Poster Presentation 14th International Biennial Conference on Metastasis Research 2012

The antimicrobial peptide LL-37 inhibits migration of the prostate cancer PC-3 and DU145 cell lines  (#200)

Yan Tu 1 , Cameron Johnstone 2 , Alastair G Stewart 1
  1. University of Melbourne, Parkville, VIC, Australia
  2. Peter MacCallum Cancer Centre, East Melbourne , VIC, Australia

Introduction, Prostate cancer is the most commonly diagnosed cancer in Australia. The progression of the disease is usually protracted and most men diagnosed ultimately die of other causes. However, when metastases occur, metastatic progression is rapid and often resistant to therapeutic intervention. The human cathelicidin-derived antimicrobial peptide (hCAP18), LL-37 exhibits potent immune-regulatory activities independently of its anti-microbial actions and is found in prostatic fluid in high concentrations. hCAP18/LL-37 is implicated in lung, breast, and ovarian cancer cell migration.

Aims, To characterise the impact of LL-37 on prostate cancer cell migration.

Methods, The effect of LL-37 on the prostate cancer PC-3 and DU145 cell migration was assessed using an in vitro scrape injury wound closure assay, and a modified Boyden chamber assay. The receptor dependence of the LL-37 effects on the wound closure assay was probed using agonists and antagonists of the formyl peptide receptor (FPR2), purinoceptors and the epidermal growth factor receptor (EGFR) kinase. The impact of LL-37 on proliferation was investigated to ascertain whether the impact of the LL-37 on wound closure was secondary to proliferation.

Results, LL-37 (0.1nM to 1000nM) alone had no influence on the migration of PC-3 and DU145 cells. However, LL-37 (0.1nM to 10μM) inhibited serum-induced wound closure and chemotaxis. LL-37 had no impact on PC-3 proliferation, indicating that proliferation is not a contributing factor to the LL-37 effect on wound closure. A high concentration of LL-37 (10μM) exerted cytotoxic effect on DU145 cells, but not PC-3 cells. The effect of LL-37 on wound closure was mimicked by purinoceptor agonist, ATP and FPR2 peptide ANXA2-26, but not by EGF. However, attenuation of serum-induced wound closure by LL-37 was insensitive to pre-treatment by the FPR2 receptor antagonist BOC2 (100nM). Moreover, PCR analysis showed only very low levels of FPR2 receptor expression in PC-3 cells, further reducing the likelihood of involvement of FPR2 in the actions of LL-37.

Discussion, Our findings are consistent with the possibility that LL-37 reduces PC-3 migration by actions at a purinoceptor. Impairment of prostate cancer cell migration in vivo may engender an anti-metastatic effect of LL-37.