Login to Access Video or Poster Abstract: MP98-17
Sources of Funding: This research was supported by the Intramural Research Program of the NIH, National Cancer Institute, Center for Cancer Research. This research was also made possible through the NIH Medical Research Scholars Program, a public-private partnership supported jointly by the NIH and generous contributions to the Foundation for the NIH from the Doris Duke Charitable Foundation, the American Association for Dental Research, the Colgate-Palmolive Company, Genentech, and other private donors. For a complete list, visit the foundation website at http://www.fnih.org.

Introduction

Protein Kinase D (PKD) is downstream of protein kinase C and it can regulate cell survival, proliferation, invasion, and migration. It has been implicated in several cancers and exists in three major isoforms. We sought to investigate the role of PKD2 in bladder cancer.

Methods

PKD2 protein expression was assessed using Oncomine data for normal urothelium and bladder tumors. Several bladder cancer cell lines (T24, T24T, UMUC1, and TCCSUP) were assessed for cell proliferation, growth in low attachment agar (GILA), invasion, and migration with and without stable knock-down of PKD2. The UMUC1 cell line was evaluated in xenografts for tumor growth with and without stable knock-down of PKD2. A flank xenograft experiment was performed with oral gavage in mice using CRT0066101, a pan-PKD inhibitor. Western blot analysis was used to confirm silencing and evaluate downstream targets of PKD2.

Results

Oncomine data confirmed increased mRNA expression of PKD2 in bladder tumors compared with normal urothelium. Selective knock-down of PKD2 in the cell lines inhibited cell proliferation, GILA colony formation, invasion, and migration. UMUC1 cells with silenced PKD2 failed to grow tumors in xenografts. Tumor xenografts treated with CRT0066101 had significant tumor growth inhibition compared to tumor controls (p<0.0001). Loss of phosphorylated c-Jun, a key mediator of cell proliferation and apoptosis, is noted with PKD2 silencing and PKD pharmacologic inhibition.

Conclusions

PKD2 is overexpressed in bladder tumors and inhibition of PKD2 either through selective silencing of PKD2 or the use of a pan-PKD inhibitor results in tumor growth inhibition in cell lines and xenografts. Targeting PKD2 results in loss of active c-Jun and may represent a therapeutic strategy in urothelial cancer.

Funding

This research was supported by the Intramural Research Program of the NIH, National Cancer Institute, Center for Cancer Research. This research was also made possible through the NIH Medical Research Scholars Program, a public-private partnership supported jointly by the NIH and generous contributions to the Foundation for the NIH from the Doris Duke Charitable Foundation, the American Association for Dental Research, the Colgate-Palmolive Company, Genentech, and other private donors. For a complete list, visit the foundation website at http://www.fnih.org.