[Inhibitory effect of recombinant transforming growth factor alpha-pseudomonas exotoxin 40 on human bladder cancer cell proliferation].
OBJECTIVE
To study inhibitory effect of recombinant transforming growth factor alpha-Pseudomonas exotoxin fusion protein (TP40) on proliferation of the human bladder cancer T24 cells.


METHODS
Expression of epidermal growth factor receptor (EGFR) in cultured T24 cells was analyzed with Western blot assay. Human bladder cancer T24 cells were exposed to TP40 at 5 - 1 000 microg/L. Methyl thiazolyl tetrazolium assay was applied to evaluate the cell proliferation by measuring the absorbance (A) at 570 nm with a microplate reader. Tritium labeled thymine deoxyriboside ([(3)H]-TdR) uptake was measured to observe DNA synthesis. Competition assays were performed by the EGF at 1 - 7 500 microg/L.


RESULTS
Expression of EGFR was high in human bladder cancer T24 cells. Cell growth was suppressed by 10%, 19%, 27%, 41%, 47%, 53% and 61% after 96 h treatment with TP40 at 5, 50, 100, 250, 500, 750 and 1 000 microg/L, respectively. [(3)H]-TdR incorporation was 80%, 69%, 48% and 51% after 24 h, 48 h, 72 h, 96 h treatment with TP40 at 750 microg/L, respectively. When the concentration was 1 - 7 500 microg/L, EGF could block the inhibitory effect of TP40 to some extent.


CONCLUSIONS
Human bladder cancer T24 cells express EGFR at a high level. TP40 could inhibit the growth of T24 cells effectively in a dose- and time-dependent manner. The cytotoxic effects of TP40 were specifically mediated by EGFR.
Yan
Xiang
X
Department of Urology, Huashan Hospital of Fudan University, Shanghai 200040, China. yanxiang126@126.com
Ding
Qiang
Q
Zhang
Yuan-fang
YF
Xu
Yong-hua
YH
D049109:Cell Proliferation / Q000187:drug effects; D066246:ErbB Receptors / Q000378:metabolism*; D005098:Exotoxins / Q000494:pharmacology*; D006801:Humans; D011993:Recombinant Fusion Proteins / Q000494:pharmacology*; D016211:Transforming Growth Factor alpha / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D001749:Urinary Bladder Neoplasms / Q000378:metabolism / Q000473:pathology*
D005098:Exotoxins; D011993:Recombinant Fusion Proteins; D016211:Transforming Growth Factor alpha; C083452:transforming growth factor alpha-Pseudomonas exotoxin A (40); D066246:ErbB Receptors