Anticancer Effects of Sublingual Type I IFN in Combination with Chemotherapy in Implantable and Spontaneous Tumor Models

Salivary gland tumors are a heterogeneous group of neoplasms representing less than 10% of all head and neck tumors. Among salivary gland tumors, salivary duct carcinoma (SDC) is a rare, but highly aggressive malignant tumor resembling ductal breast carcinoma. Sublingual treatments are promising for SDC due to the induction of both local and systemic biological effects and to reduced systemic toxicity compared to other administration routes. In the present study, we first established that the sublingual administration of type I IFN (IFN-I) is safe and feasible, and exerts antitumor effects both as monotherapy and in combination with chemotherapy in transplantable tumor models, i.e., B16-OVA melanoma and EG.7-OVA lymphoma. Subsequently, we proved that sublingual IFN-I in combination with cyclophosphamide (CTX) induces a long-lasting reduction of tumor mass in NeuT transgenic mice that spontaneously develop SDC. Most importantly, tumor shrinkage in NeuT transgenic micewas accompanied by the emergence of tumor-specific cellular immune responses both in the blood and in the tumor tissue. Altogether, these results provide evidence that sublingual IFN holds promise in combination with chemotherapy for the treatment of cancer.

Humanization of Tumor Stroma by Tissue Engineering as a Tool to Improve Squamous Cell Carcinoma Xenograft

The role of stroma is fundamental in the development and behavior of epithelial tumors. In this regard, limited growth of squamous cell carcinomas (SCC) or cell-lines derived from them has been achieved in immunodeficient mice. Moreover, lack of faithful recapitulation of the original human neoplasia complexity is often observed in xenografted tumors. Here, we used tissue engineering techniques to recreate a humanized tumor stroma for SCCs grafted in host mice, by combining CAF (cancer associated fibroblasts)-like cells with a biocompatible scaffold. The stroma was either co-injected with epithelial cell lines derived from aggressive SCC or implanted 15 days before the injection of the tumoral cells, to allow its vascularization and maturation. None of the mice injected with the cell lines without stroma were able to develop a SCC. In contrast, tumors were able to grow when SCC cells were injected into previously established humanized stroma. Histologically, all of the regenerated tumors were moderately differentiated SCC with a well-developed stroma, resembling that found in the original human neoplasm. Persistence of human stromal cells was also confirmed by immunohistochemistry. In summary, we provide a proof of concept that humanized tumor stroma, generated by tissue engineering, can facilitate the development of epithelial tumors in immunodeficient mice.

Establishing a cryopreservation protocol for patient-derived xenografts of prostate cancer

BACKGROUND

Serially transplantable patient-derived xenografts (PDXs) are invaluable preclinical models for studying tumor biology and evaluating therapeutic agents. As these models are challenging to establish from prostate cancer specimens, the ability to preserve them through cryopreservation has several advantages for ongoing research. Despite this, there is still uncertainty about the ability to cryopreserve PDXs of prostate cancer. This study compared three different cryopreservation protocols to identify a method that can be used to reproducibly cryopreserve a diverse cohort of prostate cancer PDX models.

METHODS

One serially transplantable prostate cancer PDX from the Melbourne Urological Research Alliance cohort was used to compare three cryopreservation protocols: slow freezing in fetal calf serum (FCS) with 10% dimethyl sulfoxide (DMSO), FCS with 10% DMSO supplemented with the Rho-associated kinase (ROCK) inhibitor Y-27632 and vitrification. The efficiency of the slow freezing protocols was then assessed in 17 additional prostate cancer PDXs. Following cryopreservation, PDXs were re-established in host mice that were either intact and supplemented with testosterone or castrated. Graft take rate, tumor growth, histological features, and transcriptome profiles before and after cryopreservation were compared.

RESULTS

Slow freezing maintained the viability and histological features of prostate cancer PDXs, and the addition of a ROCK inhibitor increased their growth following cryopreservation. Using the slow freezing method, we re-established 100% of PDXs grown in either testosterone-supplemented or castrated host mice. Importantly, the long-term tumor growth rate and transcriptome profile were maintained following cryopreservation.

CONCLUSION

This study has identified a protocol to reliably cryopreserve and re-establish a diverse cohort of serially transplantable PDXs of prostate cancer. This study has the potential to significantly improve the practicality of maintaining PDX models. Cryopreservation may also increase the accessibility of these important resources and provide new opportunities for preclinical studies on a broader spectrum of prostate tumors.

How cancer cells attach to urinary bladder epithelium in vivo: study of the early stages of tumorigenesis in an orthotopic mouse bladder tumor model

The majority of bladder cancers in humans are non-muscle-invasive cancers that recur frequently after standard treatment procedures. Mouse models are widely used to develop anti-tumor treatments. The purpose of our work was to establish an orthotopic mouse bladder tumor model and to explore early stages of implantation of cancerous MB49 cells in vivo using various labeling and microscopic techniques. To distinguish cancer cells from normal urothelial cells in mouse urinary bladders, we performed molecular characterization of MB49 cells before intravesical injection experiments. In this new approach we applied internalized metal nanoparticles to unequivocally discriminate cancer cells from normal cells. This method revealed that cancer cells attached to the urothelium or basal lamina within just 1 hour of intravesical injection, whereas small tumors and localized hyperplastic urothelial regions developed within two days. We found that cancer cells initially adhere to normal urothelial cells through filopodia and by focal contacts with basal lamina. This is the first in vivo characterization of intercellular contacts between cancerous and normal urothelial cells in the bladder. Our study yields new data about poorly known early events of tumorigenesis in vivo, which could be helpful for the translation into clinic.

Circular RNA-ZFR Inhibited Cell Proliferation and Promoted Apoptosis in Gastric Cancer by Sponging miR-130a/miR-107 and Modulating PTEN

PURPOSE

This study aimed to probe into the associations among circular RNA ZFR (circ-ZFR), miR-130a/miR-107, and PTEN, and to investigate the regulatory mechanism of circ-ZFR‒miR-130a/miR-107‒PTEN axis in gastric cancer (GC).

MATERIALS AND METHODS

GSE89143 microarray data used in the study were acquired from publicly available Gene Expression Omnibus database to identify differentially expressed circular RNAs inGC tissues. The expressions of circ-ZFR, miR-130a, miR-107, and PTEN were examined by real-time reverse transcription polymerase chain reaction, while PTEN protein expression was measured by western blot. The variation of GC cell proliferation and apoptosis was confirmed by cell counting kit-8 assay and flow cytometry analysis. The targeted relationships among circZFR, miR-130a/miR-107, and PTEN were predicted via bioinformatics analysis and demonstrated by dual-luciferase reporter assay and RNA immunoprecipitation assay. The impact of ZFR on gastric tumor was further verified in xenograft mice model experiment.

RESULTS

Circ-ZFR and PTEN were low-expressed whereas miR-107 and miR-130a were highexpressed in GC tissues and cells. There existed targeted relationships and interactions between miR-130a/miR-107 and ZFR/PTEN. Circ-ZFR inhibited GC cell propagation, cell cycle and promoted apoptosis by sponging miR-107/miR-130a, while miR-107/miR-130a promoted GC cell propagation and impeded apoptosis through targeting PTEN. Circ-ZFR inhibited cell proliferation and facilitated apoptosis in GC by sponging miR-130a/miR-107 and modulating PTEN. Circ-ZFR curbed GC tumor growth and affected p53 protein expression in vivo.

CONCLUSION

Circ-ZFR restrained GC cell proliferation, induced cell cycle arrest and promoted apoptosis by sponging miR-130a/miR-107 and regulating PTEN.

Increased Vascular Permeability in the Bone Marrow Microenvironment Contributes to Disease Progression and Drug Response in Acute Myeloid Leukemia

The biological and clinical behaviors of hematological malignancies can be influenced by the active crosstalk with an altered bone marrow (BM) microenvironment. In the present study, we provide a detailed picture of the BM vasculature in acute myeloid leukemia using intravital two-photon microscopy. We found several abnormalities in the vascular architecture and function in patient-derived xenografts (PDX), such as vascular leakiness and increased hypoxia. Transcriptomic analysis in endothelial cells identified nitric oxide (NO) as major mediator of this phenotype in PDX and in patient-derived biopsies. Moreover, induction chemotherapy failing to restore normal vasculature was associated with a poor prognosis. Inhibition of NO production reduced vascular permeability, preserved normal hematopoietic stem cell function, and improved treatment response in PDX.

Neural Development by Transplanted Human Embryonal Carcinoma Stem Cells Expressing Green Fluorescent Protein

For many years, researchers have investigated the fate and potential of neuroectodermal cells during the development of the central nervous system. Although several key factors that regulate neural differentiation have been identified, much remains unknown about the molecular mechanisms that control the fate and specification of neural subtypes, especially in humans. Human embryonal carcinoma (EC) stem cells are valuable research tools for the study of neural development; however, existing in vitro experiments are limited to inducing the differentiation of EC cells into only a handful of cell types. In this study, we developed and characterized a novel EC cell line (termed TERA2.cl.SP12-GFP) that carries the reporter molecule, green fluorescent protein (GFP). We demonstrate that TERA2.cl.SP12-GFP stem cells and their differentiated neural derivatives constitutively express GFP in cells grown both in vitro and in vivo. Cellular differentiation does not appear to be affected by insertion of the transgene. We propose that TERA2.cl.SP12-GFP cells provide a valuable research tool to track the fate of cells subsequent to transplantation into alternative environments and that this approach may be particularly useful to investigate the differentiation of human neural tissues in response to local environmental signals.

Autologous reconstitution of human cancer and immune system in vivo

Correlative studies from checkpoint inhibitor trials have indicated that better understanding of human leukocytic trafficking into the human tumor microenvironment can expedite the translation of future immune-oncologic agents. In order to directly characterize signaling pathways that can regulate human leukocytic trafficking into the tumor, we have developed a completely autologous xenotransplantation method to reconstitute the human tumor immune microenvironment in vivo. We were able to genetically mark the engrafted CD34+ bone marrow cells as well as the tumor cells, and follow the endogenous leukocytic infiltration into the autologous tumor. To investigate human tumor intrinsic factors that can potentially regulate the immune cells in our system, we silenced STAT3 signaling in the tumor compartment. As expected, STAT3 signaling suppression in the tumor compartment in these autologously reconstituted humanized mice showed increased tumor infiltrating lymphocytes and reduction of arginase-1 in the stroma, which were associated with slower tumor growth rate. We also used this novel system to characterize human myeloid suppressor cells as well as to screen novel agents that can alter endogenous leukocytic infiltration into the tumor. Taken together, we present a valuable method to study individualized human tumor microenvironments in vivo without confounding allogeneic responses.

An original patient-derived xenograft of prostate cancer with cyst formation

BACKGROUND

The high rate of failure of new agents in oncology clinical trials indicates a weak understanding of the complexity of human cancer. Recent understanding of the mechanisms underlying castration resistance in prostate cancer led to the development of new agents targeting the androgen receptor pathway; however, their effectiveness is limited. Hence, there is a need for experimental systems that are able to better reproduce the biological diversity of prostate cancer in preclinical settings. In this study, we established a unique patient-derived xenograft (PDX) model to identify biomarkers for treatment efficacy and resistance and better understand prostate cancer biology.

METHODS

A prostate cancer tissue sample from a Japanese patient was transplanted subcutaneously into male, severe combined immune-deficient (SCID) mice and this PDX mouse model was named KUCaP3. Sequential tumor volume changes were observed before and after castration. Androgen receptor (AR), prostate-specific antigen (PSA), and other molecular markers were examined immunohistochemically. Sequence analysis of AR was also performed to detect mutations. Proteomic analysis of cyst fluid and sera samples of KUCaP3 mice were analyzed by mass spectrometry (MS).

RESULTS

KUCaP3 cell line, derived from human tissue, was successfully and serially passaged in vivo with approximately 60% take rate. KUCaP3 exhibited cyst formation, showed androgen-dependent growth initially, and developed castration-resistant growth several months after castration of the mice. Immunohistochemical analysis showed that KUCaP3 was positive for AR, PSA, CK18, and α-methyl acyl-coenzyme A racemase, but negative for CK5/6 and ERG. The AR gene in KUCaP3 cells contained a substitution from CAT (histidine) to TAT (tyrosine) at the nucleotide positions corresponding to codon 875 (H875Y) in the ligand-binding domain. Chemiluminescent immunoassay revealed higher levels of PSA in cystic fluid and the serum of KUCaP3-bearing mice. MS analysis detected 23 proteins of human origin in cystic fluids of KUCaP3.

CONCLUSIONS

We developed KUCaP3, an androgen-dependent PDX model with cyst formation. Several proteins including PSA were detected in the cystic fluid and sera of tumor-bearing mice. This original PDX model has the potential to be used as a clinically relevant model to evaluate molecular markers for prostate cancer diagnosis and treatment. Prostate 76:994-1003, 2016. © 2016 Wiley Periodicals, Inc.

[Solanine inhibits prostate cancer Du145 xenograft growth in nude mice by inducing cell cycle arrest in G1/S phase]

OBJECTIVE

To investigate the effect of solanine on the growth of human prostate cancer cell xenograft in nude mice.

METHODS

Human prostate cancer Du145 cells were injected into the subcutaneous layers on the back of nude mice. After a week, the mice bearing subcutaneous tumor graft were randomly divided into solanine treatment group and saline control group for treatment for 3 weeks. The tumor grafts were then harvested to evaluate the inhibition rate. The mRNA and protein expressions of cell cycle-related genes in the tumors were detected by qRT-PCR and Western blotting, respectively, and tumor cell apoptosis was detected using TUNEL method.

RESULTS

The tumor growth rate in solanine-treated group was significantly slower than that in the control group (P<0.01). The mRNA and protein expressions of C-myc, cyclin D1, cyclin E1, CDK2, CDK4 and CDK6 were significantly inhibited by solanine. Solanine significantly up-regulated p21 mRNA and protein expression in the tumors and induced a higher apoptosis rate of the tumor cells than saline (P<0.01).

CONCLUSION

The tumor-inhibition effect of solanine is probably mediated by regulating the expressions of genes related with G1/S cell cycle arrest and cell apoptosis.

Analysis of TMEFF2 allografts and transgenic mouse models reveals roles in prostate regeneration and cancer

BACKGROUND

Previous results from our lab indicate a tumor suppressor role for the transmembrane protein with epidermal growth factor and two follistatin motifs 2 (TMEFF2) in prostate cancer (PCa). Here, we further characterize this role and uncover new functions for TMEFF2 in cancer and adult prostate regeneration.

METHODS

The role of TMEFF2 was examined in PCa cells using Matrigel(TM) cultures and allograft models of PCa cells. In addition, we developed a transgenic mouse model that expresses TMEFF2 from a prostate specific promoter. Anatomical, histological, and metabolic characterizations of the transgenic mouse prostate were conducted. The effect of TMEFF2 in prostate regeneration was studied by analyzing branching morphogenesis in the TMEFF2-expressing mouse lobes and alterations in branching morphogenesis were correlated with the metabolomic profiles of the mouse lobes. The role of TMEFF2 in prostate tumorigenesis in whole animals was investigated by crossing the TMEFF2 transgenic mice with the TRAMP mouse model of PCa and analyzing the histopathological changes in the progeny.

RESULTS

Ectopic expression of TMEFF2 impairs growth of PCa cells in Matrigel or allograft models. Surprisingly, while TMEFF2 expression in the TRAMP mouse did not have a significant effect on the glandular prostate epithelial lesions, the double TRAMP/TMEFF2 transgenic mice displayed an increased incidence of neuroendocrine type tumors. In addition, TMEFF2 promoted increased branching specifically in the dorsal lobe of the prostate suggesting a potential role in developmental processes. These results correlated with data indicating an alteration in the metabolic profile of the dorsal lobe of the transgenic TMEFF2 mice.

CONCLUSIONS

Collectively, our results confirm the tumor suppressor role of TMEFF2 and suggest that ectopic expression of TMEFF2 in mouse prostate leads to additional lobe-specific effects in prostate regeneration and tumorigenesis. This points to a complex and multifunctional role for TMEFF2 during PCa progression.

Real-time Non-invasive Spectral Imaging of Orthotopic Red Fluorescent Protein-expressing Lung Tumor Growth in Nude Mice

BACKGROUND/AIM

Orthotopic implantation of cancer allows metastasis to occur. The most patient-like metastatic orthotopic models are developed with surgical orthotopic implantation using intact tissue in order to preserve the natural tissue structure of the tumor which contains both cancer cells and stroma.

MATERIALS AND METHODS

In the present study, we performed a simple thoracotomy by making an intercostal incision between the fourth and fifth ribs on the left side of the chest of nude mice. Lung tumor fragments expressing red fluorescent protein were then implanted on the left lung.

RESULTS

It was possible to monitor tumor formation in the lung non-invasively by spectral imaging using the Maestro system with a liquid tunable filter. The model described here has high tumorigenicity in the lung (100%) and a low mortality rate (5%).

CONCLUSION

This imageable nude mouse model using surgical orthotopic implantation of lung cancer will be useful for all types of longitudinal studies.

NOD/SCID-GAMMA mice are an ideal strain to assess the efficacy of therapeutic agents used in the treatment of myeloma bone disease

Animal models of multiple myeloma vary in terms of consistency of onset, degree of tumour burden and degree of myeloma bone disease. Here we describe five pre-clinical models of myeloma in NOD/SCID-GAMMA mice to specifically study the effects of therapeutic agents on myeloma bone disease. Groups of 7–8 week old female irradiated NOD/SCID-GAMMA mice were injected intravenously via the tail vein with either 1x10⁶ JJN3, U266, XG-1 or OPM-2 human myeloma cell lines or patient-derived myeloma cells. At the first signs of morbidity in each tumour group all animals were sacrificed. Tumour load was measured by histological analysis, and bone disease was assessed by micro-CT and standard histomorphometric methods. Mice injected with JJN3, U266 or OPM-2 cells showed high tumour bone marrow infiltration of the long bones with low variability, resulting in osteolytic lesions. In contrast, mice injected with XG-1 or patient-derived myeloma cells showed lower tumour bone marrow infiltration and less bone disease with high variability. Injection of JJN3 cells into NOD/SCID-GAMMA mice resulted in an aggressive, short-term model of myeloma with mice exhibiting signs of morbidity 3 weeks later. Treating these mice with zoledronic acid at the time of tumour cell injection or once tumour was established prevented JJN3-induced bone disease but did not reduce tumour burden, whereas, carfilzomib treatment given once tumour was established significantly reduced tumour burden. Injection of U266, XG-1, OPM-2 and patient-derived myeloma cells resulted in less aggressive longer-term models of myeloma with mice exhibiting signs of morbidity 8 weeks later. Treating U266-induced disease with zoledronic acid prevented the formation of osteolytic lesions and trabecular bone loss as well as reducing tumour burden whereas, carfilzomib treatment only reduced tumour burden. In summary, JJN3, U266 or OPM-2 cells injected into NOD/SCID-GAMMA mice provide robust models to study anti-myeloma therapies, particularly those targeting myeloma bone disease.

In vitro culture and characterization of human lung cancer circulating tumor cells isolated by size exclusion from an orthotopic nude-mouse model expressing fluorescent protein

In the present study, we demonstrate an animal model and recently introduced size-based exclusion method for circulating tumor cells (CTCs) isolation. The methodology enables subsequent in vitro CTC-culture and characterization. Human lung cancer cell line H460, expressing red fluorescent protein (H460-RFP), was orthotopically implanted in nude mice. CTCs were isolated by a size-based filtration method and successfully cultured in vitro on the separating membrane (MetaCell®), analyzed by means of time-lapse imaging. The cultured CTCs were heterogeneous in size and morphology even though they originated from a single tumor. The outer CTC-membranes were blebbing in general. Abnormal mitosis resulting in three daughter cells was frequently observed. The expression of RFP ensured that the CTCs originated from lung tumor. These readily isolatable, identifiable and cultivable CTCs can be used to characterize individual patient cancers and for screening of more effective treatment.

Introduction of 65 kDa Antigen ofMycobacterium tuberculosisto Cancer Cells Enhances Anti-Tumor Effect of BCG Therapy

Bacillus Calmette Guerin (BCG) immunotherapy has anti-tumorigenic effects against bladder cancer. To improve the efficacy of BCG therapy, we introduced the gene encoding the 65 kDa heat shock protein (hsp) of Mycobacterium tuberculosis into a mouse malignant melanoma cell line (B16). An expression vector harboring the 65 kDa antigen gene was transfected into B16 using Lipofectamine, then expression of the antigen was confirmed by RT-PCR and Western blotting. Several cell lines expressing 65 kDa antigen were established (B16/65 kDa). We also established a control cell line transfected with the vector alone (B16/con). All cell lines (B16, B16/con, B16/65 kDa) were injected intraperitoneally into syngeneic mice with or without BCG prior immunization and the development of tumor ascites was examined. To analyze the mechanism of the anti-tumor effect, CD4 T cells or CD8 T cells were depleted in vivo by administering the corresponding monoclonal antibody. B16/65k Da expressed the 65 kDa hsp of M. tuberculosis. The tumor growth of B16/65 kDa was slightly retarded in naive mice, but significantly inhibited by BCG. The anti-tumor effect was totally abrogated in mice deficient in CD4 T cells, suggesting that CD4 T cells are involved in this process. The 65 kDa hsp of M. tuberculosis was expressed after gene transduction in a malignant melanoma cell line and significantly enhanced the anti-tumor effect of BCG immunotherapy. CD4 T cells play an important role in this anti-tumor effect.

The utility of fecal corticosterone metabolites and animal welfare assessment protocols as predictive parameters of tumor development and animal welfare in a murine xenograft model

The aim of the present study was to evaluate the utility of various non-invasive parameters for the prediction of tumor development and animal welfare in a murine xenograft model in male C.B-17 SCID (C.B-Igh-1(b)/IcrTac-Prkdc(scid)) mice. The study showed that body weight, food and water consumption, and an animal welfare assessment (AWA) protocol revealed marked differences between control and cancer lines as the size of the tumor increased. However, only the AWA protocol was effective in predicting the tumor size and the level of fecal corticosterone metabolites (FCM). FCM levels were, however, negatively-correlated to the AWA score, and the tumor size, both when evaluated on a given day and when accumulated over the entire period. In conclusion, the present study demonstrated that body weight and food and water consumption were negatively-affected as tumor developed but only the animal welfare protocol could be used to predict tumor size.

Establishment and characterization of xenograft models of human neuroblastoma bone metastasis

OBJECTS

To improve the therapy of advanced neuroblastoma (NB), it is critical to develop animal models that mimic NB bone metastases. Unlike the human disease, NB xenograft models rarely metastasize spontaneously to bone from the orthotopic site of primary tumor growth.

METHODS

Single-cell suspensions of SY5Y, KCNR NB cells were injected directly into the femur of nude mice. Radiological and histological analyses and immunohistochemistry analyses were performed to characterize these osseous NB models. SY5Y and KCNR result in osteolytic responses.

RESULTS

We have detected osteoprotegerin, receptor activator of nuclear factor kappa B ligand, parathyroid hormone-related protein, and endothelin-1, proteins associated with bone growth and osteolysis, and C-X-C chemokine receptor type 4 (CXCR4) involved in tumor growth and tumor cell migration in the NB cells grown in the bone.

CONCLUSIONS

These animal models can be used to study biological interactions, pathways, and potential therapeutic targets and also to evaluate new agents for treatment and prevention of NB bone metastasis.

Obesity and intermittent hypoxia increase tumor growth in a mouse model of sleep apnea

BACKGROUND

Intermittent hypoxia and obesity which are two pathological conditions commonly found in patients with obstructive sleep apnea (OSA), potentially enhance cancer progression.

OBJECTIVE

To investigate whether obesity and/or intermittent hypoxia (IH) mimicking OSA affect tumor growth.

METHODS

A subcutaneous melanoma was induced in 40 mice [22 obese (40-45g) and 18 lean (20-25g)] by injecting 10(6) B16F10 cells in the flank. Nineteen mice (10 obese/9 lean) were subjected to IH (6h/day for 17days). A group of 21 mice (12 obese/9 lean) were kept under normoxia. At day 17, tumors were excised, weighed and processed to quantify necrosis and endothelial expression of vascular endothelial growth factor (VEGF) and CD-31. VEGF in plasma was also assessed.

RESULTS

In lean animals, IH enhanced tumor growth from 0.81±0.17 to 1.95±0.32g. In obese animals, a similar increase in tumor growth (1.94±0.18g) was observed under normoxia, while adding IH had no further effect (1.69±0.23g). IH only promoted an increase in tumoral necrosis in lean animals. However, obesity under normoxic conditions increased necrosis, VEGF and CD-31 expression in tumoral tissue. Plasma VEGF strongly correlated with tumor weight (ρ=0.76, p<0.001) in the whole sample; it increased in lean IH-treated animals from 66.40±3.47 to 108.37±9.48pg/mL, p<0.001), while the high baseline value in obese mice (106.90±4.32pg/mL) was unaffected by IH.

CONCLUSIONS

Obesity and IH increased tumor growth, but did not appear to exert any synergistic effects. Circulating VEGF appeared as a crucial mediator of tumor growth in both situations.

Intra-mammary ductal transplantation: a tool to study premalignant progression

Ductal carcinoma in situ (DCIS) is a non-obligate precursor to invasive breast cancer. Although there is extensive information on the cellular and molecular changes in DCIS, there is limited ability to functionally test. The critical changes in premalignant progression. This review summarizes our experience with a recently developed method which provides. The opportunity to functionally test the molecular events occuring to functionally test the molecular events occurring in the initial changes in premaligant progression; i.e., the step from non-invasive to invasive behavior.

A methodological approach to unravel organ-specific breast cancer metastasis

Breast cancer is the most commonly diagnosed and the second highest cause of cancer-related mortality. Although major breakthroughs have emerged during the past decades concerning the characterization of major malignant tumors hallmarks, little is known about the molecular process that sustains the most deadly feature of cancer: metastasis to distant organs. In fact, this colonization of tumor cells to secondary sites is not random but rather orientated, and depends on several signalling events that are not fully elucidated yet. Understanding the precise molecular and cellular mechanisms accountable for the specific invasion of tissues by breast cancer cells is likely to be important for developing new therapeutic strategies to effectively prevent metastasis in patients diagnosed with early cancer lesions. Here, we briefly describe a multidisciplinary approach based on the molecular profiling of breast cancer metastases, the elaboration of prognostic gene signatures, the clinical validation and the experimental confirmation using cell and animal models to better address breast cancer metastasis. This methodology can be considered as a useful workflow to identify and validate the genes that trigger and support organ tropism of breast cancer cells during metastasis.

If you don't look, you won't see: intravital multiphoton imaging of primary and metastatic breast cancer

A fundamental hallmark of cancer is progression to metastasis and the growth of breast cancer metastases in lung, bone, liver and/or brain causes fatal complications. Unfortunately, the cellular and biochemical mechanisms of the metastatic process remain ill-defined. Recent application of intravital multiphoton microscopy (MP-IVM) to image fluorescently labeled cells in mouse models of cancer has allowed dynamic observation of this multi-step process at the cellular and subcellular levels. In this article, we discuss the use of MP-IVM in studies of breast cancer metastasis, as well as surgical techniques for exposing tumors prior to imaging. We also describe a versatile multiphoton microscope for imaging tumor-stroma interactions.

CD99-dependent expansion of myeloid-derived suppressor cells and attenuation of graft-versus-host disease

CD99 is involved in many cellular events, such as the generation of Hodgkin and Reed-Sternberg cells, T cell costimulation, and leukocyte transendothelial migration. However, these studies have been limited to in vitro or in vivo experiments using CD99-deficient cell lines or anti-CD99 antibodies. In the present study, using CD99-deficient mice established by the exchangeable gene trap method, we investigated the physiologic function of murine CD99. In a B6 splenocytes → bm12 graft-versus-host disease model, wild-type cells were minimally lethal, whereas all mice that received CD99-deficient donor cells developed an early and more severe pathology. Graftversus-host disease in these mice was associated with insufficient expansion of myeloid-derived suppressor cells. This was confirmed by experiments illustrating that the injection of wild-type donor cells depleted of Mac-1(+) cells led to an almost identical disease course as the CD99-deficient donor system. Therefore, these results suggest that CD99 plays a crucial role in the attenuation of graft-versus-host disease by regulating the expansion of myeloid-derived suppressor cells.

Subclinical vitamin A deficiency does not increase development of tumors in irradiated or unirradiated lungs

Cancer patients often have subclinical vitamin A deficiencies and low vitamin A lung levels. Previous studies showed that subclinical vitamin A deficiency increased the severity of pneumonitis induced by whole-lung irradiation in rats. Many studies have shown that lung irradiation increases the number of lung tumors developing from intravenously injected tumor cells in mice. We examined the impact of vitamin A deficiency on the development of lung metastases from a highly metastatic syngeneic rat rhabdomyosarcoma in normal rats and rats receiving prior lung irradiation. Weanling female WAGrijY rats were randomized to receive either a diet lacking both vitamin A and beta-carotene or a control diet. After five weeks, the deficient diet significantly decreased levels of retinol in the lung and liver but not in the serum, modeling the tissue and blood levels seen in prior studies of patients with subclinical vitamin A inadequacy. The vitamin A-deficient diet did not alter the number of lung tumors developing from intravenously injected tumor cells in unirradiated rats. Whole-lung irradiation produced dose-dependent increases in the number of lung tumors developing from tumor cells injected intravenously one or 29 d after irradiation. Vitamin A deficiency did not alter these dose-response curves, indicating that the more intense radiation-induced pneumonitis seen previously in vitamin A-deficient rats did not alter the enhancement of metastases produced by whole-lung irradiation. Moreover, inadequate vitamin A intake did not influence the growth of tumors implanted subcutaneously or increase the number or size of the spontaneous lung metastases developing from these subcutaneous tumors. Thus, although low vitamin A status influences the development of lung injury and is considered a possible modifiable risk factor increasing risk of primary cancer, it did not affect the growth of subcutaneous tumors or increase the development of artificial or spontaneous lung metastases in this rat model.

Of mice and women: A short history of mouse mammary cancer research with an emphasis on the paradigms inspired by the transplantation method

The ability to transplant mammary epithelial cells of any age or developmental stage to the normal anatomical site of an inbred recipient mouse strain has revolutionized the studies of mammary development and tumor biology over the past 50 years. This simple method has made the mammary gland of the rodent one of the most accessible and studied organs and facilitated our understanding of the fundamental cellular and molecular properties of normal and neoplastic development. This short review outlines the early concepts that led to the development of the transplantation technology and the impact of this method on our understanding for a variety of processes important both for the normal development and differentiation of the gland as well as the phenomena of neoplastic progression.

Establishment of in vivo fluorescence imaging in mouse models of malignant mesothelioma

Malignant mesothelioma is a highly aggressive tumor with poor prognosis, and new treatment paradigms are urgently needed. For testing preclinical efficacy of new therapeutic agents, establishment of appropriate animal models is crucial. We developed in vivo fluorescence imaging models for human malignant mesothelioma in mice using tumor cells engineered to express fluorescent proteins (EGFP, mRFP, mCherry, and mPlum) by lentiviral vectors. Among these fluorescent proteins, the expression of mCherry protein in the transduced tumor cells was shown to be robust and stable both in vitro and in vivo. In both, peritoneally disseminated and orthotopic pleural mesothelioma models, mCherry-positive tumors were sensitively detected and tumor growth was successfully monitored. This represents the first study to achieve sensitive tumor detection and tracking of tumor growth and development in the malignant mesothelioma mouse models by non-invasive in vivo fluorescence imaging. These imaging models can be versatile and powerful tools to explore new treatment paradigms for malignant mesothelioma.

Serially heterotransplanted human prostate tumours as an experimental model

* Introduction * Serially heterotransplanted human tumours in immunosuppressed mice: similarity to the tumour of origin - Cytological and histological analysis - Karyotype - Marker expression - Other PC markers - Tumour cell proliferation and frequency of mitosis - Vasculature - Stromal compartment - Heterotransplant hormone dependency - Androgen dependent - Partially androgen dependent - Androgen independent - Metastases * Conclusions Preclinical research on prostate cancer (PC) therapies uses several models to represent the human disease accurately. A common model uses patient prostate tumour biopsies to develop a cell line by serially passaging and subsequent implantation, in immunodeficient mice. An alternative model is direct implantation of patient prostate tumour biopsies into immunodeficient mice, followed by serial passage in vivo. The purpose of this review is to compile data from the more than 30 years of human PC serial heterotransplantation research. Serially heterotransplanted tumours are characterized by evaluating the histopathology of the resulting heterotransplants, including cellular differentiation, karyotype, marker expression, hormone sensitivity, cellular proliferation, metastatic potential and stromal and vascular components. These data are compared with the initial patient tumour specimen and, depending on available information, the patient's clinical outcome was compared with the heterotransplanted tumour. The heterotansplant model is a more accurate preclinical model than older generation serially passaged or genetic models to investigate current and newly developed androgen-deprivation agents, antitumour compounds, anti-angiogenic drugs and positron emission tomography radiotracers, as well as new therapeutic regimens for the treatment of PC.

Anti-tumor effects of fusion vaccine prepared by renal cell carcinoma 786-O cell line and peripheral blood dendritic cells of healthy volunteers in vitro and in human immune reconstituted SCID mice

Dendritic cells (DC), as professional antigen presenting cells, play the central role in the process of body initiating the anti-tumor immunity, and the study on DC anti-tumor vaccine has become heated in recent years. In this study, we used polyethylene glycol (PEG) to induce renal cell carcinoma (RCC) 786-O cell line fused with peripheral blood DC of healthy volunteers, and discuss the biological characteristics of fusion vaccine and its anti-tumor effects in vitro and in human immune reconstituted SCID mice model of RCC. The study found that PEG could effectively induce cell fusion, and the expressions of CD86 and HLA-DR in fusion vaccine group were significantly up-regulated compared with the DC control group; the secretion of IL-12 was much higher and longer than that of the control; the functions of dendritic cell-tumor fusion vaccine to stimulate the proliferation of allogenic T lymphocytes and to kill RCC786-O cells in vitro were significantly higher than those of the control group, and after the killing, apoptosis body was observed in the target cells; after the injection of fusion vaccine into human immune reconstituted SCID mice model of RCC786-O via vena caudalis, the volume of mice tumor was reduced significantly, proliferation index of tumor cells decreased obviously compared with that of the control group, and more hemorrhage and putrescence focuses presented, accompanying large quantity of lymphocytes soakage. The results of this experimental study shows that fusion vaccine of RCC786-O cell line and DC can significantly stimulate the proliferation of allogenic T cells and specifically inhibit and kill RCC cells in vitro and in vivo, which makes the DC-RCC786-O fusion vaccine a possible new way of effective RCC immunotherapy.

New anti-CD30 human pancreatic ribonuclease-based immunotoxin reveals strong and specific cytotoxicityin vivo

Although the therapy of Hodgkin lymphoma and anaplastic large cell lymphoma has been considerably improved during the last decades, high therapeutic toxicity, relapses, secondary tumors, and primary treatment failure(s) occur. Both malignancies are well suited for CD30-targeted immunotherapy because of their strong CD30 expression. We constructed an immunotoxin composed of a single chain variable fragment of a CD30 antibody fused to the human pancreatic ribonuclease, showing CD30-specific binding and ribonucleolytic activity resistant to the inhibitor RNasin. This immunotoxin revealed CD30-specific anti-tumor activity in BALB/c mice that were challenged with CD30-positive or CD30-negative syngeneic tumor cells.

Tumor initiating cancer stem cells from human breast cancer cell lines

Breast cancer is composed of heterogeneous cell populations with different biological properties. The capacity to form tumors resides in a small group of cells termed tumor initiating cells or cancer stem cells. Tumor initiating cells have been identified in a variety of cancers by sorting of subpopulations based on cell surface markers and transplantation into animal models. Tumor initiating cells have the important feature of self renewal, which is a property in common with stem cells. We examined established breast cancer lines for cells with tumor initiating properties. A dye efflux side population in MCF7 and T47D lines expressed markers of breast cancer stem cells. The side population represents a distinct morphologic and functional subpopulation within the human breast cancer cell lines MCF7 and T47D. The side population from human breast cancer cell lines was able to initiate tumors in vivo. The side population cells from human breast cancer cell lines were more resistant to ionizing radiation than the non-side population. We concluded that tumor initiating cells exist in established human breast cancer cell lines.

[MRI monitoring of cerebral spinal fluid metastasis in rabbit model]

OBJECTIVE

To establish a rabbit model of cerebral spinal flow metastasis, to analyze the growth rate of tumor, and to investigate the value of MRI in monitoring the biology of tumor compared with pathology.

METHODS

Twenty-four New Zealand white rabbits were inoculated with suspension of VX(2) tumor cells in the subarachnoid space via the foramen magnum (experimental group), and 6 rabbits were inoculated with normal saline (control group). MRI examination, including non-enhanced T(1)WI, T(2)WI, and FLAIR sequences and then T(1)WI, FLAIR after dynamic contrast enhanced with Gd-DTPA were done 7 approximately 22 days after inoculation with a 3-day interval. The rabbits were killed after the last MRI scan with their spinal cords, spinal meninges, and tumor taken out to undergo microscopy.

RESULTS

(1) MRI plain scan showed that in the experimental group 2 nodi in the medulla and 1 nodes in the cervical spinal cord were found with low signal on T(1)WI and high signal on T(2)WI; and FLAIR imaging showed local lesions with medial signal in 6 rabbits (25%). And no abnormal signs were seen in the control group. (2) MRI enhancement showed that in the experimental group the images of 15 rabbit models were enhanced markedly with irregular thickening of meninges or nodules at the subarachnoid space on T(1)WI, positive signs were confirmed on FLAIR sequence in 16 of the 24 rabbits, and positive signs were noted on DCE-MRI scanning in 18 of the 24 rabbits (75%). In the control group 5 of the 6 rabbits were negative in images. Microscopy showed thickened of meninges and spinal meninges in 20 of the 24 rabbits of the experimental group and spinal cord metastasis in 22 rabbits. No pathological changes were seen in the control group. Statistics showed a CSF metastasis rate of 91.67%. There were significant difference between the plain scan and T(1)WI with enhancement (P < 0.01) and between FLAIR scan and FLAIR enhancement scans. There was a significant difference between T(1)WI and FLAIR enhancement and pathological findings (P < 0.05). There was no significant difference between DCE-MRI method and pathological results (P > 0.05).

CONCLUSION

Gd-DTPA enhanced MRI scan sequences has a high sensitivity and specificity and can be used in monitoring the growth of CSF metastasis. There is a disparity between the MRI signs and pathological findings. It is a key that to improve the spatial resolution of machine and to investigate the best method for detecting early metastasis.

Direct orthotopic transplantation of fresh surgical specimen preserves CD133+ tumor cells in clinically relevant mouse models of medulloblastoma and glioma

Recent identification of cancer stem cells in medulloblastoma (MB) and high-grade glioma has stimulated an urgent need for animal models that will not only replicate the biology of these tumors, but also preserve their cancer stem cell pool. We hypothesize that direct injection of fresh surgical specimen of MB and high-grade glioma tissues into anatomically equivalent locations in immune-deficient mouse brains will facilitate the formation of clinically accurate xenograft tumors by allowing brain tumor stem cells, together with their non-stem tumor and stromal cells, to grow in a microenvironment that is the closest to human brains. Eight of the 14 MBs (57.1%) and two of the three high-grade gliomas (66.7%) in this study developed transplantable (up to 12 passages) xenografts in mouse cerebellum and cerebrum, respectively. These xenografts are patient specific, replicating the histopathologic, immunophenotypic, invasive/metastatic, and major genetic (analyzed with 10K single nucleotide polymorphism array) abnormalities of the original tumors. The xenograft tumor cells have also been successfully cryopreserved for long-term preservation of tumorigenicity, ensuring a sustained supply of the animal models. More importantly, the CD133(+) tumor cells, ranging from 0.2%-10.4%, were preserved in all the xenograft models following repeated orthotopic subtransplantations in vivo. The isolated CD133(+) tumor cells formed neurospheres and displayed multi-lineage differentiation capabilities in vitro. In summary, our study demonstrates that direct orthotopic transplantation of fresh primary tumor cells is a powerful approach in developing novel clinical relevant animal models that can reliably preserve CD133(+) tumor cell pools even during serial in vivo subtransplantations. Disclosure of potential conflicts of interest is found at the end of this article.

A spontaneous estrogen dependent, tamoxifen sensitive mouse mammary tumor: a new model system to study hormone-responsiveness in immune competent mice

Currently, an in vivo spontaneous model of estrogen dependent, tamoxifen sensitive breast cancer does not exist. We show here the characterization of the M05 mammary tumor that appeared spontaneously in a 1-year-old virgin female BALB/c mouse in our animal facility. The M05 tumor is a semi-differentiated adenocarcinoma that expresses estrogen and progesterone receptors. When it was transplanted to either male or ovariectomized female mice it did not grow. Moreover, ovariectomy or treatment with tamoxifen of tumor bearing mice led to a halt in tumor growth. Treatment of ovariectomized mice that had been inoculated with the M05 tumor showed that only estradiol, but not progesterone, promoted the re-growth of the tumor. Finally, after passage nine, tumor growth was achieved in male and ovariectomized female mice suggesting that the tumor had progressed to hormone independence. However, like often found in the clinic, expression of estrogen and progesterone receptors was maintained. This model mimics the biology of estrogen receptor positive breast cancer in humans and presents itself as an invaluable tool for the study of endocrine resistance in a physiologically relevant setting.

[Correlated changes and value of redox-status, nitric oxide and blood supply in experimental malignant tumor growth]

With the use of methods of electronic paramagnetic resonance (EPR) and polarography EPR specter of tumor tissue, content of free nitric oxide and intensity of local hemo circulation in dynamics of sarcoma S-45 growth has been studied. It was stated that the intensity of local hemo circulation (especially in center of tumor tissue) progressively decreases. Sharp decrease of hemo circulation in the central part of the tumor tissue could be explained by drastically reduced concentration of NO, which in turn is related to disorders in electron transport in mitochondrial respiratory chain and probably to conversion of NO into toxic peroxinitrite. The relatively less expressed decrease of local hemo circulation in periphery, despite impaired reheological features of the blood, is explained by increased concentration of NO. It is suggest, that tumor tissue blood supply enhancement increases chemotherapeutic effects via affecting energetic metabolism in mitochondria, redox-status and concentration of free NO.

Side population cells isolated from mesenchymal neoplasms have tumor initiating potential

Although many cancers are maintained by tumor-initiating cells, this has not been shown for mesenchymal tumors, in part due to the lack of unique surface markers that identify mesenchymal progenitors. An alternative technique to isolate stem-like cells is to isolate side population (SP) cells based on efflux of Hoechst 33342 dye. We examined 29 mesenchymal tumors ranging from benign to high-grade sarcomas and identified SP cells in all but six samples. There was a positive correlation between the percentage of SP cells and the grade of the tumor. SP cells preferentially formed tumors when grafted into immunodeficient mice, and only cells from tumors that developed from the SP cells had the ability to initiate tumor formation upon serial transplantation. Although SP cells are able to efflux rhodamine dye in addition to Hoechst 33342, we found that the ability to efflux rhodamine dye did not identify a population of cells enriched for tumor-initiating capacity. Here, we identify a subpopulation of cells within a broad range of benign and malignant mesenchymal tumors with tumor-initiating capacity. In addition, our data suggest that the proportion of SP cells could be used as a prognostic factor and that therapeutically targeting this subpopulation of cells could be used to improve patient outcome.

Real-time imaging of tumor-cell shedding and trafficking in lymphatic channels

In the present report, we show real-time imaging of cancer cell trafficking in lymphatic vessels. Cancer cells labeled with both green fluorescent protein (GFP) in the nucleus and red fluorescent protein (RFP) in the cytoplasm or with GFP only or RFP only were injected into the inguinal lymph node of nude mice. The labeled cancer cells trafficked through lymphatic vessels where they were imaged via a skin flap in real time at the cellular level until they entered the axillary lymph node. The bright fluorescence of the cancer cells and the real-time microscopic imaging capability of the Olympus OV100 small-animal imaging system enabled imaging of the trafficking cancer cells in the lymphatics. Using this imaging strategy, two different cancer cell lines, one expressing GFP and the other expressing RFP, were simultaneously injected in the inguinal lymph node. Fluorescence imaging readily distinguished the two color-coded cell lines and their different abilities to survive in the lymphatic system. Using this imaging technology, we also investigated the role of pressure on tumor-cell shedding into lymphatic vessels. Pressure was generated by placing 25- and 250-g weights for 10 s on the bottom surface of a tumor-bearing footpad. Tumor cell fragments, single cells, and emboli shed from the footpad tumor were easily distinguished with the labeled cells and OV100 imaging system. Increasing pressure on the tumor increased the numbers of shed cells, fragments, and emboli. Pressure also deformed the shed emboli, increasing their maximum major axis. Imaging lymphatic trafficking of cancer cells can reveal critical steps of lymph node metastasis.

Cytokine-dependent imatinib resistance in mouse BCR-ABL+, Arf-null lymphoblastic leukemia

Retroviral transduction of the BCR-ABL kinase into primary mouse bone marrow cells lacking the Arf tumor suppressor rapidly generates polyclonal populations of continuously self-renewing pre-B cells, virtually all of which have leukemic potential. Intravenous infusion of 20 such cells into healthy syngeneic mice induces rapidly fatal, transplantable lymphoblastic leukemias that resist imatinib therapy. Introduction of BCR-ABL into Arf-null severe combined immunodeficient (SCID) bone marrow progenitors lacking the cytokine receptor common gamma-chain yields leukemogenic pre-B cells that exhibit greater sensitivity to imatinib in vivo. Hence, salutary cytokines in the hematopoietic microenvironment can facilitate leukemic proliferation and confer resistance to targeted therapy.

Inhibition of GSK-3 beta activity attenuates proliferation of human colon cancer cells in rodents

The authors' recent discovery that glycogen synthase kinase-3beta (GSK-3beta) participates in colon cancer cells' survival and proliferation prompted us to investigate whether GSK-3beta inhibition alters proliferation of colon cancer cells in vivo. Groups of four or five athymic mice (Balb/c, nu/nu) with subcutaneous xenografts of SW480 human colon cancer cells were treated with dimethyl sulfoxide (DMSO) or different doses (1, 2 and 5 mg/kg body weight) of either small-molecule GSK-3beta inhibitor (SB-216763 and AR-A014418) by intraperitoneal injection three times per week for 5 weeks. Compared with DMSO (a diluent of the GSK-3beta inhibitors) as a control, either GSK-3beta inhibitor significantly inhibited proliferation of cancer cell xenografts in the rodents in a dose-dependent manner. Histochemical and immunohistochemical analysis of tumor xenografts demonstrated a significant, dose-dependent decrease in fractions of proliferating cells and an increase in the incidence of apoptosis of cancer cells in mice treated with either GSK-3beta inhibitor. No adverse events or effects were observed in the rodents during the course of treatment, except for rare lethal accidents due to intraperitoneal injection. Morphological examination showed no apparent pathologic changes in major organs including the lungs, liver, pancreas, kidneys, spleen and large bowel of rodents treated with DMSO and the GSK-3beta inhibitors. The results indicate that the GSK-3beta inhibitors would be a novel class of therapeutic agent for colon cancer.

The bisphosphonate YM529 inhibits osteoblastic bone tumor proliferation of prostate cancer

BACKGROUND

In men, prostate cancer frequently metastasizes to the bones, where it forms osteoblastic lesions with an osteolytic element that cause pain. However, the role of osteoclastogenesis in bone metastasis of human prostate cancer is unknown. Bisphosphonates are already known to be beneficical for treating osteolytic bone metastases, so we employed a model of osteoblastic bone tumor of human prostate cancer to investigate whether a new bisphosphonate (YM529: minodronate) could inhibit both the formation of bone tumors and the progression of established osteoblastic tumors.

METHODS

Human prostate cancer cells (LNCaP) were injected into adult human bone implants in nonobese diabetic/severe combined immunodeficient mice, after which osteoblastic bone tumors developed. YM529 (1 microg/day) was administered subcutaneously every day for 2 weeks, starting either immediately or 2 weeks after implantation of the tumor cells, and the mice were sacrificed at 4 weeks after implantation. The bone tumors were examined histologically and the number of tartrate-resistant acid phosphatase-stained osteoclasts in each tumor focus was counted.

RESULTS

Histomorphometric analysis revealed that YM529 markedly inhibited both the formation of bone tumors and the progression of established tumors, as well as markedly reducing the number of osteoclasts.

CONCLUSIONS

YM529 reduced the tumor burden in bone by inhibiting both the formation of new lesions and the progression of existing tumors, suggesting that osteoclasts are involved in the formation of bone tumors by prostate cancer. Treatment with this bisphosphonate may potentially be beneficial for patients with bone metastases of prostate cancer.

N-(4-iodophenyl)-N'-(2-chloroethyl)urea as a microtubule disrupter: in vitro and in vivo profiling of antitumoral activity on CT-26 murine colon carcinoma cell line cultured and grafted to mice

The antitumoral profile of the microtubule disrupter N-(4-iodophenyl)-N′-(2-chloroethyl)urea (ICEU) was characterised in vitro and in vivo using the CT-26 colon carcinoma cell line, on the basis of the drug uptake by the cells, the modifications of cell cycle, and β-tubulin and lipid membrane profiles. N-(4-iodophenyl)-N′-(2-chloroethyl)urea exhibited a rapid and dose-dependent uptake by CT-26 cells suggesting its passive diffusion through the membranes. Intraperitoneally injected ICEU biodistributed into the grafted CT-26 tumour, resulting thus in a significant tumour growth inhibition (TGI). N-(4-iodophenyl)-N′-(2-chloroethyl)urea was also observed to accumulate within colon tissue. Tumour growth inhibition was associated with a slight increase in the number of G2 tetraploid tumour cells in vivo, whereas G2 blockage was more obvious in vitro. The phenotype of β-tubulin alkylation that was clearly demonstrated in vitro was undetectable in vivo. Nuclear magnetic resonance analysis showed that cells blocked in G2 phase underwent apoptosis, as confirmed by an increase in the methylene group resonance of mobile lipids, parallel to sub-G1 accumulation of the cells. In vivo, a decrease of the signals of both the phospholipid precursors and the products of membrane degradation occurred concomitantly with TGI. This multi-analysis established, at least partly, the ICEU activity profile, in vitro and in vivo, providing additional data in favour of ICEU as a tubulin-interacting drug accumulating within the intestinal tract. This may provide a starting point for researches for future efficacious tubulin-interacting drugs for the treatment of colorectal cancers.

Lung metastatic load limitation with hyperbaric oxygen

Despite some theoretical concern about cancer-enhancing effects ofhyperbaric oxygen (HBO2) therapy, it is frequently administered to cancer patients. We evaluated the growth of murine breast cancer cells in the lung after hyperbaric oxygen treatment in an experimental metastasis assay. Young nu/nu mice were injected intravenously with 3 x 10(3) 4T1-GFP tumor cells per g body weight followed by lung isolation, perfusion, and intact organ epifluorescence microscopy 1 to 37 days after injection. A group of animals (n=32) was exposed once daily for 5 days a week to 45 min of 2.8 ATA hyperbaric oxygen (HBO2) in a research animal HBO2 chamber. Control animals (n=31) were not subjected to HBO2 treatment, but received similar intravenous administration of 3 x 10(3) 4T 1-GFP tumor cells. Single tumor cells and colonies were counted in the subpleural vessels in areas of about 0.5 cm2 of lung surface. HBO2 treatment did not lead to an increase in the number of the large or small colonies in the lungs. Rather, a significant reduction in the number of the large colonies was observed at 1 and 16 to 21-day periods of measurements after hyperbaric treatment. However, most importantly, there was a significant decrease in large colony size in the HBO2 group during all periods of observation. The results indicate that HBO2 is not prometastatic for breast cancer cells; rather it restricts the growth of large tumor cell colonies.

Multimodality imaging of tumor xenografts and metastases in mice with combined small-animal PET, small-animal CT, and bioluminescence imaging

Recent developments have established molecular imaging of mouse models with small-animal PET and bioluminescence imaging (BLI) as an important tool in cancer research. One of the disadvantages of these imaging modalities is the lack of anatomic information. We combined small-animal PET and BLI technology with small-animal CT to obtain fusion images with both molecular and anatomic information.

METHODS

We used small-animal PET/CT and BLI to detect xenografts of different cell lines and metastases of a melanoma cell line (A375M-3F) that had been transduced with a lentiviral vector containing a trimodality imaging reporter gene encoding a fusion protein with Renilla luciferase, monomeric red fluorescent protein, and a mutant herpes simplex virus type 1 thymidine kinase.

RESULTS

Validation studies in mouse xenograft models showed a good coregistration of images from both PET and CT. Melanoma metastases were detected by 18F-FDG PET, 9-[4-(18)F-fluoro-3-(hydroxymethyl)butyl]guanine (18F-FHBG) PET, CT, and BLI and confirmed by ex vivo assays of Renilla luciferase and mutant thymidine kinase expression. 18F-FHBG PET/CT allowed detection and localization of lesions that were not seen on CT because of poor contrast resolution and were not seen on 18F-FDG PET because of higher background uptake relative to 18F-FHBG.

CONCLUSION

The combination of 18F-FHBG PET, small-animal CT, and BLI allows a sensitive and improved quantification of tumor burden in mice. This technique is potentially useful for the study of the biologic determinants of metastasis and for the evaluation of novel cancer treatments.

Enhanced expression of LKB1 in breast cancer cells attenuates angiogenesis, invasion, and metastatic potential

LKB1 (also known as STK11) is a recently identified tumor suppressor gene whose mutation can lead to Peutz-Jeghers syndrome, which is characterized by gastrointestinal polyps and cancers of different organ systems. Approximately 30% of sporadic breast cancer samples express low levels of LKB1. This suggests that the LKB1 gene may be related to the tumorigenesis of breast cancer. We reintroduced LKB1 into MDA-MB-435 breast cancer cells that lack the LKB1 gene to investigate how overexpression of LKB1 affects tumor invasiveness and metastasis. Overexpression of the LKB1 protein in breast cancer cells resulted in significant inhibition of in vitro invasion. In vivo, LKB1 expression reduced tumor growth in the mammary fat pad, microvessel density, and lung metastasis. LKB1 overexpression was associated with down-regulation of matrix metalloproteinase-2, matrix metalloproteinase-9, vascular endothelial growth factor, and basic fibroblast growth factor mRNA and protein levels. Overexpression of the LKB1 protein in human breast cancer is significantly associated with a decrease in microvessel density. Our results indicate that LKB1 plays a negative regulatory role in human breast cancer, a finding that may lead to a new therapeutic strategy.

Characterization of CD133+ hepatocellular carcinoma cells as cancer stem/progenitor cells

The CD133 antigen, identified as a hematopoietic stem cell marker, appears in various human embryonic epithelia including the neural tube, gut, and kidney. We herein investigated whether CD133(+) cells isolated from human hepatocellular carcinoma cell lines possess cancer stem/progenitor cell-like properties. Among the three cell lines studied, the CD133 antigen was found to be expressed only on the surface of Huh-7 cells. CD133(+) cells from Huh-7 performed a higher in vitro proliferative potential and lower mRNA expressions of mature hepatocyte markers, glutamine synthetase and cytochrome P450 3A4, than CD133(-) population of Huh-7 cells. When either CD133(+) or CD133(-) cells were subcutaneously injected into SCID mice, CD133(+) cells formed tumors, whereas CD133(-) cells induced either a very small number of tumors or none at all. Taken together, the identification of CD133(+) cells could thus be a potentially powerful tool to investigate the tumorigenic process in the hepatoma system and to also develop effective therapies targeted against hepatocellular carcinoma.

Chemokine-mediated migration of melanoma cells towards lymphatics--a mechanism contributing to metastasis

The mechanisms that cause tumors such as melanomas to metastasize into peripheral lymphatic capillaries are poorly defined. Non-mutually-exclusive mechanisms are lymphatic endothelial cell (LEC) chemotaxis and proliferation in response to tumor cells (chemotaxis-lymphangiogenesis hypothesis) or LECs may secrete chemotactic agents that attract cancer cells (chemotactic metastasis hypothesis). Using migration assays, we found evidence supporting both hypotheses. Conditioned medium (CM) from metastatic malignant melanoma (MMM) cell lines attracted LEC migration, consistent with the lymphangiogenesis hypothesis. Conversely, CM from mixed endothelial cells or LECs, but not blood endothelial cells, attracted MMM cells but not non-metastatic melanoma cells, consistent with the chemotactic metastasis hypothesis. MMM cell lines expressed CCR7 receptors for the lymphatic chemokine CCL21 and CCL21 neutralizing antibodies prevented MMM chemotaxis in vitro. To test for chemotactic metastasis in vivo tumor cells were xenotransplanted into nude mice approximately 1 cm from an injected LEC depot. Two different MMM grew directionally towards the LECs, whereas non-metastatic melanomas did not. These observations support the hypothesis that MMM cells grow towards regions of high LEC density owing to chemotactic LEC secretions, including CCL21. This chemotactic metastasis may contribute to the close association between metastasizing tumor cells and peri-tumor lymphatic density and promote lymphatic invasion.

The Thalidomide Analogue, CC-4047, Induces Apoptosis Signaling and Growth Arrest in Childhood Acute Lymphoblastic Leukemia Cells In vitro and In vivo

PURPOSE

Thalidomide and its analogues have shown promise in the treatment of multiple myeloma but their therapeutic potential has not been evaluated in models of acute lymphoblastic leukemia (ALL).

EXPERIMENTAL DESIGN

We assessed the effects of the thalidomide analogue, CC-4047, on the growth and apoptosis signaling of human B cell precursor (BCP) ALL cell lines and freshly obtained childhood BCP-ALL cells grown with or without stromal cells. In addition, we studied the effects of CC-4047 on the progression and dissemination of xenotransplanted human BCP-ALL cells in nonobese diabetic/severe combined immunodeficiency mice.

RESULTS

CC-4047 reduced the proliferation of human BCP-ALL cell lines in vitro. In contrast with the antileukemic effect of cytarabin, this was more pronounced when cell lines or freshly obtained childhood BCP-ALL cells were cocultured with stromal cells. CC-4047 induced the cleavage of caspase-3, caspase-9, and poly(ADP-ribose) polymerase in stroma-cocultured BCP-ALL cells. The inhibition of tumor growth, caspase-3 cleavage, and reduced microvessel density was observed in nonobese diabetic/severe combined immunodeficiency mice inoculated s.c. with childhood BCP-ALL cells upon CC-4047 treatment. After i.v. BCP-ALL xenotransplantation, CC-4047 reduced splenic dissemination.

CONCLUSIONS

The thalidomide analogue, CC-4047, displays profound cytostatic effects on stroma-supported human ALL cells both in vitro and in vivo.

Human glioblastoma biopsy spheroids xenografted into the nude rat brain show growth inhibition after stereotactic radiosurgery

BACKGROUND

The Gamma Knife is currently used to boost treatment of malignant gliomas. However, few experimental studies have focused on its radiobiological effects. In this work, the growth and invasiveness of human glioblastoma spheroids xenografted into nude rat brains were assessed after radiosurgery. Temporary in vitro as well as long-term in vivo radiation effects were studied.

METHODS

Glioblastoma biopsy spheroids were irradiated with 12 or 24 Gy. Short-term in vitro spheroid viability and tumour cell migration was determined by microscopic techniques. Pre-irradiated glioblastoma spheroids were implanted into brains of immunosuppressed rats. Long-term tumour development was assessed by magnetic resonance (MR) imaging, and animal survival was recorded. An immunohistochemical analysis was performed on the sectioned rat brains.

RESULTS

Both un-irradiated and irradiated spheroids remained viable during 2 months in culture, but a dose-dependent inhibition of tumour growth and migration was seen. MR imaging 4 weeks after implantation also showed a dose-dependent inhibition in tumour development. Median animal survival times were 25.5 days (control group), 43 days (12 Gy group) and 96 days (24 Gy group). The study of in vivo long-term radiation effects on the remaining viable tumour population showed no difference in Ki-67 labelling index and microvascular density before and after radiosurgery.

CONCLUSIONS

A dose-dependent inhibition of tumour growth and invasion, as well as a dose-dependent increase in animal survival was observed. The model system described is well suited for assessing the radiobiological effects of Gamma Knife radiosurgery. The results indicate that radiosurgery of malignant gliomas might be effective in controlling tumour progression in selected glioblastoma patients.

Subcutaneous and intrahepatic growth of human hepatoblastoma in immunodeficient mice

BACKGROUND/AIMS

Hepatoblastoma is the most frequent malignant pediatric liver tumor. Approximately 25% of hepatoblastoma patients cannot be cured with current treatment protocols. Additional treatment options must, therefore, be developed. Subcutaneous animal models for hepatoblastoma exist, but a more physiologic intrahepatic model is lacking.

METHODS

The alpha-fetoprotein-expressing hepatoblastoma-cell lines HepT1, HuH6 and the childhood hepatocellular carcinoma-cell line HepG2 were injected subcutaneously and intrasplenically into NMRI nu/nu mice. Tumor growth was monitored by measuring tumor size for subcutaneous and serum human alpha-fetoprotein levels for intra-abdominal tumors. Tumors were characterized microscopically.

RESULTS

Subcutaneous tumor growth occurred in 70% (7/10) of mice injected with HuH6 and 50% (5/10) of mice injected with HepG2. HepT1 did not form tumors. Accumulation of serum alpha-fetoprotein reflected tumor growth. Intrasplenic growth was seen in 50% (14/27, HuH6) and 10% (3/10, HepG2) of the mice, with only HuH6 forming intrahepatic tumors in 25% (7/27) of the mice. Growth pattern and alpha-fetoprotein production were similar at the subcutaneous and intra-abdominal location. Intrahepatic grafting occurred by metastatic spread from the spleen, produced well-defined nodules, and was accompanied by a weakened expression of the hepatocyte marker carbamoylphosphate synthetase, and the canalicular markers CD10 and cytokeratin7. The expression of cytokeratin18 and -19, active caspase3, and beta-catenin was increased. There were no lung metastases.

CONCLUSIONS

We established an intrahepatic mouse model for human hepatoblastoma, in which tumor growth could be monitored by serum alpha-fetoprotein levels. Engrafting in the liver occurred by metastatic spread from the spleen and was accompanied by some loss of differentiation features.