[Shenbai Jiedu Fang inhibits AOM/DSS-induced colorectal adenoma formation and carcinogenesis in mice via miRNA-22-mediated regulation of the PTEN/PI3K/AKT signaling pathway]

OBJECTIVE

To observe the inhibitory effect of Shenbai Jiedu Fang (SBJDF, a compound recipe of traditional Chinese herbal drugs) on chemically induced carcinogenesis of colorectal adenoma in mice and explore the role of PTEN/PI3K/AKT signaling pathway in mediating this effect.

METHODS

Four-week-old male C57BL/6 mice were randomly divided into control group (n=10), AOM/DSS model group (n=20), low-dose (14 g/kg) SBJDF group (n=10) and high-dose (42 g/kg) SBJDF group (n= 10). In the latter 3 groups, the mice were treated with azoxymethane (AOM) and dextran sodium sulphate (DSS) to induce carcinogenesis of colorectal adenoma. In the two SBJDF treatment groups, SBJDF was administered daily by gavage during the modeling. The survival rate, body weight, general condition of the mice, and intestinal adenoma formation and carcinogenesis were observed. The expressions of proteins associated with the PTEN/PI3K/AKT signaling pathway in the intestinal tissue were detected using immunohistochemistry.

RESULTS

Compared with those in the model group, the mice treated with SBJDF, especially at the high dose, showed a significantly lower incidence of intestinal carcinogenesis and had fewer intestinal tumors with smaller tumor volume. Pathological examination showed the occurrence of adenocarcinoma in the model group, while only low-grade and high-grade neoplasia were found in low-dose SBJDF group; the mice treated with high-dose SBJDF showed mainly normal mucosal tissues in the intestines with only a few lesions of low-grade neoplasia of adenoma. Compared with those in the control group, the mice in the model group had significantly elevated plasma miRNA-222 level (P < 0.05), which was obviously lowered in the two SBJDF groups (P < 0.01). The results of immunohistochemistry revealed that compared with the model group, the two SBJDF groups, especially the high-dose group, had significantly up-regulated expressions of PTEN, P-PTEN and GSK-3β and down-regulated expressions of p-GSK-3 β, PI3K, AKT, P-AKT, β-catenin, c-myc, cyclinD1 and survivin in the intestinal tissues.

CONCLUSION

SBJDF can significantly inhibit colorectal adenoma formation and carcino-genesis in mice possibly through regulating miRNA-222 and affecting PTEN/PI3K/AKT signaling pathway.