Human papillomavirus type 16 E6 oncoprotein promotes proliferation and invasion of non-small cell lung cancer cells through Toll-like receptor 3 signaling pathway.

Human papillomavirus (HPV) oncoproteins play vital roles in non-small cell lung cancer (NSCLC) pathogenesis, and Toll-like receptors (TLRs) contribute to tumor progression. However, interaction between HPV oncoproteins and TLR signaling in NSCLC progression remains unclear. Thus, the aim of the study was to explore effects of HPV16 E6 oncoprotein-induced TLRs pathway on growth and invasion of NSCLC cells and to examine potential mechanisms being involved. Recombinant plasmid (pcDNA-HPV16 E6) expressing HPV16 E6 protein was constructed. The expression prolife of TLRs was measured in NSCLC cell line A549 with or without pcDNA-HPV16 E6 transfection by real-time reverse polymerase chain reaction and Western blot. Cellular proliferation, invasion, cytokine productions, and downstream signaling pathways were also examined in TLR3-silencing/pcDNA-HPV16 E6 transfect A549 cells. Overexpression of HPV16 E6 increased proliferation, invasion, proliferation cytokine secretion, and TLR3 expression of A549 cells, while TLR3 silence inhibited HPV16 E6-induced tumor bioactivities of A549 cells. Down-regulation of TLR3 suppressed HPV16 E6-induced phosphorylation of Src, but did not affect TRIF expression. Moreover, inhibition of Src pathway also suppressed proliferation and invasion of A549 cells. In conclusion, HPV16 E6 oncoprotein promoted the bioactivities of NSCLC cells. TLR3-Src signaling pathway might be involved in this procession by up-regulation of cytokine production. The interaction between HPV16 E6 protein and TLR3 might contribute to the poor prognosis of NSCLC.