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Zhang Y, Yang X, Zhou H, Yao G, Zhou L, Qian C. BIBR1532 inhibits proliferation and enhances apoptosis in multiple myeloma cells by reducing telomerase activity. PeerJ 2023; 11:e16404. [PMID: 37953768 PMCID: PMC10638922 DOI: 10.7717/peerj.16404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Accepted: 10/13/2023] [Indexed: 11/14/2023] Open
Abstract
Background Multiple myeloma (MM) is a rare haematological disorder with few therapeutic options. BIBR1532, a telomerase inhibitor, is widely used in cancer treatment and has promising outcomes. In this study, we investigated the efficacy and mechanism of action of BIBR1532 in MM. Methods K562 and MEG-01 cells were cultured with BIBR1532 at different concentrations. After 24 and 48 h, cell survival was analyzed. Next, these cells were cultured with 25 and 50 µM BIBR1532 for 48 h, then, cell proliferation, apoptosis, and the expression of the telomerase activity related markers were tested by 5-Ethynyl-2'-deoxyuridine (EdU) staining, flow cytometric analysis, western blot and quantitative real-time PCR (qRT-PCR), respectively. Expression of Bcl-xL, Bad, Survivin, phosphorylation of PI3K, AKT, mTOR, ERK1/2, and MAPK were tested via western blotting. Further experiments were conducted to evaluate the synergistic effects of BIBR1532 and doxorubicin (Dox) or bortezomib (Bor). Results BIBR1532 inhibited K562 and MEG-01 cell survival in a dose- and time-dependent manner. In addition, BIBR1532 hindered cell proliferation while promoting apoptosis, and this effect was enhanced by increasing the BIBR1532 concentration. Moreover, BIBR1532 inhibited TERT and c-MYC expression, PI3K, AKT, mTOR phosphorylation, and facilitated ERK1/2 and MAPK phosphorylation. Additionally, BIBR1532 combined with Dox or Bor showed synergistic effects in MM treatment. Conclusion BIBR1532 inhibits proliferation and promotes apoptosis in MM cells by inhibiting telomerase activity. Additionally, BIBR1532 combined with Dox or Bor exhibited synergistic effects, indicating that BIBR1532 may be a novel medicine for the treatment of MM.
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Affiliation(s)
- Yuefeng Zhang
- Department of Hematology, First People’s Hospital of Linping District, Hangzhou, Zhejiang, China
| | - Xinxin Yang
- Department of Hematology, First People’s Hospital of Linping District, Hangzhou, Zhejiang, China
| | - Hangqun Zhou
- Medical School, Hangzhou Normal University, Hangzhou, Zhejiang, China
| | - Guoli Yao
- Department of Hematology, First People’s Hospital of Linping District, Hangzhou, Zhejiang, China
| | - Li Zhou
- Department of Oncology, First People’s Hospital of Linping District, Hangzhou, Zhejiang, China
| | - Chunyan Qian
- Clinical Laboratory, First People’s Hospital of Linping District, Hangzhou, Zhejiang, China
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Afsar B, Afsar RE. Hypertension and cellular senescence. Biogerontology 2023:10.1007/s10522-023-10031-4. [PMID: 37010665 DOI: 10.1007/s10522-023-10031-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Accepted: 03/21/2023] [Indexed: 04/04/2023]
Abstract
Essential or primary hypertension is a wordwide health problem. Elevated blood pressure (BP) is closely associated not only with increased chronological aging but also with biological aging. There are various common pathways that play a role in cellular aging and BP regulation. These include but not limited to inflammation, oxidative stress, mitochondrial dysfunction, air pollution, decreased klotho activity increased renin angiotensin system activation, gut dysbiosis etc. It has already been shown that some anti-hypertensive drugs have anti-senescent actions and some senolytic drugs have BP lowering effects. In this review, we have summarized the common mechanisms underlying cellular senescence and HT and their relationships. We further reviewed the effect of various antihypertensive medications on cellular senescence and suggest further issues to be studied.
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Affiliation(s)
- Baris Afsar
- Department of Nephrology, School of Medicine, Suleyman Demirel University, Isparta, Turkey.
| | - Rengin Elsurer Afsar
- Department of Nephrology, School of Medicine, Suleyman Demirel University, Isparta, Turkey
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Singh RD, Patel KA, Patel JB, Patel PS. Alterations in p53 Influence hTERT, VEGF and MMPs Expression in Oral Cancer Patients. Asian Pac J Cancer Prev 2022; 23:3141-3149. [PMID: 36172677 PMCID: PMC9810300 DOI: 10.31557/apjcp.2022.23.9.3141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND Mutant p53 is the crucial molecule in the etiopathogenesis of oral cancer. Therefore, we aimed to evaluate the impact of alterations of the p53 gene and its negative feedback regulator, MDM2, on the expression of hTERT, VEGF, and MMPs; the critical genes involved in oral cancer progression. MATERIAL AND METHODS p53 and MDM2 genotyping were done by PCR-RFLP. p53 mutation analysis was performed using PCR-SSCP and sequencing. hTERT, VEGFA isoforms, MMP2, and MMP9 mRNA levels were analyzed by semi-quantitative Reverse Transcriptase PCR. RESULTS Arg allele at p53 exon 4 was significantly associated with overexpression of hTERT, MMP2, and MMP9 individually. Expression of hTERT, VEGF A isoforms, MMP2 and MMP9 were significantly altered in the presence of p53 and MDM2 polymorphisms and p53 mutations in a specific combination. Mutant p53, Arg allele at p53 exon 4 locus, and G/G/or T/T genotype at MDM2revealed increased expression of hTERT, VEGF A isoforms, and MMP2/9. CONCLUSION This study provides evidence that apart from mutant p53, naturally occurring sequence variants in p53codon 72 (Arg72Pro) (rs1042522) and MDM2 (rs2279744) significantly alter the expression of hTERT, VEGF-A isoforms, and MMP2/9 in a specific combination. The differential interaction of codon 72 variants with MDM2, hTERT, VEGF-A isoforms and MMP2/9 play a role in the aggressiveness of oral cancer. The results have important implications for oral cancer progression and should be explored for innovative treatment options.
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Affiliation(s)
- Ragini D Singh
- Department of Biochemistry, All India Institute of Medical Sciences (AIIMS), Rajkot-360110, Gujarat, India. ,For Correspondence:
| | - Kinjal A Patel
- Molecular Oncology Laboratory, Cancer Biology Department, The Gujarat Cancer & Research Institute, Asarwa, Ahmedabad -380 016, Gujarat, India.
| | - Jayendra B Patel
- Molecular Oncology Laboratory, Cancer Biology Department, The Gujarat Cancer & Research Institute, Asarwa, Ahmedabad -380 016, Gujarat, India.
| | - Prabhudas S Patel
- Molecular Oncology Laboratory, Cancer Biology Department, The Gujarat Cancer & Research Institute, Asarwa, Ahmedabad -380 016, Gujarat, India.
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Rafat A, Dizaji Asl K, Mazloumi Z, Movassaghpour AA, Talebi M, Shanehbandi D, Farahzadi R, Nejati B, Nozad Charoudeh H. Telomerase inhibition on acute myeloid leukemia stem cell induced apoptosis with both intrinsic and extrinsic pathways. Life Sci 2022; 295:120402. [PMID: 35176279 DOI: 10.1016/j.lfs.2022.120402] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 02/07/2022] [Accepted: 02/09/2022] [Indexed: 12/24/2022]
Abstract
AIMS Acute Myeloid Leukemia (AML) is an invasive and lethal blood cancer caused by a rare population of Leukemia Stem Cells (LSCs). Telomerase activation is a limitless self-renewal process in LSCs. Apart from telomerase role in telomere lengthening, telomerase (especially hTERT subunit) inhibits intrinsic-, extrinsic-, and p53- mediated apoptosis pathways. In this study, the effect of Telomerase Inhibition (TI) on intrinsic-, extrinsic-, p53-mediated apoptosis, and DNMT3a and TET epigenetic markers in stem (CD34+) and differentiated (CD34-) AML cells is evaluated. MAIN METHODS High-purity CD34+ (primary AML and KG-1a) cells were enriched using the Magnetic-Activated Cell Sorting (MACS) system. CD34+ and CD34- (primary AML and KG-1a) cells were treated with BIBR1532 and then, MTT assay, Annexin V/7AAD, Ki-67 assay, Telomere Length (TL) measurement, and transcriptional alterations of p53, hTERT, TET2, DNMT3a were analyzed. Finally, apoptosis-related genes and proteins were studied. KEY FINDINGS TI with the IC50 values of 83.5, 33.2, 54.3, and 24.6 μM in CD34+ and CD34- (primary AML and KG-1a) cells significantly inhibited cell proliferation and induced apoptosis. However, TI had no significant effect on TL. The results also suggested TI induced intrinsic-, extrinsic-, and p53-mediated apoptosis. It was shown that the expression levels of DNMT3a and TET2 epigenetic markers were highly increased following TI. SIGNIFICANCE In total, it was revealed that TI induced apoptosis through intrinsic, extrinsic, and p53 pathways and increased the expression of DNMT3a and TET2 epigenetic markers.
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Affiliation(s)
- Ali Rafat
- Stem Cell Research Center, Tabriz University of Medical Sciences, Tabriz, Iran; Department of Anatomical Sciences, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran; Student Research Committee, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Khadijeh Dizaji Asl
- Stem Cell Research Center, Tabriz University of Medical Sciences, Tabriz, Iran; Department of Anatomical Sciences, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran; Student Research Committee, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Zeinab Mazloumi
- Stem Cell Research Center, Tabriz University of Medical Sciences, Tabriz, Iran; Student Research Committee, Tabriz University of Medical Sciences, Tabriz, Iran; Department of Applied Cell Sciences, Faculty of Advanced Medical Sciences, Tabriz University of Medical Sciences, Tabriz, Iran
| | | | - Mehdi Talebi
- Department of Applied Sciences, School of Advanced Medical Sciences, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Dariush Shanehbandi
- Immunology research center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Raheleh Farahzadi
- Hematology and Oncology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Babak Nejati
- Hematology and Oncology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
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Liu T, Tian L, Fu X, Wei L, Li J, Wang T. Saffron inhibits the proliferation of hepatocellular carcinoma via inducing cell apoptosis. Panminerva Med 2019; 62:7-12. [PMID: 30657284 DOI: 10.23736/s0031-0808.18.03561-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND Liver cancer remains the third leading cause of cancer-related mortality worldwide. The aim of this study was to explore the effect of saffron on liver cancer cell line QGY-7703 and the underlying molecular mechanism. METHODS Cell growth was detected by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay and cell cycle was assessed by flow cytometry. Besides, cell apoptosis was analyzed by Annexin V/PI (Propidium Iodide) staining, and the senescent cells morphology staining of β-galactosidase was evaluated by microscopy. In addition, ELISA (enzyme-linked immunosorbent assay) Kit was used to assess the activity of telomerase. Moreover, reverse transcription-PCR (polymerase chain reaction) and Western blot analysis was applied to detect mRNA and protein expression levels, respectively. RESULTS Saffron treatment in QGY-7703 cells could significantly inhibit cell growth, arrest cell cycle in the G0/G1 phase, and induce cell apoptosis. Besides, the treatment of saffron could obviously decrease telomerase activity and hTERT level in QGY-7703 cells. In addition, enhanced Bax/Bcl-2 ratio and increased expression of P21 were found in saffron-treated cells. Moreover, we found that the number of senescent cells increased dramatically and the morphology of cells changed obviously after saffron treatment. CONCLUSIONS Saffron administration may provide some experimental evidence for the inhibitory effect of saffron on the proliferation of QGY-7703 cells, suggesting that saffron may have potential utility for the treatment of liver cancer.
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Affiliation(s)
- Tao Liu
- Department of Pharmacy of Traditional Medicine, People's Hospital of Rizhao, Rizhao, China
| | - Li Tian
- Department of Traditional Chinese Medicine, People's Hospital of Rizhao, Rizhao, China
| | - Xuefeng Fu
- Department of Pharmacy, Wulian County Hospital of Traditional Chinese Medicine, Rizhao, China
| | - Lili Wei
- Preventive Vaccination Clinics, the People's Hospital of Zhangqiu Area, Jinan, China
| | - Jing Li
- Department of Surgery, the People's Hospital of Zhangqiu Area, Jinan, China
| | - Tingting Wang
- Department of Traditional Chinese Medicine, People's Hospital of Rizhao, Rizhao, China -
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Lebya K, Garcia‐Smith R, Swaminathan R, Jones A, Russell J, Joste N, Bisoffi M, Trujillo K. Towards a personalized surgical margin for breast conserving surgery—Implications of field cancerization in local recurrence. J Surg Oncol 2017; 115:109-115. [DOI: 10.1002/jso.24469] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 09/19/2016] [Indexed: 01/21/2023]
Affiliation(s)
- Katarina Lebya
- Department of Cell Biology and PhysiologyUniversity of New Mexico Health Sciences CenterAlbuquerqueNew Mexico
| | - Randi Garcia‐Smith
- Department of Cell Biology and PhysiologyUniversity of New Mexico Health Sciences CenterAlbuquerqueNew Mexico
| | | | - Anna Jones
- Department of Internal MedicineUniversity of New Mexico Health Science CenterAlbuquerqueNew Mexico
| | - John Russell
- Department of SurgeryUniversity of New Mexico Health Science CenterAlbuquerqueNew Mexico
| | - Nancy Joste
- Department of PathologyUniversity of New Mexico Health Science CenterAlbuquerqueNew Mexico
| | - Marco Bisoffi
- Biochemistry and Molecular BiologySchmid College of Science and Technology Chapman UniversityOrangeCalifornia
| | - Kristina Trujillo
- Department of Cell Biology and PhysiologyUniversity of New Mexico Health Sciences CenterAlbuquerqueNew Mexico
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7
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Li R, Zhang X, Tian X, Shen C, Zhang Q, Zhang Y, Wang Z, Wang F, Tao Y. Triptolide inhibits tumor growth by induction of cellular senescence. Oncol Rep 2016; 37:442-448. [PMID: 27878302 DOI: 10.3892/or.2016.5258] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Accepted: 10/26/2016] [Indexed: 11/06/2022] Open
Abstract
Cellular senescence, an irreversible growth arrest of cells, is involved in protection against cancer. Triptolide (TPL) plays an important role in immunosuppressive, anti-fertility, anti-cystogenesis and anticancer activities. However, effect and mechanism of TPL on cellular senescence-associated antitumor is rarely reported. Herein HepG2 cells were used to explore the effect of TPL on tumor growth and cellular senescence. We showed that TPL inhibited tumor cell proliferation and growth in vitro and in vivo, accelerated cellular senescence and arrested cells at G0/G1 phase. We further demonstrated that TPL accelerated HepG2 cell senescence by regulating the AKT pathway. In addition, TPL could also enhance cellular senescence and inhibit tumor growth by negatively regulating human telomerase reverse transcriptase (hTERT) signaling pathway. These findings reveal a regulatory mechanism of TPL on cellular senescence, indicating that TPL promotes HepG2 cell senescence through AKT pathway and hTERT pathway simultaneously. Altogether, TPL-induced senescence can be regarded as a promising strategy for anticancer therapy and drug development.
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Affiliation(s)
- Ruidong Li
- Department of General Surgery and Liver Transplant Center, Huashan Hospital, Fudan University, Shanghai 200040, P.R. China
| | - Xiaofei Zhang
- Department of General Surgery and Liver Transplant Center, Huashan Hospital, Fudan University, Shanghai 200040, P.R. China
| | - Xiaoying Tian
- Bioscience Research Center, Shanghai 200120, P.R. China
| | - Conghuan Shen
- Department of General Surgery and Liver Transplant Center, Huashan Hospital, Fudan University, Shanghai 200040, P.R. China
| | - Quanbao Zhang
- Department of General Surgery and Liver Transplant Center, Huashan Hospital, Fudan University, Shanghai 200040, P.R. China
| | - Yihong Zhang
- Bioscience Research Center, Shanghai 200120, P.R. China
| | - Zhengxin Wang
- Department of General Surgery and Liver Transplant Center, Huashan Hospital, Fudan University, Shanghai 200040, P.R. China
| | - Feifei Wang
- Bioscience Research Center, Shanghai 200120, P.R. China
| | - Yifeng Tao
- Department of General Surgery and Liver Transplant Center, Huashan Hospital, Fudan University, Shanghai 200040, P.R. China
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8
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RFPL3 and CBP synergistically upregulate hTERT activity and promote lung cancer growth. Oncotarget 2016; 6:27130-45. [PMID: 26318425 PMCID: PMC4694978 DOI: 10.18632/oncotarget.4825] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2015] [Accepted: 07/30/2015] [Indexed: 12/27/2022] Open
Abstract
hTERT is the key component of telomerase and its overactivation contributes to maintaining telomere length and cell immortalization. Previously, we identified RFPL3 as a new transcription activator of hTERT in lung cancers. However, the exact mechanism of RFPL3 in mediating hTERT activation and its associated signal regulatory network remain unclear. In this study, we found that RFPL3 colocalized and interacted directly with CBP in the nucleus of lung cancer cells. Immunohistochemical analysis of tissue microarrays of lung cancers revealed the simultaneous overexpression of both RFPL3 and CBP predicted relatively poor prognosis. Furthermore, we confirmed their synergistic stimulation on hTERT expression and tumor cell growth. The binding of RFPL3 to hTERT promoter was reduced markedly when CBP was knocked down by its specific siRNA or suppressed by its inhibitor in lung cancer cells with stable overexpression of RFPL3. When one of the two proteins RFPL3 and CBP was upregulated or downregulated, whereas the another remains unchanged, hTERT expression and telomerase activity were activated or repressed accordingly. In the meantime, the growth of lung cancer cells was also promoted or attenuated accordingly. Furthermore, we also found that RFPL3 coordinated with CBP to upregulate hTERT through the CBP-induced acetylation of RFPL3 protein and their co-anchoring at hTERT promoter region. Collectively, our results reveal a new mechanism of hTERT regulation in lung cancer cells and suggest the RFPL3/CBP/hTERT signaling pathway may be a new targets for lung cancer treatment.
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9
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Peek GW, Tollefsbol TO. Down-regulation of hTERT and Cyclin D1 transcription via PI3K/Akt and TGF-β pathways in MCF-7 Cancer cells with PX-866 and Raloxifene. Exp Cell Res 2016; 344:95-102. [PMID: 27017931 DOI: 10.1016/j.yexcr.2016.03.022] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 03/16/2016] [Accepted: 03/22/2016] [Indexed: 11/26/2022]
Abstract
Human telomerase reverse transcriptase (hTERT) is the catalytic and limiting component of telomerase and also a transcription factor. It is critical to the integrity of the ends of linear chromosomes and to the regulation, extent and rate of cell cycle progression in multicellular eukaryotes. The level of hTERT expression is essential to a wide range of bodily functions and to avoidance of disease conditions, such as cancer, that are mediated in part by aberrant level and regulation of cell cycle proliferation. Value of a gene in regulation depends on its ability to both receive input from multiple sources and transmit signals to multiple effectors. The expression of hTERT and the progression of the cell cycle have been shown to be regulated by an extensive network of gene products and signaling pathways, including the PI3K/Akt and TGF-β pathways. The PI3K inhibitor PX-866 and the competitive estrogen receptor ligand raloxifene have been shown to modify progression of those pathways and, in combination, to decrease proliferation of estrogen receptor positive (ER+) MCF-7 breast cancer cells. We found that combinations of modulators of those pathways decreased not only hTERT transcription but also transcription of additional essential cell cycle regulators such as Cyclin D1. By evaluating known expression profile signatures for TGF-β pathway diversions, we confirmed additional genes such as heparin-binding epidermal growth factor-like growth factor (HB EGF) by which those pathways and their perturbations may also modify cell cycle progression.
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Affiliation(s)
- Gregory W Peek
- Department of Biology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Trygve O Tollefsbol
- Department of Biology, University of Alabama at Birmingham, Birmingham, AL, USA; Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, AL, USA; Comprehensive Center for Healthy Aging, University of Alabama at Birmingham, Birmingham, AL, USA; Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL, USA; Nutrition Obesity Research Center, University of Alabama at Birmingham, Birmingham, AL, USA.
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10
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Noureini SK, Wink M. Dose-dependent cytotoxic effects of boldine in HepG-2 cells-telomerase inhibition and apoptosis induction. Molecules 2015; 20:3730-43. [PMID: 25719742 PMCID: PMC6272231 DOI: 10.3390/molecules20033730] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Revised: 02/11/2015] [Accepted: 02/12/2015] [Indexed: 01/14/2023] Open
Abstract
Plant metabolites are valuable sources of novel therapeutic compounds. In an anti-telomerase screening study of plant secondary metabolites, the aporphine alkaloid boldine (1,10-dimethoxy-2,9-dihydroxyaporphine) exhibited a dose and time dependent cytotoxicity against hepatocarcinoma HepG-2 cells. Here we focus on the modes and mechanisms of the growth-limiting effects of this compound. Telomerase activity and expression level of some related genes were estimated by real-time PCR. Modes of cell death also were examined by microscopic inspection, staining methods and by evaluating the expression level of some critically relevant genes. The growth inhibition was correlated with down-regulation of the catalytic subunit of telomerase (hTERT) gene (p < 0.01) and the corresponding reduction of telomerase activity in sub-cytotoxic concentrations of boldine (p < 0.002). However, various modes of cell death were stimulated, depending on the concentration of boldine. Very low concentrations of boldine over a few passages resulted in an accumulation of senescent cells so that HepG-2 cells lost their immortality. Moreover, boldine induced apoptosis concomitantly with increasing the expression of bax/bcl2 (p < 0.02) and p21 (p < 0.01) genes. Boldine might thus be an interesting candidate as a potential natural compound that suppresses telomerase activity in non-toxic concentrations.
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Affiliation(s)
- Sakineh Kazemi Noureini
- Deptartment of Biology, Faculty of Basic Sciences, Hakim Sabzevari University, P.O. Box 397, Sabzevar, 9617966376 Iran.
| | - Michael Wink
- Department of Biology, Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, INF 364, 69120, Heidelberg, Germany.
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Wu XQ, Huang C, He X, Tian YY, Zhou DX, He Y, Liu XH, Li J. Feedback regulation of telomerase reverse transcriptase: new insight into the evolving field of telomerase in cancer. Cell Signal 2013; 25:2462-8. [DOI: 10.1016/j.cellsig.2013.08.009] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Accepted: 08/23/2013] [Indexed: 01/07/2023]
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12
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Shen XH, Xu SJ, Jin CY, Ding F, Zhou YC, Fu GS. Interleukin-8 prevents oxidative stress-induced human endothelial cell senescence via telomerase activation. Int Immunopharmacol 2013; 16:261-7. [DOI: 10.1016/j.intimp.2013.04.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Revised: 03/28/2013] [Accepted: 04/02/2013] [Indexed: 01/17/2023]
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13
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hTERT: Another brick in the wall of cancer cells. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2013; 752:119-128. [DOI: 10.1016/j.mrrev.2012.12.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Revised: 11/28/2012] [Accepted: 12/10/2012] [Indexed: 01/06/2023]
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Chen H, Landen CN, Li Y, Alvarez RD, Tollefsbol TO. Epigallocatechin gallate and sulforaphane combination treatment induce apoptosis in paclitaxel-resistant ovarian cancer cells through hTERT and Bcl-2 down-regulation. Exp Cell Res 2013; 319:697-706. [PMID: 23333498 DOI: 10.1016/j.yexcr.2012.12.026] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Revised: 12/11/2012] [Accepted: 12/20/2012] [Indexed: 12/28/2022]
Abstract
The cellular development of resistance to chemotherapy contributes to the high mortality noted in patients affected by ovarian cancer. Novel compounds that specifically target cellular drug resistance in ovarian cancer are therefore highly desired. Previous epidemiological studies indicate that consumption of green tea and cruciferous vegetables is inversely associated with occurrence of ovarian cancer. Therefore revealing the effects and mechanisms of major components of green tea (epigallocatechin gallate, EGCG) and cruciferous vegetables (sulforaphane, SFN) on ovarian cancer cells will provide necessary knowledge for developing potential novel treatments for the disease. In this study, EGCG or SFN was used to treat both paclitaxel-sensitive (SKOV3-ip1) and -resistant (SKOV3TR-ip2) ovarian cancer cell lines alone or in combination. We found that SFN inhibits cell viability of both ovarian cancer cell lines time- and dose-dependently and that EGCG potentiates the inhibiting effect of SFN on ovarian cancer cells. Cell cycle analysis indicates SFN can arrest ovarian cancer cells in G2/M phase, while EGCG and SFN co-treatment can arrest cells in both G2/M and S phase. Combined EGCG and SFN treatment increases apoptosis significantly in paclitaxel-resistant SKOV3TR-ip2 cells after 6 days of treatment, while reducing the expression of hTERT, the main regulatory subunit of telomerase. Western blotting also indicates that SFN can down-regulate Bcl-2 (a gene involved in anti-apoptosis) protein levels in both cell types. Cleaved poly(ADP-ribose) polymerase (PARP) becomes up-regulated by 6 days of treatment with SFN and this is more pronounced for combination treatment indicating induction of apoptosis. Furthermore, phosphorylated H2AX is up-regulated after 6 days of treatment with SFN alone, and EGCG can potentiate this effect, suggesting that DNA damage is a potential cellular mechanism contributing to the inhibiting effect of EGCG and SFN combination treatment. Taken together, these results indicate that EGCG and SFN combination treatment can induce apoptosis by down-regulating of hTERT and Bcl-2 and promote DNA damage response specifically in paclitaxel-resistant ovarian cancer cell lines and suggest the use of these compounds for overcoming paclitaxel resistance in ovarian cancer treatment.
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Affiliation(s)
- Huaping Chen
- Department of Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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15
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Regulation of the human catalytic subunit of telomerase (hTERT). Gene 2012; 498:135-46. [PMID: 22381618 DOI: 10.1016/j.gene.2012.01.095] [Citation(s) in RCA: 199] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2011] [Revised: 01/29/2012] [Accepted: 01/30/2012] [Indexed: 12/12/2022]
Abstract
Over the past decade, there has been much interest in the regulation of telomerase, the enzyme responsible for maintaining the integrity of chromosomal ends, and its crucial role in cellular immortalization, tumorigenesis, and the progression of cancer. Telomerase activity is characterized by the expression of the telomerase reverse transcriptase (TERT) gene, suggesting that TERT serves as the major limiting agent for telomerase activity. Recent discoveries have led to characterization of various interactants that aid in the regulation of human TERT (hTERT), including numerous transcription factors; further supporting the pivotal role that transcription plays in both the expression and repression of telomerase. Several studies have suggested that epigenetic modulation of the hTERT core promoter region may provide an additional level of regulation. Although these studies have provided essential information on the regulation of hTERT, there has been ambiguity of the role of methylation within the core promoter region and the subsequent binding of various activating and repressive agents. As a result, we found it necessary to consolidate and summarize these recent developments and elucidate these discrepancies. In this review, we focus on the co-regulation of hTERT via transcriptional regulation, the presence or absence of various activators and repressors, as well as the epigenetic pathways of DNA methylation and histone modifications.
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Jiao S, Zheng X, Yang X, Zhang J, Wang L. Losartan inhibits STAT1 activation and protects human glomerular mesangial cells from angiotensin II induced premature senescence. Can J Physiol Pharmacol 2012; 90:89-98. [PMID: 22217266 DOI: 10.1139/y11-105] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Human glomerular mesangial cells (HMCs) have a finite lifespan, and eventually enter irreversible growth arrest known as cellular senescence, which is thought to contribute to kidney ageing and age-related kidney disorders, such as chronic kidney disease. The signal transducer and activator of transcription 1 (STAT1) is a latent transcription factor involved in a variety of signal transduction pathways, including cell proliferation, apoptosis, and differentiation, but whether it could regulate HMC senescence still remains to be explored. In our study, the induction of angiotensin II (Ang II)-accelerated HMC senescence, as judged by increased senescence-associated β-galactosidase (SA-β-gal)-positive staining cells, morphological changes, and G0/G1 cell cycle arrest. STAT1 activity and the expression of p53 and p21Cip1 were increased after Ang II treatment. STAT1 knockdown using RNA interference significantly inhibited the progression of HMC senescence and decreased the elevated expression of p53 and p21Cip1. Pretreating HMCs with Ang II receptor blocker losartan also inhibited the progression of HMC senescence and STAT1 activity. Our results indicate that STAT1 is implicated in the mediation of Ang II-induced HMC senescence through p53/ p21Cip1 pathway, and that losartan could attenuate HMC senescence by regulating STAT1. The antioxidant N-acetyl-L-cysteine reduced ROS production and STAT1 activity induced by Ang II, indicating that Ang II uses ROS as a second messenger to regulate STAT1 activity.
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Affiliation(s)
- Sumin Jiao
- Department of Nephrology, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning 110001, P. R. China
| | - Xiaoyu Zheng
- Department of Nephrology, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning 110001, P. R. China
| | - Xue Yang
- Department of Nephrology, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning 110001, P. R. China
| | - Jin Zhang
- Department of Nephrology, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning 110001, P. R. China
| | - Lining Wang
- Department of Nephrology, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning 110001, P. R. China
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STAT1 mediates cellular senescence induced by angiotensin II and H2O2 in human glomerular mesangial cells. Mol Cell Biochem 2011; 365:9-17. [DOI: 10.1007/s11010-011-1197-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2011] [Accepted: 12/13/2011] [Indexed: 01/22/2023]
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18
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Solorio S, Murillo-Ortíz B, Hernández-González M, Guillén-Contreras J, Arenas-Aranda D, Solorzano-Zepeda FJ, Ruiz-Avila R, Mora-Villalpando C, de la Roca-Chiapas JM, Malacara-Hernández JM. Association between telomere length and C-reactive protein and the development of coronary collateral circulation in patients with coronary artery disease. Angiology 2011; 62:467-72. [PMID: 21441231 DOI: 10.1177/0003319710398007] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Coronary collateral circulation is a stabilizer factor in myocardial ischemia. We attempted to establish a link between collateral circulation, C-reactive protein (CRP), and telomere shortening. PATIENTS AND METHODS A case-control study was performed in patients with (group A) and without (group B) coronary collaterals using coronariography. The patients were males, CRP levels and telomere length in circulating leucocytes were measured; Student t test and logistic regression were used to analyze the data. RESULTS The study included 40 patients aged 53.9 ± 7.0 years (20 per group). Group A exhibited lower CRP levels (2.76 ± 3.34 vs 4.04 ± 3.38; P = .004); whereas telomere length was shorter in group B (2.3 ± 6.9 kb vs 6.1 ± 5.9 kb; P < .0001). CONCLUSIONS Collateral circulation was associated with telomere shortening and elevation of CRP levels.
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Affiliation(s)
- Sergio Solorio
- Unit of Medical Research, UMAE No. 1 Bajio IMSS, Leon, Guanajuato, Mexico.
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19
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The transposon-driven evolutionary origin and basis of histone deacetylase functions and limitations in disease prevention. Clin Epigenetics 2011; 2:97-112. [PMID: 22704332 PMCID: PMC3365375 DOI: 10.1007/s13148-011-0020-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2010] [Accepted: 01/03/2011] [Indexed: 12/19/2022] Open
Abstract
Histone deacetylases (HDACs) are homologous to prokaryotic enzymes that removed acetyl groups from non-histone proteins before the evolution of eukaryotic histones. Enzymes inherited from prokaryotes or from a common ancestor were adapted for histone deacetylation, while useful deacetylation of non-histone proteins was selectively retained. Histone deacetylation served to prevent transcriptions with pathological consequences, including the expression of viral DNA and the deletion or dysregulation of vital genes by random transposon insertions. Viruses are believed to have evolved from transposons, with transposons providing the earliest impetus of HDAC evolution. Because of the wide range of genes potentially affected by transposon insertions, the range of diseases that can be prevented by HDACs is vast and inclusive. Repressive chromatin modifications that may prevent transcription also include methylation of selective lysine residues of histones H3 and H4 and the methylation of selective DNA cytosines following specific histone lysine methylation. Methylation and acetylation of individual histone residues are mutually exclusive. While transposons were sources of disease to be prevented by HDAC evolution, they were also the source of numerous and valuable coding and regulatory sequences recruited by “molecular domestication.” Those sequences contribute to evolved complex transcription regulation in which components with contradictory effects, such as HDACs and HATs, may be coordinated and complementary. Within complex transcription regulation, however, HDACs remain ineffective as defense against some critical infectious and non-infectious diseases because evolutionary compromises have rendered their activity transient.
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Madonna R, De Caterina R, Willerson JT, Geng YJ. Biologic function and clinical potential of telomerase and associated proteins in cardiovascular tissue repair and regeneration. Eur Heart J 2010; 32:1190-6. [PMID: 21148539 DOI: 10.1093/eurheartj/ehq450] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Telomeres comprise long tracts of double-stranded TTAGGG repeats that extend for 9-15 kb in humans. Telomere length is maintained by telomerase, a specialized ribonucleoprotein that prevents the natural ends of linear chromosomes from undergoing inappropriate repair, which could otherwise lead to deleterious chromosomal fusions. During the development of cardiovascular tissues, telomerase activity is strong but diminishes with age in adult hearts. Dysfunction of telomerase is associated with the impairment of tissue repair or regeneration in several pathologic conditions, including heart failure and infarction. Under both physiologic and pathophysiologic conditions, telomerase interacts with promyogenic nuclear transcription factors (e.g. myocardin, serum response factor) to augment the potency of cardiovascular cells during growth, survival, and differentiation. We review recent findings on the biologic function of telomerase and its potential for clinical application in cardiovascular development and repair. Understanding the roles of telomerase and its associated proteins in the functional regulation of cardiovascular cells and their progenitors may lead to new strategies for cardiovascular tissue repair and regeneration.
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Affiliation(s)
- Rosalinda Madonna
- Texas Heart Institute at St. Luke's Episcopal Hospital, Houston, TX, USA
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21
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Shen J, Gammon MD, Wu HC, Terry MB, Wang Q, Bradshaw PT, Teitelbaum SL, Neugut AI, Santella RM. Multiple genetic variants in telomere pathway genes and breast cancer risk. Cancer Epidemiol Biomarkers Prev 2010; 19:219-28. [PMID: 20056641 DOI: 10.1158/1055-9965.epi-09-0771] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
PURPOSE To explore the etiologic role of genetic variants in telomere pathway genes and breast cancer risk. METHODS A population-based case-control study, the Long Island Breast Cancer Study Project, was conducted, and 1,067 cases and 1,110 controls were included in the present study. Fifty-two genetic variants of nine telomere-related genes were genotyped. RESULTS Seven single nucleotide polymorphisms (SNP) showed significant case-control differences at the level of P < 0.05. The top three statistically significant SNPs under a dominant model were TERT-07 (rs2736109), TERT-54 (rs3816659), and POT1-03 (rs33964002). The odds ratios (OR) were 1.56 [95% confidence interval (95% CI), 1.22-1.99] for the TERT-07 G-allele, 1.27 (95% CI, 1.05-1.52) for the TERT-54 T-allele, and 0.79 (95% CI, 0.67-0.95) for the POT1-03 A-allele. TERT-67 (rs2853669) was statistically significant under a recessive model; the OR of the CC genotype was 0.69 (95% CI, 0.69-0.93) compared with the T-allele. However, none of the SNPs retained significance after Bonferroni adjustment for multiple testing at the level of P < 0.001 (0.05/52) except for TERT-07. When restricted to Caucasians (94% of the study subjects), a stronger association for the TERT-07 G-allele was observed with an OR of 1.60 (95% CI, 1.24-2.05; P = 0.0002). No effect modifications were found for variant alleles and menopausal status, telomere length, cigarette smoking, body mass index status, and family history of breast cancer risk. CONCLUSIONS Four SNPs in the TERT and POT1 genes were significantly related with overall breast cancer risk. This initial analysis provides valuable clues for further exploration of the biological role of telomere pathway genes in breast cancer.
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Affiliation(s)
- Jing Shen
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, 630 West 168th Street, P&S 19-418, New York, NY 10032, USA.
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22
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Luo Y, Yi Y, Yao Z. Growth Arrest in Ovarian Cancer Cells by hTERT Inhibition Short-Hairpin RNA Targeting Human Telomerase Reverse Transcriptase Induces Immediate Growth Inhibition but not Necessarily Induces Apoptosis in Ovarian Cancer Cells. Cancer Invest 2009; 27:960-70. [DOI: 10.3109/07357900802491451] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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23
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4-hydroxynonenal, a lipid peroxidation product of dietary polyunsaturated fatty acids, has anticarcinogenic properties in colon carcinoma cell lines through the inhibition of telomerase activity. J Nutr Biochem 2009; 21:818-26. [PMID: 19733043 DOI: 10.1016/j.jnutbio.2009.06.005] [Citation(s) in RCA: 209] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2009] [Revised: 06/08/2009] [Accepted: 06/15/2009] [Indexed: 11/20/2022]
Abstract
The effects of polyunsaturated fatty acids (PUFAs) obtained from the diet on colorectal cancer have been widely explored. However, controversial results have been obtained about the role played by the lipid peroxidation products of PUFAs, such as 4-hydroxy-nonenal (HNE), in the control of colon cancer growth. This aldehyde, indeed, showed both procarcinogenic and protective effects. In an attempt to verify the action of HNE, we studied the effects of a low dose of HNE (1 microM), similar to those "physiologically" found in normal cells and plasma, on telomerase activity, a key parameter of malignant transformation. Caco-2 cells were exposed to HNE and, paralleling cell growth inhibition, we observed the down-regulation of telomerase activity and hTERT expression. Similar effects have also been observed in HT-29 cells, in which HNE inhibited cell proliferation, telomerase activity and hTERT expression, suggesting that the inhibition of telomerase activity could be a general mechanism involved in the antiproliferative effect exerted by this aldehyde. Finally, we elucidated the mechanism of hTERT inhibition by HNE. A reduction of GSH content preceded the decrease of telomerase activity, but this only partially explained the telomerase activity inhibition. The major mechanism of HNE action seems to be the modulation of expression and activity of transcription factors belonging to the Myc/Mad/Max network. Since the presence of PUFAs in the diet exposes epithelial colon cells to HNE, this aldehyde could contribute to cell growth control through the inhibitory action on telomerase activity and hTERT expression, suggesting a protective effect on colon mucosa.
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24
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Neelima PS, Rao Rekha M, Rama S, Rao AJ. Effect of human telomerase reverse transcriptase transfection on differentiation in BeWo choriocarcinoma cells. Reprod Biomed Online 2009; 18:838-49. [PMID: 19490790 DOI: 10.1016/s1472-6483(10)60035-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Arrest of proliferation is one of the prerequisites for differentiation of cytotrophoblasts into syncytiotrophoblasts, and thus during differentiation telomerase activity, as well as human telomerase reverse transcriptase (hTERT) expression, is down-regulated. Considering this, it is of interest to investigate whether syncytium formation can be delayed by prolonging the expression of telomerase in cytotrophoblasts. BeWo cells were transfected with pLPC-hTERT retroviral vector and the reverse transcription-polymerase chain reaction analysis for hTERT mRNA concentrations in the transfected cells revealed a several-fold increase in hTERT mRNA compared with the cells transfected with empty vector, and this confirmed that the transfection was successful. An increase in the proliferation, as assessed by bromodeoxyuridine incorporation assay, as well as an increase in mRNA and protein concentration of various cyclins and proliferating cell nuclear antigen, was noticed. The effect of hTERT transfection was also assessed after the addition of forskolin to induce differentiation and it was observed that cell-cell fusion was delayed and differentiation did not occur in hTERT-transfected cells. However, the effects seen were only transient as stable transfection was not possible and the cells were undergoing apoptosis after 72 h, which suggested that apart from hTERT other factors might be important for immortalization of BeWo cells.
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Affiliation(s)
- P S Neelima
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
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25
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Miri-Moghaddam E, Deezagi A, Soheili ZS. Downregulation of telomerase activity in human promyelocytic cell line using RNA interference. Ann Hematol 2009; 88:1169-76. [PMID: 19415276 DOI: 10.1007/s00277-009-0748-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2008] [Accepted: 04/20/2009] [Indexed: 11/24/2022]
Abstract
Telomerase is a ribonucleoprotein complex. It consists of two main components, human telomerase reverse transcriptase (hTERT) and human telomerase RNA. High telomerase activity is present in most malignant cells, but it is barely detectable in majority of somatic cells. The direct correlation between telomerase reactivation and carcinogens has made hTERT a key target for anticancer therapeutic studies. In this study, for the first time, we evaluated the ability of the new generation of short interfering RNA (siRNA) to regulate telomerase activity in the human promyelocytic leukemia cell line (HL-60). Transient transfection cell line by hTERT siRNAs resulted in statistically significant suppression of hTERT messenger RNAs which were detected by quantitative real-time polymerase chain reaction, while the expressed hTERT protein levels were measured by flow cytometry. The results of telomeric repeat amplification protocol showed that telomerase activity was significantly reduced upon transfection of the HL-60 cell line with hTERT siRNAs. The results of this study showed that telomerase activity and cell proliferation were efficiently inhibited in the hTERT siRNA-treated leukemic cell line.
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Affiliation(s)
- E Miri-Moghaddam
- National Institute of Genetic Engineering and Biotechnology (NIGEB), Tehran, Iran
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26
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Folini M, Pennati M, Zaffaroni N. RNA interference-mediated validation of genes involved in telomere maintenance and evasion of apoptosis as cancer therapeutic targets. Methods Mol Biol 2009; 487:303-30. [PMID: 19301654 DOI: 10.1007/978-1-60327-547-7_15] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The discovery of new cancer-related therapeutic targets is mainly based on the identification of genes involved in pathways selectively exploited in cancer cells, including those leading to unlimited replicative potential, evasion of apoptosis, angiogenesis, tissue invasion and metastatic spread. Potentially, a gene--or a gene product--is recognized as a cancer target whether its modulation in experimental models can specifically modify or revert the cancer phenotype. As soon as RNA interference (RNAi)--a natural gene silencing mechanism--was demonstrated in mammalian cells, it rapidly became an essential means for gene knockdown in preclinical models, making it possible to define the role of several human genes and to identify those specifically involved in the onset and progression of cancer. Owing to its powerful gene-silencing properties, RNAi has been proposed as a useful tool to validate new therapeutic targets and to develop innovative anticancer therapies. This chapter summarizes the findings from recent studies relying on the use of RNAi-based approaches to functionally validate therapeutic targets related to two tumor hallmarks: the unlimited replicative potential (i.e., activation of telomere maintenance mechanisms) and evasion of apoptosis (i.e., up-regulation of anti-apoptotic factors).
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Affiliation(s)
- Marco Folini
- Dipartimento di Oncologia Sperimentale e Laboratori, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy
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27
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Abstract
Telomerase has fundamental roles in bypassing cellular aging and in cancer progression by maintaining telomere homeostasis and integrity. However, recent studies have led some investigators to suggest novel biochemical properties of telomerase in several essential cell signaling pathways without apparent involvement of its well established function in telomere maintenance. These observations may further enhance our understanding of the molecular actions of telomerase in aging and cancer. This review will provide an update on the extracurricular activities of telomerase in apoptosis, DNA repair, stem cell function, and in the regulation of gene expression.
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28
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Yang C, Przyborski S, Cooke MJ, Zhang X, Stewart R, Anyfantis G, Atkinson SP, Saretzki G, Armstrong L, Lako M. A key role for telomerase reverse transcriptase unit in modulating human embryonic stem cell proliferation, cell cycle dynamics, and in vitro differentiation. Stem Cells 2008; 26:850-63. [PMID: 18203676 DOI: 10.1634/stemcells.2007-0677] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Embryonic stem cells (ESC) are a unique cell population with the ability to self-renew and differentiate into all three germ layers. Human ESC express the telomerase reverse transcriptase (TERT) gene and the telomerase RNA (TR) and show telomerase activity, but TERT, TR, and telomerase are all downregulated during the differentiation process. To examine the role of telomerase in human ESC self-renewal and differentiation, we modulated the expression of TERT. Upregulation of TERT and increased telomerase activity enhanced the proliferation and colony-forming ability of human ESC, as well as increasing the S phase of the cell cycle at the expense of a reduced G1 phase. Upregulation of TERT expression was associated with increases in CYCLIN D1 and CDC6 expression, as well as hyperphosphorylation of RB. The differentiated progeny of control ESC showed shortening of telomeric DNA as a result of loss of telomerase activity. In contrast, the differentiated cells from TERT-overexpressing ESC maintained high telomerase activity and accumulated lower concentrations of peroxides than wild-type cells, implying greater resistance to oxidative stress. Although the TERT-overexpressing human ESC are able to form teratoma composed of three germ layers in vivo, their in vitro differentiation to all primitive and embryonic lineages was suppressed. In contrast, downregulation of TERT resulted in reduced ESC proliferation, increased G1, and reduced S phase. Most importantly, downregulation of TERT caused loss of pluripotency and human ESC differentiation to extraembryonic and embryonic lineages. Our results indicate for the first time an important role for TERT in the maintenance of human ESC pluripotency, cell cycle regulation, and in vitro differentiation capacity.
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Affiliation(s)
- Chunbo Yang
- North East Institute for Stem Cell Research, Newcastle upon Tyne NE1 3BZ, United Kingdom
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29
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Tárkányi I, Aradi J. Pharmacological intervention strategies for affecting telomerase activity: future prospects to treat cancer and degenerative disease. Biochimie 2007; 90:156-72. [PMID: 17945408 DOI: 10.1016/j.biochi.2007.09.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2007] [Accepted: 09/04/2007] [Indexed: 12/20/2022]
Abstract
Telomerase enzyme is a ribonucleoprotein maintaining the length of the telomeres by adding G-rich repeats to the end of the eukaryotic chromosomes. Normal human somatic cells, cultured in vitro, have a strictly limited proliferative potential undergoing senescence after about 50-70 population doublings. In contrast, most of the tumor cells have unlimited replicative potential. Although the mechanisms of immortalization are not understood completely at a genetic level, the key role of the telomere/telomerase system in the process is clear. The DNA replication machinery is not able to replicate fully the DNA at the very end of the chromosomes; therefore, about 50-200 nucleotides are lost during each of the replication cycles resulting in a gradual decrease of telomere length. Critically short telomere induces senescence, subsequent crisis and cell death. In tumor cells, however, the telomerase enzyme prevents the formation of critically short telomeres, adding GGTTAG repeats to the 3' end of the chromosomes immortalizing the cells. Immortality is one of the hallmarks of cancer. Besides the catalytic activity dependent telomere maintenance, catalytic activity-independent effects of telomerase may also be involved in the regulation of cell cycle. The telomere/telomerase system offers two possibilities to intervene the proliferative activity of the cell: (1) inhibition the telomere maintenance by inhibiting the telomerase activity; (2) activating the residual telomerase enzyme or inducing telomerase expression. Whilst the former approach could abolish the limitless replicative potential of malignant cells, the activation of telomerase might be utilized for treating degenerative diseases. Here, we review the current status of telomerase therapeutics, summarizing the activities of those pharmacological agents which either inhibit or activate the enzyme. We also discuss the future opportunities and challenges of research on pharmacological intervention of telomerase activity.
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Affiliation(s)
- I Tárkányi
- 3rd Department of Internal Medicine, University of Debrecen, 22 Moricz Zsigmond Krt., Debrecen 4004, Hungary
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30
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Affiliation(s)
- Jean-Louis Mergny
- INSERM, U565, Acides Nucléiques: Dynamique, Ciblage et Fonctions Biologiques, 43 Rue Cuvier, CP26, Paris Cedex 05, 75231, France.
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De Cian A, Lacroix L, Douarre C, Temime-Smaali N, Trentesaux C, Riou JF, Mergny JL. Targeting telomeres and telomerase. Biochimie 2007; 90:131-55. [PMID: 17822826 DOI: 10.1016/j.biochi.2007.07.011] [Citation(s) in RCA: 477] [Impact Index Per Article: 28.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2007] [Accepted: 07/16/2007] [Indexed: 01/06/2023]
Abstract
Telomeres and telomerase represent, at least in theory, an extremely attractive target for cancer therapy. The objective of this review is to present the latest view on the mechanism(s) of action of telomerase inhibitors, with an emphasis on a specific class of telomere ligands called G-quadruplex ligands, and to discuss their potential use in oncology.
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Affiliation(s)
- Anne De Cian
- INSERM, U565, Acides nucléiques: dynamique, ciblage et fonctions biologiques, 43 rue Cuvier, CP26, Paris Cedex 05, F-75231, France
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