Hacking cell differentiation: transcriptional rerouting in reprogramming, lineage infidelity and metaplasia

Initiating neoplastic cell transformation events are of paramount importance for the comprehension of regeneration and vanguard oncogenic processes but are difficult to characterize and frequently clinically overlooked. In epithelia, pre-neoplastic transformation stages are often distinguished by the appearance of phenotypic features of another differentiated tissue, termed metaplasia. In haemato/lymphopoietic malignancies, cell lineage ambiguity is increasingly recorded. Both, metaplasia and biphenotypic leukaemia/lymphoma represent examples of dysregulated cell differentiation that reflect a history of trans-differentiation and/or epigenetic reprogramming. Here we compare the similarity between molecular events of experimental cell trans-differentiation as an emerging therapeutic concept, with lineage confusion, as in metaplasia and dysplasia forecasting tumour development.

Tumor necrosis factor alpha extended haplotypes and risk of gastric carcinoma

The tumor necrosis factor alpha (TNFA)-308*A allele has been found to confer an increased risk of gastric carcinoma. Inconsistency in risk estimates across populations lead us to hypothesize about the presence of an alternative causal locus in the same chromosomal region. A suitable approach is to determine the tumor necrosis factor haplotypic structure in order to clarify whether the association between the *A allele and the increased risk of gastric carcinoma is etiologic or secondary to linkage disequilibrium. Firstly, we assessed the association between the TNFA-308G>A polymorphism and the risk of gastric carcinoma in a population from Northern Portugal (508 gastric carcinoma patients, 713 controls); secondly, we genotyped five microsatellite loci (TNFa, b, c, d, e) flanking the TNFA-308G>A locus to establish the haplotypic structure associated with this single-nucleotide polymorphism in cases (122 patients) and controls (169 individuals). We found a significant association between the *A allele and increased risk of gastric carcinoma (odds ratio, 1.7; 95% confidence interval, 1.3-2.2) confirming previous results in our population. Regarding the *A allele-associated haplotypes, the most relevant difference was found for the H1A haplotype present in 33.1% of the cases and 12.5% of the controls. We also observed haplotypes associated with the *A allele that were found only in cases or controls. A population differentiation test showed that the gastric carcinoma and the control groups were significantly different for the *A allele haplotypic structure. This suggests that the association between the TNFA-308G>A polymorphism and increased risk of gastric carcinoma is dependent on linkage disequilibrium with an as yet unidentified locus.

C/EBPbeta is over-expressed in gastric carcinogenesis and is associated with COX-2 expression

The CCAAT/enhancer-binding protein beta (C/EBPbeta) transcription factor has been associated with several cancer models. In this study, the expression of C/EBPbeta was analysed in a series of 90 gastric carcinomas (GCs). We also assessed the effect of C/EBPbeta on COX-2 expression. In normal gastric mucosa, C/EBPbeta expression was restricted to cells in the proliferative zone. In intestinal metaplasia, dysplasia, and GC of the intestinal and atypical subtypes, C/EBPbeta was over-expressed (p < 0.0001, for the association with histological type). C/EBPbeta and Ki67, a marker of cell proliferation, were also co-expressed in primary GC. We also observed an overlap between C/EBPbeta and COX-2 expression in GC. Using GC cell lines we show that C/EBPbeta can regulate the expression of endogenous COX-2 and transactivate the promoter of the COX-2 gene, depending on its methylation status. These results suggest that C/EBPbeta may be a marker of neoplastic transformation and also play an active role in gastric tumourigenesis by regulating COX-2 expression.

Trefoil factors: from ulceration to neoplasia

There is convincing evidence that trefoil factors (TFFs) do play an important role in tumourigenesis. However, their specific roles in cancer are not yet clear. Recently, TFFs have been shown to interfere with crucial biological processes such as cell proliferation, differentiation, apoptosis and angiogenesis. Research on the function of TFFs and its relationship with specific signal transduction pathways has also advanced significantly. As a consequence, some ideas about the role of TFFs in cancer have started to take shape. The objective of this review is to summarize and discuss current knowledge on the relationship between TFFs and cancer.

NOD2/CARD15 and TNFA, but not IL1B and IL1RN, are associated with Crohn's disease

BACKGROUND

NOD2/CARD15 was described as the first susceptibility gene to Crohn's disease (CD). Polymorphisms in the TNFA gene and in the IL1 gene cluster, which are associated with an enhanced chronic inflammatory response, may also play a role in the development of CD. The aim of this study was to determine the association of polymorphisms in the CARD15, TNFA, IL1B, and IL1RN genes with risk of development of CD and with the clinicopathological profile of CD patients.

METHODS

In a case-control study including 235 CD patients and 312 controls (929 controls for TNFA genotyping), the CARD15 (R702W, G908R, and 1007fs), TNFA (-308G/A and -857C/T), IL1B (-511C/T), and IL1RN (intron 2 variable number of tandem repeats) polymorphisms were genotyped.

RESULTS

We observed a significant association between CD and the CARD15 polymorphisms, with an odds ratio (OR) of 2.9 [95% confidence interval (CI), 1.9 to 4.6] for carriers of 1 variant allele and an OR of 11.8 (95% CI, 3.5 to 40.4) for carriers of 2 variant alleles. Patients with CARD15 polymorphisms had more frequently ileal or ileocolonic disease location, stricturing phenotype, abdominal surgery, and no extraintestinal manifestations. The TNFA-308A/A genotype was associated with susceptibility to CD with an OR of 3.0 (95% CI, 1.2 to 7.2). TNFA-308A/A homozygotes showed a higher frequency of erythema nodosum and arthritis, colonic disease location, and absence of abdominal surgery. No associations were found with the TNFA-857, IL1B-511, and the IL1RN VNTR polymorphisms.

CONCLUSIONS

These findings suggest that CARD15 and TNFA-308 genetic polymorphisms are associated with increased risk of CD displaying distinct clinicopathological profiles.