AIM To evaluate the effect of orally administered plecanatide on colorectal dysplasia in Apc^(+/Min-FCCC)mice with dextran sodium sulfate(DSS)-induced inflammation.METHODS Inflammation driven colorectal carcinogenesis...AIM To evaluate the effect of orally administered plecanatide on colorectal dysplasia in Apc^(+/Min-FCCC)mice with dextran sodium sulfate(DSS)-induced inflammation.METHODS Inflammation driven colorectal carcinogenesis was induced in Apc^(+/Min-FCCC)mice by administering DSS in their drinking water.Mice were fed a diet supplemented with plecanatide(0-20 ppm)and its effect on the multiplicity of histopathologically confirmed polypoid,flat and indeterminate dysplasia was evaluated.Plecanatide-mediated activation of guanylate cyclase-C(GC-C)signaling was assessed in colon tissues by measuring cyclic guanosine monophosphate(cG MP)by ELISA,protein kinase G-II and vasodilator stimulated phosphoprotein by immunoblotting.Ki-67,c-myc and cyclin D1 were used as markers of proliferation.Cellular levels and localization of b-catenin in colon tissues were assessed by immunoblotting and immunohistochemistry,respectively.Uroguanylin(UG)and GC-C transcript levels were measured by quantitative reverse transcription polymerase chain reaction(RT-PCR).A mouse cytokine array panel was used to detect cytokines in the supernatant of colon explant cultures.RESULTS Oral treatment of Apc^(+/Min-FCCC)mice with plecanatide produced a statistically significant reduction in the formation of inflammation-driven polypoid,flat and indeterminate dysplasias.This anti-carcinogenic activity of plecanatide was accompanied by activation of cG MP/GC-C signaling mediated inhibition of Wnt/b-catenin signaling and reduced proliferation.Plecanatide also decreased secretion of pro-inflammatory cytokines(IL-6,IL-1 TNF),chemokines(MIP-1,IP-10)and growth factors(GCSF and GMCSF)from colon explants derived from mice with acute DSS-induced inflammation.The effect of plecanatidemediated inhibition of inflammation/dysplasia on endogenous expression of UG and GC-C transcripts was measured in intestinal tissues.Although GC-C expression was not altered appreciably,a statistically significant increase in the level of UG transcripts was detected in the proximal small intestine and colon,potentially due to a reduction in intestinal inflammation and/or neoplasia.Taken together,these results suggest that reductions in endogenous UG,accompanied by dysregulation in GC-C signaling,may be an early event in inflammation-promoted colorectal neoplasia;an event that can potentially be ameliorated by prophylactic intervention with plecanatide.CONCLUSION This study provides the first evidence that orally administered plecanatide reduces the multiplicity of inflammation-driven colonic dysplasia in mice,demonstrating the utility for developing GC-C agonists as chemopreventive agents.展开更多
基金Supported by National Cancer Institute(CA133689 to Kunwar Shailubhai,CA006927 to Fox Chase Cancer Center)an appropriation from the Commonwealth of Pennsylvania(Fox Chase Cancer Center)
文摘AIM To evaluate the effect of orally administered plecanatide on colorectal dysplasia in Apc^(+/Min-FCCC)mice with dextran sodium sulfate(DSS)-induced inflammation.METHODS Inflammation driven colorectal carcinogenesis was induced in Apc^(+/Min-FCCC)mice by administering DSS in their drinking water.Mice were fed a diet supplemented with plecanatide(0-20 ppm)and its effect on the multiplicity of histopathologically confirmed polypoid,flat and indeterminate dysplasia was evaluated.Plecanatide-mediated activation of guanylate cyclase-C(GC-C)signaling was assessed in colon tissues by measuring cyclic guanosine monophosphate(cG MP)by ELISA,protein kinase G-II and vasodilator stimulated phosphoprotein by immunoblotting.Ki-67,c-myc and cyclin D1 were used as markers of proliferation.Cellular levels and localization of b-catenin in colon tissues were assessed by immunoblotting and immunohistochemistry,respectively.Uroguanylin(UG)and GC-C transcript levels were measured by quantitative reverse transcription polymerase chain reaction(RT-PCR).A mouse cytokine array panel was used to detect cytokines in the supernatant of colon explant cultures.RESULTS Oral treatment of Apc^(+/Min-FCCC)mice with plecanatide produced a statistically significant reduction in the formation of inflammation-driven polypoid,flat and indeterminate dysplasias.This anti-carcinogenic activity of plecanatide was accompanied by activation of cG MP/GC-C signaling mediated inhibition of Wnt/b-catenin signaling and reduced proliferation.Plecanatide also decreased secretion of pro-inflammatory cytokines(IL-6,IL-1 TNF),chemokines(MIP-1,IP-10)and growth factors(GCSF and GMCSF)from colon explants derived from mice with acute DSS-induced inflammation.The effect of plecanatidemediated inhibition of inflammation/dysplasia on endogenous expression of UG and GC-C transcripts was measured in intestinal tissues.Although GC-C expression was not altered appreciably,a statistically significant increase in the level of UG transcripts was detected in the proximal small intestine and colon,potentially due to a reduction in intestinal inflammation and/or neoplasia.Taken together,these results suggest that reductions in endogenous UG,accompanied by dysregulation in GC-C signaling,may be an early event in inflammation-promoted colorectal neoplasia;an event that can potentially be ameliorated by prophylactic intervention with plecanatide.CONCLUSION This study provides the first evidence that orally administered plecanatide reduces the multiplicity of inflammation-driven colonic dysplasia in mice,demonstrating the utility for developing GC-C agonists as chemopreventive agents.
