Objective  To investigate the expression of Toll-like receptor 4 (TLR4) in human lymphoma cell lines and its effect on cell proliferation and drug resistance.

Methods  Eight lymphoma cell lines were detected by RT-PCR, qPCR and Western blot to select the one with highest mRNA and protein expression of TLR4. Gene sequencing of the high expression cell line was detected to exclude MyD88 L265P gene mutation. Cell proliferation and doxorubicin resistance test of the TLR4 high expression cell line were carried out by blank control group, TAK-242 group, Lipopolysaccharides (LPS) group and LPS+TAK-242 group, respectively. CCK-8 kit was used to detect the proliferation activity and cell death rate, and Western blot was used to detect the changes of proliferating cell nuclear antigen (PCNA) and P-glycoprotein (P-gp).

Results  TLR4 mRNA and protein were expressed in eight lymphoma cell lines, and the Burkitt lymphoma cell line Raji was the highest. MyD88 gene in Raji was wild type. Compared with the blank control group, the proliferation of TAK-242 group and LPS+TAK-242 group wasn’t increased significantly (P=2.19, P=1.85) ; the proliferation of LPS group was increased significantly (P=0.016) . The expression of PCNA protein was significantly increased in the LPS group (P=0.009) . Cell death rate of each group in the half inhibitory concentration of doxorubicin: blank control group (49.23±2.03) %, TAK-242 group (51.41±1.12) %, LPS group (24.65±3.17) %, and LPS+TAK-242 group (41.17±2.69) %. The cell death rate of LPS group was significantly lower (P=0.002) . The expression of P-gp protein was significantly higher (P=0.001) .

Conclusion  TLR4 is widely expressed in lymphoma cell lines, especially in Burkitt lymphoma cell line Raji. The activation of TLR4 can induce tumor cell proliferation and drug resistance, and its mechanism may be related to the upregulation of PCNA and P-gp expression.