We detected early and late nevertheless apoptosis because in the first steps apoptosis can be reversible. The UV light microscopy test allowed us to appreciate a definitive sta tus. The Inhibitors,Modulators,Libraries observation that non tumorigenic HaCaT cells are less sensitive to different treatments is probably due to the fact that the rate of multiplication and metabo lism is slower in HaCaT cells than in tumor cells. These results are in agreement with other published data reporting that PTX sensitizes in vivo and in vitro cancer cells to chemotherapy, particularly to adriamycin. Within this context, we previously reported that the PTX is able to sensitize lymphoma and leukemic cancer cells to apoptosis by adriamycin or perillyl alcohol. Similar results have been reported with radiotherapy.

The observations of the present work are in agree ment with recent data in which our group demonstrated that PTX increases apoptosis and inhibits senescence in HeLa and SiHa Cells treated with adriamycin, an anthra cycline used also Inhibitors,Modulators,Libraries against cervical Inhibitors,Modulators,Libraries cancer. The present results are important because CIS is the first drug of elec tion in the treatment of cervical cancer. Additionally to published data, the results of the present work strongly suggest that the cytotoxicity of PTX is not Inhibitors,Modulators,Libraries limited to one type of tumor cells or to chemotherapeutic drugs, incre menting its potential utilization in Oncology. The low toxicity showed by CIS in survival test may be explained because CIS induces senescence. Senescence originally was considered to be a tumor sup pressor mechanism.

However its role in Oncol ogy is not clear because senescent cells though they cannot replicate, continue releasing growth factors, enzymes and other products that under certain condi tions promote tumor growth. It is very interesting that PTX does not induce senescence, and strongly decreases the senescence induced by CIS. The impor tance of these observations is Inhibitors,Modulators,Libraries that an antitumoral treat ment that induces principally apoptosis rather than senescence is preferable in cancer cells. Different mechanisms can explain our observations. PTX also has antimetastatic activity and arrests the cell cycle in the G2M, in which the tumors are more sensitive to the toxic effects of some chemotherapeutic and radiotherapeutic agents. PTX has been linked as well to the activation of caspase.

In this study, an important activity of caspase was detected in HeLa and SiHa cells treated with PTX or PTX CIS and, in minor degree, with CIS. In addition, this caspase activity is directly proportional to the level of apoptosis confirming selleck chemicals Rucaparib its participation. In SiHa cells treated with CIS alone, we observed low cas pase activity. In this regard, it has been reported that CIS may also exert its apoptotic activity by caspase independent pathways. PTX is a strong inhibitor of phosphodiesterase activ ity.