• Asian Pacific Journal of Cancer Prevention
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• v.14 no.6
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• pp.3449-3453
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• 2013

Background: Telomerase has been considered as an attractive molecular target for breast cancer therapy. The main objective of this work is to assess the inhibitory effects of silibinin and curcumin, two herbal substances, on telomerase gene expression in breast cancer cells. Materials and Methods: For determination of cell viability tetrazolium-based assays were conducted after 24, 48, and 72 h exposure times and expression of human telomerase reverse transcriptase gene was measured with real-time PCR. Results: Each compound exerted cytotoxic effects on T47D cells and inhibited telomerase gene expression, both in a time-and dose-dependent manner. The mixture of curcumin and silibinin showed relatively more inhibitory effect on growth of T47D cells and hTERT gene expression as compared with either agent alone. Conclusions: These findings suggest that cell viability along with hTERT gene expression in breast cancer cells could be reduced by curcumin and silibinin.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.19 no.2
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• pp.26-39
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• 2006

Objective : The effect of water extract of Chungjogupae-tang (CJGPT) was investigated on the growth of human lung carcinoma A549 cells. Methods : MTT assay and fluorescent microscope performed to compare and examine the efficacy of CJGPT treatment on the cytostaticity of lung cancer cells in proportion to time and doses, and DAPI staining and Western blot analysis were used to examine their effect on apoptosis. In addition the quantitative RT-PCR was used to examine to lung cancer cells growth and Progtaglandin E2 and Telomerase activity were measured Results : Exposure of A549 cells to CJGPT resulted in the growth inhibition and apoptosis in a dose-dependent manner as measured by MTT assay and fluorescent microscope. The antiuoliferative effect by CJGPT treatment in A549 cells was associated with morphological changes such as membrane shrinking and cell rounding up. CJGPT treatment resulted in an up-regulation of cyclin-dependent kinase inhibitor p21(WAF1/CIPl) in a p53-independent fashion. We found that CJGPT treatment decreased the levels of cyclooxygenase (COX)-2 and inducible nitric oxide synthease (iNOS) expression without significant changes in the expression of COX-1, which was correlated with a decrease in protaglandin E2 (PGE2) synthesis. CJGPT treatment also inhibited the levels of human telomerase reverse transcriptase (hTERT) and telomerase-associated protein (TEP)-1 mRNA expression, however the activity of telomerase was slightly increased by CJGPT treatment. Conclusion : These findings suggested that CJGPT-induced inhibition of human lung carcinoma A549 cell growth was connected with the induction of apoptotic cell death and the results provided important new insights into the possible molecular mechanisms of the anti-cancer activity of CJGPT.

• Journal of Marine Bioscience and Biotechnology
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• v.1 no.4
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• pp.243-251
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• 2006

Dideoxypetrosynol A, a polyacetylene from the marine sponge Petrosia sp., is known to exhibit significant selective cytotoxic activity against a small panel of human tumor cell lines, however, the mechanisms of which are poorly understood. In the present study, it was investigated the further possible mechanisms by which dideoxytetrosynol A exerts its anti-proliferative action in cultured human leukemia cell line U937. We observed that the proliferation-inhibitory effect of dideoxypetrosynol A was due to the induction of G1 arrest of the cell cycle and apoptosis, which effects were associated with up-regulation of cyclin D1 and down-regulation of cyclin E without any change in cyclin-dependent-kinases (Cdks) expression. Dideoxypetrosynol A markedly induced the levels of Cdk inhibitor p16/INK4a expression. Furthermore, down-regulation of phosphorylation of retinoblastoma protein (pRB) by this compound was associated with enhanced binding of pRB and the transcription factor E2F-1. The increase in apoptosis was associated with a dose-dependent up-regulation in pro-apoptotic Bax expression and activation of caspase-3 and caspase-9. Dideoxytetrosynol A decreased the levels of cyclooxygenase (COX)-2 mRNA and protein expression without significant changes in the levels of COX-1, which was correlated with a decrease in prostaglandin E2 (PGE2) synthesis. Furthermore, dideoxytetrosynol A treatment markedly inhibited the activity of telomerase, and the expression of human telomerase reverse transcriptase (hTERT), a main determinant of the telomerase enzymatic activity, was progressively down-regulated by dideoxytetrosynol A treatment in a dose-dependent fashion. Taken together, these findings provide important new insights into the possible molecular mechanisms of the anti-cancer activity of dideoxytetrosynol A.

• Archives of Pharmacal Research
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• v.28 no.3
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• pp.351-357
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• 2005

Endosulfan is one of the organochlorine pesticides, which are well-known endocrine disruptors (EDs), and it acts as an estrogen agonist. Estrogen is a group of hormones that play an important role in mammary gland function and are implicated in mammary carcinogenesis. In the present study, we studied the effects of endosulfan on nodule like alveolar lesion (NLAL) formation in mouse mammary gland development using a mouse mammary gland organ culture (MMOC) system. Although endosulfan-treated mammary glands did not form NLALs, more alveolar buds were formed in this group than in the negative control (vehicle-treated) group. In addition, telomerase reverse transcriptase (TERT) mRNA expression levels were increased in endosulfan-treated mammary glands in a dose-dependent manner. Telomerase can be activated by estrogen, therefore, we examined the effects of endosulfan on telomerase activity, and found that the telomerase activity in estrogen receptor-positive MCF-7 cells was up-regulated by endosulfan treatment. Moreover, this activation was accompanied by the up­regulation of the TERT mRNA expression. Also, transient expression assays using CAT reporter plasm ids containing various fragments of the TERT promoter showed that this imperfect palindromic estrogen-responsive element is almost certainly responsible for the transcriptional activation by endosulfan. These results may help elucidate the endocrine disrupting mechanism of endosulfan.

• Journal of Life Science
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• v.19 no.4
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• pp.502-507
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• 2009

In modern oriental medicine, bee venom therapy is being used for aqua-acupuncture to relieve pain and to cure inflammatory diseases such as rheumatoid arthritis, osteoarthritis, and gout. Bee venom therapy has been processed and reported in many experimental studies, with regard to its effects on pain alleviation, anti-inflammation, removal of fever, anti-convulsion, suppression of tumor and immunity strengthening, etc., however, its mechanism of action, molecular targeting on prostaglandin $E_2$ ($PGE_2$) production and telomere length regulation in human cancer remains unclear. In this study, we investigated the effect of bee venom on the levels of cyclooxygenases (COXs) and telomere regulatory components of A549 human lung cancer cells. Bee venom-induced anti-proliferative effects of A549 cells were associated with the inhibition of human telomerase reverse transcriptase (hTERT) as well as human telomerase RNA (hTR), transcription factor c-myc and the activity of telomerase. In addition, bee venom treatment markedly decreased the levels of COX-2 mRNA and protein expression without significant changes in the expression of COX-1, which was correlated with a decrease in $PGE_2$ synthesis. Taken together, these findings provide important new insights into the possible molecular mechanisms of the anti-cancer activity of bee venom.

• Journal of Life Science
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• v.18 no.6
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• pp.884-890
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• 2008

Genistein, an isoflavone in soybean products, is a potential chemopreventive agent against various types of cancer. There are several studies documenting molecular alterations leading to cell cycle arrest at G2/M phase and induction of apoptosis; however, its mechanism of action and its molecular targets on the prostaglandin $E_2$ ($PGE_2$) production and telomere length regulation in human cancer remain unclear. In this study, we investigated the effect of genistein on the levels of cyclooxygenases (COXs) and telomere regulatory components of several human cancer cell lines (T24, human bladder carcinoma cells; U937, human leukemic cells; AGS, human stomach adenocarcinoma cells and SK-MEL-2, human skin melanoma cells). Genistein treatment resulted in the inhibition of cancer cell proliferation in a concentration-dependent manner. It was found that genistein treatment markedly decreased the levels of COX-2 mRNA and protein expression without significant changes in the expression of COX-1, which was correlated with a decrease in $PGE_2$ synthesis. Genistein treatment also partly inhibited the levels of human telomerase reverse transcriptase (hTERT) as well as human telomerase RNA (hTR) and telomerase-associated protein (TEP)-1, and the activity of telomerase. Taken together, these findings provide important new insights into the possible molecular mechanisms of the anti-cancer activity of genistein.

• Journal of Physiology & Pathology in Korean Medicine
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• v.19 no.1
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• pp.167-173
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• 2005

To investigate the possible molecular mechanism (s) of bee venom as a candidate of anti-cancer drug, we examined the effects of the compound on the growth of human lung carcinoma cell line A549. Bee venom treatment declined the cell growth and viability of A549 cells in a concentration-dependent manner, which was associated with induction of apoptotic cell death. Bee venom down-regulated the levels of anti-apoptotic genes such as Bcl-2 and Bcl-XS/L, however, the levels of Bax, a pro-apoptotic gene, were up-regulated. Bee venom treatment induced not only tumor suppressor p53 but also cyclin-dependent kinase inhibitor p21WAF1/CIP1 expression in a dose-dependent manner. Furthermore, bee venom treatment induced the down-regulation of telomerase reverse transcriptase mRNA and telomeric repeat binding factor expression of A549 cells, however, the levels of telomerase-associated protein-1 and c-myc were not affected. Taken together, these findings suggest that bee venom-induced inhibition of human lung cancer cell growth is associated with the induction of apoptotic cell death via regulation of several major growth regulatory gene products, and bee venom may have therapeutic potential in human lung cancer.

• Journal of Life Science
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• v.34 no.6
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• pp.365-376
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• 2024

The present study assessed the cytotoxic effects on cell growth and senescence in human cancer (A-549, AGS, HCT-116, MDA-MB-231, and U 87-MG) and normal (MRC-5 and mesenchymal stem cells) cell lines treated with efavirenz (EFA), an inhibitor of non-nucleoside reverse transcriptase (RTase). Following EFA treatment, the half-maximal inhibitory concentration (IC₅₀) values were approximately 15 µM, and the IC₅₀ value was significantly (p<0.05) lower in the cancer cell lines, compared to normal cell lines. After determining the IC₅₀ values against EFA, each cell line was treated with 15 µM EFA for up to one week. Significant (p<0.05) decreases in endogenous RTase and telomerase activity were observed in the cancer cell lines. RTase and telomerase activity were absent or detected at very low levels in both EFA-untreated and treated MRC-5 and MSC normal cells. The cell doubling time (CDT) was also significantly (p<0.05) prolonged by the decreased cell growth rate in the EFA-treated cancer cell lines compared to the untreated cell lines. Furthermore, EFA-treated cancer cells displayed a high number of cells with a high intensity of senescence-associated ß-galactosidase activity (SA-ß-gal activity), compared to the untreated cells. The present study showed that inhibition of RTase activity induces cellular senescence and arrests cell growth in human cancer cell lines; however, normal cell lines showed greater tolerance against EFA. RTase treatment could offer optional chemotherapy for cancer treatment in human cancer cell lines with high RTase activity.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.11
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• pp.6363-6367
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• 2013

Atractylis lancea (Thunb.) DC. (AL), an important medicinal herb in Asia, has been shown to have anti-tumor effects on cancer cells, but the involved mechanisms are poorly understood. This study focused on potential effects and molecular mechanisms of AL on the proliferation of the Hep-G2 liver cancer cell line in vitro. Cell viability was assessed by MTT test in Hep-G2 cells incubated with an ethanol extract of AL. Then, the effects of AL on apoptosis and cell cycle progression were determined by flow cytometry. Telomeric repeat amplification protocol (TRAP) assays was performed to investigate telomerase activity. The mRNA and protein expression of human telomerase reverse transcriptase (hTERT) and c-myc were determined by real-time RT-PCR and Western blotting. Our results show that AL effectively inhibits proliferation in Hep-G2 cells in a concentrationand time-dependent manner. When Hep-G2 cells were treated with AL after 48h,the $IC_{50}$ was about 72.1 ${\mu}g/mL$. Apoptosis was induced by AL via arresting the cells in the G1 phase. Furthermore, AL effectively reduced telomerase activity through inhibition of mRNA and protein expression of hTERT and c-myc. Hence, these data demonstrate that AL exerts anti-proliferative effects in Hep-G2 cells via down-regulation of the c-myc/hTERT/telomerase pathway.

• Journal of Physiology & Pathology in Korean Medicine
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• v.18 no.2
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• pp.500-506
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• 2004

The objective of the present study was to investigate the effects of aqueous extract from the healthful decoction utilizing Phellinus linteus (HDPL) on the growth of human lung carcinoma A549 cells. HDPL treatment declined the cell viability of A549 cells in a concentration-dependent manner and the anti-proliferative effects by HDPL treatment were associated with morphological changes such as membrane shrinking and cell rounding up. HDPL treatment did not affect the distribution of the cell cycle. Western blot analysis and RT-PCT data revealed that the levels of tumor suppressor p53 and cyclin-dependent kinase inhibitor p21WAF1/CIP1 in HDPL-treated A549 cells were remained unchanged. However, HDPL treatment inhibited the expression of cyclooxygenase-2 (COX-2) mRNA and protein in a concentration-dependent fashion. Additionally, the expression of human telomerase reverse transcriptase (hTERT), a main determinant of the telomerase enzymatic activity, was progressively down-regulated by HDPL treatment. Taken together, these findings suggest that HDPL-induced inhibition of human lung cancer cell proliferation is associated with the inhibition of several major growth regulatory gene products, such as COX-2 and hTERT, and HDPL may have therapeutic potential in human lung cancer.