I-Ling Lee

BACKGROUND: p63 is a member of the p53 family that has been implicated in maintenance of epithelial stem cell compartments. Previous studies demonstrated that p63 is downregulated in muscle-invasive bladder cancers, but the relationship between p63 expression and survival is not clear. METHODOLOGY/PRINCIPAL FINDINGS: We used real-time PCR to characterize p63 expression and several genes implicated in epithelial-to-mesenchymal transition (EMT) in human bladder cancer cell lines (n = 15) and primary tumors (n = 101). We correlated tumor marker expression with stage, disease-specific (DSS), and overall survival (OS). Expression of E-cadherin and p63 correlated directly with one another and inversely with expression of the mesenchymal markers Zeb-1, Zeb-2, and vimentin. Non-muscle-invasive (Ta and T1) bladder cancers uniformly expressed high levels of E-cadherin and p63 and low levels of the mesenchymal markers. Interestingly, a subset of muscle-invasive (T2-T4) tumors maintained high levels of E-cadherin and p63 expression. As expected, there was a strongly significant correlation between EMT marker expression and muscle invasion (p<0.0001). However, OS was shorter in patients with muscle-invasive tumors that retained p63 (p = 0.007). CONCLUSIONS/SIGNIFICANCE: Our data confirm that molecular markers of EMT are elevated in muscle-invasive bladder cancers, but interestingly, retention of the "epithelial" marker p63 in muscle-invasive tumors is associated with a worse outcome.

Chromosomal aneuploidy is associated with invasive bladder cancer and one of the genes implicated in these changes is Aurora-A/STK15/BTAK, that is localized on chromosome 20q13 and encodes a centrosome-associated serine/threonine kinase. To better understand the association between Aurora-A/STK15 expression, tumor aneuploidy and clinical prognosis, we sought to determine whether overexpression of Aurora-A/STK15 in cultured urothelial cells facilitated chromosomal instability. Using immunofluorescence staining, Northern and Western blot analyses, we verified that overexpression of Aurora-A/STK15 in bladder tumor cell lines enhanced chromosomal instability. Additionally, we observed that some bladder tumor cell lines expressed more Aurora-A/STK15 than cultured normal urothelial cells and that Aurora-A/STK15 expression was higher in an immortalized E7 urothelial cell line having 20q amplification than in an E6 line lacking 20q amplification. These results were consistent with our observations of higher mRNA levels in some T3 invasive bladder tumors than in T1 superficial tumors and adjacent normal bladder tissue. Overall our results suggest that overexpression of Aurora-A/STK15 in bladder tumor cells contributes to tumor progression by promoting chromosomal instability leading to aneuploidy.