Stool test for colorectal cancer screening--it's time to move!

Fecal occult blood testing (FOBT) is the most widely prescribed screening test for colorectal cancer (CRC) because it is simple, non-invasive, and it has been demonstrated that it reduces the mortality due to colorectal carcinomas (CRC). However, guaiac based fecal blood tests (gFOBT) suffer from poor sensitivity, particularly with respect to detecting early stages, as well as low acceptance among the population. Preliminary data on the detection of fecal proteins like calprotectin and tumour-M2-PK indicated that they might have better performance characteristics than the gFOBTs. However, these tests also suffer from low sensitivity and poor specificity especially for detecting early lesions. Recently developed immunological tests (iFOBT) demonstrate a significantly higher sensitivity and specificity. iFOBTs use antibodies specific to human hemoglobulin and therefore are not affected by the necessity of dietary and drug restrictions that otherwise limit the use of gFOBTs. At present iFOBTs seem to be the most cost-effective approach for non-invasive CRC screening. The analysis of fecal DNA represents an emerging new field for early detection of colorectal neoplasia. Small trials of multitarget assays demonstrated a sensitivity for CRC of 62 to 91% and a sensitivity for adenomas of 26 to 73%. The specificity of these assays is high ranging from 93 to 100%. The major drawback of fecal DNA testing, compared with other fecal colorectal cancer screening tests, is the unacceptable high cost.

Activators of peroxisome proliferator-activated receptors protect human skin from ultraviolet-B-light-induced inflammation.

Peroxisome proliferator-activated receptors (PPAR) are members of a nuclear receptor superfamily, which were initially described in the context of fatty acid degradation and adipocyte differentiation. In this study we tested the hypothesis that peroxisome proliferator-activated receptor activation also controls inflammation. In an in vitro model with human keratinocytes inflammation was mimicked by irradiation with ultraviolet B light (150 mJ per cm(2)). Activators for PPAR-alpha (WY-14,643, clofibrate) were shown to reverse ultraviolet-B-light-mediated expression of inflammatory cytokines (interleukin-6, interleukin-8). An activator preferentially for PPAR-beta (bezafibrate) did not show prominent effects on interleukin-6 and interleukin-8 expression. The anti-inflammatory action of WY-14,643 on skin cells was further demonstrated by in vivo testings in which topically applied WY-14,643 markedly increased the minimal erythema dose in ultraviolet-B-irradiated skin. Additionally, it was shown that ultraviolet B irradiation led to a decrease of all three peroxisome proliferator-activated receptor subsets at the mRNA level. Also transactivation of peroxisome proliferator response element was attenuated by ultraviolet B irradiation. The downregulation of peroxisome proliferator-activated receptors by ultraviolet B irradiation provides a possible mechanism that leads to exaggerated and prolonged inflammation. This work suggests the possibility of PPAR-alpha activators as novel nonsteroidal anti-inflammatory drugs in the topical treatment of common inflammatory skin diseases such as atopic dermatitis, psoriasis, and photodermatitis.

Reactive oxygen intermediates are involved in IL-8 production induced by hyperosmotic stress in human bronchial epithelial cells.

Changes in the osmolarity of the airway surface fluid have been described to be involved in the pathogenesis of exercise induced asthma, and are suggested as the major cause of the lung disease in cystic fibrosis. In this study, we examined the signaling pathway of hyperosmotic challenge to interleukin-8 (IL-8). Hyperosmolarity (NaCl) caused a time- and concentration-dependent increase in IL-8 expression and secretion in bronchial epithelial cells. These effects could be blocked by antioxidants, such as DMSO, DMTU, DTT, and beta-mercaptoethanol, suggesting an involvement of reactive oxygen intermediates (ROI) in the signal transduction of hyperosmolarity-induced IL-8 synthesis. Since IL-8 is regulated by MAP kinases, we examined the influence of MAP kinase inhibitors on hyperosmolarity-induced IL-8 expression. The results show that this induction is regulated by p38 MAPK and not by ERK1/2. Furthermore, antioxidants blocked the activation of p38 MAPK induced by hyperosmolarity. These results suggest that ROIs are critical for p38 MAPK mediated IL-8 expression by hyperosmolarity.

PPAR-gamma is selectively upregulated in Caco-2 cells by butyrate.

The peroxisome proliferator-activated receptor (PPAR)-gamma is a nuclear lipid-activable receptor controlling the expression of genes involved in lipid metabolism and adipocyte differentiation. In order to investigate the possible role of PPAR-gamma in the differentiation of intestinal epithelial cells, we examined its expression in the human colon carcinoma cell line Caco-2, which undergoes rapid cell differentiation in the presence of butyrate. PPARs were quantified on mRNA level by RT competitive multiplex PCR, the corresponding proteins were determined by Western blot. In contrast to PPAR-alpha and PPAR-beta, PPAR-gamma mRNA and protein increased significantly in butyrate-treated Caco-2 cells in a dose- and time-dependent manner. This effect was butyrate-specific, since no change in PPAR-gamma expression could be observed after incubation with propionate or valerate. Activation of PPAR-gamma by ciglitazone further increased butyrate-induced cell differentiation dose-dependently. These data demonstrate a role for PPAR-gamma in the regulation of cell differentiation in Caco-2 cells.

Expression of 5-lipoxygenase by human colorectal carcinoma Caco-2 cells during butyrate-induced cell differentiation.

Butyrate, a short-chain fatty acid, modulates proliferation and differentiation of normal and neoplastic colonocytes. We examined the expression of 5-lipoxygenase (5-LO) and its metabolites in human colorectal carcinoma (Caco-2) cells, exposed to differentiation-inducing doses of butyrate. Treatment with butyrate significantly increased 5-lipoxygenase mRNA and protein in comparison to nontreated cells. Cyclooxygenases (COX)-1 and COX-2 mRNA were not significantly influenced by the treatment. However, 5-LO activity, low in nontreated cells, increased only minimally after butyrate, and its metabolic product (5-HETE) was detectable neither in control nor in treated cells. In contrast, 15-HETE (a product of 15-LO, which is also upregulated by butyrate) rose significantly. We conclude that, although being overexpressed by butyrate on mRNA and protein level, 5-LO remains inactive in differentiating Caco-2 cells. This is likely to be due either to some associated actions of butyrate, or to 5-LO-inhibition by 15-HETE, concomitantly induced by butyrate treatment.

Reverse transcription-competitive multiplex PCR improves quantification of mRNA in clinical samples--application to the low abundance CFTR mRNA.

BACKGROUND: To monitor gene therapy, we wished to quantify cystic fibrosis transmembrane conductance regulator (CFTR) mRNA. We developed a PCR-based method to measure CFTR mRNA in clinical samples. METHODS: Expression was determined by reverse transcription-competitive multiplex PCR (RCMP) for CFTR and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) transcripts, and for serial dilutions of two internal cDNA standards consisting of CFTR and GAPDH mutants containing short deletions. The RCMP used simultaneous amplification of the gene of interest with a reporter gene in one reaction tube. The expression of CFTR was calculated with reference to the amount of GAPDH to correct for variations in initial RNA loading. RESULTS: Amplification of cDNAs derived from different amounts of RNA (1-4 microgram) gave similar GAPDH/CFTR ratios, with a coefficient of variation (CV) below 7.5%. RCMP was applied on nasal and bronchial brushings and shows a high variability of CFTR expression in non-cystic fibrosis donors. CONCLUSION: This method is precise and reproducible and advantageous for use with limited amounts of tissue, such as from biopsies or from nasal or bronchial brushings.

Transcriptional activation of plant defence genes by short-term air pollutant stress.

The expression of defence genes was monitored by RNA blot analyses in tobacco plants (Nicotiana tabacum cv. SR-1) treated with various air pollutants at realistic concentrations that prevail in urban areas. Six-week-old plants responded with an increase in the steady-state mRNA levels of phenylalanine ammonia-lyase (PAL), chalcone synthase (CHS), chitinase and beta-1,3-glucanase, when exposed to defined and subnecrotic concentrations of automobile exhaust and/or ozone over a period of 48 h. An enhanced expression of genes encoding mitochondrial and cytosolic superoxide dismutases suggested that air pollutants induced considerable oxidative stress. Moreover, wounding or elicitor treatment of plants already exposed to automobile exhaust and/or ozone additionally increased the expression of the above defence genes, but not so in NO(2). Since the main difference between NO(2) and exhaust gas is the absence of the hydrocarbon compounds in the former, we regard hydrocarbons as favourite candidates for the toxic effect of exhaust gas, and they possibly act by generating an enhanced oxidative stress.