We aim to determine the regulation of apoptosis by paclitaxel-induced and understand cancer dynamics to treatment targets for HeLa cells by identifying decrease/increase genes expression on HeLa cells. In this study, the anti-tumor effects of Paclitaxel (PAC) on HeLa cells have been studied in order to determine the cellular and molecular mechanisms of these effects. PAC has been applied to HeLa cells in 6 different doses (3, 7.5, 15, 30, 60, 120 nM) for 48 hours and the IC50 dose MTT method, has been determined with apoptic index (AI) DAPI. Morphological aspects have been demonstrated using light, phase contrast and fluorescent microscopes, additionally activation of Caspase 3,7 and 10 have been shown using florescent spectroscopy. RT-PCR and qRT-PCR have been used to evaluate pro/anti-apoptotic gene expression. According to the parameters being evaluated; PAC has reduced cell multiplication based on dosage and time (p<0.01). 15 nM has been determined as the IC50 value. AI value has been determined as 42%. In the molecular level analyses in addition to the increase in Caspase3,7,10 activation, RT-PCR results show that bax, bak, bcl-x, bik, mcl-1 genes are expressed in the control group as well as the experimental 15 nM group; whereas bak, bcl-x ve bik genes have a decrease in expression compared to the control group. qRT-PCR results show that Apaf1, Bad, Bax, Bcl2L11, Caspase1, Caspase10, Caspase4, Caspase7, Dffa, Fas, Htra2, Lrdd, NFKB1, NFKB2, PMAIP1, RELA, RELB, TNFRSF10A, TNFRSF10C, TNFRSF10D, TNFRSF1A, TNFRSF21, TNFRSF25 gene expressions have increased significantly. On the other hand, BAG1, BBC3, Bcl2L1, Bcl2L10, Bid, Caspase2, Caspase6, Caspase8, Caspase9, FADD, FAM96A, FasLG, HRK, SOCS3, TNF, TNFSF10, TRAF5, TRAF6 mRNA levels are significantly decreased.

Nowadays increasing effectiveness in cancer therapy and investigation of formation of new strategies that enhance antiproliferative activity against target organs has become a subject of interest. Although the molecular mechanisms of apoptosis can not be fully explained, it is known that cell suicide program existing in their memory genetically is activated by pathophysiological conditions and events such as oxidative stress. Low pressure (hypobaric) conditions that create hypoxia promote apoptosis by inhibiting cell cycling. In this study, determination of the effects of fractional hypobaric applications at different times on HeLa cells at cellular and molecular levels were targeted. Experiments were carried out under hypobaric conditions (35.2 kPa) in a specially designed hypobaric cabin including 2% O 2 and 98% N. Application of fractional hypobaric conditions was repeated two times for 3 hours with an interval of 24 hours. At the end of the implementation period cells were allowed to incubate for 24 hours for activation of repair mechanisms. Cell kinetic parameters such as growth rate (MTT) and apoptotic index were used in determination of the effect of hypobaric conditions on HeLa cells. Also in our study expression levels of the Bcl-2 gene family that have regulatory roles in apoptosis were determined by the RT-PCR technique to evaluate molecular mechanisms. The results showed that antiproliferative effect of hypobaric conditions on HeLa cells started three hours from the time of application and increased depending on the period of exposure. While there was a significant decrease in growth rate values, there was a significant increase in apoptotic index values (p<0.01). Also molecular studies showed that hypobaric conditions caused a significant increase in expression level of proapoptotic gene Bax and significant decrease in antiapoptotic Bfl-1. Consequently fractional application of hypobaric conditions on HeLa cell cultures increased both antiproliferative and apoptotic effects and these effects were triggered by the Bax gene.