Erk and MAPK signaling is essential for intestinal development through Wnt pathway modulation.

Homeostasis of intestinal stem cells (ISCs) is maintained by the orchestration of niche factors and intrinsic signaling networks. Here, we have found that deletion of Erk1 and Erk2 (Erk1/2) in intestinal epithelial cells at embryonic stages resulted in an unexpected increase in cell proliferation and migration, expansion of ISCs, and formation of polyp-like structures, leading to postnatal death. Deficiency of epithelial Erk1/2 results in defects in secretory cell differentiation as well as impaired mesenchymal cell proliferation and maturation. Deletion of Erk1/2 strongly activated Wnt signaling through both cell-autonomous and non-autonomous mechanisms. In epithelial cells, Erk1/2 depletion resulted in loss of feedback regulation, leading to Ras/Raf cascade activation that transactivated Akt activity to stimulate the mTor and Wnt/ß-catenin pathways. Moreover, Erk1/2 deficiency reduced the levels of Indian hedgehog and the expression of downstream pathway components, including mesenchymal Bmp4 - a Wnt suppressor in intestines. Inhibition of mTor signaling by rapamycin partially rescued Erk1/2 depletion-induced intestinal defects and significantly prolonged the lifespan of mutant mice. These data demonstrate that Erk/Mapk signaling functions as a key modulator of Wnt signaling through coordination of epithelial-mesenchymal interactions during intestinal development.

GPR126 regulates colorectal cancer cell proliferation by mediating HDAC2 and GLI2 expression.

The G-protein-coupled receptor 126 (GPR126) may play an important role in tumor development, although its role remains poorly understood. We found that GPR126 had higher expression in most colorectal cancer cell lines than in normal colon epithelial cell lines, and higher expression levels in colorectal cancer tissues than in normal adjacent colon tissues. GPR126 knockdown induced by shRNA inhibited cell viability and colony formation in HT-29, HCT116, and LoVo cells, decreased BrdU incorporation into newly synthesized proliferating HT-29 cells, led to an arrest of cell cycle progression at the G1 phase in HCT-116 and HT-29 cells, and suppressed tumorigenesis of HT-29, HCT116, and LoVo cells in nude mouse xenograft models. GPR126 knockdown engendered decreased transcription and translation of histone deacetylase 2 (HDAC2), previously implicated in the activation of GLI1 and GLI2 in the Hedgehog signaling pathway. Ectopic expression of HDAC2 in GPR126-silenced cells restored cell viability and proliferation, GLI2 luciferase reporter activity, partially recovered GLI2 expression, and reduced the cell cycle arrest. HDAC2 regulated GLI2 expression and, along with GLI2, it bound to the PTCH1 promoter, as evidenced by a chip assay with HT-29 cells. Purmorphamine, a hedgehog agonist, largely restored the cell viability and expression of GLI2 proteins in GPR126-silenced HT-29 cells, whereas GANT61, a hedgehog inhibitor, further enhanced the GPR126 knockdown-induced inhibitory effects. Our findings demonstrate that GPR126 regulates colorectal cancer cell proliferation by mediating the expression of HDAC2 and GLI2, therefore it may represent a suitable therapeutic target for colorectal cancer treatment.

Epithelial Wntless is dispensable for intestinal tumorigenesis in mouse models.

Wnt signaling is essential for the maintenance of adult stem cells and its aberrant activation is a stimulator of carcinogenesis. The transmembrane protein, Wntless, is an essential Wnt signaling component through regulating the secretion of Wnt ligands. Here, we generated a mouse model with specific Wntless knockout in intestinal epithelium to study its function in the intestinal epithelium. Wntless knockout exhibits no obvious defects in mice but significantly disrupted proliferation and differentiation of small intestinal organoids. We also discovered that these deficiencies could be partially rescued by Wnt3a supplement but not Wnt9b. To further investigate the role of Wntless in tumorigenesis, APC-deficient spontaneous intestinal tumors and chemical induced colorectal cancer mouse models were employed. To our surprise, intestinal epithelium-specific knockout of Wntless did not cause significant differences in tumor number and size. In summary, our data demonstrated that epithelial Wntless was required for the growth and differentiation of small intestinal organoids but not in live animals, suggesting the other tissues, such as mesenchymal tissue, play critical role for Wnt secretion in both intestinal homeostasis as well as tumorigenesis.

MiR-539 functions as a tumor suppressor in pancreatic cancer by targeting TWIST1.

The dysregulation of microRNA (miRNA) expression has been highlighted in a variety of human malignant conditions with reports implicating a critical role in the process of tumor growth. The role of miR-539 in pancreatic cancer (PC) is yet to be fully elucidated, hence the aim of the current study was to investigate the effect of miR-539 expression in relation to a cohort of 52 PC specimens. The application of a real-time quantitative polymerase chain reaction (qRT-PCR) revealed a significantly down-regulated miR-539 level, which was accompanied by an increased TWIST1 expression in PC when compared with the controls. The in vitro experiment results demonstrated that the endogenic mimic of miR-539 significantly suppressed the growth of the xenograft tumors in PANC-1 cells, when compared to the delivery of the control miRNA and blank control. Meanwhile, the key epithelial-mesenchymal transition (EMT) inducer, TWIST1 was verified as a direct target gene of miR-539 through the application of a luciferase reporter assay. In conclusion, the results of the current study present evidence emphasizing the significance of the interactions between miR-539 and TWIST1 in the development of and progression of PC, highlighting its potential as a therapeutic target in the treatment of PC patients.

Elevation of GPRC5A expression in colorectal cancer promotes tumor progression through VNN-1 induced oxidative stress.

The clearance of oxidative stress compounds is critical for the protection of the organism from malignancy, but how this key physiological process is regulated is not fully understood. Here, we found that the expression of GPRC5A, a well-characterized tumor suppressor in lung cancer, was elevated in colorectal cancer tissues in patients. In both cancer cell lines and a colitis-associated cancer model in mice, we found that GPRC5A deficiency reduced cell proliferation and increased cell apoptosis as well as inhibited tumorigenesis in vivo. Through RNA-Seq transcriptome analysis, we identified oxidative stress associated pathways were dysregulated. Moreover, in GPRC5A deficient cells and mouse tissues, the oxidative agents were reduced partially due to increased glutathione (GSH) level. Mechanistically, GPRC5A regulates NF-κB mediated Vanin-1 expression which is the predominant enzyme for cysteamine generation. Administration of cystamine (the disulfide form of cysteamine) in GPRC5A deficient cell lines inhibited γ-GCS activity, leading to reduction of GSH level and increase of cell growth. Taken together, our studies suggest that GPRC5a is a potential biomarker for colon cancer and promotes tumorigenesis through stimulation of Vanin-1 expression and oxidative stress in colitis associated cancer. This study revealed an unexpected oncogenic role of GPRC5A in colorectal cancer suggesting there are complicated functional and molecular mechanism differences of this gene in distinct tissues.

Repression of Mammalian Target of Rapamycin Complex 1 Inhibits Intestinal Regeneration in Acute Inflammatory Bowel Disease Models.

The mammalian target of rapamycin (mTOR) signaling pathway integrates environmental cues to regulate cell growth and survival through various mechanisms. However, how mTORC1 responds to acute inflammatory signals to regulate bowel regeneration is still obscure. In this study, we investigated the role of mTORC1 in acute inflammatory bowel disease. Inhibition of mTORC1 activity by rapamycin treatment or haploinsufficiency of Rheb through genetic modification in mice impaired intestinal cell proliferation and induced cell apoptosis, leading to high mortality in dextran sodium sulfate- and 2,4,6-trinitrobenzene sulfonic acid-induced colitis models. Through bone marrow transplantation, we found that mTORC1 in nonhematopoietic cells played a major role in protecting mice from colitis. Reactivation of mTORC1 activity by amino acids had a positive therapeutic effect in mTORC1-deficient Rheb(+/-) mice. Mechanistically, mTORC1 mediated IL-6-induced Stat3 activation in intestinal epithelial cells to stimulate the expression of downstream targets essential for cell proliferation and tissue regeneration. Therefore, mTORC1 signaling critically protects against inflammatory bowel disease through modulation of inflammation-induced Stat3 activity. As mTORC1 is an important therapeutic target for multiple diseases, our findings will have important implications for the clinical usage of mTORC1 inhibitors in patients with acute inflammatory bowel disease.

SGT1 regulates Akt signaling by promoting beta-TrCP-dependent PHLPP1 degradation in gastric cancer cells.

SGT1 (suppressor of G2 allele of Skp1) plays a role in various cellular processes including kinetochore assembly and protein ubiquitination by interacting with Skp1, a component of SCF E3 ligase complex. However, the function of SGT1 in cancer is largely unknown. Here, we showed that SGT1 was over-expressed in gastric cancer tissues and silencing of SGT1 by siRNAs significantly inhibited the growth and colony formation of gastric cancer cells. We further showed that SGT1 could regulate Akt signaling pathway by modulating Akt ser473 phosphorylation status. Moreover, we found that SGT1 was able to regulate the stability of PHLPP1, which is the direct phosphatase for Akt ser473 phosphorylation. Immunoprecipitation assay revealed that SGT1 could enhance the binding between PHLPP1 and beta-TrCP which has been documented to be able to target PHLPP1 for destruction. Decreased PHLPP1 in SGT1 over-expressed gastric cancer cells failed to dephosphorylate Akt and resulted in increased Akt ser473 phosphorylation and amplified downstream Akt signaling. Thus, our data revealed a previously uncovered role of SGT1 in gastric cancer development, and suggested that SGT1 could be a promising anti-cancer target to against gastric cancer.

The association of polymorphisms on TGFBR1 and colorectal cancer risk: a meta-analysis.

Epidemiological studies found inconsistent results on the association of two variants on TGFBR1 (TGFBR1*6A and Int7G24A) with colorectal cancer (CRC) risk. The present study was aimed to evaluate the association of these two variants with CRC susceptibility via the meta-analysis methods. For variant TGFBR1*6A, nine reports including 6,765 CRC patients and 8,496 unrelated controls were identified. The heterozygotes *6A/*9A showed a significant increased risk of CRC with the pooled OR was 1.12 (95% CI = 1.02-1.23), and the pooled OR for the homozygotes *6A/*6A was 1.13 (95% CI = 0.80-1.58) compared to the homozygotes *9A/*9A. However, under the dominant effect model, the TGFBR1*6A carriers showed a significantly increased CRC risk (pooled OR = 1.12, 95% CI = 1.03-1.23, *6A/*6A and *6A/*9A vs. *9A/*9A). For variant Int7G24A, three case-control studies with 1,074 cases and 1,945 controls were found. Although no significant association was found for heterozygosity Int7G24A carriers with CRC risk (pooled OR = 0.97, 95% CI = 0.67-1.42), the homozygosity A/A carriers showed a significant elevated risk of CRC (pooled OR = 1.68, 95% CI = 1.14-2.47) compared to G/G homozygotes. Under the recessive effect model, homozygotes A/A showed a 71% increase of CRC risk compared to the A/G and G/G genotype carriers (pooled OR = 1.71, 95% CI = 1.17-2.51). These data strongly suggested that the two polymorphisms of TGFBR1 may confer low-penetrance susceptibility of CRC risk.

Identification and validation of a novel angiogenesis-related gene signature for predicting prognosis in gastric adenocarcinoma.

Background: Angiogenesis is a major promotor of tumor progression and metastasis in gastric adenocarcinoma (STAD). We aimed to develop a novel lncRNA gene signature by identifying angiogenesis-related genes to better predict prognosis in STAD patients. Methods: The expression profiles of angiogenesis-related mRNA and lncRNA genes were collected from The Cancer Genome Atlas (TCGA). Then, the "limma" package was used to identify differentially expressed genes (DEGs). The expression profiles of angiogenesis-related genes were clustered by consumusclusterplus. The Pearson correlation coefficient was further used to identify lncRNAs coexpressed with angiogenesis-related clustere genes. We used Lasso Cox regression analysis to construct the angiogenesis-related lncRNAs signature. Furthermore, the diagnostic accuracy of the prognostic risk signature were validated by the TCGA training set, internal test sets and external test set. We used multifactor Cox analysis to determine that the risk score is an independent prognostic factor different from clinical characteristics. Nomogram has been used to quantitatively determine personal risk in a clinical environment. The ssGSEA method or GSE176307 data were used to evaluate the infiltration state of immune cells or predictive ability for the benefit of immunotherapy by angiogenesis-related lncRNAs signature. Finally, the expression and function of these signature genes were explored by RT-PCR and colony formation assays. Results: Among angiogenesis-related genes clusters, the stable number of clusters was 2. A total of 289 DEGs were identified and 116 lncRNAs were screened to have a significant coexpression relationship with angiogenic DEGs (P value<0.001 and |R| >0.5). A six-gene signature comprising LINC01579, LINC01094, RP11.497E19.1, AC093850.2, RP11.613D13.8, and RP11.384P7.7 was constructed by Lasso Cox regression analysis. The multifactor Cox analysis and Nomogram results showed that our angiogenesis-related lncRNAs signature has good predictive ability for some different clinical factors. For immune, angiogenesis-related lncRNAs signature had the ability to efficiently predict infiltration state of 23 immune cells and immunotherapy. The qPCR analysis showed that the expression levels of the six lncRNA signature genes were all higher in gastric adenocarcinoma tissues than in adjacent tissues. The functional experiment results indicated that downregulation of the expression of these six lncRNA signature genes suppressed the proliferation of ASG and MKN45 cells. Conclusion: Six angiogenesis-related genes were identified and integrated into a novel risk signature that can effectively assess prognosis and provide potential therapeutic targets for STAD patients.

Effects of Roux-en-Y operations on glucose homeostasis in obese GK rats.

AIM: To investigate the therapeutic effects of different styles of gastric bypass surgery on type 2 diabetes mellitus (T2DM) GK rats. METHODS: Twenty 6-8-week-old male GK rats were randomly divided into four groups: group A was operated by Roux-en-Y gastrojejunostomy with duodenum exclusion and stomach capacity maintenance, group B was operated by loop-type gastrojejunostomy with duodenum exclusion and stomach capacity maintenance, group C was operated by Roux-en-Y gastrojejunostomy with partial gastrectomy, and group D was operated by loop-type gastrojejunostomy with partial gastrectomy. Changes of fasting blood glucose, oral glucose tolerance test (OGTT), and insulin tolerance test (ITT) in different operations were detected. RESULTS: The operations exerted good effects on controlling blood glucose in groups A, B, C, and D. There was no significant difference between groups A and C (P > 0.05) or between groups B and D (P > 0.05), while operations in groups A and C were more effective than groups B and D (P < 0.05). On the 21st day after surgery, OGTT in animals of groups A and C was significantly improved, as indicated by a 34% reduction in the area under the curve (AUC) for blood glucose (P < 0.05 versus groups B and D); pregavage insulin levels (ng/ml) were significantly decreased in groups A and C (P < 0.05 versus groups B and D). The insulin tolerance test (ITT) confirmed impaired insulin sensitivity in groups B and D, compared with groups A and C. CONCLUSIONS: Gastric bypass surgery might be effective to treat type 2 diabetes mellitus (T2DM), and Roux-en-Y gastrojejunostomy might be more effective than other operative styles.

NAD+ supplement potentiates tumor-killing function by rescuing defective TUB-mediated NAMPT transcription in tumor-infiltrated T cells.

Although tumor-infiltrating lymphocytes (TILs) maintain their ability to proliferate, persist, and eradicate tumors, they are frequently dysfunctional in situ. By performing both whole-genome CRISPR and metabolic inhibitor screens, we identify that nicotinamide phosphoribosyltransferase (NAMPT) is required for T cell activation. NAMPT is low in TILs, and its expression is controlled by the transcriptional factor Tubby (TUB), whose activity depends on the T cell receptor-phospholipase C gamma (TCR-PLCγ) signaling axis. The intracellular level of NAD+, whose synthesis is dependent on the NAMPT-mediated salvage pathway, is also decreased in TILs. Liquid chromatography-mass spectrometry (LC-MS) and isotopic labeling studies confirm that NAD+ depletion led to suppressed glycolysis, disrupted mitochondrial function, and dampened ATP synthesis. Excitingly, both adoptive CAR-T and anti-PD1 immune checkpoint blockade mouse models demonstrate that NAD+ supplementation enhanced the tumor-killing efficacy of T cells. Collectively, this study reveals that an impaired TCR-TUB-NAMPT-NAD+ axis leads to T cell dysfunction in the tumor microenvironment, and an over-the-counter nutrient supplement of NAD+ could boost T-cell-based immunotherapy.

Two approaches reveal a new paradigm of 'switchable or genetics-influenced allele-specific DNA methylation' with potential in human disease.

Imprinted genes are vulnerable to environmental influences during early embryonic development, thereby contributing to the onset of disease in adulthood. Monoallelic methylation at several germline imprints has been reported as DNMT1-dependent. However, which of these two epigenetic attributes, DNMT1-dependence or allelic methylation, renders imprinted genes susceptible to environmental stressors has not been determined. Herein, we developed a new approach, referred to as NORED, to identify 2468 DNMT1-dependent DNA methylation patterns in the mouse genome. We further developed an algorithm based on a genetic variation-independent approach (referred to as MethylMosaic) to detect 2487 regions with bimodal methylation patterns. Two approaches identified 207 regions, including known imprinted germline allele-specific methylation patterns (ASMs), that were both NORED and MethylMosaic regions. Examination of methylation in four independent mouse embryonic stem cell lines shows that two regions identified by both NORED and MethylMosaic (Hcn2 and Park7) did not display parent-of-origin-dependent allelic methylation. In these four F1 hybrid cell lines, genetic variation in Cast allele at Hcn2 locus introduces a transcription factor binding site for MTF-1 that may predispose Cast allelic hypomethylation in a reciprocal cross with either C57 or 129 strains. In contrast, each allele of Hcn2 ASM in J1 inbred cell line and Park7 ASM in four F1 hybrid cell lines seems to exhibit similar propensity to be either hypo- or hypermethylated, suggesting a 'random, switchable' ASM. Together with published results, our data on ASMs prompted us to propose a hypothesis of regional 'autosomal chromosome inactivation (ACI)' that may control a subset of autosomal genes. Therefore, our results open a new avenue to understand monoallelic methylation and provide a rich resource of candidate genes to examine in environmental and nutritional exposure models.

Cellulase-assisted extraction, characterization, and bioactivity of polysaccharides from Polygonatum odoratum.

Cellulase-assisted extraction of polysaccharides from Polygonatum odoratum (CPP) was optimized by response surface methodology (RSM) and the extracted CPP's preliminary chemical characteristics, as well as antioxidant and immunomodulatory activities were also investigated. The optimal extraction parameters comprised an extraction temperature of 58.21 °C, an extraction time of 3.18 h, pH value of 5.8, and cellulase amount of 6.0%. Under these conditions, the relative yield was 15.76%, higher than the yield achieved with hot water extracted polysaccharide (HPP). Chemical composition analysis demonstrated that CPP and HPP consisted of mannose, glucosamine, rhamnose, glucose, galactose, and arabinose with a molecular ratio of 7.80:1.08:1.63:65.93:3.58:1.00 and 11.22:0.23:0.23:17.59:2.73:9.10, respectively. The molecular weight distribution of CPP was lower and more homogeneous compared with HPP. CPP exhibited stronger antioxidant activities than HPP, including DPPH radical scavenging activity and reducing power. Both CPP and HPP could significantly promote the proliferation and neutral red phagocytosis of RAW 264.7 macrophage cells in vitro. These results indicate that the cellulase-assisted extraction method influenced the physicochemical characteristics, and consequently, the functional activities of polysaccharides, suggesting the cellulose-assisted method may be a viable option for extraction polysaccharides from P. odoratum.

A preliminary study of side population cells in human gastric cancer cell line HGC-27.

BACKGROUND: Cancer stem cell-like side population (SP) cells, which may be responsible for recurrence, tumor metastasis, and resistance to cancer therapy, have been identified and characterized in several types of cell lines from gastric cancer. However, there is no report on isolation of SP cells from human gastric cancer cell line HGC-27. This study aims to analyze the proportion of SP cells in HGC-27 cell line, differentiate SP from non-side population (NSP) cells, and determine whether the SP cells have certain biological properties of stem cells. MATERIAL AND METHODS: (1) HGC-27 suspension was prepared and stained with Hoechst33342 and PI for flow cytometric isolation of SP (2). Differences in proliferation and stemness-related gene expression profiles (CD133, CD44, OCT-4, MDR1, EpCAM, and ABCG2) between SP and NSP cells were detected by gastric formation assay and quantitative real-time PCR (3). Oncogenicity of SP and NSP cells was determined in nude mice in vivo. RESULTS: (1) SP cells accounted for 0.1-1.0% of HGC-27 cells, and decreased to 0% after verapamil inhibition. Using flow cytometry, we sorted 7.5×105 SP cells and most HGC-27 cells were NSP cells (2). Gastric formation assay and MTT demonstrated that there was a significant difference in proliferation between SP and NSP cells. Gene expression analysis showed that the expression of genes was significantly higher in SP cells (3). The oncogenicity experiment in nude mice revealed that 105 SP cells were able to form tumors, which demonstrated higher tumorigenicity than non-SP cells. CONCLUSIONS: These results collectively suggested that SP cells from HGC-27 cell line have some cancer stem cell properties and could be used for studying the pathogenesis of gastric cancer, which may contribute to discovery of novel therapeutic targets.

A new hepoprotective saponin from Semen Celosia cristatae.

A new triterpenoid saponin, named semenoside A (1), was isolated from Semen Celosia cristatae. Its structure was elucidated on the basis of 1D, 2D NMR, HR-FAB-MS and ESI-MS techniques, and physicochemical properties. The hepatoprotective activity of semenoside A with an oral dose of 1.0, 2.0 and 4.0mg/kg, respectively, were investigated by carbon tetrachloride (CCl(4))-induced hepatotoxicity in mice. The results indicated that it had significant hepatoprotective effects (p < 0.01).

A new neuroprotective bakkenolide from the rhizome of Peatasites tatewakianus.

Constituents of the fruits of Peatasites tatewakianus were investigated. A new compound, namely bakkenolide-VI (1), was isolated. The structures was elucidated on the basis of 1D, 2D NMR, TOF-MS and ESI-MS techniques, and physicochemical properties. The neuroprotective activity of the new compound was assayed with primary cultured neurons exposed to oxygen-glucose deprivation and oxidative insults.