| 1. |
- Aleksandrova, Krasimira, et al.
(författare)
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Total and high-molecular-weight adiponectin and risk of colorectal cancer : the European prospective investigation into cancer and nutrition study
- 2012
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Ingår i: Carcinogenesis. - : Oxford University Press (OUP). - 0143-3334 .- 1460-2180. ; 33:6, s. 1211-1218
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Tidskriftsartikel (refereegranskat)abstract
- Adiponectin - an adipose-tissue-derived protein may provide a molecular link between obesity and colorectal cancer (CRC), but evidence from large prospective studies is limited. In particular, no epidemiological study explored high-molecular-weight (HMW) and non-HMW adiponectin fractions in relation to CRC risk, despite they were hypothesised to have differential biological activities, i.e. regulating insulin sensitivity (HMW-adiponectin) versus inflammatory response (non-HMW-adiponectin). In a prospective nested case-control study we investigated whether pre-diagnostic serum concentrations of total, HMW and non-HMW-adiponectin are associated with risk of CRC, independent of obesity and other known CRC risk factors. A total of 1206 incident cases (755 colon, 451 rectal) were matched to 1206 controls using incidence density sampling. In conditional logistic regression, adjusted for dietary and lifestyle factors, total adiponectin and non-HMW-adiponectin concentrations were inversely associated with risk of CRC [relative risk (RR) comparing highest versus lowest quintile = 0.71, 95% confidence interval (CI) = 0.53-0.95, P (trend)=0.03 for total adiponectin and 0.45, 95%CI=0.34-0.61, P (trend)<0.0001 for non-HMW-adiponectin]. HMW-adiponectin concentrations were not associated with CRC risk (RR=0.91, 95%CI=0.68-1.22, P (trend)=0.55). Non-HMW-adiponectin was associated with CRC risk even after adjustment for body mass index and waist circumference (RR=0.39, 95%CI=0.26-0.60, P (trend)<0.0001); whereas the association with total adiponectin was no longer significant (RR=0.81, 95%CI=0.60-1.09, P (trend)=0.23). When stratified by cancer site, non-HMW-adiponectin was inversely associated with both colon and rectal cancer. These findings suggest an important role of the relative proportion of non-HMW-adiponectin in CRC pathogenesis. Future studies are warranted to confirm these results and to elucidate the underlying mechanisms.
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| 2. |
- Aydoğdu, Eylem, et al.
(författare)
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MicroRNA-regulated gene networks during mammary cell differentiation are associated with breast cancer.
- 2012
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Ingår i: Carcinogenesis. - : Oxford University Press (OUP). - 0143-3334 .- 1460-2180. ; 33:8, s. 1502-11
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Tidskriftsartikel (refereegranskat)abstract
- MicroRNAs (miRNAs) play pivotal roles in stem cell biology, differentiation and oncogenesis and are of high interest as potential breast cancer therapeutics. However, their expression and function during normal mammary differentiation and in breast cancer remain to be elucidated. In order to identify which miRNAs are involved in mammary differentiation, we thoroughly investigated miRNA expression during functional differentiation of undifferentiated, stem cell-like, murine mammary cells using two different large-scale approaches followed by qPCR. Significant changes in expression of 21 miRNAs were observed in repeated rounds of mammary cell differentiation. The majority, including the miR-200 family and known tumor suppressor miRNAs, was upregulated during differentiation. Only four miRNAs, including oncomiR miR-17, were downregulated. Pathway analysis indicated complex interactions between regulated miRNA clusters and major pathways involved in differentiation, proliferation and stem cell maintenance. Comparisons with human breast cancer tumors showed the gene profile from the undifferentiated, stem-like stage clustered with that of poor-prognosis breast cancer. A common nominator in these groups was the E2F pathway, which was overrepresented among genes targeted by the differentiation-induced miRNAs. A subset of miRNAs could further discriminate between human non-cancer and breast cancer cell lines, and miR-200a/miR-200b, miR-146b and miR-148a were specifically downregulated in triple-negative breast cancer cells. We show that miR-200a/miR-200b can inhibit epithelial-mesenchymal transition (EMT)-characteristic morphological changes in undifferentiated, non-tumorigenic mammary cells. Our studies propose EphA2 as a novel and important target gene for miR-200a. In conclusion, we present evidentiary data on how miRNAs are involved in mammary cell differentiation and indicate their related roles in breast cancer.
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| 3. |
- Dahlman-Wright, Karin, et al.
(författare)
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Interplay between AP-1 and estrogen receptor α in regulating gene expression and proliferation networks in breast cancer cells
- 2012
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Ingår i: Carcinogenesis. - : Oxford University Press (OUP). - 0143-3334 .- 1460-2180. ; 33:9, s. 1684-91
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Tidskriftsartikel (refereegranskat)abstract
- Estrogen receptor α (ERα) is a ligand-dependent transcription factor that plays an important role in breast cancer. Estrogen-dependent gene regulation by ERα can be mediated by interaction with other DNA-binding proteins, such as activator protein-1 (AP-1). The nature of such interactions in mediating the estrogen response in breast cancer cells remains unclear. Here we show that knockdown of c-Fos, a component of the transcription factor AP-1, attenuates the expression of 37% of all estrogen-regulated genes, suggesting that c-Fos is a fundamental factor for ERα-mediated transcription. Additionally, knockdown of c-Fos affected the expression of a number of genes that were not regulated by estrogen. Pathway analysis reveals that silencing of c-Fos downregulates an E2F1-dependent proproliferative gene network. Thus, modulation of the E2F1 pathway by c-Fos represents a novel mechanism by which c-Fos enhances breast cancer cell proliferation. Furthermore, we show that c-Fos and ERα can cooperate in regulating E2F1 gene expression by binding to regulatory elements in the E2F1 promoter. To start to dissect the molecular details of the cross talk between AP-1 and estrogen signaling, we identify a novel ERα/AP-1 target, PKIB (cAMP-dependent protein kinase inhibitor-β), which is overexpressed in ERα-positive breast cancer tissues. Knockdown of PKIB results in robust growth suppression of breast cancer cells. Collectively, our findings support c-Fos as a critical factor that governs estrogen-dependent gene expression and breast cancer proliferation programs.
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| 4. |
- Duell, Eric J., et al.
(författare)
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Genetic variation in alcohol dehydrogenase (ADH1A, ADH1B, ADH1C, ADH7) and aldehyde dehydrogenase (ALDH2), alcohol consumption and gastric cancer risk in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort
- 2012
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Ingår i: Carcinogenesis. - Oxford : Oxford University Press (OUP). - 0143-3334 .- 1460-2180. ; 33:2, s. 361-367
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Tidskriftsartikel (refereegranskat)abstract
- Studies that have examined the association between alcohol consumption and gastric cancer (GC) risk have been inconsistent. We conducted an investigation of 29 genetic variants in alcohol metabolism loci (alcohol dehydrogenase, ADH1 gene cluster: ADH1A, ADH1B and ADH1C; ADH7 and aldehyde dehydrogenase, ALDH2), alcohol intake and GC risk. We analyzed data from a nested case-control study (364 cases and 1272 controls) within the European Prospective Investigation into Cancer and Nutrition cohort. Single nucleotide polymorphisms (SNPs) were genotyped using a customized array. We observed a statistically significant association between a common 3'-flanking SNP near ADH1A (rs1230025) and GC risk [allelic odds ratio (OR)(A v T) = 1.30, 95% confidence interval (CI) = 1.07-1.59]. Two intronic variants, one in ADH1C (rs283411) and one in ALDH2 (rs16941667), also were associated with GC risk (ORT v C = 0.59; 95% CI = 0.38-0.91 and ORT v C = 1.34; 95% CI = 1.00-1.79, respectively). Individuals carrying variant alleles at both ADH1 (rs1230025) and ALDH2 (rs16941667) were twice as likely to develop GC (ORA+T = 2.0; 95% CI = 1.25-3.20) as those not carrying variant alleles. The association between rs1230025 and GC was modified by alcohol intake (< 5 g/day: ORA = 0.89, 95% CI = 0.57-1.39; >= 5 g/day: ORA = 1.45, 95% CI = 1.08-1.94, P-value = 0.05). The association was also modified by ethanol intake from beer. A known functional SNP in ADH1B (rs1229984) was associated with alcohol intake (P-value = 0.04) but not GC risk. Variants in ADH7 were not associated with alcohol intake or GC risk. In conclusion, genetic variants at ADH1 and ALDH2 loci may influence GC risk, and alcohol intake may further modify the effect of ADH1 rs1230025. Additional population-based studies are needed to confirm our results.
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| 5. |
- Li, Donghui, et al.
(författare)
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Pathway analysis of genome-wide association study data highlights pancreatic development genes as susceptibility factors for pancreatic cancer
- 2012
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Ingår i: Carcinogenesis. - : Oxford University Press. - 0143-3334 .- 1460-2180. ; 33:7, s. 1384-1390
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Tidskriftsartikel (refereegranskat)abstract
- Four loci have been associated with pancreatic cancer through genome-wide association studies (GWAS). Pathway-based analysis of GWAS data is a complementary approach to identify groups of genes or biological pathways enriched with disease-associated single-nucleotide polymorphisms (SNPs) whose individual effect sizes may be too small to be detected by standard single-locus methods. We used the adaptive rank truncated product method in a pathway-based analysis of GWAS data from 3851 pancreatic cancer cases and 3934 control participants pooled from 12 cohort studies and 8 case-control studies (PanScan). We compiled 23 biological pathways hypothesized to be relevant to pancreatic cancer and observed a nominal association between pancreatic cancer and five pathways (P < 0.05), i.e. pancreatic development, Helicobacter pylori lacto/neolacto, hedgehog, Th1/Th2 immune response and apoptosis (P = 2.0 x 10(-6), 1.6 x 10(-5), 0.0019, 0.019 and 0.023, respectively). After excluding previously identified genes from the original GWAS in three pathways (NR5A2, ABO and SHH), the pancreatic development pathway remained significant (P = 8.3 x 10(-5)), whereas the others did not. The most significant genes (P < 0.01) in the five pathways were NR5A2, HNF1A, HNF4G and PDX1 for pancreatic development; ABO for H.pylori lacto/neolacto; SHH for hedgehog; TGFBR2 and CCL18 for Th1/Th2 immune response and MAPK8 and BCL2L11 for apoptosis. Our results provide a link between inherited variation in genes important for pancreatic development and cancer and show that pathway-based approaches to analysis of GWAS data can yield important insights into the collective role of genetic risk variants in cancer.
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| 6. |
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| 7. |
- Nagalingam, Arumugam, et al.
(författare)
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Med1 plays a critical role in the development of tamoxifen resistance
- 2012
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Ingår i: Carcinogenesis. - : Oxford University Press (OUP). - 0143-3334 .- 1460-2180. ; 33:4, s. 918-930
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the molecular pathways that contribute to the development of tamoxifen resistance is a critical research priority as acquired tamoxifen resistance is the principal cause of poor prognosis and death of patients with originally good prognosis hormone-responsive breast tumors. In this report, we provide evidence that Med1, an important subunit of mediator coactivator complex, is spontaneously upregulated during acquired tamoxifen-resistance development potentiating agonist activities of tamoxifen. Phosphorylated Med1 and estrogen receptor (ER) are abundant in tamoxifen-resistant breast cancer cells due to persistent activation of extracellular signal-regulated kinases. Mechanistically, phosphorylated Med1 exhibits nuclear accumulation, increased interaction with ER and higher tamoxifen-induced recruitment to ER-responsive promoters, which is abrogated by inhibition of Med1 phosphorylation. Stable knockdown of Med1 in tamoxifen-resistant cells not only reverses tamoxifen resistance in vitro but also in vivo. Finally, higher expression levels of Med1 in the tumor significantly correlated with tamoxifen resistance in ER-positive breast cancer patients on adjuvant tamoxifen monotherapy. In silico analysis of breast cancer, utilizing published profiling studies showed that Med1 is overexpressed in aggressive subsets. These findings provide what we believe is the first evidence for a critical role for Med1 in tamoxifen resistance and identify this coactivator protein as an essential effector of the tamoxifen-induced breast cancer growth.
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| 8. |
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| 9. |
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| 10. |
- Ungerbäck, Jonas, et al.
(författare)
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Genetic variation and alterations of genes involved in NFκB/TNFAIP3- and NLRP3-inflammasome signaling affect susceptibility and outcome of colorectal cancer
- 2012
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Ingår i: Carcinogenesis. - Oxford, United kingdom : Oxford University Press. - 0143-3334 .- 1460-2180. ; 33:11, s. 2126-2134
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Tidskriftsartikel (refereegranskat)abstract
- Colorectal tumors are continuously exposed to an inflammatory environment, which together with mitogenic signals sustain several cancer hallmarks. Nuclear factor-kappa B (NFκB) is a major regulator of inflammation and variation in NFκB-associated genes could potentially be used as biomarkers to identify patients with increased risk of colorectal cancer (CRC) development, and/or a rapidly progressing disease. In this study, 348 CRC cases and 806 randomly selected healthy individuals from southeastern Sweden were examined with regard to seven polymorphisms in NFκB pathway-associated genes. Log-rank-tests and Cox proportional hazard regression analysis examined the association between the polymorphisms and CRC-specific survival, whereas chi-square tests and logistic regression analysis were used to test for associations between the polymorphisms and CRC susceptibility. Gene expression and loss of heterozygosity analyses of TNFAIP3 were carried out in a subset of tumors to assess its role as a tumor suppressor in CRC. Heterozygous and polymorphic TNFAIP3 (rs6920220), heterozygous NLRP3 (Q705K) and polymorphic NFκB -94 ATTG ins/del genotypes were found to be associated with poorer survival in patients diagnosed with invasive CRC (aHR = 5.2, 95% CI: 2.5-10.9, P < 0.001). TNFAIP3 mRNA levels were significantly decreased in tumors compared with adjacent non-neoplastic mucosa (P < 0.0001) and loss of heterozygosity of 6q23.3 (TNFAIP3) was detected in 17% of cases, whereas only 2.5% of the investigated specimens displayed TNFAIP3 gene mutations. We propose that TNFAIP3 (rs6920220), NLRP3 (Q705K) and NFκB -94 ATTG ins/del polymorphisms are associated with poor survival in patients with advanced CRC and may be used as prognostic markers. Experimental results indicate that TNFAIP3 may act as a tumor suppressor in CRC.
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