Dendritic cell paucity in mismatch repair-proficient colorectal cancer liver metastases limits immune checkpoint blockade efficacy

Liver metastasis is a major cause of mortality for patients with colorectal cancer (CRC). Mismatch repair-proficient (pMMR) CRCs make up about 95% of metastatic CRCs, and are unresponsive to immune checkpoint blockade (ICB) therapy. Here we show that mouse models of orthotopic pMMR CRC liver metastasis accurately recapitulate the inefficacy of ICB therapy in patients, whereas the same pMMR CRC tumors are sensitive to ICB therapy when grown subcutaneously. To reveal local, nonmalignant components that determine CRC sensitivity to treatment, we compared the microenvironments of pMMR CRC cells grown as liver metastases and subcutaneous tumors. We found a paucity of both activated T cells and dendritic cells in ICB-treated orthotopic liver metastases, when compared with their subcutaneous tumor counterparts. Furthermore, treatment with Feline McDonough sarcoma (FMS)-like tyrosine kinase 3 ligand (Flt3L) plus ICB therapy increased dendritic cell infiltration into pMMR CRC liver metastases and improved mouse survival. Lastly, we show that human CRC liver metastases and microsatellite stable (MSS) primary CRC have a similar paucity of T cells and dendritic cells. These studies indicate that orthotopic tumor models, but not subcutaneous models, should be used to guide human clinical trials. Our findings also posit dendritic cells as antitumor components that can increase the efficacy of immunotherapies against pMMR CRC.

Oral administration of bovine milk-derived extracellular vesicles induces senescence in the primary tumor but accelerates cancer metastasis

The concept that extracellular vesicles (EVs) from the diet can be absorbed by the intestinal tract of the consuming organism, be bioavailable in various organs, and in-turn exert phenotypic changes is highly debatable. Here, we isolate EVs from both raw and commercial bovine milk and characterize them by electron microscopy, nanoparticle tracking analysis, western blotting, quantitative proteomics and small RNA sequencing analysis. Orally administered bovine milk-derived EVs survive the harsh degrading conditions of the gut, in mice, and is subsequently detected in multiple organs. Milk-derived EVs orally administered to mice implanted with colorectal and breast cancer cells reduce the primary tumor burden. Intriguingly, despite the reduction in primary tumor growth, milk-derived EVs accelerate metastasis in breast and pancreatic cancer mouse models. Proteomic and biochemical analysis reveal the induction of senescence and epithelial-to-mesenchymal transition in cancer cells upon treatment with milk-derived EVs. Timing of EV administration is critical as oral administration after resection of the primary tumor reverses the pro-metastatic effects of milk-derived EVs in breast cancer models. Taken together, our study provides context-based and opposing roles of milk-derived EVs as metastasis inducers and suppressors.

Oral siRNA delivery using dual transporting systems to efficiently treat colorectal liver metastasis

Oral siRNA delivery is an ideal way to translate siRNA therapeutic effects in the clinic due to its ability to be administered in convenient and multiple dosages. However, an effective oral delivery system requires overcoming both a hostile gastrointestinal (GI) environment and non-specific targeting. Here, an HTsRP-NC system is a new oral siRNA delivery system consisting of a siRNA/protamine (sRP) nano-complex protected by a multi-functional hyaluronic acid-taurocholic acid (HA-TCA) conjugate. The HTsRP-NC promotes cell penetration and enhances endosomal escape in cancer cells. Moreover, protection of the sRP by HA-TCA from the hostile GI environment helps the AKT siRNA complex to reach the liver through the utilization of a TCA-mediated enterohepatic bile acid recycling system. AKT siRNA was released by 90% in presence of hyaluronidase in the tumor cells which indicate the potential use of HTsRP-NCs for siRNA delivery to treat tumor. After HA receptor (CD44)-mediated cellular uptake of the HTsRP-NC by the liver cancer cells, functional expression of AKT siRNA leads to the suppression of metastatic liver cancer growth in a colorectal liver metastasis (CLM) murine model. Tumor nodules were reduced by more than 1 mm size compared to control group and tumor cells were suppressed by 50% after HTsRP-NCs treatment with AKT siRNA. Overall, oral administration of the HTsRP-NC supports its potential in therapeutic applications for the effective treatment of CLM.

β-Catenin mRNA Silencing and MEK Inhibition Display Synergistic Efficacy in Preclinical Tumor Models

Colorectal carcinomas harbor well-defined genetic abnormalities, including aberrant activation of Wnt/β-catenin and MAPK pathways, often simultaneously. Although the MAPK pathway can be targeted using potent small-molecule drugs, including BRAF and MEK inhibitors, β-catenin inhibition has been historically challenging. RNAi approaches have advanced to the stage of clinical viability and are especially well suited for transcriptional modulators, such as β-catenin. In this study, we report therapeutic effects of combined targeting of these pathways with pharmacologic agents. Using a recently described tumor-selective nanoparticle containing a β-catenin-targeting RNAi trigger, in combination with the FDA-approved MEK inhibitor (MEKi) trametinib, we demonstrate synergistic tumor growth inhibition in in vivo models of colorectal cancer, melanoma, and hepatocellular carcinoma. At dose levels that were insufficient to significantly impact tumor growth as monotherapies, combination regimens resulted in synergistic efficacy and complete tumor growth inhibition. Importantly, dual MEKi/RNAi therapy dramatically improved survival of mice bearing colorectal cancer liver metastases. In addition, pharmacologic silencing of β-catenin mRNA was effective against tumors that are inherently resistant or that acquire drug-induced resistance to trametinib. These results provide a strong rationale for clinical evaluation of this dual-targeting approach for cancers harboring Wnt/β-catenin and MAPK pathway mutations. Mol Cancer Ther; 17(2); 544-53. ©2017 AACR.

Impact of associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) on growth of colorectal liver metastases

BACKGROUND

Associating liver partition and portal vein ligation for staged hepatectomy induces an unprecedented liver hypertrophy and enables resection of otherwise unresectable liver tumors. The effect of associating liver partition and portal vein ligation for staged hepatectomy on tumor proliferation, however, remains a concern. This study investigated the impact of associating liver partition and portal vein ligation for staged hepatectomy on growth of colorectal metastases in mice and in humans.

METHODS

The effect of associating liver partition and portal vein ligation for staged hepatectomy and 90% portal vein ligation on colorectal liver and lung metastases was investigated in mice. In vivo tumor progression was assessed by magnetic resonance imaging, histology, and survival experiments. The effects of associating liver partition and portal vein ligation for staged hepatectomy, portal vein ligation, and control sera on cultures of several colorectal cancer cell lines (MC38 and CT26) were tested in vitro. Additionally, the international associating liver partition and portal vein ligation for staged hepatectomy registry enabled us to identify patients with remaining tumor in the future liver remnant after associating liver partition and portal vein ligation for staged hepatectomy stage 1.

RESULTS

Two and 3 weeks after associating liver partition and portal vein ligation for staged hepatectomy stage 1, portal vein ligation, or sham surgery, liver magnetic resonance images showed similar numbers (P=.14/0.82), sizes (P=.45/0.98), and growth kinetics (P=.58/0.68) of intrahepatic tumor. Tumor growth was not different between the associating liver partition and portal vein ligation for staged hepatectomy and portal vein ligation groups after completion of stage 2. Median survival after tumor cell injection was similar after sham surgery (36 days; 95% confidence interval; 27-57 days), completion of associating liver partition and portal vein ligation for staged hepatectomy (42 days; 95% confidence interval; 35-49 days), and portal vein ligation (39 days; 95% confidence interval; 34-43 days, P=.237). Progression of pulmonary metastases and in vitro cell proliferation were comparable among groups. Observations in humans failed to identify any accelerated tumor growth in the future liver remnant within the regenerative phase after associating liver partition and portal vein ligation for staged hepatectomy stage 1.

CONCLUSION

The accelerated regeneration process associated with associating liver partition and portal vein ligation for staged hepatectomy does not appear to enhance growth of colorectal metastases.

Angiotensin II subtype 1a receptor signaling in resident hepatic macrophages induces liver metastasis formation

Liver metastases from colorectal cancer (CRC) are a clinically significant problem. The renin-angiotensin system is involved in tumor growth and metastases. This study was designed to evaluate the role of angiotensin II subtype receptor 1a (AT1a) in the formation of liver metastasis in CRC. A model of liver metastasis was developed by intrasplenic injection of mouse colon cancer (CMT-93) into AT1a knockout mice (AT1aKO) and wild-type (C57BL/6) mice (WT). Compared with WT mice, the liver weight and liver metastatic rate were significantly lower in AT1aKO. The mRNA levels of CD31, transforming growth factor- β1 (TGF-β1), and F4/80 were suppressed in AT1aKO compared with WT. Double immunofluorescence analysis showed that the number of accumulated F4/80+ cells expressing TGF-β1 in metastatic areas was higher in WT than in AT1aKO. The AT1aKO bone marrow (BM) (AT1aKO-BM)→WT showed suppressed formation of liver metastasis compared with WT-BM→WT. However, the formation of metastasis was further suppressed in WT-BM→AT1aKO compared with AT1aKO-BM→WT. In addition, accumulated F4/80+ cells in the liver metastasis were not BM-derived F4/80+ cells, but mainly resident hepatic F4/80+ cells, and these resident hepatic F4/80+ cells were positive for TGF-β1. Angiotensin II enhanced TGF-β1 expression in Kupffer cells. Treatment of WT with clodronate liposomes suppressed liver metastasis by diminishing TGF-β1+ F4/80+ cells accumulation. The formation of liver metastasis correlated with collagen deposition in the metastatic area, which was dependent on AT1a signaling. These results suggested that resident hepatic macrophages induced liver metastasis formation by induction of TGF-β1 through AT1a signaling.

Novel mouse models of hepatic artery infusion

BACKGROUND

The liver has unique anatomy in that most blood flow to normal hepatocytes is derived from the portal venous system, whereas liver tumors obtain their nutrient blood supply exclusively from the hepatic artery. The focused arterial delivery of anticancer agents to liver tumors has been performed for decades; however, preclinical models to standardize drug regimens and examine novel agents have been lacking. The purpose of this study was to establish preclinical hepatic artery infusion (HAI) models in a mouse and to evaluate the safety and delivery capability of the models.

MATERIAL AND METHODS

C57BL/6 and BALB/c mice were used to develop models of HAI via the hepatic artery (HA), superior pancreaticoduodenal artery (SPDA), or lienogastric artery (LGA). Success rates, distribution of perfusion, and associated morbidity and mortality were analyzed between groups.

RESULTS

All three models were feasible and reproducible in mice, and there was no statistical difference on body weight change between models. The HA model had a 13.3% mortality from acute liver failure, and the SPDA model demonstrated duodenal and pancreatic toxicity. SPDA and LGA routes had the highest success rates (96.7% and 91.4%, respectively) with low mortality, better drug delivery, and preserved physiologic liver function compared with the HA model.

CONCLUSIONS

The optimal route of HAI was mouse breed specific; SPDA access in BALB/c mice, and the LGA access in C57BL/6 mice. The described techniques serve as a reproducible platform for the identification and characterization of therapeutics for diverse metastatic liver tumors.

Statin and rottlerin small-molecule inhibitors restrict colon cancer progression and metastasis via MACC1

MACC1 (Metastasis Associated in Colon Cancer 1) is a key driver and prognostic biomarker for cancer progression and metastasis in a large variety of solid tumor types, particularly colorectal cancer (CRC). However, no MACC1 inhibitors have been identified yet. Therefore, we aimed to target MACC1 expression using a luciferase reporter-based high-throughput screening with the ChemBioNet library of more than 30,000 compounds. The small molecules lovastatin and rottlerin emerged as the most potent MACC1 transcriptional inhibitors. They remarkably inhibited MACC1 promoter activity and expression, resulting in reduced cell motility. Lovastatin impaired the binding of the transcription factors c-Jun and Sp1 to the MACC1 promoter, thereby inhibiting MACC1 transcription. Most importantly, in CRC-xenografted mice, lovastatin and rottlerin restricted MACC1 expression and liver metastasis. This is-to the best of our knowledge-the first identification of inhibitors restricting cancer progression and metastasis via the novel target MACC1. This drug repositioning might be of therapeutic value for CRC patients.

Macrophage migration inhibitory factor siRNA inhibits hepatic metastases of colorectal cancer cells

The purpose of this study was to assess the anti-tumor effects of macrophage migration inhibitory factor (MIF) siRNA on colorectal cancer in a mouse xenograft model. MIF specific siRNA (MIF siRNA) or a nonspecific control siRNA was introduced to murine colorectal cancer CT-26 cells. Mouse xenograft models of colorectal cancer were established. MIF siRNA, control siRNA or water was injected twice a week intravenously for 4 weeks. MIF siRNA inhibited the proliferation and migration, while induced apoptosis of CT-26 cells in vitro. Injection of MIF siRNA resulted in a significant decrease of serum MIF and VEGF levels, and the weight and volume of cecum-grafted tumors in vivo. In contrast, the number of apoptotic cells and caspase-3 expression were increased by MIF siRNA in cecum graft tumor tissues. Moreover, the water and fodder consumption were significantly improved by MIF siRNA treatment. Importantly, MIF siRNA reduced the hepatic metastases from colorectal cancer. Our results suggest that siRNA targeting MIF is a promising agent for the treatment of hepatic metastasis of colorectal cancer cells.

CHARACTERISTICS OF THYROID STATUS IN EXPERIMENTAL LIVER METASTASIS

Aim of the study was to analyze the dynamics of thyroid hormones in the pituitary gland, thyroid gland (TG) and blood serum (BS) in liver metastases to reveal thyroid profile of metastasis and to find thyroid markers-of metastasis in BS.

MATERIAL AND METHODS

The experiment included 44 white male rats weighing 180-250 g. Sarcoma 45 (S-45) was transplanted intrasplenically after the spleen was brought under the skin. Levels of thyroid hormones: thyroid stimulating hormone (TSH) in the pituitary gland, TG, BS; free (FT4) and total (T4) thyroxine and free (FT3) and total (T3) triiodothyronine in TG and BS were studied by radioimmunoassay (Immunotech, Czech Republic; Arian analyzer, Russia).

RESULTS

From the first days of the tumor development, pituitary gland strain with TSH hyperproduction was observed, and later TG hypofunctioning developed. Quantitative changes of thyroid hormones in organs did not correspond to their dynamics in BS. First diagnostic signs of experimental liver metastases, under the absence of formed metastases in the organ, were hyper-TSH-emy and the tendency to FT3 decreasing in BS. Typical characteristics of the "climax" of liver metastasis included formation of a marked "low TB" syndrome which transformed into a more severe "lowT3/lowT4" syndrome in secondary metastasis to the lungs.

CONCLUSIONS

Thus, primary tumor growth and development of metastases are accompanied by the strain and imbalanced functioning of the thyroid system. Analysis of dynamics of the thyroid axis hormones in BS allows prognosis of liver metastases, as well as contributes to identifying the point of no return for the disease development which leads to secondary metastasis and irreversible progression of the process.

Effect of preoperative administration of methylpredonisolone and ulinastatin on tumor cell metastasis after surgical stress

Using a rat laparotomy stress model, we conducted a comparative analysis of postoperative organ metastasis after administration of ulinastatin (UTI) or methylprednisolone (MP), which have an inhibitory effect on cytokine production. The subjects were classified into 4 groups: 1) minimal laparotomy group (C group), 2) major laparotomy group (L group), 3) preoperative MP intravenous administration + major laparotomy group (MP group), and 4) preoperative UTI intravenous administration + major laparotomy group (UTI group). Either MP or UTI was administered intravenously before surgery, and RI-labeled cells were injected into the portal vein immediately after laparotomy to collect tissue specimens in order to measure radiation dosage. Then, the concentrations of serum IL-2 and IL-6, liver interleukin 1 beta (IL-1β) and interleukin 10 (IL-10), and liver E-selectin were measured. In addition natural killer cell, (NK cell) activation and neoplastic nodules on the liver surface at 3 weeks after surgery were also measured. The adhesion rate of malignant cells to the liver was higher in the L group than in the C group, higher in the MP group than the L group, and lower overall in the UTI group. The concentration of IL-1β and IL-6 were decreased in the MP and UTI groups compared to the L group. IL-2 was decreased significantly in the MP group compared with the C and L groups. E-selectin expression level decreased in the UTI group compared with the L group. NK cell activation decreased in the MP group compared with the C group and L group, but no differences were observed between the UTI and L groups. The number of tumor nodules on the surface of the liver increased in the MP group compared with the L group, and decreased in the UTI group compared with the L group. Postoperative alleviation of invasive reaction was suggested in both the MP and UTI groups. However, preoperative administration of MP increased metastasis while that of UTI inhibited metastasis. MP was considered to have decreased anti-tumor immunocompetence and promoted metastasis, while UTI was considered to have inhibited the expression of adhesive molecules and decreased metastasis.

[Dynamics of growth factors in the spleen and liver of rats at different stages of metastatic hepatic reconstitution]

The aim--to study the dynamics of IGF-I, IGS-II, TGF-β1 in liver and spleen tissues from rats at different stages of liver metastases.

MATERIALS AND METHODS

We have designed a model of liver metastases in male rats. The content of growth factors was examined by ELISA at 1, 2 and 5 weeks of carcinogenesis in tissue of liver and tumors of spleen.

RESULTS

The content of growth factors increased in liver tissue at different stages of metastasis. The concentration of TGF-β, increased from the first to the fifth week of carcinogenesis. The level of IGF-I increased after 2 weeks of carcinogenesis. CONCLUSION. Pathogenetic moments of metastasis to the liver are the change of growth factors levels, indicating intensification of metastasis from 2 weeks of carcinogenesis and proliferation from 1 to 5 weeks.

[Local level of neoangiogenesis factors in dynamics of experimental metastatic process in liver]

The aim--to study the dynamics content of VEGF-A, VEGF-R1, EGF and EGF-R1 in liver and spleen tissues from rats at different stages of liver metastases.

MATERIALS AND METHODS

We have designed a model of liver metastases in male rats. The content of growth factors was examined by ELISA at 1, 2 and 5 weeks of carcinogenesis in tissue of liver and tumors of spleen.

RESULTS

The content of growth factors increased in liver tissue at different stages of metastasis. The concentration of VEGF-A increased gradually from the 1st to 5th week carcinogenesis. The concentration of VEGF-R1 increased after 2 weeks and decreased slightly after 5 weeks of carcinogenesis. The level of all components of EGF/EGF-R1 increased after 2 weeks of carcinogenesis.

CONCLUSION

The following pathogenetic aspects of liver metastasis were defined: change in levels of VEGF-A/VEGF-R1 indicating the progressive development of the process of neoangiogenesis, and increased levels of EGF/EGF-R1 responsible for metastasis processes.

Inhibitory effect of cordycepin on experimental hepatic metastasis of B16-F0 mouse melanoma cells

In a previous study performed by our group, we demonstrated that the water extract of Cordyceps sinensis (WECS) significantly prevented tumor metastasis from the spleen to the liver, using B16-F0 mouse melanoma cells as a model. In this study, we investigated the anti-metastatic activity of cordycepin (3'-deoxyadenosine), one of the components of WECS, using an identical model of mice injected with B16-F0 cells into the spleen. All mice inoculated with B16-F0 cells died due to liver metastases via the portal vein from the spleen. Control mice not administered cordycepin exhibited higher serum levels of alanine aminotransferase (ALT) due to damage to the liver by metastasized B16-F0 cells from the spleen, and survival times ranged from 17 to 22 days after tumor inoculation. Cordycepin was intraperitoneally administered to mice, and resulted in significantly lower serum ALT levels and longer survival times than those observed in control mice. Taken together, these results indicate that cordycepin may be the active ingredient in C. sinensis exerting an anti-metastatic effect, and may be a potential candidate anti-metastatic agent.

Hepatic arterial infusion of temsirolimus inhibits tumor growth of colorectal rat liver metastases even after a growth stimulating procedure like liver resection

BACKGROUND

Hepatic arterial infusion (HAI) of specific anti-tumor drugs can be more effective compared with systemic drug application. Herein, we studied whether HAI of temsirolimus is effective to inhibit tumor growth of colorectal liver metastases after liver resection.

MATERIALS AND METHODS

Twenty-four Wistar Albino Glaxo from Rijswijk (WAG/Rij) rats were randomized to four groups and underwent subcapsular implantation of CC531 colorectal cancer cells in the left liver lobe. In two groups, a 70% liver resection (Phx) was performed simultaneously. After 10 d, animals received either a HAI of temsirolimus (CCI-779) or saline solution (controls). Tumor growth was determined on d 10 and 13 using three-dimensional ultrasound. On d 13, tumor tissue was removed for histologic and immunohistochemical analysis.

RESULTS

Sham controls revealed a tumor growth of ∼40% from d 10 to d 13. HAI of temsirolimus completely inhibited this tumor growth. Controls with Phx showed a tumor growth of >60%. In contrast, HAI of temsirolimus in Phx animals did not only inhibit tumor growth but was even capable of decreasing the tumor size by ∼8%. Immunohistochemical analysis of the tumors showed a decreased proliferation rate and an increased cleaved caspase-3 activity, which was associated with a significant reduction of platelet endothelial cell adhesion molecule (PECAM)-1-positive cells after HAI of temsirolimus.

CONCLUSIONS

HAI of temsirolimus inhibits tumor growth of CC531 colorectal liver metastases even if a growth-stimulating procedure like Phx is performed. Inhibition of tumor growth is provided by a decrease of tumor vascularization associated with an inhibition of tumor cell proliferation and an induction of tumor cell apoptosis.

A CD90(+) tumor-initiating cell population with an aggressive signature and metastatic capacity in esophageal cancer

Tumor-initiating cells (TIC), also known as cancer stem cells, are regarded widely as a specific subpopulation of cells needed for cancer initiation and progression. TICs have yet to be identified in esophageal tumors that have an increasing incidence in developed countries. Here, we report a CD90(+) cell population found in esophageal squamous cell carcinoma (ESCC), which is endowed with stem cell-like properties and high tumorigenic and metastatic potential. mRNA profiling of these cells suggested pathways through which they drive tumor growth and metastasis, with deregulation of an Ets-1/MMP signaling pathway and epithelial-mesenchymal transition figuring prominently. These cells possessed higher self-renewal activity and were sufficient for tumor growth, differentiation, metastasis, and chemotherapeutic resistance. CD90(+) TICs were isolated and characterized from ESCC clinical specimens as well as ESCC cell lines. In freshly resected clinical specimens, they represented a rare cell population, the levels of which correlated with strong family histories and lymph node metastasis. Our results prompt further study of this CD90(+) population of esophageal TICs as potential therapeutic targets.

Sex-dependent liver colonization of human melanoma in SCID mice--role of host defense mechanisms

The possibility that endocrine factors may influence the clinical course of malignant melanoma is suggested by the superior survival data of women. In preclinical models we observed a higher rate of colony formation by human melanoma cells in male compared to female SCID mice, but only in the case of the liver and not in other organs. The gender difference could be seen at an early phase of colony formation. On the other hand, in our human melanoma cell lines we failed to detect steroid receptor protein expression, and treatment with sex hormones did not considerably influence their in vitro behavior. Investigating the possible contribution of host cells to the observed gender difference, we performed in vivo blocking experiments applying pretreatment of the animals with Kupffer cell inhibitor gadolinium chloride and the NK cell inhibitor anti-asialo GM1 antibody. While Kupffer cell blockade enhanced melanoma liver colonization equally in the two sexes, a more prominent increase was observed in female than in male mice in the case of NK cell inhibition. Further supporting the importance of NK cells in the lower liver colonization efficiency of melanoma cells in females, gender difference in colony formation was lost in NSG mice lacking NK activity. Although in humans no organ selectivity of gender difference in melanoma progression has been observed according to data in the literature, our results possibly indicate a contribution of natural host defense mechanisms to gender difference in survival of patients with melanoma or other tumor types as well.

Activation of vagus nerve by semapimod alters substance P levels and decreases breast cancer metastasis

Chronic inflammation is involved in initiation as well as in progression of cancer. Semapimod, a tetravalent guanylhydrazon and formerly known as CNI-1493, inhibits the release of inflammatory cytokines from activated macrophages and this effect is partly mediated by the vagus nerve. Our previous findings demonstrated that inactivation of vagus nerve activity as well sensory neurons enhanced visceral metastasis of 4THM breast carcinoma. Hence semapimod by activating vagus nerve may inhibit breast cancer metastasis. Here, effects of semapimod on breast cancer metastasis, the role of vagal sensory neurons on this effect and changes in mediators of the neuroimmune connection, such as substance P (SP) as well as neprilysin-like activity, were examined. Vagotomy was performed on half of the control animals that were treated with semapimod following orthotopic injection of 4THM breast carcinoma cells. Semapimod decreased lung and liver metastases in control but not in vagotomized animals with an associated increased SP levels in sensory nerve endings. Semapimod also increased neprilysin-like activity in lung tissue of control animals but not in tumor-bearing animals. This is the first report demonstrating that semapimod enhances vagal sensory nerve activity and may have anti-tumoral effects under in-vivo conditions. Further studies, however, are required to elucidate the conditions and the mechanisms involved in anti-tumoral effects of semapimod.

Inhibiting systemic autophagy during interleukin 2 immunotherapy promotes long-term tumor regression

Administration of high-dose interleukin-2 (HDIL-2) has durable antitumor effects in 5% to 10% of patients with melanoma and renal cell carcinoma. However, treatment is often limited by side effects, including reversible, multiorgan dysfunction characterized by a cytokine-induced systemic autophagic syndrome. Here, we hypothesized that the autophagy inhibitor chloroquine would enhance IL-2 immunotherapeutic efficacy and limit toxicity. In an advanced murine metastatic liver tumor model, IL-2 inhibited tumor growth in a dose-dependent fashion. These antitumor effects were significantly enhanced upon addition of chloroquine. The combination of IL-2 with chloroquine increased long-term survival, decreased toxicity associated with vascular leakage, and enhanced immune cell proliferation and infiltration in the liver and spleen. HDIL-2 alone increased serum levels of HMGB1, IFN-γ, IL-6, and IL-18 and also induced autophagy within the liver and translocation of HMGB1 from the nucleus to the cytosol in hepatocytes, effects that were inhibited by combined administration with chloroquine. In tumor cells, chloroquine increased autophagic vacuoles and LC3-II levels inhibited oxidative phosphorylation and ATP production and promoted apoptosis, which was associated with increased Annexin-V(+)/propidium iodide (PI)(-) cells, cleaved PARP, cleaved caspase-3, and cytochrome c release from mitochondria. Taken together, our findings provide a novel clinical strategy to enhance the efficacy of HDIL-2 immunotherapy for patients with cancer.

Darbepoetin-α promotes neovascularization and cell proliferation in established colorectal liver metastases

BACKGROUND

The erythropoietin-analogue darbepoetin-α (DPO) improves liver function and regeneration after hepatectomy (Phx), however, also enhances Phx-induced tumor cell engraftment and neovascularization. Because it is unknown whether DPO also enhances the growth of established tumors, we herein studied the effect of DPO on established colorectal liver metastases after Phx.

METHODS

CT26.WT cells were implanted into the liver of BALB/c mice. Five days after tumor establishment, animals underwent 50% Phx and received 10 μg/kgBW DPO or saline. Non-Phx animals with DPO or saline-treatment served as controls. Seven days after Phx tumors were analyzed regarding blood vessel formation, leukocyte adhesion, cell proliferation, apoptotic cell death, and growth using intravital fluorescence microscopy, histology, and immunohistochemistry.

RESULTS

The growth of established colorectal liver metastases was slightly stimulated after DPO-treatment in hepatectomized and non-hepatectomized animals. However, tumor vessel formation and tumor cell proliferation were significantly enhanced after DPO-treatment in hepatectomized and non-hepatectomized mice compared with controls. Apoptotic cell death and leukocyte-endothelial cell interaction were significantly reduced after DPO-treatment.

CONCLUSION

Our study indicates that DPO-treatment promotes neovascularization and cell proliferation in established colorectal liver metastases of hepatectomized and non-hepatectomized mice. DPO-application in patients with colorectal liver metastases might promote tumor progression and should therefore be avoided.

The protective effect of Schisandra lignans on stress-evoked hepatic metastases of P815 tumor cells in restraint mice

AIM OF THE STUDY

The present study was conducted to investigate the effects of schisandra lignans extract (SLE) on stress-evoked hepatic metastases of mastocytoma P815 tumor cells, which was closely related with immune function.

MATERIALS AND METHODS

The high-performance liquid chromatography (HPLC) fingerprint of SLE was recorded and the percentage composition of schisandra lignans was determined as 82.63%. The contributions of the immunomodulatory properties of SLE to the protective effects on stress-induced hepatic metastases were studied.

RESULTS

Our results found that restraint stress significantly promoted hepatic metastases of P815 tumor cells. However, oral administration of SLE (100 and 200mg/kg/d, 14d) significantly reduced the number of metastatic colonies in liver of restrained mice. SLE was further found to be significantly improving T lymphocyte proportions and increasing cytotoxic T lymphocyte (CTL) activity of immunized spleen cells in stressed mice.

CONCLUSION

These results indicated that the protective effects of SLE on hepatic metastases were related to its alleviation of the adverse effects of stressors for bio-homeostasis and immunoprotection. The obtained data provided evidences to elucidate the traditional use of Fructus schisandrae as a tonic or sedative.

Enhanced anti-cancer effect of 5-fluorouracil loaded into thermo-responsive conjugated linoleic acid-incorporated poloxamer hydrogel on metastatic colon cancer models

Conjugated linoleic acid-coupled Pluronic F127 (Plu-CLA) is an effective drug delivery system with numerous advantages and anti-cancer activity. 5-FU administered in Plu-CLA hydrogel (P-FU) led to the significant enhancement of tumor growth suppression and cellular apoptosis. Moreover, growth of hepatic and intraperitoneal metastases in vivo was significantly reduced in mice treated with P-FU. Therefore, Plu-CLA could be a potential intraperitoneal carrier for hydrophilic 5-FU for the effective treatment of metastatic colon cancer.

Hepatic arterial infusion in the treatment of liver metastases with PEG liposomes in combination with degradable starch microspheres (DSM) increases tumor 5-FU concentration. an animal study in CC-531 liver tumor-bearing rats

The regional application of cytostatics in liver metastases leads to increased concentrations in the tumor tissue. The effect of flow retardation by temporary occlusion and drug targeting with liposome encapsulation (PEG liposomes) on tumor 5-fluorouracil (5-FU) concentrations was investigated.

MATERIALS AND METHODS

Tumor-bearing rats were submitted to i.v. or intraarterial (i.a.) therapy with liposome-encapsulated or non-encapsulated 5-FU. The i.a. groups were additionally treated with or without Spherex® degradable starch microspheres (DSM). The tumor 5-FU concentrations were determined by high-performance liquid chromatography (HPLC) as area under the curve (AUC).

RESULTS

A comparison with i.v. in administered 5-FU yielded the following increases tumor concentrations: 5-FU-PEG liposomes i.v. 27-fold, 5-FU i.a. 19-fold, 5-FU i.a. + DSM 1760-fold, 5-FU-PEG liposomes i.a. 110-fold, 5-FU-PEG liposomes i.a. + DSM 7665-fold.

CONCLUSION

Liver intratumoral 5-FU concentration increases to >7,500 times that following i.v. administration by a combination of regional administration via the hepatic artery with temporary embolization by DSM and drug targeting by liposome-encapsulated 5-FU.

A novel combination treatment of armed oncolytic adenovirus expressing IL-12 and GM-CSF with radiotherapy in murine hepatocarcinoma

In this study, a novel combination treatment of armed oncolytic adenovirus expressing interleukin 12 (IL-12) and granulocyte-macrophage colony-stimulating factor (GM-CSF) with radiation was investigated for antitumor and antimetastatic effect in a murine hepatic cancer (HCa-I) model. Tumor bearing syngeneic mice were treated with radiation, armed oncolytic virus Ad-ΔE1Bmt7 (dB7) expressing both IL-12 and GM-CSF (armed dB7), or a combination of both. The adenovirus was administered by intratumoral injection 1 × 10(8) PFU per tumor in 50 µl of PBS four times every other day. Tumor response to treatment was determined by a tumor growth delay assay. Metastatic potential was evaluated by a lung metastasis model. To understand the underlying mechanism, the level of apoptosis was examined as well as the change in microvessel density and expression of immunological markers: CD4+, CD8+ and Cd11c. The combination of armed dB7 and radiation resulted in significant growth delay of murine hepatic cancer, HCa-1, with an enhancement factor of 4.3. The combination treatment also resulted in significant suppression of lung metastasis. Increase of apoptosis level as well as decrease of microvessel density was shown in the combination treatment, suggesting an underlying mechanism for the enhancement of antitumor effect. Expression of immunological markers: CD4+, CD8+ and Cd11c also increased in the combination treatment. This study showed that a novel combination treatment of radiotherapy with armed oncolytic adenovirus expressing IL-12 and GM-CSF was effective in suppressing primary tumor growth.

Improvement of biodistribution with PEGylated liposomes containing docetaxel with degradable starch microspheres for hepatic arterial infusion in the treatment of liver metastases: a study in CC-531 liver tumor-bearing WAG RIJ rats

AIM

To improve the drug concentration in liver metastases, docetaxel was encapsulated in polyethyleneglycol-liposomes and administered regionally with degradable starch microspheres (DSM).

MATERIALS AND METHODS

A rodent model of solitary metastasis (CC-531 adenocarcinoma) was studied. The animals were randomized into six groups and treated with 15 ng/kg docetaxel: I: intravenous (i.v.). II: PEG-liposomes i.v.; III: intraartial (i.a.) via the hepatica artery; IV: i.a.) + DSM; V: PEG-liposomes i.a.; and VI: PEG-liposomes i.a. + DSM. The docetaxel concentration in the serum, liver and liver tumor at defined times (5, 15, 30, 60,120 240 min and 24 h) was measured using HPLC.

RESULTS

The area under the concentration (AUC) versus time curves showed an 11-fold higher concentration in the tumor tissue when comparing the docetaxel-PEG-liposomes i.a. + DSM group to the i.v. group (p<0.01).

CONCLUSION

Compared to intravenous therapy, i.a. therapy with docetaxel-PEG-liposomes + DSM results in higher tumor tissue concentrations.

Rapid extravasation and establishment of breast cancer micrometastases in the liver microenvironment

To examine the interplay between tumor cells and the microenvironment during early breast cancer metastasis, we developed a technique for ex vivo imaging of murine tissue explants using two-photon microscopy. Cancer cells in the liver and the lung were compared by imaging both organs at specific time points after the injection of the same polyomavirus middle T-initiated murine mammary tumor cell line. Extravasation was greatly reduced in the lung compared with the liver, with 56% of tumor cells in the liver having extravasated by 24 hours, compared with only 22% of tumor cells in the lung that have extravasated. In the liver, imaged cells continually transitioned from an intravascular location to an extravascular site, whereas in the lung, extravasation rates slowed after 6 hours. Within the liver microenvironment, the average size of the imaged micrometastatic lesions increased 4-fold between days 5 and 12. Histologic analysis of these lesions determined that by day 12, the micrometastases were heterogeneous, consisting of both tumor cells and von Willebrand factor-positive endothelial cells. Further analysis with intravenously administered lectin indicated that vessels within the micrometastatic tumor foci were patent by day 12. These data present the use of two-photon microscopy to directly compare extravasation times in metastatic sites using the same tumor cell line and highlight the differences in early events and metastatic patterns between two important secondary sites of breast cancer progression with implications for future therapy.

Siah2-dependent concerted activity of HIF and FoxA2 regulates formation of neuroendocrine phenotype and neuroendocrine prostate tumors

Neuroendocrine (NE) phenotype, seen in >30% of prostate adenocarcinomas (PCa), and NE prostate tumors are implicated in aggressive prostate cancer. Formation of NE prostate tumors in the TRAMP mouse model was suppressed in mice lacking the ubiquitin ligase Siah2, which regulates HIF-1alpha availability. Cooperation between HIF-1alpha and FoxA2, a transcription factor expressed in NE tissue, promotes recruitment of p300 to transactivate select HIF-regulated genes, Hes6, Sox9, and Jmjd1a. These HIF-regulated genes are highly expressed in metastatic PCa and required for hypoxia-mediated NE phenotype, metastasis in PCa, and the formation of NE tumors. Tissue-specific expression of FoxA2 combined with Siah2-dependent HIF-1alpha availability enables a transcriptional program required for NE prostate tumor development and NE phenotype in PCa.

Insulin-like growth factor-I regulates the liver microenvironment in obese mice and promotes liver metastasis

Among the mechanisms implicated in the tumor-promoting effects of obesity, signaling by insulin-like growth factor-I (IGF-I) and insulin has received considerable attention. However, the emerging realization that obesity is associated with chronic inflammation has prompted other consideration of how the IGF-I axis may participate in cancer progression. In the present study, we used two mouse models of chronic (LID) and inducible (iLID) igf-1 gene deficiency in the liver to investigate the role of IGF-I in regulating the host microenvironment and colorectal carcinoma growth and metastasis in obese mice. Obese mice had a heightened inflammatory response in the liver, which was abolished in mice with chronic IGF-I deficiency (LID). In control animals changes to the hepatic microenvironment associated with obesity sustained the presence of tumor cells in the liver and increased the incidence of hepatic metastases after intrasplenic/portal inoculation of colon carcinoma cells. These changes did not occur in LID mice with chronic IGF-1 deficiency. In contrast, these changes occurred in iLID mice with acute IGF-1 deficiency, in the same manner as the control animals, revealing a fundamental difference in the nature of the requirement for IGF-1 on tumor growth and metastasis. In the setting of obesity, our findings imply that IGF-1 is critical to activate and sustain an inflammatory response in the liver that is needed for hepatic metastasis, not only through direct, paracrine effect on tumor cell growth, but also through indirect effects involving the tumor microenvironment.

Animal model of metastatic pheochromocytoma: evaluation by MRI and PET

OBJECTIVE

The development of metastatic pheochromocytoma animal model provides a unique opportunity to study the physiology of these rare tumors and to evaluate experimental treatments. Here, we describe the use of small animal imaging techniques to detect, localize and characterize metastatic lesions in nude mice.

METHODS

Small animal positron emission tomography (PET) imaging and magnetic resonance imaging (MRI) were used to detect metastatic lesions in nude mice following intravenous injection of mouse pheochromocytoma cells. [18F]-6-fluoro-dopamine ([18F]-DA) and [18F]-L-6-fluoro-3,4-dihydroxyphenylalanine, which are commonly used for localization of pheochromocytoma lesions in clinical practice, were selected as radiotracers to monitor metastatic lesions by PET.

RESULTS

MRI was able to detect liver lesions as small as 0.5mm in diameter. Small animal PET imaging using [18F]-DA and [18F]-DOPA detected liver, adrenal gland, and ovarian lesions.

CONCLUSION

We conclude that MRI is a valuable technique for tumor growth monitoring from very early to late stages of tumor progression and that animal PET confirmed localization of metastatic pheochromocytoma in liver with both radiotracers.

[Influence of liver regeneration after partial hepatectomy on the development of liver metastasis of colon cancer in rats]

OBJECTIVE

To investigate the stimulated effect of liver regeneration on colon cancer cells in remnant liver in rats.

METHODS

Rat models with liver metastases or retro-peritoneal metastases of colon cancer were established: animals underwent 37% or 70% liver resection and were compared with a sham laparotomy (15, 25, 15 cases, respectively). Metastases were performed two weeks before resection. Rats were killed 3 weeks after the resection. Total body weight, liver and tumor weights were recorded. The human colon adenocarcinoma cell line Lovo was cultured in the presence of portal serum withdrawn 24 hours and 14 days after partial hepatectomy (PH). DNA synthesis was assessed by flow cytometry analysis for 5-Bromodeoxyuridine (5-BrdU) incorporation.

RESULTS

The tumor growth was accelerated in the remnant liver in 70% PH group, but the tumors in 37% PH group and retro-peritoneal site were not influenced by PH. Compared with the control group, after cultured 72 hours with portal serum withdrawn 24 h after PH, a higher 5-BrdU incorporation was found in the Lovo cell lines (P < 0.05), and it reached the peak after 120 hours of culture (P < 0.05). No difference was found between the groups when cultured with the portal serum withdrawn 14 d after PH (P > 0.05).

CONCLUSIONS

PH may accelerate the growth of residual microscopic tumor in the liver which contributes to local recurrence. It has no systemic effect and effects on the cancer cell lines in extrahepatic sites. The excision extension is related to the stimulating effects on the cancer cell line, and subtotal hepatectomy is presumably a major determinant.

[Effect of stromal cell-derived factor-1 and its receptor CXCR4 on liver metastasis of human colon cancer]

OBJECTIVE

To investigate the effect of chemokine stromal cell-derived factor-1 (SDF-1) and its receptor CXCR4 on liver metastasis of human colon cancer.

METHODS

Expression of CXCR4 in different colon cancer cell lines and SDF-1 in different tissues were detected by using Western-blot technique. Effect of SDF-1 and anti-CXCR4 monoclonal antibody (McAb) on proliferation and migration of HT-29 cells were measured using MTT methods. Model mimicking liver metastasis of human colon cancer was established by injecting HT-29 cells intrasplenically into BALB/C nude mice. Mice were randomly divided into AMD3100 treated group and control group. Liver metastatic rate and tumor foci were measured 7 weeks after.

RESULTS

HT-29 cells expressed higher level of CXCR4 protein, and liver tissue expressed higher level of SDF-1 protein. Compared with the control, SDF-1 could significantly induced the proliferation and migration of the HT-29 cells, and anti-CXCR4 McAb could inhibited both functions of SDF-1. The liver metastasis rate in the control group was 100%, and it was 40% in the AMD3100 treating group (P < 0.05). The mean liver metastasis number also significantly decreased by AMD3100 (7.8 +/- 2.6 vs 22.4 +/- 8.6, P < 0.05).

CONCLUSIONS

SDF-1/CXCR4 biological axis play an important role in liver metastasis of human colon cancer. Arrest of CXCR4 can inhibit liver metastasis of colon cancer through blocking cell proliferation and migration induced by SDF-1.

Effect of splenectomy on antitumor immune system in mice

BACKGROUND

The influence on the antitumor immune system after splenectomy in vivo are controversial. CD4+CD25+Foxp3+T-cells (regulatory T-cell: reg T) and natural killer (NK) cells play important roles in immunological tolerance and antitumor immunity. The influence of splenectomy on the antitumor immune system was evaluated in a metastasis induced mouse model.

MATERIALS AND METHODS

Experiment 1, splenectomy in a cancer-free model. The mice were divided into two groups, one control, and the other splenectomy group. At days 4, 7 and 10 after splenectomy, the mesenteric lymph node, the liver and the lung were harvested. The lymph nodes were analyzed by flow cytometric analysis and the number of reg T-cells and NK cells were calculated. Foxp3 mRNA in the liver and the lung was evaluated by reverse transcriptional polymerase chain reaction (RT-PCR). Experiment 2, splenectomy in a liver metastasis model. Colon 26 cells were injected into the spleen of mice and the mice were divided into two groups, a spleen preserved group, and a splenectomy group. Splenectomy was performed at day 4 after injection. At days 7 and 10 after injection, flow cytometric analysis, and at day 10 RT-PCR were performed. Ten days after injection, the number of liver metastases (>1 mm) was counted.

RESULTS

Experiment 1, in the splenectomy group the flow cytometric analysis showed a significant decrease in the number of reg T and NK cells in the mesenteric lymph nodes compared with the control group. In the splenectomy group, the Foxp3 mRNA increased significantly in the liver at day 10, and in the lung at days 4 and 7. Experiment 2, liver metastasis was observed in the splenectomy group. Flow cytometric analysis showed that splenectomy did not affect the number of reg T at day 7 and day 10. The number of NK cells increased in the splenctomy group at day 7, but at day 10, there was no significant difference between the groups. RT-PCR showed that at day 10, the Foxp3 mRNA in liver increased in the splenectomy group.

CONCLUSION

The spleen plays a very important role in the antitumor immune system and splenectomy enhances liver metastasis through the increase of Foxp3 mRNA in the liver.

Pioglitazone, a ligand for peroxisome proliferator-activated receptor-gamma acts as an inhibitor of colon cancer liver metastasis

BACKGROUND

Peroxisome proliferator-activated receptor-gamma (PPARgamma) is a member of the steroid receptor superfamily. Liganded PPARgamma can inhibit cancer cell proliferation. The in vitro and in vivo inhibitory effect of the synthetic ligands, ciglitazone (CGZ) and pioglitazone (PGZ), on human colon cancer was investigated.

MATERIALS AND METHODS

Cell proliferation and the expression of PPARgamma, cyclooxygenase (COX)-2 and cyclin D1 were assessed in colon cancer cells treated with CGZ or PGZ. After subcutaneous or splenic inoculation of severe combined immunodeficient (SCID) mice using colon cancer HT-29 and SW480 cells, PGZ was administered orally and tumor growth inhibition was assessed by xenograft volume. The COX-2, cyclin D1 and PPARgamma expression in the HT-29 cells was evaluated.

RESULTS

Cultured HT-29 and SW480 cells expressed PPARgamma and proliferation was inhibited by CGZ and PGZ. Oral PGZ inhibited xenograft tumor growth and liver metastases in the SCID mouse and suppressed expression of COX-2 and cyclin D1 in HT-29 cells.

CONCLUSION

PGZ down-regulates COX-2 and cyclin D1 and inhibits colon cancer proliferation and liver metastasis, making PPARgamma a candidate target for the treatment/prevention of colon cancer metastasis.

Suppression of growth and hepatic metastasis of murine B16FO melanoma cells by a novel nutrient mixture

Highly metastatic melanoma is resistant to existing therapies. Our main objective was to investigate the effect of a nutrient mixture (NM) on B16FO tumor growth and hepatic metastasis. Tumor growth was studied in athymic nude male mice, 5-6 weeks old, inoculated with 10(6) B16FO melanoma cells subcutaneously and fed either a regular diet or one supplemented with 0.5% NM. Four weeks later, the mice were sacrificed and their tumors excised, weighed and processed for histology. Metastasis was studied in C57BL/6 mice, which received 10(6) B16FO melanoma cells by intrasplenic injection, as well as a regular or 0.5% NM-supplemented diet for 2 weeks. Survival was studied in C57BL/6 mice receiving 10(6) B16FO melanoma cells intraperitoneally (i.p.) followed by the regular, NM-supplemented, or regular diet in addition to being administered with 2 mg NM injection 3 times per week. NM inhibited the growth of B16FO melanoma cells by 50%. Lesions in the two groups were consistent with malignant melanoma. Mice were injected with B16FO cells in the spleen. Those fed the regular diet developed large black spleens and livers indicating growth in the spleen and metastasis to the liver. In contrast, mice supplemented with NM showed less growth in spleen, but also reduced metastasis to the liver. The survival time of mice receiving NM supplementation and B16FO cells i.p. was greater than in mice which were fed the regular diet. To confirm effects in vivo, we investigated the effect of NM on murine B16FO melanoma cells in vitro, including cell proliferation by MTT assay, morphology by hematoxylin and eosin (H&E) staining and apoptosis using live green caspase detection kit. In vitro, NM was not toxic at 100 microg/ml concentration, but exhibited 44% toxicity over the control at 500 and 1000 microg/ml. H&E did not indicate any changes up to 100 microg/ml. NM induced slight apoptosis at 100 microg/ml, moderate at 500 and extensive at 1000 microg/ml concentration.

Immunogene therapy by adenovirus vector expressing CD40 ligand for metastatic liver cancer in rats

BACKGROUND

We have explored a gene-therapeutic approach to stimulate antitumor immunity by adenoviral-mediated transfer of CD40 ligand (CD40L) to treat metastatic liver cancer in a rat model.

MATERIALS AND METHODS

Rat metastatic liver cancer cells were implanted into the back of rats bilaterally. When the larger tumor reached 8.0 mm in diameter, adenovirus vector-expressing mouse CD40L was injected intratumorally as treatment group (n=5), while LacZ was injected in the control group (n=5).

RESULTS

In the control group, the tumor gradually grew to be 20.7+/-1.6 (mean+/-SD) mm in intratumorally injected tumors and 21.8+/-3.7 mm in opposite tumors seven weeks after injection, respectively. In contrast, in the treatment group, the tumor was reduced to 3.6+/-8.2 mm and 3.7+/-8.2 mm. The tumor growth and survival rate were significantly different (p<0.001).

CONCLUSION

Adenovirus vector-mediated CD40L gene therapy is an effective therapeutic method for metastatic liver cancer.

Vascular targeting agent Oxi4503 inhibits tumor growth in a colorectal liver metastases model

BACKGROUND AND AIM

Oxi4503 is a potent vascular targeting agent belonging to the family of combretastatins. These agents produce an acute reduction in tumor blood flow leading to tumor necrosis. Despite evidence of its efficacy in certain malignancies, the effect on colorectal liver metastases remains largely unknown. This study investigates the effect of Oxi4503 on colorectal liver metastases in a murine model.

METHODS

The effect of a single dose of Oxi4503 on established tumors in a murine model of colorectal liver metastases was assessed following administration of 1-50 mg/kg Oxi4503. In addition, the effects of continuous, daily and intermittent dosing (1-5 mg/kg) on tumor necrosis and growth were studied by quantitative histological and stereological analysis. The effect of multiple dosing on long-term survival was also assessed using the Kaplan-Meier analysis. The microvascular effects of therapy were studied by scanning electron microscopy of microvascular resin casts.

RESULTS

A single dose of 5 or 50 mg/kg of Oxi4503 produced significant tumor necrosis compared to the controls. Subcutaneous continuous dosing infusion with Oxi4503 at 1 mg/kg/day reduced tumor growth compared to the controls, but was associated with marked systemic toxicity. Daily administration over 21 days was associated with significant mortality. Intermittent dosing of Oxi4503 (two doses, 3 days apart) produced the greatest reduction in tumor growth with minimal toxicity and conferred a significant survival advantage. Microvascular casts demonstrated significant disruption of tumor vessels.

CONCLUSIONS

A single dose of Oxi4503 produced significant necrosis and microvascular injury in colorectal liver metastases. Intermittent dosing with Oxi4503 produced the maximum reduction in tumor growth, minimal toxicity, and a significant improvement in survival. Oxi4503 is a potential anticancer agent. Further research into its mechanism of action and its synergistic use with other therapies is warranted.

Establishment of combined immuno-chemotherapy with systemically administered gemcitabine and intra-portal administration of interleukin-2 in murine models of liver metastases of pancreatic cancer

Despite attempts to use multiple drug combinations that include gemcitabine (GEM), there is very little evidence that these combination regimens are superior to the single use of this agent. We therefore investigated the suppressive effect of the combination of systemically administered GEM and locally administered interleukin-2 (IL-2) on liver metastasis in pancreatic cancer. Tumor-bearing mice were randomly divided into four groups: a control group, an IL-2 intrasplenic (is) administration group, a GEM intraperitoneal (ip) administration group, and a GEM ip+IL-2 is group. Liver weight, liver metastases, and tumor diameter (as assessed by the Winn assay) were compared among groups. Liver weight was significantly lower in the GEM+IL-2 group than in the control and IL-2 groups. The number of liver metastases was significantly reduced in the GEM+IL-2 group compared with all other groups. Splenocyte production of interferon-gamma increased significantly in the GEM+IL-2 group after stimulation with Concanavalin A. Furthermore, tumor diameter was significantly reduced in the GEM+IL-2 group in the Winn assay when compared to that of the control group. These findings suggest that a combined regimen of GEM and portally administrated IL-2 might prevent liver metastasis in pancreatic cancer patients more effectively than current approaches and could prove useful as a postsurgical adjuvant therapeutic.

[Establishment of nude mice liver metastatic model of human primary malignant melanoma of the small intestine]

OBJECTIVE

To provide ideal animal models for exploring pathogenesis and experimental therapy of primary malignant melanoma of the small intestine.

METHODS

The histologically intact primary and liver metastatic fragments derived from surgical specimens of one patient with metastatic malignant melanoma of the small intestine were orthotopically implanted in the small intestinal mucous layer of nude mice. The take rate, invasion and liver metastasis were observed. Morphology (light microscopy, electron microscopy), immunophenotype analysis, flow cytometry and karyotype analysis were applied for the original human tumors and the transplanted tumors.

RESULTS

The primary and liver metastatic fragments of malignant melanoma of the small intestine were successfully implanted in nude mice. After continuous passages in nude mice,an orthotopic model of human primary malignant melanoma of the small intestine(from the primary focus)in nude mice (termed HSIM-0501) and a liver metastatic model of human primary malignant melanoma of the small intestine (from the liver metastatic focus) in nude mice (termed HSIM-0502) were established. Histological examination of transplanted tumors revealed high-grade melanoma. S-100 protein and HMB45 were positive. Massive melanin granules and melanin complex were seen in cytoplasm of tumor cells.Chromosomal modal number was between 55 and 59. DNA index (DI) was 1.49-1.61, representing heteroploid. HSIM-0501 and HSIM-0502 were maintained for 25 and 27 passages in nude mice respectively. Three hundred and seventeen nude mice were used for transplantation. Both the take rate after transplantation and resuscitation rate of liquid nitrogen cryopreservation were 100%. HSIM-0501 exhibited 46.2% liver metastasis and 36.7% lymph node metastases. In HSIM-0502, both liver and lymph node metastases were 100%.The transplanted tumors autonomically and invasively grew in the small intestines of nude mice and hematogenous metastasis, lymph node metastasis and celiac planting metastasis occurred.

CONCLUSION

Two nude mice liver metastatic models of human primary malignant melanoma of the small intestine are successfully established, which provide ideal animal models for the research of pathogenesis,metastasis biology and anti-metastatic experimental therapy of primary malignant melanoma of the small intestine.

Nutrient mixture including vitamin C, L-lysine, L-proline, and epigallocatechin is ineffective against tumor growth and metastasis in a syngeneic neuroblastoma model

BACKGROUND

The replacement of established evidence-based cancer therapy protocols (mainstream therapy) by unevaluated complementary and alternative medicine (CAM) is a challenge in pediatric oncology. We tested the hypothesis that oral application of L-lysine and ascorbic acid (Lysin C Drink) in combination with epigallocatechin-gallate (EGCG) and amino-acids (Epican forte) is effective in a preclinical model of neuroblastoma.

METHODS

Primary tumors and spontaneous metastases were induced in A/J mice by injection of NXS2 neuroblastoma cells. Mice were treated by daily oral gavage with L-lysine and ascorbic acid (Lysin C Drink) (equivalent to 150 mg ascorbic acid/day/mouse) (treatment A) or with EGCG plus ascorbic- and amino-acids (Epican forte) (9.2 mg/mouse) (treatment B). Treatment A was started in the prophylactic setting (7 days before tumor cell injection) as well as in the therapeutic setting (1 day after tumor cell inoculation). Finally, treatment B was evaluated alone and in combination with treatment A in the therapeutic setting. The effect on primary tumor growth and the development of spontaneous liver metastases was evaluated.

RESULTS

L-lysine and ascorbic acid (Lysin C Drink) and EGCG plus ascorbic- and amino-acids (Epican forte) are ineffective in reduction of primary tumor growth and prevention of spontaneous liver metastases in this model.

CONCLUSIONS

Neither a formal clinical development nor the use of these substances can be recommended for neuroblastoma.

Liver metastasis models of colon cancer for evaluation of drug efficacy using NOD/Shi-scid IL2Rgammanull (NOG) mice

To examine the drug efficacy of a novel farnesyltransferase inhibitor (FTI), CH4512600, in vivo, we developed a reliable liver metastasis model of human colon cancer using NOD/Shi-scid IL2Rgamma(null) (NOG) mice. Eleven human colon cancer cell lines were examined for their ability to form diverse metastatic foci in the livers of NOG mice. When inoculated with 10(4) COLO320DM, HCT 116, HT-29, WiDr, LoVo and LS174T cells, liver metastasis was evident in 100% (6/6), 100% (6/6), 88.9% (8/9), 87.5% (7/8), 83.3% (5/6) and 50.0% (3/6) of the NOG mice, respectively. CaCo2, COLO201, LS123, SW48 and SW1417 showed no metastasis when seeded at 10(4) cells even in NOG mice. The mRNA expression levels and genetic mutations of N, H and K-RAS genes, which directly affect the levels of cellular RAS protein that would be molecular target for FTI, were also examined in these six metastatic human colon cancer cell lines for molecular biological and genotypic characteristics. Only three cell lines had a point mutation in the RAS oncogene. LS174T cell line had a point mutation of the K-RAS gene at codon 12 (gly12 --> asp; G12D), and HCT 116 and LoVo cell lines had a point mutation of the K-RAS gene at codon 13 (gly13 --> asp; G13D). Relative gene expression levels of N, H and K-RAS genes in the HCT 116 cell line were 2.6-5.0-fold lower than that of LS174T and LoVo cell lines. We selected HCT 116 cell line from our liver metastasis model for evaluation of FTI CH4512600 efficacy in vivo. Using the NOG mouse liver metastasis model, we demonstrated the effectiveness of FTI CH4512600 to suppress tumor growth in vivo and to prolong mouse survival significantly from 36.9+/-2.9 to 50.3+/-9.4 days.

Neuroendocrine differentiation in the 12T-10 transgenic prostate mouse model mimics endocrine differentiation of pancreatic beta cells

BACKGROUND

Neuroendocrine (NE) prostate cancer develops as an aggressive disease that does not respond to androgen ablation therapy. It has been demonstrated that the paracrine action of NE cells facilitates the progression of androgen dependent adenocarcinoma to an androgen independent state, suggesting a significant role for NE cells during failure of androgen ablation therapy.

METHODS

To investigate the pathways that are involved in NE differentiation of prostate cancer, we have looked at the expression of genes known to be involved in endocrine differentiation of beta-cells in the pancreas. This study has been performed using the NE prostate cancer mouse model (12T-10) and the derivative allograft model (NE-10).

RESULTS

Immunohistochemical studies have shown that the neuroendocrine prostate tumors express the transcription factors Foxa2, mouse achaete-scute homolog-1 (mash-1), neurogenin3 (Ngn3) and Nkx2.2. These tumors show a loss of hairy/enhancer of split (Hes-1), a gene that inhibits NE differentiation. Human NE prostate cancers also express Foxa2 and human achaete-scute homolog-1 (HASH-1). These genes are expressed in NE prostate tumors in the similar sequential manner as they appear in a pancreatic beta-cell endocrine differentiation. Foxa2 expression is detected in early prostatic intraepithelial neoplasia (PIN). Mash-1 expression is detected in a few clusters within low grade PIN lesions and Nkx2.2 expression is rarely detected in individual scattered cells within the PIN lesion. Ngn3 and Nkx2.2 frequently appear in the invasive NE cancer. Subsequent NE metastasis to lung and liver show a distinct gene expression pattern. The lung metastasis expresses Ngn3 but does not express Nkx2.2 whereas liver metastases do not express Ngn3 but express Nkx2.2.

CONCLUSIONS

These results suggest that Ngn3 and Nkx2.2 expression are markers for site-specific metastasis and/or transcriptionally regulated genes that are required for organ-specific metastasis. This study indicates that a pathway similar to pancreatic beta-cell differentiation is involved in NE differentiation of prostate cancer.

Tumor-selective gene expression in a hepatic metastasis model after locoregional delivery of a replication-competent retrovirus vector

PURPOSE

Replication-competent retrovirus (RCR) vectors have been shown to achieve highly efficient and tumor-restricted replicative spread and gene transfer in vivo after direct intratumoral injection in a variety of primary cancer models. In this setting, the intrinsic inability of retroviruses to infect postmitotic normal cells, combined with their unique ability to persist through stable integration, allow further transduction of ectopic tumor foci as the infected cancer cells migrate. However, i.v. delivery of RCR vectors has never been tested previously, particularly in an immunocompetent tumor model.

EXPERIMENTAL DESIGN

We combined optical imaging, flow cytometry, and molecular analysis to monitor RCR vector spread after administration via locoregional infusion in a hepatic metastasis model of colorectal cancer.

RESULTS

Robust RCR replication was first confirmed in both human WiDr and murine CT26 colorectal cancer cells in vitro, with transduction levels reaching >90% in <12 days after virus inoculation at multiplicities of infection of 0.01 to 0.1. In vivo, infusion of RCR supernatant into the portal circulation resulted in progressive and significant transduction of multifocal intrahepatic CT26 tumors in syngeneic mice, averaging about 30% but with up to 60% transduction in some tumors within 4 weeks. However, immunohistochemistry and quantitative PCR analysis showed no evidence of RCR spread to adjacent normal liver or to any other normal tissues.

CONCLUSIONS

Our results thus show that locoregional infusion of RCR vectors can be used to deliver therapeutic genes selectively to tumor cells in the liver while sparing normal hepatocytes and without dissemination to extrahepatic normal tissues.

[Treatment of mouse liver metastasis by intraportal injection of Adv-p53]

OBJECTIVE

To investigate the anti-tumor effect of intraportal administration of Adv-p53 in the treatment of the liver metastasis in mice.

METHODS

2 x 10(5) of MCA-205 cells were injected into the mouse portal vein to establish a murine liver metastasis model. The spleen was transpositioned subcutaneously to enable the administration of Adv-p53 continually into the portal system. Different doses of Adv-p53 were injected intraportally, while HBSS and Adv-CMV were injected intraportaly in the control group. Tumors in the liver were examined on day 21 after Adv-p53 administration.

RESULTS

The liver weight in the Adv-p53 treated mice on day 0 group (1.20 +/- 0.34 g) was significantly less than that in the Adv-CMV group (2.59 +/- 0.48 g, P < 0.05). The number of metastatic nodules in the Adv-p53 treated mice on day 0 group (9.0 +/- 9.9) was significantly less than that in the Adv-CMV group (57.1 +/- 11.3, P < 0.05), indicating that intraportal administration of Adv-p53 inhibited the formation of liver metastasis. This anti-tumor effect was in a dose-dependent manner. After the liver metastasis was formed, Adv-p53 was administered intraportally. The liver weight in the Adv-p53 treated mice on day 5 group (1.22 +/- 0.09 g) was significantly less than that in the Adv-CMV group (3.98 +/- 1.01 g , P < 0.05). The number of metastatic nodules in the Adv-p53 treaed mice on day 5 group (5.5 +/- 3.5) was significantly less than that in the Adv-CMV group (113.2 +/- 5.8, P < 0.05). Repeatedly intraportal administration of Adv-p53 could enhance this anti-tumor effect.

CONCLUSION

Local administration of Adv-p53 into the portal system would be a useful strategy for the liver metastasis treatment.

Reversion of immune tolerance in advanced malignancy: modulation of myeloid-derived suppressor cell development by blockade of stem-cell factor function

Tumor growth induced a significant increase of myeloid-derived suppressor cells (MDSCs) in the tumor-bearing host. In our previous study, we showed that MDSCs induced tumor-specific T-cell tolerance and the development of T regulatory cells (Tregs). Tumor-derived factors have been implicated in the accumulation of MDSCs. We hypothesize that reduction of MDSC accumulation in tumor-bearing hosts, through the blockade of tumor factors, can prevent T-cell anergy and Treg development and thereby improve immune therapy for the treatment of advanced tumors. Several tumor-derived factors were identified by gene array analysis. Among the candidate factors, stem- cell factor (SCF) is expressed by various human and murine carcinomas and was selected for further study. Mice bearing tumor cells with SCF siRNA knockdown exhibited significantly reduced MDSC expansion and restored proliferative responses of tumor-infiltrating T cells. More importantly, blockade of SCF receptor (ckit)-SCF interaction by anti-ckit prevented tumor-specific T-cell anergy, Treg development, and tumor angiogenesis. Furthermore, the prevention of MDSC accumulation in conjunction with immune activation therapy showed synergistic therapeutic effect when treating mice bearing large tumors. This information supports the notion that modulation of MDSC development may be required to achieve effective immune-enhancing therapy for the treatment of advanced tumors.

Therapeutic efficacy of replication-competent retrovirus vector-mediated suicide gene therapy in a multifocal colorectal cancer metastasis model

Replication-competent retrovirus (RCR) vectors are intrinsically incapable of infecting quiescent cells and have been shown to achieve highly efficient and tumor-restricted replicative spread and gene transfer in vivo after direct intratumoral injection in a variety of primary cancer models. However, i.v. delivery of RCR vectors expressing therapeutic genes has never previously been tested, particularly in an immunocompetent tumor model. Therefore, in the present study, we sought to test the therapeutic effect of an RCR vector (ACE-CD) carrying the yeast cytosine deaminase (CD) gene, which converts the nontoxic prodrug 5-fluorocytosine (5FC) into the chemotoxin 5-fluorouracil, after delivery by infusion into the locoregional circulation in a multifocal hepatic metastasis model of colon cancer. After confirmation of suicide gene cytotoxicity in vitro, multifocal hepatic tumors were established in syngeneic mice with murine CT26 colorectal cancer cells expressing firefly luciferase (CT26-Luc), and the ACE-CD vector was infused via intrasplenic injection into the portal circulation. Fourteen days after locoregional infusion, systemic administration of 5FC resulted in significant inhibition of bioluminescent signals in mice whose tumors had been infected with RCR but not in control mice. Notably, there was no detectable RCR vector spread to normal liver or bone marrow by quantitative PCR analysis. Our results thus show that locoregional delivery of a suicide gene by RCR vectors infused into the portal circulation results in progressive transduction of multiple tumor foci in the liver, without evidence of spread to adjacent normal parenchyma or extrahepatic tissues, and can achieve significant tumor growth inhibition.

Targeting of insulin-like growth factor-I receptor with a monoclonal antibody inhibits growth of hepatic metastases from human colon carcinoma in mice

BACKGROUND

Colorectal carcinomas (CRC) express high levels of insulin-like growth factor-I/II (IGF-I/II) and the receptor (IGF-IR). We hypothesized that selective inhibition of IGF-IR would inhibit hepatic growth of human CRC in mice.

METHODS

Human CRC cells were treated in vitro with anti-IGF-IR monoclonal antibody (MoAB) with and without oxaliplatin to assess cytotoxicity. The effect of anti-IGF-IR MoAB on IGF-I-induced vascular endothelial growth factor (VEGF) production in human CRC cells was assessed by Northern blot and ELISA. We injected human CRC cells intrahepatically in nude mice, and then administered anti-IGF-IR MoAB with and without oxaliplatin. We delayed treatment in one group until large hepatic tumors were present. We assessed tumors for apoptosis, proliferation, and angiogenesis.

RESULTS

Anti-IGF-IR MoAB and oxaliplatin inhibited CRC cell growth in vitro and combination treatment was even more effective. IGF-I stimulation of CRC cells resulted in significant upregulation of VEGF and this was completely inhibited by pretreatment with anti-IGF-IR MoAB. Anti-IGF-IR MoAB significantly inhibited hepatic growth of tumors in mice. Anti-IGF-IR MoAB plus oxaliplatin led to a significantly greater inhibition of tumor growth. Anti-IGF-IR MoAB plus oxaliplatin was just as effective at inhibiting growth of larger, more advanced liver tumors. Anti-IGF-IR MoAB, alone and in combination with oxaliplatin, led to a significant increase in tumor cell apoptosis, and a significant inhibition of tumor cell proliferation and angiogenesis.

CONCLUSIONS

These findings suggest that IGF-IR is a potential target for therapy in patients with advanced CRC.

The role of angiogenesis in endocrine liver metastases: an experimental study

Liver metastases are a major adverse event during the evolution of digestive endocrine tumors. However, little is known about their natural history and the determinants of their growth. In particular, whereas liver endocrine metastases, like their primary counterparts, are hypervascular, the role of tumor-associated angiogenesis has been little explored. We therefore designed an experimental model to study the intrahepatic growth of tumor endocrine cells; murine enteroendocrine STC-1 cells were injected into the spleen of nude mice to obtain their hepatic dissemination through the portal vein. Three stages of intrahepatic tumor growth were identified. Engraftment stage, until day 4 after intrasplenic injection of STC-1 cells, was avascular. Early growth, until day 17, resulted in small, infralobular nodules. Late growth, after day 17, was characterized by the development of large nodules associated with peritumoral vessels and containing abnormal intratumoral vessels. To test the effects of potentially anti-angiogenic agents on tumor growth, we then used STC-1 cells stably transfected with the endostatin-coding sequence. Intrahepatic tumor volume showed no significant change at days 4 and 8, but a dramatic decrease at day 28 (9.7 +/- 1.7% of liver tissue versus 25.2 +/- 2.4% in controls), because of a markedly lower number of large nodules (11 +/- 1.8% versus 42 +/- 5.8%) likely to result from an increased apoptotic index (39.4 +/- 5.6% versus 18.3 +/- 3.4). Our results suggest that active angiogenesis is not necessary for the engraftment and early growth of endocrine cells metastatic to the liver but is required at a later stage of progression.

Effect of vascular targeting agent Oxi4503 on tumor cell kinetics in a mouse model of colorectal liver metastasis

BACKGROUND

Oxi4503 has been shown to inhibit tumor growth and improve survival in an animal model of colorectal (CRC) liver metastases. This agent appears to selectively target the endothelial cytoskeleton with resultant vessel occlusion and tumor necrosis.

MATERIALS AND METHODS

This study evaluated the pattern of tumor necrosis caused by Oxi4503, with particular emphasis on patterns of cell proliferation and apoptosis in a murine model of CRC liver metastases.

RESULTS

A single dose of Oxi4503 caused immediate tumor vasculature collapse and subsequently tumor necrosis. There was widespread central necrosis with evidence of viable tumor cells at the periphery. Alterations in the number and spatial pattern of tumor cells undergoing apoptosis and the rate of cellular proliferation were also observed following treatment. Microvessel density was reduced following treatment, however patent vessels were still observed within the necrotic core.

CONCLUSION

Although Oxi4503 caused significant tumor destruction, synergistic treatment with cytotoxic and/or anti-angiogenic agents should be considered in order to achieve complete tumor eradication and long-term survival.

Cellular and molecular events associated with the antitumor response induced by the cytosine deaminase/5-fluorocytosine suicide gene therapy system in a rat liver metastasis model

The bacterial cytosine deaminase (CD) gene converts the non-toxic prodrug 5-fluorocytosine (5-FC) into 5-fluorouracil. We have previously shown, in a rat liver metastasis model from colon carcinoma, that intratumoral injection of a CD-expressing plasmid into the animals followed by 5-FC treatment results in the regression of the treated tumor as well as distant uninjected tumors. The aim of this study was to further analyze the mechanisms associated with tumor regression induced upon application of suicide CD/5-FC strategy. Tumor regression was associated with an increased apoptosis, the recruitment of natural killer cells, CD4- and CD8 T lymphocytes within the tumors and an increased expression of several cytokines/chemokines mRNAs. These data indicate that the CD/5-FC suicide strategy is associated with the triggering of cellular and molecular events leading to an efficient antitumor immune response involving both innate and acquired immunity.