Dysplastic Aberrant Crypt Foci: Biomarkers of Early Colorectal Neoplasia and Response to Preventive Intervention.

The discovery of aberrant crypt foci (ACF) more than three decades ago not only enhanced our understanding of how colorectal tumors form, but provided new opportunities to detect lesions prior to adenoma development and intervene in the colorectal carcinogenesis process even earlier. Because not all ACF progress to neoplasia, it is important to stratify these lesions based on the presence of dysplasia and establish early detection methods and interventions that specifically target dysplastic ACF (microadenomas). Significant progress has been made in characterizing the morphology and genetics of dysplastic ACF in both preclinical models and humans. Image-based methods have been established and new techniques that utilize bioactivatable probes and capture histologic abnormalities in vivo are emerging for lesion detection. Successful identification of agents that target dysplastic ACF holds great promise for intervening even earlier in the carcinogenesis process to maximize tumor inhibition. Future preclinical and clinical prevention studies should give significant attention to assessing the utility of dysplastic ACF as the earliest identifiable biomarker of colorectal neoplasia and response to therapy.See all articles in this Special Collection Honoring Paul F. Engstrom, MD, Champion of Cancer Prevention.

The modulatory effects of exercise on the inflammatory and apoptotic markers in rats with 1,2-dimethylhydrazine-induced colorectal cancer.

This study aimed to investigate the underlying mechanisms in anti-tumorigenesis effects of exercise through evaluation of inflammation and apoptosis. Twenty-four Wistar rats were divided into control, exercise, 1,2-dimethylhydrazine (DMH), and DMH + exercise. After a week, rats in the DMH group were given DMH twice a week for 2 weeks. Animals in the exercise groups performed exercise on a treadmill 5 days/week for 8 weeks. After 8 weeks of training, levels of COX-2, PCNA, Bax, Bcl-2, and procaspase-3/cleaved caspase-3 were assessed. Histological changes, number of aberrant crypt foci (ACF), and serum levels of TNF-α and IL-6 were also analyzed. ACF number was significantly decreased following the exercise program. Protein levels of COX-2 and PCNA and serum levels of IL-6 and TNF-α were significantly elevated in the rats receiving DMH and downregulated after performing the exercise program (P < 0.05). Exercise upregulated apoptosis, which was evident from the increased Bax/Bcl2 ratio, and enhanced the expression levels of activated caspase-3 as compared to the DMH group. The colonic architecture was improved in DMH + exercise. Exercise can effectively attenuate DMH-induced increase of inflammatory markers. Exercise induces apoptosis at the downstream of the inflammatory response. Therefore, exercise may play a role as a moderator of inflammation to exert protective effects against colon cancer.

Hyperbaric oxygen therapy reduces COX-2 expression in a dimethylhydrazine-induced rat model of colorectal carcinogenesis.

BACKGROUND: A better understanding of oncogenesis mechanisms should result in more effective approaches to colorectal cancer (CRC) treatment and prevention. Hyperbaric oxygen (HBO2) therapy is indicated as adjuvant treatment for infectious diseases as well as hypoxic and inflammatory lesions. The anti-inflammatory effect of HBO2 could reduce colorectal carcinogenesis. METHODS: 48 Wistar rats were randomly divided into the following groups: * G1 - control; * G2 - HBO2 treatment; * G3 - 1,2-dimethylhydrazine (DMH) injection only; * G4 - DMH injection and HBO2 treatment. These groups were further randomly divided into two subgroups: a. euthanasia at six weeks; and. b. euthanasia at 12 weeks. Animals belonging to G2 and G4 were subjected to 15 HBO2 sessions, performed every 24 hours at 2.0 atm absolute pressure, 90 minutes each. Cancer was induced via intraperitoneal injection of DMH in G3 and G4. The aberrant crypt foci index (ACFi), the cell nuclear antigen index (PCNA) and the cyclooxygenase-2 index (iCOX-2) were determined. RESULTS: After DMH administration, ACFi increased and was higher in subgroups euthanized at six weeks than in those sacrificed at 12 weeks (p < 0.001). HBO2 alone (G2) did not affect ACFi (p > or = 0.05). Larger increases of PCNA were detected in G2 versus G3 (p < 0.05). Comparison between G4 and control group mice revealed no differences in PCNA (p > 0.05). COX-2 was overexpressed in G3 (p < 0.0001) compared to G4. CONCLUSION: COX-2 expression was "induced" by DMH and reverted to a "wild"-type level of expression upon exposure to HBO2.