Estrogen-responsive RING finger mRNA induction in gastrointestinal carcinoma cells following bile acid treatment

The role of the gallbladder in humans

The basic function of the gallbladder in humans is one of protection. The accumulation of the primary bile acids (cholic acid and chenodeoxycholic acid) in the gallbladder reduces the formation of the secondary bile acids (deoxycholic acid and lithocholic acid), thus diminishing their concentration in the so-called gallbladder-independent enterohepatic circulation and protecting the liver, the stomach mucosa, the gallbladder, and the colon from their toxic hydrophobic effects. The presence or absence of the gallbladder in mammals is a determining factor in the synthesis of hydrophobic or hydrophilic bile acids. Because the gallbladder contracts 5-20 min after food is in the stomach and the "gastric chyme" moves from the stomach to the duodenum 1-3 h later, the function of the gallbladder bile in digestion may be insignificant. The aim of this article was to provide a detailed review of the role of the gallbladder and the mechanisms related to bile formation in humans.

Bile acids mimic oxidative stress induced upregulation of thioredoxin reductase in colon cancer cell lines

Bile acids have been suggested to play an important role in the etiology of colon and gastric cancer after gastrectomy, but the molecular biology of these effects is poorly understood. We evaluated the effect of different bile acids on human gastric and colon carcinoma cells and identified genes by RNA arbitrarily primed PCR for differential display that are modulated following treatment with hydrophobic bile acids. Thioredoxin reductase (TR) mRNA was upregulated after treatment with taurochenodeoxycholic acid (TCDCA) in St 23132 cells. This raised the question whether deoxycholic acid (DCA) would have regulative effects on TR in HT-29 cells. After an incubation time of 6 h with DCA, TR mRNA expression was increased up to threefold. Ursodeoxycholic acid had no influence on TR mRNA expression. The upregulation of TR after DCA incubation was almost identical to incubation with 12-O-tetradecanoylphorbol-13-acetate. This implies that hydrophobic bile acids mediate oxidative stress in gastrointestinal cancer cells, which was confirmed by measurement of oxidative burst after treatment with DCA. The results suggest that hydrophobic bile acids induce oxidative stress in gastrointestinal cancer resulting in a compensatory upregulation of TR mRNA, one of the key components in the complex anti-oxidant defense system within eukaryotic cells. The activation of at least parts of the redox signaling system is potentially related to the cytotoxicity and the stimulation of the cell death machinery induced by toxic bile acids.

Use of simplified transcriptors for the analysis of gene expression profiles in laser-microdissected cell populations

Because colorectal epithelia are prone to malignant transformation, it is important to understand their normal regulation and then to identify differences between the normal cells and the transformed cells. We investigated the gene expression pattern along colonic crypts using a novel gene expression analysis strategy. We combined laser-mediated microdissection of distinct areas within colonic crypts and used modified RNA arbitrarily primed PCR to generate probes for cDNA array hybridization. In the basal part of the crypt, proliferation-related and cell cycle-related genes such as the multifunctional transcription factor e2f-1 or the mismatch-related gene p58/HHR23B were predominantly expressed. In the lumenal part of the crypt, up-regulations of the cysteine protease mch4 and the proto-oncogene c-jun were found. Our findings indicate that e2f1, p58/HHR23B, and mch4 may be involved in key mechanisms leading to malignant transformation in the colonic crypt. Our results also suggest that the technique elucidated here allows identification of gene expression patterns in distinct areas of intestinal tissue samples.

Carcinogenic potential of duodenal reflux juice from patients with long-standing postgastrectomy

AIM: To determine whether study on the carcinogenic potential of reflux juice from patients with remote gastrectomy could clarify the inherent relationship between duodenal reflux and gastric stump cancer.

METHODS: A total of 37 reflux juice samples (13 Billroth I, 24 Billroth II) were employed in the present study. A two-stage transformation assay using BALB/c 3T3 cells was carried out to test the initiating or promoting activity of these samples.

RESULTS: Two of 18 (11.1%) reflux samples exerted initiating activities, whereas 9/19 (47.4%) samples enhanced the MNNG-initiating cell transformation, suggesting the duodenal reflux juice might more frequently possess the tumor-promoter activity (P = 0.029). In addition, there was no difference in initiating activities of the samples irrespective of surgical procedures (P = 0.488), while Billroth II samples exhibited stronger tumor-promoter activity than Billroth I samples (P = 0.027). Furthermore, the promoter activities were well correlated with the histological changes of the stomas (r_s = 0.625, P = 0.004), but neither their cytotoxicities nor initiating activities had this correlation (Probabilities were 0.523 and 0.085, respectively).

CONCLUSION: The duodenal reflux juice from patients with remote postgastrectomy did have carcinogenic potential, and suggested that tumor-promoting activity should principally account for the high incidence of gastric cancer in gastrectomy patients. In contrast, it is difficult to explain the high stump-cancer incidence with the "N-nitroso compounds" theory-a popular theory for the intact stomach carcinogenesis, and it seemed to be justified to focus chemoprevention of this cancer on the tumor-promoting potential of reflux juice.

Identification of differentially expressed genes in normal and tumor human gastric tissue

The search for differentially expressed genes in gastric cancer may help define molecular alterations and molecular diagnosis of gastric cancer. Using the differential display PCR technique, we identified 18 genes that are differentially expressed between normal and tumor human gastric tissues. Their expressions were verified with reverse Northern blot analysis and Northern blot analysis. Oxidative phosphorylation-related genes, antizyme inhibitor of ornithine decarboxylase, protein phosphatase-1beta, 35-kDa peroxisomal membrane protein, and cystic fibrosis transmembrane conductance receptor were highly expressed in tumor tissue, whereas pepsinogen A, Na-K ATPase alpha subunit, nerve growth factor receptor, and alpha-tropomyosin were highly expressed in normal tissue. In addition, 3 unknown genes were found to be differentially expressed in paired gastric tissues. These differentially expressed genes may provide significant opportunities for further understanding of gastric carcinogenesis and the molecular diagnosis of gastric cancer.

Efp as a primary estrogen-responsive gene in human breast cancer

We have previously isolated the efp (estrogen-responsive finger protein) that is required for the normal estrogen-induced cell proliferation. Here, we show the genomic organization of the human efp gene which consists of nine exons. The efp mRNA was expressed in human breast tumors and the estrogen-induced expression of the efp was found in MCF-7 human breast cancer cells. Moreover, efp promoter activity was enhanced through the estrogen-responsive element dependent on estrogen and estrogen receptor. These results suggest that the efp can mediate estrogen actions such as cell growth in human breast cancer as a primary responsive gene.

Estrogen receptor beta mRNA in colon cancer cells: growth effects of estrogen and genistein

Knowledge regarding the expression of the recently cloned estrogen receptor beta (ERbeta) in colonic mucosa is limited. In this study, we demonstrated that five human colon cancer cell lines, HT29, Colo320, Lovo, SW480, and HCT116, expressed ERbeta mRNA, but lacked ERalpha mRNA. Results from a cell growth assay demonstrated that these colon cancer cells were not influenced by estrogen, while genistein possessed slight growth inhibitory effects on HT29, Colo320 and Lovo cells at 10 microM, at which concentration is stimulated the growth of ERalpha-positive human breast cancer MCF-7 cells. Tamoxifen inhibited the growth of HT29 and Colo320 cells, dose-dependently, as well as MCF-7 cells. A transfected reporter plasmid containing a vitellogenin estrogen response element could be activated by estradiol in Colo320 cells. Taken together with previous reports, these data suggest that ERalpha and ERbeta may have different biological functions in colon cells.

[Analysis of gene expression patterns in rheumatoid synovial fibroblasts using RAP-PCR for differential display]

OBJECTIVE

Destruction of articular cartilage and bone by invading synovial fibroblasts is a typical histopathologic feature in rheumatoid arthritis (RA). However, little is known about specific up- or downregulation of genes leading to this aggressive phenotype. Thus, our aim was to identify genes, which are differentially expressed in RA synovial fibroblasts as compared to synovial fibroblasts derived from patients with osteoarthritis (OA) using RAP-PCR for differential display.

METHODS

After extraction of total RNA, the first step of RAP-PCR was performed using various different arbitrary 10-12-base primers for first-strand cDNA synthesis. Second-strand synthesis was achieved by cycling at low stringency conditions for 35 cycles using different arbitrary 10-base primers, followed by electrophoretic separation and sequence analysis of the amplified fingerprint products.

RESULTS

On average, approximately 70 different RNAs were obtained per primer, of which most were expressed both by RA and OA synovial fibroblasts. Using 26 different primer combinations, in total 12 cDNAs were differentially expressed between RA and OA synovial fibroblasts. In the RA group strong amplification of distinct PCR products suitable for sequencing could be observed. Sequence analysis identified these PCR products as highly homologous to various genes involved in regulation of cell cycle and metabolism.

CONCLUSION

The data indicate that RAP-PCR is a suitable method to identify differentially expressed genes in rheumatoid synovial fibroblasts potentially involved in the specific pathophysiology of RA.