Knockdown of Circ_0003506 Impedes Radioresistance, Cell Growth, Migration and Invasion in Gastric Cancer.

BACKGROUND: Radioresistance is a major obstacle for clinical treatment of gastric cancer (GC). has_circ_0003506 (circ_0003506) was reported as an oncogenic factor in GC, but its effect on radioresistant GC is unclear. AIMS: This study aimed to explore the role of circ_0003506 in radioresistance and regulatory mechanism. METHODS: The expression detection was performed by real-time polymerase chain reaction. Cell survival was analyzed by colony formation assay. Cell proliferation was measured by Cell Counting Kit-8 assay and colony formation assay. Cell migration and invasion were examined using transwell assay. Cell apoptosis was assessed by flow cytometry. The target binding was confirmed via dual-luciferase reporter assay. The protein level was determined through western blot. Animal assay was performed for the functional exploration of circ_0003506 on radiosensitivity in vivo. RESULTS: Circ_0003506 was upregulated in radioresistant GC cells. Downregulation of circ_0003506 inhibited radioresistance to repress proliferation, migration and invasion but increase apoptosis in radioresistant GC cells. Circ_0003506 was a sponge of miR-1256. The effects of si-circ_0003506 on radioresistant GC cells were reverted by miR-1256 inhibitor. MiR-1256 suppressed tumor progression in radioresistant GC cells by downregulating bone morphogenetic protein type 2 receptor. Circ_0003506 regulated the level of bone morphogenetic protein type 2 receptor by targeting miR-1256. Downregulating circ_0003506 increased radiosensitivity of GC in vivo via regulating miR-1256 and bone morphogenetic protein type 2 receptor. CONCLUSION: Knockdown of circ_0003506 suppressed radioresistance in GC through the regulation of miR-1256/bone morphogenetic protein type 2 receptor axis. Circ_0003506 might be a therapeutic target in radiotherapy of GC.

Molecular mechanism of acute radiation enteritis revealed using proteomics and biological signaling network analysis in rats.

BACKGROUND AND AIMS: Radiation enteritis (RE) has emerged as a significant complication that can progress to severe gastrointestinal disease and the mechanisms underlying its genesis remain poorly understood. The aim of this study was to identify temporal changes in protein expression potentially associated with acute inflammation and to elucidate the mechanism underlying radiation enteritis genesis. METHODS: Male Sprague-Dawley rats were irradiated in the abdomen with a single dose of 10 Gy to establish an in vivo model of acute radiation enteritis. Two-dimensional fluorescence difference gel electrophoresis, matrix-assisted laser desorption/ionization time-of-flight spectrometer (MALDI-TOF) tandem mass spectrometry, and peptide mass fingerprinting were used to determine differentially expressed proteins between normal and inflamed intestinal mucosa. Additionally, differentially expressed proteins were evaluated by KO Based Annotation System to find the biological functions associated with acute radiation enteritis. RESULTS: Intensity changes of 86 spots were detected with statistical significance (ratio ≥ 1.5 or ≤ 1.5, P < 0.05). Sixty one of the 86 spots were identified by MALDI-TOF/TOF tandem mass spectrometry. These radiation-induced proteins with biological functions showed that the FAS pathway and glycolysis signaling pathways were significantly altered using the KOBAS tool. CONCLUSIONS: Our results reveal an underlying mechanism of radiation-induced acute enteritis, which may help clarify the pathogenesis of RE and point to potential targets for therapeutic interventions.

Screening for differentially methylated genes among human colorectal cancer tissues and normal mucosa by microarray chip.

UNLABELLED: High density DNA methylation microarrays were used to study the differences of gene methylation level in six pairs of colorectal cancer (CRC) and adjacent normal mucosa. We analyzed the profile of methylated genes by NimbleGen Microarray and the biologic functions by NIH-NAVID. In addition, preliminary validation studies were done in six pairs of samples by MSP (methylation-specific PCR). A total of 4,644 genes had a difference in methylation levels. Among them 2,296 were hypermethylated (log2ratio > 1), 2,348 genes were hypomethylated (log2ratio < -1), in which 293 hypermethylated and 313 hypomethylated genes were unmapped according to the NIH-NAVID. All these genes were randomly distributed on all the chromosomes. However, chromosome 1 contained the most of the hypermethylated genes (232 genes), followed by chromosome 19 (149 genes), chromosome 11 (144 genes), chromosome 2 (141 genes), chromosomes 3 (127 genes). Through the analysis of the statistics, There were 2 hypermethylated/3 hypomethylated genes involved in six pairs of samples simultaneously, followed by 10/14 in five samples, 34/37 in four samples, 101/113 in three samples, 341/377 in two samples, 1,808/1,804 in one sample. According to gene ontology analysis, some physiological processes play important roles in the cell division and the development of tumor, such as apoptosis, DNA repair, immune, cell cycle, cell cycle checkpoint, cell adhesion and invasion etc. Through Preliminary validation, there were two genes (St3gal6, Opcml) in thirty top-ranking genes shown hypermethylated in six pairs of CRC and adjacent normal mucosa. CONCLUSIONS: High density DNA methylation microarrays is an effective method for screening aberrantly methylated genes in CRC. The methylated genes should be further studied for diagnostic or prognostic markers for CRC.

Clinical outcomes after surgical resection of colorectal cancer in 1,294 patients.

BACKGROUND/AIMS: This study aimed to determine the overall survival time and clinical characteristics affecting the outcomes in patients with resectable colorectal cancer (CRC). METHODOLOGY: Clinical data from CRC patients who underwent surgical resections from 1994 to 2004 was analyzed retrospectively using the documented records and gastrointestinal tumor databases at the gastrointestinal institute. Univariate and multivariate analyses were conducted to investigate the association between clinical variables and overall survival time. RESULTS: A consecutive series of 1.294 CRC patients were enrolled for the final analyses. The five-year survival rates were 94.1%, 80.2%, 61.7% and 23.2% of patients with stage from I to IV CRC, respectively. One hundred and seven patients (8.3%) had disease recurrence during the follow-up with a median of 50.3 months. After radical surgical resections, patients with recurrence could still expect a five-year survival rate of 44.3%. Multivariate analysis showed that patient age >60 years, infiltrative tumor type, intestinal obstruction, poor tumor differentiation, disease recurrence and late TNM stage were associated with poor survival (all p<0.05). CONCLUSIONS: The overall postoperative survival in this series of patients with CRC was mainly affected by patient age, tumor morphology, bowel obstruction, histological grade, TNM stage and disease recurrence. For those patients with recurrence, surgical resection should be recommended primarily if the tumor is resectable.

Functional variants of -1318T > G and -673C > T in c-Jun promoter region associated with increased colorectal cancer risk by elevating promoter activity.

C-Jun plays important roles in the development of multiple cancers, but no well-designed association studies have been conducted to assess the roles of its genetic polymorphisms in cancer risk. In a cohort of 1016 pairs of colorectal cancer (CRC) patients and matched cancer-free controls, we investigated two genetic polymorphisms in the promoter regions of the c-Jun (rs4646999, -673C > T and rs2760501, -1318T > G) via the Taqman assay and evaluated the association between two polymorphisms and risk of CRC. We found that both the -1318G and -673C variant genotypes were associated with an increased risk of CRC [-1318TG: odds ratio (OR) = 1.26, 95% confidence interval (CI) = 1.04-1.54; -1318GG: OR = 1.63, 95% CI = 1.03-2.60; -673CT: OR = 1.60, 95% CI = 1.23-2.07; -673CC: OR = 1.80, 95% CI = 1.36-2.37]. Haplotype association analysis showed that compared with the carriers of -1318T-673T haplotype, carriers of the -1318T-673C, -1318G-673T, and -1318G-673C haplotypes all had a significantly increased risk of CRC (P < 0.05 for all). The combined genotypes incorporating both polymorphisms obtained a more significantly additive risk of CRC (one variant genotype: OR = 1.81, 95% CI = 1.30-2.51; two variant genotype: OR = 2.42, 95% CI = 1.70-3.44). Moreover, we found that the change of the -1318T to G allele interact with the -673T to C allele elevated the transcription activity of the c-Jun, and we confirmed the same trends by analyzing c-Jun protein expression in the CRC tissues from patients carrying different number of variant genotypes. This study suggests that -673C > T and -1318T > G genetic variants in c-Jun promoter regions contribute to an increased risk of CRC, possibly by elevating the transcription activity and protein expression levels that appeared to upregulate activity of c-Jun thus tumorigenesis.

Perivascular epithelioid cell tumor of gastrointestinal tract: case report and review of the literature.

Perivascular epithelioid cell tumors of gastrointestinal tract (GI PEComas) are exceedingly rare, with only a limited number of published reports worldwide. Given the scarcity of GI PEComas and their relatively short follow-up periods, our current knowledge of their biologic behavior, molecular genetic alterations, diagnostic criteria, and prognostic factors continues to be very limited.We present 2 cases of GI PEComas, one of which showed an aggressive histologic behavior that underwent multiple combined chemotherapies. We also review the available English-language medical literature on GI PEComas-not otherwise specified (PEComas-NOS) and discuss their clinicopathological and molecular genetic features.Pathologic analyses including histomorphologic, immunohistochemical, and ultrastructural studies were performed to evaluate the clinicopathological features of GI PEComas, their diagnosis, and differential diagnosis. Immunohistochemistry, semiquantitative reverse transcriptase polymerase chain reaction, and DNA sequencing assays were carried out to detect the potential molecular genetic alterations in our cases. Microscopically, the tumors showed distinctive histologic features of PEComas-NOS, including fascicular or nested architecture, epithelioid or spindled cell type, and clear to eosinophilic cytoplasm. The tumor cells were immunohistochemically positive for melanocytic markers. Molecular pathological assays confirmed a PSF-TFE3 gene fusion in one of our cases. Furthermore, in this case microphthalmia-associated transcription factor and its downstream genes were found to exhibit elevated transcript levels.Knowledge about the molecular genetic alterations in GI PEComas is still limited and warrants further study.

A genetic variation of the p38ß promoter region is correlated with an increased risk of sporadic colorectal cancer.

p38 plays a critical role in the proliferation, survival, migration and metastasis of colorectal cancer (CRC) cells. The present study assessed the correlation between a single nucleotide polymorphism (SNP) in the p38ß promoter region (rs2235356, -1628A>G) and the predisposition of individuals to sporadic CRC in a case-control study. A genotyping method was developed to detect this SNP, using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis. A logistic regression analysis was used to determine the odds ratio (OR) and 95% confidence interval (CI). It was revealed that the -1628G variant allele was correlated with an increased risk of CRC (OR, 1.99; 95% CI, 1.60-2.47; P<0.0001). An in silico analysis revealed several transcription factors that either acquired or lost the ability to bind to -1628AA in the p38ß promoter region due to the SNP. Therefore, this allelic variant may be a genetic modifier for CRC susceptibility.

Snail promotes lymph node metastasis and Twist enhances tumor deposit formation through epithelial-mesenchymal transition in colorectal cancer.

Snail and Twist, transcriptional repressors of E-cadherin as well as inducers of epithelial-mesenchymal transition, play pivotal roles in tumor invasion and metastasis. We investigated the expression of Snail, Twist, and E-cadherin by immunohistochemistry in 193 colorectal cancers, including 79 with positive lymph nodes, 36 with tumor deposits, 39 with both, and 39 with no metastases. Snail was expressed to a greater extent in the group with positive lymph nodes (68.4%), whereas Twist was overexpressed in patients with other metastases (75.0%). Ectopic expression of Snail and Twist correlated with reduced membranous expression of E-cadherin. Importantly, Snail overexpression correlated significantly with lymph node metastasis (P < .0001), whereas Twist up-regulation correlated strongly with other metastases (P < .0001). Multivariate logistic regression analysis showed that Snail was an independent predictor of lymph node metastasis (odds ratio, 4.445; 95% confidence interval, 2.250-8.781; P < .0001), whereas Twist displayed predictive value for metastasis formation (odds ratio, 5.606; 95% confidence interval, 2.829-11.111; P < .0001), suggesting that lymph node and other metastases may follow different signaling pathways. In conclusion, ectopic expression of Snail and Twist contributed to lymph node and disseminated metastasis, respectively, by reducing E-cadherin expression, providing a novel role for Snail and Twist in the progression of colorectal cancer.

NFκB1 and NFκBIA polymorphisms are associated with increased risk for sporadic colorectal cancer in a southern Chinese population.

BACKGROUND: Nuclear factor κB (NFκB) plays a key role in the regulation of apoptosis. The function of NFκB is inhibited by binding to NFκB inhibitor (IκB), and disruption of the balance of NFκB and IκB is related to the development of many diseases, including tumors. Therefore, we hypothesized that the NFκB1 (-94del/insATTG) and NFκBIA (2758 A>G) polymorphisms were associated with colorectal cancer (CRC) susceptibility. METHODS: In a hospital-based case-control study of 1001 CRC patients and 1005 cancer-free controls frequency matched by age and sex, we genotyped polymorphisms using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method and performed luciferase assays and Western blotting analysis to identify whether genetic variants in NFκBIA alter its gene expressions and functions and thus cancer risk. RESULTS: We found that both NFκB1-94 ins/delATTG and NFκBIA 2758 A>G polymorphisms were correlated with CRC risk (OR = 1.47; 95%CI = 1.14-1.86, and OR = 1.38; 95% CI = 1.14-1.66, respectively). Furthermore, when evaluated these two polymorphisms together, the combined genotypes with 2 variant (risk) alleles (2758GG and -94ins/ins+del/ins) were associated with an increased risk of CRC (OR = 1.71; 95% CI = 1.23-2.38) compared to 0 variant, and the significant trend for 2 variant (risk) alleles were more pronounced among subgroups of aged <60 years, women, never drinkers, never smokers, persons with a normal BMI and those with a family history of cancer(P(trend)<0.01). Moreover, luciferase assays showed that the G allele in the 3'UTR significantly decreased NFκBIA mRNA stability and the A allele regulation by miRNA449a in vitro and that the NFκBIA protein expression levels of the AA+AG variant carriers were significantly higher in peritumoral tissues than those of the 2758GG genotype. CONCLUSION: NFκB1 and NFκBIA polymorphisms appear to jointly contribute to risk of CRC. These two variants may be a genetic modifier for CRC susceptibility in this southern Chinese population.