Protection Of Exogenous Prostaglandin E2 On Chemotherapy—Induced Intestinal Mucosal Damage

Objective:To explore the protective effect and mechanism of exogenous prostaglandin E2(dmPGE2)on chemotherapy-induced intestinal damage.Methods:Forty five-week male C57BL/6 mice were randomly divided into 4 groups:control group,dmPGE2 group,5FU group and 5FU+dmPGE2 group.HE staining was used to observe the changes of mucosal morphology and count the number of absorptive cells in each group.IHC staining was used to count the number of Olfm4~+cells,Lysozyme~+cells and Cyclin D2~+cells in each group.PAS staining and silver staining were used to count the number of goblet cells and endocrine cells in each group,respectively.TUNEL staining was used to examine apoptotic cells in each group.Immunofluorescent staining was used to evaluate the expression of EP2 and BrdU in each group.The expression of Cyclin D1?Cyclin D2?FoxM1?FoxO1?FoxO3 and FoxO4 in each group were measured by qRT-PCR.Results:1.Histomorphological analysis:5FU treatment induced intestinal mucosal hyperemia,villus shedding,decreased villus height and crypt depth significantly when compared to the control group(P<0.05 or P<0.01).In comparistion to the 5FU group,the mucosal morphology in dmPGE2 treated mice was recovered.Villus height and crypt depth was significantly increased(P<0.01).2.Numbers of intestinal stem cells(ISCs):5FU treatment significantly decreased the number of Olfm4~+ISCs in each crypt when compared to the control animals(P<0.01).In comparison to 5FU-treated mice,dmPGE2 treatment significantly increased the numbers of Olfm4~+ISCs in each crypt(P<0.01).3.Proliferative and apoptotic assays:5FU treatment significantly decreased numbers of BrdU~+Olfm4~+ISCs and increased numbers of TUNEL~+cells in each crypt when compared to the control mice(P<0.01).In comparison to 5FU-treated animals,dmPGE2 treatment remarkably increased numbers of BrdU~+cells and BrdU~+Olfm4~+ISCs,decreased numbers of TUNEL~+cells in each crypt(P<0.01).4.Differentiation of ISCs:5FU treatment significantly decreased numbers of absorptive cells and goblet cells in each villus when compared to the control group(P<0.01).In comparison to 5FU-treated mice,dmPGE2 treatment significantly increased the number of goblet cells in each villus(P<0.05).5.Numbers of EP2~+cells:5FU treatment significantly increased numbers of EP2~+cells in each crypt when compared to the control group(P<0.01).6.Cell cycle related-gene expression:dmPGE2 treatment significantly increased expression of Cyclin D1?Cyclin D2 and FoxM1 when compared to the 5FU group(P<0.05 or P<0.01).7.Numbers of Cyclin D2~+cells:dmPGE2 treatment significantly increased numbers of Cyclin D2~+cells in each crypt when compared to the 5FU group(P<0.05).Conclusion:1.5-FU treatment leads to intestinal mucosal hyperemia,villus shedding and shortening,which subsequently induced intestinal mucosal injury.5FU inhibits the proliferation of ISCs,increases cryptic cell apoptosis,resulting in imbalance of differentiated epithelial cells.2.dmPGE2 could alleviate intestinal mucosal damage induced by 5FU treatment.The possible mechanism is that dmPGE2 binds to EP2 receptor in intestinal epithelial cells,promoting proliferation and differentiation of ISCs.dmPGE2 treatment also decreases cryptic cell apoptosis under 5FU stress.3.The underlying mechanism of dmPGE2-promoting ISCs proliferation might be mediated by the upregulation of Cyclin D2,which is induced by transcription factor FoxM1.