Long-term outcomes of endoscopic therapy versus surgical resection for 2-5 cm gastric gastrointestinal stromal tumors: A population-based comparative study.

BACKGROUND: Endoscopic therapy (ET) of gastrointestinal stromal tumors (GIST) has become a viable treatment. We intended to compare long-term outcomes of ET versus surgical resection for 2-5 cm GIST using the Surveillance, Epidemiology, and End Results (SEER) database. METHODS: A multicenter retrospective study was conducted to compare the long-term outcomes of patients treated with ET and surgical resection for GIST. The multivariate Cox proportional hazards models were used to identify predictors for patients survival. To balance the clinicopathologic characteristics, a 1:1 propensity score matching (PSM) was utilized. RESULTS: A total of 749 patients with 2-5 cm GIST were enrolled, of whom 113 accepted ET and 636 underwent surgical resection. Before PSM, there was no significant difference in long-term outcomes between ET and surgical resection (5-year overall survival (OS): 93.5% vs. 91.6%, P=0.374; 5-year cancer-specific survival (CSS): 99.1% vs. 96.5%, P=0.546; 10-year OS: 71.1% vs. 78.2%, P=0.374; 10-year CSS: 93.6% vs. 92.7%, P=0.546). After adjusting for the relevant variables using the multivariable Cox proportional hazards models, we observed that the ET and surgical resection groups were similar in OS (HR 0.726, 95%CI 0.457-1.153, P=0.175) and CSS (HR 1.286, 95%CI 0.474-3.488, P=0.621). After PSM, the long-term OS and CSS of patients with 2-5 cm GIST after ET and surgical resection were comparable. CONCLUSIONS: We found that the long-term survival of patients with 2-5 cm gastric GIST after ET and surgical resection were comparable. Further high-quality studies are needed to confirm the role of ET in 2-5 cm GIST.

GPR120 promotes neutrophil control of intestinal bacterial infection.

G-protein coupled receptor 120 (GPR 120) has been implicated in anti-inflammatory functions. However, how GPR120 regulates the neutrophil function remains unknown. This study investigated the role of GPR120 in the regulation of neutrophil function against enteric bacteria. 16S rRNA sequencing was used for measuring the gut microbiota of wild-type (WT) mice and Gpr120-/- mice. Citrobacter rodentium infection and dextran sulfate sodium (DSS)-induced colitis models were performed in WT and Gpr120-/- mice. Mouse peritoneal-derived primary neutrophils were used to determine the neutrophil functions. Gpr120-/- mice showed altered microbiota composition. Gpr120-/- mice exhibited less capacity to clear intestinal Citrobacter rodentium and more severe intestinal inflammation upon infection or DSS insults. Depletion of neutrophils decreased the intestinal clearance of Citrobacter rodentium. GPR120 agonist, CpdA, enhanced WT neutrophil production of reactive oxygen species (ROS) and extracellular traps (NETs), and GPR120-deficient neutrophils demonstrated a lower level of ROS and NETs. CpdA-treated neutrophils showed an enhanced capacity to inhibit the growth of Citrobacter rodentium, which was abrogated by the inhibition of either NETs or ROS. CpdA promoted neutrophil inhibition of the growth of commensal bacteria Escherichia coli O9:H4 and pathobiont Escherichia coli O83:H1 isolated from a Crohn's disease patient. Mechanically, mTOR activation and glycolysis mediated GPR120 induction of ROS and NETs in neutrophils. Additionally, CpdA promoted the neutrophil production of IL-17 and IL-22, and treatment with a conditioned medium of GPR120-activated neutrophils increased intestinal epithelial cell barrier functions. Our study demonstrated the critical role of GPR120 in neutrophils in protection against enteric bacterial invasion.

PBLD inhibits angiogenesis via impeding VEGF/VEGFR2-mediated microenvironmental cross-talk between HCC cells and endothelial cells.

Sustained anti-angiogenesis therapy increases the level of tumor hypoxia, leading to increased expression of HIF-1a, thereby contributing to the resistance to anti-angiogenesis therapy in hepatocellular carcinoma (HCC). Here, we report that phenazine biosynthesis-like domain-containing protein (PBLD) inhibits hypoxia-induced angiogenesis via ERK/HIF-1a/VEGF axis in HCC cells. Bioinformatic analysis of the TCGA database and clinical samples validation also identify a negative correlation between PBLD and angiogenesis-related genes expression including HIF-1a. Apart from the downregulation of HIF-1a/VEGF expression in HCC cells, PBLD also blocks VEGF receptor 2 (VEGFR2) on endothelial cells via HCC-derived exosomal miR-940. PBLD also activates TCF4 transcriptional promotion effects on miR-940 by directly interacting with it. Together, PBLD exerts an inhibitory effect on angiogenesis not only via blocking the VEGFR2 expression in endothelial cells, but also through downregulating HIF-1a-induced VEGF expression and secretion in HCC cells. These explorations may provide a theoretical basis for exploring new targets and strategies to overcome resistance to anti-angiogenesis therapy.

Tumor-suppressive function of EZH2 is through inhibiting glutaminase.

Tumors can use metabolic reprogramming to survive nutrient stress. Epigenetic regulators play a critical role in metabolic adaptation. Here we screened a sgRNA library to identify epigenetic regulators responsible for the vulnerability of colorectal cancer (CRC) cells to glucose deprivation and found that more EZH2-knockout cells survived glucose deprivation. Then, we showed that EZH2 expression was significantly downregulated in response to glucose deprivation in a glucose-sensitive CRC cell line, and EZH2-knockdown cells were more resistant to glucose deprivation. Mechanistically, EZH2 deficiency upregulated the expression of glutaminase (GLS) and promoted the production of glutamate, which in turn led to increased synthesis of intracellular glutathione (GSH) and eventually attenuated the reactive oxygen species (ROS)-mediated cell death induced by glucose deprivation. Although EZH2 functioned as an oncogene in cancer progression and EZH2 knockout abolished colorectal cancer development in a mouse model, here we revealed a mechanistic link between EZH2 and metabolic reprogramming via the direct regulation of GLS expression and observed a negative correlation between EZH2 and GLS expression in colorectal cancer tissues. These findings further confirmed the importance of heterogeneity, provided an explanation for the clinical tolerance of cancer cells to EZH2 inhibitors from the perspective of metabolism, and proposed the possibility of combining EZH2 inhibitors and glutamine metabolism inhibitors for the treatment of cancer.

MiR-452-5p promotes colorectal cancer progression by regulating an ERK/MAPK positive feedback loop.

BACKGROUND: MiR-452-5p plays an essential role in the development of a variety of tumors, but little is known about its biological function and mechanism in colorectal cancer (CRC). METHODS: The expression levels of miR-452-5p in CRC tissues and cells were detected by real-time quantitative PCR (qRT-PCR). Besides, the biological effects of miR-452-5p on CRC were investigated by functional experiments in vitro and in vivo. Furthermore, bioinformatics analysis, dual-luciferase reporter assay, chromatin immunecipitation assay, western blotting and recovery experiments were implemented to investigate the underlying molecular mechanism. RESULTS: The expression level of miR-452-5p was up-regulated in CRC tissues. MiR-452-5p promoted CRC cell proliferation, cell cycle transition and chemoresistance, and inhibited cell apoptosis. Moreover, miR-452-5p directly targeted PKN2 and DUSP6 and subsequently activated the ERK/MAPK signaling pathway, and it was transcriptionally regulated by c-Jun. CONCLUSION: To conclude, miR-452-5p expression is up-regulated in CRC, which promotes the progression of CRC by activating the miR-452-5p-PKN2/DUSP6-c-Jun positive feedback loop. These findings indicate that miR-452-5p may act as a potential therapeutic target and clinical response biomarker for CRC.

Lactate and TGF-ß antagonistically regulate inflammasome activation in the tumor microenvironment.

The tumor microenvironment significantly affects tumor progression, and tumor cells can also remodel the tumor microenvironment through complex interaction. Inflammasomes are innate immune system receptors/sensors that regulate an inflammatory response mainly mediated by the nucleotide-binding oligomerization domain-like receptors in macrophages, which can also influence the formation, progression and therapeutic response of cancer. However, the effects of tumor-derived factors in the microenvironment on inflammasomes have rarely been reported. In this study, we found that lactate, as the main metabolite of tumor cells could specifically activate the nucleotide-binding oligomerization domain, leucine rich repeat and pyrin domain-containing protein 3 inflammasome through increasing the level of reactive oxygen species (ROS) in THP-1-derived macrophages. Furthermore, we showed that transforming growth factor-ß (TGF-ß), a cytokine accumulated in the tumor microenvironment, could be induced by lactate treatment in tumor cells, and in turn inhibit inflammasome activation induced by lactate and other canonical ligands in macrophages. In addition, TGF-ß might induce autophagy of macrophages in a SMAD-dependent manner, leading to ROS clearance and eventually inhibiting the activation of inflammasomes. Collectively, these results indicated that in the tumor microenvironment, tumor-derived lactate could act as a danger signal alerting innate immunity, but nevertheless tumor cells produced more TGF-ß to avoid immune surveillance.

CPEB3 functions as a tumor suppressor in colorectal cancer via JAK/STAT signaling.

As RNA-binding proteins, cytoplasmic polyadenylation element binding proteins (CPEBs) have drawn increasing attention for their function of controlling gene expression related to malignant transformation via post-transcriptional regulation. However, the contribution of CPEB3 to malignant development in cancers is poorly understood. In this study, we explored the clinical, biological, and mechanical role of CPEB3 in colorectal cancer progression. We showed that colorectal cancer tissues exhibited dampened CPEB3 expression which was closely associated with poor prognosis in patients with colorectal cancer (47 vs. 62 months, P = 0.035, n=99). Down-regulation CPEB3 promoted proliferation, migration, and invasion in colorectal cancer cells and vice versa. Mechanistically, CPEB3 performed as an RNA binding protein binding to 3'UTR of JAK1 mRNA to inhibit JAK/STAT pathways in colorectal cancer cells. Knockdown of CPEB3 induced active JAK-STAT signaling, thereby triggering the proliferation and metastasis capacity of colorectal cancer cells. These results suggest that CPEB3 functions as a tumor suppressor in colorectal cancer through its post-transcriptional regulation of JAK/STAT signaling. Implications: This study identified a novel role of the RNA binding protein CPEB3 in inhibiting cell proliferation and migration as well as the underlining mechanisms in colorectal cancer cells.

Cancer-associated fibroblasts-derived exosomal miR-17-5p promotes colorectal cancer aggressive phenotype by initiating a RUNX3/MYC/TGF-ß1 positive feedback loop.

Cancer-associated fibroblasts (CAFs) are the main stromal cells in the tumour microenvironment (TME). We found that the distribution of CAFs was significantly increased with tumour progression and led to a poor prognosis. In vitro and in vivo assays revealed that CAFs enhanced colorectal cancer (CRC) metastasis. Based on extraction and identification of exosomes of CAFs and normal fibroblasts (NFs), CAFs-exo showed higher expression of miR-17-5p than NFs-exo and could deliver exosomal miR-17-5p from parental CAFs to CRC cells. Further exploration verified that miR-17-5p influenced CRC metastasis capacity and directly targeted 3'-untranslated regions (UTRs) of RUNX family transcription factor 3(RUNX3). Our findings further revealed that RUNX3 interacted with MYC proto-oncogene(MYC) and that both RUNX3 and MYC bound to the promoter of transforming growth factor beta1(TGF-ß1) at base pairs 1005-1296, thereby activating the TGF-ß signalling pathway and contributing to tumour progression. In addition, RUNX3/MYC/TGF-ß1 signalling sustained autocrine TGF-ß1 to activate CAFs, and activated CAFs released more exosomal miR-17-5p to CRC cells, forming a positive feedback loop for CRC progression. Taken together, these data provide a new understanding of the potential diagnostic value of exosomal miR-17-5p in CRC.

CD73 promotes tumor metastasis by modulating RICS/RhoA signaling and EMT in gastric cancer.

Tumor microenvironment plays vital roles in shaping cancer diversity, and CD73 (ecto-5'-nucleotidase; NT5E) is an emerging immune checkpoint in modulating cancer progression via conversion of immunostimulatory ATP into immunosuppressive adenosine. However, how the CD73 is regulated and how it functions in the progression of cancer are largely unknown. Here, we showed that CD73 was overexpressed and correlated with poor prognosis of gastric cancer. CD73 links adenosinergic signaling in microenvironment switching to induction of epithelial-to-mesenchymal transition phenotype in gastric cancer during metastasis. Further pathway and gene set enrichment analysis of transcriptome data revealed the modulation role of CD73 in RICS/RhoA signaling by its extracellular function in adenosinergic pathway, which subsequently inhibited phosphorylation of LIMK/cofilin and promoted ß-catenin activation. Pharmacological inhibition of CD73 adenosinergic signaling was found to induce RICS dysfunction. Dissemination and hematogenous metastasis model showed that targeting CD73 in gastric cancer could suppress experimental metastasis. To conclude, it substantiates CD73 as a target for treatment of gastric cancer metastasis and verifies RICS as an intracellular functional molecule linking CD73/adenosinergic signaling switching to RhoA/LIMK/cofilin pathway.

MiR-532-3p suppresses colorectal cancer progression by disrupting the ETS1/TGM2 axis-mediated Wnt/ß-catenin signaling.

The expression panel of plasma microRNA defined miR-532-3p as a valuable biomarker for colorectal adenoma (CRA). However, its expression pattern and function in colorectal cancer (CRC) have remained unclear. The present study investigated the expression levels of miR-532-3p and found that it was in situ downregulated both in CRA and CRC. Moreover, it functioned as a sensitizer for chemotherapy in CRC by inducing cell cycle arrest and early apoptosis via its activating effects on p53 and apoptotic signaling pathways. In addition, miR-532-3p was found to restrain cell growth, metastasis, and epithelial-mesenchymal transition (EMT) phenotype of CRC. A study on the mechanism behind these effects revealed that miR-532-3p directly binds to 3'UTR regions of ETS1 and TGM2, ultimately repressing the canonical Wnt/ß-catenin signaling. Further investigation showed that TGM2 was transcriptionally regulated by ETS1 and ETS1/TGM2 axis served as a vital functional target of miR-532-3p in suppressing CRC progression. To conclude, miR-532-3p mimics could act as potential candidate for molecular therapy in CRC through inactivation of the canonical Wnt/ß-catenin signaling and enhancement of chemosensitivity.

LncRNA SNHG6 promotes chemoresistance through ULK1-induced autophagy by sponging miR-26a-5p in colorectal cancer cells.

BACKGROUND: Chemotherapy resistance is one of the main causes of recurrence in colorectal cancer (CRC) patients and leads to poor prognosis. Long noncoding RNAs (lncRNAs) have been reported to regulate chemoresistance. We aimed to determine the role of the lncRNA small nucleolar RNA host gene 6 (SNHG6) in CRC cell chemoresistance. METHODS: Cell drug sensitivity tests and flow cytometry were performed to analyze CRC cell chemoresistance. Animal models were used to determine chemoresistance in vivo, and micro RNA (miRNA) binding sites were detected by dual-luciferase reporter assays. Bioinformatics analysis was performed to predict miRNAs binding to SNHG6 and target genes of miR-26a-5p. SNHG6/miR-26a-5p/ULK1 axis and autophagy-related proteins were detected by qRT-PCR and western blotting. Furthermore, immunofluorescence was employed to confirm the presence of autophagosomes. RESULTS: SNHG6 enhanced CRC cell resistance to 5-fluorouracil (5-FU), promoted autophagy, inhibited 5-FU-induced apoptosis, and increased 5-FU resistance in vivo. Bioinformatics analysis showed that miR-26a-5p might bind to SNHG6 and target ULK1, and dual-luciferase reporter assays confirmed this activity. qRT-PCR and western blotting showed that SNHG6 was able to negatively regulate miR-26a-5p but correlated positively with ULK1. CONCLUSION: SNHG6 may promote chemoresistance through ULK1-induced autophagy by sponging miR-26a-5p in CRC cells.

RUNX1 promotes tumour metastasis by activating the Wnt/ß-catenin signalling pathway and EMT in colorectal cancer.

BACKGROUND: Runt-related transcription factor 1 (RUNX1) plays the roles of an oncogene and an anti-oncogene in epithelial tumours, and abnormally elevated RUNX1 has been suggested to contribute to the carcinogenesis of colorectal cancer (CRC). However, the mechanism remains unclear. METHODS: The expression of RUNX1 in CRC and normal tissues was detected by real-time quantitative PCR and Western blotting. The effect of RUNX1 on CRC migration and invasion was conducted by functional experiments in vitro and in vivo. Chromatin Immunoprecipitation assay verified the direct regulation of RUNX1 on the promoter of the KIT, which leads to the activation of Wnt/ß-catenin signaling. RESULTS: RUNX1 expression is upregulated in CRC tissues. Upregulated RUNX1 promotes cell metastasis and epithelial to mesenchymal transition (EMT) of CRC both in vitro and in vivo. Furthermore, RUNX1 can activate Wnt/ß-catenin signalling in CRC cells by directly interacting with ß-catenin and targeting the promoter and enhancer regions of KIT to promote KIT transcription. These observations demonstrate that RUNX1 upregulation is a common event in CRC specimens and is closely correlated with cancer metastasis and that RUNX1 promotes EMT of CRC cells by activating Wnt/ß-catenin signalling. Moreover, RUNX1 is regulated by Wnt/ß-catenin. CONCLUSION: Our findings first demonstrate that RUNX1 promotes CRC metastasis by activating the Wnt/ß-catenin signalling pathway and EMT.

LncRNA SNHG6 promotes proliferation, invasion and migration in colorectal cancer cells by activating TGF-ß/Smad signaling pathway via targeting UPF1 and inducing EMT via regulation of ZEB1.

Background: Long noncoding RNAs (lncRNAs) are non-protein coding transcripts longer than 200 nucleotides in length. They drive many important cancer phenotypes through their interactions with other cellular macromolecules including DNA, RNA and protein. Recent studies have identified numerous lncRNAs active in colorectal cancer (CRC). The lncRNA small nucleolar RNA host gene 6 (SNHG6) has been reported to have an oncogenic role in multiple cancers. However, the biological role and mechanism of SNHG6 in the tumorigenesis of CRC has not been reported in-deep. Methods: The Cancer Genome Atlas (TCGA) database and GEO database were used to identify SNHG6 expression in different human cancers and explore the relationship between SNHG6 expression and patient prognosis using Kaplan-Meier method analysis. SNHG6 expression in 77 pairs of clinical CRC tissues and different CRC cell lines were analyzed by quantitative real-time PCR (qRT-PCR). A CCK-8 assay was used to assess cell proliferation, transwell assay to detect the cell metastasis, and tumor growth was investigated with a nude mice model in vivo. Whether UPF1 and ZEB1 are downstream targets of SNHG6 was verified by bioinformatics target gene prediction, qRT-PCR and western blot. Results: TCGA data showed that SNHG6 was significantly upregulated in colorectal cancer samples in comparison with healthy data samples (P < 0.01). CRC patients with high levels of SNHG6 had a significantly shorter overall survival than those with low levels of SNHG6 (P = 0.0162). qRT-PCR confirmed that the expression of SNHG6 was significantly upregulated in CRC tissues and cell lines. Upregulation of SNHG6 expression induced RKO and HCT116 cell proliferation as well as RKO cell metastasis, while downregulation of SNHG6 expression supressed the proliferation and metastasis of RKO cells and tumor growth in vivo. UPF1 was upregulated and ZEB1 was decreased when SNHG6 knockdown, regulating the TGF-ß/Smad pathway and inducing EMT respectively. Conclusions: SNHG6 may play an oncogenic role in CRC cells by activating TGF-ß/Smad signaling pathway via targeting of UPF1 and inducing EMT via regulating ZEB1. This could be a prognostic biomarker and therapeutic target for CRC.

Imbalanced LIMK1 and LIMK2 expression leads to human colorectal cancer progression and metastasis via promoting ß-catenin nuclear translocation.

Epithelial-mesenchymal transition (EMT)-induced metastasis contributes to human colorectal cancer (CRC) progression, especially in advanced CRC. However, the underlying mechanism of ß-catenin in this process is elusive. We identified that LIM domain kinase (LIMK)2 was progressively downregulated with tumor progression from precancerous lesions to advanced cancer. Gain- and loss-of-function assays revealed that LIMK2 inhibits cell proliferation via cell cycle arrest at the G1-S transition and suppresses the ability of cell metastasis by restricting the EMT process. Reduced LIMK2 expression enhanced the nuclear accumulation of ß-catenin and activated the Wnt signaling pathway, thus contributing to tumor progression. A homolog of the LIMK family, LIMK1, which was overexpressed throughout tumor progression, served as a competitive inhibitor of LIMK2 via ß-catenin nuclear translocation. The imbalanced expression of LIMK1 and LIMK2 is important in CRC progression, and the combined effects provide a new insight into the mechanism of CRC progression. These findings provide a new understanding for LIMK-based anticancer therapy.

Downregulation of SAFB Sustains the NF-κB Pathway by Targeting TAK1 during the Progression of Colorectal Cancer.

Purpose: To investigate the role and the underlying mechanism of scaffold attachment factor B (SAFB) in the progression of colorectal cancer (CRC).Experimental Design: SAFB expression was analyzed in the Cancer Outlier Profile Analysis of Oncomine and in 175 paraffin-embedded archived CRC tissues. Gene Ontology analyses were performed to explore the mechanism of SAFB in CRC progression. Western blot, RT-PCR, luciferase assay, and chromatin immunoprecipitation (ChIP) were used to detect the regulation of transforming growth factor-ß-activated kinase 1 (TAK1) and NF-κB signaling by SAFB The role of SAFB in invasion, metastasis, and angiogenesis was investigated using in vitro and in vivo assays. The relationship between SAFB and TAK1 was analyzed in CRC tissues.Results: SAFB was downregulated in CRC tissues, and low expression of SAFB was significantly associated with an aggressive phenotype and poorer survival of CRC patients. The downregulation of SAFB activated NF-κB signaling by targeting the TAK1 promoter. Ectopic expression of SAFB inhibited the development of aggressive features and metastasis of CRC cells both in vitro and in vivo The overexpression of TAK1 could rescue the aggressive features in SAFB-overexpressed cells. Furthermore, the expression of SAFB in CRC tissues was negatively correlated with the expression of TAK1- and NF-κB-related genes.Conclusions: Our results show that SAFB regulated the activity of NF-κB signaling in CRC by targeting TAK1 This novel mechanism provides a comprehensive understanding of both SAFB and the NF-κB signaling pathway in the progression of CRC and indicates that the SAFB-TAK1-NF-κB axis is a potential target for early therapeutic intervention in CRC progression. Clin Cancer Res; 23(22); 7108-18. ©2017 AACR.

miR-450b-5p induced by oncogenic KRAS is required for colorectal cancer progression.

The development and progression of CRC are regarded as a complicated network and progressive event including genetic and/or epigenetic alterations. Recent researches revealed that MicroRNAs are biomarkers and regulators of CRC progression. Analyses of published microarray datasets revealed that miR-450b-5p was highly up-regulated in CRC tissues. In addition, high expression of miR-450b-5p was significantly associated with KRAS mutation. However, the role of miR-450b-5p in the progression of CRC remains unknown. Here, we sought to validate the expression of miR-450b-5p in CRC tissues and investigate the role and underlying mechanism of miR-450b-5p in the progression of CRC. The results revealed that miR-450b-5p was up-regulated in CRC tissues, high expression level of miR-450b-5p was positively associated with poor differentiation, advanced TNM classification and poor prognosis. Moreover, miR-450b-5p was especially high in KRAS-mutated cell lines and could be up-regulated by KRAS/AP-1 signaling. Functional validation revealed that overexpression of miR-450b-5p promoted cell proliferation and tumor growth while inhibited apoptosis of CRC cells. Furthermore, we demonstrated that miR-450b-5p directly bound the 3'-UTRs of SFRP2 and SIAH1, and activated Wnt/ß-Catenin signaling. In conclusion, miR-450b-5p induced by oncogenic KRAS is required for colorectal cancer progression. Collectively, our work helped to understand the precise role of miR-450b-5p in the progression of CRC, and might promote the development of new therapeutic strategies against CRC.