Chemosensitization of bladder cancer cell lines by human telomerase reverse transcriptase antisense treatment.
OBJECTIVE
Responses of transitional cell carcinoma of the bladder (TCC) to commonly used chemotherapy agents such as mitomycin C (MMC), cisplatin and gemcitabine are often disappointing. Since human telomerase reverse transcriptase (hTERT) is tumor specifically expressed and contributes to the immortality and malignancy of the majority of tumors, it is regarded as a suitable antitumor target. We investigated whether combinations of hTERT antisense (AS)-oligonucleotides (ODNs) with common chemotherapy (CT) schedules may improve drug mediated antitumor effects.


METHODS
Initial screening for enhancement of the inhibitory effects of MMC, cisplatin and gemcitabine on viability by treatment with the 2 hTERT AS-ODNs ASt2206 and ASt2331 was performed in 4 TCC cell lines prior to CT. Apoptosis was assessed by annexin V staining and detection of activated caspase-3 using Western blot analysis. Nonsense (NS)-ODN served as a control in all experiments.


RESULTS
All cell lines responded to the anticancer agents tested. Treatment with AS plus CT resulted in a significantly stronger inhibition of viability than the NS plus CT control in the majority of combinations, indicating an AS specific enhancement effect. For example, ASt2331 plus MMC decreased viability to 17% in contrast to NS plus MMC (58%) in EJ28 cells. All ASt2331 plus CT combinations specifically increased the rate of apoptosis 1.3 to 3.0-fold compared with NS plus CT. Apoptosis induction was associated with caspase 3 activation.


CONCLUSIONS
Enhancement of cytotoxic drug effects on the growth of TCC cells by hTERT AS-ODNs presented herein allows a dose decrease in chemotherapy and confirms the suitability of hTERT as a target in a specific therapy approach.
Kraemer
Kai
K
Department of Urology, Technical University Dresden, Dresden, Germany.
Fuessel
Susanne
S
Kotzsch
Matthias
M
Ning
Shuangli
S
Schmidt
Uta
U
Wirth
Manfred P
MP
Meye
Axel
A
D002295:Carcinoma, Transitional Cell / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor; D004268:DNA-Binding Proteins; D004359:Drug Therapy, Combination; D006801:Humans; D016376:Oligonucleotides, Antisense / Q000494:pharmacology*; D019098:Telomerase / Q000187:drug effects*; D001749:Urinary Bladder Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology
D004268:DNA-Binding Proteins; D016376:Oligonucleotides, Antisense; D019098:Telomerase