PLD1 promotes tumor invasion by regulation of MMP-13 expression via phosphorylation of NF-kB in bladder cancer

Invasion of bladder cancer (BC) cells from the mucosa into the muscle layer is canonical for BC progression while phospholipase D isoform 1 (PLD1) is known to mediate development of cancer through phosphatidic acid (PA) production. We therefore used in silico, in vitro and in vivo approaches to detail the effect of PLD1 on BC invasion. In BC patients, higher levels of PLD1 expression were associated with poor prognosis. PLD1 knockdown significantly suppressed cellular invasion by human BC cells and matrix metalloproteinase-13 (MMP-13) was observed to be an invasion mediator gene. In our mouse bladder carcinogenesis model, the development of invasive BCs was suppressed by PLD1 knockout and a global transcriptomic analysis in this model indicated MMP-13 as a potential tumor invasion gene with NF-kB (nuclear factor-kB) as its transcription regulator. Furthermore, PA administration increased both MMP-13 expression and NF-kB p65 phosphorylation levels. Collectively, we demonstrate that PLD1 promotes tumor invasion of BC by regulation of MMP-13 expression via phosphorylation of NF-kB p65. Our results suggest that PLD1 is a potential therapeutic target to prevent progression in BC patients. RNA sequencing was performed using the bladders from the wild-type and PLD1-knockout mice. Bladders were extracted from sacrificed animals at baseline and after 8, 12 and 16 weeks of treatment. All experiments were performed using triplet samples.