A natural process of cirrhosis resolution and deceleration of liver regeneration after thioacetamide withdrawal in a rat model

Biased Quantification of Rat Liver Fibrosis-Meta-Analysis with Practical Recommendations and Clinical Implications

For liver fibrosis assessment, the liver biopsy is usually stained with Masson's trichrome (MT) or picrosirius red (PSR) to quantify liver connective tissue (LCT) for fibrosis scoring. However, several concerns of such semiquantitative assessments have been raised, and when searching for data on the amount of LCT in healthy rats, the results vastly differ. Regarding the ongoing reproducibility crisis in science, it is necessary to inspect the results and methods, and to design an unbiased and reproducible method of LCT assessment. We searched the Medline database using search terms related to liver fibrosis, LCT and collagen, rat strains, and staining methods. Our search identified 74 eligible rat groups in 57 studies. We found up to 170-fold differences in the amount of LCT among healthy Wistar and Sprague-Dawley rats, with significant differences even within individual studies. Biased sampling and quantification probably caused the observed differences. In addition, we also found incorrect handling of liver fibrosis scoring. Assessment of LCT using stereological sampling methods (such as systematic uniform sampling) would provide us with unbiased data. Such data could eventually be used not only for the objective assessment of liver fibrosis but also for validation of noninvasive methods of the assessment of early stages of liver fibrosis.

The combination of acyclovir and dexamethasone protects against Alzheimer's disease-related cognitive impairments in mice

Alzheimer's disease (AD) is the most common neurodegenerative disease. However, effective drugs for this disease have not yet been developed. The analysis of big data indicated that childhood herpes virus infection may be associated with the incidence of AD, suggesting that anti-herpetic drugs, such as acyclovir, may have preventive and suppressive effects in AD therapy. Moreover, short-term use of dexamethasone (DXMT), a clinical used synthetic corticosteroid, could effectively inhibit AD-related neuroinflammation. In this study, we have found that the combination of acyclovir and DXMT, but not acyclovir or DXMT alone, could protect against AD causing β-amyloid (Aβ) oligomer-induced spatial cognitive impairments. Moreover, acyclovir and DXMT could prevent Aβ oligomer-induced over-activation of microglia and astrocytes, and over-expression of pro-inflammatory cytokines, indicating that anti-AD effects of drug combination might be at least partially via neuroinflammation inhibition and immunomodulation. Furthermore, Aβ oligomer-induced decrease of PSD-95 and increase of pTau expression was prevented by the combination of acyclovir and DXMT, suggesting the involvement of synaptic protective effects of the drug combination. Taken together, our studies indicated that the combination of acyclovir and DXMT might be an alternative therapy for the treatment of AD.

The effects of concurrent treatment of silymarin and lactulose on memory changes in cirrhotic male rats

Introduction: Chronic liver disease frequently accompanied by hepatic encephalopathy (HE). Changes in the permeability of the blood-brain barrier in HE, make an easier entrance of ammonia among other substances to the brain, which leads to neurotransmitter disturbances. Lactulose (LAC), causes better defecation and makes ammonia outreach of blood. Silymarin (SM) is a known standard drug for liver illnesses. The purpose of this research was to determine the results of LAC and SM combined treatment, on the changes in memory of cirrhotic male rats. Methods: The cirrhotic model established by treatment with thioacetamide (TAA) for 18 weeks. Cirrhotic rats randomized to four groups (n = 7): TAA group (received drinking water), LAC group (2 g/kg/d LAC in drinking water), SM group (50 mg/kg/d SM by food), SM+ LAC group (similar combined doses of both compounds) for 8 weeks. The control group received drinking water. The behavior examined by wire hanging (WH), passive avoidance (PA), and open field (OF) tests.

Results: Our findings showed that treatment with SM+LAC effectively increased PA latency, compared with the control group. The results showed that the administration of LAC and SM+LAC affected the number of lines crossed, the total distance moved and velocity in the OF tests.

Conclusion: SM and LAC have anti-inflammatory effects that are memory changing. It may be due to their useful effects. These results indicated that SM+LAC restored memory disturbance and irritated mood in the cirrhotic rats. Comparable neuroprotection was never previously informed. Such outcomes are extremely promising and indicate the further study of SM+LAC.

Diethylnitrosamine and thioacetamide-induced hepatic damage and early carcinogenesis in rats: Role of Nrf2 activator dimethyl fumarate and NLRP3 inhibitor glibenclamide

Two-stage rat hepatocarcinogenesis model was used to induce early carcinogenesis in which thioacetamide (TAA) promotes diethylnitrosamine (DEN) initiated carcinogenesis. Dimethyl fumarate (DMF) used to treat multiple sclerosis, activates the nuclear factor erythroid 2-related factor 2 (Nrf2)/antioxidant responsive element (ARE) pathway during oxidative stress, and maintains antioxidant levels. Glibenclamide (GLB), a sulphonylurea drug used to treat type II diabetes, possesses anti-inflammatory properties and inhibits NLRP3 inflammasomes. The present study was designed to investigate the concurrent intervention of DMF and GLB on DEN + TAA-induced early hepatic carcinogenesis. DMF and GLB treatment improved DEN + TAA-induced decrease in body weight, increase in liver weight and plasma transaminases, histopathological alterations, DNA damage, and apoptosis. DMF and GLB intervention significantly ameliorated the DEN + TAA-induced alterations in the antioxidant (Nrf2, HO-1, SOD-1, catalase), inflammatory (NF-κB, NLRP3, ASC, caspase-1), fibrogenic (TGF-β1, collagen) and regenerative proliferative stress (GST-p, HGF, c-MET, TGFα, EGF, AFP) markers. The present results indicate that Nrf2/ARE activation and NLRP3 inhibition might be a rational approach to attenuate oxidative stress and chronic inflammation associated progression of hepatocarcinogenesis.

Indirubin Derivative 7-Bromoindirubin-3-Oxime (7Bio) Attenuates Aβ Oligomer-Induced Cognitive Impairments in Mice

Indirubins are natural occurring alkaloids extracted from indigo dye-containing plants. Indirubins could inhibit various kinases, and might be used to treat chronic myelocytic leukemia, cancer and neurodegenerative disorders. 7-bromoindirubin-3-oxime (7Bio), an indirubin derivative derived from indirubin-3-oxime, possesses inhibitory effects against cyclin-dependent kinase-5 (CDK5) and glycogen synthase kinase-3β (GSK3β), two pharmacological targets of Alzheimer's disease (AD). In this study, we have discovered that 2.3–23.3 μg/kg 7Bio effectively prevented β-amyloid (Aβ) oligomer-induced impairments of spatial cognition and recognition without affecting bodyweight and motor functions in mice. Moreover, 7Bio potently inhibited Aβ oligomer-induced expression of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α). Furthermore, 7Bio significantly prevented the decreased expression of synapsin-1 and PSD-95, biomarkers of pre-synaptic and post-synaptic proteins in Aβ oligomer-treated mice. The mean optical density (OD) with hyper-phosphorylated tau (pTau), glial fibrillary acidic protein (GFAP) and CD45 positive staining in the hippocampus of 7Bio-treated mice were significantly decreased compared to those of Aβ oligomer-treated mice. In addition, Western blotting analysis showed that 7Bio attenuated Aβ oligomer-decreased expression of pSer9-GSK3β. Those results suggested that 7Bio could potently inhibit Aβ oligomer-induced neuroinflammation, synaptic impairments, tau hyper-phosphorylation, and activation of astrocytes and microglia, which may contribute to the neuroprotective effects of 7Bio. Based on these findings, we expected that 7Bio might be developed as a novel anti-AD lead compound.

Effects of lactulose and silymarin on liver enzymes in cirrhotic rats

Silymarin, a mixture of antihepatotoxic flavonolignans used in the treatment of liver diseases, and lactulose, a nonabsorbable synthetic disaccharide, were investigated to analyze their probable synergic and healing effects in a hepatic cirrhotic rat model. Liver damage was induced by the administration and subsequent withdrawal of thioacetamide. The significant decrease in liver enzymes and malondialdehyde levels confirmed the curative effects of silymarin and lactulose. In the silymarin + lactulose group, liver enzyme and malondialdehyde levels were significantly reduced compared with those in the thioacetamide group. All treatments led to liver regeneration and triggered enhanced regeneration. Silymarin and lactulose alone or in combination have potent curative effects and reduce thioacetamide-induced liver damage.

Mesenchymal stem cell-conditioned medium prevents radiation-induced liver injury by inhibiting inflammation and protecting sinusoidal endothelial cells

Current management of radiation-induced liver injury is limited. Sinusoidal endothelial cell (SEC) apoptosis and inflammation are considered to be initiating events in hepatic damage. We hypothesized that mesenchymal stem cells (MSCs) possess anti-apoptotic and anti-inflammatory actions during hepatic irradiation, acting via paracrine mechanisms. This study aims to examine whether MSC-derived bioactive components are protective against radiation-induced liver injury in rats. MSC-conditioned medium (MSC-CM) was generated from rat bone marrow-derived MSCs. The effect of MSC-CM on the viability of irradiated SECs was examined by flow cytometric analysis. Activation of the Akt and ERK pathways was analyzed by western blot. MSC-CM was also delivered to Sprague-Dawley rats immediately before receiving liver irradiation, followed by testing for pathological features, changes in serum hyaluronic acid, ALT, and inflammatory cytokine levels, and liver cell apoptosis. MSC-CM enhanced the viability of irradiated SECs in vitro and induced Akt and ERK phosphorylation in these cells. Infusion of MSC-CM immediately before liver irradiation provided a significant anti-apoptotic effect on SECs and improved the histopathological features of injury in the irradiated liver. MSC-CM also reduced the secretion and expression of inflammatory cytokines and increased the expression of anti-inflammatory cytokines. MSC-derived bioactive components could be a novel therapeutic approach for treating radiation-induced liver injury.

The effects and possible mechanisms of puerarin to treat endometriosis model rats

Objective. To explore the effects of puerarin to treat endometriosis (EMT) model rats and the possible regulatory mechanisms. Methods. EMT model rats were surgically induced by autotransplantion of endometrial tissues. The appropriate dosage of puerarin to treat EMT model rats was determined by observing the pathologic morphology of ectopic endometrial tissues and by detecting the levels of estradiol (E2) and prostaglandin E2 (PGE2) of both serum and ectopic endometrial tissues. The related genes and proteins of ectopic endometrial tissues were analyzed by Real-time PCR and immunohistochemistry (IHC) to explore the possible mechanisms. Results. Puerarin could reduce the levels of E2 and PGE2 and prevent the growth of ectopic endometrium tissues by inhibiting the expression of aromatase cytochrome P450 (p450arom) and cyclooxygenase-2 (cox-2); puerarin could adjust the anabolism of E2 by upregulating the expression of 17β-hydroxysteroid-2 (17β-hsd-2) and downregulating the expression of 17β-hydroxysteroid-1 (17β-hsd-1) of the ectopic endometrium tissues; puerarin could increase the expression of ERβ and improve the inflammatory microenvironment of EMT model rats. Conclusions. Our data suggest that puerarin has a therapeutic effect on EMT model rats and could be a potential therapeutic agent for the treatment of EMT in clinic.

Transcriptional profiling and co-expression network analysis identifies potential biomarkers to differentiate chronic hepatitis B and the caused cirrhosis

Liver cirrhosis is one of the most common non-neoplastic causes of mortality worldwide. Chronic hepatitis B (CHB) is a major cause of liver cirrhosis in China. To find biomarkers for the diagnosis of CHB caused cirrhosis (HBC), we examined the transcriptional profiling of CHB and HBC. The leukocyte samples of CHB (n = 5) and HBC (n = 5) were analyzed by microarray. The results showed that 2128 mapped genes were differentially expressed between CHB and HBC (fold change ≥ 2.0, p < 0.05). Gene ontology (GO) analysis indicated that these 2128 differentially expressed genes (DEGs) were enriched for immune response and cell formation functions mostly. Moreover, co-expression networks using the k-core algorithm were established to determine the core genes, which may play important roles in the progression of CHB to HBC. There were markedly different gene co-expression patterns in CHB and HBC. We validated the five core genes, CASP1, TGFBI, IFI30, HLA-DMA and PAG1 in CHB (n = 60) and HBC (n = 60) by quantitative RT-PCR. The expression of the five genes were consistent with microarray, and there were statistically significant co-expression patterns of TGFβ1, PAG1 and HLA-DMA mRNA (Pearson correlation coefficient >0.6). Furthermore, we constructed an mRNA panel of TGFBI, IFI30, HLA-DMA and PAG1 (TIPH HBCtest) by means of a logistic regression model, and evaluated the TIPH HBCtest for HBC diagnosis by area under the receiver operating characteristic curve (AUC) analysis, which showed a higher accuracy (AUC = 0.903). This study suggested that there are particular transcriptional profiles, gene co-expression patterns and core genes in CHB and HBC. The TIPH HBC test may be useful in the diagnosis of HBC from CHB.

Cytokine expression in spleen affects progression of liver cirrhosis through liver-spleen cross-talk

AIM

It is unclear whether the spleen affects the progression of liver cirrhosis (LC) through "liver-spleen cross-talk". Transforming growth factor-β1 (TGF-β1) is reported to be the most potent cytokine of liver fibrosis, and interleukin-6 (IL-6) is an important factor of liver regeneration. In this study, we investigated the expression of cytokines in the spleens of LC patients in order to attempt to prove the existence of liver-spleen cross-talk.

METHODS

The study enrolled 22 patients who underwent splenectomy at our institute between 2004 and 2010. TGF-β1 expression in the resected spleen was measured using immunohistochemical staining. Two-color immunofluorescent staining for CD68 and TGF-β1 in the spleen was performed to detect sources of TGF-β1. IL-6 expression in the spleen was measured by reverse transcription polymerase chain reaction.

RESULTS

TGF-β1 expression was significantly higher in the spleens of LC patients than in those of patients with normal livers (P < 0.05). Coexpression of CD68 and TGF-β1 was confirmed. The expression of IL-6 in the spleens of LC patients was significantly lower than that in patients with normal livers (P < 0.05).

CONCLUSION

TGF-β1 produced by macrophages and cytokines such as IL-6 could affect the progression of liver fibrosis and regeneration in patients with LC via liver-spleen cross-talk.

Combined effects of an antioxidant and caspase inhibitor on the reversal of hepatic fibrosis in rats

We sought to determine the hepatic fibrosis-reversal effects upon simultaneous administration of lithospermate B (LAB), an anti-oxidant, and nivocasan, a caspase inhibitor, to rats compared with each compound alone. Liver fibrosis was induced in Sprague-Dawley rats by thioacetamide (TAA). Rats were treated with TAA and then given LAB and (or) nivocasan. Fibrotic areas were evaluated quantitatively by computerized morphometry. Apoptosis was assessed using a TUNEL assay, and immunohistochemical staining for malondialdehyde (MDA) and 4-hydroxy-2-nonenal (4HNE) was performed to assess oxidative stress levels. Real-time quantitative PCR was used to quantify expression of fibrosis-related genes. The degree of hepatic fibrosis was significantly reduced in rats treated with LAB and nivocasan compared to either treatment alone (P < 0.001). Treatment with each compound significantly decreased expression of fibrosis-related genes, such as type I collagen α1 (col1α1), α-SMA and TGF-β1 (P < 0.05). Co-treatment with LAB and nivocasan further reduced col1α1 expression compared to treatment with either compound. A TUNEL assay revealed that hepatocyte apoptosis was significantly decreased in the group treated with nivocasan compared to other groups (P < 0.01). Immunohistochemistry showed a decrease in MDA and 4HNE, reflecting amelioration of oxidative stress, when LAB or LAB+nivocasan was administered compared to nivocasan alone (P < 0.01). Nivocasan was found to inhibit caspase-1, -3, -7, -9 and gliotoxin-induced death of rat-derived hepatic stellate cells was inhibited by nivocasan administration without overexpression of α-SMA.

CONCLUSIONS

Co-incidental administration of LAB and nivocasan suppressed oxidative stress and apoptosis, resulting in enhanced reversal of hepatic fibrosis in rat.

Therapeutic effect of collagenase Ⅱ against rat liver cirrhosis

AIM: To explore the therapeutic effect of an adenovirus-HBV chimeric vector expressing collagenase Ⅱ against cirrhosis in a rat model.

METHODS: Rat liver cirrhosis was induced with 0.03% thioacetamide in drinking water for 16 wk. Ad-CH-tMMP8 and Ad-C-MMP8 were constructed using an adenovirus shuttle plasmid and a HBV chimeric vector expressing truncated and full-length collagenase Ⅱ gene. Ad-CH-RFP2 expressing red fluorescent protein was used as a negative control. Liver cirrhosis rats were injected with the three plasmids through the tail vein.

RESULTS: Compared with the model group and negative control group, fibrosis was dramatically attenuated four weeks after the infection. HE staining and picric acid-Sirius red staining showed that hepatocyte steatosis, necrosis and inflammation were significantly milder in the treatment group, along with hepatocyte proliferation, recovery of hepatic lobule structure, and diminished content of HYP (28.97 µg/g ± 2.36 µg/g vs 17.04 µg/g ± 0.61 µg/g, 17.62 µg/g ± 1.30 µg/g, P < 0.05), whereas the fibrosis in Ad-CH-RFP2-treated rats persisted.

CONCLUSION: Adenovirus-HBV chimeric vector expressing collagenase Ⅱ effectively reduces the degree of liver fibrosis in rats.

Sesamin ameliorates arterial dysfunction in spontaneously hypertensive rats via downregulation of NADPH oxidase subunits and upregulation of eNOS expression

AIM

Sesamin is one of the major lignans in sesame seeds with antihyperlipidemic, antioxidative and antihypertensive activities. The aim of this study was to examine the effects of sesamin on arterial function in spontaneously hypertensive rats (SHRs).

METHODS

SHRs were orally administered sesamin (40, 80 and 160 mg·kg(-1)·d(-1)) for 16 weeks. After the rats were killed, thoracic aortas were dissected out. The vasorelaxation responses of aortic rings to ACh and nitroprusside were measured. The expression of eNOS and NADPH oxidase subunits p47(phox) and p22(phox) in aortas were detected using Western blotting and immunohistochemistry. Aortic nitrotyrosine was measured with ELISA. The total antioxidant capacity (T-AOC) and MDA levels in aortas were also determined.

RESULTS

The aortic rings of SHRs showed significantly smaller ACh-induced and nitroprusside-induced relaxation than those of control rats. Treatment of SHRs with sesamin increased both the endothelium-dependent and endothelium-independent relaxation of aortic rings in a dose-dependent manner. In aortas of SHRs, the level of T-AOC and the expression of nitrotyrosine, p22(phox) and p47(phox) proteins were markedly increased, while the level of MDA and the expression of eNOS protein were significantly decreased. Treatment of SHRs with sesamin dose-dependently reversed these biochemical and molecular abnormalities in aortas.

CONCLUSION

Long-term treatment with sesamin improves arterial function in SHR through the upregulation of eNOS expression and downregulation of p22(phox) and p47(phox) expression.

Identification of cyclin B1 and Sec62 as biomarkers for recurrence in patients with HBV-related hepatocellular carcinoma after surgical resection

Background

Hepatocellular carcinoma (HCC) is the fifth most common cancer worldwide. Frequent tumor recurrence after surgery is related to its poor prognosis. Although gene expression signatures have been associated with outcome, the molecular basis of HCC recurrence is not fully understood, and there is no method to predict recurrence using peripheral blood mononuclear cells (PBMCs), which can be easily obtained for recurrence prediction in the clinical setting.

Methods

According to the microarray analysis results, we constructed a co-expression network using the k-core algorithm to determine which genes play pivotal roles in the recurrence of HCC associated with the hepatitis B virus (HBV) infection. Furthermore, we evaluated the mRNA and protein expressions in the PBMCs from 80 patients with or without recurrence and 30 healthy subjects. The stability of the signatures was determined in HCC tissues from the same 80 patients. Data analysis included ROC analysis, correlation analysis, log-lank tests, and Cox modeling to identify independent predictors of tumor recurrence.

Results

The tumor-associated proteins cyclin B1, Sec62, and Birc3 were highly expressed in a subset of samples of recurrent HCC; cyclin B1, Sec62, and Birc3 positivity was observed in 80%, 65.7%, and 54.2% of the samples, respectively. The Kaplan-Meier analysis revealed that high expression levels of these proteins was associated with significantly reduced recurrence-free survival. Cox proportional hazards model analysis revealed that cyclin B1 (hazard ratio [HR], 4.762; p = 0.002) and Sec62 (HR, 2.674; p = 0.018) were independent predictors of HCC recurrence.

Conclusion

These results revealed that cyclin B1 and Sec62 may be candidate biomarkers and potential therapeutic targets for HBV-related HCC recurrence after surgery.

Transforming growth factor-α attenuates hepatic fibrosis: possible involvement of matrix metalloproteinase-1

BACKGROUND

The effect of transforming growth factor (TGF)-α on fibrosis varies between cell types and the role of TGF-α in hepatic fibrosis has not been fully elucidated.

METHODS

We examined the effect of TGF-α on hepatic fibrosis using TGF-α-expressing transgenic mice fed a methionine- and choline-deficient (MCD) diet and human hepatic stellate cells (HSCs) line LX-2, rat and human primary HSCs.

RESULTS

Although the expression levels of the tissue inhibitor of metalloproteinases-1 and α1(I) collagen mRNA were unchanged, feeding the TGF-α transgenic mice the MCD diet resulted in greater expression of the murine functional analogue of matrix metalloproteinase-1 (MMP-1), MMP-13 mRNA and protein and attenuated hepatic fibrosis compared with wild-type mice. TGF-α overexpression did not affect the extent of the steatosis, oxidative stress and hepatic inflammation in the MCD diet-fed mice. The effect of TGF-α on the fibrogenic and anti-fibrogenic gene expressions varied between cell types in vitro. TGF-α increased MMP-1 mRNA expressions that were completely blocked by gefitinib in LX-2 cells. The extracellular signal-regulated kinase (ERK) 1/2, c-Jun N-terminal kinase and p38 pathways were involved in MMP-1 mRNA expression in LX-2 cells. Although TGF-α increased the phosphorylation of p38, the p38 inhibitor activated the RAS-ERK pathway and increased TGF-α-induced MMP-1 mRNA expression, which suggested that there may be a crosstalk between the RAS-ERK and the p38 pathways in LX-2 cells.

CONCLUSIONS

The TGF-α may attenuate hepatic fibrosis in part because of upregulation of the expression of MMP-1. The balance between fibrogenic and anti-fibrogenic gene expression and between the activity of the RAS-ERK and the p38 pathways may be crucial for the fibrotic process.

Hepatic regeneration after sublethal partial liver irradiation in cirrhotic rats

Our previous animal study had demonstrated that partial liver irradiation (IR) could stimulate regeneration in the protected liver, which supported the measurements adopted in radiotherapy planning for hepatocellular carcinoma. The purpose of this present study is to investigate whether cirrhotic liver repopulation could be triggered by partial liver IR. The cirrhosis was induced by thioacetamide (TAA) in rats. After cirrhosis establishment, TAA was withdrawn. In Experiment 1, only right-half liver was irradiated with single doses of 5 Gy, 10 Gy and 15 Gy, respectively. In Experiment 2, right-half liver was irradiated to 15 Gy, and the left-half to 2.5 Gy, 5 Gy and 7.5 Gy, respectively. The regeneration endpoints, including liver index (LI); mitotic index (MI); liver proliferation index (LPI); PCNA-labeling index (PCNA-LI); serum HGF, VEGF, TGF-α and IL-6, were evaluated on 0 day, 30-day, 60-day, 90-day, 120-day and 150-day after IR. Serum and in situ TGF-β1 were also measured. In both experimental groups, the IR injuries were sublethal, inducing no more than 9% animal deaths. Upon TAA withdrawal, hepatic regeneration decelerated in the controls. In Experiment 1 except for LI, all other regeneration parameters were significantly higher than those in controls for both right-half and left-half livers. In Experiment 2 all regeneration parameters were also higher compared with those in controls for both half livers. Serum HGF and VEGF were increased compared with that of controls. Both unirradiated and low dose-irradiated cirrhotic liver were able to regenerate triggered by sublethal partial liver IR and higher doses and IR to both halves liver triggered a more enhanced regeneration.

Caffeine does not enhance radiosensitivity of normal liver tissue in vivo

The aim of this study was to determine whether caffeine enhanced radiosensitivity of normal liver tissue in a rat radiation-induced liver disease model. Buffalo rat McA-RH7777 hepatocellular cancer cells and BRL3A normal liver cells were irradiated, and cell cycle distribution and apoptosis rates were analyzed. A rat model of radiation-induced liver disease was established, rats were randomized into four groups: control; caffeine alone; irradiation (IR) alone; and caffeine plus IR (Caff + IR) group. Apoptosis rates in normal rat liver tissue after IR were evaluated by TUNEL staining and caspase-3 Western blot. Transaminase activity was measured and histopathological examination was done after IR. Caffeine abrogated IR-induced G2 phase arrest (Caff + IR vs. IR: 40.9 ± 4.0 vs. 60.7 ± 5.5%, at 12 h after IR) and increased apoptosis rates (Caff + IR vs. IR: 56.1 ± 6.8 vs. 35.5 ± 4.0%, at 72 h after IR) in McA-RH7777 cells, but did not affect IR-induced G2 phase arrest and apoptosis rates at any time point after IR in BRL3A cells. Caffeine did not enhance apoptosis, transaminase activity, or histopathological injury of normal rat liver tissue at any time points after IR. This study suggests that caffeine might not enhance radiosensitivity of normal liver tissue in vivo. In an earlier study, we reported that caffeine enhanced radiosensitivity of human hepatocellular cancer in a nude mice model. Together, these results offer feasibility of clinical application.