[hTERT promoter enhances the radiosensitivity to gene-radiation therapy of human laryngeal carcinoma transplanted in nude mice].
OBJECTIVE
To explore the therapeutic efficiency of human telomerase reverse transcriptase promoter (hTERTp) mediated horseradish peroxidase (HRP) catalyzed effects of indole-3-acetic (IAA) on laryngeal squamous cell carcinoma with different radiosensitivity in vivo.


METHODS
Human laryngeal squamous cell carcinoma Hep-2 and Hep-2R cells were transplanted into nude mice. After growing to about 30 approximately 50 mm3, the tumor-bearing mice were randomly divided into eight groups: Hep-2 line: combined group (A), gene group (B), radiation group (C) and blank group (D); Hep-2R line: combined group (AR), gene group (BR), radiation group (CR) and blank group (DR). The phTERTp-HRP was delivered by intratumoral injection and the IAA by intraperitoneal injection, combined with 2 Gy daily radiation to a total dose of 30 Gy. The tumor volume was recorded. The cell apoptosis was detected by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) assay. The expression of HRP protein was detected by AP immunohistochemisty.


RESULTS
The tumor growth of combined groups was attenuated significantly and the tumor volume of Hep-2R blank group was the largest. The inhibition rate of each group was: A: 54.8%, B: 10.0%, C: 31.9%; AR: 52.7%, BR: 24.8%, CR: 17.0%. In the combined groups, necrosis and apoptosis of tumor cells were observed under the light microscope and the apoptotic index [A (16.6 +/- 1.3)% vs. AR (17.6 +/- 1.3)%] of tumor cells was highest (P < 0.05). The HRP protein expression of BR (33.3 +/- 8.9)% was higher than that of B (21.9 +/- 5.7)%, which was directly up-regulated in the tumors (45.0% vs. 54.8%, P < 0.05) after radiation.


CONCLUSIONS
In the Hep-2- and Hep-2R-transplantation tumors in nude mice, hTERTp can be induced by radiation and enhance the expression of horseradish peroxidase (HRP) gene according to telomerase activity. hTERTp-HRP/IAA system, which has synergistic effects with radiation and inhibits the tumor growth by induction of apoptosis and necrosis, may be a new gene-radiation strategy for the treatment of laryngeal carcinoma.
Huang
Cheng-hu
CH
Department of Radiation & Medical Oncology, Zhongnan Hospital of Wuhan University, Wuhan 430071, China.
Liao
Zheng-kai
ZK
Zhou
Fu-xiang
FX
Wang
Wei-feng
WF
Xie
Cong-hua
CH
Zhang
Hong-yan
HY
Sun
Wen-jie
WJ
Zhou
Yun-feng
YF
D000818:Animals; D017209:Apoptosis; D045744:Cell Line, Tumor; D003131:Combined Modality Therapy; D005260:Female; D015316:Genetic Therapy / Q000379:methods*; D006735:Horseradish Peroxidase / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D007210:Indoleacetic Acids / Q000378:metabolism / Q000494:pharmacology; D007822:Laryngeal Neoplasms / Q000378:metabolism / Q000473:pathology / Q000628:therapy*; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D011401:Promoter Regions, Genetic; D011836:Radiation Tolerance; D011878:Radiotherapy / Q000379:methods*; D011897:Random Allocation; D019098:Telomerase / Q000235:genetics*; D047368:Tumor Burden
D007210:Indoleacetic Acids; C030737:indoleacetic acid; D006735:Horseradish Peroxidase; C509186:TERT protein, human; D019098:Telomerase