The pro-apoptotic effect of novel pyrazolo[4,3-e]tetrazolo[4,5-b][1,2,4]triazine derivatives in HT-29 colon cancer cells

Colon cancer has been is considered as the major cause of death in many countries in the world. The currently used therapy is cytotoxic and as a search for novel anti-cancer drug candidates among [1,2,4]triazine derivatives is a promising field of research. The diverse biological activities of [1,2,4]triazine: antiviral, antitumor, antifungal, anti-inflammatory and hypotensive has been reported. In addition numerous studies showed that [1,2,4]triazine condensed with other heterocycles possesses a broad spectrum of biological activities. The structure of tricyclic pyrazolo[4,3-e]tetrazolo[4,5-b][1,2,4]triazine derivatives is similar to CDK inhibitors which play crucial role in treatment of cancer. Hence we designed a novel series of pyrazolo[4,3-e]tetrazolo[4,5-b][1,2,4]triazine derivatives that might have a potential anticancer effect in colon adenocarcinoma cells. Cytotoxic activity of novel pyrazolo[4,3-e]tetrazolo[4,5-b][1,2,4]triazine derivatives was evaluated against HT-29 – colon adenocarcinoma cell line. Cell viability was assessed according to the Carmichael's method using tetrazolium salt after 24 hours of incubation. The induction of apoptosis was determined using annexin V and propidium iodide. The decrease of mitochondrial potential was measured using JC-1 MitoScreen kit. We showed that the tested compounds led to the inhibition of cell viability. Furthermore novel synthesized derivatives had a significant cytotoxic activity in HT-29 cells comparable to roscovitine and 5-flurouracil. Moreover pyrazolo[4,3-e]tetrazolo[4,5-b][1,2,4]triazine derivatives led to the decrease of mitochondrial potential in tested cell line. Further studies will be required to understand the detailed molecular mechanism of action of novel series of pyrazolo[4,3-e]tetrazolo[4,5-b][1,2,4]triazine. (author)