Prealbumin as a Predictor of Short-Term Prognosis in Patients with HBV-Related Acute-on-Chronic Liver Failure.

Purpose: Hepatitis B virus-related acute-on-chronic liver failure (HBV-ACLF) is a serious medical condition with a high short-term mortality rate, making accurate prognostic assessment essential for informed clinical decision-making. In this study, we aimed to develop a simple and effective prognostic model for predicting short-term mortality in patients with HBV-ACLF. Patients and Methods: To achieve our objective, we enrolled both a cross-sectional cohort (n = 291) and a retrospective cohort (n = 185) in this study. We collected laboratory and clinical data from these cohorts and performed univariate and multivariate logistic regression analyses to identify independent predictors of short-term mortality. Subsequently, we developed a novel prognostic score for HBV-ACLF, which was validated and assessed using receiver operating characteristic (ROC) curve analysis to determine its performance. Results: Our analysis revealed that the admission prealbumin (PAB) level was a robust independent predictor of 30-day mortality, with an area under the receiver operating characteristic (AUROC) of 0.760. Moreover, we developed the HIAPP score, a prognostic-score model based on PAB. The HIAPP score was significantly lower in survivors compared to non-survivors (-2.80±0.21 vs 0.97±0.41, P < 0.001). The HIAPP score's AUROC value was 0.899, which was found to be superior to the MELD score (AUROC = 0.795) and the CLIF-C ACLF score (AUC =0.781) and comparable to the COSSH-ACLF II score (AUC =0.825) for predicting 30-day mortality. These findings were also validated in a separate cohort, further supporting the utility of the HIAPP score as a prognostic tool for HBV-ACLF patients. Conclusion: Our study identifies the admission PAB level as a simple and valuable predictive index for 30-day mortality in HBV-ACLF patients. Furthermore, the HIAPP score, which incorporates PAB, PLT, INR, HE, and age, is an easy-to-use and pragmatic prognostic score in predicting short-term mortality.

Effect of X-ray radiation on the pharmacokinetics of apatinib in vivo in rats.

Purpose: The "radiotherapy-pharmacokinetic" ("RT-PK") phenomenon refers to the fact that radiation can significantly alter the pharmacokinetic behavior of a drug. At present, it is not clear whether there is an "RT-PK" phenomenon that can affect apatinib during concurrent chemoradiotherapy. In this study, we used a rat irradiation model to study the effects of X-ray radiation on absorption, tissue distribution, and excretion of apatinib. Method: Healthy Sprague-Dawley (SD) rats were randomly divided into control and radiation groups. The radiation group was given an appropriate dose of abdominal X-ray radiation, while the control group was not given irradiation. After 24 h of recovery, both groups were given apatinib solution 45 mg/kg by gavage. A quantitative LC-MS/MS method was developed to determine the concentration of apatinib in the rats, so as to compare the differences between the control and radiation groups and thus investigate the modulating effect of radiation on the pharmacokinetics of apatinib in rats. Results: After abdominal X-ray irradiation, the area under the curve (AUC0-t) of apatinib in rat plasma decreased by 33.8% and 76.3% at 0.5 and 2 Gy, respectively. Clearance (CL) and volume of distribution (Vd) increased and were positively correlated with radiation dose. X-ray radiation significantly reduced the concentration of apatinib in the liver and small intestine, and there was no tissue accumulation. In excretion studies, we found that X-ray radiation reduced the cumulative excretion of apatinib in feces and urine by 11.24% and 86.17%, respectively. Conclusion: Abdominal X-ray radiation decreased plasma exposure, tissue distribution, and excretion of apatinib in rats, suggesting that the RT-PK phenomenon affects apatinib. We speculate that this RT-PK phenomenon is closely related to changes in metabolic enzymes in vivo. In clinical practice, when apatinib is combined with radiotherapy, attention should be paid to adjusting the dose of apatinib and optimizing the treatment plan to alleviate the adverse effects of this RT-PK phenomenon.

Total serum bile acids predict therapy for HBeAg-negative chronic hepatitis B patients with borderline ALT and high HBV DNA.

INTRODUCTION: The introduction of antiviral therapy in chronic hepatitis B (CHB) infection depends on precise evaluation of hepatic lesions. Total serum bile acids (TSBAs) are highly sensitive in monitoring liver dysfunction. We evaluated the predictive role of TSBAs for hepatic lesions in CHB patients with borderline alanine aminotransferase (ALT) and high level of hepatitis B virus (HBV) DNA copies. METHODOLOGY: 328 CHB patients were enrolled, 241 were hepatitis B e antigen (HBeAg)-positive and 87 were HBeAg-negative. Patients were further divided into two entities according to inflammation/fibrosis evaluated by liver biopsy, low-grade (inflammation grade < 2 and fibrosis stage < 2) and high-grade (inflammation grade ≥ 2 or/and fibrosis stage ≥ 2) cohorts. TSBAs were compared with noninvasive tools including aspartate aminnotransferase (AST)-to-platelet ratio index (APRI), fibrosis-4 (FIB-4) and red cell distribution width (RDW)-to-platelet ratio (RPR) to predict high-grade hepatic lesions in CHB subgroups. RESULTS: TSBAs, APRI, FIB-4 and RPR were statistically different between low- and high-grade patients in HBeAg-positive cohort. Only TSBAs showed significant difference between low and high grade in HBeAg-negative patients. Similarly, APRI, FIB-4 and RPR were correlated with different division of inflammation/fibrosis only in HBeAg-positive while TSBAs were correlated with inflammation/fibrosis levels in both HBeAg-positive and HBeAg-negative groups. Of the four indicators, the receiver operating characteristic (ROC) curve analysis showed that TSBAs have the maximum AUC (area under the curve) in HBeAg-negative group but the minimum in HBeAg-positive cohort. CONCLUSIONS: TSBAs can be used for predicting antiviral therapy in CHB patients with HBeAg-negative, borderline ALT and high HBV DNA.

Non-clinical assessment of cell therapy products: the perspective from five Asian countries/regions based on regulatory guidelines and the underpinning rationales.

BACKGROUND AIMS: Cell-based regenerative medicine is an innovative field that can potentially alter the overall survival and quality of life of patients with devastating diseases. Several cell therapy products (CTPs) have been approved within the last two decades, and more are under development. The establishment of an effective developmental strategy in accordance with the regulatory bodies of each country/region is crucial for fast delivery of each respective CTP. In particular, facilitating investigational new drug (IND) approval is important for accelerating the transition from non-clinical to clinical research/trial phases. METHODS: Here the authors compared the non-clinical prerequisites for initiating clinical studies in five Asian countries/regions (India, China, Korea, Taiwan and Japan) from an industry viewpoint. The authors first identified the differences and tried to clarify the perspectives/considerations underpinning the different requirements. RESULTS: The authors' findings revealed that differences in regulations and development experiences, especially with CTPs, have led to clear differences in the non-clinical study package and its corresponding study design. CONCLUSIONS: By sharing experiences of the research and development of CTPs among Asian countries/regions and including not only industry but also regulatory authorities, we will be able to expedite cross-border IND approval and eventually contribute to the early delivery of innovative CTPs to many Asian patients.

[Polarization Modeling and Analysis of Light Scattering Properties of Multilayer Films on Slightly Rough Substrate].

To satisfy the demand of multilayer films on polarization detection, polarized bidirectional reflectance distribution function of multilayer films on slightly rough substrate is established on the basis of first-order vector perturbation theory and polarization transfer matrix. Due to the function, light scattering polarization properties are studied under multi-factor impacts of two typical targets-monolayer anti-reflection film and multilayer high-reflection films. The result shows that for monolayer anti-reflection film, observing positions have a great influence on the degree of polarization, for the left of the peak increased and right decreased compared with the substrate target. Film target and bare substrate can be distinguished by the degree of polarization in different observation angles. For multilayer high-reflection films, the degree of polarization is significantly associated with the number and optical thickness of layers at different wavelengths of incident light and scattering angles. With the increase of the layer number, the degree of polarization near the mirror reflection area decreases. It reveals that the calculated results coincide with the experimental data, which validates the correctness and rationality of the model. This paper provides a theoretical method for polarization detection of multilayer films target and reflection stealth technology.

[The Effect of Observation Geometry on Polarized Skylight Spectrum].

Study on polarized skylight spectral characters while observation geometry changing in different solar zenith angles (SZA), viewing zenith angles (VZA) or relative azimuth angles (RAA). Simulation calculation of cloudless daylight polarimetric spectrum is realized based on the solver, vector discrete ordinate method, of radiative transfer equation. In the Sun's principal and perpendicular plane, the spectral irradiance data, varying at wavelengths in the range between 0.4 and 3 µm, are calculated to extend the atmospheric polarization spectral information under the conditions: the MODTRAN solar reference spectrur is the only illuminant source; the main influencing factors of polarized radiative transfer include underlying surface albedo, aerosol layers and components, and the absorption of trace gases. Simulation analysis results: (1) While the relative azimuth angle is zero, the magnitude of spectrum U/I is lower than 10(-7) and V/I is negligible, the degree of polarization and the spectrum Q/I are shaped like the letter V or mirror-writing U. (2) In twilight, when the Sun is not in FOV of the detector, the polarization of the daytime sky has two maximum near 0.51 and 2.75 µm, and a minimum near 1.5 µm. For arbitrary observation geometry, the spectral signal of V/I may be ignored. According to observation geometry, choosing different spectral bands or polarized signal will be propitious to targets detection.

Clinicopathological features of an ascending colon mixed adenoneuroendocrine carcinoma with clinical serosal invasion.

Mixed adenoneuroendocrine carcinoma (MANEC) is exceedingly rare with a poor outcome. In this article, we reported a MANEC in a 68-year-old woman with a symptom of abdominal pain and distension. MANEC derived from the ascending colon with highly aggressive behavior. The diagnosis and distinguish of MANEC must base on histological findings and immunohistochemical findings. In this case, microscopic observation showed tumor cells were arranged in conglobate and nested by fibrous tissue with a visible cell atypia and mitotic. NEC-like and exocrine glandular cells were also been seen in a single neoplasm. MANEC tissues were immunopositive for CK, CK20, P53, CK7, CDX-2, Ki-67 (70%+), E-cad, CD56, CEA, Syn, villin and CgA, and immunonegative for CA125, NSE, ER and PR. Here, the patient was treated by surgical operation and was followed-up near 3 months, no local recurrence and distant metastasis.

A case of mucoepidermoid carcinoma located in the left forearm of a middle-aged pregnant woman.

In this article, we described a mucoepidermoid carcinoma (MEC) located in the left forearm of a 39-year-old pregnant woman. Here, the patient had a superficial tip size apophysis nearly 3 years, which begin to sustained growth after pregnant in 2012, and stopped growth after childbirth. MEC is a rare malignant tumor. Previously reports showed it mainly arise from the salivary, bronchial, thyroid, breast, lacrimal gland and conjunctiva. Here, we reported a case of MEC arising from the forearm gland for the first time. Histological finding showed a cystic and solid tumor in fibrous tissue below the squamous epithelium, and some columnar or cuboidal mucous cells covering on the epidermal cells or mixed with epidermal cells included in the tumor tissues. Also, Focal hyperplasia epidermal cells with round or oval nucleus in center were distributed in small pieces but no keratosis. The tumor tissues were immunopositive for CEA, P63, ki-67 (10%), CK7 and CK5/6, and immunonegative for CK20 and GCDFP-15. This case is a low-grade MEC and the patient's postoperative recovery is smooth.

Nasopharyngeal adenoid cystic carcinoma: a case report and review of the literature.

ACC derived from nasopharyngeal epithelial cells is rare, usually benign. In this article, we reported a nasopharyngeal adenoid cystic carcinoma (NACC) in a 31-year-old woman with a symptom of hoarseness, headache, epistaxis slightly, diplopia, facial numbness and dysphagia near 3 months. A tumor on the right side of the nasopharynx was confirmed by laryngoscope check and MRI of the skull base. Histopathological findings showed that tumor cells were arranged in cord-like or acinar-like by atypical hyperplastic epithelial cells forming a cribriform and tubular pattern, and immunohistochemical findings showed that tumor tissues were immunopositive for p63 (+), CK7 (+), CK19 (+), CK8 (+), CK18 (+), SMA (+), CK (+), p53 (++), S-100 (+) and Ki-67 (5%+), and negative for CD34 (-), CK5/6 (-), CEA (-) and CD117 (-). Patient was treated by surgical operation and radiotherapy, and was followed-up near 10 months, no local recurrence and distant metastasis.

Malignant myoepithelioma of the breast: a case report and review of literature.

In this article, we described a malignant myoepithelioma of the breast (MMB) in a 69-year-old woman. Breast cancer derived from myoepithelial cells is very rare, usually benign. The diagnosis of MMB based on histological and immunohistochemical finding. In this case, the author diagnosed the tumor as MMB, because tumor tissues were immunopositive for 34ßE12, P63, SMA, S-100, CD10, E-Cad and Ki-67, and immunnegative for CK5/6, desmin, ER, PR and C-erbB-2, because tumor tissue showed invasive growth and local hemorrhage or necrosis, suggesting malignant, and also because there was a transition between the tumor cells and hyperplastic myoepithelium of non-tumorous ducts. The patient's postoperative recovery is smooth and regular following of patient is essential.

Ovarian sclerosing stromal tumor in a young woman with ectopic pregnancy: clinical, pathological, and immunohistochemical studies.

In this article, we described an ovarian sclerosing stromal tumor (SST) in a young woman with ectopic pregnancy. It is important to distinguish SST from fibroma, thecoma, and lipoid cell tumors clinically and histologically. Several unique histologic features including pseudolobulation, sclerosis and prominent vascularity are clearly reflected at histopathological findings. The SST cells were immunopositive for CD34, Desmin and SMA, and negative for factor VIII-related antigen, CD31, S-100, ER and PR. The patient's postoperative recovery was smooth and she was discharged after 21 days.

Structure of native oligomeric Sprouty2 by electron microscopy and its property of electroconductivity.

Receptor tyrosine kinases (RTKs) regulate many cellular processes, and Sprouty2 (Spry2) is known as an important regulator of RTK signaling pathways. Therefore, it is worth investigating the properties of Spry2 in more detail. In this study, we found that Spry2 is able to self-assemble into oligomers with a high-affinity KD value of approximately 16nM, as determined through BIAcore surface plasmon resonance analysis. The three-dimensional (3D) structure of Spry2 was resolved using an electron microscopy (EM) single-particle reconstruction approach, which revealed that Spry2 is donut-shaped with two lip-cover domains. Furthermore, the method of energy dispersive spectrum obtained through EM was analyzed to determine the elements carried by Spry2, and the results demonstrated that Spry2 is a silicon- and iron-containing protein. The silicon may contribute to the electroconductivity of Spry2, and this property exhibits a concentration-dependent feature. This study provides the first report of a silicon- and iron-containing protein, and its 3D structure may allow us (1) to study the potential mechanism through the signal transduction is controlled by switching the electronic transfer on or off and (2) to develop a new type of conductor or even semiconductor using biological or half-biological hybrid materials in the future.

Selecting tyrosine kinase inhibitors for gastrointestinal stromal tumor with secondary KIT activation-loop domain mutations.

Advanced gastrointestinal stromal tumors (GIST), a KIT oncogene-driven tumor, on imatinib mesylate (IM) treatment may develop secondary KIT mutations to confer IM-resistant phenotype. Second-line sunitinib malate (SU) therapy is largely ineffective for IM-resistant GISTs with secondary exon 17 (activation-loop domain) mutations. We established an in vitro cell-based platform consisting of a series of COS-1 cells expressing KIT cDNA constructs encoding common primary±secondary mutations observed in GISTs, to compare the activity of several commercially available tyrosine kinase inhibitors on inhibiting the phosphorylation of mutant KIT proteins at their clinically achievable plasma steady-state concentration (Css). The inhibitory efficacies on KIT exon 11/17 mutants were further validated by growth inhibition assay on GIST48 cells, and underlying molecular-structure mechanisms were investigated by molecular modeling. Our results showed that SU more effectively inhibited mutant KIT with secondary exon 13 or 14 mutations than those with secondary exon 17 mutations, as clinically indicated. On contrary, at individual Css, nilotinib and sorafenib more profoundly inhibited the phosphorylation of KIT with secondary exon 17 mutations and the growth of GIST48 cells than IM, SU, and dasatinib. Molecular modeling analysis showed fragment deletion of exon 11 and point mutation on exon 17 would lead to a shift of KIT conformational equilibrium toward active form, for which nilotinib and sorafenib bound more stably than IM and SU. In current preclinical study, nilotinib and sorafenib are more active in IM-resistant GISTs with secondary exon 17 mutation than SU that deserve further clinical investigation.

Differential proteomic analysis of cancer stem cell properties in hepatocellular carcinomas by isobaric tag labeling and mass spectrometry.

Malignant tumors are relatively resistant to treatment due to their heterogeneous nature, drug resistance, and tendency for metastasis. Recent studies suggest that a subpopulation of cancer cells is responsible for the malignant outcomes. These cells are considered as cancer stem cells (CSC). Although a number of molecules have been identified in different cancer cells as markers for cancer stem cells, no promising markers are currently available for hepatocellular carcinoma cells. In this study, two clones of Hep3B cell lines were functionally characterized as control or CSC-like cells, based on properties including spheroid formation, drug resistance, and tumor initiation. Furthermore, their protein expression profiles were investigated by isobaric tags for relative and absolute quantitation (iTRAQ), and a total of 1,127 proteins were identified and quantified from the combined fractions; 50 proteins exhibited at least 2-fold differences between these two clones. These 50 proteins were analyzed by GeneGo and were found to be associated with liver neoplasms, hepatocellular carcinoma (HCC), and liver diseases. They were also components of metabolic pathways, immune responses, and cytoskeleton remodeling. Among these proteins, the expressions of S100P, S100A14, and vimentin were verified in several HCC cell lines, and their expressions were correlated with tumorigenicity in HCC cell lines. The functional significance of vimentin and S100A14 were also investigated and verified.

Therapeutic strategy for hair regeneration: hair cycle activation, niche environment modulation, wound-induced follicle neogenesis, and stem cell engineering.

INTRODUCTION: There are major new advancements in the fields of stem cell biology, developmental biology, regenerative hair cycling, and tissue engineering. The time is ripe to integrate, translate, and apply these findings to tissue engineering and regenerative medicine. Readers will learn about new progress in cellular and molecular aspects of hair follicle development, regeneration, and potential therapeutic opportunities these advances may offer. AREAS COVERED: Here, we use hair follicle formation to illustrate this progress and to identify targets for potential strategies in therapeutics. Hair regeneration is discussed in four different categories: i) Intra-follicle regeneration (or renewal) is the basic production of hair fibers from hair stem cells and dermal papillae in existing follicles. ii) Chimeric follicles via epithelial-mesenchymal recombination to identify stem cells and signaling centers. iii) Extra-follicular factors including local dermal and systemic factors can modulate the regenerative behavior of hair follicles, and may be relatively easy therapeutic targets. iv) Follicular neogenesis means the de novo formation of new follicles. In addition, scientists are working to engineer hair follicles, which require hair-forming competent epidermal cells and hair-inducing dermal cells. EXPERT OPINION: Ideally self-organizing processes similar to those occurring during embryonic development should be elicited with some help from biomaterials.

Novel azulene-based derivatives as potent multi-receptor tyrosine kinase inhibitors.

A series of azulene-based derivatives were synthesized as potent inhibitors for receptor tyrosine kinases such as FMS-like tyrosine kinase 3 (FLT-3). Systematic side chain modification of prototype 1a was carried out through SAR studies. Analogue 22 was identified from this series and found to be one of the most potent FLT-3 inhibitors, with good pharmaceutical properties, superior efficacy, and tolerability in a tumor xenograft model.

Synthesis and structure-activity relationship of 6-arylureido-3-pyrrol-2-ylmethylideneindolin-2-one derivatives as potent receptor tyrosine kinase inhibitors.

A series of new ureidoindolin-2-one derivatives were synthesized and evaluated as inhibitors of receptor tyrosine kinases. Investigation of structure-activity relationships at positions 5, 6, and 7 of the oxindole skeleton led to the identification of 6-ureido-substituted 3-pyrrolemethylidene-2-oxindole derivatives that potently inhibited both the vascular endothelial growth factor receptor (VEGFR) and platelet-derived growth factor receptor (PDGFR) families of receptor tyrosine kinases. Several derivatives showed potency against the PDGFR inhibiting both its enzymatic and cellular functions in the single-digit nanomolar range. Among them, compound 35 was a potent inhibitor against tyrosine kinases, including VEGFR and PDGFR families, as well as Aurora kinases. Inhibitor 36 (non-substituted on the pyrrole or phenyl ring) had a moderate pharmacokinetic profile and completely inhibited tumor growth initiated with the myeloid leukemia cell line, MV4-11, in a subcutaneous xenograft model in BALB/c nude mice.

Quercetin inhibition of tumor invasion via suppressing PKC delta/ERK/AP-1-dependent matrix metalloproteinase-9 activation in breast carcinoma cells.

Quercetin (QUE; 3,5,7,3',4'-tetrahydroxyflavone) has been shown to possess several beneficial biological activities including antitumor, anti-inflammation and antioxidant properties; however, the effects of QUE in preventing invasion by breast carcinoma cells are still undefined. Increases in the protein, messenger RNA and enzyme activity levels of matrix metalloproteinase (MMP)-9 were observed in 12-O-tetradecanoylphorbol-13-acetate (TPA)-treated MCF-7 cells, and these were blocked by QUE, but not by quercitrin or rutin. A translocation of protein kinase C (PKC)delta from the cytosol to the membrane followed by activation of extracellular signal-regulated kinase (ERK) and c-Jun/activator protein-1 (AP-1) by TPA was demonstrated, and TPA-induced MMP-9 activation and migration were inhibited by the pan PKC inhibitor, GF109203X, the specific PKCdelta inhibitor, rottlerin, an ERK inhibitor (PD98059) and an AP-1 inhibitor (curcumin). Application of QUE significantly suppressed TPA-induced activation of the PKCdelta/ERK/AP-1-signaling cascade. To elucidate the importance of hydroxyl (OH) substitutions to QUE's inhibition of tumor migration, several structurally related flavones of QUE including 3',4'-diOH, 3',4'-diOCH(3), 3,5,7-triOH, 3,4',4'-triOH, 3,3',4'-triOCH(3), luteolin and fisetin were used. Results suggested that OH groups at both C3' and C4' play central roles in QUE's inhibition of TPA-induced MMP-9 activation and migration, and an additional OH at C3, C5 or C7 may increase the inhibitory potency of the 3',4'-diOH flavone against TPA-induced MMP-9 activity and migration. The antitumor invasion and migration effects of breast carcinoma cells induced by QUE with the structure-activity relationship analysis were identified.

Variant in promoter region of platelet-derived growth factor receptor-alpha (PDGFRalpha) gene is associated with the severity and allergic status of childhood asthma.

BACKGROUND: Upregulation of the platelet-derived growth factor receptor-alpha (PDGFRalpha) in airway myofibroblast cells is one of the mechanisms of airway remodeling. The genetic association between PDGFRalpha promoter polymorphism and severity of childhood asthma was examined. METHODS: Five single nucleotide polymorphisms (SNPs) at the promoter regions of the PDGFRalpha gene were genotyped in 277 unrelated allergic and nonallergic asthmatic children and 93 age-matched controls. Promoter haplotypes were constructed using SNP genotyping data. The serum level of PDGF-AA, the ligand for PDGFRalpha, was assayed by ELISA kits. RESULTS: The genotype distribution of SNP rs1800810 (-1171G/C) in nonallergic asthma was significantly different from controls (p=0.038), as well as its allele distribution (p=0.028). Using haplotype analysis, the combination frequency of the low expression of H1 homozygous and heterozygous genotype (H1/H1+H1/H2) was significantly higher in nonallergic asthma as compared to controls (OR=1.94, CI=1.11-3.39, p<0.02). The frequency of H2/H2 homozygous was higher in persistent asthma than in intermittent asthma (p=0.008, OR=2.625). In addition, the PDGF-AA serum level in H2/H2 homozygous haplotype was significantly lower as compared to non-H2/H2 homozygous haplotype both in asthmatic (138.1+/-62.9 vs. 249.7+/-97.1 ng/ml, p<0.05) and nonallergic asthmatic children (113.8+/-38.0 vs. 256.6+/-58.3 ng/ml, p<0.05). CONCLUSIONS: The developmental deficiency due to the low expression of PDGFRalpha may be one of the susceptible factors for nonallergic asthmatic children. There was also an autocrine effect of lower PDGF-AA and higher PDGFRalpha expression that might lead to airway remodeling causing the severity of asthma.

Enhanced growth of human met-expressing xenografts in a new strain of immunocompromised mice transgenic for human hepatocyte growth factor/scatter factor.

Downstream signaling that results from the interaction of hepatocyte growth factor/scatter factor (HGF/SF) with the receptor tyrosine kinase Met plays critical roles in tumor development, progression, and metastasis. This ligand-receptor pair is an attractive target for new diagnostic and therapeutic agents, preclinical development of which requires suitable animal models. The growth of heterotopic and orthotopic Met-expressing human tumor xenografts in conventional strains of immunocompromised mice inadequately replicates the paracrine stimulation by human HGF/SF (hHGF/SF) that occurs in humans with cancer. We have therefore generated a mouse strain transgenic for hHGF/SF (designated hHGF-Tg) on a severe combined immunodeficiency (SCID) background. We report here that the presence of ectopically expressed hHGF/SF ligand significantly enhances growth of heterotopic subcutaneous xenografts derived from human Met-expressing cancer cells, including the lines SK-LMS-1 (human leiomyosarcoma), U118 (human glioblastoma), and DU145 (human prostate carcinoma), but not that of M14-Mel xenografts (human melanoma that expresses insignificant levels of Met). Our results indicate that ectopic hHGF/SF can specifically activate Met in human tumor xenografts. This new hHGF-Tg strain of mice should provide a powerful tool for evaluating drugs and diagnostic agents that target the various pathways influenced by Met activity.