PEX5 translocation into and out of peroxisomes drives matrix protein import.

Peroxisomes are ubiquitous organelles whose dysfunction causes fatal human diseases. Most peroxisomal enzymes are imported from the cytosol by the receptor PEX5, which interacts with a docking complex in the peroxisomal membrane and then returns to the cytosol after monoubiquitination by a membrane-embedded ubiquitin ligase. The mechanism by which PEX5 shuttles between cytosol and peroxisomes and releases cargo inside the lumen is unclear. Here, we use Xenopus egg extract to demonstrate that PEX5 accompanies cargo completely into the lumen, utilizing WxxxF/Y motifs near its N terminus that bind a lumenal domain of the docking complex. PEX5 recycling is initiated by an amphipathic helix that binds to the lumenal side of the ubiquitin ligase. The N terminus then emerges in the cytosol for monoubiquitination. Finally, PEX5 is extracted from the lumen, resulting in the unfolding of the receptor and cargo release. Our results reveal the unique mechanism by which PEX5 ferries proteins into peroxisomes.

High farnesoid X receptor expression predicts favorable clinical outcomes in PD­L1low/negative non­small cell lung cancer patients receiving anti­PD­1­based chemo­immunotherapy.

Anti­programmed death­1 (PD­1)/programmed death­ligand 1 (PD­L1)­directed immunotherapy has revolutionized the treatment of advanced non­small cell lung cancer (NSCLC). However, predictive biomarkers are still lacking, particularly in identifying PD­L1low/negative patients who will benefit from immunotherapy. It was previously reported that farnesoid X receptor (FXR) downregulated PD­L1 expression in NSCLC, and that FXRhighPD­L1low mouse Lewis lung carcinoma tumors showed an increased susceptibility to PD­1 blockade compared with mock tumors. At present, whether the FXRhighPD­L1low phenotype predicts clinical response to immunotherapy in patients with NSCLC remains unclear. Herein, a retrospective study was conducted to examine the expression levels of FXR, PD­L1 and CD8+ T cells by immunohistochemistry in a cohort of 149 patients with NSCLC receiving anti­PD­1­based chemo­immunotherapy. The results revealed that high FXR and PD­L1 expression levels were associated with higher objective response rates (ORR) in all patients. High PD­L1 expression also indicated superior progression­free survival (PFS). Interestingly, an inverse correlation was identified between FXR and PD­L1 expression in specimens with NSCLC. Subgroup analysis revealed that high FXR expression was associated with a higher ORR, as well as longer PFS and overall survival (OS) in PD­L1low patients. Cox multivariate analysis revealed that high FXR expression was an independent predictor for PFS and OS in PD­L1low patients. Tumor microenvironment evaluation revealed a statistically significant decrease of infiltrating CD8+ T cells in FXRhigh specimens with NSCLC. Overall, the present study proposed an FXRhighPD­L1low signature as a candidate predictor of response to anti­PD­1­based chemo­immunotherapy in PD­L1low/negative patients with NSCLC, providing evidence that could be used to broaden the patients benefitting from immunotherapy.

Immune related endonucleases and GTPases are not associated with tumor response in patients with advanced non-small cell lung cancer treated with checkpoint inhibitors.

Immune related endonucleases have recently been described as potential therapeutic targets and predictors of response to treatment with immune checkpoint inhibitors (ICI). The aim is to evaluate the association between the expression of 5 biomarkers involved in the immune response (CD73, CD39, VISTA, Arl4d and Cytohesin-3) in parallel with the more common ICI-predictive markers, PD-L1 expression and Tumor Mutation Burden (TMB) with response to ICI therapy in an advanced non-small cell lung cancer (NSCLC) cohort. METHODS: Patients with advanced NSCLC treated with ICI single agent were divided into responders and non-responders according to RECIST v1.1 and duration of response (DOR) criteria. Immunohistochemistry was performed on pretreatment tumor tissue samples for PD-L1, CD73, CD39, VISTA, Arl4d, and Cytohesin-3 expression. TMB was estimated with NEOplus v2 RUO (NEO New Oncology GmbH) hybrid capture next generation sequencing assay. Resistance mutations in STK11/KEAP1 and positive predictive mutations in ARID1A/POLE were also evaluated. RESULTS: Included were 56 patients who were treated with ICI single agent. The median progression-free and overall survival for the whole cohort was 3.0 (95% CI, 2.4-3.6) and 15 (95% CI, 9.7-20.2) months, respectively. The distribution of CD73 in tumor cells and CD39, VISTA, Arl4d and Cytohesin-3 expression in immune cells were not different between responders and non-responders. Also, PD-L1 and TMB were not predictive for response. The frequency of STK11, KEAP1 and ARID1A mutations was low and only observed in the non-responder group. CONCLUSION: Separate and combined expression of 5 biomarkers involved in the immune response (CD73, CD39, VISTA, Arl4d, and Cytohesin-3) was not associated with response in our cohort of advanced NSCLC patients receiving single agent ICI. To confirm our findings the analysis of independent larger cohorts is warranted.

Pathophysiology of reflux oesophagitis: role of Toll-like receptors 2 and 4 and Farnesoid X receptor.

The pathogenesis of gastroesophageal reflux disease (GERD) is not fully understood. It involves the activation of mucosal immune-mediated and inflammatory responses. Toll-like receptors (TLR) 2 and TLR4 are pattern-recognition receptors of the innate immune system; they recognize microbial and endogenous ligands. Farnesoid X receptor (FXR) is a bile acid receptor that regulates the inflammatory response. We aimed to evaluate TLR2, TLR4 and FXR expression patterns in GERD. We re-evaluated 84 oesophageal biopsy samples according to the global severity (GS) score, including 26 cases with histologically normal oesophagus, 28 with histologically mild oesophagitis and 30 with severe oesophagitis. We used immunohistochemistry and in situ hybridization to assess the expression patterns of TLR2, TLR4 and FXR in oesophageal squamous cells. Immunohistochemistry showed that nuclear and cytoplasmic TLR2 was expressed predominantly in the basal layer of normal oesophageal epithelium. In oesophagitis, TLR2 expression increased throughout the epithelium, and the superficial expression was significantly more intensive compared to normal epithelium, p <0.01. Nuclear and cytoplasmic TLR4 was expressed throughout the thickness of squamous epithelium, with no change in oesophagitis. FXR was expressed in the nuclei of squamous cells, and the intensity of the expression increased significantly in oesophagitis (p <0.05). FXR expression correlated with basal TLR2. In situ hybridization confirmed the immunohistochemical expression patterns of TLR2 and TLR4. In GERD, TLR2, but not TLR4, expression was upregulated which indicates that innate immunity is activated according to a specific pattern in GERD. FXR expression was increased in GERD and might have a regulatory connection to TLR2.

FXR in the dorsal vagal complex is sufficient and necessary for upper small intestinal microbiome-mediated changes of TCDCA to alter insulin action in rats.

OBJECTIVE: Conjugated bile acids are metabolised by upper small intestinal microbiota, and serum levels of taurine-conjugated bile acids are elevated and correlated with insulin resistance in people with type 2 diabetes. However, whether changes in taurine-conjugated bile acids are necessary for small intestinal microbiome to alter insulin action remain unknown. DESIGN: We evaluated circulating and specifically brain insulin action using the pancreatic-euglycaemic clamps in high-fat (HF) versus chow fed rats with or without upper small intestinal healthy microbiome transplant. Chemical and molecular gain/loss-of-function experiments targeting specific taurine-conjugated bile acid-induced changes of farnesoid X receptor (FXR) in the brain were performed in parallel. RESULTS: We found that short-term HF feeding increased the levels of taurochenodeoxycholic acid (TCDCA, an FXR ligand) in the upper small intestine, ileum, plasma and dorsal vagal complex (DVC) of the brain. Transplantation of upper small intestinal healthy microbiome into the upper small intestine of HF rats not only reversed the rise of TCDCA in all reported tissues but also enhanced the ability of either circulating hyperinsulinaemia or DVC insulin action to lower glucose production. Further, DVC infusion of TCDCA or FXR agonist negated the enhancement of insulin action, while genetic knockdown or chemical inhibition of FXR in the DVC of HF rats reversed insulin resistance. CONCLUSION: Our findings indicate that FXR in the DVC is sufficient and necessary for upper small intestinal microbiome-mediated changes of TCDCA to alter insulin action in rats, and highlight a previously unappreciated TCDCA-FXR axis linking gut microbiome and host insulin action.

Immunofluorescence Labeling of Nuclear Receptor Expression in Formalin-Fixed, Paraffin-Embedded Tissue.

Immunofluorescent staining (IF) uses antigen-antibody complexes tagged with fluorochromes to observe the expression of proteins within a tissue sample. Multiple groups have described optimized methods to visualize several proteins simultaneously within the same tissue section using immunofluorescence in both mouse and human FFPE tissues. Our group routinely uses an optimized protocol described here to examine nuclear receptor expression in experimental samples from conditional knockout in vivo studies.

Methodologies to monitor protein turnover at the inner nuclear membrane.

Lamin B receptor (LBR) is an inner nuclear membrane protein that associates with the nuclear lamina and harbors sterol reductase activity essential for cholesterol biosynthesis. Several LBR mutations implicated in human congenital disorders give rise to C-terminal truncations which render LBR metabolically unstable, resulting in their rapid turnover in the nucleus. These LBR variants serve as model substrates for investigating the poorly understood protein quality control pathways in the mammalian nuclear envelope (NE). Here we describe a split-GFP-based method for tagging these model substrates to enable live cell imaging and flow cytometry for the identification and characterization of NE-resident protein turnover machinery. Furthermore, we describe a facile subcellular fractionation method to isolate a soluble LBR degradation intermediate, allowing the deconvolution of the membrane extraction and proteasomal turnover steps. The combination of imaging-based and biochemical approaches described here facilitates detailed mechanistic studies to dissect protein turnover in the nuclear compartment.

Evidence for the involvement of FXR signaling in ovarian granulosa cell function.

Farnesoid X receptor (FXR) is mainly present in enterohepatic tissues and regulates cholesterol, lipid, and glucose homeostasis in coordination with target genes such as SHP and FABP6. Although FXR has been revealed to be expressed in reproductive tissues, FXR function and expression levels in the ovary remain unknown. In this study, we investigated FXR expression in mouse ovaries and its target genes in ovarian granulosa cells. In situ hybridization and immunohistochemical staining showed that FXR was mainly distributed in secondary and tertiary follicles. The agonist-induced activation of FXR in cultured granulosa cells induced the expression of SHP and FABP6, while siRNA targeting of FXR decreased CYP19a1 and HSD17b1 expression. Upon examination of the roles of SHP and FABP6 in granulosa cells, we found that SHP overexpression significantly decreased StAR, CYP11a1, and HSD3b gene expression. In addition, siRNA targeting of FABP6 decreased CYP19a1 and HSD17b1 expression, while FABP6 overexpression increased CYP19a1 expression. In conclusion, the present study demonstrates the presence of FXR signaling in the ovary and reveals that FXR signaling may have a role in function of granulosa cells.

IMP3 as a prognostic biomarker in patients with malignant peritoneal mesothelioma.

Malignant peritoneal mesothelioma (MPeM) is an incurable cancer with poor prognosis, and several biomarkers have been suggested for screening of MPeM. The aim of our study was to evaluate the prognostic significances of IMP3 and Fli-1 in MPeM. Diagnostic biopsies of 44 MPeM patients were centrally collected and were immunohistochemically analyzed for expression of IMP3, Fli-1, and Ki-67. Labeling was assessed by 2 pathologists. Complete clinical information and follow-up were obtained from patients' records. Carcinomas expressed Fli-1 in 42 (95.5%) of 44 specimens, and IMP3 in 23 (52.3%) of 44 specimens. Spearman ρ analysis revealed that Fli-1 expression was related to both histologic type and Ki-67 labeling index (Ki-67LI; r = -0.500, P < .05; r = 0.358, P < .05), and IMP3 expression was related to Ki-67LI (r = 0.401, P < .05). A Kaplan-Meier analysis and univariate Cox regression analysis showed that tumor-directed treatment, a lower peritoneal carcinomatosis index, stage I, lower Ki-67LI, and lower level of IMP3 expression had a statistically significantly positive effect on overall survival; Fli-1 did not affect overall survival in the univariate analysis (hazard ratio [HR], 1.026; P = .904). A Kaplan-Meier analysis showed the correlation between IMP3-Fli-1 and overall survival, whereas univariate and multivariate Cox regression analyses did not confirm the correlation. Cox regression analysis revealed that IMP3 expression (HR, 2.311 [95% confidence interval, 1.190-4.486]; P = .013) and no tumor-directed treatment (HR, 0.189 [95% confidence interval, 0.086-0.416]; P = .000) retained independent prognostic significance, both with negative effect on OS. IMP3, along with tumor-directed treatment protocols, is a powerful prognosticator in patients with MPeM.

Overexpression of signal sequence receptor γ predicts poor survival in patients with hepatocellular carcinoma.

SSR subunit γ (SSR3), an SSR family member, is heavily involved in cell growth and differentiation and closely associated with many tumor types. However, the role of this protein in HCC remains unknown. In this study, we used data from public databases to analyze SSR3 expression in HCC. We subjected 20 pairs of fresh-frozen tissues to quantitative real-time polymerase chain reaction to investigate SSR3 expression. We also subjected 95 formalin-fixed, paraffin-embedded HCC tissues to immunohistochemistry to detect SSR3 expression and determine the clinical significance of SSR3 expression in HCC. Bioinformatics analysis and quantitative real-time polymerase chain reaction results showed that compared with that in adjacent normal liver tissues, SSR3 was highly expressed in HCC tissues. High SSR3 expression was positively correlated with tumor size (P < .01), cancer embolus (P = .01), TNM stages (P = .02), and differentiation grades (P < .01). Kaplan-Meier and Cox proportional hazards analyses indicated that high SSR3 expression was significantly associated with poor survival in HCC patients and that SSR3 was an independent prognostic factor for overall survival in HCC patients. In conclusion, SSR3 acts as an oncogene in HCC and can therefore serve as a biomarker for the prognoses of HCC patients.

Activated-farnesoid X receptor (FXR) expressed in human sperm alters its fertilising ability.

The farnesoid X receptor alpha (FXR) is a bile acid sensor activated by binding to endogenous bile acids including chenodeoxycholic acid (CDCA). Although, FXR is expressed in male reproductive tissue, the relevance of the receptor on reproduction is scarcely known. Here, we demonstrated the FXR presence and its action on several human sperm features. Western blot and immunofluorescence assays evidenced the FXR expression in human spermatozoa and the localisation in the middle piece. CDCA increasing concentrations and GW4064, synthetic ligand of FXR, were used to study the FXR influence on sperm motility, survival, capacitation, acrosome reaction and on glucose as well as lipid metabolism. Interestingly, our data showed that increasing concentrations of CDCA negatively affected sperm parameters, while the receptor blockage by (Z)-Guggulsterone and by the anti-FXR Ab reversed the effects. Intriguingly, elevated CDCA levels increased triglyceride content, while lipase and G6PDH activities were reduced with respect to untreated samples, thus impeding the metabolic reprogramming typical of the capacitated sperm. In conclusion, in this study, we demonstrated for the first time a novel target for FXR and that the activated receptor alters the acquisition of sperm fertilising ability. We showed that sperm itself express the FXR and it is responsive to specific ligands of the receptor; therefore, bile acids influence this cell both in male and in female genital tracts. It might be hypothesized that bile acid levels could be involved in infertility with idiopathic origin as these compounds are not systematically measured in men undergoing medically assisted procreation.

Minimum datasets to establish a CAR-mediated mode of action for rodent liver tumors.

Methods for investigating the Mode of Action (MoA) for rodent liver tumors via constitutive androstane receptor (CAR) activation are outlined here, based on current scientific knowledge about CAR and feedback from regulatory agencies globally. The key events (i.e., CAR activation, altered gene expression, cell proliferation, altered foci and increased adenomas/carcinomas) can be demonstrated by measuring a combination of key events and associative events that are markers for the key events. For crop protection products, a primary dataset typically should include a short-term study in the species/strain that showed the tumor response at dose levels that bracket the tumorigenic and non-tumorigenic dose levels. The dataset may vary depending on the species and the test compound. As examples, Case Studies with nitrapyrin (in mice) and metofluthrin (in rats) are described. Based on qualitative differences between the species, the key events leading to tumors in mice or rats by this MoA are not operative in humans. In the future, newer approaches such as a CAR biomarker signature approach and/or in vitro CAR3 reporter assays for mouse, rat and human CAR may eventually be used to demonstrate a CAR MoA is operative, without the need for extensive additional studies in laboratory animals.

The poor prognosis of the primary gastric epithelioid angiosarcoma: A case report.

RATIONALE: Primary gastric epithelioid angiosarcoma is a highly aggressive endothelial cell malignancy and may pose a great diagnostic challenge. PATIENT CONCERNS: Here we describe the case of a 56-year-old man presented with melena and epigastric dull pain for 2 weeks. DIAGNOSIS: Primary gastric epithelioid angiosarcomas: the definitive diagnosis was provided by immunohistochemical analysis with endothelial markers such as cluster of differentiation 31 (CD31), ether-a-go-go-related gene (ERG), and Freund leukemia integration (FLI-1). INTERVENTIONS: After gastroscopic biopsy was performed at the bleeding fundus and the results suggested malignant tumor, radical gastrectomy was performed. OUTCOMES: Unfortunately, regional lymph node enlargement and distant metastases occurred about 1 month later. The patient did not have the opportunity to undergo chemotherapy or other treatment and died from multiple organ dysfunction syndrome. LESSONS: Primary gastric epithelioid angiosarcomas are rare tumors with a high rate of lymph nodes and peripheral organs metastasis. The strong cytokeratin expression in epithelioid angiosarcomas represents a diagnostic pitfall for pathologists. Their clinical behaviors are unpredictable and results with surgical excision alone have been disappointing. Thus, the prognosis is generally considered poor and patients seldom can survive over 1 year after diagnosis.

Monitoring ligand-dependent assembly of receptor ternary complexes in live cells by BRETFect.

There is currently an unmet need for versatile techniques to monitor the assembly and dynamics of ternary complexes in live cells. Here we describe bioluminescence resonance energy transfer with fluorescence enhancement by combined transfer (BRETFect), a high-throughput technique that enables robust spectrometric detection of ternary protein complexes based on increased energy transfer from a luciferase to a fluorescent acceptor in the presence of a fluorescent intermediate. Its unique donor-intermediate-acceptor relay system is designed so that the acceptor can receive energy either directly from the donor or indirectly via the intermediate in a combined transfer, taking advantage of the entire luciferase emission spectrum. BRETFect was used to study the ligand-dependent cofactor interaction properties of the estrogen receptors ERα and ERß, which form homo- or heterodimers whose distinctive regulatory properties are difficult to dissect using traditional methods. BRETFect uncovered the relative capacities of hetero- vs. homodimers to recruit receptor-specific cofactors and regulatory proteins, and to interact with common cofactors in the presence of receptor-specific ligands. BRETFect was also used to follow the assembly of ternary complexes between the V2R vasopressin receptor and two different intracellular effectors, illustrating its use for dissection of ternary protein-protein interactions engaged by G protein-coupled receptors. Our results indicate that BRETFect represents a powerful and versatile technique to monitor the dynamics of ternary interactions within multimeric complexes in live cells.

An emerging link between LIM domain proteins and nuclear receptors.

Nuclear receptors are ligand-activated transcription factors that partake in several biological processes including development, reproduction and metabolism. Over the last decade, evidence has accumulated that group 2, 3 and 4 LIM domain proteins, primarily known for their roles in actin cytoskeleton organization, also partake in gene transcription regulation. They shuttle between the cytoplasm and the nucleus, amongst other as a consequence of triggering cells with ligands of nuclear receptors. LIM domain proteins act as important coregulators of nuclear receptor-mediated gene transcription, in which they can either function as coactivators or corepressors. In establishing interactions with nuclear receptors, the LIM domains are important, yet pleiotropy of LIM domain proteins and nuclear receptors frequently occurs. LIM domain protein-nuclear receptor complexes function in diverse physiological processes. Their association is, however, often linked to diseases including cancer.

An Accord of Nuclear Receptor Expression in M. tuberculosis Infected Macrophages and Dendritic Cells.

Mycobacterium tuberculosis instigates interactions with host factors to promote its survival within the host inimical conditions. Among such factors, nuclear receptors (NRs) seem to be promising candidates owing to their role in bacterial pathogenesis. However, only few members of NR superfamily have been implicated in M. tuberculosis infection and there is a dearth of comprehensive knowledge about expression or function of the entire superfamily. In this study, we performed detailed expression analysis and identified key NRs getting differentially regulated in murine macrophages and dendritic cells (DC) upon infection with H37Rv. The murine macrophages and DCs infected with H37Rv entailed overlapping changes in the expression of certain NRs which reflect upon the possibility that both cells might utilize similar transcriptional programs upon M. tuberculosis infection. We identified Nr4a3 and Rora, which have not been implicated in M. tuberculosis pathogenesis, undergo similar changes in expression in macrophages and DCs upon H37Rv infection. Interestingly, a similar pattern in their expression was also observed in infected human monocyte derived macrophages and the findings corroborated well with PBMCs obtained from TB patients. This all-inclusive analysis provides the basis for a precise approach in identifying NRs that can be targeted therapeutically in intracellular bacterial infections.

SRP, FtsY, DnaK and YidC Are Required for the Biogenesis of the E. coli Tail-Anchored Membrane Proteins DjlC and Flk.

Tail-anchored membrane proteins (TAMPs) are relatively simple membrane proteins characterized by a single transmembrane domain (TMD) at their C-terminus. Consequently, the hydrophobic TMD, which acts as a subcellular targeting signal, emerges from the ribosome only after termination of translation precluding canonical co-translational targeting and membrane insertion. In contrast to the well-studied eukaryotic TAMPs, surprisingly little is known about the cellular components that facilitate the biogenesis of bacterial TAMPs. In this study, we identify DjlC and Flk as bona fide Escherichia coli TAMPs and show that their TMDs are necessary and sufficient for authentic membrane targeting of the fluorescent reporter mNeonGreen. Using strains conditional for the expression of known E. coli membrane targeting and insertion factors, we demonstrate that the signal recognition particle (SRP), its receptor FtsY, the chaperone DnaK and insertase YidC are each required for efficient membrane localization of both TAMPs. A close association between the TMD of DjlC and Flk with both the Ffh subunit of SRP and YidC was confirmed by site-directed in vivo photo-crosslinking. In addition, our data suggest that the hydrophobicity of the TMD correlates with the dependency on SRP for efficient targeting.

Hepatic farnesoid X receptor protein level and circulating fibroblast growth factor 19 concentration in children with NAFLD.

BACKGROUND & AIMS: Treatment with the farnesoid X receptor (FXR) agonist obeticholic acid is ineffective in some patients with non-alcoholic steatohepatitis (NASH) but the explanation is uncertain. We investigated hepatic FXR expression, and measurements of fibroblast growth factor 19 (FGF19) and bile acids (BAs) in children with NAFLD to investigate relationships with NASH. METHODS: 33 children with NAFLD who underwent diagnostic liver biopsy were studied. Hepatic FXR protein levels and circulating FGF19 concentrations were compared with those analysed in five control subjects with proven normal liver histology. NASH was defined by the Paediatric NAFLD Histological Score (PNHS). Binary logistic regression with adjustment for covariates and potential confounders was undertaken to test factors independently associated with: a) NASH and b) hepatic FXR protein levels. RESULTS: Mean ± SD age was 13.7 ± 1.9 years. Nineteen patients had NASH (PNHS ≥ 85) and 14 did not have NASH (PNHS < 85). Hepatic FXR level and plasma FGF19 concentration varied ~10-fold and 5-fold, respectively, between groups, and was highest in control subjects, intermediate in NAFLD without NASH, and lowest in NASH (between group differences P < .001 and P < .01 respectively). NASH was independently associated with both FXR protein levels (OR = 0.18, 95% CI 0.09, 0.38) and FGF19 concentration (OR = 0.55, 95% CI 0.20, 0.89). CONCLUSIONS: FXR protein levels vary markedly between normal liver, NAFLD without NASH, and NASH. Low levels of FXR are independently associated with NASH.

Diagnostic value of alpha-1-fetoprotein (AFP) as a biomarker for hepatocellular carcinoma recurrence after liver transplantation.

BACKGROUND: Alpha-1-fetoprotein (AFP) is used to monitor progression, evaluate response to therapy and predict recurrence of hepatocellular carcinoma (HCC) in liver transplantation (LTx) patients. To date, the diagnostic value of serum AFP determinations for detecting tumor recurrence in HCC patients after LTx is unclear. OBJECTIVE: A retrospective, single-center, cross-sectional, non-interventional study was performed with the objective of determining post-transplant cut-off AFP values for detecting HCC recurrence post LTx. METHODS: Using receiver operating characteristic (ROC) analyses, post-transplant serum AFP values were evaluated against HCC recurrences in 63 HCC patients who had LTx between November 1995 and December 2011 at the University Medical Center Göttingen (UMG). Optimal and application-independent cut points for predicting tumor recurrence at 1, 3, and 5years after LTx were determined. RESULTS: Post-LTx serum AFP was found to represent an independent risk factor (predictor) for HCC relapse. Post-operative AFP cut-off values of 7µg/l, 6µg/l, and 6µg/l, respectively, were determined to be optimal at 1, 3, and 5years after LTx respectively for predicting a HCC relapse. Using these cut-off values, patients were correctly classified as relapse-positive with a diagnostic sensitivity of 79%, 81%, and 77%, and as relapse-free with a specificity of 82%, 79%, and 69%. The diagnostic accuracy measured by area under the curve (AUC) values ranged from 0.813 to 0.886. However, a limitation is that at a clinically relevant specificity of ≥95%, the analyses showed sensitivity values of only 50%, 52%, and 50%, respectively. CONCLUSION: Post-transplant serum AFP may have diagnostic value to detect HCC recurrence after LTx.