Tomentosin Induces Telomere Shortening and Caspase-Dependant Apoptosis in Cervical Cancer Cells.

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.

Retama monosperma n-hexane extract induces cell cycle arrest and extrinsic pathway-dependent apoptosis in Jurkat cells.

BACKGROUND: Retama monosperma L. (Boiss.) or Genista monosperma L. (Lam.), locally named as "R'tam", is an annual and spontaneous plant belonging to the Fabaceae family. In Morocco, Retama genus is located in desert regions and across the Middle Atlas and it has been widely used in traditional medicine in many countries. In this study, we show that Retama monosperma hexane extract presents significant anti-leukemic effects against human Jurkat cells. METHODS: Human Jurkat cells, together with other cell lines were screened with different concentrations of Retama monosperma hexane extract at different time intervals. Growth inhibition was determined using luminescent-based viability assays. Cell cycle arrest and apoptosis were measured by flow cytometry analysis. Combined caspase 3 and 7 activities were measured using luminometric caspase assays and immunoblots were performed to analyze expression of relevant pro- and anti-apoptotic proteins. GC-MS were used to determine the chemical constituents of the active extract. RESULTS: Retama monosperma hexane extract (Rm-HE) showed significant cytotoxicity against Jurkat cells, whereas it proved to be essentially ineffective against both normal mouse fibroblasts (NIH3T3) and normal lymphocytes (TK-6). Cytometric analysis indicated that Rm-HE promoted cell cycle arrest and apoptosis induction accompanied by DNA damage induction indicated by an increase in p-H2A.X levels. Rm-HE induced apoptosis was partially JNK-dependent and characterized by an increase in Fas-L levels together with activation of caspases 8, 3, 7 and 9, whereas neither the pro-apoptotic nor anti-apoptotic mitochondrial membrane proteins analyzed were significantly altered. Chemical identification analysis indicated that α-linolenic acid, campesterol, stigmasterol and sitosterol were the major bioactive components within the extract. CONCLUSIONS: Our data suggest that bioactive compounds present in Rm-HE show significant anti leukemic activity inducing cell cycle arrest and cell death that operates, at least partially, through the extrinsic apoptosis pathway.

INDUCTION OF CELL CYCLE ARREST AND APOPTOSIS BY ORMENIS ERIOLEPIS A MORROCAN ENDEMIC PLANT IN VARIOUS HUMAN CANCER CELL LINES.

BACKGROUND: Ormenis eriolepis Coss (Asteraceae) is an endemic Moroccan subspecies, traditionally named "Hellala" or "Fergoga". It's usually used for its hypoglycemic effect as well as for the treatment of stomacal pain. As far as we know, there is no scientific exploration of anti tumoral activity of Ormenis eriolepis extracts. MATERIALS AND METHODS: In this regard, we performed a screening of organic extracts and fractions in a panel of both hematological and solid cancer cell lines, to evaluate the potential in vitro anti tumoral activity and to elucidate the respective mechanisms that may be responsible for growth arrest and cell death induction. The plant was extracted using organic solvents, and four different extracts were screened on Jurkat, Jeko-1, TK-6, LN229, SW620, U2OS, PC-3 and NIH3T3 cells. RESULTS: Cell viability assays revealed that, the IC50 values were (11,63±5,37µg/ml) for Jurkat, (13,33±1,67µg/ml) for Jeko-1, (41,67±1,98µg/ml) for LN229 and (19,31±4,88µg/ml) for PC-3 cells upon treatment with Oe-DF and Oe-HE respectively. Both the fraction and extract exhibited no effects on TK6 and NIH3T3. Cytometry analysis accompanied by DNA damage signaling protein levels monitoring (p-H2A.X), showed that both the Dichloromethane Fraction and Hexanic extract induce DNA double stranded breaks (DSBs) accompanied by cell cycle arrest in G1 (Jurkat, Jeko -1 and LN22) and G2/M (PC-3) phases which is agreed with the caspase activity observed. Additional experiments with selective inhibitors of stress and survival pathways (JNK, MAPK, Rho, p53, and JAK3) indicated that none of these pathways was significantly involved in apoptosis induction. The bioactive compound analysis by CG/MS indicated that the major compounds in Oe-DF were: Linoleic Acid (15,89%), Podophyllotoxin (17,89%) and Quercetin (22,95%). For Oe-HE the major molecules were: Linoleic Acid (9,76%), α-curcumene (7,07%), α-bisabolol (5,49%), Campesterol (4,41%), Stigmasterol (14,08%) and ß-sitosterol (7,49%). CONCLUSION: Our data suggest that bioactive compounds present in Ormenis eriolepis show significant anti proliferative activity inducing cell cycle arrest and cell death operating through apoptosis pathway.