Background & objective: The expression of Survivin in cancer cells highly correlates with that of human telomerase reverse transcriptase (hTERT). Both of them are ideal targets for cancer gene therapy. This study aimed to clarify if they regulate each other in cancer cells.
Methods: The expressions of Survivin and hTERT in HeLa S3 cells were inhibited by antisense oligonucleotide respectively. Activity of telomerase was detected by telomerase repeat amplification (TRAP) assay. Protein and mRNA levels of Survivin were analyzed by Western blot and reverse transcription-polymerase chain reaction (RT-PCR) respectively. Proliferation of HeLa S3 cells was analyzed by MTT assay.
Results: Inhibiting the expression of Survivin in HeLa S3 cells had no effects on telomerase activity. Inhibiting the expression of hTERT by antisense oligonucleotide No.14 decreased protein level of Survivin, which was negatively correlated with the concentration of No.14 (200-1 000 nmol/L), but didn't change mRNA level of survivin. The decrease of Survivin level was inhibited by proteasome inhibitor lactacystin and MG132. Furthermore, simultaneous inhibition of hTERT and survivin co-efficiently inhibited proliferation of HeLa S3 cells.
Conclusion: Inhibiting the expression of hTERT in HeLa S3 cells promotes ubiquitin-proteasome degradation of Survivin.