Phospho-Akt pathway activation and inhibition depends on N-cadherin or phospho-EGFR expression in invasive human bladder cancer cell lines.
OBJECTIVE
A particular interest in epithelial-mesenchymal transition (EMT), which takes place during embryonic development, provided potential mechanisms involved in the progression of many epithelial tumors, including bladder cancer (BC). The phospho-Akt signaling pathway is supposed to be involved in invasion and progression of human tumors, including BC. Moreover, it has been demonstrated in bladder cancer cell lines that N-cadherin or phospho-epithelial growth factor receptor (EGFR) expression are correlated to tumor progression. Our objectives were to evaluate the potential phospho-Akt pathway involvement in N-cadherin and/or phospho-EGFR positive BC cell lines and to evaluate the prognostic value of E- and N-cadherin expression in patients undergoing cystectomy for invasive BC.


METHODS
We screened a panel of invasive and noninvasive BC cell lines for E- and N-cadherin, phospho-EGFR, and phospho-Akt expression using the Western blot technique (WB). The potential role of N-cadherin in invasion was assessed by Matrigel assays with and without the N-cadherin blocking monoclonal antibody GC-4. Then we used the Affymetrix microarray technique to evaluate the prognostic value of E- and N-cadherin expression in 30 patients undergoing a cystectomy for invasive BC.


RESULTS
N-cadherin and phospho-EGFR expression are associated with Akt activation and with invasive behavior modulation. Even if Akt activation is sufficient in promoting invasion, its inactivation by LY294002 (PI-3 kinase inhibitor) is less efficient on invasion than inhibition of N-cadherin and phospho-EGFR by GC-4 (monoclonal antibody) and gefitinib (anti-tyrosine kinase), respectively. N-cadherin and phospho-EGFR inhibition decreased phospho-Akt activation but also caused restoration and reinforcing of E-cadherin expression, respectively, while phospho-Akt inhibition did not have any impact on E-cadherin expression. In a group of high-risk bladder tumors (T(1)G(3)), N- and E-cadherin expression could be considered as a prognostic marker. In a group of patients with invasive BC (pT(2)-T(4)) undergoing cystectomy, we showed a shorter overall survival when BC expressed N-cadherin (P = 0.0064) and when E-cadherin expression was down-regulated (P = 0.00165). The N (positive) /E (negative) profile has the worst prognosis (P = 0.00153).


CONCLUSIONS
We confirmed the partial responsibility of p-Akt activation in invasion of some BC cell lines expressing N-cadherin or p-EGFR and also the potential role of N-cadherin and p-EGFR as target in cancer therapy. N/E- cadherin expression profile has a significant prognostic value in invasive BC.
Wallerand
Hervé
H
Department of Urology, CHU Pellegrin, Victor Segalen School of Medicine, Bordeaux, France. herve.wallerand@chu-bordeaux.fr
Cai
Ying
Y
Wainberg
Zev A
ZA
Garraway
Isla
I
Lascombe
Isabelle
I
Nicolle
Gaëlle
G
Thiery
Jean-Paul
JP
Bittard
Hugues
H
Radvanyi
François
F
Reiter
Robert R
RR
D014408:Biomarkers, Tumor / Q000032:analysis; D015153:Blotting, Western; D015820:Cadherins / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D066246:ErbB Receptors / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D020869:Gene Expression Profiling; D006801:Humans; D053208:Kaplan-Meier Estimate; D009361:Neoplasm Invasiveness / Q000235:genetics; D020411:Oligonucleotide Array Sequence Analysis; D010766:Phosphorylation; D011379:Prognosis; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology*; D001749:Urinary Bladder Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology
D014408:Biomarkers, Tumor; D015820:Cadherins; D066246:ErbB Receptors; D051057:Proto-Oncogene Proteins c-akt