Bayasi Guleng

Previous studies have highlighted the role of genetic predispositions in disease, and several genes had been identified as important in Crohn’s disease (CD). However, many of these genes are likely rare and not associated with susceptibility in Chinese CD patients. We found 294 shared identical variants in the CD patients of which 26 were validated by Sanger sequencing. Two heterozygous IFN variants (IFNA10 c.60 T > A; IFNA4 c.60 A > T) were identified as significantly associated with CD susceptibility. The single-nucleotide changes alter a cysteine situated before the signal peptide cleavage site to a stop code (TGA) in IFNA10 result in the serum levels of IFNA10 were significantly decreased in the CD patients compared to the controls. Furthermore, the IFNA10 and IFNA4 mutants resulted in an impairment of the suppression of HCV RNA replication in HuH7 cells, and the administration of the recombinant IFN subtypes restored DSS-induced colonic inflammation through the upregulation of CD4⁺ Treg cells. We identified heterozygous IFNA10 and IFNA4 variants as a cause of impaired function and CD susceptibility genes in Chinese patients from multiple center based study. These findings might provide clues in the understanding of the genetic heterogeneity of CD and lead to better screening and improved treatment.

Colorectal cancer (CRC) is one of the most commonly diagnosed cancers and a major cause of cancer death. However, the molecular mechanisms underlying CRC initiation, growth and metastasis are poorly understood. Dragon (RGMb), a member of the repulsive guidance molecule (RGM) family, has been recently identified as a co-receptor for bone morphogenetic protein (BMP) signaling, but the role of Dragon in CRC development is undefined. Here, we show that Dragon expression was increased in colon cancer tissues compared to control tissues in CAC mouse model and in human patients. Dragon promoted proliferation of CT26.WT and CMT93 colon cancer cells and accelerated tumor growth in the xenograft mouse model. Dragon’s action on colon cancer development was mediated via the BMP4-Smad1/5/8 and Erk1/2 pathways. Therefore, our results have revealed that Dragon is a novel gene that promotes CRC growth through the BMP pathway. Dragon may be exploited as a potential therapeutic target for CRC treatment.

As a secreted protein, serum trefoil factor 3 (TFF3) has been reported to be a biomarker of several malignancies. We further investigated whether TFF3 can be applied as a biomarker for and predictor of responses to chemotherapy in gastrointestinal cancer.

Trefoil factor family 1 (TFF1) is a member of the TFF-domain peptide family involved in epithelial restitution and cell motility. Recently, we screened Piezo1 as a candidate TFF1-binding protein. We aimed to confirm Piezo1 as a novel TFF1 binding protein and to assess the role of this interaction in mediating gastric cancer cell mobility. This interaction was confirmed by co-immunoprecipitation and co-localisation of TFF1 and Piezo1 in GES-1 cells. We used stable RNA interference to knockdown Piezo1 protein expression and restored the expression of TFF1 in the gastric cancer cell lines SGC-7901 and BGC-823. Cell motility was evaluated using invasion assay and migration assay in vitro. The expression levels of the integrin subunits β1, β5, α1 as well as the expression of β-catenin and E-cadherin were detected by Western blot. We demonstrate that TFF1, but not TFF2 or TFF3, bind to and co-localize with Piezo1 in the cytoplasm in vitro. TFF1 interacts with the C-terminal portion of the Piezo1 protein. Wound healing and trans-well assays demonstrated that the restored expression of TFF1 promoted cell mobility in gastric cancer cells, and this effect was attenuated by the knockdown of Piezo1. Western blots demonstrated the decreased expression of integrin β1 in Piezo1-knockdown cells. Our data demonstrate that Piezo1 is a novel TFF1 binding protein that is important for TFF1-mediated cell migration and suggest that this interaction may be a therapeutic target in the invasion and metastasis of gastric cancer.

Inflammatory bowel disease (IBD) can lead to an increased risk of developing colorectal cancer (CRC). The aim of this study was to establish a model for combined bone marrow transplantation (BMT) and colitis-associated colorectal cancer (CAC) and to define the contribution of BM-derived cells during the inflammation associated with carcinogenesis. We established a model for BMT using green fluorescent protein (GFP) transgenic mice, followed by AOM/DSS-induced CAC, and performed confocal microscopy analysis on in vivo living tissue and frozen tumor sections. Our imaging analyses showed that GFP-positive cells extensively infiltrated the tumor stroma and that some WGA and GFP or CD31 and GFP double-positive cells were observed in the lining of tumor vessels. Flow cytometry analysis of the tumor-infiltrating cells showed that the GFP-positive CD11c+ DCs cells were one-third of the GFP+/CD11C- cells, and that half of these DCs (0.96% vs 1.02%) were GFP-positive BM-derived cells. The majority of CD4⁺ T cells were GFP-negative (12.02% vs 1.9%), and we discovered a novel CD4⁺ CD11c⁺ DC subset (0.34% vs 1.64%). In conclusion, we defined the distribution of BM-derived endothelial cells, CD11c⁺ DCs and CD4⁺ T cells in tumors. This model might be useful for elucidating the diverse BM-derived cell types and functions during the progression of colitis-associated colorectal cancer.

The role of Pokemon (POK erythroid myeloid ontogenic actor), a recently identified POK transcription factor with proto-oncogenic activity, in hepatocellular carcinogenesis has only been assessed by a few studies. Our previous study revealed that Pokemon is overexpressed in hepatocellular carcinomas (HCC) and promotes HCC cell proliferation and migration via an AKT- and ERK- dependent manner. In the present study, we used the TUNEL assay and FACS analysis to demonstrate that oxaliplatin induced apoptosis was significantly increased in cells with silenced Pokemon. Western blots showed that p53 expression and phosphorylation were significantly increased in Pokemon defective cells, thereby initiating the mitochondria-mediated and death receptor-mediated apoptotic pathways. In the mitochondria-mediated pathway, expression of pro-apoptotic Bcl-2 family members (including Bad, Bid, Bim and Puma) as well as AIF was increased and decreasing the mitochondrial membrane potential resulted in cytochrome C released from mitochondrial in HepG2 si-Pokemon cells. In addition, upon oxaliplatin treatment of Pokemon-silenced cells, the FAS receptor, FADD and their downstream targets caspase-10 and caspase-8 were activated, causing increased release of caspase-8 active fragments p18 and p10. Increased activated caspase-8-mediated cleavage and activation of downstream effector caspases such as caspase-9 and caspase-3 was observed in HepG2 si-Pokemon cells as compared to control. Therefore, Pokemon might serve as an important mediator of crosstalk between intrinsic and extrinsic apoptotic pathways in HCC cells. Moreover, our findings suggest that Pokemon could be an attractive therapeutic target gene for human cancer therapy.

EGFR activation and PKM2 expression are instrumental in tumorigenesis. EGFR activation regulates PKM2 functions in a subcellular compartment-dependent manner and promotes gene transcription and tumor growth. In addition, PKM2 is upregulated in EGFR-induced pathways in glioma malignancies. However, we found that PKM2 could also regulate the activity of the EGF/EGFR signaling pathway in gastric cancer cells. We aimed to define the biological mechanisms for PKM2 in regulating the cell motility and invasion. We employed stable transfection with short hairpin RNA to stably silence the expression of PKM2 in the BGC823, SGC7901 and AGS gastric cancer cell lines. The effects of PKM2 in vitro were determined by assessing cell migration and invasion. Immunohistochemical analysis was used to explore the relationship among PKM2 and other proteins. Our results indicate that the knockdown of PKM2 decreased the activity of E-cadherin and enhanced the EGF/EGFR signaling pathway in the gastric cell lines BGC823 and SGC7901 that were positive for E-cadherin expression. However, in the undifferentiated gastric carcinoma cell line AGS, which lacks E-cadherin expression, PKM2 promoted cell migration and invasion. Immunohistochemical analyses showed that the levels of E-cadherin expression, ERK1/2 phosphorylation, and cytoplasmic PKM2 expression were correlated with each other. PKM2 may play different roles in differently differentiated gastric cancer cell types, and this finding would be consistent with the previous clinical research. The results of our study reveal an important link between PKM2 and E-cadherin during EGFR-stimulated gastric cancer cell motility and invasion.