[TIPE2 inhibits the stemness of lung cancer cells by regulating the phenotypic polarization of tumor-associated macrophages].

Objective To investigate the regulatory effect of tumor necrosis factor-α-induced protein-8-like factor 2 (TIPE2) on the phenotype of lung cancer tumor-associated macrophages (TAM) and its influence on the stemness of lung cancer cells. Methods Mouse macrophage cell line RAW264.7 was cultured and infected with either LV-TIPE2 lentivirus or negative control LV-NC lentivirus. The TIPE2 expression in infected cells was assessed by real-time quantitative PCR (RT-qPCR) and Western blotting to verify transfection efficiency. The infected RAW264.7 cells were co-cultured with lung cancer cell line A549, and were divided into four groups: control group (RAW264.7 cells or A549 cells cultured alone), TAM group (RAW264.7 cells co-cultured with A549 cells), LV-NC group (RAW264.7 cells infected with LV-NC and co-cultured with A549 cells), LV-TIPE2 group (RAW264.7 cells infected with LV- TIPE2 and co-cultured with A549 cells). The RAW264.7 cells were collected after co-culture, and the expression of mannose receptor (CD206) protein of M2 macrophages was detected by cellular immunofluorescence staining. The proportions of M1 and M2 macrophages were detected by flow cytometry. After co-culture, A549 cells were collected, and their activity was assessed by CCK-8 assay. Self-renewal ability was evaluated using tumor cell pelleting experiment. The expression of stemness marker proteins-including cluster of differentiation 133 (CD133), transmembrane adhesion molecule (CD44), sex-determining region Y-box protein 2 (SOX2) and octamer-binding transcription factor 4 (OCT4)-was detected by Western blot. Results Compared with the control group or LV-NC group, the relative mRNA and protein expression levels of TIPE2 in RAW264.7 cells from the LV-TIPE2 group were significantly upregulated. Compared with the control group, the fluorescence intensity of M2-type macrophage marker CD206 protein in RAW264.7 cells from the TAM group was significantly increased, the proportion of M1-type macrophages was significantly decreased, and the proportion of M2-type macrophages was significantly increased. In contrast, compared with the TAM group, the fluorescence intensity of CD206 protein in RAW264.7 cells from the LV-TIPE2 group was significantly decreased, the proportion of M1-type macrophages was significantly increased, and the proportion of M2-type macrophages was significantly decreased. Compared with the control group, the proliferation activity of A549 cells in TAM group was significantly increased, the number of tumor pellet formation was significantly increased, and the relative expression levels of CD133, CD44, SOX2 and OCT4 were significantly up-regulated. However, compared with the TAM group, the proliferation activity of A549 cells from the LV-TIPE2 group was significantly decreased, the number of tumor pellet formation was significantly decreased, and the relative expression levels of CD133, CD44, SOX2 and OCT4 were significantly decreased. Conclusion TIPE2 can suppress the stemness of lung cancer cells by inhibiting the polarization of macrophages to M2-type, thereby exerting an anticancer effect.