The Differential Expression of EphB2 and EphB4 Receptor Kinases in Normal Bladder and in Transitional Cell Carcinoma of the Bladder

Abstract

Effective treatment of transitional cell carcinoma (TCC) of the bladder requires early diagnosis. Identifying novel molecular markers in TCC would guide the development of diagnostic and therapeutic targets. Ephrins mediate signals via tyrosine kinase activity that modulates diverse physiologic and developmental processes, and ephrins are increasingly implicated in carcinogenesis. The aim of our study was to examine the differential regulation of EphB4 and EphB2 in normal bladder and in TCC of the bladder in 40 patients undergoing radical cystectomy for curative intent. Immunostaining and Western blotting revealed that normal urothelium expresses EphB2 (20 of 24 cases, 83% of the time) not EphB4 (0 of 24 cases, 0%). In sharp contrast, TCC specimens show loss of EphB2 expression (0 of 34 cases, 0%) and gain of EphB4 expression (32 of 34, 94%). Furthermore, EphB4 signal strength statistically correlated with higher tumor stage, and trended toward the presence of carcinoma in situ (CIS). These results are confirmed by analysis of normal urothelial and tumor cell lines. EphB2 is not a survival factor in normal urothelium, while EphB4 is a survival factor in TCC. Treatment of bladder tumor xenograft with an EphB4 inhibitor sEphB4-HSA leads to 62% tumor regression and complete remission when combined with Bevacizumab. Furthermore, tissue analysis revealed that sEphB4-HSA led to increased apoptosis, decreased proliferation, and reduced vessel density, implicating direct tumor cell targeting as well as anti-angiogenesis effect. In summary loss of EphB2 and gain of EphB4 expression represents an inflection point in the development, growth and possibly progression of TCC. Therapeutic compounds targeting EphB4 have potential for diagnosing and treating TCC.

Ephrin-B1 Is a Novel Biomarker of Bladder Cancer Aggressiveness. Studies in Murine Models and in Human Samples

“…Based on these findings, EphB2 expression was evaluated in total protein cell extracts, finding 3 times higher levels in MB49-I cells than in MB49 cells ( Figure 4G). These findings are in agreement with the association reported between high EphB2 expression and EMT induction and progression of human cervical cancer (69), although they contrast with a report describing its decrease in human BC samples (70).…”

EphB2 Promotes Progression of Cutaneous Squamous Cell Carcinoma

“…In contrast, activation of EphB2 has been shown to promote invasion of glioblastoma in vivo (Wang et al, 2012). In transitional cell carcinoma of the bladder, loss of EphB2 and gain of EphB4 expression have been reported to be associated with the tumor progression, and EphB4 inhibitors have been shown to have antitumor properties in xenograft model of this tumor (Li et al, 2014). Previous studies on the role of Eph/ephrin signaling in the progression of skin cancer have identified members of EphA subfamily, especially EphA2, as tumor suppressor in epidermal keratinocytes (Guo et al, 2006b).…”

Targeting Forward and Reverse EphB4/EFNB2 Signaling by a Peptide with Dual Functions

“…Both EphB4 and its sole physiologically relevant ligand, ephrin B2 (EFNB2), are membrane bound, and their interaction initiates forward signaling through EphB4 and reverse signaling through EFNB2 1 . EphB4 is overexpressed in many solid tumors, including those of the ovary 2,3 , breast 4,5 , colon 6 , prostate 7,8 , and bladder 9 . High EphB4 expression is associated with shorter disease-free survival in patients with epithelial ovarian cancer 3,10 .…”