colonocytes lncRNAs in early detection of CRC.

Hepatoma-Derived Growth Factor: An Overview and Its Role as a Potential Therapeutic Target Molecule for Digestive Malignancies

Hepatoma-derived growth factor (HDGF) was identified in research seeking to find a novel growth factor for hepatoma cells. Subsequently, four HDGF-related proteins were identified, and these proteins are considered to be members of a new gene family. HDGF has a growth-stimulating role, an angiogenesis-inducing role, and a probable anti-apoptotic role. HDGF is ubiquitously expressed in non-cancerous tissues, and participates in organ development and in the healing of damaged tissues. In addition, the high expression of HDGF was reported to be closely associated with unfavorable clinical outcomes in several malignant diseases. Thus, HDGF is considered to contribute to the development and progression of malignant disease. We herein provide a brief overview of the factor and its functions in relation to benign and malignant cells. We also describe its possible role as a target molecule for digestive malignancies.

A Quantitative Framework for Evaluating Single-Cell Data Structure Preservation by Dimensionality Reduction Techniques

High-dimensional data, such as those generated by single-cell RNA sequencing (scRNA-seq), present challenges in interpretation and visualization. Numerical and computational methods for dimensionality reduction allow for low-dimensional representation of genome-scale expression data for downstream clustering, trajectory reconstruction, and biological interpretation. However, a comprehensive and quantitative evaluation of the performance of these techniques has not been established. We present an unbiased framework that defines metrics of global and local structure preservation in dimensionality reduction transformations. Using discrete and continuous real-world and synthetic scRNA-seq datasets, we show how input cell distribution and method parameters are largely determinant of global, local, and organizational data structure preservation by 11 common dimensionality reduction methods.

TFAM is required for maturation of the fetal and adult intestinal epithelium

During development, the embryo transitions from a metabolism favoring glycolysis to a metabolism favoring mitochondrial respiration. How metabolic shifts regulate developmental processes, or how developmental processes regulate metabolic shifts, remains unclear. To test the requirement of mitochondrial function in developing endoderm-derived tissues, we genetically inactivated the mitochondrial transcription factor, Tfam, using the Shh-Cre driver. Tfam mutants did not survive postnatally, exhibiting defects in lung development. In the developing intestine, TFAM-loss was tolerated until late fetal development, during which the process of villus elongation was compromised. While progenitor cell populations appeared unperturbed, markers of enterocyte maturation were diminished and villi were blunted. Loss of TFAM was also tested in the adult intestinal epithelium, where enterocyte maturation was similarly dependent upon the mitochondrial transcription factor. While progenitor cells in the transit amplifying zone of the adult intestine remained proliferative, intestinal stem cell renewal was dependent upon TFAM, as indicated by molecular profiling and intestinal organoid formation assays. Taken together, these studies point to critical roles for the mitochondrial regulator TFAM for multiple aspects of intestinal development and maturation, and highlight the importance of mitochondrial regulators in tissue development and homeostasis.

Elevated FUS/TLS expression is negatively associated with E-cadherin expression and prognosis of patients with non-small cell lung cancer

Fused in sarcoma/translocated in liposarcoma (FUS/TLS), a ubiquitous and multifunctional DNA and RNA-binding protein, contributes an important function in cancer and neurodegenerative disease; however, its role in lung cancer remains unclear. In the present study, the expression of FUS/TLS in non-small cell lung cancer (NSCLC) and the significance of FUS/TLS for predicting the clinical outcome of patients with NSCLC, was examined. FUS/TLS expression was investigated in NSCLC tissues and their matched adjacent non-tumorous tissues by reverse transcription-quantitative polymerase chain reaction, western blotting, and immunohistochemistry. Tissue microarrays representing 208 patients with NSCLC were used to determine the expression pattern and associations with FUS/TLS using immunohistochemistry. Prognostic significance was assessed by Kaplan-Meier survival estimates and log-rank tests. Data revealed that FUS/TLS expression was elevated in NSCLC tissues compared with corresponding normal tissue mRNA (9.27±0.73 vs. 6.15±0.60) and protein (3.32±0.75 vs. 0.30±0.07) levels. In tissue microarrays, FUS/TLS was highly expressed in 103 (49.5%, 103/208) NSCLC tissues compared with adjacent normal lung tissues (28.4%, 59/208). Overexpression of FUS/TLS was associated with higher tumor node metastasis stage (P=0.016), poorer differentiation (P=0.008), large tumor size (P=0.019) and predicted poor prognosis (P=0.005) in patients with NSCLC. Notably, correlation analysis revealed a significant inverse association between the expression of FUS/TLS and E-cadherin (r²=0.51; P=0.036). Furthermore, patients with NSCLC with high FUS/TLS and impaired E-cadherin expression had a notably poor prognosis (P=4.01×10^-4). Thus, the results from the present study indicate that elevated FUS/TLS expression promotes NSCLC progression. FUS/TLS, alone or in combination with E-cadherin, is a novel prognostic predictor for patients with NSCLC.

Cyclic Mechanical Stretch Up-regulates Hepatoma-Derived Growth Factor Expression in Cultured Rat Aortic Smooth Muscle Cells

Hepatoma-derived growth factor (HDGF) is a potent mitogen for vascular smooth muscle cells (SMCs) during embryogenesis and injury repair of vessel walls. Whether mechanical stimuli modulate HDGF expression remains unknown. The present study aimed at investigating whether cyclic mechanical stretch plays a regulatory role in HDGF expression and regenerative cytokine production in aortic SMCs. A SMC cell line was grown on a silicone-based elastomer chamber with extracellular matrix coatings (either type I collagen or fibronectin) and received cyclic and uniaxial mechanical stretches with 10% deformation at frequency 1 Hz. Morphological observation showed that fibronectin coating provided better cell adhesion and spreading and that consecutive 6 h of cyclic mechanical stretch remarkably induced reorientation and realignment of SMCs. Western blotting detection demonstrated that continuous mechanical stimuli elicited up-regulation of HDGF and proliferative cell nuclear antigen, a cell proliferative marker. Signal kinetic profiling study indicated that cyclic mechanical stretch induced signaling activity in RhoA/ROCK and PI3K/Akt cascades. Kinase inhibition study further showed that blockade of PI3K activity suppressed the stretch-induced tumor necrosis factor-α (TNF-α), whereas RhoA/ROCK inhibition significantly blunted the interleukin-6 (IL-6) production and HDGF overexpression. Moreover, siRNA-mediated HDGF gene silencing significantly suppressed constitutive expression of IL-6, but not TNF-α, in SMCs. These findings support the role of HDGF in maintaining vascular expression of IL-6, which has been regarded a crucial regenerative factor for acute vascular injury. In conclusion, cyclic mechanical stretch may maintain constitutive expression of HDGF in vascular walls and be regarded an important biophysical regulator in vascular regeneration.

High Serum HDGF Levels Are Predictive of Bone Metastasis and Unfavorable Prognosis in Non-Small Cell Lung Cancer

Hepatoma-derived growth factor (HDGF) is a heparin-binding protein possessing mitogenic activity and could be secreted from necrotic cells passively or actively, thereby functioning as a damage-associated molecular pattern (DAMP). The high expression of HDGF in non-small cell lung cancer (NSCLC) tissues is associated with unfavorable prognosis. However, the clinical significance of serum HDGF has not been elucidated in NSCLC yet. In the present study, we compared the serum levels of HDGF in 235 patients with NSCLC (141 adenocarcinoma and 94 squamous cell carcinoma cases) with those in 40 healthy subjects. Moreover, we explored the correlation between serum HDGF levels and clinicopathologic factors or the overall survival rates. We thus found that the serum HDGF levels were significantly higher in NSCLC patients than those in healthy subjects (P < 0.001). Moreover, there was no significant difference in the serum HDGF levels between adenocarcinoma and squamous cell carcinoma. Importantly, the higher serum levels of HDGF were significantly associated with bone metastasis and with lower overall survival rates. Thus, serum HDGF was identified as an independent prognostic factor indicating poor prognosis of NSCLC. Using A549 human lung adenocarcinoma cell line, we demonstrated that an autophagy inhibitor, chloroquine, could inhibit the HDGF secretion, while quercetin, an autophagy inducer derived from a traditional Chinese drug, could facilitate HDGF secretion. In conclusion, high serum levels of HDGF were significantly correlated to bone metastasis and poorer prognosis of NSCLC. We suggest that anti-HDGF therapy is potential to protect NSCLC patients with advanced stages from bone metastasis.

Intra- or extra-exosomal secretion of HDGF isoforms: the extraordinary function of the HDGF-A N-terminal peptide

Hepatoma-derived growth factor (HDGF) is a protein with diverse intracellular functions. Moreover, after non-conventional secretion, extracellular HDGF is able to influence different signaling pathways, leading for example to induction of processes like epithelial-mesenchymal transition (EMT) and cell migration. Intriguingly, in recent proteome studies, HDGF was also found secreted by special microvesicles called exosomes. Recently, we demonstrated the existence of two new HDGF isoforms (B and C). These isoforms are involved in different cellular processes than HDGF-A. Along this line, in the present study we discovered that full length HDGF-A clearly is located inside of exosomes, whereas the isoforms HDGF-B and HDGF-C are found exclusively on the outer surface. Furthermore, while HDGF-B and HDGF-C seem to use exosomes mediated pathway exclusively, HDGF-A was found also as unbound protein in the conditioned media. The new finding of an intra- or extra-exosomal localisation of protein splice variants opens a fascinating new perspective concerning functional diversity of HDGF isoforms. Dysregulation of HDGF expression during cancer development and tumor progression is a commonly known fact. With our new findings, unraveling the potential functional impact according to physiological versus pathophysiologically altered levels and compositions of intra- and extra-exosomal HDGF has to be addressed in future studies.

Morphogenesis and maturation of the embryonic and postnatal intestine

The intestine is a vital organ responsible for nutrient absorption, bile and waste excretion, and a major site of host immunity. In order to keep up with daily demands, the intestine has evolved a mechanism to expand the absorptive surface area by undergoing a morphogenetic process to generate finger-like units called villi. These villi house specialized cell types critical for both absorbing nutrients from food, and for protecting the host from commensal and pathogenic microbes present in the adult gut. In this review, we will discuss mechanisms that coordinate intestinal development, growth, and maturation of the small intestine, starting from the formation of the early gut tube, through villus morphogenesis and into early postnatal life when the intestine must adapt to the acquisition of nutrients through food intake, and to interactions with microbes.

Two new isoforms of the human hepatoma-derived growth factor interact with components of the cytoskeleton

Hepatoma-derived growth factor (HDGF) is involved in diverse, apparently unrelated processes, such as cell proliferation, apoptosis, DNA-repair, transcriptional control, ribosome biogenesis and cell migration. Most of the interactions of HDGF with diverse molecules has been assigned to the hath region of HDGF. In this study we describe two previously unknown HDGF isoforms, HDGF-B and HDGF-C, generated via alternative splicing with structurally unrelated N-terminal regions of their hath region, which is clearly different from the well described isoform, HDGF-A. In silico modeling revealed striking differences near the PHWP motif, an essential part of the binding site for glycosaminoglycans and DNA/RNA. This observation prompted the hypothesis that these isoforms would have distinct interaction patterns with correspondingly diverse roles on cellular processes. Indeed, we discovered specific associations of HDGF-B and HDGF-C with cytoskeleton elements, such as tubulin and dynein, suggesting previously unknown functions of HDGF in retrograde transport, site directed localization and/or cytoskeleton organization. In contrast, the main isoform HDGF-A does not interact directly with the cytoskeleton, but via RNA with messenger ribonucleoprotein (mRNP) complexes. In summary, the discovery of HDGF splice variants with their discrete binding activities and subcellular distributions opened new avenues for understanding its biological function and importance.

A YY1-dependent increase in aerobic metabolism is indispensable for intestinal organogenesis

During late gestation, villi extend into the intestinal lumen to dramatically increase the surface area of the intestinal epithelium, preparing the gut for the neonatal diet. Incomplete development of the intestine is the most common gastrointestinal complication in neonates, but the causes are unclear. We provide evidence in mice that Yin Yang 1 (Yy1) is crucial for intestinal villus development. YY1 loss in the developing endoderm had no apparent consequences until late gestation, after which the intestine differentiated poorly and exhibited severely stunted villi. Transcriptome analysis revealed that YY1 is required for mitochondrial gene expression, and ultrastructural analysis confirmed compromised mitochondrial integrity in the mutant intestine. We found increased oxidative phosphorylation gene expression at the onset of villus elongation, suggesting that aerobic respiration might function as a regulator of villus growth. Mitochondrial inhibitors blocked villus growth in a fashion similar to Yy1 loss, thus further linking oxidative phosphorylation with late-gestation intestinal development. Interestingly, we find that necrotizing enterocolitis patients also exhibit decreased expression of oxidative phosphorylation genes. Our study highlights the still unappreciated role of metabolic regulation during organogenesis, and suggests that it might contribute to neonatal gastrointestinal disorders.

Positive feedback loop of hepatoma-derived growth factor and β-catenin promotes carcinogenesis of colorectal cancer

To clarify the role of hepatoma-derived growth factor (HDGF) and β-catenin in carcinogenesis of colorectal cancer (CRC), our results showed that high HDGF expression was found in CRC cells and tissues and significantly related to histological differentiation (p = 0.035) and lymph node metastasis (p = 0.000). Significant positive correlation between HDGF expression and β-catenin abnormal expression was found in CRC tissues. High HDGF and lymph node metastasis were the strong independent prognostic indicators for reduced overall survival in CRC patients. HDGF knockdown dramatically inhibited cellular proliferation, migration, invasion, and tumorigenesis, both in vitro and in vivo, but induced G1 phase arrest and apoptosis in CRC cells. HDGF knock-down dramatically suppressed β-catenin and its down-stream genes expression in CRC cells. Intriguingly, β-catenin knock-down dramatically suppressed HDGF expression in CRC cells. Human recombinant Wnt3a and DKK1 treatment increased and decreased HDGF, β-catenin, c-Myc, cyclin D1, MMP9, and phos-GSK-3β (Ser9) protein expression in nuclear and cytoplasmic fraction of CRC cells upon β-catenin knock-down, respectively. Three HDGF-binding elements in β-catenin promoter were found and specific for transcriptional activation of β-catenin in CRC cells. In conclusion, our results first suggest that HDGF and β-catenin interacts as a positive feedback loop, which plays an important role in carcinogenesis and progression of CRC.

Hepatoma derived growth factor (HDGF) dynamics in ovarian cancer cells

As a leading cause of cancer death among women, identification of pathophysiologically-relevant biomarkers for ovarian cancer is important. The heparin binding, hepatoma-derived growth factor (HDGF) is overexpressed in ovarian cancer cell lines and may have prognostic value, but the mechanism by which this predominantly nuclear protein is secreted or functions is unknown. In this study, we focused on the circumstances under which HDGF is released by cells and the functional relevance of extracellular HDGF in the context of ovarian cancer. Immunofluorescence imaging showed nuclear localization of HDGF in ovarian cells, but unlike what is reported for other cell types, HDGF was minimally secreted into the media. However, HDGF was passively released by necrotic and late apoptotic cells. Extracellular HDGF was functionally relevant as it stimulated phosphorylation of ERK 1/2 and P38 in both non-cancer and ovarian cancer cells, and enhanced cellular migration. Overall, our study uncovers a novel function of HDGF as a messenger of cellular condition (alarmin) which in-turn modulates cellular function-aspects that could be used as a biomarker for ovarian cancer.

A functional connectome: regulation of Wnt/TCF-dependent transcription by pairs of pathway activators

BACKGROUND

Wnt/β-catenin signaling is often portrayed as a simple pathway that is initiated by Wnt ligand at the cell surface leading, via linear series of interactions between 'core pathway' members, to the induction of nuclear transcription from genes flanked by β-catenin/TCF transcription factor binding sites. Wnt/β-catenin signaling is also regulated by a much larger set of 'non-core regulators'. However the relationship between 'non-core regulators' is currently not well understood. Aberrant activation of the pathway has been shown to drive tumorgenesis in a number of different tissues.

METHODS

Mammalian cells engineered to have a partially-active level of Wnt/β-catenin signaling were screened by transfection for proteins that up or down-regulated a mid-level of TCF-dependent transcription induced by transient expression of an activated LRP6 Wnt co-receptor (∆NLRP).

RESULTS

141 novel regulators of TCF-dependent transcription were identified. Surprisingly, when tested without ∆NLRP activation, most up-regulators failed to alter TCF-dependent transcription. However, when expressed in pairs, 27 % (466/1170) functionally interacted to alter levels of TCF-dependent transcription. When proteins were displayed as nodes connected by their ability to co-operate in the regulation of TCF-dependent transcription, a network of functional interactions was revealed. In this network, 'core pathway' components (Eg. β-catenin, GSK-3, Dsh) were found to be the most highly connected nodes. Activation of different nodes in this network impacted on the sensitivity to Wnt pathway small molecule antagonists.

CONCLUSIONS

The 'functional connectome' identified here strongly supports an alternative model of the Wnt pathway as a complex context-dependent network. The network further suggests that mutational activation of highly connected Wnt signaling nodes predisposed cells to further context-dependent alterations in levels of TCF-dependent transcription that may be important during tumor progression and treatment.

HDGF: a novel jack-of-all-trades in cancer

HDGF is an important regulator of a broad range of cancer cell activities and plays important roles in cancer cell transformation, apoptosis, angiogenesis and metastasis. Such a divergent influence of HDGF on cancer cell activities derives from its multiple inter- and sub-cellular localizations where it interacts with a range of different binding partners. Interestingly, high levels of HDGF could be detected in patients' serum of some cancers. This review is focused on the role of HDGF in tumorigenesis and metastasis, and provides insight for application in clinical cancer therapy as well as its clinical implications as a prognostic marker in cancer progression.

Hepatoma-Derived Growth Factor: Its Possible Involvement in the Progression of Hepatocellular Carcinoma

The development of hepatocellular carcinoma (HCC) is an important complication of viral infection induced by hepatitis virus C, and our major research theme is to identify a new growth factor related to the progression of HCC. HDGF (hepatoma-derived growth factor) is a novel growth factor that belongs to a new gene family. HDGF was initially purified from the conditioned medium of a hepatoma cell line. HDGF promotes cellular proliferation as a DNA binding nuclear factor and a secreted protein acting via a receptor-mediated pathway. HDGF is a unique multi-functional protein that can function as a growth factor, angiogenic factor and anti-apoptotic factor and it participates in the development and progression of various malignant diseases. The expression level of HDGF may be an independent prognostic factor for predicting the disease-free and overall survival in patients with various malignancies, including HCC. Furthermore, the overexpression of HDGF promotes the proliferation of HCC cells, while a reduction in the HDGF expression inhibits the proliferation of HCC cells. This article provides an overview of the characteristics of HDGF and describes the potential role of HDGF as a growth-promoting factor for HCC.

Genomic and transcriptomic analyses match medulloblastoma mouse models to their human counterparts

Medulloblastoma is a malignant embryonal brain tumor with highly variable outcome. In order to study the biology of this tumor and to perform preclinical treatment studies, a lot of effort has been put into the generation of appropriate mouse models. The usage of these models, however, has become debatable with the advances in human medulloblastoma subgrouping. This study brings together multiple relevant mouse models and matches genetic alterations and gene expression data of 140 murine tumors with 423 human medulloblastomas in a global way. Using AGDEX analysis and k-means clustering, we show that the Blbp-cre::Ctnnb1(ex3)(Fl/+)Trp53 (Fl/Fl) mouse model fits well to human WNT medulloblastoma, and that, among various Myc- or Mycn-based mouse medulloblastomas, tumors in Glt1-tTA::TRE-MYCN/Luc mice proved to be most specific for human group 3 medulloblastoma. None of the analyzed models displayed a significant match to group 4 tumors. Intriguingly, mice with Ptch1 or Smo mutations selectively modeled SHH medulloblastomas of adulthood, although such mutations occur in all human age groups. We therefore suggest that the infantile or adult gene expression pattern of SHH MBs are not solely determined by specific mutations. This is supported by the observation that human medulloblastomas with PTCH1 mutations displayed more similarities to PTCH1 wild-type tumors of the same age group than to PTCH1-mutated tumors of the other age group. Together, we provide novel insights into previously unrecognized specificity of distinct models and suggest these findings as a solid basis to choose the appropriate model for preclinical studies on medulloblastoma.

Depletion of hepatoma-derived growth factor-related protein-3 induces apoptotic sensitization of radioresistant A549 cells via reactive oxygen species-dependent p53 activation

Biomarkers based on functional signaling have the potential to provide greater insight into the pathogenesis of cancer and may offer additional targets for anticancer therapeutics. Here, we identified hepatoma-derived growth factor-related protein-3 (HRP-3) as a radioresistance-related gene and characterized the molecular mechanism by which its encoded protein regulates the radio- and chemoresistant phenotype of lung cancer-derived A549 cells. Knockdown of HRP-3 promoted apoptosis of A549 cells and potentiated the apoptosis-inducing action of radio- and chemotherapy. This increase in apoptosis was associated with a substantial generation of reactive oxygen species (ROS) that was attributable to inhibition of the Nrf2/HO-1 antioxidant pathway and resulted in enhanced ROS-dependent p53 activation and p53-dependent expression of PUMA (p53 upregulated modulator of apoptosis). Therefore, the HRP-3/Nrf2/HO-1/ROS/p53/PUMA cascade is an essential feature of the A549 cell phenotype and a potential radiotherapy target, extending the range of targets in multimodal therapies against lung cancer.

Anti-HDGF targets cancer and cancer stromal stem cells resistant to chemotherapy

PURPOSE

Approximately one third of the patients with advanced non-small cell lung carcinoma (NSCLC) will initially respond to platinum-based chemotherapy, but virtually all tumors will progress (acquired resistance). The remainder will progress during initial treatment (primary resistance). In this study, we test whether the treatment can be improved by inhibiting hepatoma-derived growth factor (HDGF).

EXPERIMENTAL DESIGN

Thirteen primary NSCLC heterotransplant models were used to test four treatment regimens, including platinum-based chemotherapy with and without bevacizumab (VEGF-neutralizing antibody) or HDGF-H3 (HDGF-neutralizing antibody) and chemotherapy with bevacizumab and HDGF-H3. Expression of stem cell-related genes was measured using quantitative reverse transcription PCR (qRT-PCR) and immunohistochemistry.

RESULTS

Among 13 primary NSCLC heterotransplant models, three (23%) responded to chemotherapy but all relapsed within 20 days. The residual tumors after response to the chemotherapy exhibited an increased expression in 51 (61%) of 84 genes related with stem cell proliferation and maintenance, particularly those in Notch and Wnt pathways, suggesting enrichment for stem cell populations in the residual tumors. Interestingly, tumors from two of three models treated with HDGF-H3, bevacizumab, and chemotherapy combination did not relapse during 6 months of posttreatment observation. Importantly, this treatment combination substantially downregulated expression levels in 57 (68%) of 84 stem cell-related genes, including 34 (67%) of 51 genes upregulated after the chemotherapy.

CONCLUSION

These data support the hypothesis that cancer stem cells (CSC) are a mechanism for chemotherapy resistance and suggest HDGF may be a target for repressing CSCs to prevent relapse of NSCLC sensitive to chemotherapy.

Hepatoma-derived growth factor and nucleolin exist in the same ribonucleoprotein complex

BACKGROUND

Hepatoma-derived growth factor (HDGF) is a protein which is highly expressed in a variety of tumours. HDGF has mitogenic, angiogenic, neurotrophic and antiapoptotic activity but the molecular mechanisms by which it exerts these activities are largely unknown nor has its biological function in tumours been elucidated. Mass spectrometry was performed to analyse the HDGFStrep-tag interactome. By Pull-down-experiments using different protein and nucleic acid constructs the interaction of HDGF and nucleolin was investigated further.

RESULTS

A number of HDGFStrep-tag copurifying proteins were identified which interact with RNA or are involved in the cellular DNA repair machinery. The most abundant protein, however, copurifying with HDGF in this approach was nucleolin. Therefore we focus on the characterization of the interaction of HDGF and nucleolin in this study. We show that expression of a cytosolic variant of HDGF causes a redistribution of nucleolin into the cytoplasm. Furthermore, formation of HDGF/nucleolin complexes depends on bcl-2 mRNA. Overexpression of full length bcl-2 mRNA increases the number of HDGF/nucleolin complexes whereas expression of only the bcl-2 coding sequence abolishes interaction completely. Further examination reveals that the coding sequence of bcl-2 mRNA together with either the 5' or 3' UTR is sufficient for formation of HDGF/nucleolin complexes. When bcl-2 coding sequence within the full length cDNA is replaced by a sequence coding for secretory alkaline phosphatase complex formation is not enhanced.

CONCLUSION

The results provide evidence for the existence of HDGF and nucleolin containing nucleoprotein complexes which formation depends on the presence of specific mRNAs. The nature of these RNAs and other components of the complexes should be investigated in future.

Differential proteomic analysis of human glioblastoma and neural stem cells reveals HDGF as a novel angiogenic secreted factor

Presence in glioblastomas of cancer cells with normal neural stem cell (NSC) properties, tumor initiating capacity, and resistance to current therapies suggests that glioblastoma stem-like cells (GSCs) play central roles in glioblastoma development. We cultured human GSCs endowed with all features of tumor stem cells, including tumor initiation after xenograft and radio-chemoresistance. We established proteomes from four GSC cultures and their corresponding whole tumor tissues (TTs) and from human NSCs. Two-dimensional difference gel electrophoresis and tandem mass spectrometry revealed a twofold increase of hepatoma-derived growth factor (HDGF) in GSCs as compared to TTs and NSCs. Western blot analysis confirmed HDGF overexpression in GSCs as well as its presence in GSC-conditioned medium, while, in contrast, no HDGF was detected in NSC secretome. At the functional level, GSC-conditioned medium induced migration of human cerebral endothelial cells that can be blocked by anti-HDGF antibodies. In vivo, GSC-conditioned medium induced neoangiogenesis, whereas HDGF-targeting siRNAs abrogated this effect. Altogether, our results identify a novel candidate, by which GSCs can support neoangiogenesis, a high-grade glioma hallmark. Our strategy illustrates the usefulness of comparative proteomic analysis to decipher molecular pathways, which underlie GSC properties.

The expression and prognostic significance of hepatoma-derived growth factor in oral cancer

Hepatoma-derived growth factor (HDGF) participates in oncogenic progression and represents a prognostic factor in several types of cancer. This study aimed to elucidate the role of HDGF during oral carcinogenesis. HDGF expression and the tumorigenic behaviors in human oral cell lines were investigated by immunoblotting, invasion and colony formation assays. Recombinant adenovirus vectors were employed to modulate the HDGF level in oral cancer cells. Immunohistochemical analysis using tissue microarray (TMA) consisting of surgically resected samples from 95 oral cancer patients was performed to delineate the correlation between HDGF expression and clinic-pathological parameters. HDGF expression was higher in malignant oral cancer cells than benign ones. Adenovirus-mediated HDGF overexpression and knockdown demonstrated the cellular HDGF level regulated the tumorigenic behaviors of oral cancer cells. Immunohistochemical analysis revealed increased HDGF expression in the nucleus and cytoplasm in oral cancer tissues. The nuclear HDGF expression was significantly correlated with tumor stage (P=0.004) and grade (P=0.013) while the cytoplasmic HDGF expression was associated with tumor necrosis (P=0.002). Kaplan-Meier analysis revealed that patients with high nuclear HDGF expression had significantly worse 5-year disease-specific survival (P=0.0069), metastasis-free survival (P=0.0168), and local recurrence-free survival (P=0.0047). Multivariate analysis indicated that the nuclear HDGF labeling index was an independent prognostic factor for disease-specific and local recurrence-free survival. HDGF overexpression contributes to the oncogenic processes in oral cancer cells and constitutes a novel prognostic factor for survival outcome of oral cancer patients.

A proline rich acidic protein PRAP identified from uterine luminal fluid of estrous mice is able to enhance the estrogen responsiveness of Ishikawa cells

Using mice as experimental animals, proteins in the uterine luminal fluid (ULF) from both adults and diethylstilbestrol dipropionate (DES)-treated immature animals were resolved by 2D gel electrophoresis. Two of the protein spots, (a) and (b) around the positions of 18-20 kDa, in the adult ULF were not found in the DES-treated ULF. Automated Edman degradation established the same N-terminal sequences of AHQVPVKTKGKHVFP for the two protein spots. Two trypsin digests of spot (a) were analyzed using CID MS/MS to establish the peptide sequences DNQLGPLLPEPK and RPDAMTWVETEDILSHLR. These partial sequences were confirmed in the cDNA-deduced mouse proline rich acidic protein (PRAP). Using human Ishikawa cell line as a surrogate endometrial model, we demonstrated rapid entrance of exogenous PRAP into the cells and its ability to enhance alkaline phosphatase activity of the E(2) -stimulated cells. Further, the transcripts of five estrogen-responsive genes, including ALPP (Placental alkaline phosphtase), ALPPL (placental alkaline phosphatase-like 2), TGF (transforming growth factor), PR (progesterone receptor), and Wnt7a, were measured after the cell incubation in modified Eagle medium containing 0.1 nM E(2) , or 0-25 µM PRAP, or both together at 37°C for 48 h. As compared with the control, E(2) alone increased the transcripts of ALPP, ALPPL, TGF-α, and PR, and reduced the transcript of Wnt7a, whereas PRAP alone had a slight impact on their expression. E(2) together with PRAP greatly increased the E(2) -stimulated transcriptions of ALPP, ALPPL, TGF-α, and PR, and markedly reduced the E(2) -suppressed transcription of Wnt7a.

Lessons from in vitro studies and a related intracellular angiotensin II transgenic mouse model

In the classical renin-angiotensin system, circulating ANG II mediates growth stimulatory and hemodynamic effects through the plasma membrane ANG II type I receptor, AT1. ANG II also exists in the intracellular space in some native cells, and tissues and can be upregulated in diseases, including hypertension and diabetes. Moreover, intracellular AT1 receptors can be found associated with endosomes, nuclei, and mitochondria. Intracellular ANG II can function in a canonical fashion through the native receptor and also in a noncanonical fashion through interaction with alternative proteins. Likewise, the receptor and proteolytic fragments of the receptor can function independently of ANG II. Participation of the receptor and ligand in alternative intracellular pathways may serve to amplify events that are initiated at the plasma membrane. We review historical and current literature relevant to ANG II, compared with other intracrines, in tissue culture and transgenic models. In particular, we describe a new transgenic mouse model, which demonstrates that intracellular ANG II is linked to high blood pressure. Appreciation of the diverse, pleiotropic intracellular effects of components of the renin-angiotensin system should lead to alternative disease treatment targets and new therapies.

Tumorigenesis and prognostic role of hepatoma-derived growth factor in human gliomas

Hepatoma-derived growth factor (HDGF) is a neurotrophic factor found in mouse spinal cord and hippocampal neurons. In various malignant tumors, the role of HDGF in tumor progression and its use as a diagnostic biomarker or therapeutic target have been extensively explored. However, the prognostic function and mitogenic role of HDGF in gliomagenesis are yet to be verified. In this study, we found a significant incidence of HDGF prevalence between the different pathological types and stages of glioma in 105 patients. We also found a prognostic significance in 41 glioblastoma multiforme (GBM) patients, with prevalence of nuclear HDGF predicting short survival of patients with GBM after surgery. To delineate the mitogenic role of HDGF in gliomagenesis, an adenoviral-expressed HDGF small interfering RNA (Ad-HDGF siRNA) was used to knock down expression of nuclear HDGF. After knocking down nuclear HDGF expression in human GBM cells, cell growth and cell invasion and induction on apoptosis by caspase-3 activation were significantly inhibited. We conclude that HDGF is a mitogenic growth factor in glioma progression and can be a useful prognostic marker for GBM and therapeutic target for clinical management of glioma in the future.

Overexpression of hepatoma-derived growth factor in melanocytes does not lead to oncogenic transformation

BACKGROUND

HDGF is a growth factor which is overexpressed in a wide range of tumors. Importantly, expression levels were identified as a prognostic marker in some types of cancer such as melanoma.

METHODS

To investigate the presumed oncogenic/transforming capacity of HDGF, we generated transgenic mice overexpressing HDGF in melanocytes. These mice were bred with mice heterozygous for a defective copy of the Ink4a tumor suppressor gene and were exposed to UV light to increase the risk for tumor development both genetically and physiochemically. Mice were analyzed by immunohistochemistry and Western blotting. Furthermore, primary melanocytes were isolated from different strains created.

RESULTS

Transgenic animals overexpressed HDGF in hair follicle melanocytes. Interestingly, primary melanocytes isolated from transgenic animals were not able to differentiate in vitro whereas cells isolated from wild type and HDGF-deficient animals were. Although, HDGF-/-/Ink4a+/- mice displayed an increased number of epidermoid cysts after exposure to UV light, no melanomas or premelanocytic alterations could be detected in this mouse model.

CONCLUSIONS

The results therefore provide no evidence that HDGF has a transforming capacity in tumor development. Our results in combination with previous findings point to a possible role in cell differentiation and suggest that HDGF promotes tumor progression after secondary upregulation and may represent another protein fitting into the concept of non-oncogene addiction of tumor tissue.

p53 negatively regulates the hepatoma growth factor HDGF

Hepatoma-derived growth factor (HDGF) is a secreted heparin-binding growth factor that has been implicated in cancer development and progression. Here, we report that HDGF is a critical target for transcriptional repression by the tumor suppressor p53. Endogenous HDGF expression was decreased in cancer cells with introduction of wild-type p53, which also downregulated HDGF expression after DNA damage. In support of the likelihood that HDGF is a critical driver of cancer cell growth, addition of neutralizing HDGF antibodies to culture media was sufficient to block cell growth, migration, and invasion. Similarly, these effects were elicited by conditioned culture medium from p53-expressing cells, and they could be reversed by the addition of recombinant human HDGF. Interestingly, we found that HDGF was overexpressed also in primary gastric, breast, and lung cancer tissues harboring mutant p53 genes. Mechanistic investigations revealed that p53 repressed HDGF transcription by altering HDAC-dependent chromatin remodeling. Taken together, our results reveal a new pathway in which loss of p53 function contributes to the aggressive pathobiological potential of human cancers by elevating HDGF expression.

Structural and histone binding ability characterizations of human PWWP domains

BACKGROUND

The PWWP domain was first identified as a structural motif of 100-130 amino acids in the WHSC1 protein and predicted to be a protein-protein interaction domain. It belongs to the Tudor domain 'Royal Family', which consists of Tudor, chromodomain, MBT and PWWP domains. While Tudor, chromodomain and MBT domains have long been known to bind methylated histones, PWWP was shown to exhibit histone binding ability only until recently.

METHODOLOGY/PRINCIPAL FINDINGS

The PWWP domain has been shown to be a DNA binding domain, but sequence analysis and previous structural studies show that the PWWP domain exhibits significant similarity to other 'Royal Family' members, implying that the PWWP domain has the potential to bind histones. In order to further explore the function of the PWWP domain, we used the protein family approach to determine the crystal structures of the PWWP domains from seven different human proteins. Our fluorescence polarization binding studies show that PWWP domains have weak histone binding ability, which is also confirmed by our NMR titration experiments. Furthermore, we determined the crystal structures of the BRPF1 PWWP domain in complex with H3K36me3, and HDGF2 PWWP domain in complex with H3K79me3 and H4K20me3.

CONCLUSIONS

PWWP proteins constitute a new family of methyl lysine histone binders. The PWWP domain consists of three motifs: a canonical β-barrel core, an insertion motif between the second and third β-strands and a C-terminal α-helix bundle. Both the canonical β-barrel core and the insertion motif are directly involved in histone binding. The PWWP domain has been previously shown to be a DNA binding domain. Therefore, the PWWP domain exhibits dual functions: binding both DNA and methyllysine histones.

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Vertebrate intestinal endoderm development

The endoderm gives rise to the lining of the esophagus, stomach and intestines, as well as associated organs. To generate a functional intestine, a series of highly orchestrated developmental processes must occur. In this review, we attempt to cover major events during intestinal development from gastrulation to birth, including endoderm formation, gut tube growth and patterning, intestinal morphogenesis, epithelial reorganization, villus emergence, as well as proliferation and cytodifferentiation. Our discussion includes morphological and anatomical changes during intestinal development as well as molecular mechanisms regulating these processes.

Estimating developmental states of tumors and normal tissues using a linear time-ordered model

Background

Tumor cells are considered to have an aberrant cell state, and some evidence indicates different development states appearing in the tumorigenesis. Embryonic development and stem cell differentiation are ordered processes in which the sequence of events over time is highly conserved. The "cancer attractor" concept integrates normal developmental processes and tumorigenesis into a high-dimensional "cell state space", and provides a reasonable explanation of the relationship between these two biological processes from theoretical viewpoint. However, it is hard to describe such relationship by using existed experimental data; moreover, the measurement of different development states is also difficult.

Results

Here, by applying a novel time-ordered linear model based on a co-bisector which represents the joint direction of a series of vectors, we described the trajectories of development process by a line and showed different developmental states of tumor cells from developmental timescale perspective in a cell state space. This model was used to transform time-course developmental expression profiles of human ESCs, normal mouse liver, ovary and lung tissue into "cell developmental state lines". Then these cell state lines were applied to observe the developmental states of different tumors and their corresponding normal samples. Mouse liver and ovarian tumors showed different similarity to early development stage. Similarly, human glioma cells and ovarian tumors became developmentally "younger".

Conclusions

The time-ordered linear model captured linear projected development trajectories in a cell state space. Meanwhile it also reflected the change tendency of gene expression over time from the developmental timescale perspective, and our finding indicated different development states during tumorigenesis processes in different tissues.

Cell surface heparan sulfates mediate internalization of the PWWP/HATH domain of HDGF via macropinocytosis to fine-tune cell signalling processes involved in fibroblast cell migration

HDGF (hepatoma-derived growth factor) stimulates cell proliferation by functioning on both sides of the plasma membrane as a ligand for membrane receptor binding to trigger cell signalling and as a stimulator for DNA synthesis in the nucleus. Although HDGF was initially identified as a secretory heparin-binding protein, the biological significance of its heparin-binding ability remains to be determined. In the present study we demonstrate that cells devoid of surface HS (heparan sulfate) were unable to internalize HDGF, HATH (N-terminal domain of HDGF consisting of amino acid residues 1-100, including the PWWP motif) and HATH(K96A) (single-site mutant form of HATH devoid of receptor binding activity), suggesting that the binding of HATH to surface HS is important for HDGF internalization. We further demonstrate that both HATH and HATH(K96A) could be internalized through macropinocytosis after binding to the cell surface HS. Interestingly, HS-mediated HATH(K96A) internalization is found to exhibit an inhibitory effect on cell migration and proliferation in contrast with that observed for HATH action on NIH 3T3 cells, suggesting that HDGF exploits the innate properties of both cell surface HS and membrane receptor via the HATH domain to affect related cell signalling processes. The present study indicates that MAPK (mitogen-activated protein kinase) signalling pathways could be affected by the HS-mediated HATH internalization to regulate cell migration in NIH 3T3 fibroblasts, as judged from the differential effect of HATH and HATH(K96A) treatment on the expression level of matrix metalloproteases.

Increased expression of hepatoma-derived growth factor correlates with poor prognosis in human nasopharyngeal carcinoma

AIMS

To examine the correlation between hepatoma-derived growth factor (HDGF) expression and clinicopathological data in nasopharyngeal carcinoma (NPC), including patient survival.

METHODS AND RESULTS

Using real-time polymerase chain reaction (PCR) and Western blot, mRNA and protein expression of HDGF was detected in normal nasopharyngeal tissues, NPC tissues and cell lines. HDGF levels were determined further by an immunohistochemical analysis in a retrospective series consisting of 160 primary NPC tissues and 71 non-cancerous nasopharynx tissues. Overexpressed mRNA and HDGF protein was present in NPC. By immunohistochemical analysis, we found that 53.8% (86 of 160) and 19.4% (32 of 160) of NPC biopsy specimens showed higher HDGF expression of the nucleus and cytoplasm, respectively. Statistical analysis showed that the higher expression of nuclear HDGF was associated significantly with T stage (P=0.005) and clinical stage (P=0.038), but there was no association with lymph node (P=0.059) or distant metastasis (P=0.563). Patients with increased HDGF expression levels had poorer overall survival rates than those with low expression of HDGF levels (P=0.006). Multivariate analysis revealed that high expression of nuclear HDGF was an independent prognostic indicator of patient survival.

CONCLUSIONS

Increased nuclear expression of HDGF is a potential unfavourable prognostic factor for patients with NPC.

Uterine luminal epithelium-specific proline-rich acidic protein 1 (PRAP1) as a marker for successful embryo implantation

Proline-rich acidic protein 1 mRNA is highly expressed in the uterine luminal epithelium (LE) of day 0.5 mouse uterus, disappears in the preimplantation day 3.5 uterus, and reappears abundantly in the LE after embryo implantation has occurred or upon artificial decidualization. In ovariectomized uterus, Prap1 is down-regulated by P, transiently down-regulated by E(2) treatment for 6 hours, but dramatically induced by E(2) treatment for 3 days.

Apoptosis of human colorectal carcinoma cells is induced by blocking hepatoma-derived growth factor

Hepatoma-derived growth factor (HDGF) is a novel multifunctional growth factor that elicits pleiotropic effects on biological processes such as lung remodeling and renal development. Recent studies demonstrated that HDGF is related to tumor proliferation, invasion, angiogenesis, and apoptosis. However, the molecular mechanism of HDGF's involvement in apoptosis remains to be clarified. In this study, we first analyze the role of HDGF in colorectal carcinoma (CRC) progression by immunohistochemistry. Then we used small interference RNA (HDGF-siRNA) to block HDGF and assessed its effect on inducing apoptosis of CRC loVo cells. Apoptosis was detected using flow cytometry (FCM), DNA ladder analysis, and Hoechst 33258 staining. In addition, the expression levels of some apoptosis-related proteins were examined by western blot. The result showed that HDGF expression gradually increased in the colorectal carcinogenesis process. Further studies demonstrated that knock-down of HDGF can down-regulate the survivin, activate the mitochondrial pathway, and induce apoptosis in loVo cells. These findings suggest that HDGF is involved in colorectal carcinogenesis process. Further blocking HDGF exhibits potent pro-apoptotic properties in colon cancer cells. Thus, HDGF might be a potential therapeutic target for human colorectal cancer. These findings may have major implications in the treatment of colorectal cancer.

Partial blockage of hepatocyte maturation in hepatoma-derived growth factor transgenic mice

AIM

To investigate the role of hepatoma-derived growth factor (HDGF) in liver development, especially in the hepatocyte differentiation.

METHODS

We generated transgenic mice which overexpressed HDGF in hepatocytes under the transcriptional control of mouse albumin promoter/enhancer. To examine the effects of HDGF overexpression on hepatocyte differentiation, we investigated the expression patterns of the differentiation marker genes.

RESULTS

The HDGF transgenic mice developed normally and showed no apparent abnormality in the liver. However, the gene expression patterns of the liver in adult transgenic mice were similar to those of the neonatal liver in control mice.

CONCLUSION

These findings suggest that HDGF-overexpression partially suppresses hepatocyte maturation.

FACS-assisted microarray profiling implicates novel genes and pathways in zebrafish gastrointestinal tract development

BACKGROUND & AIMS

The zebrafish Danio rerio is an excellent model system for mammalian gastrointestinal development. To identify differentially regulated genes important in gastrointestinal organogenesis, we profiled the transcriptome of the zebrafish developing gastrointestinal tract.

METHODS

Embryos from a transgenic zebrafish line expressing green fluorescent protein (GFP) in the developing intestine, liver, and pancreas were dissociated at 4 developmental time points, their cells sorted based on GFP expression with fluorescence-activated cell sorting (FACS), and analyzed with microarrays. To improve our analysis, we annotated the Affymetrix Zebrafish GeneChip with human orthologs.

RESULTS

Transcriptional profiling showed significant differences between GFP(+) and GFP(-) cells. Up-regulated genes and pathways were consistent with mammalian gastrointestinal development, such as hepatic nuclear factor gene networks and cancer. We implicate the phosphatidylinositol 3 kinase (PI3K) pathway and show that inhibition with LY294002 causes gastrointestinal defects in zebrafish. We identified novel genes, such as the microRNAs miR-217 and miR-122, the tight junction protein claudin c, the gene fam136a, and a zebrafish tetraspanin. Novel pathways include genes containing a putative transcription factor binding sequence, GGAANCGGAANY, and a nucleolar gene network. The zebrafish microarrays also identify a set of 32 genes that may mediate the effects of gain of chromosome arm 8q in human colon, liver, and pancreatic cancers.

CONCLUSIONS

We successfully combine FACS and microarray profiling to follow organogenesis throughout development. These experiments identify novel genes and pathways that probably play a role in mammalian gastrointestinal development and are potential targets for therapeutic intervention in the management of gastrointestinal disease and cancer.

Hepatoma-derived growth factor and its role in keloid pathogenesis

Hepatoma-derived growth factor (HDGF) is a novel mitogenic growth factor that has been implicated in many different carcinomas. Its role in keloid biology has not yet been investigated. The present study is aimed at examining the role of HDGF in keloid pathogenesis. Immunohistochemical staining and Western blot analyses were used to examine in vivo localization and expression of HDGF in keloid and normal skin tissue. This was followed by the detection of HDGF expression in fibroblasts cultured in vitro and fibroblasts exposed to serum. To investigate the effect of epithelial–mesenchymal interactions, a two-chamber system was employed in which keratinocytes on membrane inserts were co-cultured with the fibroblasts. HDGF expression levels in all cell extracts and conditioned media were assayed through Western blot analysis. In another set of experiments, the effect of exogenous recombinant HDGF on keloid fibroblasts (KF) and normal fibroblasts (NF) was examined. Cell proliferation was assessed by the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay and by quantifying proliferating cell nuclear antigen (PCNA) expression. Downstream targets of HDGF were identified by detecting their expression through Western blot analysis. Our results indicate that there was an increase in HDGF expression in the dermis of keloid compared with normal skin tissue. The application of serum and epithelial–mesenchymal interactions did not seem to have any effect on intracellular HDGF expression levels. However, co-culturing keloid keratinocytes with KFs resulted in increased HDGF secretion when compared with monoculture or normal controls. Furthermore, treatment with exogenous recombinant HDGF was found to increase the proliferation of KFs, activate the extracellular signal-regulated kinase (ERK) pathway and up-regulate the secretion of vascular endothelial growth factor (VEGF).