[A study on the association of telomere length with the experimental carcinogenesis of oral cavity].
OBJECTIVE
The life cycle of cell can be effected by the length of telomere. Loss of telomeric DNA during cell proliferation may play a role in chromosome instability, cellular apoptosis and cancer. The purpose of the study is to measure the dynamic changes of telomere length in experimental oral cavity cancer during golden hamster cheek pouch carcinogenesis induced by DMBA.


METHODS
First, 52 golden hamsters were divided into 2 groups. Four of them were not done any treatment and were killed after 3 days. The others were covered with DMBA on the surface of cheek pouch on one side in order to induce carcinogenesis, the other side of cheek pouch was treated as the control. Then, the 48 golden hamsters were divided into 4 groups and were killed in 7, 10, 14, 20 weeks. Light microscope was used to observe the pathologic changes. Southern hybridization was used to analysis the dynamic development of the length of telomeric repeat. In different periods, the reduction rate of telomere length was calculated.


RESULTS
1. The cheek pouch mucosa uncovered with DMBA had no abnormal pathologic changes, while that covered with DMBA was observed pathologic changes of different degrees. 4 cases of hyperplasia lesions and 8 cases of dysplasia lesions were observed in the 7-week group, 7 cases of dysplasia lesions and 5 cases of mucosa carcinoma in situ in the 10-week group, 5 cases of mucosa carcinoma in situ, 4 cases of squamous cell carcinomas and 3 cases of death in the 14-week group, and 7 cases of squamous cell carcinomas and 5 cases of death in the 20-week group. 2. The telomere length of the normal mucosa was reduced with the hamsters age increasing, but the telomere length was significantly shorter than that of the normal control during the mucosa carcinogenesis of cheek pouch. The average shortened length was about 0.225 kb (the normal mucosa was 0.17 kb). 3. The highest reduction rate (0.3985) was in a later premalignant period.


CONCLUSIONS
Age is one of the factors that can short telomere length. However, the speed that telomere length is shorted is faster than ever while telomere is abnormal. There is an obvious relationship between the abnormal degree of telomere length and the malignant degree of carcinoma. So the abnormal shorting of telomere length is an early molecular evidence of the oral carcinogenesis.
Gao
Z
Z
Department of Oral Maxillofacial Surgery, College of Stomatology, West China University of Medical Sciences.
Mao
Z
Z
He
Y
Y
Xu
P
P
D000818:Animals; D002294:Carcinoma, Squamous Cell / Q000235:genetics*; D006224:Cricetinae; D008647:Mesocricetus; D009062:Mouth Neoplasms / Q000235:genetics*; D011230:Precancerous Conditions / Q000235:genetics; D016615:Telomere / Q000235:genetics*