The effect of antisense hTERT mRNA oligodeoxynucleotide on telomerase activity of leukemia cells was explored and investigated in the present study. Telomerase activity was measured by the telomerase PCR ELISA assay kit (TRAP); hTERT mRNA expression by reverse transcription polymerase chain reaction (RT-PCR) assay and gel-image system, hTERT protein by immunochemistry and flowcytometry. Results showed Incubation of leukemic cells (HL-60 and K562 cell lines) with 10 mol/l AS PS-ODN would significantly reduce the their mRNA levels and in vitro expression of hTERT protein 24 h later, so that the telomerase activity would be significantly down-regulated or inhibited. In conlusion, the hTERT AS PS-ODN is an excellent inhibitor for telomerase activity.

Introduction: As reported previously, inhibition of telomerase activity with hTERT (human telomerase reverse transcriptase) mRNA AS PS-ODN (Antisense phosphorothioate oligodeoxynucleotide) could increase the effect for CDDP (cis-diamminedichloroplatinum, CDDP) to induce apoptosis of HL-60 and K562 leukemic cells. In these studies, this phenomenon will be further investigated and expanded to leukemia cells from acute and chronic myeloid leukemia (AML and CML). Materials and methods: Cell samples of AML and CML patients, from the first affiliated hospital of Jinan University Medical College, were obtained. The primary cell culture was established to investigate whether or not the inhibition of telomerase activity with hTERT mRNA AS PS-ODN increased the effect for cisplatin to induce apoptosis of leukemic cells from patients. Cell growth was observed with trypan blue dye exclusion. hTERT protein was determined by tissue chemistry and owcytometry. Telomerase activity was tested with the telomerase PCR ELISA assay kit (Boehringer Mannheim). Results: The inhibition of telomerase activity with hTERT mRNA AS PS-ODN could significantly increase the susceptibility of AML or CML cells to CDDP. The apoptotic percentage of cells (AML: 42.68%; CML: 35.72%) treated with AS PS-ODN/CDDP was significantly difierent from that of cells (AML, 29.02%; CML, 23.84%) treated with S PS-ODN/CDDP or CDDP. Conclusion: The inhibition of telomerase activity with hTERT mRNA AS PS-ODN could increase the effect for CDDP to induce apoptosis of leukemic cells from AML and CML patients.

Introduction: We investigated the effect of two antisense oligodeoxynucleotides, previously selected with the help of computer-aided RNA structure prediction, on drug sensitivity, bcl-2 expression and apoptosis of leukemia cells. The drugs tested were etoposide (VP-16), cytarabine (Ara-C), daunorubicin (DNR) and arsenic trioxide (As2O3). Materials and methods: The experimental assays were performed with cultures, IC50 of leukemic cells to drugs, immunochemistry and flow cytometry. Results: The results showed that the two antisense oligodeoxynucleotides significantly reduced IC50 levels for VP-16, Ara-c, DNA and As2O3, inhibited bcl-2 gene expression and induced apoptosis of leukemic cells. Conclusions: Computational prediction of antisense efficacy is faster than other methods and more cost-efficient. This could hasten the development of sequences for both research and clinical applications.