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Effects of hypobaric conditions on apoptosis signalling pathways in HeLa cells
Gul Ozcan Arican1, Walid Khalilia, Ugur Serbes
1Department of Biology, Faculty of Science, Istanbul University, Istanbul, Turkey
Abstract:
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% O2 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.
Insights
Fractional hypobaric conditions, mimicking hypoxia, effectively inhibit HeLa cancer cell growth and promote apoptosis. This strategy increases the pro-apoptotic Bax gene and decreases the anti-apoptotic Bfl-1 gene, offering a novel cancer therapy approach.
Area of Science:
- Oncology
- Cell Biology
- Hypoxia Research
Background:
- Cancer therapy seeks novel strategies to enhance antiproliferative activity.
- Apoptosis, a genetically programmed cell suicide, is crucial in cancer treatment and can be triggered by conditions like hypoxia.
- Hypobaric (low pressure) conditions induce hypoxia, which is known to promote apoptosis by inhibiting cell cycling.
Purpose of the Study:
- To investigate the cellular and molecular effects of fractional hypobaric applications on HeLa cells.
- To determine the impact of varying exposure times to hypobaric conditions on cancer cell kinetics and apoptosis.
- To elucidate the molecular mechanisms underlying hypobaric-induced apoptosis in cancer cells.
Main Methods:
- HeLa cells were exposed to fractional hypobaric conditions (35.2 kPa, 2% O2) twice for 3 hours with a 24-hour interval.
- Cell growth rate was assessed using MTT assays, and the apoptotic index was determined.
- Gene expression levels of the Bcl-2 family, including Bax and Bfl-1, were analyzed using RT-PCR.
Main Results:
- Hypobaric conditions demonstrated an antiproliferative effect on HeLa cells, commencing within 3 hours and intensifying with exposure duration.
- A significant decrease in cell growth rate and a significant increase in the apoptotic index were observed (p<0.01).
- Molecular analysis revealed a significant upregulation of the pro-apoptotic gene Bax and a significant downregulation of the anti-apoptotic gene Bfl-1.
Conclusions:
- Fractional hypobaric applications effectively enhance both antiproliferative and apoptotic effects in HeLa cancer cells.
- The observed effects are molecularly triggered by the modulation of key apoptosis-regulating genes, specifically the Bax gene.
- This study suggests hypobaric conditions as a promising strategy for developing novel cancer therapies.
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