Expression of EphA2 and Ephrin A-1 in carcinoma of the urinary bladder

Purpose: The EphA2 receptor tyrosine kinase is believed to play a role in tumor growth and metastasis. The clinical significance of the expression of EphA2 was observed in breast, prostate, colon, skin, cervical, ovarian, and lung cancers. The purpose of this work was to determine the expression of EphA2 and its ligand, Ephrin A-1, and E-cadherin in carcinoma of the urinary bladder, and determine EphA2 as a new target for therapy in bladder cancer. Experimental Design: EphA2 mRNA and protein expression was investigated by reverse transcription-PCR and Western blot, respectively, in bladder cancer cell lines. In addition, the expression of EphA2, Ephrin A-1, and E-cadherin in tissues from patients with different stages of urinary bladder cancer was determined by immunohistochemistry. Furthermore, the ability of Ephrin A-1 to inhibit growth of bladder cancer cells was also investigated using an adenoviral delivery system. Results: Western blot analysis showed high EphA2 expression in TCCSUP, T24, and UMUC-3 cell lines. In tissues, the staining intensity of EphA2 was less in normal urothelium but increased greatly in advancing stages of urothelial carcinoma (P < 0.05). Similarly, the staining intensity of Ephrin A-1 was low in normal tissues and high in cancerous tissues, but it was similar across the various stages of urothelial carcinoma (T_a-T₄). E-cadherin immunoreactivity decreased in urothelial cancer. Association of EphA2 and Ephrin A-1 expression was found to be significant between T_a stage and T₁-T₂ (P < 0.04) and T_a and T ₃-T₄ stages (P < 0.0001). Adenovirus delivery of Ephrin A-1 inhibited proliferation of TCCSUP cells. Conclusion: EphA2 may serve as a novel target for bladder cancer therapy.