ABSTRACT
Macropinocytosis, an evolutionarily conserved, actin-dependent form of endocytosis, is involved in various physiological processes, including nutrient absorption, antigen presentation, and cell signaling transduction and migration. Oncogene activation and tumor suppressor inactivation induce macropinocytosis in tumors in the digestive system, involved in tumorigenesis and progression, whereas the inhibition of macropinocytosis slows the aggressive phenotype of digestive system tumors and improves the efficacy of anti-tumor drugs. Macropinocytosis can also be used as a delivery route for anti-tumor drugs. Therefore, macropinocytosis has been widely studied to develop new methods for the treatment of digestive system tumors.This paper reviews the role of macropinocytosis in the body, the regulation of macropinocytosis-related signaling pathway, as well as the mechanism of macropinocytosis in colorectal cancer, pancreatic ductal adenocarcinoma, liver cancer and other digestive system tumors, to provide reference for related researches.
ABSTRACT
To observe the effect of vasoactive intestinal peptide (VIP) on the metabolism of intestinal fluid and cyclic AMP protein kinase A signaling pathway (cAMP-PKA) and water channel protein 3 (AQP3) in rats with constipation, and to explore the mechanism of VIP in the treatment of constipation. Methods: A total of 45 healthy adult rats were randomly divided into a control group, a model group, a model +VIP group. After 4 weeks of VIP treatment, the first black stool time were examined with the ink gastric method; the water content in feces was calculated; the morphological changes in colonic tissues were observed by HE staining. The expression of VIP and AQP3 protein levels in colon tissues were detected by Western blot; and the cAMP, PKA, AQP3 mRNA expression levels were detected by quantitative real time polymerase chain reaction (qPCR). Results: Compared with the control group, the first black stool time was prolonged, the water content of fecal decreased significantly (both P<0.01); part of the colon mucosa epithelial cells were destructed; the goblet cell volume decreased and quantity was reduced; the contents of AQP3 and VIP in colon tissues were significantly decreased, and the cAMP, PKA and AQP3 mRNA levels were decreased in the model group (all P<0.05). Compared with the model group, the first black stool time in the model +VIP group was shortened, the fecal water content increased significantly (both P<0.05); the mucosal epithelium integrity improved, the number of goblet cells increased; the content of AQP3 and VIP in colon tissues was increased, and the cAMP, PKA, and AQP3 mRNA levels were elevated (all P<0.05). Conclusion: Intravenous injection of VIP can regulate intestinal fluid metabolism and improve the symptoms of constipation in rats, which might be related to the regulation of VIP-cAMP-PKA-AQP3 signaling pathway.