A mucinous histochemical study on malignancy of aberrant crypt foci (ACF) in rat colon

Lactobacillus acidophilus-Fermented Germinated Brown Rice Suppresses Preneoplastic Lesions of the Colon in Rats

Colorectal cancer (CRC) is a cancer associated with chronic inflammation. Whole grains and probiotics play a protective role against CRC. Fermented grains are receiving increased attention due to their anti-inflammatory and anti-cancer activities. Our previous study found that a combination of germinated brown rice (GBR) with probiotics suppressed colorectal carcinogenesis in rats. However, the cancer-preventive effect of probiotic-fermented GBR has not been reported. This study investigated the preventive effect and possible mechanism of GBR fermented by Lactobacillus acidophilus (FGBR) on colorectal carcinogenesis in rats induced by 1,2-dimethylhydrazine (DMH) and dextran sulfate sodium (DSS). DMH/DSS treatment induced preneoplastic aberrant crypt foci (ACF), elevated serum levels of tumor necrosis factor (TNF)-α, interleukin (IL)-6 and IL-1β, as well as decreased pro-apoptotic Bax expression. GBR and FGBR reduced the primary ACF number and decreased TNF-α, IL-6 and IL-1β levels. GBR and FGBR at the 2.5% level increased pro-apoptotic cleaved caspase-3 and decreased anti-apoptotic B-cell lymphoma 2 (Bcl-2) expressions. FGBR at the 2.5% level further reduced the number of sialomucin-producing ACF (SIM-ACF) and increased Bax expression. These results suggest that FGBR may inhibit preneoplastic lesions of the colon via activating the apoptotic pathway. This fermented rice product may have the potential to be developed as a novel dietary supplement for CRC chemoprevention.

Djulis (Chenopodium Formosanum) Prevents Colon Carcinogenesis via Regulating Antioxidative and Apoptotic Pathways in Rats

Djulis is a cereal crop rich in polyphenols and dietary fiber that may have nutraceutical activity to prevent colon cancer. This study was designed to examine the preventive effect of djulis on colon carcinogenesis in rats treated with 1,2-dimethylhydrazine (DMH). Rats were fed different AIN-93G-based diets: groups N and DMH were fed AIN-93G diet and groups LD, MD, and HD were fed AIN-93G diet containing 5, 10, and 20% djulis, respectively. All rats except for group N were injected with DMH to induce colon carcinogenesis. After 10 weeks, rats were sacrificed and colon and liver tissues were collected for analysis. The results showed that djulis-treated rats had significantly lower numbers of colonic preneoplastic lesions, aberrant crypt foci (ACF), sialomucin-producing (SIM)-ACF, and mucin-depleted foci. Djulis treatment increased superoxide dismutase and catalase activities in colon and liver. Djulis also reduced p53, Bcl-2, and proliferating cell nuclear antigen expressions and increased Bax and caspase-9 expressions. Besides, phenolic compounds and flavonoids were found rich in djulis. These results demonstrate the chemopreventive effect of djulis on carcinogen-induced colon carcinogenesis via regulating antioxidative and apoptotic pathways in rats. Djulis may have the potential to be developed as a valuable cereal product for chemoprevention of colon cancer.

Adenoma of colorectal laterally spreading tumor nongranular type with biological phenotypic features similar to cancer

BACKGROUND AND AIM

Colorectal laterally spreading tumors (LSTs) are morphologically subdivided into granular (LST-G) and nongranular (LST-NG) categories. We aimed to elucidate the differences in oncogenic characteristics between the two types.

METHODS

Laterally spreading tumors resected by endoscopic submucosal dissection and surgery from March 2009 to May 2017 were examined for p53 positivity, Ki-67 labeling index (LI), microvessel density, degree of fibrosis, intensities of inducible nitric oxide synthase (iNOS) and nitrotyrosine (NT), and expression of acid mucins. We compared these factors between adenomas, noninvasive cancers, and invasive cancers, both LST-G and LST-NG.

RESULTS

Ninety-three LST-G (53 adenomas [LST-GA] and 40 cancers [LST-GC]) and 55 LST-NG (24 adenomas [LST-NGA] and 31 cancers [LST-NGC]) were evaluated. Although p53 positivity was lower in LST-GA than in LST-NGA (P < 0.001), there was no difference between LST-GC and LST-NGC. Ki-67 LI was higher in LST-NGA than in LST-GA (P < 0.001) and higher in LST-NGC than in LST-GC of noninvasive cancers (P < 0.001). Microvessel density and degree of fibrosis were higher in LST-NGA than in LST-GA (P < 0.001), and intensities of iNOS and NT were also higher in LST-NGA than in LST-GA (P < 0.001). Expression of acid mucins was lower in LST-NGA than in LST-GA (P < 0.001). Although there were significant differences in p53 positivity, Ki-67 LI, microvessel density, degree of fibrosis, intensities of iNOS and NT, and expression of acid mucins between LST-GA and LST-NGA, these factors were only slightly different between LST-GC and LST-NGC of invasive cancers.

CONCLUSIONS

Unlike LST-GA, LST-NGA possessed phenotypic features similar to cancer.

Wheat Type (Class) Influences Development and Regression of Colon Cancer Risk Markers in Rats

We previously found red wheat more effective than white wheat in reducing colon cancer risk in rats when fed during initiation and postinitiation stages. Here we examine the effect of wheat on colon cancer risk in early and late postinitiation stages in carcinogen-treated rats. Four groups were fed a basal diet, 1 group a red wheat diet, and 1 group a white wheat diet. After 6 wk, 1 basal, the red and white groups were killed (early postinitiation stage). Of the remaining basal groups, 1 continued on the basal diet, 1 was switched to red and another to white wheat for 8 more wk (late postinitiation stage). Red and white wheat significantly reduced morphological [aberrant crypt foci (ACF)] and biochemical (β-catenin accumulated crypts) markers in both early and late postinitiation stages. Both wheat diets reduced dysplasia markers (sialomucin-expressing ACF and mucin depleted foci), compared to the basal diet, during the late postinitiation stage, but red wheat more so. Only red wheat significantly reduced the number of metallothionein-positive crypts, a stem cell mutation marker, in both stages. Overall, red wheat flour reduced risk markers more than white wheat flour, and this was more pronounced in the late post-initiation stage.

Reduction in colon cancer risk by consumption of kava or kava fractions in carcinogen-treated rats

Epidemiological studies suggest that kava reduces colon cancer risk. However, no experimental studies of the chemopreventive properties of kava toward colon cancer have been reported. Further, there are concerns regarding hepatotoxicity of kava. The goal of this study was to determine whether kava consumption reduces markers of colon cancer in an animal model and to study the safety of kava. An ethanolic extract and polar and nonpolar fractions of the kava extract were fed to rats for 12 days prior to, during, and after administration of dimethylhydrazine, a colon-specific carcinogen. After 14 wk, rats fed the nonpolar extract had a significant reduction in precancerous lesions [aberrant crypt (AC) foci (ACF)] as well as large (≥ 4 AC/ACF) sialomucin-only expressing foci, an indicator of greater tumorigenic potential, compared to the control group. Groups fed the ethanolic extract and polar kava fraction trended toward reductions in ACF and large sialomucin-only expressing foci. The combined kava groups had significantly fewer total AC, ACF, large ACF, and large sialomucin-only expressing foci compared to the control group. Histological examination found no hepatic lesions in animals consuming the kava diets, suggesting that kava is safe to consume. Our results support that kava may reduce colon cancer risk.

Effects of adlay bran and its ethanolic extract and residue on preneoplastic lesions of the colon in rats

BACKGROUND

Adlay (Coix lachryma-jobi L. var. ma-yuen Stapf) is a cereal crop used in traditional Chinese medicine and as a nutritious food. Epidemiologists have suspected that the low cancer rates in southeastern China might be related to adlay. Previous studies have shown that adlay has anti-tumour and anti-inflammatory activity. This study investigated the effect of adlay bran and its fractions on chemically induced colon carcinogenesis in rats.

RESULTS

Adlay bran and its ethanolic extract and residue significantly reduced the number of preneoplastic aberrant crypt foci (ACF) and modified their mucin composition. The inhibitory effect of adlay bran ethanolic extract on ACF showed a dose dependence. Adlay bran and its ethanolic extract suppressed small ACF (one, two or three crypts) and ACF in the distal colon, while the residue suppressed large ACF (four or more crypts).

CONCLUSION

These findings suggest the possibility that adlay bran and its ethanolic extract and residue inhibit colonic preneoplastic lesions in an early stage. Adlay and its fractions may have the potential to be developed as chemopreventive cereal products.

Modulation of transforming growth factor beta2 (TGF-beta2) by inositol hexaphosphate in colon carcinogenesis in rats

PURPOSE

To evaluate modulation in the expression of Transforming growth factor beta2 (TGF-beta2) in short-term colon carcinogenesis.

METHODS

64 male rats was used, comprising 4 groups of 16 animals each: group 1 received Inositol hexaphosphate (IP6) and azoxymethane (AOM); group 2, AOM alone; group 3, IP6 alone; group 4 was used as control. Groups 1 and 3 were given 1% IP6 in drinking water for 6 weeks. AOM was administered subcutaneously at weeks 3 and 4 of the experiment at 20 mg/kg of body weight each week. Immunohistochemical processing was performed with the use of anti-TGF-beta2 primary antibodies in right colon samples and quantitation of TGF-beta2 as percentage of expression, through computer-assisted image processing.

RESULTS

mean values of TGF-beta2 expression were 9.0 +/- 3.9% for group 4 (control), 12.7 +/- 4.0% for group 3 (IP6), 19.3 +/- 6.2% for group 2 (AOM), and 13.1 +/- 5.3% for group 1 (IP6+AOM). The value of p was calculated as 0.0001 for a 5% or lower significance level.

CONCLUSION

the experiment revealed a significant increase in TGF-beta2 expression in right colon with the administration of AOM, and a significant decrease in TGF-beta2 expression when IP6 was administered with AOM.

Significance and role of early-lesions in experimental colorectal carcinogenesis

Preneoplastic or precancerous lesions in the large bowel have attracted much attention, and aberrant crypt foci (ACF) topographically identified in the colonic mucosa have found application as effective endpoint lesions for detection of chemopreventive agents as well as carcinogenic risk assessment of environmental agents. While many ACF are regarded as hyperplastic in nature, lacking the potential lesion to give rise to neoplasia, a subset termed dysplastic ACF, or newly identified "mucin depleted foci (MDF)", and "beta-catenin accumulated crypts (BCAC)" are suggested to be more reliably related to colorectal tumorigenesis in rodents. ACF and MDF can be visualized on the surface of colonic mucosa and BCAC were recently identified by our laboratory in rodents en face in cross sections. In particular, BCAC having a similar pattern of beta-catenin gene mutation to that observed in colonic carcinomas appear to be direct precursors. This review provides a review and discussion of the relevant literature relative to early lesions in colorectal carcinogenesis.