Shuyuwan Regulates M1/M2 Polarization of Tumor-associated Macrophages to Inhibit Progression of Colorectal Cancer / 中国实验方剂学杂志

ABSTRACT

ObjectiveTo explore the molecular mechanism of Shuyuwan regulating polarization of tumor-associated macrophages （TAMs） to inhibit the progression of colorectal cancer （CRC）. MethodThe nude mouse model of orthotopic transplantation of colon cancer was established. Male BALB/c-nu nude mice （n=28， 4 weeks old） were randomly assigned into 4 groups （n=7）： Model group （normal saline） and low-， medium-， and high-dose （1.725， 2.310， 2.895 g·kg-1·d-1， respectively） Shuyuwan groups. On day 9 after the tumor block was inoculated， the mice were administrated by gavage with corresponding agents at a dose of 15 mL·kg-1 once a day， 6 days a week， and no agent on the 7th day. After two consecutive weeks of intervention， the nude mice were sacrificed and the tumor samples were collected. A part of the colon tissue and the tumor tissue was used to prepare sections， and hematoxylin-eosin （HE） staining was performed for pathological observation. The expression of inducible nitric oxide synthase （iNOS） and arginase-1 （Arg-1） in the tumor tissue was detected by immunohistochemistry （IHC）. The mRNA levels of interleukin-12 （IL-12）， epidermal growth factor （EGF）， and transforming growth factor-β1 （TGF-β1） in the tumor tissue were determined by Real-time polymerase chain reaction （PCR）. Western blot was employed to determine the protein levels of iNOS， IL-12， EGF， and TGF-β1 in the tumor tissue. ResultCompared with the model group， Shuyuwan inhibited the growth of colon cancer cells in nude mice and caused the tumor cell necrosis in different degrees. The high-dose Shuyuwan group had the strongest inhibitory effect on the growth of tumor cells， which basically lost the normal morphology. Furthermore， Shuyuwan up-regulated the expression of iNOS and IL-12 in M1-type macrophages （P<0.05） and down-regulated the expression of Arg-1， EGF， and TGF-β1 in M2-type macrophages （P<0.05）， which indicated the weakened polarization of macrophages toward M2 type and the enhanced polarization toward M1 type after treatment with Shuyuwan. ConclusionShuyuwan can inhibit the growth of orthotopically transplanted colon tumor by blocking the polarization of TAMs to M2 type and promoting the polarization of TAMs to M1 type.