Heparin-binding epidermal growth factor-like growth factor isoforms and epidermal growth factor receptor/ErbB1 expression in bladder cancer and their relation to clinical outcome.
BACKGROUND
Cleavage of membrane-anchored heparin-binding epidermal growth factor-like growth factor (proHB-EGF) yields a soluble HB-EGF isoform (sHB-EGF), which is an activating epidermal growth factor receptor (EGFR) ligand and a C-terminal fragment HB-EGF-C acting directly in the nucleus. In bladder cancer, overexpression of both HB-EGF and EGFR have been observed, but to the authors' knowledge the prognostic significance of different modes of HB-EGF signaling have remained unclear.


METHODS
Expression and intracellular localization of HB-EGF and EGFR were examined by immunohistochemistry in paraffin-embedded specimens from 121 patients who underwent cystectomy for bladder cancer. Tumor stage was pTis/pT1 in 7 patients, pT2 in 41 patients, pT3 in 55 patients, and pT4 in 18 patients. Lymph node metastases were present in 32 patients.


RESULTS
Using an antibody directed against the C-terminal domain, HB-EGF expression was detected in the cytoplasm or in the nucleus of tumor cells. EGFR staining was uniform at the plasma membrane. The actuarial 5-year cancer-specific survival of patients with tumors with predominant nuclear HB-EGF staining was 28% compared with 57% if HB-EGF staining was predominantly cytoplasmic (P = .027). Disease outcome of patients with a 'mixed' HB-EGF staining pattern was found to be between that of the 2 former groups. In agreement with previous studies, strong EGFR expression was associated with poor prognosis. Despite strong EGFR expression, predominant cytoplasmic HB-EGF staining was associated with a more favorable outcome, whereas a predominant nuclear pattern defined a subgroup with extremely poor prognosis (5-year tumor-specific survival of 55% vs 13%, respectively; P = .026).


CONCLUSIONS
The current study results confirm that EGFR expression is significantly correlated with disease-specific mortality but that the outcome is also influenced by the mode of HB-EGF signaling. Additional nuclear HB-EGF signaling, indicative of increased cleavage of proHB-EGF, appears to enhance the adverse activities. Cytoplasmic HB-EGF staining likely reflects proHB-EGF, which may also exert antiproliferative effects.
Kramer
Christopher
C
Department of Urology, Heinrich-Heine University, Dusseldorf, Germany.
Klasmeyer
Kai
K
Bojar
Hans
H
Schulz
Wolfgang A
WA
Ackermann
Rolf
R
Grimm
Marc-Oliver
MO
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000032:analysis; D002295:Carcinoma, Transitional Cell / Q000378:metabolism* / Q000401:mortality / Q000473:pathology / Q000628:therapy; D002467:Cell Nucleus / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D004815:Epidermal Growth Factor / Q000378:metabolism*; D066246:ErbB Receptors / Q000378:metabolism*; D005260:Female; D066257:Heparin-binding EGF-like Growth Factor; D006801:Humans; D007150:Immunohistochemistry; D036341:Intercellular Signaling Peptides and Proteins; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D015996:Survival Rate; D001749:Urinary Bladder Neoplasms / Q000378:metabolism* / Q000401:mortality / Q000473:pathology / Q000628:therapy
D014408:Biomarkers, Tumor; C587883:HBEGF protein, human; D066257:Heparin-binding EGF-like Growth Factor; D036341:Intercellular Signaling Peptides and Proteins; D004815:Epidermal Growth Factor; D066246:ErbB Receptors