Dan-Feng Sun

Inhibition of mTOR signalling potentiates the effects of trichostatin A in human gastric cancer cell lines by promoting histone acetylation

Deregulation of the mammalian target of rapamycin pathway (mTOR pathway) is associated with human cancer. The relationship between mTOR pathway and histone acetylation is still unclear in gastric cancer (GC). Immunohistochemistry was used to examine the phosphorylation of mTOR and eukaryotic translation initiation factor 4E‐binding protein 1 (4E‐BP1) in GC tissues. MKN45 and SGC7901 cells were treated with the mTOR inhibitor rapamycin (RAPA) alone or in combination with the phosphatidylinositol 3‐kinase inhibitor LY294002 and the histone deacetylase (HDAC) inhibitor trichostatin A (TSA). Small interfering RNA (siRNA) technology was also used to knockdown mTOR. Phosphorylated mTOR and phosphorylated 4E‐BP1 were expressed in 71.1% and 68.4% of the human GC tissues tested, respectively; significantly higher than the levels in para‐cancerous tissues (50% and 57.9%) and normal tissues (44.6% and 29%). RAPA markedly inhibited cell proliferation, induced G1 cell cycle arrest, and reduced phosphorylation of p70 S6 protein kinase (p70S6K) and 4E‐BP1 in GC cells, particularly when used in combination with LY294002 or TSA. The mRNA expression of the tumour suppressor gene p21WAF1 increased significantly in GC cells treated with both RAPA and TSA. Histone acetylation also increased after RAPA and TSA treatment or siRNA knockdown of mTOR. Our findings suggest that the mTOR pathway is activated in GC, and also that inhibition of mTOR enhances the ability of TSA to suppress cell proliferation and lead to cell cycle arrest via increasing histone acetylation and p21WAF1 transcription in human MKN45 and SGC7901 GC cells.

Th22 cells control colon tumorigenesis through STAT3 and Polycomb Repression complex 2 signaling

ABSTRACT Th22 cells traffic to and retain in the colon cancer microenvironment, and target core stem cell genes and promote colon cancer stemness via STAT3 and H3K79me2 signaling pathway and contribute to colon carcinogenesis. However, whether Th22 cells affect colon cancer cell proliferation and apoptosis remains unknown. We studied the interaction between Th22 cells and colon cancer cells in the colon cancer microenvironment. Colon cancer proliferation was examined by flow cytometry analysis and H3 thymidine incorporation. Cell cycle related genes were quantified by real-time PCR and Western blotting. We transfected colon cancer cells with lentiviral vector encoding specific gene shRNAs and used chromatin immunoprecipitation (ChIP) assay to determine the genetic signaling involved in interleukin (IL)-22-mediated colon cancer cell proliferation. We showed that Th22 cells released IL-22 and stimulated colon cancer proliferation. Mechanistically, IL-22 activated STAT3, and subsequently STAT3 bound to the promoter areas of the Polycomb Repression complex 2 (PRC2) components SUZ12 and EED, and stimulated the expression of PRC2. Consequently, the activated PRC2 catalyzed the promoters of the cell cycle check-point genes p16 and p21, and inhibited their expression through H3K27me3-mediated histone methylation, and ultimately caused colon cancer cell proliferation. Bioinformatics analysis revealed that the levels of IL-22 expression positively correlated with the levels of genes controlling cancer proliferation and cell cycling in colon cancer. In addition to controlling colon cancer stemness, Th22 cells support colon carcinogenesis via affecting colon cancer cell proliferation through a distinct histone modification.

Knock‐down of methylenetetrahydrofolate reductase reduces gastric cancer cell survival: An in vitro study

The present study aimed to investigate the effect of knocking‐down methylenetetrahydrofolate reductase (MTHFR) on the survival of the human gastric cancer cell line MKN45. Antisense and small interfering RNA (siRNA) plasmids were used to target MTHFR in MKN45. Meanwhile, we also constructed a wild‐type MTHFR plasmid to assess the effect of over‐expression of this protein on cell viability. The knock‐down of MTHFR decreased cell survival by approximately 30% compared to the control and resulted in cell cycle arrest at the G2 phase. These cells also had lower levels of c‐myc compared to control cells, while over‐expression of MTHFR increased cell proliferation and induced the down‐regulation of p21WAF1 and hMLH1. Inhibiting MTHFR with either antisense or siRNA decreases the viability of methionine‐dependent transformed gastric cancer cells and suggests that MTHFR inhibition may be a novel anticancer approach.

Sirtuin5 contributes to colorectal carcinogenesis by enhancing glutaminolysis in a deglutarylation-dependent manner

Reversible post-translational modifications represent a mechanism to control tumor metabolism. Here we show that mitochondrial Sirtuin5 (SIRT5), which mediates lysine desuccinylation, deglutarylation, and demalonylation, plays a role in colorectal cancer (CRC) glutamine metabolic rewiring. Metabolic profiling identifies that deletion of SIRT5 causes a marked decrease in 13C-glutamine incorporation into tricarboxylic-acid (TCA) cycle intermediates and glutamine-derived non-essential amino acids. This reduces the building blocks required for rapid growth. Mechanistically, the direct interaction between SIRT5 and glutamate dehydrogenase 1 (GLUD1) causes deglutarylation and functional activation of GLUD1, a critical regulator of cellular glutaminolysis. Consistently, GLUD1 knockdown diminishes SIRT5-induced proliferation, both in vivo and in vitro. Clinically, overexpression of SIRT5 is significantly correlated with poor prognosis in CRC. Thus, SIRT5 supports the anaplerotic entry of glutamine into the TCA cycle in malignant phenotypes of CRC via activating GLUD1.Tumour metabolism can be controlled through post-translational modifications. Here the authors show that Sirtuin5 promotes glutaminolysis in colorectal cancer cells via glutamate dehydrogenase-1, a critical regulator of glutaminolysis, inducing its deglutarylation and functional activation.

Fecal Clostridium symbiosum for Noninvasive Detection of Early and Advanced Colorectal Cancer: Test and Validation Studies

Objective Current non-invasive early detection of colorectal cancer (CRC) requires improvement. We aimed to identified a fecal Clostridium symbiosum-based biomarker for early and advanced colorectal cancer detection. Design In the test stage, the relative abundance of Clostridium symbiosum (C. symbiosum) was measured by qPCR in 781 cases including 242 controls, 212 colorectal adenoma (CRA) patients, 109 early CRC (tumor restricted to the submucosa) patients, 218 advanced CRC patients. The prediction accuracy was compared to Fusobacterium nucleatum (F. nucleatum), fecal immunochemical test (FIT) and CEA (carcinoembryonic antigen) and validated in an independent cohort of 256 subjects. Current status of the trial:ongoing/still enrolling. Primary endpoint:June, 2017 (Clinicaltrials.gov Identifier NCT02845973). Results Significant stepwise increase of C. symbiosum abundance was found in CRA, early CRC and advanced CRC (P < 0.01). C. symbiosum outperformed all the other markers in early CRC prediction performance. The combination of C. symbiosum and FIT achieved better performance (0.803 for test cohort and 0.707 for validation cohort). For overall discrimination of CRCs, the combination of all above markers achieved the performance of 0.876. Conclusions Fecal C. symbiosum is a promising biomarker for early and noninvasive detection of colorectal cancer, being more effective than F. nucleatum, FIT and CEA. Combining C. symbiosum and FIT or CEA may improve the diagnosis power.

Corrigendum to “Fecal Clostridium Symbiosum for Noninvasive Detection of Early and Advanced Colorectal Cancer: Test and Validation Studies” [Ebiomedicine 25 (2017) 32–40](S2352396417303973)(10.1016/j.ebiom.2017.10.005)

Yuan-Hong Xie , Qin-Yan Gao , Guo-Xiang Cai , Xiao-Min Sun , Tian-Hui Zou , Hui-Min Chen , Si-Yi Yu , Yi-Wen Qiu , Wei-Qi Gu , Xiao-Yu Chen , Yun Cui , Danfeng Sun , Zhan-Ju Liu , San-Jun Cai ⁎, Jie Xu , Ying-Xuan Chen , Jing-Yuan Fang a,b a Division of Gastroenterology and Hepatology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200001, China b Institute of Digestive Disease, State Key Laboratory for Oncogenes and Related Genes, Key Laboratory of Gastroenterology &Hepatology,Ministry of Health, 145Middle Shandong Road, Shanghai 200001, China c Department of Colorectal Surgery, Fudan University Shanghai Cancer Center, Fudan University, Shanghai, China d Department of Gastroenterology, The Shanghai Tenth Peoples Hospital, Tongji University, Shanghai, China

Retracted: Role of STAT3 and vitamin D receptor in EZH2-mediated invasion of human colorectal cancer

The above article from The Journal of Pathology, published online on 7 June 2013 in Wiley Online Library (wileyonlinelibrary.com), has been retracted by agreement between the authors, the journal Editor‐in‐Chief, Prof. C. Simon Herrington, and John Wiley & Sons Limited. Some sequences in Figure 6C were mistakenly identified, with consequent errors in the description of this figure and in the Materials and Methods section. Additionally, in Figures 5C, 5F and 7 some images were duplicated and erroneously presented as unique. The authors apologise to readers of the journal.

Retracted : Role of STAT3 and vitamin D receptor in EZH2 -mediated invasion of human colorectal cancer : STAT3 up-regulates EZH2 which may deregulate VDR

The above article from The Journal of Pathology, published online on 7 June 2013 in Wiley Online Library (wileyonlinelibrary.com), has been retracted by agreement between the authors, the journal Editor‐in‐Chief, Prof. C. Simon Herrington, and John Wiley & Sons Limited. Some sequences in Figure 6C were mistakenly identified, with consequent errors in the description of this figure and in the Materials and Methods section. Additionally, in Figures 5C, 5F and 7 some images were duplicated and erroneously presented as unique. The authors apologise to readers of the journal.