Epigenetic modifications but not genetic polymorphisms regulate KEAP1 expression in colorectal cancer.

Kelch-like ECH-associated protein 1 (KEAP1), as a negative regulator of nuclear factor erythroid 2 like 2 ( NRF2), plays a pivotal role in NRF2 signaling pathway and involves in tumorigenesis. Polymorphisms and methylation in gene promoter region may influence its expression and be related to cancer susceptibility. In this study, we examined the effect of the KEAP1-NRF2 interaction on the risk of colorectal cancer (CRC). The polymorphisms of NRF2 and KEAP1 were genotyped using the improved multiplex ligase detection reaction assay. KEAP1 promoter methylation and histone modification were analyzed using bisulfite genome sequencing and chromatin immunoprecipitation (ChIP) assay, respectively. The KEAP1 rs1048290 CC genotype and C allele were associated with increased risks of CRC (CC vs GG: odds ratio [OR] = 1.39; 95% confidence interval [CI], 1.08-1.78; CC vs GG/GC: OR = 1.29; 95% CI, 1.05-1.58; C vs G: OR = 1.18; 95% CI, 1.04-1.34). The rs1048290-rs11545829 GT haplotype was associated with a reduced risk of CRC. KEAP1-NRF2 interaction analysis revealed that the rs6721961, rs35652124, rs1048290, and rs11545829 conferred the susceptibility to CRC. The hypermethylation of KEAP1 promoter resulted in lower levels of KEAP1 messenger RNA (mRNA). After treatment with 5-aza-2'-deoxycytidine/trichostatin A, KEAP1 promoter methylation was decreased and KEAP1 mRNA levels were increased. ChIP-quantitative polymerase chain reaction results showed an enhanced enrichment of H3K4Me3 and H3K27Ac to the promoter of KEAP1. In vitro methylation analysis showed that the methylated plasmid decreased the transcriptional activity by 70%-84%. These findings suggest that the KEAP1- NRF2 pathway could potentially impact CRC risk and the downregulation of KEAP1 could be explained in part by epigenetic modifications.

Long Noncoding RNA AB074169 Inhibits Cell Proliferation via Modulation of KHSRP-Mediated CDKN1a Expression in Papillary Thyroid Carcinoma.

Long noncoding RNAs (lncRNA) are emerging as a novel class of regulators in gene expression associated with tumorigenesis. However, the role of lncRNAs in papillary thyroid carcinoma (PTC) is poorly understood. Here, we conducted global lncRNA profiling and identified lncRNA AB074169 (lncAB) as significantly downregulated in PTC. Decreased expression of lncAB in PTC was caused by CpG hypermethylation within its gene promoter. Functional studies showed that lncAB overexpression led to cell-cycle arrest and tumor growth inhibition in vitro and in vivo, whereas lncAB knockdown promoted cell proliferation. Mechanistic analyses revealed that lncAB bound KH-type splicing regulatory protein (KHSRP) and also decreased expression of KHSRP, thus increasing CDKN1a (p21) expression and decreasing CDK2 expression to repress cell proliferation. Taken together, these findings demonstrate that lncAB functions as a tumor suppressor during PTC tumorigenesis.Significance: These findings identify a tumor-suppressive long noncoding RNA in papillary thyroid carcinoma.Graphical Abstract: http://cancerres.aacrjournals.org/content/canres/78/15/4163/F1.large.jpg Cancer Res; 78(15); 4163-74. ©2018 AACR.

Functional polymorphisms in the promoter region of miR-17-92 cluster are associated with a decreased risk of colorectal cancer.

miR-17-92 cluster is identified as a potential oncogenic miRNA. The aim of this study was to investigate the association of polymorphisms in the promoter region of miR-17-92 cluster with the risk of colorectal cancer (CRC). Three polymorphisms (i.e., rs9588884, rs982873 and rs1813389) in the promoter of miR-17-92 were analyzed among 874 cases and 1132 controls using a TaqMan allelic discrimination assay or a polymerase chain reaction-restriction fragment length polymorphism method. Relative expression of miR-17-92 was examined among CRC tumors and noncancerous tissues using quantitative reverse transcription-PCR. Transcriptional activities were measured using dual-luciferase reporter assay. We found a significantly reduced CRC risk with the rs9588884 (GG vs. CC: adjusted OR = 0.46, 95% CI, 0.35-0.62; dominant model: adjusted OR = 0.72, 95% CI, 0.59-0.86; recessive model: adjusted OR = 0.53, 95% CI, 0.40-0.69) and the rs982873 (CC vs. TT: adjusted OR = 0.60, 95%CI, 0.46-0.80; recessive model: adjusted OR = 0.62, 95% CI, 0.49-0.80). Haplotype analysis showed that the GCG haplotype had a decreased risk for CRC compared to the CTA haplotype (adjusted OR = 0.67, 95% CI, 0.57-0.79). The rs9588884 GG displayed a lower level of miR-20a and the rs982873 CC displayed a lower level of miR-17. Additionally, the rare allele of rs9588884 G and the rs982873 C revealed a reduced luciferase activity. These findings indicate that the rs9588884 GG and the rs982873 CC in the promoter of miR-17-92 may protect against CRC, possibly by decreasing transcriptional activity and eventually resulting in lower levels of miR-20a and miR-17.

Association between IL-27 gene polymorphisms and risk of papillary thyroid carcinoma.

AIM: IL-27 has potent antitumor effects. We aimed to examine the contribution of single nucleotide polymorphisms in IL-27 to the risk of papillary thyroid carcinoma (PTC). MATERIALS & METHODS:  IL-27 rs153109 and rs17855750 were analyzed in 496 PTC patients and 629 controls, using a polymerase chain reaction-restriction fragment length polymorphism method. RESULTS: The rs153109 AG and AG/GG genotypes were significantly associated with increased risks for PTC. Significantly increased PTC risk was also associated with rs17855750 GT and GT/GG genotypes. Combined genotypes of rs153109 AG/GG and rs17855750 GT/GG increased the risk of PTC (p < 0.05). CONCLUSION: These findings showed that IL-27 rs153109 and rs17855750 might be related to the tumorigenesis of PTC.

A polymorphism rs4705341 in the flanking region of miR-143/145 predicts risk and prognosis of colorectal cancer.

The aim of this study was to investigate the effect of a polymorphism rs4705341 in the flanking region of miR-143/145 on the risk of colorectal cancer (CRC). The rs4705341 polymorphism was analyzed in 1002 cases and 1062 controls using a polymerase chain reaction-restriction fragment length polymorphism method. We found a significantly reduced CRC susceptibility with miR-143/145 rs4705341 in homozygote comparison (adjusted OR = 0.66, 95%CI, 0.50-0.88, P = 0.004), dominant genetic model (adjusted OR = 0.80, 95%CI, 0.67-0.96, P = 0.015), recessive genetic model (adjusted OR = 0.73, 95%CI, 0.56-0.94, P = 0.016), and allele comparison (adjusted OR = 0.83, 95%CI, 0.73-0.94, P = 0.004). Stratification analysis showed that the rs4705341 was related to differentiated status, clinical stage I-II, and patients without lymph node metastasis. Moreover, patients with rs4705341GG had a longer overall survival (adjusted HR = 5.57, 95%CI, 0.95-32.68). These findings indicate that the miR-143/145 rs4705341 may be used as a potential biomarker for the development and prognosis of CRC.

Seroprevalence and genotype of Toxoplasma gondii in pigs, dogs and cats from Guizhou province, Southwest China.

BACKGROUND: Toxoplasma gondii is an obligate, intracellular protozoan that infects almost all warm-blooded animals, including humans, domesticated and wild animals. Recent studies of Toxoplasma gondii isolates from animals in different regions of China have shown a limited genetic diversity with the dominance of the ToxoDB PCR-RFLP genotype #9 named as "Chinese 1". However, there is not much published information regarding its prevalence in domestic animals from Guizhou province, a subtropical region in Southwest China. The objectives of this study were to determine seroprevalence and genetic diversity of T .gondii in pigs, dogs and cats in Guizhou province, Southwest China. FINDINGS: The anti-T. gondii IgG were detected in 70.0%(49/70) pigs, 20.56%(22/107) dogs and 63.16(12/19) cats. The anti-T. gondii IgM were found in 0.93%(1/107) dogs, 21.53%(4/19) cats, but not in pigs. In addition, the toxoplasma circulating antigen (CAG) were detected in 16.9%18/70)pigs, 13.1% (14/107) dogs and 10.5%(2/19) cats. The T. gondii DNA were detected in 31.5%(22/70) pigs, 3.7%(4/107) dogs and 52.63%(10/19) cats. Five T. gondii isolates were obtained(3 from pigs and 2 from cats). The genotype of these five isolates belonged to the predominant genotype "Chinese 1". CONCLUSIONS: The high prevalence of T. gondii infection in pigs,cats and dogs indicated that the T. gondii infection is common in Guizhou province. Additionally, the T. gondii genotype "Chinese 1" was dominant in Southwest China.

A Functional Polymorphism in the Promoter of MiR-143/145 Is Associated With the Risk of Cervical Squamous Cell Carcinoma in Chinese Women: A Case-Control Study.

MiR-143/145 is down-regulated in cervical cancer, which may serve as a tumor suppressor by targeting KRAS and Ras-responsive element-binding protein (RREB1). Activated KRAS leads to down-regulation of miR-143/145 transcription in a RREB1-dependent manner, establishing a miR-143/145-KRAS-RREB1 feedback loop. A polymorphism rs4705343C/T in the promoter of miR-143/145 might influence the binding of TATA-binding protein. We hypothesized that the miR-143/145 rs4705343 and KRAS rs712 may be related to the occurrence of cervical squamous cell carcinoma (CSCC). In this study, we genotyped the 2 polymorphisms in 415 patients with CSCC and 504 controls using polymerase chain reaction-restriction fragment length polymorphism. The promoter activities were measured by the Dual-Luciferase Reporter Assay System. We found that the rs4705343TC genotype was associated with an increased risk of CSCC (adjusted odds ratio [OR] = 1.37; 95% confidence interval [CI], 1.05-1.80). The significantly increased association was also observed in a dominant genetic model (adjusted OR = 1.32; 95% CI, 1.01-1.72). Combined analysis showed that individuals carrying the genotypes of rs4705343 TC/CC and rs712GT/TT had a 1.47-fold increased risk of CSCC (adjusted OR = 1.47; 95% CI, 1.01-2.15). By using multifactor dimensionality reduction software method, we identified a significant interaction between the miR-143/145 rs4705343 and KRAS rs712. Dual-Luciferase Reporter Assay showed that the luciferase activity was significantly lower in cells transfected with the rs4705343C allele than that of the rs4705343T allele. These findings indicate that miR-143/145 rs4705343 and KRAS rs712 may contribute to the etiology of CSCC in Chinese women.

Association between a functional polymorphism rs712 within let-7-binding site and risk of papillary thyroid cancer.

KRAS mutation is frequently detected in a series of cancers, including papillary thyroid cancer (PTC). Recently, a genetic variant of rs712 in the 3' untranslated region of the KRAS gene has been reported to be functional in the regulation of KRAS by disrupting complementary site of let-7 and miR-181. We aimed to investigate whether the polymorphism is a risk factor for PTC. We conducted an association study, including 252 PTC patients and 290 healthy controls. The KRAS rs712 polymorphism was genotyped by polymerase chain reaction-restriction fragment length polymorphism. Although no significant difference of the KRAS rs712 distribution was observed between cases and controls in overall analysis, stratification analysis showed that patients carrying the KRAS rs712TT genotype were less likely to develop stages T3 and T4 under a recessive genetic model (OR 0.26, 95% CI 0.08-0.82). These results supported the role of the KRAS rs712 polymorphism as a potential genetic biomarker for the extension of PTC. Further population-based association studies are of great value to confirm the results in diverse ethnicities.