Patients. The clinicopathological and survival data were obtained from patients with lung adenocarcinoma who had undergone surgery between January 2013 and December 2016. Tumors were classified according to the 8th edition of the AJCC TNM system for lung cancer. The inclusion criteria were as follows: (1) primary lung adenocarcinoma diagnosed by pathological diagnosis; (2) cases had received no previous treatment before operation. The age, gender, smoking history, tumor site, tumor size, lymphatic metastasis, TNM stage, and survival information were acquired from medical records. This retrospective study was approved by the ethics committee of our hospital, and the informed consent was exempted.
Animal experiments. The mouse adenocarcinoma cell line (LLC) was purchased from ATCC (Manassas, USA). LLC were cultured in DMEM supplemented with 10% FBS. All C57BL/6 mice were obtained from the vital river company. For tumor growth experiments, 2 × 106 LLC cells were suspended in 100 ul of DMEM and injected subcutaneously into the right back of 6 weeks old male mice. Mice were randomly divided into experimental or control (scramble) group matched for the tumor volumes on day 4 post tumor inoculation. The experimental group mice were injected intravenously with TMSB10 shRNA lentivirus (GENE, Shanghai) every week, and scramble cohorts were injected intravenously with scramble shRNA lentivirus. Tumor sizes were measured with calipers each 5 days throughout the in vivo experiment.
Isolation of tumor-infiltrating immune cells. The excised tumors were finely minced and suspended in HBSS (Thermo Fisher, 14025134) supplemented with 2%FBS (Gibco, 1921005PJ), 1% hyaluronidase (Sigma, 37326-33-3), Collagenase 4 at 1 mg/mL (Sigma, SCR103) and 0.25% DNase I (Roche, 11284932001) at 37℃ on a shaker at 80 rpm for 2 hours. The mixture was then mixed with 10% PBS (suspended in HBSS) in a 1:1 ratio and filtered through a 50um mesh. Percoll (Sigma, P1644) was used to purify tumor-infiltrating leukocytes (TILs) via density gradient centrifugation. Briefly, 60% Percoll was firstly added to the bottom of a glass tube and then 30% Percoll was carefully added by a Pasteur pipette. Finally, the filtered cells were gently resuspended in the 30% Percoll. The suspension was centrifuged at 400 g for 25 min at room temperature. After centrifugation, the pellet of erythrocytes and excess buffer/percoll were removed, leaving a purified population of leukocytes at the interface. The purified tumor-infiltrating leukocytes were washed twice with FACS buffer prior to flow cytometry analysis.
Flow cytometry. Cell staining was operated on ice and away from light. For surface staining, the purified cells from tumor tissues were incubated with mouse Fc block (1:200, BD Biosciences, BD553141) in 4℃ for 30 min before staining with relevant conjugated antibodies. The relevant fluorescent-labeled antibodies were diluted in FACS buffer and applied to incubate for 30 min. For intracellular staining, cells were subsequently washed by FACS buffer and fixed (Fixation and Permeabilization Solution, BD Biosciences, BD554722), then the relevant fluorescent-labeled antibodies, diluted in Perm/Wash Buffer (BD Biosciences, BD557885), were used to incubate for 30 min. Upon staining, cells were resuspended in FACS buffer (25 mM HEPES, 2% FBS, 10 mM EDTA, 0.1% sodium azide in PBS) and passed through 50um mesh filter before flow cytometry analysis. The stained cells were run on a BD LSRFortessa X-20 Flow Cytometer equipped with FACSDiva software (BD Biosciences). FlowJo software (Treestar) was applied for analyzing flow cytometry data. Forward scatter (FSC) and side scatter (SSC) were used to gate on single nucleated cells and to eliminate cell debris and doublets.
Immunoblotting and ELISA assay. THP-1 and RAW264.7 cell lines were cultured in RPMI-1640 medium supplemented with 10% FBS. After treatment with indicated shRNA lentivirus or pcDNA3.1 plasmid vectors, THP-1 and RAW264.7 cells were harvested in RIPA buffer (Sigma-Aldrich) supplemented with protease inhibitors and phosphatase inhibitors (Roche). Next, equal amounts of total protein lysates (40 µg) were separated by SDS-PAGE before transferred to a PVDF microporous membrane, and stained with antibodies against TMSB10 (1:1000, Sant cruz, sc-514309), AKT (1:1000, Abcam, ab8805), p-AKT(Ser473) (a1:3000, Abcam, ab81283), mTOR (1:2000, Abcam, ab2732) p-mTOR(sec2448) (1:1000, Abcam, ab109268), p70S6K (1:2000, CST, 9202S), p-p70S6K(Thr389) (1:1000, CST, 9234T) and GAPDH (1:5000,CST, 5174S) as previously described (18). Meanwhile, the extracellular IL-6, IL-10 and TNF-α level in serum-free conditioned media from THP-1 and RAW264.7 cells treated with indicated lentivirus (1 µg) or LPS (100 ng/ml) for 72 hr were measured using the human ELISA kit (Elabscience, Wuhan).
Immunohistochemistry. Immunohistochemical assay was performed on the 5 mm thick slides, using mouse anti-human TMSB10 (1:500, Sant cruz, sc-514309) and CD68 (1:1000, CST, 76437) primary antibody, as previously (22). Two experienced investigator independently scored the TAMs-associated TMSB10 without knew the clinical data. The proportion of positive macrophage was scored as 0 (0–9% positive macrophages), 1 (10–25% positive macrophages), 2 (26–50% positive macrophages) and 3 (> 50% positive macrophages) respectively. Staining intensity was scored as 0 (no staining), 1 (weak staining), 2 (moderate staining) and 3 (strong staining). The final scores ranged from 0 to 3, ≥ 2 score was defined as high TAMs-associated TMSB10 expression and < 2 score was defined as low TAMs-associated TMSB10 expression according to previous method (17).
Cell counting Kit-8 (CCK8)
The THP-1 and RAW264.7 cell proliferation were measured by a CCK-8 kit (Beyotime, Shanghai, China). Briefly, cells were seeded into 96-well plates. After transfection of indicated shRNA lentivirus for 72 hr, the WST-8 reagent was added to each well for 1 hr incubation. The optical density (OD) value (450 nm) was measured using a microplate reader.
Statistical analysis. Statistical analyses were performed by SPSS 22.0 software (IBM Corporation, NY, USA). The correlation between TMSB10 expression and clinical pathological variables were investigated by Chi-square test. The Kaplan-Meier method and Cox proportional hazard model were used to investigate the prognostic factors for progression free survival (PFS) and overall survival (OS). Unpaired two-tailed Student’s t tests and/or analysis of variance (ANOVA) were used to calculate the significance. P < 0.05 was considered significant unless otherwise noted.