Pyridostatin is a synthetic small-molecule stabilizer of G-quadruplexe . G-quadruplexe is a kind of secondary structure of DNA that usually exists in the end of the chromosome or the telomeres. Since G-quadruplexe is also enriched in the promoters of a serious of proto-oncogenes including c-kit, K-ras and Bcl-2, they are thought to participate in the regulation of gene replication and transcription. Besides that, G-quadruplexe has been found to affect the elongation, replication and capping of telomeres. Based on these findings, a lot of small molecules that can interact with G-quadruplexe have been designed and synthesized to help demonstrate the existence and roles of G-quadruplexe or to be developed as selective anti-cancer drugs. It has been reported that some small molecules interacting with G-quadruplexe can cause the progressive shortening of telomeres and subsequently the active the DNA damage response resulting in cell cycle arrest. Among these molecules, pyridostatin is a synthetic small-molecule stabilizer of G-quadruplexe with the ability to adapt the dynamic and diverse structures of G-quadruplex. Pyridostatin competed for binding with the telomere associated proteins and induced the dysfunction of telomeres. In the FRET melting assay using human telomeric G-quadruplex-forming sequence and ds-DNA, pyridostatin showed maximal stabilization effect of the G-quadruplex sequence at concentration of 1 μM while showed no effect on the ds-DNA. In a panel of three cancer cell lines (HeLa, U2OS and HT1080) and a normal cell line (WI-38), treatment of pyridostatin significantly inhibited cell growth with IC50 values of 0.89 to 10 μM after 72 hours. The selectivity of pyridostatin against HT1080 cells was 18-fold higher than that against the normal cells .