Oncogenesis: An "Off-Target" Effect of Radiofrequency Ablation

PURPOSE

To compare hepatocellular carcinoma (HCC) development after radiofrequency (RF) ablation, partial surgical hepatectomy, and a sham operation and to inhibit HCC recurrence after RF ablation in a mouse model of spontaneously forming HCC in the setting of chronic inflammation (ie, the MDR2 knockout model).

MATERIALS AND METHODS

Animal experiments were performed according to an approved animal care committee protocol. The authors compared the survival of MDR2 knockout mice (an inflammation-induced HCC model) that underwent RF ablation, 35% partial hepatectomy (ie, left lobectomy), or a sham operation (controls) by using Kaplan-Meier survival curve analysis. Tumor load and tumor frequency in mice that underwent sham operation were further compared with those of mice treated with RF ablation at 1 month after therapy by using a two-tailed Student t test. Liver slices from mice treated with RF ablation were stained for α-smooth muscle actin and Ki-67 to establish the role of liver regeneration in the tumorigenic effect of RF ablation. Finally, tumor load and tumor incidence were evaluated in mice treated with a c-met inhibitor after RF ablation by using the Mann-Whitney U test.

RESULTS

Ablation of 3.5% ± 0.02 of the MDR2 knockout mice liver induced increased tumor load (P = .007) and reduced survival (P = .03) in comparison to that of controls, with no significant difference to the 10-fold volume removal of partial hepatectomy. Seven days after RF treatment, the border zone of the coagulation zone was surrounded by α-smooth muscle actin-positive activated myofibroblasts. A significant elevation of hepatocyte proliferation was also seen 7 days after RF ablation in the distant liver (ablated lobe: P = .003; untreated lobe: P = .02). A c-met inhibitor significantly attenuated HCC development in MDR2 knockout mice treated with RF ablation (P = .001).

CONCLUSION

Liver regeneration induced by RF ablation facilitates c-met/hepatocyte growth factor axis-dependent HCC tumor formation after treatment in the MDR2 knockout model. Blockage of the c-met/hepatocyte growth factor axis attenuates HCC recurrence, raising the potential for therapeutic intervention to reverse this potentially deleterious tumorigenic effect.

The knockdown of H19lncRNA reveals its regulatory role in pluripotency and tumorigenesis of human embryonic carcinoma cells

The function of imprinted H19 long non-coding RNA is still controversial. It is highly expressed in early embryogenesis and decreases after birth and re-expressed in cancer. To study the role of H19 in oncogenesis and pluripotency, we down-regulated H19 expression in vitro and in vivo in pluripotent human embryonic carcinoma (hEC) and embryonic stem (hES) cells. H19 knockdown resulted in a decrease in the expression of the pluripotency markers Oct4, Nanog, TRA-1-60 and TRA-1-81, and in the up-regulation of SSEA1; it further attenuated cell proliferation, decreased cell-matrix attachment, and up-regulated E-Cadherin expression. SCID-Beige mice transplanted with H19 down-regulated hEC cells exhibited slower kinetics of tumor formation, resulting in an increased animal survival. Tumors derived from H19 down-regulated cells showed a decrease in the expression of pluripotency markers and up-regulation of SSEA-1 and E-cadherin. Our results suggest that H19 oncogenicity in hEC cells is mediated through the regulation of the pluripotency state.

Multiple myeloma cells recruit tumor-supportive macrophages through the CXCR4/CXCL12 axis and promote their polarization toward the M2 phenotype

Multiple myeloma (MM) cells specifically attract peripheral-blood monocytes, while interaction of MM with bone marrow stromal cells (BMSCs) significantly increased monocyte recruitment (p<0.01). The CXCL12 chemokine, produced by both the MM and BMSCs, was found to be a critical regulator of monocyte migration. CXCL12 production was up-regulated under MM-BMSCs co-culture conditions, whereas blockage with anti-CXCR4 antibodies significantly abrogated monocyte recruitment toward a MM-derived conditioned medium (p<0.01). Furthermore, elevated levels of CXCL12 were detected in MM, but not in normal BM samples, whereas malignant MM cells often represented the source of increased CXCL12 in the BM. Blood-derived macrophages effectively supported MM cells proliferation and protected them from chemotherapy-induced apoptosis. Importantly, MM cells affected macrophage polarization, elevating the expression of M2-related scavenger receptor CD206 in macrophages and blocking LPS-induced TNFα secretion (a hallmark of M1 response). Of note, MM-educated macrophages suppressed T-cell proliferation and IFNγ production in response to activation. Finally, increased numbers of CXCR4-expressing CD163+CD206+ macrophages were detected in the BM of MM patients (n=25) in comparison to MGUS (n=11) and normal specimens (n=8).

Taken together, these results identify macrophages as important players in MM tumorogenicity, and recognize the CXCR4/CXCL12 axis as a critical regulator of MM-stroma interactions and microenvironment formation.

In vivo evidence suggesting reciprocal renal hypoxia-inducible factor-1 upregulation and signal transducer and activator of transcription 3 activation in response to hypoxic and non-hypoxic stimuli

In vitro studies suggest that combined activation of hypoxia-inducible factor (HIF) and signal transducer and activator of transcription 3 (STAT3) promotes the hypoxia response. However, their interrelationship in vivo remains poorly defined. The present study investigated the possible relationship between HIF-1 upregulation and STAT3 activation in the rodent kidney in vivo. Activation of HIF-1 and STAT3 was analysed by immunohistochemical staining and western blot analysis in: (i) models of hypoxia-associated kidney injury induced by radiocontrast media or rhabdomyolysis; (ii) following activation of STAT3 by the interleukin (IL)-6-soluble IL-6 receptor complex; or (iii) following HIF-1α stabilization using hypoxic and non-hypoxic stimuli (mimosine, FG-4497, CO, CoCl(2)) and in targeted von Hippel-Lindau-knockout mice. Western blot analysis and immunostaining revealed marked induction of both transcription factors under all conditions tested, suggesting that in vivo STAT3 can trigger HIF and vice versa. Colocalization of HIF-1α and phosphorylated STAT3 was detected in some, but not all, renal cell types, suggesting that in some cells a paracrine mechanism may be responsible for the reciprocal activation of the two transcription factors. Nevertheless, in several cell types spatial concordance was observed under the majority of conditions tested, suggesting that HIF-1 and STAT3 may act as cotranscription factors. These in vivo studies suggest that, in response to renal hypoxic-stress, upregulation of HIF-1 and activation of STAT3 may be both reciprocal and cell type dependent.

Systemic siRNA Nanoparticle-Based Drugs Combined with Radiofrequency Ablation for Cancer Therapy

PURPOSE

Radiofrequency thermal ablation (RFA) of hepatic and renal tumors can be accompanied by non-desired tumorigenesis in residual, untreated tumor. Here, we studied the use of micelle-encapsulated siRNA to suppress IL-6-mediated local and systemic secondary effects of RFA.

METHODS

We compared standardized hepatic or renal RFA (laparotomy, 1 cm active tip at 70 ± 2 °C for 5 min) and sham procedures without and with administration of 150 nm micelle-like nanoparticle (MNP) anti-IL6 siRNA (DOPE-PEI conjugates, single IP dose 15 min post-RFA, C57Bl mouse:3.5 ug/100ml, Fisher 344 rat: 20 ug/200 ul), RFA/scrambled siRNA, and RFA/empty MNPs. Outcome measures included: local periablational cellular infiltration (α-SMA+ stellate cells), regional hepatocyte proliferation, serum/tissue IL-6 and VEGF levels at 6-72 hr, and distant tumor growth, tumor proliferation (Ki-67) and microvascular density (MVD, CD34) in subcutaneous R3230 and MATBIII breast adenocarcinoma models at 7 days.

RESULTS

For liver RFA, adjuvant MNP anti-IL6 siRNA reduced RFA-induced increases in tissue IL-6 levels, α-SMA+ stellate cell infiltration, and regional hepatocyte proliferation to baseline (p < 0.04, all comparisons). Moreover, adjuvant MNP anti-IL6- siRNA suppressed increased distant tumor growth and Ki-67 observed in R3230 and MATBIII tumors post hepatic RFA (p<0.01). Anti-IL6 siRNA also reduced RFA-induced elevation in VEGF and tumor MVD (p < 0.01). Likewise, renal RFA-induced increases in serum IL-6 levels and distant R3230 tumor growth was suppressed with anti-IL6 siRNA (p < 0.01).

CONCLUSIONS

Adjuvant nanoparticle-encapsulated siRNA against IL-6 can be used to modulate local and regional effects of hepatic RFA to block potential unwanted pro-oncogenic effects of hepatic or renal RFA on distant tumor.

Chronic liver inflammation modifies DNA methylation at the precancerous stage of murine hepatocarcinogenesis

Chronic liver inflammation precedes the majority of hepatocellular carcinomas (HCC). Here, we explore the connection between chronic inflammation and DNA methylation in the liver at the late precancerous stages of HCC development in Mdr2(-/-) (Mdr2/Abcb4-knockout) mice, a model of inflammation-mediated HCC. Using methylated DNA immunoprecipitation followed by hybridization with "CpG islands" (CGIs) microarrays, we found specific CGIs in 76 genes which were hypermethylated in the Mdr2(-/-) liver compared to age-matched healthy controls. The observed hypermethylation resulted mainly from an age-dependent decrease of methylation of the specific CGIs in control livers with no decrease in mutant mice. Chronic inflammation did not change global levels of DNA methylation in Mdr2(-/-) liver, but caused a 2-fold decrease of the global 5-hydroxymethylcytosine level in mutants compared to controls. Liver cell fractionation revealed, that the relative hypermethylation of specific CGIs in Mdr2(-/-) livers affected either hepatocyte, or non-hepatocyte, or both fractions without a correlation between changes of gene methylation and expression. Our findings demonstrate that chronic liver inflammation causes hypermethylation of specific CGIs, which may affect both hepatocytes and non-hepatocyte liver cells. These changes may serve as useful markers of an increased regenerative activity and of a late precancerous stage in the chronically inflamed liver.

Specific genomic and transcriptomic aberrations in tumors induced by partial hepatectomy of a chronically inflamed murine liver

Resection of hepatocellular carcinoma (HCC) tumors by partial hepatectomy (PHx) is associated with promoting hepatocarcinogenesis. We have previously reported that PHx promotes hepatocarcinogenesis in the Mdr2-knockout (Mdr2-KO) mouse, a model for inflammation-mediated HCC. Now, to explore the molecular mechanisms underlying the tumor-promoting effect of PHx, we compared genomic and transcriptomic profiles of HCC tumors developing in the Mdr2-KO mice either spontaneously or following PHx. PHx accelerated HCC development in these mice by four months. PHx-induced tumors had major chromosomal aberrations: all were amplifications affecting multiple chromosomes. Most of these amplifications were located near the acrocentric centromeres of murine chromosomes. Four different chromosomal regions were amplified each in at least three tumors. The human orthologs of these common amplified regions are known to be amplified in HCC. All tumors of untreated mice had chromosomal aberrations, including both deletions and amplifications. Amplifications in spontaneous tumors affected fewer chromosomes and were not located preferentially at the chromosomal edges. Comparison of gene expression profiles revealed a significantly enriched expression of oncogenes, chromosomal instability markers and E2F1 targets in the post-PHx compared to spontaneous tumors. Both tumor groups shared the same frequent amplification at chromosome 18. Here, we revealed that one of the regulatory genes encoded by this amplified region, Crem, was over-expressed in the nuclei of murine and human HCC cells in vivo, and that it stimulated proliferation of human HCC cells in vitro. Our results demonstrate that PHx of a chronically inflamed liver directed tumor development to a discrete pathway characterized by amplification of specific chromosomal regions and expression of specific tumor-promoting genes. Crem is a new candidate HCC oncogene frequently amplified in this model and frequently over-expressed in human HCC.

Combination of imatinib with CXCR4 antagonist BKT140 overcomes the protective effect of stroma and targets CML in vitro and in vivo

Functional role of CXCR4 in chronic myelogenous leukemia (CML) progression was evaluated. Elevated CXCR4 significantly increased the in vitro survival and proliferation in response to CXCL12. CXCR4 stimulation resulted in activation of extracellular signal-regulated kinase (Erk)-1/2, Akt, S6K, STAT3, and STAT5 prosurvival signaling pathways. In accordance, we found that in vitro treatment with CXCR4 antagonist BKT140 directly inhibited the cell growth and induced cell death of CML cells. Combination of BKT140 with suboptimal concentrations of imatinib significantly increased the anti-CML effect. BKT140 induced apoptotic cell death, decreasing the levels of HSP70 and HSP90 chaperones and antiapoptotic proteins BCL-2 and BCL-XL, subsequently promoting the release of mitochondrial factors cytochrome c and SMAC/Diablo. Bone marrow (BM) stromal cells (BMSC) markedly increased the proliferation of CML cells and protected them from imatinib-induced apoptosis. Furthermore, BMSCs elevated proto-oncogene BCL6 expression in the CML cells in response to imatinib treatment, suggesting the possible role of BCL6 in stroma-mediated TKI resistance. BKT140 reversed the protective effect of the stroma, effectively promoted apoptosis, and decreased BCL6 levels in CML cells cocultured with BMSCs. BKT140 administration in vivo effectively reduced the growth of subcutaneous K562-produced xenografts. Moreover, the combination of BKT140 with low-dose imatinib markedly inhibited tumor growth, achieving 95% suppression. Taken together, our data indicate the importance of CXCR4/CXCL12 axis in CML growth and CML-BM stroma interaction. CXCR4 inhibition with BKT140 antagonist efficiently cooperated with imatinib in vitro and in vivo. These results provide the rational basis for CXCR4-targeted therapy in combination with TKI to override drug resistance and suppress residual disease.

Novel Kras-directed therapy in combination with chemotherapy for locally advanced pancreatic adenocarcinoma

270

Background: K-Ras mutation G12D is most prevalent in pancreatic adenocarcinoma (PDAC). siRNA against the K-RasG12D(siG12D) mutant had showed significant preclinical anti-tumor effects. siG12D LODER - is a miniature biodegradable polymeric matrix that encompasses anti K-RasG12D siRNA drug, designed to release the drug regionally along 4 months. The siG12D LODER is placed with Endoscopic US biopsy. Methods: Open label phase I study of patients with locally advanced non-operable PDAC in the first-line setting. Patients were assigned to receive siG12D LODERs in a dose escalation, dose cohorts were: 0.025mg, 0.75mg and 3.0mg. Gemcitabine 1000 mg/m2IV was given on a weekly basis, following the siG12D LODER insertion, until disease progression. The RP2D (recommended phase II dose) was further examined in highest dose cohort in combination with modified Folfirinox (Oxaliplatin 85mg/m2, Irinotecan 150mg/m2 followed by a Fluorouracil continuous IV infusion 2,400mg/m2 46 hours every 2 weeks). Follow up period was 8 weeks and survival follow up until death. Primary study objectives were to determine the dose-limiting toxicities (DLT) and maximum tolerated doses (MTD). Results: 15 patients with locally advanced PDAC have been enrolled. Two patients were omitted from study but followed for safety due to metastatic disease detected on day 1 post siG12D LODER implant imaging. Median age = 70 (range 52-85); male:female =8:7. Among 13 treated patients, the most frequent adverse events observed in the study were typically grade 1- 2 in severity; 4 patients experienced serious adverse events (SAE). No DLTs were observed. CT performed 8-12 weeks following the procedure showed tumor regression in 66% (8 of the first 12 patients, 7/8 from 2nd and 3rd cohorts).Reduction in tumor marker CA 19-9 was observed in 64% (7/11) of patients. Median overall survival was 16.26 months, 14.01 months and 15.11 months in the 0.025 mg, 0.75 mg and the 3 mg treatment groups respectively. Conclusions: The combination of siG12D LODER and chemotherapy is well tolerated. The combination has demonstrated promising efficacy in locally advanced pancreatic cancer with durable responses. NCT01188785. Clinical trial information: NCT01188785.

The high-affinity CXCR4 antagonist BKT140 is safe and induces a robust mobilization of human CD34+ cells in patients with multiple myeloma

PURPOSE

CXCR4 plays an important role in the retention of stem cells within the bone marrow. BKT140 (4F-benzoyl-TN14003) is a 14-residue bio stable synthetic peptide, which binds CXCR4 with a greater affinity compared with plerixafor (4 vs. 84 nmol/L). Studies in mice demonstrated the efficient and superior mobilization and transplantation of stem cells collected with GCSF-BKT140, compared with those obtained when using stem cells obtained with each one of these mobilizing agent alone. These results have served as a platform for the present clinical phase I study.

EXPERIMENTAL DESIGN

Eighteen patients with multiple myeloma who were preparing for their first autologous stem cell transplantation were included. Patients received a standard multiple myeloma mobilization regimen, consisting of 3 to 4 g/m(2) cyclophosphamide (day 0), followed by granulocyte colony-stimulating factor (G-CSF) at 5 μg/kg/d starting on day 5 and administered between 8 and 10 pm until the end of stem cell collection. A single injection of BKT140 (0.006, 0.03, 0.1, 0.3, and 0.9 mg/kg) was administered subcutaneously on day 10 in the early morning, followed by G-CSF 12 hours later.

RESULTS

BKT140 was well tolerated at all concentrations, and none of the patients developed grade 3 and 4 toxicity. A single administration of BKT140 at the highest dose, 0.9 mg/kg, resulted in a robust mobilization and collection of CD34(+) cells (20.6 ± 6.9 × 10(6)/kg), which were obtained through a single apheresis. All transplanted patients received ∼5.3 × 10(6) CD34(+) cells/kg, which rapidly engrafted (n = 17). The median time to neutrophil and platelet recovery was 12 and 14 days, respectively, at the highest dose (0.9 mg/kg).

CONCLUSIONS

When combined with G-CSF, BKT140 is a safe and efficient stem cell mobilizer that enabled the collection of a high number of CD34(+) cells in 1 and 2 aphaeresis procedures, resulting in successful engraftment.

Inflammation-induced hepatocellular carcinoma is dependent on CCR5 in mice

Human hepatocellular carcinoma (HCC) is an inflammation-induced cancer, which is the third-leading cause of cancer mortality worldwide. We investigated the role of the chemokine receptors, CCR5 and CCR1, in regulating inflammation and tumorigenesis in an inflammation-induced HCC model in mice. Multidrug resistance 2 gene (Mdr2)-knockout (Mdr2-KO) mice spontaneously develop chronic cholestatic hepatitis and fibrosis that is eventually followed by HCC. We generated two new strains from the Mdr2-KO mouse, the Mdr2:CCR5 and the Mdr2:CCR1 double knockouts (DKOs), and set out to compare inflammation and tumorigenesis among these strains. We found that in Mdr2-KO mice lacking the chemokine receptor, CCR5 (Mdr2:CCR5 DKO mice), but not CCR1 (Mdr2:CCR1 DKO), macrophage recruitment and trafficking to the liver was significantly reduced. Furthermore, in the absence of CCR5, reduced inflammation was also associated with reduced periductal accumulation of CD24(+) oval cells and abrogation of fibrosis. DKO mice for Mdr2 and CCR5 exhibited a significant decrease in tumor incidence and size.

CONCLUSIONS

Our results indicate that CCR5 has a critical role in both the development and progression of liver cancer. Therefore, we propose that a CCR5 antagonist can serve for HCC cancer prevention and treatment.

Transduction of fetal mice with a feline lentiviral vector induces liver tumors which exhibit an E2F activation signature

Lentiviral vectors are widely used in basic research and clinical applications for gene transfer and long-term expression; however, safety issues have not yet been completely resolved. In this study, we characterized hepatocarcinomas that developed in mice 1 year after in utero administration of a feline-derived lentiviral vector. Mapped viral integration sites differed among tumors and did not coincide with the regions of chromosomal aberrations. Furthermore, gene expression profiling revealed that no known cancer-associated genes were deregulated in the vicinity of viral integrations. Nevertheless, five of the six tumors exhibited highly significant upregulation of E2F target genes, of which a majority are associated with oncogenesis, DNA damage response, and chromosomal instability. We further show in vivo and in vitro that E2F activation occurs early on following transduction of both fetal mice and cultured human hepatocytes. On the basis of the similarities in E2F target gene expression patterns among tumors and the lack of evidence implicating insertional mutagenesis, we propose that transduction of fetal mice with a feline lentiviral vector induces E2F-mediated major cellular processes that drive hepatocytes toward uncontrolled proliferation culminating in tumorigenesis.

Interstrain differences in chronic hepatitis and tumor development in a murine model of inflammation-mediated hepatocarcinogenesis

Chronic inflammation is strongly associated with an increased risk for hepatocellular carcinoma (HCC) development. The multidrug resistance 2 (Mdr2)-knockout (KO) mouse (adenosine triphosphate-binding cassette b4(-/-) ), a model of inflammation-mediated HCC, develops chronic cholestatic hepatitis at an early age and HCC at an adult age. To delineate factors contributing to hepatocarcinogenesis, we compared the severity of early chronic hepatitis and late HCC development in two Mdr2-KO strains: Friend virus B-type/N (FVB) and C57 black 6 (B6). We demonstrated that hepatocarcinogenesis was significantly less efficient in the Mdr2-KO/B6 mice versus the Mdr2-KO/FVB mice; this difference was more prominent in males. Chronic hepatitis in the Mdr2-KO/B6 males was more severe at 1 month of age but was less severe at 3 months of age in comparison with age-matched Mdr2-KO/FVB males. A comparative genome-scale gene expression analysis of male livers of both strains at 3 months of age revealed both common and strain-specific aberrantly expressed genes, including genes associated with the regulation of inflammation, the response to oxidative stress, and lipid metabolism. One of these regulators, galectin-1 (Gal-1), possesses both anti-inflammatory and protumorigenic activities. To study its regulatory role in the liver, we transferred the Gal-1-KO mutation (lectin galactoside-binding soluble 1(-/-) ) from the B6 strain to the FVB strain, and we demonstrated that endogenous Gal-1 protected the liver against concanavalin A-induced hepatitis with the B6 genetic background but not the FVB genetic background.

CONCLUSION

Decreased chronic hepatitis in Mdr2-KO/B6 mice at the age of 3 months correlated with a significant retardation of liver tumor development in this strain versus the Mdr2-KO/FVB strain. We found candidate factors that may determine strain-specific differences in the course of chronic hepatitis and HCC development in the Mdr2-KO model, including inefficient anti-inflammatory activity of the endogenous lectin Gal-1 in the FVB strain.

A phase I trial of a local delivery of siRNA against k-ras in combination with chemotherapy for locally advanced pancreatic adenocarcinoma

4037

Background:K-Ras mutation G12D is most prevalent in pancreatic adenocarcinoma (PDAC). siRNA against the K-RasG12D(siG12D) mutant had showed significant preclinical anti-tumor effects. siG12D LODER - miniature biodegradable polymeric matrix that encompasses anti-K-RasG12D siRNA drug, is placed with Endoscopic US biopsy and designed to continuously release the drug regionally over a period of 4 months. Methods: Open label phase I study of patients with locally advanced non-operable PDAC in the first-line setting. Patients were assigned to receive siG12D LODERs in dose escalation cohorts: 0.025mg, 0.75mg and 3.0mg. Gemcitabine 1000 mg/m2IV was given weekly, following siG12D LODER insertion. The RP2D (recommended phase II dose) was further examined in 3.0 mg dose cohort in combination with modified Folfirinox (Oxaliplatin 85mg/m2, Irinotecan 150mg/m2, Fluorouracil infusion 2,400mg/m2 46 hours, every 2 weeks). Follow up period was 8 weeks and survival follow up until death. Primary study objectives were to determine the dose-limiting toxicities (DLT) and maximum tolerated doses (MTD). Results:15 patients have been enrolled. 2 patients were omitted from study due to metastatic disease detected on day 1 post siG12D LODER implant imaging . Median age = 70 (range 52-85); male:female 8:7. Among 13 treated patients, the most frequent adverse events observed in the study were typically grade 1- 2 in severity; 4 patients experienced serious adverse events (SAE), one procedure related. No DLTs were observed. MTD was not reached. CT performed 8-10 weeks following the procedure showed stable disease in all patients. Reduction in tumor marker CA 19-9 was observed in 64% (7/11) of patients. The median survival of 13 patients was 16 months ( 8/13 patients still alive at analysis). Conclusions: The combination of siG12D LODER and chemotherapy is well tolerated. The combination has demonstrated promising efficacy in locally advanced PDAC with durable responses. Phamocodynamic endpoints are currently being examined in an expansion cohort in operable patients. A phase II randomized trial is planned in order to investigate efficacy of siG12D LODER in locally advanced non-operable PDAC. Clinical trial information: NCT01188785.

Targeting the CD20 and CXCR4 pathways in non-hodgkin lymphoma with rituximab and high-affinity CXCR4 antagonist BKT140

PURPOSE

Chemokine axis CXCR4/CXCL12 is critically involved in the survival and trafficking of normal and malignant B lymphocytes. Here, we investigated the effect of high-affinity CXCR4 antagonist BKT140 on lymphoma cell growth and rituximab-induced cytotoxicity in vitro and in vivo.

EXPERIMENTAL DESIGN

In vitro efficacy of BKT140 alone or in combination with rituximab was determined in non-Hodgkin lymphoma (NHL) cell lines and primary samples from bone marrow aspirates of patients with NHL. In vivo efficacy was evaluated in xenograft models of localized and disseminated NHL with bone marrow involvement.

RESULTS

Antagonizing CXCR4 with BKT140 resulted in significant inhibition of CD20+ lymphoma cell growth and in the induction of cell death, respectively. Combination of BKT140 with rituximab significantly enhanced the apoptosis against the lymphoma cells in a dose-dependent manner. Moreover, rituximab induced CXCR4 expression in lymphoma cell lines and primary lymphoma cells, suggesting the possible interaction between CD20 and CXCR4 pathways in NHL. Primary bone marrow stromal cells (BMSC) further increased CXCR4 expression and protected NHL cells from rituximab-induced apoptosis, whereas BKT140 abrogated this protective effect. Furthermore, BKT140 showed efficient antilymphoma activity in vivo in the xenograft model of disseminated NHL with bone marrow involvement. BKT140 treatment inhibited the local tumor progression and significantly reduced the number of NHL cells in the bone marrow. Combined treatment of BKT140 with rituximab further decreased the number of viable lymphoma cells in the bone marrow, achieving 93% reduction.

CONCLUSIONS

These findings suggest the possible role of CXCR4 in NHL progression and response to rituximab and provide the scientific basis for the development of novel CXCR4-targeted therapies for refractory NHL.

Tumor STAT3 tyrosine phosphorylation status, as a predictor of benefit from adjuvant chemotherapy for breast cancer

Signal transducer and activator of transcription 3 (STAT3) is a point of convergence for numerous oncogenic signaling pathways. In breast cancer cell lines and xenograft models activated STAT3 participates in breast tumorigenesis, while studies in humans have demonstrated that phosphorylated (tyrosine705)-STAT3 is a marker of good prognosis in breast cancer. In order to resolve this paradox we hypothesized that in clinic, phospho-STAT3 has a predictive role of benefit from adjuvant chemotherapy; therefore the goal of this study was to determine the usefulness of phospho-STAT3 status as a predictor of benefit from adjuvant chemotherapy in breast cancer patients. Immunohistochemical analysis of phospho-STAT3 was performed on a tissue microarray of breast cancer specimens. The expression pattern of phospho-STAT3 was retrospectively correlated with pathological parameters and overall survival in patients who were or were not treated with adjuvant chemotherapy. Of 375 tissue specimens interpretable for phospho-STAT3, 134 (36 %) exhibited positive phospho-STAT3 nuclear expression. Among 234 patients who received adjuvant therapy, those with tumors displaying positive phospho-STAT3 nuclear expression had a better ten-year rate of overall survival than patients with tumors displaying negative phospho-STAT3 nuclear expression (P = 0.001). Among patients who did not received adjuvant chemotherapy, positive phospho-STAT3 nuclear status was not correlated with increased overall survival (P = 0.54). Positive phospho-STAT3 was correlated with improved overall survival only among patients who received adjuvant chemotherapy in a multivariate analysis adjusted for stage, grade, hormonal status, Her2 status, and age, irrespective of the chemotherapy regimen received (hazard ratio for death, 0.35 [95 % CI 0.188-0.667]; P = 0.001). These findings support the role of phospho-STAT3 as a marker of favorable outcome in breast cancer patients treated with adjuvant chemotherapy. Whether phospho-STAT3 has a predictive role of benefit from adjuvant chemotherapy has to be validated on prospective, randomized, controlled studies.

The regenerative activity of interleukin-6

Interleukin-6 (IL-6) is a cytokine which is involved in many inflammatory processes and in the development of cancer. In addition, IL-6 has been shown to be important for the induction of hepatic acute-phase proteins, for the regeneration of the liver and for the stimulation of B-cells. IL-6 binds to a transmembrane IL-6 receptor (IL-6R), which is present on hepatocytes and some leukocytes. The complex of IL-6 and IL-6R associates with a second protein, gp130, which is expressed on all cells of the body. Since neither IL-6 nor IL-6R has a measurable affinity for gp130, cells, which do not express IL-6R, are not responsive to the cytokine IL-6. It could be shown, however, that a naturally occurring soluble IL-6R (sIL-6R) in complex with IL-6 can bind to gp130 on cells with no IL-6R expression. Therefore, cells shedding the sIL-6R render cells, which only express gp130, responsive to the cytokine. This process has been called trans-signaling. In the present chapter, we summarize the known activities of IL-6 with a special emphasis on regenerative activities, which often depend on the sIL-6R. A designer cytokine called Hyper-IL-6, which is a fusion protein of IL-6 and the sIL-6R, can mimic IL-6 trans-signaling responses in vitro and in vivo with considerably higher efficacy than the combination of the natural proteins IL-6 and sIL-6R. We present recent examples from animal models in which the therapeutic potential of Hyper-IL-6 has been evaluated. We propose that Hyper-IL-6 can be used to induce potent regeneration responses in liver, kidney, and other tissues and therefore will be a novel therapeutic approach in regenerative medicine.

Tissue microarray-based study of patients with lymph node-positive breast cancer shows tyrosine phosphorylation of signal transducer and activator of transcription 3 (tyrosine705-STAT3) is a marker of good prognosis

BACKGROUND

Although lymph node-positive breast cancers are associated with poorer prognosis, individual patients may have different clinical outcomes. Signal transducer and activator of transcription 3 (STAT3) is a point of convergence for numerous oncogenic signalling pathways. The goal of this study was to determine the prognostic value of phosphorylated (tyrosine705)-STAT3 in node-positive breast cancer patients.

METHODS

Immunohistochemical analysis of Phospho- STAT3 was performed on a tissue microarray of breast cancer specimens. The expression pattern of Phospho-STAT3 was correlated with survival outcome, and clinical and pathological parameters.

RESULTS

Out of 125 interpretable tumours, positive Phospho- STAT3 nuclear expression was seen in 35 (28%) of tumours. There was no significant relationship between Phospho-STAT3 expression and clinical-pathological parameters including age, hormonal receptor status, grade and tumour size. Interestingly positive tumours had a significantly improved disease-free survival at 5 years (p=0.035). Additionally, positive Phospho-STAT3 nuclear expression was correlated with significantly improved survival at both 5 years (p=0.023) and 10 years (p=0.026). Finally, in multivariate analyses Phospho-STAT3 was found to be an independent prognostic marker of overall survival in node-positive breast cancer patients.

CONCLUSION

These findings support the role of Phospho- STAT3 as an important independent prognostic marker in node-positive breast cancer patients.

Subsurface femtosecond tissue alteration: selectively photobleaching macular degeneration pigments in near retinal contact

This paper uses advances in the ultrafast manipulation of light to address a general need in medicine for a clinical approach that can provide a solution to a variety of disorders requiring subsurface tissue manipulation with ultralow collateral damage. Examples are age-related macular degeneration (AMD), fungal infections, tumors surrounded by overlying tissue, cataracts, etc. Although lasers have revolutionized the use of light in clinical settings, most lasers employed in medicine cannot address such problems of depth-selective tissue manipulation. This arises from the fact that they are mostly based on one photon based laser tissue interactions that provide a cone of excitation where the energy density is sufficiently high to excite heat or fluorescence in the entire cone. Thus, it is difficult to excite a specific depth of a tissue without affecting the overlying surface. However, the advent of femtosecond (fs) lasers has caused a revolution in multiphoton microscopy (Zipfel et al. Nat. Biotechnol. 2003, 21, 1369-1377; Denk et al. Science 1990, 248, 73-76) and fabrication (Kawata et al. Nature 2001, 412, 697-698). With such lasers, the photon energy density is only high enough for multiphoton processes in the focal volume, and this opens a new direction to address subsurface tissue manipulation. Here we show in an AMD animal model, Ccr2 KO knockout mutant mice, noninvasive, selective fs two-photon photobleaching of pigments associated with AMD that accumulate under and in ultraclose proximity to the overlying retina. Pathological evidence is presented that indicates the lack of collateral damage to the overlying retina or other surrounding tissue.

Gene transfer to chicks using lentiviral vectors administered via the embryonic chorioallantoic membrane

The lack of affordable techniques for gene transfer in birds has inhibited the advancement of molecular studies in avian species. Here we demonstrate a new approach for introducing genes into chicken somatic tissues by administration of a lentiviral vector, derived from the feline immunodeficiency virus (FIV), into the chorioallantoic membrane (CAM) of chick embryos on embryonic day 11. The FIV-derived vectors carried yellow fluorescent protein (YFP) or recombinant alpha-melanocyte-stimulating hormone (α-MSH) genes, driven by the cytomegalovirus (CMV) promoter. Transgene expression, detected in chicks 2 days after hatch by quantitative real-time PCR, was mostly observed in the liver and spleen. Lower expression levels were also detected in the brain, kidney, heart and breast muscle. Immunofluorescence and flow cytometry analyses confirmed transgene expression in chick tissues at the protein level, demonstrating a transduction efficiency of ∼0.46% of liver cells. Integration of the viral vector into the chicken genome was demonstrated using genomic repetitive (CR1)-PCR amplification. Viability and stability of the transduced cells was confirmed using terminal deoxynucleotidyl transferase (dUTP) nick end labeling (TUNEL) assay, immunostaining with anti-proliferating cell nuclear antigen (anti-PCNA), and detection of transgene expression 51 days post transduction. Our approach led to only 9% drop in hatching efficiency compared to non-injected embryos, and all of the hatched chicks expressed the transgenes. We suggest that the transduction efficiency of FIV vectors combined with the accessibility of the CAM vasculature as a delivery route comprise a new powerful and practical approach for gene delivery into somatic tissues of chickens. Most relevant is the efficient transduction of the liver, which specializes in the production and secretion of proteins, thereby providing an optimal target for prolonged study of secreted hormones and peptides.

Efficient transgene expression from naked DNA delivered into an arterio-venous fistula model for kidney dialysis

BACKGROUND

Patients with kidney failure frequently require the formation of an arterio-venous fistula (AVF) in which a vein is connected to an artery resulting in arterialization of the vein to allow adequate blood flow into an external 'artificial kidney'. In most patients, neo-intimal hyperplasia (NIH) ensues, causing narrowing and subsequent occlusion of the vein, leading to significant morbidity. The cellular events causing venous NIH may serve as ideal targets for molecular-based therapies. However, therapeutic gene delivery into the vascular system is seriously impeded by problems related to the low efficacy and toxicity of targeted viral vector delivery.

MATERIALS AND METHODS

To explore the feasibility of a plasmid-based vascular gene delivery system, we established a rat AVF model that develops NIH. Plasmids encoding for reporter or therapeutic genes were delivered into the blood vessels at the time or after AVF formation.

RESULTS

Intra-luminal injection of plasmid into the AVF resulted in extensive and long-term reporter gene expression at the venous limb mainly at the site of NIH formation. Transgene expression was confined to endothelial cells and myofibroblasts that migrate inwards from the adventitia and form the NIH lesion. There was no detrimental tissue reaction to plasmid delivery, contrasting with the severe inflammatory response observed after adenovirus infection. Intra-vascular delivery of a plasmid carrying the endothelial nitric oxide synthase gene resulted in sustained production of nitric oxide, previously shown to mitigate NIH formation.

CONCLUSIONS

These findings open the possibility of vascular transduction with naked DNA bearing therapeutic genes in areas prone to NIH to ameliorate vein graft pathologies using simple and clinically applicable vector delivery methods.

Early hepatocyte DNA synthetic response posthepatectomy is modulated by IL-6 trans-signaling and PI3K/AKT activation

BACKGROUND & AIMS

Interleukin-6 (IL-6) is a crucial factor in liver regeneration following partial hepatectomy (PH); however, the role of IL-6 and IL-6 trans-signaling in particular, in hepatocyte mitosis remains controversial. IL-6 trans-signaling relies upon the release of the soluble IL-6R (sIL-6R), which binds IL-6 to form an agonistic IL-6/sIL-6R complex. Herein we have examined the hypothesis that IL-6 trans-signaling plays a crucial and distinct role in liver regeneration following PH.

METHODS

The specific IL-6/sIL-6R antagonist, sgp130Fc, was expressed in mice and analyzed for its effect on hepatocyte mitosis following PH. Alternatively, we examined the effect of the IL-6/sIL-6R super-agonist, Hyper-IL-6, or IL-6 expressed either alone or in combination with hepatocyte growth factor (HGF) on hepatocyte mitosis in the absence of PH.

RESULTS

Following PH, the dramatic rise of circulating IL-6 levels is accompanied by a concurrent ∼2-fold increase in circulating sIL-6R levels. Ectopic expression of sgp130Fc reduced hepatocyte mitosis by about 40% at early times following PH, while substantially reducing AKT, but not STAT3, activation. But, ectopic Hyper-IL-6 expression in mice without PH was not mitogenic to hepatocytes in vivo. Rather, Hyper-IL-6, but not IL-6, markedly increased HGF-induced hepatocyte mitosis. This cooperative effect correlated with greater resistance of HIL-6 than IL-6 to HGF-mediated reduction of AKT activation, rather than changes in STAT3 or MAPK signaling, and was completely blocked by PI3K inhibition.

CONCLUSIONS

Following PH, IL-6/sIL-6R cooperates with growth factors, through a PI3K/AKT-dependent mechanism to promote entry of hepatocytes into the cell cycle.

Ccr5 deficiency regulates the proliferation and trafficking of natural killer cells under physiological conditions

Chemokines were shown to govern the trafficking of immune cells and may also play important roles in the survival and activation of these cells. We report here that under physiological conditions, the bone marrow (BM), spleen, blood and liver of Ccr5, but not of Ccr1-deficient mice, contain reduced numbers of NK cells. NK cells in the BM of Ccr5-deficient mice proliferate to a lesser extent compared to WT mice. Furthermore, spleen NK cells derived from Ccr5-deficient mice that were transplanted into irradiated recipients failed to proliferate in the host. Ccr5, but not Ccr1-deficient NK cells, failed to migrate in vitro in response to RANTES and MIP-1β but not MIP-1β or SDF-1 and had reduced activation, lower expression levels of NK cell markers and a slightly reduced capacity to adhere to target cells and stimulate their killing. Using the polyI:C mouse model for NK trafficking, we found that in the absence of Ccr5, but not Ccr1, NK cells failed to accumulate in the liver. In contrast, using the influenza viral infection as a model to evaluate NK cell proliferation, we found that Ccr5-deficient NK cells in the BM had a higher proliferation rate than WT NK cells. These results suggest a role for Ccr5 in NK cell proliferation and circulation under physiological conditions and a complex role for Ccr5 in determining the fate of NK cells under pathological conditions.

Vascular profile characterization of liver tumors by magnetic resonance imaging using hemodynamic response imaging in mice

Recently, we have demonstrated the feasibility of using hemodynamic response imaging (HRI), a functional magnetic resonance imaging (MRI) method combined with hypercapnia and hyperoxia, for monitoring vascular changes during liver pathologies without the need of contrast material. In this study, we evaluated HRI ability to assess changes in liver tumor vasculature during tumor establishment, progression, and antiangiogenic therapy. Colorectal adenocarcinoma cells were injected intrasplenically to model colorectal liver metastasis (CRLM) and the Mdr2 knockout mice were used to model primary hepatic tumors. Hepatic perfusion parameters were evaluated using the HRI protocol and were compared with contrast-enhanced (CE) MRI. The hypovascularity and the increased arterial blood supply in well-defined CRLM were demonstrated by HRI. In CRLM-bearing mice, the entire liver perfusion was attenuated as the HRI maps were significantly reduced by 35%. This study demonstrates that the HRI method showed enhanced sensitivity for small CRLM (1-2 mm) detection compared with CE-MRI (82% versus 38%, respectively). In addition, HRI could demonstrate the vasculature alteration during CRLM progression (arborized vessels), which was further confirmed by histology. Moreover, HRI revealed the vascular changes induced by rapamycin treatment. Finally, HRI facilitates primary hepatic tumor characterization with good correlation to the pathologic differentiation. The HRI method is highly sensitive to subtle hemodynamic changes induced by CRLM and, hence, can function as an imaging tool for understanding the hemodynamic changes occurring during CRLM establishment, progression, and antiangiogenic treatment. In addition, this method facilitated the differentiation between different types of hepatic lesions based on their vascular profile noninvasively.

CXCR4 antagonist 4F-benzoyl-TN14003 inhibits leukemia and multiple myeloma tumor growth

OBJECTIVE

The chemokine receptor CXCR4 and its ligand CXCL12 are involved in the progression and dissemination of a diverse number of solid and hematological malignancies. Binding CXCL12 to CXCR4 activates a variety of intracellular signal transduction pathways that regulate cell chemotaxis, adhesion, survival, proliferation, and apoptosis.

MATERIALS AND METHODS

Here, we demonstrate that the CXCR4 antagonist, 4F-benzoyl-TN14003 (BKT140), but not AMD3100, exhibits a CXCR4-dependent preferential cytotoxicity toward malignant cells of hematopoietic origin. BKT140 significantly and preferentially stimulated multiple myeloma apoptotic cell death. BKT140 treatment induced morphological changes, phosphatidylserine externalization, decreased mitochondrial membrane potential, caspase-3 activation, sub-G1 arrest, and DNA double-stranded breaks.

RESULTS

In vivo, subcutaneous injections of BKT140 significantly reduced, in a dose-dependent manner, the growth of human acute myeloid leukemia and multiple myeloma xenografts. Tumors from animals treated with BKT140 were smaller in size and weights, had larger necrotic areas and high apoptotic scores.

CONCLUSIONS

Taken together, these results suggest a potential therapeutic use for BKT140 in multiple myeloma and leukemia patients.

Relevance of an academic GMP Pan-European vector infra-structure (PEVI)

In the past 5 years, European investigators have played a major role in the development of clinical gene therapy. The provision of substantial funds by some individual member states to construct GMP facilities makes it an opportune time to network available gene therapy GMP facilities at an EU level. The integrated coordination of GMP production facilities and human skills for advanced gene and genetically-modified (GM) cell therapy, can dramatically enhance academic-led "First-in-man" gene therapy trials. Once proof of efficacy is gathered, technology can be transferred to the private sector which will take over further development taking advantage of knowledge and know-how. Complex technical challenges require existing production facilities to adapt to emerging technologies in a coordinated manner. These include a mandatory requirement for the highest quality of production translating gene-transfer technologies with pharmaceutical-grade GMP processes to the clinic. A consensus has emerged on the directions and priorities to adopt, applying to advanced technologies with improved efficacy and safety profiles, in particular AAV, lentivirus-based and oncolytic vectors. Translating cutting-edge research into "First-in-man" trials require that pre-normative research is conducted which aims to develop standard assays, processes and candidate reference materials. This research will help harmonise practices and quality in the production of GMP vector lots and GM-cells. In gathering critical expertise in Europe and establish conditions for interoperability, the PEVI infrastructure will contribute to the demands of the advanced therapy medicinal products* regulation and to both health and quality of life of EU-citizens.

Efficient induction and selection of chloroplast-encoded antibiotic-resistant mutants in Nicotiana

A high rate of plastome-encoded mutations was induced in Nicotiana by exposing seeds to N-nitroso-N-methylurea. Seeds then were subjected to nutritional and in vitro selection procedures for systematic isolation of plastome-dependent antibiotic-resistant plants. Multiple flowering lines resistant to streptomycin, spectinomycin, lincomycin, or chloramphenicol were obtained. A detailed analysis of the streptomycin-resistant lines is presented. Sexual hybridization, cybrid formation following protoplast fusion, and in organello protein synthesis were used to rigorously assign the mutations to the chloroplast genome. The efficient rates of mutagenesis combined with the in vitro mass-screening procedures described here should facilitate investigation of fundamental aspects of chloroplast genetics in higher plants.

Gross E, Edrei Y, Ella E, Israel A, Cohen I, Corchia N, Ben-Moshe T, Pappo O, Pikarsky E, Goldenberg D, Shiloh Y, Galun E, Abramovitch R. Accelerated carcinogenesis following liver regeneration is associated with chronic inflammation-induced double-strand DNA breaks

Hepatocellular carcinoma (HCC) is the third leading cause of cancer mortality worldwide and is considered to be the outcome of chronic liver inflammation. Currently, the main treatment for HCC is surgical resection. However, survival rates are suboptimal partially because of tumor recurrence in the remaining liver. Our aim was to understand the molecular mechanisms linking liver regeneration under chronic inflammation to hepatic tumorigenesis. Mdr2-KO mice, a model of inflammation-associated cancer, underwent partial hepatectomy (PHx), which led to enhanced hepatocarcinogenesis. Moreover, liver regeneration in these mice was severely attenuated. We demonstrate the activation of the DNA damage-response machinery and increased genomic instability during early liver inflammatory stages resulting in hepatocyte apoptosis, cell-cycle arrest, and senescence and suggest their involvement in tumor growth acceleration subsequent to PHx. We propose that under the regenerative proliferative stress induced by liver resection, the genomic unstable hepatocytes generated during chronic inflammation escape senescence and apoptosis and reenter the cell cycle, triggering the enhanced tumorigenesis. Thus, we clarify the immediate and long-term contributions of the DNA damage response to HCC development and recurrence.

The oncofetal H19 RNA connection: hypoxia, p53 and cancer

Expression of the imprinted H19 gene is remarkably elevated in a large number of human cancers. Recently, we reported that H19 RNA is up-regulated in hypoxic stress and furthermore, it possesses oncogenic properties. However, the underlying mechanism(s) of these phenomena remain(s) unknown. Here we demonstrate a tight correlation between H19 RNA elevation by hypoxia and the status of the p53 tumor suppressor. Wild type p53 (p53(wt)) prevents the induction of H19 upon hypoxia, and upon its reconstitution in p53(null) cells. The last case is accompanied by a decrease in cell viability. The p53 effect is nuclear and seems independent of its tetramerization. Furthermore, using knockdown and over-expression approaches we identified HIF1-alpha as a critical factor that is responsible for H19 induction upon hypoxia. Knocking down HIF1-alpha abolishes H19 RNA induction, while its over-expression significantly enhances the H19 elevation in p53(null) hypoxic cells. In p53(wt) hypoxic cells simultaneous suppression of p53 and over-expression of HIF1-alpha are needed to induce H19 significantly, while each treatment separately resulting in a mild induction, indicating that the molecular mechanism of p53 suppression effect on H19 may at least in part involve interfering with HIF1-alpha activity. In vivo a significant increase in H19 expression occurred in tumors derived from p53(null) cells but not in p53(wt) cells. Taken together, our results indicate that a functional link exists between p53, HIF1-alpha and H19 that determines H19 elevation in hypoxic cancer cells. We suggest that this linkage plays a role in tumor development.

Comprehensive gene and microRNA expression profiling reveals a role for microRNAs in human liver development

BACKGROUND AND AIMS

microRNAs (miRNAs) are small noncoding RNAs that regulate cognate mRNAs post-transcriptionally. miRNAs have been implicated in regulating gene expression in embryonic developmental processes, including proliferation and differentiation. The liver is a multifunctional organ, which undergoes rapid changes during the developmental period and relies on tightly-regulated gene expression. Little is known regarding the complex expression patterns of both mRNAs and miRNAs during the early stages of human liver development, and the role of miRNAs in the regulation of this process has not been studied. The aim of this work was to study the impact of miRNAs on gene expression during early human liver development.

METHODS

Global gene and miRNA expression were profiled in adult and in 9-12w human embryonic livers, using high-density microarrays and quantitative RT-PCR.

RESULTS

Embryonic liver samples exhibited a gene expression profile that differentiated upon progression in the developmental process, and revealed multiple regulated genes. miRNA expression profiling revealed four major expression patterns that correlated with the known function of regulated miRNAs. Comparison of the expression of the most regulated miRNAs to that of their putative targets using a novel algorithm revealed a significant anti-correlation for several miRNAs, and identified the most active miRNAs in embryonic and in adult liver. Furthermore, our algorithm facilitated the identification of TGFbeta-R1 as a novel target gene of let-7.

CONCLUSIONS

Our results uncover multiple regulated miRNAs and genes throughout human liver development, and our algorithm assists in identification of novel miRNA targets with potential roles in liver development.

Focal liver necrosis appears early after partial hepatectomy and is dependent on T cells and antigen delivery from the gut

INTRODUCTION

Progressive liver failure may develop following removal of a large part of the liver or transplantation of a small for size liver graft. The pathophysiology of this clinical syndrome is only partially understood.

METHODS

We assessed liver damage and hepatocyte 5-bromo-2'-deoxyuridine (BrdU) incorporation following partial hepatectomy (PH) in C57BL/6, BALB/C and immune-deficient mice. Hepatic lymphocyte subpopulations were characterized. Lipopolysaccharide (LPS) treatment and bowel decontamination determined the role of gut antigens.

RESULTS

Discrete, round necrotic lesions were observed as early as 2 h following 70%, but not 30% PH. In immune competent mice the extent of hepatocyte necrosis inversely correlated with BrdU incorporation. T, natural killer and natural killer T cells were recruited to the liver early after PH; however, only T-cell depletion abrogated hepatic necrosis. Hepatic injury was significantly reduced in non-obese diabetic/severe combined immunodeficient mice undergoing PH, while BrdU incorporation was not affected. Liver injury was augmented by LPS injection and reduced by gut decontamination.

CONCLUSIONS

A distinct pattern of early focal hepatic necrosis is observed following extensive PH in mice. T cells infiltrating the liver immediately after PH and gut-derived antigens are indispensable for the observed liver necrosis and may thus provide therapeutic targets to ameliorate liver damage following PH.

Toll-like receptor 3 signaling attenuates liver regeneration

The current model for liver regeneration suggests that cell damage triggers Toll-like receptor (TLR) signaling via MyD88, leading to the induction of nuclear factor kappaB (NF-kappaB) and secretion of inflammatory cytokines that in turn prime liver regeneration. TLR3 is unique among TLRs in that it signals through TRIF (TIR domain-containing adaptor-inducing interferon-beta), not through MyD88, and may lead to activation of either the inflammatory or apoptotic pathway. The inflammatory pathway leads to NF-kappaB activation, whereas the apoptotic pathway, believed to be mediated by Rip3, leads to caspase-8 activation. In this study, we explored the role of TLR3 in liver regeneration by comparing the response to 70% partial hepatectomy of TLR3(wt) and TLR3(-/-) mice. We found that following partial hepatectomy, TLR3(-/-) mice demonstrated earlier hepatocyte proliferation. Furthermore, within the first hours, we observed a dramatic TLR3-dependent NF-kappaB activation and an increase in Rip3 levels in hepatocytes, accompanied by caspase-8 activation but without an apoptotic outcome.

CONCLUSION

TLR3 plays an inhibitory role in the priming of liver regeneration, thus reinforcing the role of the innate immune system in balancing tissue regeneration.

Increased microRNA activity in human cancers

MicroRNAs (miRNAs) are small regulatory RNAs that act by blocking the translation and increasing the degradation of target transcripts. MiRNAs play a critical role in many biological processes including development and differentiation and many studies have shown that major changes in miRNA levels occur in cancer. Since miRNAs degrade target messages, we used this property to develop a novel computational method aimed at determining the actual biological activity of miRNAs using variations in gene expression. Using the method described here, we quantified miRNA activity in papillary thyroid carcinoma and breast cancer, and found a strong and distinctive signal of increased global miRNA activity, embedded in the pertaining gene expression measurements. Interestingly, we found that in these two cancers, miRNA activity is globally increased, and is associated with a global downregulation of miRNA target genes. This downreguation of miRNA regulated genes is particularly noticeable for genes carrying multiple target sites for miRNAs. Among the miRNA-repressed genes, we found a significant enrichment of known tumor suppressors, thereby suggesting that the increased miRNA activity was indeed tumorigenic.

Interaction between CXCR4 and CCL20 pathways regulates tumor growth

The chemokine receptor CXCR4 and its ligand CXCL12 is overexpressed in the majority of tumors and is critically involved in the development and metastasis of these tumors. CXCR4 is expressed in malignant tumor cells whereas its ligand SDF-1 (CXCL12) is expressed mainly by cancer associated fibroblasts (CAF). Similarly to CXCR4, the chemokine CCL20 is overexpressed in variety of tumors; however its role and regulation in tumors is not fully clear. Here, we show that the chemokine receptor CXCR4 stimulates the production of the chemokine CCL20 and that CCL20 stimulates the proliferation and adhesion to collagen of various tumor cells. Furthermore, overexpression of CCL20 in tumor cells promotes growth and adhesion in vitro and increased tumor growth and invasiveness in vivo. Moreover, neutralizing antibodies to CCL20 inhibit the in vivo growth of tumors that either overexpress CXCR4 or CCL20 or naturally express CCL20. These results reveal a role for CCL20 in CXCR4-dependent and -independent tumor growth and suggest a therapeutic potential for CCL20 and CCR6 antagonists in the treatment of CXCR4- and CCL20-dependent malignancies.

HCV tumor promoting effect is dependent on host genetic background

BACKGROUND

The hepatitis C virus (HCV) is one of the major risk factors for the development of hepatocellular carcinoma (HCC). Nevertheless, transgenic mice which express the whole HCV polyprotein (HCV-Tg) do not develop HCC. Whereas chronic HCV infection causes inflammation in patients, in HCV-Tg mice, the host immune reaction against viral proteins is lacking. We aimed to test the role of HCV proteins in HCC development on the background of chronic inflammation in vivo.

METHODOLOGY/PRINCIPAL FINDINGS

We crossed HCV-Tg mice that do not develop HCC with the Mdr2-knockout (Mdr2-KO) mice which develop inflammation-associated HCC, to generate Mdr2-KO/HCV-Tg mice. We studied the effect of the HCV transgene on tumor incidence, hepatocyte mitosis and apoptosis, and investigated the potential contributing factors for the generated phenotype by gene expression and protein analyses. The Mdr2-KO/HCV-Tg females from the N2 generation of this breeding (having 75% of the FVB/N genome and 25% of the C57BL/6 genome) produced significantly larger tumors in comparison with Mdr2-KO mice. In parallel, the Mdr2-KO/HCV-Tg females had an enhanced inflammatory gene expression signature. However, in the N7 generation (having 99.2% of the FVB/N genome and 0.8% of the C57BL/6 genome) there was no difference in tumor development between Mdr2-KO/HCV-Tg and Mdr2-KO animals of both sexes. The HCV transgene was similarly expressed in the livers of Mdr2-KO/HCV-Tg females of both generations, as revealed by detection of the HCV transcript and the core protein.

CONCLUSION

These findings suggest that the HCV transgene accelerated inflammation-associated hepatocarcinogenesis in a host genetic background-dependent manner.

MicroRNA expression patterns and function in endodermal differentiation of human embryonic stem cells

BACKGROUND/AIMS

microRNAs (miRNAs) are small noncoding RNAs that regulate cognate mRNAs post-transcriptionally. Human embryonic stem cells (hESC), which exhibit the characteristics of pluripotency and self-renewal, may serve as a model to study the role of miRNAs in early human development. We aimed to determine whether endodermally-differentiated hESC demonstrate a unique miRNA expression pattern, and whether overexpression of endoderm-specific miRNA may affect hESC differentiation.

METHODS

miRNA expression was profiled in undifferentiated and NaButyrate-induced differentiated hESC of two lines, using microarray and quantitative RT-PCR. Then, the effect of lentiviral-based overexpression of liver-specific miR-122 on hESC differentiation was analyzed, using genomewide gene microarrays.

RESULTS

The miRNA profiling revealed expression of three novel miRNAs in undifferentiated and differentiated hESC. Upon NaButyrate induction, two of the most upregulated miRNAs common to both cell lines were miR-24 and miR-10a, whose target genes have been shown to inhibit endodermal differentiation. Furthermore, induction of several liver-enriched miRNAs, including miR-122 and miR-192, was observed in parallel to induction of endodermal gene expression. Stable overexpression of miR-122 in hESC was unable to direct spontaneous differentiation towards a clear endodermal fate, but rather, delayed general differentiation of these cells.

CONCLUSIONS

Our results demonstrate that expression of specific miRNAs correlates with that of specific genes upon differentiation, and highlight the potential role of miRNAs in endodermal differentiation of hESC.

Functional magnetic resonance imaging monitoring of pathological changes in rodent livers during hyperoxia and hypercapnia

Liver diseases and regeneration are associated with hemodynamic changes denoting pathological alterations. Determining and monitoring physiological and pathological liver changes is essential for diagnostic and therapeutic objectives. Our aim was to determine the feasibility of functional magnetic resonance imaging (fMRI) during hypercapnia and hyperoxia for monitoring liver pathology. Liver fMRI images were acquired in rodents following acute bleeding, partial hepatectomy, and fibrosis. Results were quantitated and confirmed by histology. Changes induced by hyperoxia and hypercapnia following hemorrhage significantly correlated with the percentage of blood loss, reflecting lower liver perfusion and diminished vessel responsiveness to gas saturation. Hepatectomy resulted in an early decline in signal intensity changes due to hyperoxia, suggesting a decrease in liver perfusion and blood content. Following hepatectomy, signal intensity changes due to hypercapnia increased, signifying a change in liver perfusion from a mainly portal to a more arterial source. Two weeks after induction of fibrosis, signal intensity changes due to hypercapnia became much lower and those due to hyperoxia were much higher than those in normal livers, reflecting the increased perfusion due to the inflammatory process as confirmed by histologic analysis. With fibrosis progression, signal intensity changes induced by hypercapnia and hyperoxia were gradually attenuated, indicating structural and functional alterations of the liver vasculature during fibrosis.

CONCLUSION

In various liver pathologies, fMRI response to hypercapnia and hyperoxia is sensitive to changes in liver hemodynamic status involved in hepatic damage or recovery; thus, this technique may offer an additional noninvasive diagnostic tool for evaluation and follow-up of liver diseases by means of examining perfusion-related alterations.

IL-6/IL-6R axis plays a critical role in acute kidney injury

The response to tissue injury involves the coordination of inflammatory and repair processes. IL-6 expression correlates with the onset and severity of acute kidney injury (AKI), but its contribution to pathogenesis remains unclear. This study established a critical role for IL-6 in both the inflammatory response and the resolution of AKI. IL-6-deficient mice were resistant to HgCl2-induced AKI compared with wild-type mice. The accumulation of peritubular neutrophils was lower in IL-6-deficient mice than in wild-type mice, and neutrophil depletion before HgCl2 administration in wild-type mice significantly reduced AKI; these results demonstrate the critical role of IL-6 signaling in the injurious inflammatory process in AKI. Renal IL-6 expression and STAT3 activation in renal tubular epithelial cells significantly increased during the development of injury, suggesting active IL-6 signaling. Although a lack of renal IL-6 receptors (IL-6R) precludes the activation of classical signaling pathways, IL-6 can stimulate target cells together with a soluble form of the IL-6R (sIL-6R) in a process termed trans-signaling. During injury,serum sIL-6R levels increased three-fold, suggesting a possible role for IL-6 trans-signaling in AKI. Stimulation of IL-6 trans-signaling with an IL-6/sIL-6R fusion protein activated STAT3 in renal tubular epithelium and prevented AKI. IL-6/sIL-6R reduced lipid peroxidation after injury, suggesting that its protective effect may be largely mediated through amelioration of oxidative stress. In summary, IL-6 simultaneously promotes an injurious inflammatory response and, through a mechanism of trans-signaling, protects the kidney from further injury.

Molecular mechanisms of liver carcinogenesis in the mdr2-knockout mice

Mouse models of hepatocellular carcinoma (HCC) simulate specific subgroups of human HCC. We investigated hepatocarcinogenesis in Mdr2-knockout (Mdr2-KO) mice, a model of inflammation-associated HCC, using gene expression profiling and immunohistochemical analyses. Gene expression profiling showed that although Mdr2-KO mice differ from other published murine HCC models, they share several important deregulated pathways and many coordinately differentially expressed genes with human HCC data sets. Analysis of genome positions of differentially expressed genes in liver tumors revealed a prolonged region of down-regulated genes on murine chromosome 8 in three of the six analyzed tumor samples. This region is syntenic to human chromosomal regions that are frequently deleted in human HCC and harbor multiple tumor suppressor genes. Real-time reverse transcription-PCR analysis of 16 tumor samples confirmed down-regulation of several tumor suppressors in most tumors. We show that in the aged Mdr2-KO mice, cyclin D1 nuclear level is increased in dysplastic hepatocytes that do not form nodules; however, it is decreased in most dysplastic nodules and in liver tumors. We found that this decrease is mostly at the protein, rather than the mRNA, level. These findings raise the question on the role of cyclin D1 at early stages of hepatocarcinogenesis in the Mdr2-KO HCC model. Furthermore, we show that most liver tumors in Mdr2-KO mice were characterized by the absence of beta-catenin activation. In conclusion, the Mdr2-KO mouse may serve as a model for beta-catenin-negative subgroup of human HCCs characterized by low nuclear cyclin D1 levels in tumor cells and by down-regulation of multiple tumor suppressor genes.

The H19 non-coding RNA is essential for human tumor growth

Background

Mutations and epigenetic aberrant signaling of growth factors pathways contribute to carcinogenesis. Recent studies reveal that non-coding RNAs are controllers of gene expression. H19 is an imprinted gene that demonstrates maternal monoallelic expression without a protein product; although its expression is shut off in most tissues postnatally, it is re-activated during adult tissue regeneration and tumorigenesis. Moreover, H19 is highly expressed in liver metastasis derived from a range of carcinomas. The objective of this study is to explore the role of H19 in carcinogenesis, and to determine its identification as an anti-tumor target.

Methodology/ Principle Findings

By controlling oxygen pressure during tumor cell growth and H19 expression levels, we investigated the role of H19 expression in vitro and in vivo in hepatocellular (HCC) and bladder carcinoma. Hypoxia upregulates the level of H19 RNA. Ablations of tumorigenicity of HCC and bladder carcinomas in vivo are seen by H19 knockdown which also significantly abrogates anchorage-independent growth after hypoxia recovery, while ectopic H19 expression enhances tumorigenic potential of carcinoma cells in vivo. Knocking-down H19 message in hypoxic stress severely diminishes p57^kip2 induction. We identified a number of potential downstream targets of H19 RNA, including angiogenin and FGF18.

Conclusions

H19 RNA harbors pro-tumorigenic properties, thus the H19 gene behaves as an oncogene and may serve as a potential new target for anti-tumor therapy.

Testing transgenic regulatory elements through live mouse imaging

To overcome positional and methylation effects on transgene expression, we developed a universal cloning cassette for in vivo assessment of regulatory elements using the luciferase reporter gene and the CCCD camera. Monitoring luciferase expression pattern in live mice enables screening of large numbers of transgenic founders quickly and inexpensively. We demonstrate that in the engineered transgenic mice, the chicken beta-globin 5'HS4 insulator did not always provide the desirable expression pattern, and the Island Element, responsible for the demethylation of the surrounding DNA region, was not beneficial. Both tested liver-specific and developmentally regulated promoters exhibited the expected expression pattern in most transgenic founders.

Attenuation of reperfusion lung injury and apoptosis by A2A adenosine receptor activation is associated with modulation of Bcl-2 and Bax expression and activation of extracellular signal-regulated kinases

Adenosine receptors (AR) and extracellular signal-regulated kinases (ERK) have been implicated in tissue protection and apoptosis regulation during ischemia/reperfusion (I/R) injury. This study tests the hypothesis that reduction of reperfusion lung injury after A2A AR activation is associated with attenuation of apoptosis, modulation of ERK activation, and alterations in antiapoptotic and proapoptotic protein expression (Bcl-2 and Bax, respectively). Experiments were performed in intact-chest, spontaneously breathing cats in which the arterial branch of the left lower lung lobe was occluded for 2 h and reperfused for 3 h (I/R group). Animals were treated with the selective A2A AR agonist ATL313 given 5 min before reperfusion alone or in combination with the selective A2A AR antagonist ZM241385. Western blot analysis showed significant reduction in expression of Bcl-2 and increase in expression of Bax after reperfusion, compared with control lungs. Phosphorylated ERK1/2 levels were also increased after reperfusion. Compared with the I/R group, ATL313 markedly (P < 0.01) attenuated indices of injury and apoptosis including the percentage of injured alveoli, wet-dry weight ratio, myeloperoxidase activity, in situ terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling-positive cells, and caspase 3 activity and expression. Furthermore, compared with reperfused lungs, in ATL313-pretreated lungs, Western blot analysis demonstrated substantial ERK1/2 activation, increased expression of Bcl-2, and attenuated expression of Bax. The protective effects of ATL313 were blocked by pretreatment with ZM241385. In summary, the present study shows that in vivo activation of A2A AR confers protection against reperfusion lung injury. This protection is associated with decreased apoptosis and involves ERK1/2 activation and alterations in antiapoptotic Bcl-2 and proapoptotic Bax proteins.

Chemokines in hepatitis C virus infection: Pathogenesis, prognosis and therapeutics

Hepatitis C virus infection and its associated liver inflammatory disease is a major global health problem affecting over 170 million people worldwide. Following viral infection, multiple pro-inflammatory mediators contribute to recruitment of immune cells to the liver and to the generation of an anti-viral immune response. However, when this vigorous immune response fails to eliminate the virus, chronic infection is established. This in turn, results in an ongoing process of inflammation, regeneration and fibrosis that in many cases leads to the development of cirrhosis and of hepatocellular carcinoma. Multiple recent publications mark chemokines and their receptors as key players in leukocyte recirculation through the inflamed liver. Furthermore, chemokines may also be involved in liver regeneration, fibrosis, and in malignant transformation, which is induced by the persistence of inflammation. Accumulating data indicates that distinct chemokines and chemokine receptors may be associated with different stages of the chronic hepatitis C virus infection-associated liver disease. Multiple small molecules and peptide antagonizing chemokines and their receptors are in advanced phase 3 and phase 2 clinical trials. In the near future, such drugs are expected to enter clinical use raising the question whether they may be applicable for the treatment of chronic viral infection-associated liver disease. In this review, recent advances in understanding the role of chemokines and their receptors in the pathogenesis of chronic viral infection-associated liver disease are presented. Furthermore, the clinical implications of these novel findings, which mark chemokines as prognostic markers and therapeutic targets for immune-modulation during chronic liver viral infection, are documented.