Login to Access Video or Poster Abstract: MP88-06
Sources of Funding: None

Introduction

Emerging preclinical evidence has indicated the involvement of AR signaling in urothelial tumorigenesis. Meanwhile, cross-talk between AR and NF-&[kappa]B, a protein complex of transcriptional factor and its phosphorylation is required for optimal induction of target genes, has been demonstrated in prostate cancer cells. We therefore investigated the role of NF-&[kappa]B in neoplastic transformation of urothelial cells in relation to AR signaling.

Methods

We immunohistochemically stained for NF-&[kappa]B and phospho-NF-&[kappa]B (p-NF-&[kappa]B) in 149 bladder tumor and paired non-neoplastic bladder tissue specimens. Then, in immortalized human normal urothelial SVHUC sublines stably expressing AR with exposure to a chemical carcinogen 3-methylcholanthrene (MCA), we assessed the effects of NF-&[kappa]B activator (betulinic acid; BA) and inhibitor (parthenolide; PAR) on the expression of AR, NF-&[kappa]B p65 subunit, oncogenes, and tumor suppressors (via RT-PCR or western blot) as well as neoplastic transformation (via cell viability assay and plate/soft agar colony formation assays). Finally, N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) was given to male C57BL/6 mice to induce bladder tumors.

Results

NF-?B and p-NF-?B were positive in 100% [9% weak (1+), 40% moderate (2+), 51% strong (3+)] and 69% (44% 1+, 24% 2+, 1% 3+) of tumors, which was significantly elevated compared with non-neoplastic urothelial tissues [100% (25% 1+, 40% 2+, 35% 3+), P=0.016 (0/1+/2+ vs. 3+); and 46% (36% 1+, 10% 2+), P<0.001 (0 vs. 1+/2+/3+)]. Significantly higher rates of p-NF-&[kappa]B positivity were also seen in high-grade (76%, P=0.015) or muscle-invasive (78%, P=0.033) tumors than in low-grade (56%) or non-muscle-invasive (62%) tumors. In SVHUC-AR cells, BA induced and PAR reduced the expression of p65 and AR. Notably, BA accelerated and PAR prevented neoplastic transformation of MCA-SVHUC-AR cells, but not that of MCA-SVHUC cells. Additionally, in MCA-SVHUC-AR cells, BA up-regulated the expression of c-myc and down-regulated that of p53, p21, and UGT1A, while PAR showed the opposite results. Moreover, bladder tumors were identified in 56% (mock), 89% (BA), and 22% (PAR) of BBN-treated mice sacrificed at 21 weeks of age.

Conclusions

Compared with non-neoplastic urothelium, NF-&[kappa]B appeared to be activated in bladder cancer. In addition, NF-&[kappa]B modulators were found to involve the regulation of tumorigenesis in AR-activated urothelial cells. Accordingly, NF-&[kappa]B inhibition, together with AR inactivation, has the potential of being an effective chemopreventive approach for urothelial carcinoma.

Funding

None