Phosphorothioate-modified antisense oligonucleotides against human telomerase reverse transcriptase sensitize cancer cells to radiotherapy

Emergence of resistance, unavoidable systemic toxicity and unsatisfactory efficacy arethe main obstacles for traditional cancer therapy. Combination with phosphorothioate modified antisense oligonucleotides (PS‑ASODN) against human telomerase reverse transcriptase (hTERT) may enhance the therapeutic effect of irradiation. However, the effect of PS‑ASODN against hTERT on the anti‑tumor effects of irradiation in liver cancer remain unclear. In the current study, Walker 256 cells were transfected with hTERT PS‑ASODN. Cell proliferation and cell viability were measured using the MTT assay and cell senescence was examined by SA‑β‑gal staining. Telomerase activity was determined by telomeric repeat amplification protocol‑polymerase chain reaction‑ELISA. Cell apoptosis was assayed by flow cytometry and DNA damage was determined by the comet assay.The PS‑ASODN was demonstrated to have an inhibitory effect on cell proliferation and accelerated effect on cell senescence by inhibiting telomerase activity. PS‑ASODN promoted the irradiation‑induced inhibition of cell viability and telomerase activity, and irradiation‑induced DNA damage and cell apoptosis via the activation of apoptosis‑associated proteins. Taken together, these results indicated that combined treatment of PS‑ASODN with irradiation significantly enhanced tumor inhibition. Therefore, PS‑ASODN provides an experimental foundation for gene therapy and is proposed for application in clinical treatment of liver cancer combined with radiotherapy.