Carriage of the PNPLA3 rs738409 C >G polymorphism confers an increased risk of non-alcoholic fatty liver disease associated hepatocellular carcinoma

BACKGROUND & AIMS

Subtle inter-patient genetic variation and environmental factors combine to determine disease progression in non-alcoholic fatty liver disease (NAFLD). Carriage of the PNPLA3 rs738409 c.444C >G minor allele (encoding the I148M variant) has been robustly associated with advanced NAFLD. Although most hepatocellular carcinoma (HCC) is related to chronic viral hepatitis or alcoholic liver disease, the incidence of NAFLD-related HCC is increasing. We examined whether rs738409 C >G was associated with HCC-risk in patients with NAFLD.

METHODS

PNPLA3 rs738409 genotype was determined by allelic discrimination in 100 European Caucasians with NAFLD-related HCC and 275 controls with histologically characterised NAFLD.

RESULTS

Genotype frequencies were significantly different between NAFLD-HCC cases (CC=28, CG=43, GG=29) and NAFLD-controls (CC=125, CG=117, GG=33) (p=0.0001). In multivariate analysis adjusted for age, gender, diabetes, BMI, and presence of cirrhosis, carriage of each copy of the rs738409 minor (G) allele conferred an additive risk for HCC (adjusted OR 2.26 [95% CI 1.23-4.14], p=0.0082), with GG homozygotes exhibiting a 5-fold [1.47-17.29], p=0.01 increased risk over CC. When compared to the UK general population (1958 British Birth Cohort, n=1476), the risk-effect was more pronounced (GC vs. CC: unadjusted OR 2.52 [1.55-4.10], p=0.0002; GG vs. CC: OR 12.19 [6.89-21.58], p<0.0001).

CONCLUSIONS

Carriage of the PNPLA3 rs738409 C >G polymorphism is not only associated with greater risk of progressive steatohepatitis and fibrosis but also of HCC. If validated, these findings suggest that PNPLA3 genotyping has the potential to contribute to multi-factorial patient-risk stratification, identifying those to whom HCC surveillance may be targeted.

TGF-β signaling in myeloid cells is required for tumor metastasis

TGF-β is overexpressed in advanced human cancers. It correlates with metastasis and poor prognosis. However, TGF-β functions as both a tumor suppressor and a tumor promoter. Here, we report for the first time that genetic deletion of Tgfbr2 specifically in myeloid cells (Tgfbr2(MyeKO)) significantly inhibited tumor metastasis. Reconstitution of tumor-bearing mice with Tgfbr2(MyeKO) bone marrow recapitulated the inhibited metastasis phenotype. This effect is mediated through decreased production of type II cytokines, TGF-β1, arginase 1, and inducible nitric oxide synthase, which promoted IFN-γ production and improved systemic immunity. Depletion of CD8 T cells diminished the metastasis defect in the Tgfbr2(MyeKO) mice. Consistent with animal studies, myeloid cells from patients with advanced-stage cancer showed increased TGF-β receptor II expression. Our studies show that myeloid-specific TGF-β signaling is an essential component of the metastasis-promoting puzzle of TGF-β. This is in contrast to the previously reported tumor-suppressing phenotypes in fibroblasts, epithelial cells, and T cells.

Preclinical therapeutic response of residual metastatic disease is distinct from its primary tumor of origin

Cancer-related deaths are caused principally by recurrence and metastasis arising from residual disease, whose therapeutic responses has been suggested to be substantially different from primary tumors. However, experimental animal models designed for evaluating the therapeutic responses of residual disease are mostly lacking. To overcome this deficiency, we have developed a preclinical model that recapitulates the progression for advanced nonsmall cell lung cancer (NSCLC). An archived Lewis lung carcinoma mouse tumor, propagated only through serial in vivo transplantation and never adapted to cell culture, was stably labeled using lentivirus-encoded biomarkers, consistently expressed through an RNA polymerase II promoter. Labeled tumors were inoculated into syngeneic immunocompetent mice to ensure superior tumor-host interactions. Primary tumors were resected on reaching a predetermined size, followed by treatment in a setting akin to postsurgical first-line adjuvant chemotherapy and routine imaging to monitor the progression of pulmonary metastasis. We discovered that efficacious treatment, instead of reducing disease growth rates, significantly prolonged disease-free survival and overall survival. As in the clinic, cisplatin-based regimes were more effective in this model. However, the response of metastases to specific agents could not be predicted from, and often opposed, their effects on subcutaneous "primary" tumors, possibly due to their distinct growth kinetics and host interactions. We here introduce a clinically relevant model of residual metastatic disease that may more accurately predict the therapeutic response of recurrent, metastatic disease.

Abstract 1640: Notch pathway mediates post-treatment repopulation of lung squamous cell carcinoma cells

Conventional adjuvant therapies, such as chemotherapy and radiotherapy, usually take intermittent schedule, allowing the recovery of the normal tissues. However, during the recovery period, tumors may resume growth to replenish the lost cells. This phenomenon, known as repopulation, is an important mechanism to mediate post-treatment recurrence. In this study, we examined murine Lewis Lung Carcinoma (LLC) with a panel of subtype markers of non-small cell lung cancer (NSCLC), and characterized it as a murine lung squamous cell carcinoma (SCC), one of the major NSCLC subtypes. To recapitulate post-treatment repopulation, LLC cells were treated with the first-line NSCLC chemotherapeutic agent, paclitaxel, at IC50 dose for 24 hours, and allowed to recover in normal culture medium. Expression of genes involved in Notch pathway and markers of airway epithelial stem cell (basal cell) in LLC cells are upregulated during the recovery phase instead of treated period. Notch pathway inhibitor, DAPT, has no significant effect on growth of LLC cells as single agent or in combination with paclitaxel. However, sequential treatment of paclitaxel for 24 hours followed by DAPT for another 24 hours delays growth of LLC cells during recovery phase, suggesting that Notch pathway mediates the post-treatment repopulation. Moreover, using different labeling markers to track cell growth, we found paclitaxel-treated LLC cells in recovery phase can stimulate the growth of healthy LLC cells in co-culture, while conditioned medium from the culture of treated cells had no significant effect. These results implied that direct contact between damaged and healthy cells is required for repopulation, thus cell-surface Notch ligand such as Jagged-1 may be involved in this mechanism. Here we suggested that treatment of Notch pathway inhibitor following chemotherapy may prevent post-treatment recurrence of lung SCC.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1640. doi:10.1158/1538-7445.AM2011-1640

Abstract A9: Preclinical modeling of responses and resistance of residual metastatic disease to adjuvant chemotherapy

The questionable predictive power of available preclinical models is explained in part by their failure to adequately replicate the clinical setting. Prevailing human xenograft models do not consider advanced disease, require the use of immunocompromised mice that reconstitute aberrant tumor-host interactions, and employ delayed tumor growth as an endpoint, which has limited clinical relevance. To overcome these deficiencies, we have developed a rapid preclinical model of spontaneous metastasis that more accurately recapitulates clinical procedures for advanced non-small cell lung cancer patients. Lewis Lung Carcinoma tumor tissue that was never adapted to cell culture was stably labeled using lentivirus-encoding bioimaging markers, inoculated into syngeneic C57BL/6 mice, and resected upon reaching a predetermined size. Mice were then treated in a setting akin to post-surgical, first-line adjuvant chemotherapy using cisplatin, paclitaxel and/or antiangiogenic agents. As in the clinic, these drugs were most effective against progression in combination. However, the response of metastases to agents could not be predicted from, and often opposed, their effects on subcutaneous tumors. Time to macrometastatic onset, instead of growth, correlated with mouse survival. Moreover, the most effective adjuvant chemotherapy did not inhibit growth, but rather extended the equivalent of clinical dormancy. These results indicate that metastatic disease is driven by micrometastatic to macrometastatic transition, and resistance to therapies is caused by the failure to maintain clinical dormancy. Identification of the mechanisms involved in these processes will provide new targets of anti-cancer therapies and biomarkers for monitoring therapeutic efficacy. We demonstrate the inadequacies of current preclinical models, and introduce a paradigm for a more clinically relevant model that may more accurately predict therapeutic response in late-stage cancer patients.

Citation Information: Clin Cancer Res 2010;16(7 Suppl):A9

Genetic variants regulating insulin receptor signalling are associated with the severity of liver damage in patients with non-alcoholic fatty liver disease

BACKGROUND/AIMS

The aim of this study was to assess the effect of functional ENPP1(ectoenzyme nucleotide pyrophosphate phosphodiesterase 1)/PC-1 (plasma cell antigen-1) and IRS-1 (insulin receptor substrate-1) polymorphisms influencing insulin receptor activity on liver damage in non-alcoholic fatty liver disease (NAFLD), the hepatic manifestation of the metabolic syndrome, whose progression is associated with the severity of insulin resistance.

PATIENTS AND METHODS

702 patients with biopsy-proven NAFLD from Italy and the UK, and 310 healthy controls. The Lys121Gln ENPP1/PC-1 and the Gly972Arg IRS-1 polymorphisms were evaluated by restriction analysis. Fibrosis was evaluated according to Kleiner. Insulin signalling activity was evaluated by measuring phosphoAKT levels by western blotting in a subset of obese non-diabetic patients.

RESULTS

The ENPP1 121Gln and IRS-1 972Arg polymorphisms were detected in 28.7% and 18.1% of patients and associated with increased body weight/dyslipidaemia and diabetes risk, respectively. The ENPP1 121Gln allele was significantly associated with increased prevalence of fibrosis stage >1 and >2, which was higher in subjects also positive for the 972Arg IRS-1 polymorphism. At multivariate analysis, the presence of the ENPP1 121Gln and IRS-1 972Arg polymorphisms was independently associated with fibrosis >1 (OR 1.55, 95% CI 1.24 to 1.97; and OR 1.57, 95% CI 1.12 to 2.23, respectively). Both polymorphisms were associated with a marked reduction of approximately 70% of AKT activation status, reflecting insulin resistance and disease severity, in obese patients with NAFLD.

CONCLUSIONS

The ENPP1 121Gln and IRS-1 972Arg polymorphisms affecting insulin receptor activity predispose to liver damage and decrease hepatic insulin signalling in patients with NAFLD. Defective insulin signalling may play a causal role in the progression of liver damage in NAFLD.

Abnormal serum alanine aminotransferase levels are associated with impaired insulin sensitivity in young women with polycystic ovary syndrome

BACKGROUND AND AIM

Non-alcoholic fatty liver disease (NAFLD) and polycystic ovary syndrome (PCOS) are both associated with insulin resistance.We assessed whether NAFLD is associated with impaired insulin sensitivity in PCOS women independently of age and total adiposity.

SUBJECTS AND METHODS

We enrolled 14 young PCOS women with NAFLD, 14 women with PCOS alone and 14 healthy controls, who were matched for age, body mass index, and total body fat (by bio-impedance analyzer). NAFLD was diagnosed by the surrogate measure of abnormal serum alanine aminotransferase (ALT) concentrations (defined as ALT>19 U/l) after excluding other secondary causes of liver disease (alcohol, virus, and medications). Insulin sensitivity was measured by euglycemic hyperinsulinemic clamp.

RESULTS

Insulin sensitivity was markedly decreased (p<0.001) in PCOS women with abnormal ALT levels, whereas it was similar between PCOS women with normal ALT levels andmatched healthy controls (8.3+/-2.5 vs 12.1+/-1.7 vs 13.2+/-1.8 mg/min x kg of fat-free mass, respectively). PCOS women with abnormal ALT levels also had higher plasma triglycerides and lower HDLcholesterol concentrations than those with PCOS alone. There was a strong inverse association between serum ALT levels and insulin sensitivity in the whole group of PCOS women (r=-0.59, p=0.0013).

CONCLUSIONS

Abnormal serum ALT levels, as surrogate measure of NAFLD, are closely associated with impaired insulin sensitivity in young PCOS women in a manner that is independent from the contribution of age and total adiposity. Early recognition of NAFLD by radiological imaging tests in this group of young patients is warranted.

Abnormal serum alanine aminotransferase levels are associated with impaired insulin sensitivity in young women with polycystic ovary syndrome

BACKGROUND AND AIM

Non-alcoholic fatty liver disease (NAFLD) and polycystic ovary syndrome (PCOS) are both associated with insulin resistance.We assessed whether NAFLD is associated with impaired insulin sensitivity in PCOS women independently of age and total adiposity.

SUBJECTS AND METHODS

We enrolled 14 young PCOS women with NAFLD, 14 women with PCOS alone and 14 healthy controls, who were matched for age, body mass index, and total body fat (by bio-impedance analyzer). NAFLD was diagnosed by the surrogate measure of abnormal serum alanine aminotransferase (ALT) concentrations (defined as ALT>19 U/l) after excluding other secondary causes of liver disease (alcohol, virus, and medications). Insulin sensitivity was measured by euglycemic hyperinsulinemic clamp.

RESULTS

Insulin sensitivity was markedly decreased (p<0.001) in PCOS women with abnormal ALT levels, whereas it was similar between PCOS women with normal ALT levels andmatched healthy controls (8.3+/-2.5 vs 12.1+/-1.7 vs 13.2+/-1.8 mg/min x kg of fat-free mass, respectively). PCOS women with abnormal ALT levels also had higher plasma triglycerides and lower HDLcholesterol concentrations than those with PCOS alone. There was a strong inverse association between serum ALT levels and insulin sensitivity in the whole group of PCOS women (r=-0.59, p=0.0013).

CONCLUSIONS

Abnormal serum ALT levels, as surrogate measure of NAFLD, are closely associated with impaired insulin sensitivity in young PCOS women in a manner that is independent from the contribution of age and total adiposity. Early recognition of NAFLD by radiological imaging tests in this group of young patients is warranted.

Lentivirus-mediated bifunctional cell labeling for in vivo melanoma study

Lentiviral vectors (LVs) are capable of labeling a broad spectrum of cell types, achieving stable expression of transgenes. However, for in vivo studies, the duration of marker gene expression has been highly variable. We have developed a series of LVs harboring different promoters for expressing reporter gene in mouse cells. Long-term culture and colony formation of several LV-labeled mouse melanoma cells showed that promoters derived from mammalian house-keeping genes, especially those encoding RNA polymerase II (Pol2) and ferritin (FerH), provided the highest consistency for reporter expression. For in vivo studies, primary B16BL6 mouse melanoma were infected with LVs whose luciferase-green fluorescence protein fusion gene (Luc/GFP) was driven by either Pol2 or FerH promoters. When transplanted into syngeneic C57BL/6 mice, Luc/GFP-labeled B16BL6 mouse melanoma cells can be monitored by bioluminescence imaging in vivo, and GFP-positive cells can be isolated from the tumors by fluorescence-activated cell sorter. Pol2-Luc/GFP labeling, while lower in activity, was more sustainable than FerH-Luc/GFP labeling in B16BL6 over consecutive passages into mice. We conclude that Pol-2-Luc/GFP labeling allows long-term in vivo monitoring and tumor cell isolation in immunocompetent mouse melanoma models.

Fatigue in non-alcoholic fatty liver disease (NAFLD) is significant and associates with inactivity and excessive daytime sleepiness but not with liver disease severity or insulin resistance

OBJECTIVE

To quantify fatigue in non-alcoholic fatty liver disease (NAFLD), to determine whether perceived fatigue reflects impairment of physical function and to explore potential causes.

PATIENTS AND METHODS

A cohort study was carried out on 156 consecutive patients with histologically proven NAFLD studied in two cohorts. Phase 1 determined the perceived fatigue experienced by NAFLD patients (assessed using the Fatigue Impact Scale (FIS)) in comparison with normal and liver disease controls, and the relationship to physical function (actigraphy). In phase 2, biological associations of fatigue in NAFLD were explored.

RESULTS

Fatigue was markedly higher in NAFLD patients than in controls (mean (SD) FIS 51 (38) vs 8 (12), p<0.001). NAFLD patients showed significantly lower physical activity over 6 days (7089 (2909) mean steps/day vs 8676 (2894), p = 0.02). A significant inverse correlation was seen between FIS and physical activity (r = 0.1, p = 0.02). Fatigue experienced by NAFLD patients was similar to that in primary biliary cirrhosis (n = 36) (FIS 64 (9) vs 61 (2), p = NS). No association was seen between FIS and biochemical and histological markers of liver disease severity or insulin resistance (homeostasis model assessment (HOMA)) (r < 0.005). Significant association was seen between fatigue severity and daytime somnolence (Epworth Sleepiness Scale) (r = 0.2, p < 0.001).

CONCLUSION

Fatigue is a significant problem in NAFLD, is similar in degree to that in primary biliary cirrhosis patients and is associated with impairment in physical function. Fatigue in NAFLD appears to be unrelated to either severity of underlying liver disease or insulin resistance, but is associated with significant daytime somnolence.

The Glasgow alcoholic hepatitis score identifies patients who may benefit from corticosteroids

INTRODUCTION

There is no consensus on the pharmacological treatment of alcoholic hepatitis. The Glasgow alcoholic hepatitis score (GAHS) has been shown to be more accurate than the modified Maddrey's discriminant function (mDF) in the prediction of outcome from alcoholic hepatitis. This study aimed to determine whether the GAHS was able to identify those patients who would benefit from corticosteroids.

METHODS

225 patients with an mDF greater than or equal to 32 from five hospital centres in the United Kingdom were reviewed. Patient survival relative to the GAHS and the use of corticosteroids was recorded.

RESULTS

144 patients with an mDF greater than or equal to 32 (64%) also had a GAHS greater than or equal to 9. There was no difference in survival between untreated or corticosteroid-treated patients for those with a GAHS less than 9. For patients with a GAHS greater than or equal to 9 the 28-day survival for untreated and corticosteroid-treated patients was 52% and 78% (p = 0.002), and 84-day survival was 38% and 59% (p = 0.02), respectively.

CONCLUSIONS

Among patients with an mDF greater than or equal to 32, there was no appreciable benefit from treatment with corticosteroids in patients with a GAHS less than 9. Patients with a GAHS greater than or equal to 9 have an extremely poor prognosis if they are not treated with corticosteroids, or if such treatment is contraindicated.

Non-alcoholic fatty liver disease (NAFLD) and cardiovascular disease: an open question

AIMS

To review available data concerning the basic science and epidemiological-clinical evidence for an association of NAFLD and cardiovascular disease.

DATA SYNTHESIS

Non-alcoholic fatty liver disease (NAFLD) defines alcohol-like hepatic histological lesions seen in the non-alcoholic, insulin resistant patient representing the hepatic counterpart of the metabolic syndrome. Along with insulin resistance, additional genetic, endocrine and vascular changes together with environmental stimuli--which are also involved in the pathogenesis of atherosclerosis--play a prominent role in the development and progression of NAFLD. Clinical and epidemiological studies seem to indicate that NAFLD is associated with an increased risk for cardiovascular disease but further studies are needed to confirm the available data. The mainstay of NAFLD treatment is based on the correction of the same metabolic changes that predispose to atherosclerosis.

CONCLUSIONS

Non-invasive evaluation of risk for cardiovascular events is recommended in all individuals presenting with NAFLD and conversely, the presence of NAFLD should always be looked for in subjects with features belonging to the metabolic syndrome. Further studies are needed on the mechanisms linking fatty liver and vascular diseases.

Genes or environment to determine alcoholic liver disease and non-alcoholic fatty liver disease

While the vast majority of heavy drinkers and individuals with obesity, insulin resistance, and the metabolic syndrome will have steatosis, only a minority will ever develop steatohepatitis, fibrosis, and cirrhosis. Genetic and environmental risk factors for advanced alcoholic liver disease (ALD) and non-alcoholic fatty liver disease (NAFLD) seem likely to include factors that influence the severity of steatosis and oxidative stress, the cytokine milieu, the magnitude of the immune response, and/or the severity of fibrosis. For ALD, the dose and pattern of alcohol intake, along with obesity are the most important environmental factors determining disease risk. For NAFLD, dietary saturated fat and antioxidant intake and small bowel bacterial overgrowth may play a role. Family studies and interethnic variations in susceptibility suggest that genetic factors are important in determining disease risk. For ALD, functional polymorphisms in the alcohol dehydrogenases and aldehyde dehydrogenase alcohol metabolising genes play a role in determining susceptibility in Oriental populations. No genetic associations with advanced NAFLD have been replicated in large studies. Preliminary data suggest that polymorphisms in the genes encoding microsomal triglyceride transfer protein, superoxide dismutase 2, the CD14 endotoxin receptor, TNF-alpha, transforming growth factor-beta, and angiotensinogen may be associated with steatohepatitis and/or fibrosis.

Spontaneous rupture of the hepatic artery in a patient with type 1 neurofibromatosis treated by embolization: a case report

We report the case of a 48-year-old man with neurofibromatosis presenting with sudden-onset abdominal pain, profound hypotension, and a drop in hemoglobin. CT scan demonstrated a massive hematoma within the right lobe of the liver with rupture into the peritoneal cavity. Angiography demonstrated diffuse abnormalities of the hepatic circulation with fusifom, ectatic, and stenotic segments. Acute extravasation from a peripheral branch of the right hepatic artery was identified and successfully embolized with subsequent hemodynamic stabilization of the patient. To the best of our knowledge this is the first case report of this kind in a patient with type I neurofibromatosis.

Popliteal artery branching patterns—an angiographic study

AIM

To analyse the variations in branching patterns of the popliteal artery and infrapopliteal vessels using angiography.

MATERIALS AND METHODS

Femoral angiograms of 1037 lower limbs in 568 patients were examined to assess the popliteal artery branching pattern. Variations of the infrapopliteal vessels supplying the foot were assessed in 662 limbs from the same cohort of patients.

RESULTS

Nine hundred and forty-one (90.7%) limbs had the usual branching pattern with anterior tibial artery (AT) arising first followed by the tibial-peroneal trunk (TPT), which then gives rise to the posterior tibial (PT) and peroneal (PR) arteries. Variations in popliteal branching pattern were seen in 96 (9.3%) limbs. The commonest variation is high origin of the AT in 47 (4.5%) limbs or trifurcation of the popliteal artery in 33 (3.2%) limbs with AT, PT and PR arising together with no true TPT. The course of AT with high origin either anterior or posterior to popliteus was almost equal [25 (2.4%) or 22 (2.1%) limbs, respectively]. Eleven limbs (1.1%) had high origin of PT and two (0.2%) had a high origin of the PR. Six hundred and fifty-five (99%) limbs had normal infrapopliteal vessels. Seven (1%) had hypoplasia-aplasia of the infrapopliteal vessels. Five (0.8%) limbs had a hypoplastic PT with the remaining 2 (0.2%) having either a hypoplastic-aplastic AT or hypoplasia-aplasia of both AT and PT.

CONCLUSION

Variations in the branching of the popliteal artery occur in about 10% of patients. Knowledge of these variations is important because of the potential consequences for the management of peripheral vascular disease.

Polymorphisms in the T cell regulatory gene cytotoxic T lymphocyte antigen 4 influence the rate of acute rejection after liver transplantation

BACKGROUND

The cytotoxic T lymphocyte antigen 4 (CTLA-4) gene encodes for a membrane bound (mCTLA-4) and a soluble (sCTLA-4) isoform, which are both involved in regulation of T cell function. The CTLA-4 +49A/G single nucleotide polymorphism (SNP) influences expression of mCTLA-4; +6230G/A SNP affects the production of sCTLA-4.

AIM

To examine whether these functional SNPs influence the rate of rejection after liver transplantation.

PATIENTS AND METHODS

Liver graft recipients (n = 483) were genotyped for both SNPs, and haplotypes were reconstructed. Association with rejection was tested by the log rank test using the Kaplan-Meier method with time to the first acute rejection episode as outcome. Multiple analysis of SNPs together with demographic factors was performed by Cox regression.

RESULTS

Three haplotypes were observed in the cohort: +49A/+6230A, +49A/+6230G, and +49G/+6230G. The +49A/+6230G haplotype was significantly and dose dependently associated with acute rejection (p = 0.01). Of the demographic factors tested, only underlying liver disease was significantly associated with rejection. Adjusted for underlying liver disease, each additional +49A/+6230G haplotype allele resulted in a significantly higher risk of acute rejection (risk ratio 1.34 (95% confidence interval 1.04-1.72); p = 0.02). Patients who lacked this haplotype had the lowest, carriers an intermediate, and homozygotes the highest risk of acute rejection.

CONCLUSION

The CTLA-4 +49A/+6230G haplotype, which encodes for normal mCTLA-4 expression but reduced sCTLA-4 production, is a co-dominant risk allele for acute rejection after clinical liver transplantation. This implies that even under immunosuppression, CTLA-4 is critically involved in the regulation of the human immune response to allogeneic grafts.

Co-regulation of B-Myb expression by E2F1 and EGF receptor

Epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase that is frequently over-expressed in human cancers and is associated with tumorigenesis, and increased tumor proliferation and progression. Also found in breast tumors with high levels is B-Myb, a transcription factor whose expression is activated by E2F1/3 at the late G1 phase and the level is sustained through the S phase. Recent reports suggest a casual correlation between EGFR and B-Myb expression in primary breast carcinomas. However, the mechanism for such co-expression remains un-investigated. Here, we report that EGFR is important for B-Myb expression and the underlying mechanism involves cooperated effects from EGFR and E2F1. EGF stimulation and forced expression of EGFR significantly increase B-Myb gene activity and such increase occurs in the G1 phase. EGF-induced B-Myb expression was not significantly suppressed following inhibition of PI-3K and ERK, two major EGFR downstream pathways. In contrast, we observed EGF-induced in vivo association of nuclear EGFR to the B-Myb promoter and the association is only detected at the G1/S phase and is abolished by EGFR kinase inhibitor. As EGFR lacks DNA-binding domain but contains transactivational activity and E2F1 activates B-Myb expression in the G1/S phase, we further reasoned that nuclear EGFR might cooperate with E2F1 leading to activation of B-Myb. Indeed, we found that EGFR co-immunoprecipitated with E2F1 in an EGF-dependent manner and that EGF activated in vivo binding of E2F1 to the B-Myb promoter. Consistently, forced expression of both EGFR and E2F1 in EGFR-null CHO cells greatly enhanced B-Myb promoter activity, compared to the vector control and expression of EGFR or E2F1 alone. Promoter mutagenesis studies showed that EGF-induced activation of B-Myb promoter required both E2F and EGFR target sites. In summary, our data suggest that deregulated EGFR signaling pathway facilitate tumor cell proliferation partly via EGFR interaction with E2F1 and subsequent activation of B-Myb gene expression.

Cancer-specific gene therapy

Cancer cells transcriptionally activate many genes that are important for uncontrolled proliferation and cell death. Deregulated transcriptional machinery in tumor cells usually consists of increased expression/activity of transcription factors. Ideally, cancer-specific killing can be achieved by delivering a therapeutic gene under the control of the DNA elements that can be activated by transcription factors that are overexpressed and/or constitutively activated in cancer cells. Additionally, tumor-specific translation of tumor-killing genes has been also exploited in cancer gene therapy. Based on these rationales, cancer-specific expression of a therapeutic gene has emerged as a potentially successful approach for cancer gene therapy. To achieve tumor-specific expression, cancer-specific vectors are generally composed of promoters, enhancers, and/or 5'-UTR that are responsive to tumor-specific transcription factors. A number of cancer-specific promoters have been reported, such as those of probasin, human telomerase reverse transcriptase, survivin, ceruloplasmin, HER-2, osteocalcin, and carcinoembryonic antigen. Evidences suggest that the enhancer element targeted by beta-catenin can be useful to target colon cancer cells. The 5'-UTR of the basic fibroblast growth factor-2 has been reported to provide tumor specificity. Moreover, a variety of therapeutic genes demonstrated direct antitumor effects such as those encoding proapoptotic proteins p53, E1A, p202, PEA3, BAX, Bik, and prodrug metabolizing enzymes, namely thymidine kinase and cytosine deaminase. As cancerous cells of different origins vary significantly in their genetic, transcriptional/translational, and cellular profiles, the success of a cancer gene therapy will not be promised unless it is carefully designed based on the biology of a specific tumor type. Thus, tremendous research efforts have been focused on the development of non-viral vectors that selectively target various tumors resulting in minimal toxicity in the normal tissues. Significant progresses were also made in the exploitation of various novel apoptotic, cytotoxic genes as therapeutic tools that suppress the growth of different tumors. Together, these recent advances provide rationales for future clinical testing of transcriptionally targeted non-viral vectors in cancer patients.

Relationship between the inhibition of phosphatidic acid phosphohydrolase-1 by oleate and oleoyl-CoA ester and its apparent translocation

Phosphatidic acid phosphohydrolase-1 (PAP-1) activity is reversibly inhibited by fatty acids and their acyl-CoA esters and it appears paradoxical that these effectors have been reported to increase the liver's esterification capacity by translocating the rate-limiting enzyme PAP-1 from cytosol to the endoplasmic reticulum. Therefore, we have examined the effect of oleate, oleoyl-CoA, and spermine on the activation and translocation of PAP-1 of rat liver. PAP-1 activity is directly inhibited by oleic acid and oleoyl-CoA ester in an allosteric manner, resulting in the formation of inactive PAP-1-fatty acid (or -acyl-CoA) complex, even in the absence of any subcellular structures. Such association/aggregation of PAP-1 can be easily collected by centrifugation and may explain the apparent translocation phenomenon of this enzyme to a particular structure in the presence of fatty acids or acyl-CoA esters as reported in many works. Indeed, incubation of cytosol fraction alone with oleate or oleoyl-CoA at 37 degrees C, followed by centrifugation, induces a significant increase (sevenfold) in PAP-1 activity in the pellet fraction. This displacement is accompanied by an increase in the specific activity of PAP-1 in the pellet fraction. Spermine is less effective than oleate in inducing the displacement of PAP-1 activity from cytosol to the pellet fraction in the absence of any membrane structures. This apparent translocation of PAP-1 is also promoted when homogenate fraction was incubated with oleate prior to the preparation of cytosol and microsomal fraction. Thus, many of the announced factors, including fatty acids, would promote the in vitro association/aggregation of PAP-1 enzyme rather than its translocation, and therefore, re-evaluation of the reported effects on PAP-1 translocation phenomenon is required. It is proposed that fatty acids and their esters would favour beta-oxidation over esterification by promoting the forming of inactive associated PAP-1 in situations such as starvation and metabolic stress in which there is an increased supply of fatty acids to the liver.

Analysis of factors predictive of mortality in alcoholic hepatitis and derivation and validation of the Glasgow alcoholic hepatitis score

INTRODUCTION

Alcoholic hepatitis is associated with a high short term mortality. We aimed to identify those factors associated with mortality and define a simple score which would predict outcome in our population.

METHODS

We identified 241 patients with alcoholic hepatitis. Clinical and laboratory data were recorded on the day of admission (day 1) and on days 6-9. Stepwise logistic regression was used to identify variables related to outcome at 28 days and 84 days after admission. These variables were included in the Glasgow alcoholic hepatitis score (GAHS) and its ability to predict outcome assessed. The GAHS was validated in a separate dataset of 195 patients.

RESULTS

The GAHS was derived from five variables independently associated with outcome: age (p = 0.001) and, from day 1 results, serum bilirubin (p<0.001), blood urea (p = 0.019) and, from day 6-9 results, serum bilirubin (p<0.001), prothrombin time (p = 0.002), and peripheral blood white blood cell count (p = 0.001). The GAHS on day 1 had an overall accuracy of 81% when predicting 28 day outcome. In contrast, the modified discriminant function had an overall accuracy of 49%. Similar results were found using information at 6-9 days and when predicting 84 day outcome. The accuracy of the GAHS was confirmed by the validation study of 195 patients The GAHS was equally accurate irrespective of the use of the international normalised ratio or prothrombin time ratio, or if the diagnosis of alcoholic hepatitis was biopsy proven or on the basis of clinical assessment.

CONCLUSIONS

Using variables associated with mortality we have derived and validated an accurate scoring system to assess outcome in alcoholic hepatitis. This score was able to identify patients at greatest risk of death throughout their admission.

Immune response towards lipid peroxidation products as a predictor of progression of non-alcoholic fatty liver disease to advanced fibrosis

AIMS

Factors responsible for the progression of non-alcoholic fatty liver disease (NAFLD) to more severe liver injury are poorly understood. In the present study, we investigated the association between immune reactions triggered by oxidative stress and stage of NAFLD.

METHODS

Titres of IgG against human serum albumin adducted with malondialdehyde (MDA-HSA) or arachidonic acid hydroperoxide (AAHP) and against oxidised cardiolipin (Ox-CL) were measured in 167 NAFLD patients with steatosis only (n = 79), steatohepatitis (n = 74), or steatosis plus cirrhosis (n = 14), and in 59 age and sex matched controls.

RESULTS

Circulating IgG against lipid peroxidation products was significantly higher (p<0.001) in NAFLD patients than in controls. Oxidative stress dependent immune responses were not associated with obesity, type 2 diabetes, or with serum cholesterol, ferritin, or aminotransferase levels. Titres of lipid peroxidation related antibodies were also independent of the extent of steatosis and were similarly distributed in patients with and without necroinflammation. In contrast, the same antibodies were significantly increased in patients with advanced fibrosis or cirrhosis. Logistic regression analysis confirmed that anti-MDA antibodies were independently associated with progression of NALFD and that NAFLD patients with titres of anti-MDA-HSA antibodies above the control threshold value had a threefold (relative risk 2.82 (95% confidence interval 1.35-5.90); p = 0.007) higher risk of having advanced fibrosis/cirrhosis than patients whose antibody titres were within the control range.

CONCLUSIONS

These results indicate that the presence of immune reactions triggered by oxidative stress can be an independent predictor of progression of NAFLD to advanced fibrosis.