Study on mechanism difference of baicalein and wogonin inhibiting energy metabolism of hepatoma cells / 中国药房

OBJECTIVE To explore the difference in th e mechanis m of baicalein and wogonin inhibiting the energy metabolism of hepatoma cells. METHODS Human hepatoma HepG 2 cells were divided into blank control group （without medicine），different dose groups of baicalein and wogonin （1.25，2.5，5，10 and 20 μmol/L）. The effects of baicalein and wogonin on the viability of HepG 2 cells were detected by MTT assay. HepG 2 cells were divided into blank control group （without medicine），baicalein group and wogonin group. After administration ，the concentration of ATP in cell was detected by enhanced ATP kit. The levels of cell glycolysis and mitochondrial energy metabolism were evaluated by glycolysis and mitochondrial pressure test kit ；the affinity of baicalein and wogonin with key enzymes of energy metabolism was predicted by molecular docking ，and the key enzymes of energy metabolism with high affinity were screened ；the expression of key enzymes of energy metabolism was detected by Western blot. RESULTS Within the dose range of 2.5-20 μmol/L，the half inhibitory concentrations of baicalein and wogonin were 12.84 and 24.09 μmol/L；baicalein 1.25 μmol/L and wogonin 2.5 μmol/L had no effect on cell viability ，so it was selected as the dosage for subsequent experiments. Compared with blank control group ，the concentration of ATP in HepG 2 cells decreased significantly in baicalein group and wogonin group （P＜0.05）；the inhibitory effects on basic acidification rate of HepG 2 cells in wogonin group were significantly stronger than those of baicalein group （P＜0.05），but there was no significant difference between them on the basic oxygen consumption rate （P＞0.05）；baicalein had strong binding to pyruvate kinase M 2 and mitochondrial enzyme complexes Ⅰ（CⅠ），C Ⅱ and C Ⅳ，while wogonin only had strong binding to pyruvate kinase M 2； wogonin could significantly down-regulate the protein expressions of hexokinase ，phosphofructokinase，pyruvate kinase M 2，CⅠ， C Ⅱ and C Ⅳ（P＜0.05），but there was no statistical significance in the effect of baicalein on the regulation of these enzymes （P＞ 0.05）. CONCLUSIONS Both baicalein and wogonin can inhibit the energy metabolism of hepatoma HepG 2 cells，but the mechanism is different ：the effect of baicalein is related to the activity of key enzymes ，while the effect of wogonin is related to the inhibition of the expression of key enzymes of energy metabolism.

Screening of optimal siRNA interference sequence of CIT gene and its inhibition expression in hepatoma SK-Hep-1 / 中华肝脏病杂志

Objective@#To construct and screen optimal siRNA interference sequence of CIT gene and to detect its interference efficiency as well as proliferation effect in human hepatoma cell line SK-Hep-1.@*Methods@#Three siRNA target spots were designed and synthesized according to the CIT gene sequence. SK-Hep-1 HCC cells were transfected by liposome transfection. The knockdown efficiency of the target CIT gene was detected by real-time PCR and Western blot. Expressional change of CIT in SK-Hep-1 cells after 48 hours of siRNA interference were observed by immunohistochemistry and confocal microscopy. The proliferation of SK-Hep-1 cells after 48 hours of siRNA interference was detected by EdU cell proliferation assay. A t-test was used to compare the mean of two samples, and one-way ANOVA was used to compare the mean of multiple samples.@*Results@#Western blot results showed that the three interference sequences were targeted at different target spots. The expression level of CIT protein in KD-1,-2, and-3 groups were decreased (P < 0.01) than control, while the protein expression level of KD1 group was the lowest. Real-time PCR results showed that compared with the control group, the expression level of CIT mRNA in KD-1, -2, and -3 groups decreased (P < 0.01), while that in KD1 group was the lowest. Laser confocal microscopy also confirmed that the morphological expression of CIT attenuated significantly after transfection with siRNA. The results of EdU proliferation assay showed that siRNA transfected with CIT significantly attenuated the proliferation of SK-Hep-1 hepatoma cells (P < 0.05).@*Conclusion@#The successful construction and screening of siRNA fragments can effectively inhibit the expression and proliferation of CIT gene in hepatoma SK-Hep-1.

Inhibitory Effect of Total Alkaloids from Lotus Seed on Human Hepatoma Cells / 中国药师

Objective: To study the inhibitory effect of total alkaloids from lotus seed on human hepatoma HepG2 cells.Methods: The effect of total alkaloids from lotus seed on the growth of HepG2 cells was studied by CCK-8 kit.The apoptosis rate of HepG2 cells was detected by flow cytometry.Results: When the action time was the same, with the increase of drug concentration, the inhibitory rate of total alkaloids from lotus seed on HepG2 cells increased, in a dose-dependent manner.At 72 h, the half inhibitory concentration (IC50) of total alkaloids from lotus seed on HepG2 cells was 1.501 μg·ml-1.At the same concentration, the inhibitory rate of the total alkaloids from lotus seed on HepG2 cells increased with the extension of the action time.At 72 h, the inhibition rate of 10 μg·ml-1 total alkaloids from lotus seed reached 72%.After treated with the total alkaloids from lotus seed at different concentrations, the apoptosis rate of HepG2 cells significantly increased in a dose-dependent manner.Compared with the blank control group, the difference was statistically significant (P <0.05), and the apoptosis rate of HepG2 cells was 85.6% treated with 20 μg·ml-1 total alkaloids from lotus seed.Conclusion: The total alkaloids from lotus seed can induce cell apoptosis and inhibit the proliferation of human hepatoma HepG2 cells.

Effects of Betulinic Acid on Proliferation of Human Liver Cancer HepG2 Cells / 中国中医药信息杂志

Objective To observe the effects of betulinic acid (BA) on proliferation of human hepatoma stem cell;To discuss its anti-cancer mechanism from the aspects of cell cycle and cell apoptosis. Methods HepG2 stem cells were cultivated in vitro and testified the self-renewal capacity. The effects of BA in concentration of 40, 20, 10, 5, 2.5, 1.25μmol/L on the cell vitality of cultured human liver cancer stem cells for 24 and 48 hours were measured with CCK-8 method. The human hepatoma stem cell line HepG2 was administrated by BA at concentrations of 40, 20, 10, 5μmol/L for 48 hours, and cell cycle and apoptosis rate were measured by flow cytometry. Results BA could inhibit HepG2 stem cell proliferation obviously with dose-effect relationship. BA influenced cell cycle, and induced tumor stem cell apoptosis. 40μmol/L BA blocked cell cycle in S phase, and cell apoptosis rate reached 10.86%. Conclusion BA has obvious inhibitory effects on proliferation of HepG2 liver cancer stem cell, which probably plays a part in anti-cancer by influencing cell cycle and inducing cell apoptosis.

Micro electrochemical mechanism of baicalin-metal complexes binding with hepatoma SMMC-7721 cell DNA / 中草药

Objective: The correlation of baicalin-metal (Y3+, La3+, and Ce3+) complexes (BMC) anti-tumor activity and the interactional ability of BMC binding with hepatoma SMMC-7721 cell DNA was investigated. Methods: Hepatoma SMMC-7721 cells DNA was extracted as a target, cyclic voltammetry and AC impedance were utilized to study the interaction between BMC and DNA, and the interaction mechanism between BMC and DNA was explored. Results: BMC and hepatoma SMMC-7721 cell DNA formed a non-electroactive supramolecular compounds through mixed-mode of electrostatic interaction, binding number m = 1, binding constant βBC = 1.27 × 105 L/mol, βBC-Y = 3.46 × 105 L/mol, βBC-La = 6.24 × 105 L/mol, and βBC-Ce = 7.29 × 106 L/mol. After BC binding with metal ions, its ability of binding to DNA significantly enhanced, and the strength order: BC-Ce > BC-La > BC-Y > BC. Conclusion: The ability of BMC binding with DNA consists with its cytotoxicity. After BMC binding with SMMC-7721 cell DNA, it could inhibit the cell proliferation and lead to the cell apoptosis, which illustrates the BMC exhibits an anti-tumor activity. The relevant results have given a reference for the study on the new anti-tumor complexes of Chinese materia medica.

Mechanism of phloretin induced the apoptosis of hepatoma carcinoma cell SMMC-7721 / 中国生化药物杂志

[Abstract ] Objective To investigate effect of phloretin on apoptotic of hepatoma carcinoma cells SMMC-7721, and explore its mechanisms.Methods Logarithmic phase of hepatoma carcinoma cells SMMC-7721 were cultured separately with 30, 60, 120 mg/L phloretin, morphological alterations of apoptotic were observed by phase contrast microscopy and AO/EB double fluorescence staining method was used to observe were low, medium and high concentration trentment group, respectively.the cells treated by phloretin.Apoptotic rates, cell cycle progression, mitochondrial trans-membrane potential and intracellular calcium homeostasis were detected by flow cytometry.Results Cells appeared typical apoptosis morphological alterations.Phloretin induced SMMC-7721 cell line apoptosis in a dosage and duration dependent manner.Cell cycle was arrested at G1 phase, mitochondrial trans-membrane potential decreased, intracellular free Ca2 +increased.Conclusion Phloretin induce apoptosis of SMMC-7721 by affecting cell cycle progression, reducing mitochondrial trans-membrane potential and changing intracellular calcium homeostasis.

Effects of proliferation and apoptosis of phloretin on the hepatoma carcinoma cells HepG-2 / 中国生化药物杂志

Objective To investigate proliferative and apoptotic effects of phloretin on hepatoma carcinoma cells, hepatoma carcinoma cells HepG-2 was used as research materials.Methods This research observed morphological alterations using phase contrast microscopy and electron microscopy, cell proliferation were detected by MTT assay, and using flow cytometry detected apoptotic rates, cell cycle progression, mitochondrial trans-membrane potential and intracellular calcium homeostasis.ResuIts Apoptotic cells appeared morphological alterations.Phloretin exerted a inhibitory the proliferation of HepG-2 cell line, and induced its apoptosis in a dosage and duration dependent manner.Cell cycle was arrested at G1 phase, mitochondrial trans-membrane potential dropped, intracellular free Ca2 + increased.ConcIusion Phloretin can induce apoptosis of HepG-2 via arresting cell cycle progression, reducing mitochondrial trans-membrane potential and disturbing intracellular calcium homeostasis.

The forecast of anticancer targets of cryptotanshinone based on reverse pharmacophore-based screening technology / 中国天然药物

Anticancer targets of cryptotanshinone were evaluated and rapidly forecasted with PharmMapper, a reverse pharmacophore-based screening platform, as well as drug target databases, including PDTD, DrugBank and TTD. The pathway analyses for the collection of anticancer targets screened were carried out based on the KEGG pathway database, followed by the forecast of potential pharmacological activities and pathways of the effects of cryptotanshinone, and verification of some of the targets screened using whole cell tests. The results showed that a total of eight targets with anticancer potential were screened, including MAP2K1, RARα, RXRα, PDK1, CHK1, AR, Ang-1 R, and Kif11. These targets are mainly related to four aspects of the cancer growth: the cell cycle, angiogenesis, apoptosis, and androgen receptor. The cell tests showed that cryptotanshinone can inhibit the viability of human hepatoma cells SMMC-7721, which is related to the reduction of expression of MAP2K1 mRNA. This method provides a strong clue for the study of the anticancer effects and mechanisms of action of cryptotanshinone in the future.

Pro-Apoptosis Effects of Danhong Injection on the SMMC-7721 Hepatoma Cells / 医药导报

Objective To investigate the effects of danhong injection on the apoptosis of SMMC-7721 heptoma cells.Methods The hepatocellular carcinoma cell line SMMC-7721 was incubated with different concentrations(0,2,4,8 μL·mL-1) of danhong injection, and cell morphology was studied under the microscope. The apoptosis index was detected by flow cytometry at 0,6,12,24 h after cultured with 2 μL·mL-1danhong injection. Cell proliferation was measured by MTT assay;Gene expressions of p53,Bax and Bcl-2 were detected by RT-PCR at different drug concentrations. Results The morphology of the hepatoma cells changed obviously,and the apoptosis index increased by danhong injection in a dose-dependant manner. The danhong injection decreased gene expressions of Bcl-2,and obviously increased p53 and Bax. Conclusion Danhong injection can dose-and time-dependently promote apoptosis of SMMC-7721 cells.

Effects of Resveratrol Combined with Radiotherapy on Human Hepatoma Cell Line Bel-7404 in Vitro / 医药导报

Objective To investigate the effects of radiotherapy combined with resveratrol( Res)on proliferation, invasion and apoptosis of hepatoma cell line Bel-7404. Methods Bel-7404 cell line was treated with Res(25 μmol·L-1 ) combined with radiotherapy,then divided into four groups( group 1:the control;group 2:radiation at dose of 2 Gy;group 3:radiation at dose of 4 Gy;group 4:radiation at dose of 6 Gy). Cell proliferation and invasion were detected by MTT assay. Cell apoptosis were observed by fluorescence microscopy. Expressions of MMP-2 and VEGF proteins were determined by Western blotting. Results Compared with the control group,cell proliferation and invasion were significantly inhibited,while cell apoptosis was increased in all radiation groups(P〈0. 05). Conclusion The sensitivity of hepatoma Bel-7404 cells to radiation can be enhanced by resveratrol. Radiation therapy combined with resveratrol can inhibit proliferation and invasion of hepatoma cells and increase the cell apoptosis,which may be related with the down-regulation of MMP-2 and VEGF proteins.

Hepatic carcinoma HepG2 cell proliferation and its cellular autophagy by the Nrf2-ARE pathway / 国际外科学杂志

Objective To explore the influence of HepG2 cells' proliferation and autophagy by the Nrf2-ARE pathway,and provide the experimental basis for clinical exploring effective liver cancer treatment.Methods Hepatic carcinoma HepG2 cells were cultured,and its proliferation inhibition rates and the change of cell cycle' s in each phase were explored by the MTT assay and flow cytometry.The hepatoma cells' autophagy was qualitative observed by inverted phase contrast microscope and fluorescence microscope.Results Inhibitory rate of HepG2 cells was obviously higher in the Nrf2 inhibitor BML-111 group than control group (P ＜ 0.05),and the control group was aslo obviously higher than the Nrf2 inducer EGb group (P ＜ 0.05).Flow cytometric analysis showed that G1 phase cells in the cell cycle increased,S phase cells reduced and G2/M period cells relatively increased in the Nrf2 inhibitor BML-111 group.But G1 phase cells reduced,S phase cells increased and G2/M period cells relative reduced in the Nrf2 inducer EGb group.Inverted phase contrast microscope and fluorescence microscope checked that ranging from the size of the bubble and autophagosome formed in Hepatoma HepG2 cytoplasmic of the Nrf2 inhibitor BML-111 group.Conclusions The Nrf2-ARE pathway played an reverse inhibition on HepG2 cells' proliferation and autophagy.After the inhibition of Nrf2-ARE pathway,HepG2 cells mostly stayed in the G1 phase of the cell cycle.

Effects of Benzo(a)pyrene on the Expression of Heat Shock Proteins, Pro-inflammatory Cytokines and Antioxidant Enzymes in Hepatic Tumors Induced by Rat Hepatoma N1-S1 Cells

Benzo(a)pyrene (BaP) is a polycyclic aromatic hydrocarbon (PAH) that is easily introduced to humans via consumption of grilled or smoked meat. BaP causes harmful oxidative effects on cell development, growth and survival through an increase in membrane lipid peroxidation, oxidative DNA damage and mutagenesis. Therefore, the present study was conducted to evaluate the synergistic effects of BaP on oxidative stress in hepatic tumors. In this study, we established a hepatic tumor model by injecting rat hepatoma N1-S1 cells into healthy rats. Changes in the abundance of heat shock proteins (HSPs), antioxidant enzymes and pro-inflammatory cytokines were then investigated by western blot analysis. In addition, we examined changes in oxidative stress levels. Injection of N1-S1 cells or concomitant injection of BaP and N1-S1 cells resulted in the formation of hepatic tumors at the injection site. Evaluation of rat plasma reveals that hepatic tumors induced by BaP and N1-S1 cells expresses higher levels of Hsp27, superoxide dismutase (SOD), and tumor necrosis factor-alpha (TNF-alpha) when compared to those induced by N1-S1 cells only. The collective results of this study suggest that BaP exerts synergistic effects on the expression of HSP, cytokines and antioxidant enzymes in hepatic tumors induced by rat hepatoma N1-S1 cells.

Salvianolate induces apoptosis of human hepatoma SMMC-7721 cells through mitochondrial pathway / 中国肿瘤生物治疗杂志

Objective: To explore the apoptosis-inducing effect of salvianolate on hepatoma SMMC-7721 cells and the underlying mechanism. Methods: SMMC-7721 cells were co-cultured in vitro with different concentrations (0.5, 1, 2 mg/ml) of salvianolate for 24 h. The apoptotic SMMC-7721 cells were examined by flow cytometry, and the changes of mitochondrial transmembrane potential were examined by mitochondrial transmembrane potential JC-1 kit. The activities of caspase-8, caspase-9, and caspase-3 were detected by spectrophotometry in the hepatoma SMMC-7721 cells after co-cultured with 1 mg/ml salvianolate. The changes of apoptotic SMMC-7721 cells induced by salvianolate in the presence or absence of caspase-9 inhibitor or caspase-3 inhibitor were measured by flow cytometry. The expressions of pro-apoptotic protein Bax and anti-apoptotic protein Bcl-2 were detected by Western blotting analysis. Results: Salvianolate significantly induced apoptosis of hepatoma SMMC-7721 cells (P<0.05), and the decline of mitochondrial membrane potential increased with the increase of salvianolate concentration (P<0.05). The activities of caspase-9 and caspase-3, but not caspase-8, were increased in hepatoma cells after treatment with 1 mg/ml salvianolate for 24 h (P<0.05). The apoptosis-inducing effect of salvianolate was significantly decreased in the presence of caspase-9 or caspase-3 inhibitors (P<0.05). Western blotting results showed that salvianolate increased pro-apoptotic protein Bax expression and decreased anti-apoptotic protein Bcl-2 expression. Conclusion: Salvianolate can induce the apoptosis of human hepatoma SMMC-7721 cells in a dose-dependent manner, which is probably mediated by mitochondrial apoptosis pathway.

The role mechanism of alpha fetoprotein in escaping immune surveillance of hepatoma cells / 肿瘤研究与临床

Alpha fetoprotein(AFP) plays multi-role in regulating the growth of hepatocellular carcinoma cells, because of AFP has a complex molecular structure. AFP not only can promote the proliferation of hepatoma cells, but also can inhibit the immune response in liver cancer patients. Recently, documents showed that AFP has a capability to impair the function of dentritic cells(DCs), and AFP could induce DCs to death. AFP restrain DCs transform to matured antigen presenting cell through regulating the phenotype molecule express in the membrane of DCs, and AFP also influence the expression of tumor necrosis factor family and its receptor in lymphocytes or in hepatoma cells, AFP also could inhibit the activity of caspase in tumor cells, possesses these effects of AFP result in the hepatoma cells escape the immune surveillance.

Effects of transforming growth factor 1 and hypoxia on the expression of vascular endothelial growth factor for Hepatoma cells / 基础医学与临床

Objective To observe the effect of Vascular Endothelial Growth Factor(VEGF) to the expression in hepatoma cells affected by TGF-?1 and hopxia. Methods HepG2 cells were cultured in vitro, and treated with different doses of TGF-?1 and Cobalt chloride hexahydrate(CoCl2), or with TGF-?1 and CoCl2. The change of VEGF protein and mRNA was detected by immunohistochemistry and semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR). Results Immunohistochemistry and RT-PCR showed that the expression of VEGF protein and mRNA were significantly higher in TGF-?1 groups or CoCl2 groups than that of control group(P

Involvement of mitogen-activated protein kinases and p21Waf1 in hydroxyurea-induced G1 arrest and senescence of McA-RH7777 rat hepatoma cell line

Hydroxyurea is commonly used to treat hematologic disorders and some type of solid tumors, but the mechanism for its therapeutic effect is not clearly known. In this study, we examined the effect of hydroxyurea on rat hepatoma McA-RH7777 cells, specifically, on the role of mitogen-activated protein (MAP) kinase signal transduction pathways and p21Waf1, p27Kip1 and p53. Rat hepatoma McA-RH7777 cells treated with hydroxyurea for 7 days, caused the inhibition of cell growth in a dose-dependent manner. But, this growth inhibition was not caused by necrosis or apoptosis but instead was associated with cell senescence-like change as evidenced by senescence associated-beta-galactosidase staining, and cells arrest at G1 phase of cell cycle. Phosphorylation of MAP kinases, such as ERK, JNK, and p38, was found to be decreased after treatment of cells with hydroxyurea. But, the expression of p21Waf1 was increased, while p27Kip1 and p53 were not detected in hydroxyurea treated rat hepatoma cells. Hydroxyurea treatment induced G1 arrest and a senescence-like changes in rat hepatoma McA-RH7777 cells may be the likely results of signal disruption of MAP kinases (ERK, JNK, and p38 MAP kinase) and p21Waf1 over-expression.

Effects of the total extract of astragalosides on the growth, AFP secretion and γ-GT activity of human hepatoma cells / 中国临床药理学与治疗学

AimTo study the effect of the total extract of astragalosides(TEA) on the growth, AFP secretion and γ-GT activity of human hepatoma cells invitro.Methods The human hepatoma HepG2 and Bel-7404 cells were cultured with TEA 5～160 mg · L-1 for 6 days. Anti-hepatoma activity was measured by MTT method. AFP was assaysed by ELISA and γ-GT was determined by enzyme-substrate method. Results The growth of the human hepatoma HepG2 and Bel-7404 cells and the secretion of AFP of HepG2 cells were reduced significantly by TEA 5～160 mg· L-1. The γ-GT activity of HepG2 cells was inhibited and its ALB content was increased by TEA 20, 40 and 80 mg · L-1. The γ-GT activity of Bel-7404 cell was inhibited and its ALB content was increased byTEA 40 and 80 mg · L-1 Conclusion These results suggest that TEA has inhibitory effects on the growth, AFP secretion and γ-GT activity of human hepatoma cells.

Effects of the total extract of astragalosides on the growth,AFP secretion and ?-GT activity of human hepatoma cells / 中国临床药理学与治疗学

Aim To study the effect of the total extract of astragalosides (TEA) on the growth, AFP secretion and ?_GT activity of human hepatoma cells in vitro. Methods The human hepatoma HepG2 and Bel_7404 cells were cultured with TEA 5～160 mg?L-1 for 6 days. Anti_hepatoma activity was measured by MTT method. AFP was assaysed by ELISA and ?_GT was determined by enzyme_substrate method. Results The growth of the human hepatoma HepG2 and Bel_7404 cells and the secretion of AFP of HepG2 cells were reduced significantly by TEA 5～160 mg?L-1.The ?_GT activity of HepG2 cells was inhibited and its ALB content was increased by TEA 20,40 and 80 mg?L-1. The ?_GT activity of Bel_7404 cell was inhibited and its ALB content was increased by TEA 40 and 80 mg?L-1.Conclusion These results suggest that TEA has inhibitory effects on the growth, AFP secretion and ?_GT activity of human hepatoma cells.

Triton X-100 induces apoptosis in human hepatoma cell lines

The detergent Triton X-100 was used to establish a model for apoptosis in hepatoma cell lines. The electrophoresis of DNA extracted from 0.01% Triton X-100 treated hepatoma cell lines showed DNA ladder formation, a hallmark of apoptosis. The DNA fragmentation appeared within less than 60 min of the Triton X-100 treatment. Chromatin condensation and apoptotic bodies were observed by hematoxylin and eosin (H & E) stain, and fragmented nucleosome was detected by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labelling (TUNEL) test. Apoptosis was semi-quantitated by measuring the lactate dehydrogenase (LDH) level for cytotoxity. It was found that apoptosis had been induced in more than 90% of the cells treated with Triton X-100 for 150 min. These data show that Triton X-100 efficiently induces the apoptotic cell death in hepatoma cell lines.

Adaptive response to ionizing radiation induced by low dose of gamma ray in human hepatoma cell lines

When cells are exposed to a low dose of a mutagenic or clastogenic agent, they often become less sensitive to the effects of a higher dose administered subsequently. Such adaptive responses were first described in Escherichia coli. Studies on mammalian cells have been limited to human lymphocytes exposed to low doses of an alkylating agent. In this study, the adaptive response to 1 cGy of gamma rays was investigated in human tumor cells using two human hepatoma cell lines, Hep G2 and Hep 3B. Experiments were carried out by delivering 1 cGy followed by 50 cGy of gamma radiation and chromatid breaks were scored as an endpoint. The results of this study indicate that prior exposure to 1 cGy of gamma rays reduces the number of chromatid breaks induced by subsequent higher doses (50 cGy). The time necessary for the expression of the adaptive response was determined by varying the time interval between the two doses from 1 hour to 72 hours. In G2 chromatids, the adaptive response was observed both at short time intervals, as early as 1 hour, and at long time intervals. In S chromatids, however, the adaptive response was shown only at long time intervals. When 3-aminobenzamide, an inhibitor of poly (ADP-ribose) polymerase, was added after 50 cGy, adaptive responses were abolished in all the experimental groups. Therefore, it is suggested that the adaptive response can be observed in human hepatoma cell lines, which is first documented through this study.