[miR-373 inhibits M2 polarization of tumor associated macrophages and affects rectal cancer cells by regulating JAK2/STAT6 signal pathway].

Objective To explore the effects of miR-373 and Janus kinase 2/signal transducer and activator of transcription 6 (JAK2/STAT6) signaling pathways on the M2 polarization of tumor associated macrophages (TAM) in rectal cancer. Methods THP-1 cells were induced into M0/M1/M2 macrophages, M0 macrophages were cocultured with Caco-2 cells to obtain TAM, Flow cytometry was used to detect the expression of CD86 and CD206, Real-time quantitative qPCR and Western blot were used to detect miR-373, inducible nitric oxide synthase (iNOS), toll-like receptor 4 (TLR-4), interleukin 1β (IL-1β), tumor necrosis factor α (TNF-α), arginase 1 (Arg1), chitinase 3-like 1 (Ym1), resistin like α (Fizz1), IL-10 mRNA and protein levels. TAM were transfected and divided into overexpressing miR-373 group (miR-373-TAM) and control group (miR-NC-TAM), overexpressing miR-373+JAK2-TAM group (miR-373 combined with JAK2-TAM) and control group (miR-373 combined with NC-TAM), and then cocultured with Caco-2 cells. Flow cytometry was used to detect the expression of CD206 in TAM; Real-time quantitative PCR and Western blot were used to detect miR-373, Arg1, Ym1, Fizz1, IL-10, JAK2, STAT6 mRNA and protein levels in TAM; CCK-8 assay, colony formation assay, and Transwell assay were used to detect the proliferation, migration, and invasion ability of Caco-2 cells. Thirty nude mice were randomly divided into Caco-2 cells group, Caco-2 cells combined with miR-NC-TAM group, and Caco-2 cells combined with miR-373-TAM group, with 10 mice in each group. Rats in each group were subcutaneously injected with pure Caco-2 cells, Caco-2 cells combined with TAM, and Caco-2 cells combined with TAM overexpressing miR-373. After 4 weeks of cell inoculation, immunofluorescence staining was used to detect F4/80⁺CD206⁺cells level in tumor tissue; Real-time quantitative PCR and Western blot were used to detect miR-373, JAK2, STAT6, Arg1, Ym1, Fizz1, IL-10 mRNA and protein levels in tumor tissues. Results TAM tended to M2 polarization. After overexpression of miR-373, miR-373 level in TAM was increased, while Arg1, Ym1, Fizz1, IL-10, JAK2, STAT6 mRNA and protein levels were decreased, proliferation, migration, invasion ability of Caco-2 cells were decreased; Overexpression of JAK2 could partially reverse the effect of overexpression of miR-373 on the M2 polarization of TAM and proliferation, migration, invasion ability of Caco-2 cells. TAM could promote tumor growth; Overexpression of miR-373 could inhibit tumor growth and inhibit M2 polarization of TAM. Conclusion miR-373 could inhibit M2 polarization of TAM in rectal cancer, and miR-373 might inhibit proliferation and metastasis of rectal cancer cells by regulating the JAK2/STAT6 pathway.