Carolin Lackner

Complex Tumor Genomes Inferred from Single Circulating Tumor Cells by Array-CGH and Next-Generation Sequencing

Circulating tumor cells (CTC) released into blood from primary cancers and metastases reflect the current status of tumor genotypes, which are prone to changes. Here, we conducted the first comprehensive genomic profiling of CTCs using array-comparative genomic hybridization (CGH) and next-generation sequencing. We used the U.S. Food and Drug Administration-cleared CellSearch system, which detected CTCs in 21 of 37 patients (range, 1-202/7.5 mL sample) with stage IV colorectal carcinoma. In total, we were able to isolate 37 intact CTCs from six patients and identified in those multiple colorectal cancer-associated copy number changes, many of which were also present in the respective primary tumor. We then used massive parallel sequencing of a panel of 68 colorectal cancer-associated genes to compare the mutation spectrum in the primary tumors, metastases, and the corresponding CTCs from two of these patients. Mutations in known driver genes [e.g., adenomatous polyposis coli (APC), KRAS, or PIK3CA] found in the primary tumor and metastasis were also detected in corresponding CTCs. However, we also observed mutations exclusively in CTCs. To address whether these mutations were derived from a small subclone in the primary tumor or represented new variants of metastatic cells, we conducted additional deep sequencing of the primary tumor and metastasis and applied a customized statistical algorithm for analysis. We found that most mutations initially found only in CTCs were also present at subclonal level in the primary tumors and metastases from the same patient. This study paves the way to use CTCs as a liquid biopsy in patients with cancer, providing more effective options to monitor tumor genomes that are prone to change during progression, treatment, and relapse.

Comparison and validation of simple noninvasive tests for prediction of fibrosis in chronic hepatitis C

Liver biopsy is recommended before antiviral treatment, particularly for patients with hepatitis C virus (HCV) genotype 1 infection, but it may cause complications and is limited by sampling error. Several non‐invasive tests comprising routine laboratory parameters (simple fibrosis tests) have been proposed to predict fibrosis in chronic HCV. The aim of the current study was to validate and compare the diagnostic accuracies of the simple fibrosis tests, aspartate aminotransferase (AST)/alanine aminotransferase (ALT) ratio (AAR), cirrhosis discriminant score (CDS), age‐platelet (AP) index, Pohl score, AST‐to‐platelet ratio index (APRI), and platelet count per se. Staging was performed in liver biopsy specimens of 194 treatment‐naïve patients with chronic HCV according to Ishak et al. by two independent pathologists. Receiver operating characteristic curve analysis showed comparable diagnostic accuracies of CDS, AP index, APRI, and platelet count for prediction of significant fibrosis (F3‐F6) (area under the ROC curve [AUROC], 0.71, 0.74, 0.80, and 0.71, respectively; pathologist A) and for prediction of cirrhosis (F5‐F6) (AUROC, 0.91, 0.91, 0.90, and 0.89, respectively; pathologist A). Diagnostic accuracy of APRI for prediction of significant fibrosis was superior to that of AAR (P < .05). Significant fibrosis was reliably predicted by APRI ≥ 1.5 and platelet count <150 ×109/L in 24% and 22% of the patients, respectively, whereas cirrhosis was reliably excluded by APRI <2.0 and platelet count ≥ 150 ×109/L in 85% and 78% of the patients, respectively. In conclusion, simple fibrosis tests may render liver biopsy unnecessary only in a minority of patients with chronic HCV. Improved serum fibrosis markers with greater sensitivity for severe fibrosis or cirrhosis are needed. (HEPATOLOGY 2005;41:1376–1382.)

The keratin cytoskeleton in liver diseases.

The keratin intermediate filament (IF) cytoskeleton of hepatocytes has continuously gained medical relevance over the last two decades. Originally it was mainly recognized as a differentiation marker for diagnostic purposes in pathology. However, keratin IFs were soon identified as major cellular structures to be affected in a variety of chronic liver diseases, such as alcoholic and non‐alcoholic steatohepatitis (ASH, NASH), copper toxicosis, and cholestasis. Based on observations in keratin gene knock‐out mice, the insight into the functional role of keratins was extended from a mere structural role providing mechanical stability to hepatocytes, to an additional role as target and modulator of toxic stress and apoptosis. The functional relevance of keratins in human diseases has recently been underlined by the identification of mutations in keratin genes in patients with liver cirrhosis. Copyright

Oxidative damage of albumin in advanced liver disease

Albumin has a number of biological functions and the serum albumin level is related to prognosis in advanced liver disease. Oxidative stress is believed to play an important role in the pathogenesis of liver failure. The aim of the present study was to characterize oxidative modification of albumin in patients with various degrees of liver failure and to investigate implications for its binding function. Patients with liver cirrhosis (n=10), acute-on-chronic liver failure (n=8) and healthy controls (n=15) were included in the study. Three fractions of albumin were separated by HPLC according to the redox state of cysteine-34 and detected by fluorescence as well as UV absorption. Carbonyl groups were measured as a marker of oxidative modification in plasma proteins and, by western blotting, on albumin. Progressive oxidative modification of albumin was found with increasing severity of liver failure indicated by an increased content of carbonyl groups and oxidation of cysteine-34. Fluorescence properties of albumin were altered by oxidation and, in patients with acute-on-chronic liver failure, by high plasma levels of bilirubin. This alteration of albumin fluorescence by bilirubin provides evidence for a preferred binding of bilirubin to the fully reduced form of albumin.

Establishment of tumor‐specific copy number alterations from plasma DNA of patients with cancer

With the increasing number of available predictive biomarkers, clinical management of cancer is becoming increasingly reliant on the accurate serial monitoring of tumor genotypes. We tested whether tumor‐specific copy number changes can be inferred from the peripheral blood of patients with cancer. To this end, we determined the plasma DNA size distribution and the fraction of mutated plasma DNA fragments with deep sequencing and an ultrasensitive mutation‐detection method, i.e., the Beads, Emulsion, Amplification, and Magnetics (BEAMing) assay. When analyzing the plasma DNA of 32 patients with Stage IV colorectal carcinoma, we found that a subset of the patients (34.4%) had a biphasic size distribution of plasma DNA fragments that was associated with increased circulating tumor cell numbers and elevated concentration of mutated plasma DNA fragments. In these cases, we were able to establish genome‐wide tumor‐specific copy number alterations directly from plasma DNA. Thus, we could analyze the current copy number status of the tumor genome, which was in some cases many years after diagnosis of the primary tumor. An unexpected finding was that not all patients with progressive metastatic disease appear to release tumor DNA into the circulation in measurable quantities. When we analyzed plasma DNA from 35 patients with metastatic breast cancer, we made similar observations suggesting that our approach may be applicable to a variety of tumor entities. This is the first description of such a biphasic distribution in a surprisingly high proportion of cancer patients which may have important implications for tumor diagnosis and monitoring.

Effect of extracorporeal liver support by MARS and Prometheus on serum cytokines in acute-on-chronic liver failure

IntroductionCytokines are believed to play an important role in acute-on-chronic liver failure (ACLF). Extracorporeal liver support systems may exert beneficial effects in ACLF via removal of cytokines. At present, two systems are commercially available, the Molecular Adsorbent Recirculating System (MARS™) and Fractionated Plasma Separation, Adsorption and Dialysis (Prometheus™). The aim of this study was to compare the effects of MARS and Prometheus treatments on serum cytokine levels and their clearances.MethodsEight patients with ACLF underwent alternating treatments with either MARS or Prometheus in a randomized cross-over design. Thirty-four treatments (17 MARS, 17 Prometheus) were available for analysis. Serum cytokines were measured before and after each treatment, and cytokine clearance was calculated from paired arterial and venous samples and effective plasma flow one hour after the start of treatment.ResultsBaseline serum levels of interleukin (IL)-6, IL-8, IL-10, tumor necrosis factor-alpha (TNF-α), and soluble TNF-α receptor 1 were significantly elevated in patients with ACLF. Measurable plasma clearances were detected for all cytokines tested, but no significant changes in serum levels of any cytokine were found after treatments with MARS or Prometheus. In MARS treatments, IL-10 was cleared from plasma more efficiently than IL-6. Clearance of IL-10 was higher in Prometheus than in MARS treatments.ConclusionCytokines are cleared from plasma by both MARS and Prometheus, but neither system is able to change serum cytokine levels. This discrepancy is probably due to a high rate of cytokine production in patients with ACLF.

Effects of n-3 fish oil on metabolic and histological parameters in NASH: A double-blind, randomized, placebo-controlled trial

BACKGROUND & AIMS This studys aim was to assess the histological and metabolic effects of n-3 polyunsaturated fatty acids (PUFAs) vs. placebo while adjusting for the impact of age and weight change in NASH patients. (ClinicalTrials.gov: NCT00681408). METHODS Forty-one subjects with non-cirrhotic NASH were enrolled, and 34 completed the study. 17 received n-3 fish oil 3000 mg/day and 17 received placebo daily for 1 year with typical counselling on caloric intake and physical activity for all subjects. RESULTS N-3- and placebo-treated groups showed no significant difference for the primary end point of NASH activity score (NAS) reduction ⩾ 2 points without fibrosis progression after adjustment for known covariates (n-3, 4/17 (23.5%); placebo, 3/17, (17.6%), p = 0.99). Among subjects with increased or stable weight, n-3 subjects showed a larger decrease in liver fat content by MRI than placebo-treated subjects (p = 0.014 for 2nd quartile, p = 0.003 for 3rd quartile of weight change). N-3 treatment showed significant fat reduction on the paired analysis of image-assisted fat morphometry regardless of weight loss or gain. Exercise capacity remained markedly reduced in all subjects. No independent effects on markers of hepatocyte injury or insulin sensitivity indices were observed. CONCLUSION N-3 PUFAs at 3000 mg/day for one year did not lead to an improvement in the primary outcome of histological activity in NASH patients (⩾ 2 point NAS reduction). N-3 led to reduced liver fat by multiple measures. Other metabolic effects were not seen, although no detrimental effects were apparent. Whether longer duration, higher dose, or different composition of n-3 therapy would lead to additional benefits is uncertain.

Oxidative albumin damage in chronic liver failure: Relation to albumin binding capacity, liver dysfunction and survival

BACKGROUND & AIMS Impaired binding function of albumin has been demonstrated in end-stage liver disease. This and other functional disturbances of albumin may be related to oxidative stress which is believed to play an important role in the pathogenesis of liver failure as well as sepsis. The aim of the present study was to relate oxidative modification of albumin to loss of albumin binding function in advanced chronic liver failure and in sepsis. METHODS Patients with decompensated cirrhosis or sepsis and healthy controls were investigated. Three fractions of albumin were separated by chromatography according to the redox state of cysteine-34: non-oxidized human mercaptalbumin, reversibly oxidized human non-mercaptalbumin-1, and irreversibly oxidized human non-mercaptalbumin-2 (HNA2). Binding properties of albumin site II were measured using dansylsarcosine as a ligand. RESULTS Both in cirrhotic and septic patients, fractions of oxidized albumin were increased and binding capacity for dansylsarcosine was decreased. Mass spectroscopy confirmed specific oxidation of cysteine-34. In cirrhotic patients, dansylsarcosine binding correlated strongly with liver function parameters and moderately with HNA2. Baseline levels of HNA2 accurately predicted 30-day and 90-day survival in cirrhotic patients and this was confirmed in an external validation cohort. CONCLUSIONS Our results suggest that oxidative damage impairs binding properties of albumin. In advanced liver disease, reduced binding capacity of albumin site II is mainly related to impaired liver function. The plasma level of HNA2 is closely related to survival and may represent a novel biomarker for liver failure.

Ursodeoxycholic acid exerts farnesoid X receptor-antagonistic effects on bile acid and lipid metabolism in morbid obesity

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Prognostic relevance of tumour-associated macrophages and von Willebrand factor-positive microvessels in colorectal cancer

Tumour-associated macrophages (TAM) are involved in tumour angiogenesis and anti-tumour immune response. In colorectal cancer (CRC), an association of high microvascular density (MVD) and unfavourable prognosis has been reported by some investigators. However, heterogeneous patient groups were studied. We, therefore, analysed the correlation between TAM and MVD and the prognostic relevance of MVD, TAM and T lymphocyte infiltration for long-term survival in a homogeneous group of 70 patients with moderately differentiated cancers of the International Union Against Cancer (UICC) stages II and III, who did not receive chemotherapy. MVD was evaluated using immunohistochemistry with antibodies against CD34 and von Willebrand factor (vWF). TAM and T lymphocytes were visualised with antibodies against CD68 and CD3, respectively. Statistical analysis did not reveal a significant correlation between TAM and T lymphocyte numbers and MVD. Multivariate analysis of immunohistochemical data from all CRC patients and the subgroup of patients with UICC stage-II CRC identified TAM- and vWF-positive microvessel numbers as prognostically relevant markers. Low numbers of TAM- and high numbers of vWF-positive microvessels were associated with an unfavourable prognosis. In conclusion, TAM- and vWF-positive microvessel numbers may serve as independent prognostic markers for patients with UICC stage-II and -III CRC and may help to identify patients with an unfavourable prognosis.