Snai1 regulates cell lineage allocation and stem cell maintenance in the mouse intestinal epithelium.

Snail family members regulate epithelial-to-mesenchymal transition (EMT) during invasion of intestinal tumours, but their role in normal intestinal homeostasis is unknown. Studies in breast and skin epithelia indicate that Snail proteins promote an undifferentiated state. Here, we demonstrate that conditional knockout of Snai1 in the intestinal epithelium results in apoptotic loss of crypt base columnar stem cells and bias towards differentiation of secretory lineages. In vitro organoid cultures derived from Snai1 conditional knockout mice also undergo apoptosis when Snai1 is deleted. Conversely, ectopic expression of Snai1 in the intestinal epithelium in vivo results in the expansion of the crypt base columnar cell pool and a decrease in secretory enteroendocrine and Paneth cells. Following conditional deletion of Snai1, the intestinal epithelium fails to produce a proliferative response following radiation-induced damage indicating a fundamental requirement for Snai1 in epithelial regeneration. These results demonstrate that Snai1 is required for regulation of lineage choice, maintenance of CBC stem cells and regeneration of the intestinal epithelium following damage.

Modeling Intestinal Carcinogenesis Using In Vitro Organoid Cultures.

Mouse models of intestinal carcinogenesis are very powerful tools for studying the impact of specific mutations on tumor initiation and progression. Mutations can be studied both singularly and in combination using conditional alleles that can be induced in a temporal manner. The steps in intestinal carcinogenesis are complex and can be challenging to image in live animals at a cellular level. The ability to culture intestinal epithelial tissue in three-dimensional organoids in vitro provides an accessible system that can be genetically manipulated and easily visualized to assess specific biological impacts in living tissue. Here, we describe methodology for conditional mutation of genes in organoids from genetically modified mice via induction of Cre recombinase induced by tamoxifen or by transient exposure to TAT-Cre protein and subsequent phenotyping of the organoids. This methodology provides a rapid platform for assessing the cellular changes induced by specific mutations in intestinal tissue.

Modelling Intestinal Carcinogenesis Using In Vitro Organoid Cultures.

Mouse models of intestinal carcinogenesis are very powerful for studying the impact of specific mutations on tumour initiation and progression. Mutations can be studied both singularly and in combination using conditional alleles that can be induced in a temporal manner. The steps in intestinal carcinogenesis are complex and can be challenging to image in live animals at a cellular level. The ability to culture intestinal epithelial tissue in three-dimensional organoids in vitro provides an accessible system that can be genetically manipulated and easily visualised to assess specific biological impacts in living tissue. Here, we describe methodology for conditional mutation of genes in organoids from genetically modified mice via induction of Cre recombinase induced by tamoxifen or by transient exposure to TAT-Cre protein. This methodology provides a rapid platform for assessing the cellular changes induced by specific mutations in intestinal tissue.

Antioxidant Supplementation: A Linchpin in Radiation-Induced Enteritis.

Radiation enteritis is one of the most feared complications of abdominal and pelvic regions. Thus, radiation to abdominal or pelvic malignancies unavoidably injures the intestine. Because of rapid cell turnover, the intestine is highly sensitive to radiation injury, which is the limiting factor in the permissible dosage of irradiation. Bowel injuries such as fistulas, strictures, and chronic malabsorption are potentially life-threatening complications and have an impact on patient quality of life. The incidence of radiation enteritis is increasing because of the current trend of combined chemotherapy and radiation. The consequences of radiation damage to the intestine may result in considerable morbidity and even mortality. The observed effects of ionizing radiation are mediated mainly by oxygen-free radicals that are generated by its action on water and are involved in several steps of signal transduction cascade, leading to apoptosis. The oxyradicals also induce DNA strand breaks and protein oxidation. An important line of defense against free radical damage is the presence of antioxidants. Therefore, administration of antioxidants may ameliorate the radiation-induced damage to the intestine.

Status of colorectal cancer devices: present scenario.

PURPOSE: The purpose of this study was the colonoscopic detection and removal of neoplasia from the colorectum to prevent the development of colorectal cancer. METHOD: Various online medical databases were searched such as PubMed, ACS, NCI, NIH, WHO, etc. for relevant publications and clinical trials for new developments in colonoscopic devices that are intended for diagnostic visualization and therapeutic interventions of the digestive tract. RESULT: HD colon and I-Scan both has shown to increase the detection of sporadic adenomas with high quality. Third Eye Retroscope confers the backward view of colon, but aeroscope screens the entire colon in 30-60 min. Narrow-band imaging enhances mucosal and vascular details through the color differentiation of precancerous or cancerous polyp, compared to white light colonoscopy. The PillCam Colon Capsule is another new technique which is easily inserted and painless. In case of chemotherapy, Therasphere with Yttrium-90 has good results in the treatment of colorectal adenocarcinoma metastasis. Radiofrequency ablation is a good technique for tumors ablation and Staple Line Reinforcement prevents the leak during and post-surgery of colon. FOBT is much more sensitive and cheaper test for colorectal cancer screening. CONCLUSION: Registered clinical trials have shown promising results for neoplasia detection by I-Scan, TER, and NBI imaging techniques will change current colonoscopic practice in colorectal cancer screening. However, more studies and inventions are required for improving the patient safety and efficacy.

Current status of pharmacological treatment of colorectal cancer.

AIM: To review the clinical trials for the development in drugs for chemotherapeutic treatment of colorectal cancer (CRC). METHODS: A systematic review identified randomized controlled trials (RCTs) assessing drugs for the treatment of CRC or adenomatous polyps from www.clinicaltrials.gov. Various online medical databases were searched for relevant publications. RESULTS: Combination treatment regimens of standard drugs with newer agents have been shown to improve overall survival, disease-free survival, time to progression and quality of life compared to that with standard drugs alone in patients with advanced colorectal cancer. The FOLFOXIRI regimen has been associated with a significantly higher response rate, progression-free survival and overall survival compared to the FOLFIRI regimen. CONCLUSION: Oxaliplatin plus intravenous bolus fluorouracil and leucovorin has been shown to be superior for disease-free survival when compared to intravenous bolus fluorouracil and leucovorin. In addition, oxaliplatin regimens were more likely to result in successful surgical resections. First line treatment with cetuximab plus fluorouracil, leucovorin and irinotecan has been found to reduce the risk of metastatic progression in patients with epidermal growth factor receptor-positive colorectal cancer with unresectable metastases. The addition of bevacizumab has been shown to significantly increase overall and progression-free survival when given in combination with standard therapy.

Anti-proliferative action of silibinin on human colon adenomatous cancer HT-29 cells.

BACKGROUND: Silibinin a flavonoid from milk thistle (Silybum marianum) exhibit a variety of pharmacological actions, including anti-proliferative and apoptotic activities against various types of cancers in intact animals and cancer cell lines. In the present study, the effect of silibinin on human colon cancer HT-29 cells was studied. METHOD: Incubations of cells with different silibinin concentrations (0.783-1,600 ug/ml) for 24, 48 or 72 h showed a progressive decline in cell viability. RESULTS: Loss of cell viability was time dependent and optimum inhibition of cell growth (78%) was observed at 72 h. Under inverted microscope, the dead cells were seen as cell aggregates. IC50 (silibinin concentration killing 50% cells) values were 180, 110 and 40 ug/ml at 24, 48 and 72 h respectively. CONCLUSION: These findings re-enforce the anticancer potential of silibinin, as reported earlier for various other cancer cell lines (Ramasamy and Agarwal (2008), Cancer Letters, 269: 352-62).

Antecedentes: Silibinina un flavonoide a partir de la leche de cardo mariano (Silybum marianum) exhiben una variedad de acciones farmacológicas, incluyendo actividades anti-proliferativos y apoptóticos contra varios tipos de cánceres en animales intactos y líneas celulares de cáncer. En el presente estudio, se estudió el efecto de silibinina en células humanas de cáncer de colon HT-29. Método: Las incubaciones de las células con diferentes concentraciones silibinin (0,783-1.600 ug/ml) para 24, 48 o 72 horas mostró un descenso progresivo de la viabilidad celular. Resultados: La pérdida de la viabilidad celular fue de tiempo de inhibición dependiente y óptima de crecimiento de las células (78%) se observó a las 72 horas. Bajo microscopio invertido, las células muertas fueron vistos como los agregados de células. IC50 (concentración de silibinina matar a las células 50%) los valores fueron 180, 110 y 40 ug/ml a las 24, 48 y 72 horas, respectivamente. Conclusión: Estos resultados volver a hacer cumplir la potenciales contra el cáncer de silibinina, como se informó anteriormente para varias otras líneas celulares de cáncer (Ramasamy y Agarwal (2008), Cancer Letters, 269: 352-62).

Effect of antioxidant supplementation on digestive enzymes in radiation induced intestinal damage in rats.

PURPOSE: Intestinal mucosa, a rapidly proliferating tissue, is highly sensitive to radiation and undergoes apoptosis as a consequence of over generation of oxidative free radicals and the lack of the antioxidants. Thus the present study was designed to investigate the intestinal damage induced by radiation and to study if supplementation of the diet with antioxidant vitamins could ameliorate the intestinal damage and its digestive activity, as determined by the expression of various border enzymes. MATERIALS AND METHODS: Swiss Albino rats (150-200 g body weight) were divided into six groups. Group I: Control untreated; Group II: Irradiated; Group III: Irradiated + vitamin A; Group IV: Irradiated + vitamin C; Group V: Irradiated + vitamin E; and Group VI: Irradiated + lycopene. Animals were exposed to whole body γ-radiation from (60)Co at the rate of 8 Gy for 15 min/rat. Intestinal morphology and changes in various digestive enzymes together with, DNA damage was studied in six groups and each group consisted of 18 animals. RESULTS: The gastrointestinal toxicity resulted in malabsorption, diarrhoea, weight loss, loss of appetite, abdominal haemorrhage and hair loss. The activities of sucrase and alkaline phosphatase were elevated and those of lactase, leucine aminopeptidase (LAP) and gamma-glutamyl transpeptidase or tranferase (γ-GTP) were markedly reduced. Antioxidant vitamin A, C or E supplementations prevented changes in brush border enzyme activities as compared to lycopene administration in rat intestine by radiation exposure. Intestinal histology showed that the vitamin supplementation to irradiated rats minimized the intestinal damage in rats. CONCLUSION: These findings suggest that the epithelial lining of the intestine is highly sensitive to radiation exposure and supplementation of antioxidant vitamins is helpful in minimizing the intestinal damage and supplementation by vitamin E was most potent in ameliorating the intestinal aberrations.