Abstract: Objective To examine theexpression of TLRs in S180 osteosarcoma cells in vitro and at earlierandadvanced stages oftumor-bearing mouse in vivo; To reveal the expression ofTGF-β and IL-10 after stimulating the S180 osteosarcoma cells byLPS in vitro; Andto explorethe mechanisms oftumortolerance inducedby TLRsexpress in tumor cells. Methods S180 ascites carcinoma models were established. The expression of TLRs mRNA in S180 osteosarcoma cells in vitro, and at earlierand advanced stages of tumor-bearing mouse in vivoas well as the changes ofTGF-β and IL-10 after stimulating the S180 osteosarcoma cells byLPS were analyzed by semi-quantitative RT-PCR. The changes of TGF-β protein were detected by ELISA. Results S180 osteosarcoma cellscouldexpress TLR1~7and TLR 9，whilecouldn't express TLR8 in vitro. The expression ofTLR4and TLR9was higher in earlier stage than that in advanced stage. The expression of TLR4wasin significant difference in different stages(P＜0.05).Theexpress ofTLR1, TLR2, TLR3,TLR5,TLR6, andTLR7waslower in earlierstagethanthat in advancedstage, whileshowednosignificant difference(P＞0.05). Theexpression ofTGF-β andIL-10increasedand depended on time after stimulating S180 osteosarcomacells usingLPS at10μg/mllevel. Conclusion S180 in osteosarcoma cells couldexpress many kinds of TLRs,and the TLRs expression changed in different stage. Thus the express of TLRsin S180 osteosarcoma cellsplayed differentroles indifferent stagesduringthe development oftumor. The activation of TLR4 couldpromote the expression of TGF-β and IL-10,and then enhanced the tolerance of tumor cells.