[Telomerase antisense inhibition and chemotherapeutic combination treatments for the proliferation of endometrial cancer in vitro and in vivo].

OBJECTIVE

To investigate the antitumor effects of telomerase antisense oligodeoxynucleotide (AODN).

METHODS

Human endometrial cancer cells of HEC-1A line were cultured at the concentrations of 0.8 and 1.6 micromol/L respectively and transfected with human telomerase AODN, as telomerase inhibitors, twice. 24, 48, 72, 96, and 128 hours after the first transfection MTT method was used to detect the absorbance at the wave length of 490 nm so as to determine the cell survival rate. HEC-1A cells were collected after transfection of 0.05, 0.1, 0.2, 0.4, and 0.8 micromol/L of AODN and the total DNA was extracted. Reverse transcription-polymerase chain reaction (RT-PCR) was used to examine the expression of hTERT mRNA. Telomeric repeat amplification protocol (TRAP)-ELISA was used to detect the activity of telomerase. HEC-1A cells were injected subcutaneously into the axillary fossae of Balb/c nude mice, Four days after when tumors were touchable the nude mice were divided into 5 groups to undergo intratumoral injection of high-dosage ADON (25 mg/kg, 1/d), low-dosage ADON (12.5 mg/kg, 1/d), cis-dichlorodiamine plastinum (DDP, cisplatin, 12.5 mg/kg, 1/d), AODN + DDP (AODN 12.5 mg/kg and DDP 5 microg/kg, 1/d alternatively), and normal saline respectively. The tumor size, tumor weight, and tumor relative volume were measured and calculated. Twenty-one days after the mice were killed and their organs were examined.

RESULTS

AODN effectively and dose-dependently inhibited the growth of HEC-1A cells. There was a plateau of inhibition. The inhibition rate rose further 4 days after transfection. Five days after transfection the proliferation inhibition rate of AODN of the concentrations of 0.4, 0.8, and 1.6 microm were 46.35%, 65.22%, and 79.45% respectively. The relative inhibition rate of hTERT mRNA expression increased dose-independently along with the increase of concentration of transfected AODN. The tumor inhibition rate of nude mice were 34.20%, 89.21%, 79.82%, and 72.41% in the low-dosage AODN group, high-dosage AODN group, DDP group, and AODN + DDP group respectively. However, AODN began to show significant inhibitory effect 8 days after administration. The tumor inhibition rate of the AODN+DDP group was 72.4%, similar to those of the high dosage AODN and DDP groups (both P < 0.05). The telomerase activity in tumor of the AODN (25 mg/kg) group was 509 +/- 377, decreased by 87.23% in comparison with that of the control group (64 +/- 23, P < 0.05).

CONCLUSION

Antisesne oligonucleotide of hTERT effectively inhibits the abnormal activation of telomerase, thus the growth of endometrial cancer cells. Telomerase inhibitor may be a new strategy for chemotherapy or chemoprevention in endometrial cancer.