Lymphotoxin β receptor activation promotes mRNA expression of RelA and pro-inflammatory cytokines TNFα and IL-1β in bladder cancer cells.

The role of inflammation in tumorigenesis and development is currently well established. Lymphotoxin beta receptor (LT beta R) activation induces canonical and noncanonical nuclear factor (NF)-kappa B signaling pathways, which are linked to inflammation-induced carcinogenesis. In the present study, 5,637 bladder cancer cells were cultured and the activation of LT beta R was induced by functional ligand, lymphotoxin (LT) alpha 1 beta 2, and silencing with shRNA. Reverse transcription-quantitative polymerase chain reaction was utilized to detect the mRNA expression levels of NF-kappa B family members RelA and RelB, cytokines including LT alpha, LT beta, tumor necrosis factor (TNF)alpha, TNF superfamily member 14, interleukin (IL)-6 and IL-1 beta, and proliferation-related genes including CyclinD1 and Survivin. The expression of phospho-p65 was determined by western blotting. Activation of LT beta R on bladder cancer 5,637 cells was demonstrated to upregulate the mRNA expression levels of the RELA proto-oncogene, RelA, by 2.5-fold compared with unstimulated cells, while no significant change was observed in the RELB proto-oncogene NF-kappa B member mRNA levels. Expression of pro-inflammatory cytokines tumor necrosis factor (TNF) a and interleukin (IL)-1 beta mRNA levels were significantly increased nearly 5-fold and 1.5-fold, respectively, following LT beta R activation compared with unstimulated cells. The LT beta R-induced upregulation of RelA, TNF alpha and IL-1 beta was decreased by similar to 33, 27, and 26% respectively when LT beta R was silenced via short hairpin RNA. Activation of LT beta R had no effect on 5,637 cell growth, despite CyclinD1 and Survivin mRNA levels increasing by similar to 2.7 and 1.3-fold, respectively, compared with unstimulated cells. In conclusion, activation of LT beta R induced the expression of RelA mRNA levels. LT beta R activation might be an important mediator in promoting an inflammatory microenvironment in bladder cancer, via the upregulation of TNF alpha and IL-1 beta mRNA levels. LT beta R may be a potential therapeutic target for bladder cancer.