OBJECTIVETo explore the anti-cancer effects of siRNAs targeting hTERT in SMMC-7721 cells.

METHODSTwo siRNAs targeting hTERT mRNA were designed and synthesized by T7 transcription system in vitro. MMT, RT-PCR and Western blot were applied to evaluate effects on inhibiting cell growth, hTERT mRNA and protein expression in SMMC-7721 cells.

RESULTSsiRNAs decreased cell proliferation in a dose-dependent manner. At a concentration of 100 nmol/L, siRNAs exhibited obvious effects on inhibiting hTERT mRNA and protein expression in SMMC-7721 cells.

CONCLUSIONsiRNAs targeting hTERT have significant inhibitory effects on hTERT gene expression in SMMC-7721 cells. siRNA has the possibility to become a new anti-cancer agent

DNA-Binding Proteins ; antagonists & inhibitors ; genetics ; Gene Targeting ; Genetic Therapy ; Humans ; Liver Neoplasms ; pathology ; therapy ; RNA, Small Interfering ; genetics ; Telomerase ; antagonists & inhibitors ; genetics

OBJECTIVESTo study the inhibitory effects of mouse telomerase RNA (mTR) antisense oligodeoxynucleotide(ASODN) on telomerase activity in rat spermatogonia.

METHODS9-mer phosphorothioate mTR-ASODN was encapsulated by Lipofect AMINE 2000 (LF 2000) and transfected to type A spermatogonia in Snrague Dawley (SD) rat. Telomerase activity was detected by aid of TRAP-SYBR-Green staining and Bioluminescence technique in type A spermatogonia treated or untreated with ASODN.

RESULTSmTR-ASODN conjugated with LF 2000 could significantly inhibit telomerase activity of spermatogonia(P < 0.01). mTR mRNA level also decreased while the spermatogonia were treated with ASODN for 24 h. No change of telomerase activity and apoptosis were observed when SODN, RODN or single LF 2000 was used.

CONCLUSIONSAntisense oligodeoxynucleotide of mTR conjugated with LF 2000 could significantly inhibit telomerase activity of spermatogonia. mTR-ASODN might inhibit telomerase activity of spermatogonia at transcription level.

Animals ; Male ; Oligodeoxyribonucleotides, Antisense ; pharmacology ; RNA ; antagonists & inhibitors ; genetics ; metabolism ; RNA, Messenger ; analysis ; Rats ; Rats, Sprague-Dawley ; Spermatogonia ; cytology ; enzymology ; ultrastructure ; Telomerase ; antagonists & inhibitors ; genetics ; metabolism

Telomerase activity is usually detected in most tumor tissues but not in normal tissues. Recently, there is increasing evidence that telomerase activity is associated with cell proliferation without malignancy, whereas there is little information about telomerase activity and its relationship with cell proliferation in chronic hyperproliferative skin diseases. Thus, we studied telomerase activity in skins from 10 patients with psoriasis and compared telomerase activity with the expression of Ki-67, a proliferation marker, using immunohistochemical staining. The effect of retinoic acid on the telomerase activity in HaCaT cells was also evaluated. Telomerase activity was detected in 7 (70%) of 10 lesional skins of psoriasis and none of the nonlesional skin. Telomerase activity in lesional skin was significantly associated with Ki-67 labelling index. Retinoic acid treatment on HaCaT cells inhibited telomerase activity, which correlated with inhibition of cell proliferation by the agent. The results of our study represent another example that shows telomerase activity correlates with cellular proliferation. Further studies on the regulation of the telomerase are needed to understand the cellular factors involved in controlling telomerase activity.
Cell Division/drug effects ; Cell Line ; Enzyme Inhibitors/*pharmacology ; Human ; Ki-67 Antigen/*analysis ; Psoriasis/*enzymology ; Skin/*enzymology ; Telomerase/antagonists & inhibitors/*metabolism ; Tretinoin/*pharmacology

The gene for LPTS is originally cloned as a human liver-related putative tumor suppressor (LPTS) gene that encodes a full length protein of 328 amino acids (LPTS-L). LPTS-L is also identified as a telomerase inhibitor to regulate telomere length in the cells. To facilitate the functional and structural studies of LPTS-L protein, the cDNA for LPTS-L was cloned into the expression vector pET-24 in frame to generate a recombinant plasmid pET-24-LPTS. The LPTS-L protein was expressed in E. coli BL21 solublely, and purified by Ni Sepharose affinity chromatography which, however, is not fit for large scale protein purification. The gene of LITS-L was then PCR amplified to remove the 6 x His tag, and cloned into pET-24a. The non-fusion protein of LPTS-L was expressed in E. coli B21, and purified by phosphocellulose P11 chromatography. The purity of LPTS-L protein was about 55% after that procedure,and arrived at 80% after second purification by Sephadex G-100 chromatography. Western Blotting analysis showed that the band reflects the specific binding of anti-LPTS antiserum against the purified LPTS-L protein. The TRAP assay was performed to detect the telomerase inhibitory activity of LPTS-L protein in vitro. It was observed that the purified LPTS-L inhibited the activity of telomerase greatly, similarly with that of LPTS-L protein purified by Ni Sepharose 4B. Our results suggest that phosphocellulose P11 plus Sephadex G-100 chromatography could substitute for Ni Sepharose 4B affinity chromatography for preparation of purified LPTS-L protein. Through this study, a technique for preparation of LPTS-L protein in a large scale is established.
Animals ; Cloning, Molecular ; Escherichia coli ; genetics ; metabolism ; Humans ; Recombinant Proteins ; biosynthesis ; genetics ; isolation & purification ; Recombination, Genetic ; Telomerase ; antagonists & inhibitors ; Tumor Suppressor Proteins ; biosynthesis ; genetics

To explore the effect of human telomerase reverse transcriptase (hTERT) gene antisense oligodeoxynucleotide (ASODN) on telomerase activity in primary acute myeloid leukemia (AML) cells and chronic myeloid leukemia (CML) cells, polymerase chain reaction enzyme-linked immunosorbent assay (PCR-ELISA) was used to determine telomerase activity. The expression levels of hTERT protein were assayed by flow cytometry using immunofluorescence labeling. Immunofluorescence assay showed that the expression levels of hTERT protein in AML and CML cells decreased with time after hTERT ASODN treatment. There was no difference in hTERT protein levels between control and sense oligodeoxynucleotide (SODN)-treated cells. Telomerase activity decreased when AML and CML cells were treated with ASODN for 48 h. Telomerase activity of AML and CML cells was significantly inhibited when the cells treated with ASODN for 72 h. There was no difference in telomerase activity levels between control and hTERT SODN-treated cells. It was concluded that hTERT ASODN could inhibit hTERT protein expression level, thus decreasing the telomerase activity in primary AML and CML cells.
Adolescent ; Adult ; DNA-Binding Proteins ; Female ; Humans ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive ; enzymology ; Leukemia, Myeloid, Acute ; enzymology ; Male ; Middle Aged ; Oligodeoxyribonucleotides, Antisense ; pharmacology ; Telomerase ; antagonists & inhibitors ; metabolism

OBJECTIVETo clarify growth inhibition in pancreatic cancer cells by interference with the hTR component of the telomerase reverse transcriptase enzymatic complex.

METHODSA 593 bp full length hTR cDNA was subcloned into a mammalian expression vector pcDNA3.1(-) in the antisense orientation to construct an antisense hTR expression plasmid. These were introduced into panc1 cells, a human pancreatic carcinoma cell line, by lipofectin and G418-resistant stable transformants were expanded. Resulting stable clones were screened for the presence of the hTR insert by PCR with T7 and BGH reverse primers located on the flanks of the multiclonal site of the pcDNA3.1 vector. Cell growth rate, hTR expression, telomerase activity and anchorage-independent growth properties were analyzed.

RESULTSSignificant downregulation of endogenous hTR was evident in the antisense-hTR transformed cells and telomerase activity was markedly decreased compared to control cells in standard TRAP assays. Furthermore, cell proliferation and the anchorage-independent growth ability in antisense-hTR expressing cells were significantly decreased compared with control parental cells. However, no crisis or senescence phenomena were observed.

CONCLUSIONSThese data indicate that hTR may be a critical component of human telomerase activity and suggest that downregulation of the RNA component of human telomerase is a possible target for anticancer strategies.

DNA-Binding Proteins ; Humans ; Pancreatic Neoplasms ; pathology ; therapy ; RNA, Antisense ; therapeutic use ; Reverse Transcriptase Polymerase Chain Reaction ; Telomerase ; antagonists & inhibitors ; genetics ; Tumor Cells, Cultured

This study was purposed to investigate the effect of 3'-azido-2', 3'-dideoxythymidine (AZT)on the proliferation and telomerase activity of human acute myeloid leukemia cell line KG-1a. The effect of proliferation was detected by MTT assay after the KG-1a cell were stimulated for 24, 48 and 72 h with different concentrations of AZT; telomerase activity was detected with TRAP-PCR-ELISA assay; RT-PCR was used to detect telomerase hTERT mRNA expression. The results showed that the proliferation of KG-1a cells was inhibited in a time and concentration dependent manner after exposure to AZT for 24, 48 and 72 h; the KG-1a cells decreased in S phase and increased in G(2)/M phase with the increasing of the concentration of AZT; telomerase activity and hTERT-mRNA expression in the experimental groups decreased after treated with AZT, which was positively correlated with concentration of AZT. It is concluded that AZT inhibits KG-1a cell proliferation and induces apoptosis, which maybe related with its decreasing the telomerase activity and hTERT mRNA expression.
Apoptosis ; drug effects ; Cell Cycle ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; Humans ; Leukemia ; metabolism ; pathology ; Telomerase ; antagonists & inhibitors ; metabolism ; Zidovudine ; pharmacology

BACKGROUNDPeptide nucleic acid (PNA) has many characteristics useful in molecular biology. This paper described an effective way to raise the cell ingestion rate of PNA so as to kill gastric cancer cells.

METHODSHeteroduplexes of PNAs and oligonucleotides, wrapped by Lipofectamine 2000, were used to infect SGC7901 cells. The inhibitive effect of heteroduplexes was evaluated by analyzing cell clone forming and cell growth rate. Telomerase activity of SGC7901 cells was detected by polymerase chain reaction enzyme-linked immunosorbent assay (PCR-ELISA) and silver staining assay.

RESULTSPNAs showed a dose-dependent inhibition of cell proliferation. The percentage of proliferation inhibition was 99.4% after 7 days; the rate of cloning inhibition was 98.2% after 8 days; whereas for oligonucleotide groups, at the same concentration, the percentages were 50.1% and 67.5% respectively. Antisense PNA-DNA-Lipofectamine 2000 group (AP-D-L group) exhibited significantly different percentages from the control groups (P < 0.05). The test result indicated that telomerase activity of the AP-D-L group was inhibited (P < 0.05). At the same time, the impact on cell morphology was observed.

CONCLUSIONSThe results showed that PNAs are potent antisense reagents. The telomerase-associated therapies are very promising for the treatment of malignant tumours.

Cell Division ; drug effects ; Cell Line, Tumor ; DNA-Binding Proteins ; Humans ; Peptide Nucleic Acids ; therapeutic use ; Stomach Neoplasms ; pathology ; therapy ; Telomerase ; antagonists & inhibitors ; metabolism ; Transfection

OBJECTIVETo evaluate antisense technology for human telomerase inhibition in the treatment of endometrial cancer.

METHODSAn antisense oligodeoxynucleotides (AODN) directed against the human telomerase transcriptase (hTERT), designed and synthesized to serve as a telomerase inhibitor, was transfected into endometrial carcinoma cell line HEC-1A by lipofectin. Reverse transcription-polymerase chain reaction (RT-PCR) and Western blot were used to test the expression of hTERT mRNA and hTERT protein before and after transfection. Telomerase activity was tested by telomeric repeat amplification protocol. The proliferation and growth of HEC-1A were also studied by methyl thiazolyl tetrazolium and cell growth curve before and after transfection.

RESULTSAODN could down-regulate the expression of hTERT mRNA and protein, inhibiting telomerase activity and proliferation of endometrial cancer cell line in a dose- and period-dependent manner.

CONCLUSIONAntisense oligodeoxynucleotides of human telomerase transcriptase definitely inhibits the proliferation of endometrial cancer cell line. Telomerase inhibitor may thus become a new gene therapeutic agent for endometrial carcinoma.

Caspases ; metabolism ; Cell Line, Tumor ; Cell Proliferation ; Endometrial Neoplasms ; pathology ; therapy ; Female ; Genetic Therapy ; Humans ; Oligonucleotides, Antisense ; genetics ; RNA, Messenger ; analysis ; Telomerase ; antagonists & inhibitors ; genetics

This study was aimed to construct a plasmid expressing siRNA specific for the human telomerase reverse transcriptase (hTERT) gene and to evaluate the ability of small interference RNA(siRNA) for inhibiting telomerase activity in HeLa cells. 64 nucleotides, in which 19 nt were homologous with hTERT gene, were chemically synthesized, annealed and linked into pSUPER to get pSUP-hTE. Then pSUP-hTE was digested with enzyme. We obtained its fragmant concluding promoter and 64nt. So we cloned it into pEGFP-C1 for constructing pEGFP-hTE which contains neo gene and the enhanced green fluorescent protein (EGFP). Recombinant pEGFP-hTE was transfected to HeLa cells. These cells were screened with medium containing G418. When stable colonies appeared, G418-resistant cells were harvested and propagated. At the different cell generations, hTERT mRNA and protein expression, telomerase activity and cell growth activity were analyzed. Compared with control cells, HeLa cells transfected with pEGFP-hTE showed that hTERT mRNA level and hTERT protein expression decreased and telomerase activity reduced by 38%, but the cells growth activity displayed no changes. So pEGFP-hTE could specifically inhibit expression of hTERT and telomerase activity. These results suggested that siRNA targeting hTERT gene might provide a new strategy for cancer biotherapy.
Base Sequence ; Gene Expression Regulation, Enzymologic ; Gene Expression Regulation, Neoplastic ; HeLa Cells ; Humans ; Molecular Sequence Data ; Plasmids ; genetics ; RNA, Small Interfering ; genetics ; pharmacology ; Telomerase ; antagonists & inhibitors ; genetics ; Transfection