Tomentosin Induces Telomere Shortening and Caspase-Dependant Apoptosis in Cervical Cancer Cells
Nawel Merghoub1,2,3,4, Hassan El Btaouri3, Laila Benbacer2
1Laboratoire de Biochimie-Immunologie, Faculté des Sciences de Rabat, Agdal, Morocco.
Abstract:
Tomentosin, a natural sesquiterpene lactone purified from of Inula viscosa L., was investigated for its anti-proliferative, telomere shortening, and apoptotic effects on human cervical cancer HeLa and SiHa cell lines. Tomentosin was found to inhibit the growth of SiHa and HeLa cell lines in dose and time-dependent manner (IC50 values of 7.10 ± 0.78 μM and 5.87 ± 0.36 μM, respectively after 96 h of treatment). As evidenced by TTAGGG telomere length assay, tomentosin target specifically the telomeric overhang lengthening. This was confirmed by the evaluation of the cytotoxic effects of tomentosin in the foetal fibroblast Wi38 and JW10 cells which were derived from Wi38 and express hTERT, the telomerase catalytic subunit. We found that JW10 cells are 4.7-fold more sensitive to tomentosin which argues for telomere as its specific target. Furthermore, we found that tomentosin mediate this cytotoxic effect by inducing apoptosis and cell cycle arrest at G2/M phase. Morphological features of treated cells, as evidenced by Hoechst 33324 staining, revealed that the cytotoxic effect was due to induction of apoptosis. This was accompanied by pro-caspase-3 cleavage, an increase in caspase-3 activity and a cleavage of poly (ADP-ribose) polymerase (PARP). Moreover, tomentosin induced a decrease in mitochondrial membrane potential (ΔΨm) and an increase in reactive oxygen species (ROS), accompanied by a decrease in Bcl-2 expression. This indicates that tomentosin-induced apoptosis may involve a mitochondria-mediated signaling pathway. This study provides the first evidence that tomentosin targets telomere machinery and induces apoptosis in cervical cancer cells. The molecular mechanism underlying tomentosin-induced apoptosis may involve a mitochondria-mediated signaling pathway. J. Cell. Biochem. 118: 1689-1698, 2017. © 2016 Wiley Periodicals, Inc.
Insights
Tomentosin, a natural compound, inhibits human cervical cancer cell growth by targeting telomeres and inducing apoptosis. This sesquiterpene lactone shows promise as a novel anti-cancer therapeutic agent.
Area of Science:
- Natural Product Chemistry
- Cancer Biology
- Molecular Pharmacology
Background:
- Cervical cancer remains a significant global health challenge, necessitating novel therapeutic strategies.
- Sesquiterpene lactones, like tomentosin from Inula viscosa L., are plant-derived compounds with potential anti-cancer properties.
- Understanding the molecular mechanisms of natural compounds is crucial for drug development.
Purpose of the Study:
- To investigate the anti-proliferative, telomere-shortening, and apoptotic effects of tomentosin on human cervical cancer cell lines (HeLa and SiHa).
- To elucidate the specific molecular targets and pathways involved in tomentosin's anti-cancer activity.
- To evaluate tomentosin's potential as a therapeutic agent for cervical cancer.
Main Methods:
- Cell viability assays (IC50 determination) were performed on HeLa and SiHa cells.
- Telomere length was assessed using the TTAGGG telomere length assay.
- Apoptosis was evaluated through morphological analysis (Hoechst 33324 staining), caspase-3 activity, PARP cleavage, mitochondrial membrane potential (ΔΨm), reactive oxygen species (ROS) production, and Bcl-2 expression.
Main Results:
- Tomentosin exhibited dose- and time-dependent inhibition of HeLa and SiHa cell growth (IC50 values: 5.87 ± 0.36 μM and 7.10 ± 0.78 μM, respectively).
- Tomentosin specifically targeted telomeric overhang lengthening, as evidenced by increased sensitivity in telomerase-expressing JW10 cells compared to Wi38 cells.
- Tomentosin induced apoptosis via a mitochondria-mediated pathway, characterized by G2/M cell cycle arrest, caspase-3 activation, PARP cleavage, decreased ΔΨm, increased ROS, and reduced Bcl-2 expression.
Conclusions:
- Tomentosin effectively inhibits cervical cancer cell proliferation and induces apoptosis, targeting the telomere machinery.
- The observed anti-cancer effects are mediated through a mitochondria-dependent signaling pathway.
- Tomentosin represents a promising natural compound for the development of novel cervical cancer therapies.
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