Lentiviral-Induced Spinal Cord Gliomas in Rat Model

Intramedullary spinal cord tumors are a rare and understudied cancer with poor treatment options and prognosis. Our prior study used a combination of PDGF-B, HRAS, and p53 knockdown to induce the development of high-grade glioma in the spinal cords of minipigs. In this study, we evaluate the ability of each vector alone and combinations of vectors to produce high-grade spinal cord gliomas. Eight groups of rats (n = 8/group) underwent thoracolumbar laminectomy and injection of lentiviral vector in the lateral white matter of the spinal cord. Each group received a different combination of lentiviral vectors expressing PDGF-B, a constitutively active HRAS mutant, or shRNA targeting p53, or a control vector. All animals were monitored once per week for clinical deficits for 98 days. Tissues were harvested and analyzed using hematoxylin and eosin (H&E) and immunohistochemical (IHC) staining. Rats injected with PDGF-B+HRAS+sh-p53 (triple cocktail) exhibited statistically significant declines in all behavioral measures (Basso Beattie Bresnahan scoring, Tarlov scoring, weight, and survival rate) over time when compared to the control. Histologically, all groups except the control and those injected with sh-p53 displayed the development of tumors at the injection site, although there were differences in the rate of tumor growth and the histopathological features of the lesions between groups. Examination of immunohistochemistry revealed rats receiving triple cocktail displayed the largest and most significant increase in the Ki67 proliferation index and GFAP positivity than any other group. PDGF-B+HRAS also displayed a significant increase in the Ki67 proliferation index. Rats receiving PDGF-B alone and PDGF-B+ sh-p53 displayed more a significant increase in SOX2-positive staining than in any other group. We found that different vector combinations produced differing high-grade glioma models in rodents. The combination of all three vectors produced a model of high-grade glioma more efficiently and aggressively with respect to behavioral, physiological, and histological characteristics than the rest of the vector combinations. Thus, the present rat model of spinal cord glioma may potentially be used to evaluate therapeutic strategies in the future.

Systemic muscle wasting and coordinated tumour response drive tumourigenesis

Cancer cells demand excess nutrients to support their proliferation, but how tumours exploit extracellular amino acids during systemic metabolic perturbations remain incompletely understood. Here, we use a Drosophila model of high-sugar diet (HSD)-enhanced tumourigenesis to uncover a systemic host-tumour metabolic circuit that supports tumour growth. We demonstrate coordinate induction of systemic muscle wasting with tumour-autonomous Yorkie-mediated SLC36-family amino acid transporter expression as a proline-scavenging programme to drive tumourigenesis. We identify Indole-3-propionic acid as an optimal amino acid derivative to rationally target the proline-dependency of tumour growth. Insights from this whole-animal Drosophila model provide a powerful approach towards the identification and therapeutic exploitation of the amino acid vulnerabilities of tumourigenesis in the context of a perturbed systemic metabolic network.

A Distinct Role of the Autonomic Nervous System in Modulating the Function of Lymphatic Vessels under Physiological and Tumor-Draining Conditions

Lymphatic vessels (LVs) are important in the regulation of tissue fluid homeostasis and the pathogenesis of tumor progression. We investigated the innervation of LVs and the response to agonists and antagonists of the autonomic nervous system in vivo. While skin-draining collecting LVs express muscarinic, α₁- and β₂-adrenergic receptors on lymphatic endothelial cells and smooth muscle cells, intestinal lacteals express only β-adrenergic receptors and muscarinic receptors on their smooth muscle cells. Quantitative in vivo near-infrared imaging of the exposed flank-collecting LV revealed that muscarinic and α₁-adrenergic agonists increased LV contractility, whereas activation of β₂-adrenergic receptors inhibited contractility and initiated nitric oxide (NO)-dependent vasodilation. Tumor-draining LVs were expanded and showed a higher innervation density and contractility that was reduced by treatment with atropine, phentolamine, and, most potently, isoproterenol. These findings likely have clinical implications given the impact of lymphatic fluid drainage on intratumoral fluid pressure and thus drug delivery.

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Murine lymphatic vessels are innervated in an organ-specific manner

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α₁-adrenergic and muscarinic agents enhance lymphatic contractility in vivo

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β₂-adrenergic agents reduce lymphatic contractility

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Tumor-draining lymphatic vessels have increased innervation and contractility

Pathogenesis of peritumoral hyperexcitability in an immunocompetent CRISPR-based glioblastoma model

Seizures often herald the clinical appearance of gliomas or appear at later stages. Dissecting their precise evolution and cellular pathogenesis in brain malignancies could inform the development of staged therapies for these highly pharmaco-resistant epilepsies. Studies in immunodeficient xenograft models have identified local interneuron loss and excess glial glutamate release as chief contributors to network disinhibition, but how hyperexcitability in the peritumoral microenvironment evolves in an immunocompetent brain is unclear. We generated gliomas in WT mice via in utero deletion of key tumor suppressor genes and serially monitored cortical epileptogenesis during tumor infiltration with in vivo electrophysiology and GCAMP7 calcium imaging, revealing a reproducible progression from hyperexcitability to convulsive seizures. Long before seizures, coincident with loss of inhibitory cells and their protective scaffolding, gain of glial glutamate antiporter xCT expression, and reactive astrocytosis, we detected local Iba1+ microglial inflammation that intensified and later extended far beyond tumor boundaries. Hitherto unrecognized episodes of cortical spreading depolarization that arose frequently from the peritumoral region may provide a mechanism for transient neurological deficits. Early blockade of glial xCT activity inhibited later seizures, and genomic reduction of host brain excitability by deleting MapT suppressed molecular markers of epileptogenesis and seizures. Our studies confirmed xenograft tumor-driven pathobiology and revealed early and late components of tumor-related epileptogenesis in a genetically tractable, immunocompetent mouse model of glioma, allowing the complex dissection of tumor versus host pathogenic seizure mechanisms.

Induced sensitivity to EGFR inhibitors is mediated by palmitoylated cysteine 1025 of EGFR and requires oncogenic Kras

Currently, there are no effective therapeutic strategies targeting Kras driven cancers, and therefore, identifying new targeted therapies and overcoming drug resistance have become paramount for effective long-term cancer therapy. We have found that reducing expression of the palmitoyl transferase DHHC20 increases cell death induced by the EGFR inhibitor gefitinib in Kras and EGFR mutant cell lines, but not MCF7 cells harboring wildtype Kras. We show that the increased gefitinib sensitivity in cancer cells induced by DHHC20 inhibition is mediated directly through loss of palmitoylation on a previously identified cysteine residue in the C-terminal tail of EGFR. We utilized an EGFR point mutant in which the palmitoylated cysteine 1025 is mutated to alanine (EGFR^C1025A), that results in receptor activation. Expression of the EGFR mutant alone in NIH3T3 cells does not increase sensitivity to gefitinib-induced cell death. However, when EGFR^C1025A is expressed in cells expressing activated Kras^G12V, EGFR inhibitor induced cell death is increased. Surprisingly, lung cancer cells harboring the EGFR inhibitor resistant mutation, T790M, become sensitive to EGFR inhibitor treatment when DHHC20 is inhibited. Finally, the small molecule, 2-bromopalmitate, which has been shown to inhibit palmitoyl transferases, acts synergistically with gefitinib to induce cell death in the gefitinib resistant cell line NCI-H1975.

Absolute quantification of acetylation and phosphorylation of the histone variant H2AX upon ionizing radiation reveals distinct cellular responses in two cancer cell lines

Histone modifications change upon the cellular response to ionizing radiation, and their cellular amounts could reflect the DNA damage response activity. We previously reported a sensitive and reliable method for the absolute quantification of γH2AX within cells, using liquid chromatography-tandem mass spectrometry (LC/MS/MS). The technique has broad adaptability to a variety of biological systems and can quantitate different modifications of histones. In this study, we applied it to quantitate the levels of γH2AX and K5-acetylated H2AX, and to compare the radiation responses between two cancer cell lines: HeLa and U-2 OS. The two cell lines have distinct properties in terms of their H2AX modifications. HeLa cells have relatively high γH2AX (3.1 %) against the total H2AX even in un-irradiated cells, while U-2 OS cells have an essentially undetectable level (nearly 0 %) of γH2AX. In contrast, the amounts of acetylated histones are lower in HeLa cells (9.3 %) and higher in U-2 OS cells (24.2 %) under un-irradiated conditions. Furthermore, after ionizing radiation exposure, the time-dependent increases and decreases in the amounts of histone modifications differed between the two cell lines, especially at the early time points. These results suggest that each biological system has distinct kinase/phosphatase and/or acetylase/deacetylase activities. In conclusion, for the first time, we have succeeded in simultaneously monitoring the absolute amounts of phosphorylated and acetylated cellular H2AX after ionizing radiation exposure. This multi-criteria assessment enables precise comparisons of the effects of radiation between any biological systems.

The motility-proliferation-metabolism interplay during metastatic invasion

Metastasis is the major cause for cancer patients' death, and despite all the recent advances in cancer research it is still mostly incurable. Understanding the mechanisms that are involved in the migration of the cells in a complex environment is a key step towards successful anti-metastatic treatment. Using experimental data-based modeling, we focus on the fundamentals of metastatic invasion: motility, invasion, proliferation and metabolism, and study how they may be combined to maximize the cancer's ability to metastasize. The modeled cells' performance is measured by the number of cells that succeed in migration in a maze, which mimics the extracellular environment. We show that co-existence of different cell clones in the tumor, as often found in experiments, optimizes the invasive ability in a frequently-changing environment. We study the role of metabolism and stimulation by growth factors, and show that metabolism plays a crucial role in the metastatic process and should therefore be targeted for successful treatment.

3D Silicon Microstructures: A New Tool for Evaluating Biological Aggressiveness of Tumor Cells

In this work, silicon micromachined structures (SMS), consisting of arrays of 3- μ m-thick silicon walls separated by 50- μm-deep, 5- μ m-wide gaps, were applied to investigate the behavior of eight tumor cell lines, with different origins and biological aggressiveness, in a three-dimensional (3D) microenvironment. Several cell culture experiments were performed on 3D-SMS and cells grown on silicon were stained for fluorescence microscopy analyses. Most of the tumor cell lines recognized in the literature as highly aggressive (OVCAR-5, A375, MDA-MB-231, and RPMI-7951) exhibited a great ability to enter and colonize the narrow deep gaps of the SMS, whereas less aggressive cell lines (OVCAR-3, Capan-1, MCF7, and NCI-H2126) demonstrated less penetration capability and tended to remain on top of the SMS. Quantitative image analyses of several fluorescence microscopy fields of silicon samples were performed for automatic cell recognition and count, in order to quantify the fraction of cells inside the gaps, with respect to the total number of cells in the examined field. Our results show that higher fractions of cells in the gaps are obtained with more aggressive cell lines, thus supporting in a quantitative way the observation that the behavior of tumor cells on the 3D-SMS depends on their aggressiveness level.

Optimization of arterial spin labeling MRI for quantitative tumor perfusion in a mouse xenograft model

Perfusion is an important biomarker of tissue function and has been associated with tumor pathophysiology such as angiogenesis and hypoxia. Arterial spin labeling (ASL) MRI allows noninvasive and quantitative imaging of perfusion; however, the application in mouse xenograft tumor models has been challenging due to the low sensitivity and high perfusion heterogeneity. In this study, flow-sensitive alternating inversion recovery (FAIR) ASL was optimized for a mouse xenograft tumor. To assess the sensitivity and reliability for measuring low perfusion, the lumbar muscle was used as a reference region. By optimizing the number of averages and inversion times, muscle perfusion as low as 32.4 ± 4.8 (mean ± standard deviation) ml/100 g/min could be measured in 20 min at 7 T with a quantification error of 14.4 ± 9.1%. Applying the optimized protocol, heterogeneous perfusion ranging from 49.5 to 211.2 ml/100 g/min in a renal carcinoma was observed. To understand the relationship with tumor pathology, global and regional tumor perfusion was compared with histological staining of blood vessels (CD34), hypoxia (CAIX) and apoptosis (TUNEL). No correlation was observed when the global tumor perfusion was compared with these pathological parameters. Regional analysis shows that areas of high perfusion had low microvessel density, which was due to larger vessel area compared with areas of low perfusion. Nonetheless, these were not correlated with hypoxia or apoptosis. The results suggest that tumor perfusion may reflect certain aspect of angiogenesis, but its relationship with other pathologies needs further investigation.

Bioreactor-engineered cancer tissue-like structures mimic phenotypes, gene expression profiles and drug resistance patterns observed "in vivo"

Anticancer compound screening on 2D cell cultures poorly predicts "in vivo" performance, while conventional 3D culture systems are usually characterized by limited cell proliferation, failing to produce tissue-like-structures (TLS) suitable for drug testing. We addressed engineering of TLS by culturing cancer cells in porous scaffolds under perfusion flow. Colorectal cancer (CRC) HT-29 cells were cultured in 2D, on collagen sponges in static conditions or in perfused bioreactors, or injected subcutaneously in immunodeficient mice. Perfused 3D (p3D) cultures resulted in significantly higher (p < 0.0001) cell proliferation than static 3D (s3D) cultures and yielded more homogeneous TLS, with morphology and phenotypes similar to xenografts. Transcriptome analysis revealed a high correlation between xenografts and p3D cultures, particularly for gene clusters regulating apoptotic processes and response to hypoxia. Treatment with 5-Fluorouracil (5-FU), a frequently used but often clinically ineffective chemotherapy drug, induced apoptosis, down-regulation of anti-apoptotic genes (BCL-2, TRAF1, and c-FLIP) and decreased cell numbers in 2D, but only "nucleolar stress" in p3D and xenografts. Conversely, BCL-2 inhibitor ABT-199 induced cytotoxic effects in p3D but not in 2D cultures. Our findings advocate the importance of perfusion flow in 3D cultures of tumor cells to efficiently mimic functional features observed "in vivo" and to test anticancer compounds.

Multidistance diffuse correlation spectroscopy for simultaneous estimation of blood flow index and optical properties

Traditionally, diffuse correlation spectroscopy (DCS) measures microvascular blood flow by fitting a physical model to the measurement of the intensity autocorrelation function from a single source-detector pair. This analysis relies on the accurate knowledge of the optical properties, absorption, and reduced scattering coefficients of the medium. Therefore, DCS is often deployed together with diffuse optical spectroscopy. We present an algorithm that employs multidistance DCS (MD-DCS) for simultaneous measurement of bloodflow index, as well as an estimate of the optical properties of the tissue. The algorithm has been validated through noise-free and noise-added simulated data and phantom measurements. A longitudinal in vivo measurement ofa mouse tumor is also shown. MD-DCS is introduced as a stand-alone system for small source-detector separations (<2 cm) for noninvasive measurement of microvascular blood flow.

Modeling tumor microenvironments in vitro

Tumor progression depends critically upon the interactions between the tumor cells and their microenvironment. The tumor microenvironment is heterogeneous and dynamic; it consists of extracellular matrix, stromal cells, immune cells, progenitor cells, and blood and lymphatic vessels. The emerging fields of tissue engineering and microtechnologies have opened up new possibilities for engineering physiologically relevant and spatially well-defined microenvironments. These in vitro models allow specific manipulation of biophysical and biochemical parameters, such as chemical gradients, biomatrix stiffness, metabolic stress, and fluid flows; thus providing a means to study their roles in certain aspects of tumor progression such as cell proliferation, invasion, and crosstalk with other cell types. Challenges and perspectives for deconvolving the complexity of tumor microenvironments will be discussed. Emphasis will be given to in vitro models of tumor cell migration and invasion.

Quantitative estimation of DNA damage by photon irradiation based on the microdosimetric-kinetic model

The microdosimetric-kinetic (MK) model is one of the models that can describe the fraction of cells surviving after exposure to ionizing radiation. In the MK model, there are specific parameters, k and yD, where k is an inherent parameter to represent the number of potentially lethal lesions (PLLs) and yD indicates the dose-mean lineal energy in keV/μm. Assuming the PLLs to be DNA double-strand breaks (DSBs), the rate equations are derived for evaluating the DSB number in the cell nucleus. In this study, we estimated the ratio of DSBs for two types of photon irradiation (6 MV and 200 kVp X-rays) in Chinese hamster ovary (CHO-K1) cells and human non-small cell lung cancer (H1299) cells by observing the surviving fraction. The estimated ratio was then compared with the ratio of γ-H2AX foci using immunofluorescent staining. For making a comparison of the number of DSBs among a variety of radiation energy cases, we next utilized the survival data in the literature for both cells exposed to other photon types, such as (60)Co γ-rays, (137)Cs γ-rays and 100 kVp X-rays. The ratio of DSBs based on the MK model with conventional data was consistent with the ratio of γ-H2AX foci numbers, confirming that the γ-H2AX focus is indicative of DSBs. It was also shown that the larger yD is, the larger the DSB number is. These results suggest that k and yD represent the characteristics of the surviving fraction and the biological effects for photon irradiation.

Applicability of the linear-quadratic model to single and fractionated radiotherapy schedules: an experimental study

The aim of this study was to examine the applicability of the linear-quadratic (LQ) model to single and fractionated irradiation in EMT6 cells. First, the α/β ratio of the cells was determined from single-dose experiments, and a biologically effective dose (BED) for 20 Gy in 10 fractions (fr) was calculated. Fractional doses yielding the same BED were calculated for 1-, 2-, 3-, 4-, 5-, 7-, 15- and 20-fraction irradiation using LQ formalism, and then irradiation with these schedules was actually given. Cell survival was determined by a standard colony assay. Differences in cell survival between pairs of groups were compared by t-test. The α/β ratio of the cells was 3.18 Gy, and 20 Gy in 10 fr corresponded to a BED3.18 of 32.6 Gy. The effects of 7-, 15- and 20-fraction irradiation with a BED3.18 of 32.6 Gy were similar to those of the 10-fraction irradiation, while the effects of 1- to 5-fraction irradiation were lower. In this cell line, the LQ model was considered applicable to 7- to 20-fraction irradiation or doses per fraction of 2.57 Gy or smaller. The LQ model might be applicable in the dose range below the α/β ratio.

Three monofunctional copolymers into one multifunctional Micelle: Part 1. Preparation and properties

In the present work, we propose a new multifunctional micelle, co-self-assembled from different monofunctional copolymers, for tumor targeting and fluorescent and electron spin resonance (ESR) dual detection. Firstly, a poly(D,L-lactic acid)-b-poly(N-isopropyl methacrylamide-co-N-isopropylmaelic acid-co-10-undecenoic acid)-b-poly(N-acryloxysuccinimide) (PLA-PNNUA-PNAS) copolymer, with pH-dependent thermo-responsive properties, was synthesized. The copolymer was synthesized using reversible addition fragmentation chain transfer (RAFT) polymerization method, after which it was further used as a parent copolymer to combine with folic acid (FA), fluorescein isothiocyanate (FITC) and 4-amino-2,2,6,6-tetramethylpiperidin-1-oxyl (4-NH2-TEMPO), respectively, resulting into three new monofunctional copolymers. Finally, the multifunctional copolymer micelle was easily then fabricated, through co-self-assembly, using the monofunctional copolymers. The results from in vitro cell assays indicated that the proposed micelle was able to provide desired multifunctional properties, including tumor specific targeting and fluorescent and ESR dual detection. Additionally, the parent copolymer allowed conjugation with other ligands to prepare them for more functional copolymers attachment for future potential applications. More importantly, the multifunctional properties of the copolymer micelles could be rationally tailored, able for given purposes.

[Light-induced disruption of the circadian clock and risk of malignant tumors in laboratory animals: state of the problem]

There were obtained sufficient experimental evidence of the stimulating effect on the development of tumors (transplanted, spontaneous and induced by various carcinogenic agents), disorders of circadian function of the pineal gland (light-induced desynchronosis) caused by knockout or mutation of clock genes, pinealectomy, content in conditions of constant light or natural light regime of the North, as well as jetlag modeling in laboratory rodents. In experiments on various models of carcinogenesis it was found that sympathectomy (removal of the superior cervical ganglion), light deprivation, hibernation and application of melatonin, the natural hormone of the pineal gland, had an inhibitory effect on the development of transplanted, spontaneous and induced tumors of different histogenesis.

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.

Contrast enhanced ultrasonography (CEUS) in the characterization of tumor microcirculation. Validation of the procedure in the animal experimental model

AIM

The aims of this study are the development of a contrast enhanced ultrasonography (CEUS) protocol for rats' evaluation and the assessment of the potential benefits of CEUS in Walker 256 tumor rats.

MATERIAL AND METHOD

In the study were used 36 albino Wistar rats grafted subcutaneously with Walker 256 tumor. The implementation of the ultrasound (US) guided injection technique (30 subjects - group A) was performed between 4 to 8 weeks after implantation. The contrast agent (CA) - Sono Vue (Bracco) - was administered either into the lateral vein of the tail or directly into the heart under US guidance. The US validation, focusing on CEUS (6 subjects - group B) was realized at 4 to 6 weeks after implantation. The US procedures aimed to obtain morphological (2D), vascular (color Doppler and pulsed Doppler) and angiospecific functional data (CEUS). The Vevo 2100 equipment was used for US and Time Intensity Curves (TIC) were analyzed with Sonoliver (TomTec). The tumor specimens which were resected after the last study underwent a pathology exam.

RESULTS

A number of 23 successfully CEUS explorations were performed in 17 subjects (11 in group A and 6 in group B). Nineteen rats could not be evaluated (in 8 cases the tumor was not viable; 4 subjects died during CA administration; in 4 cases the administration line could not be obtained). In group B, CEUS was performed in 6 subjects at 4 weeks after implantation and in 5 subjects at 6 weeks. The statistical analysis of the TIC parameters identified significant differences between the Time to Peak, mean Transit Time and Rise Time parameters of the muscles and those of the tumor.

CONCLUSIONS

CEUS was easily implemented on the studied tumor model and is adequate for the evaluation of tumor vascularity. US guided intracardiac administration of the CA is an easy and reproducible procedure. If the examination is performed at defined time intervals it detects the alterations within the tumor circulatory bed.

Silica-based branched hollow microfibers as a biomimetic extracellular matrix for promoting tumor cell growth in vitro and in vivo

A novel scaffold composed of loosely branched hollow silica microfibers that has been proven to be highly biocompatible is proposed for the 3D culture of cancer cells. The MCF-7 cancer cells can grow and proliferate freely inside the scaffold in the form of multicellular spheroids. MCF-7 cancer cells cultured on the current 3D silica scaffold retained significantly more oncological characters than those cultured on the conventional 2D substrate and can serve as in vitro tumor model for studying cancer treatment.

A preclinical study to explore vasculature differences between primary and recurrent tumors using ultrasound Doppler imaging

The purpose of this preclinical study was to perform a longitudinal investigation of the function and morphology of the vasculatures of primary and recurrent tumors, because recurrent tumors have lower curability. Thus, elucidating differences in the features of the vasculatures of primary and recurrent tumors could help to improve tumor therapies. The transgenic adenocarcinoma of the mouse prostate tumors were transplanted in nonirradiated and with 25 Gy of preirradiation normal tissues to produce the primary and recurrent tumor models, respectively. The perfusion and branching index of tumor vasculatures were characterized to reveal the function and morphology information, respectively. The blood vessels were more dilated and continuous in recurrent tumors than in primary tumors. During tumor progression, the perfusion increased in primary tumors but did not change significantly in recurrent tumors. The tumor perfusion was lower in recurrent tumors than in primary tumors, whereas branching index in 2-D ultrasound images did not differ between the two tumor models. Furthermore, the introducing 3-D volumetric power Doppler image may have the potential for accurately revealing the morphologic features within tumors. The results of this study suggest that power Doppler imaging is an easily applied and rapid method for noninvasively assessing the vascular features of primary and recurrent tumors and for exploring differences between their vasculature pathways.

Systematic analysis of RBE and related quantities using a database of cell survival experiments with ion beam irradiation

For tumor therapy with light ions and for experimental aspects in particle radiobiology the relative biological effectiveness (RBE) is an important quantity to describe the increased effectiveness of particle radiation. By establishing and analysing a database of ion and photon cell survival data, some remarkable properties of RBE-related quantities were observed. The database consists of 855 in vitro cell survival experiments after ion and photon irradiation. The experiments comprise curves obtained in different labs, using different ion species, different irradiation modalities, the whole range of accessible energies and linear energy transfers (LETs) and various cell types. Each survival curve has been parameterized using the linear-quadratic (LQ) model. The photon parameters, α and β, appear to be slightly anti-correlated, which might point toward an underlying biological mechanism. The RBE values derived from the survival curves support the known dependence of RBE on LET, on particle species and dose. A positive correlation of RBE with the ratio α/β of the photon LQ parameters is found at low doses, which unexpectedly changes to a negative correlation at high doses. Furthermore, we investigated the course of the β coefficient of the LQ model with increasing LET, finding typically a slight initial increase and a final falloff to zero. The observed fluctuations in RBE values of comparable experiments resemble overall RBE uncertainties, which is of relevance for treatment planning. The database can also be used for extensive testing of RBE models. We thus compare simulations with the local effect model to achieve this goal.

Microdosimetric calculation of relative biological effectiveness for design of therapeutic proton beams

The authors attempt to establish the relative biological effectiveness (RBE) calculation for designing therapeutic proton beams on the basis of microdosimetry. The tissue-equivalent proportional counter (TEPC) was used to measure microdosimetric lineal energy spectra for proton beams at various depths in a water phantom. An RBE-weighted absorbed dose is defined as an absorbed dose multiplied by an RBE for cell death of human salivary gland (HSG) tumor cells in this study. The RBE values were calculated by a modified microdosimetric kinetic model using the biological parameters for HSG tumor cells. The calculated RBE distributions showed a gradual increase to about 1cm short of a beam range and a steep increase around the beam range for both the mono-energetic and spread-out Bragg peak (SOBP) proton beams. The calculated RBE values were partially compared with a biological experiment in which the HSG tumor cells were irradiated by the SOBP beam except around the distal end. The RBE-weighted absorbed dose distribution for the SOBP beam was derived from the measured spectra for the mono-energetic beam by a mixing calculation, and it was confirmed that it agreed well with that directly derived from the microdosimetric spectra measured in the SOBP beam. The absorbed dose distributions to planarize the RBE-weighted absorbed dose were calculated in consideration of the RBE dependence on the prescribed absorbed dose and cellular radio-sensitivity. The results show that the microdosimetric measurement for the mono-energetic proton beam is also useful for designing RBE-weighted absorbed dose distributions for range-modulated proton beams.

Facile synthesis of water-dispersible Cu2O nanocrystal-reduced graphene oxide hybrid as a promising cancer therapeutic agent

We report a Cu(2)O nanocrystal-reduced graphene oxide hybrid that is dispersible in water and has anticancer activity under both visible and near-infrared light irradiation. In contrast to the highly efficient killing of both normal and cancer cells initiated by the photothermal effect, the photocatalytic effect of this material results in the selective killing of cancer cells under visible light irradiation. These results have implications for safe and widely applicable cancer therapy agents.

The therapeutic effect of PEI-Mn0.5Zn0.5Fe2O4 nanoparticles/pEgr1-HSV-TK/GCV associated with radiation and magnet-induced heating on hepatoma

Comprehensive therapy based on the integration of hyperthermia, radiation, gene therapy and chemotherapy is a promising area of study in cancer treatment. Using PEI-Mn(0.5)Zn(0.5)Fe(2)O(4) nanoparticles (PEI-MZF-NPs) as a gene transfer vector, the authors transfected self-prepared pEgr1-HSV-TK into HepG2 cells and measured the expression of the exogenous gene HSV-TK by RT-PCR. The results showed that HSV-TK was successfully transfected into HepG2 cells and the expression levels of HSV-TK remained stable. Besides, PEI-MZF-NPs were used as magnetic media for thermotherapy to treat hepatoma by magnet-induced heating, combined with radiation-gene therapy. Both in vitro and in vivo results suggest that this combined treatment with gene, radiation and heating has a better therapeutic effect than any of them alone. The apoptotic rate and necrotic rate of the combined treatment group was 51.84% and 15.45%, respectively. In contrast, it was only 20.55% and 6.80% in the radiation-gene group, 7.49% and 3.62% in the radiation-alone group, 15.23% and 7.90% in the heating-alone group, and only 3.52% and 2.16% in the blank control group. The inhibition rate of cell proliferation (88.5%) of the combined treatment group was significantly higher than that of the radiation-gene group (59.5%), radiation-alone group (37.6%) and heating-alone group (60.6%). The tumor volume and mass inhibition rate of the combined treatment group was 94.45% and 93.38%, respectively, significantly higher than 41.28% and 33.58% of the radiation-alone group, 60.76% and 52.18% of the radiation-gene group, 79.91% and 77.40% of the heating-alone group. It is therefore concluded that this combined application of heating, radiation and gene therapy has a good synergistic and complementary effect and PEI-MZF-NPs can act as a novel non-viral gene vector and magnetic induction medium, which offers a viable approach for the treatment of cancer.

Rationally designed tumor-penetrating nanocomplexes

Small interfering RNA (siRNA) therapeutics have broad potential uses in medicine but require safe and effective delivery vehicles to function. An ideal delivery system should encapsulate and protect the siRNA cargo from serum proteins, exhibit target tissue and cell specificity, penetrate the cell surface, and release its cargo in the desired intracellular compartment. One approach to the design of delivery vehicles that meets all of these requirements utilizes the systematic assembly of multiple components that can address each barrier. This rational approach was adopted by Ren et al., who designed novel myristoylated tandem peptides that consist of a tumor-targeting module and a cell-penetrating module, as described in this issue of ACS Nano. These tandem peptides were formulated with siRNAs into nanocomplexes for cell-specific delivery to a variety of tumor cell lines. The correlation of the structural properties of the nanocomplex to cell-type-specific activity via a computational approach identified the valence of the tumor-targeting ligand and overall nanocomplex charge as important parameters for the activity of the formulations. The in vivo gene silencing potency of these peptide-based nanocomplex formulations was demonstrated by Ren et al. in an ovarian cancer model. Tumor-penetrating nanocomplexes carrying a siRNA sequence against a novel oncogene (ID4) led to a significant reduction in tumor burden and an 80% increase in mouse survival. As such, the combination of a systematic approach with computational modeling can be advantageous for improving the delivery and potency of siRNA therapeutics.

Identification and characterization of receptor-specific peptides for siRNA delivery

Tumor-targeted delivery of siRNA remains a major barrier in fully realizing the therapeutic potential of RNA interference. While cell-penetrating peptides (CPP) are promising siRNA carrier candidates, they are universal internalizers that lack cell-type specificity. Herein, we design and screen a library of tandem tumor-targeting and cell-penetrating peptides that condense siRNA into stable nanocomplexes for cell type-specific siRNA delivery. Through physiochemical and biological characterization, we identify a subset of the nanocomplex library of that are taken up by cells via endocytosis, trigger endosomal escape and unpacking of the carrier, and ultimately deliver siRNA to the cytosol in a receptor-specific fashion. To better understand the structure-activity relationships that govern receptor-specific siRNA delivery, we employ computational regression analysis and identify a set of key convergent structural properties, namely the valence of the targeting ligand and the charge of the peptide, that help transform ubiquitously internalizing cell-penetrating peptides into cell type-specific siRNA delivery systems.

Effects of acetic acid on light scattering from cells

Acetic acid has been used for decades as an aid for the detection of precancerous cervical lesions, and the use of acetic acid is being investigated in several other tissues. Nonetheless, the mechanism of acetowhitening is unclear. This work tests some of the hypotheses in the literature and measures changes in light scattering specific to the nucleus and the cytoplasm. Wide angle side scattering from both the nucleus and the cytoplasm increases with acetic application to tumorigenic cells, with the increase in nuclear scattering being greater. In one cell line, the changes in nuclear scattering are likely due to an increase in number or scattering efficiency of scattering centers smaller than the wavelength of excitation light. There are likely several cellular changes that cause acetowhitening and the cellular changes may differ with cell type. These results should lead to a better understanding of acetowhitening and potentially the development of adjunct techniques to improve the utility of acetic acid application. For the well-studied case of cervical tissue, acetowhitening has been shown to be sensitive, but not specific for oncogenic changes needing treatment.

Tumor inside a pearl drop

The confined internal space of a liquid marble, as well as its porous and non-adhesive shell, offers an attractive application possibility - accommodating living cells inside liquid marbles. Cancer cells in suspension may aggregate to form three dimensional structures, also known as cancer cell spheroids (CCS). In this study, CCS formation inside liquid marble is investigated. This liquid marble application opens significant and novel avenues for biomedical applications and cancer research.

Analgesia targeting IB4-positive neurons in cancer-induced mechanical hypersensitivity

Cancer patients often suffer from pain and most will be prescribed μ-opioids. μ-opioids are not satisfactory in treating cancer pain and are associated with multiple debilitating side effects. Recent studies show that μ and δ opioid receptors are separately expressed on IB4 (-) and IB4 (+) neurons, which control thermal and mechanical pain, respectively. In this study we investigated IB4 (+) and IB4 (-) neurons in mechanical and thermal hypersensitivity in an orthotopic mouse oral cancer model. We used a δ opioid receptor agonist and a P2X(3) antagonist to target IB4 (+) neurons and to demonstrate that this subset plays a key role in cancer-induced mechanical allodynia, but not in thermal hyperalgesia. Moreover, selective removal of IB4 (+) neurons using IB4-saporin impacts cancer-induced mechanical but not thermal hypersensitivity. Our results demonstrate that peripherally administered pharmacological agents targeting IB4 (+) neurons, such as a selective δ-opioid receptor agonist or P2X(3) antagonist, might be useful in treating oral cancer pain.

PERSPECTIVE

To clarify the mechanisms of oral cancer pain, we examined the differential role of IB4 (+) and IB4 (-) neurons. Characterization of these 2 subsets of putative nociceptors is important for further development of effective clinical cancer pain relief.

Novel animal glioma models that separately exhibit two different invasive and angiogenic phenotypes of human glioblastomas

OBJECTIVE

Invasive behaviors of malignant gliomas are fundamental traits and major reasons for treatment failure. Delineation of invasive growth is important in establishing treatment for gliomas and experimental neuro-oncology could benefit from an invasive glioma model. In this study, we established two new cell line-based animal models of invasive glioma.

METHODS

Two cell lines, J3T-1 and J3T-2, were derived from the same parental canine glioma cell line, J3T. These cells were inoculated to establish brain tumors in athymic mice and rats. Pathologic samples of these animal gliomas were examined to analyze invasive patterns in relation to angiogenesis, and were compared with human glioblastoma samples. The molecular profiles of these cell lines were also shown.

RESULTS

Histologically, J3T-1 and J3T-2 tumors exhibited different invasive patterns. J3T-1 cells clustered around newly developed vessels at tumor borders, whereas J3T-2 cells showed diffuse single cell infiltration into surrounding healthy parenchyma. In human malignant glioma samples, both types of invasion were observed concomitantly. Molecular profiles of these cell lines were analyzed by immunocytochemistry and with quantitative reverse transcription polymerase chain reaction. Vascular endothelial growth factor, matrix metalloproteinase-9, hypoxia-inducible factor-1, and platelet-derived growth factor were overexpressed in J3T-1 cells rather than in J3T-2 cells, whereas integrin αvβ3, matrix metalloproteinase-2, nestin, and secreted protein acidic and rich in cysteine were overexpressed in J3T-2 cells rather than in J3T-1 cells.

CONCLUSIONS

These animal models histologically recapitulated two invasive and angiogenic phenotypes, namely angiogenesis-dependent and angiogenesis-independent invasion, also observed in human glioblastoma. These cell lines provided a reproducible in vitro and in vivo system to analyze the mechanisms of invasion and angiogenesis in glioma progression.

Novel insights on imaging sex-hormone-dependent tumourigenesis in vivo

Sex hormones modulate proliferation, apoptosis, migration, metastasis and angiogenesis in cancer cells influencing tumourigenesis from the early hyperplastic growth till the end-stage metastasis. Although decades of studies have detailed these effects at the level of molecular pathways, where and when these actions are needed for the growth and progression of hormone-dependent neoplasia is poorly elucidated. Investigation of the hormone influences in carcinogenesis in the spatio-temporal dimension is expected to unravel critical steps in tumour progression and in the onset of resistance to hormone therapies. Non-invasive in vivo imaging represents a powerful tool to follow in time hormone signalling in the whole body during tumour development. This review summarizes the tools currently available to follow hormone action in living organisms.

Determination of the tumor tissue optical properties during and after photodynamic therapy using inverse Monte Carlo method and double integrating sphere between 350 and 1000 nm

Photodynamic therapy (PDT) efficacy depends on the amount of light distribution within the tissue. However, conventional PDT does not consider the laser irradiation dose during PDT. The optical properties of biological tissues (absorption coefficient μ(a), reduced scattering coefficient μ's), anisotropy factor g, refractive index, etc.) help us to recognize light propagation through the tissue. The goal of this paper is to acquire the knowledge of the light propagation within tissue during and after PDT with the optical property of PDT-performed mouse tumor tissue. The optical properties of mouse tumor tissues were evaluated using a double integrating sphere setup and the algorithm based on the inverse Monte Carlo method in the wavelength range from 350 to 1000 nm. During PDT, the μ(a) and μ's were not changed after 1 and 5 min of irradiation. After PDT, the μ's in the wavelength range from 600 to 1000 nm increased with the passage of time. For seven days after PDT, the μ's increased by 1.7 to 2.0 times, which results in the optical penetration depth decreased by 1.4 to 1.8 times. To ensure an effective procedure, the adjustment of laser parameters for the decreasing penetration depth is recommended for the re-irradiation of PDT.

[On the effect of centrifugal force upon antitumor resistance of organism]

The influence of the centrifugal force of 2 g combined with attendant factors, such as noise and electromagnetic field (in all ten exposures, 5 min each, at three- to four-day intervals), on tumor growth in C57Bl/6 mice has been studied. It was shown that the combined treatment leads to an enhancement of carcinogenesis. Increasing the centrifugal force to 3 g and the duration of exposure to 15 and 30 min increases the antitumor resistance of the organism and the life-span. It is assumed that the effect is related to the influence of the centrifugal force on metabolism and to the regularities of adaptation responses of the organism.

Cyclooxygenase-2 is a novel transcriptional target of the nuclear EGFR-STAT3 and EGFRvIII-STAT3 signaling axes

Emerging evidence indicates a novel mode of epidermal growth factor receptor (EGFR) signaling, notably, one involves EGFR nuclear translocalization and subsequent gene activation. To date, however, the significance of the nuclear EGFR pathway in glioblastoma (GBM) is unknown. Here, we report that EGFR and its constitutively activated variant EGFRvIII undergo nuclear translocalization in GBM cells, in which the former event requires EGF stimulation and the latter is constitutive. To gain insights into the effect of nuclear EGFR on gene expression in GBM, we created isogenic GBM cell lines, namely, U87MG-vector, U87MG-EGFR, and U87MG-EGFRdNLS that, respectively, express the control vector, EGFR, and nuclear entry-defective EGFR with a deletion of the nuclear localization signal (NLS). Microarray analysis shows that 19 genes, including cyclooxygenase-2 (COX-2), to be activated in U87MG-EGFR cells but not in U87MG-EGFRdNLS and U87MG-vector cells. Subsequent validation studies indicate that COX-2 gene is expressed at higher levels in cells with EGFR and EGFRvIII than those with EGFRdNLS and EGFRvIIIdNLS. Nuclear EGFR and its transcriptional cofactor signal transducer and activator of transcription 3 (STAT3) associate with the COX-2 promoter. Increased expression of EGFR/EGFRvIII and activated STAT3 leads to the synergistic activation of the COX-2 promoter. Promoter mutational analysis identified a proximal STAT3-binding site that is required for EGFR/EGFRvIII-STAT3-mediated COX-2 gene activation. In GBM tumors, an association exists between levels of COX-2, EGFR/EGFRvIII, and activated STAT3. Together, these findings indicate the existence of the nuclear EGFR/EGFRvIII signaling pathway in GBM and its functional interaction with STAT3 to activate COX-2 gene expression, thus linking EGFR-STAT3 and EGFRvIII-STAT3 signaling axes to proinflammatory COX-2 mediated pathway.

Stromal cell-derived factor-1/CXCL12 contributes to MMTV-Wnt1 tumor growth involving Gr1+CD11b+ cells

Background

Histological examinations of MMTV-Wnt1 tumors reveal drastic differences in the tumor vasculature when compared to MMTV-Her2 tumors. However, these differences have not been formally described, nor have any angiogenic factors been implicated to be involved in the Wnt1 tumors.

Methodology/Principal Findings

Here, we show that MMTV-Wnt1 tumors were more vascularized than MMTV-Her2 tumors, and this correlated with significantly higher expression of a CXC chemokine, stromal cell-derived factor-1 (SDF1/CXCL12) but not with VEGFA. Isolation of various cell types from Wnt1 tumors revealed that SDF1 was produced by both tumor myoepithelial cells and stromal cells, whereas Her2 tumors lacked myoepithelial cells and contained significantly less stroma. The growth of Wnt1 tumors, but not Her2 tumors, was inhibited by a neutralizing antibody to SDF1, but not by neutralization of VEGFA. Anti-SDF1 treatment decreased the proportion of infiltrating Gr1⁺ myeloid cells in the Wnt1 tumors, which correlated with a decrease in the percentage of endothelial cells. The involvement of Gr1⁺ cells was evident from the retardation of Wnt1 tumor growth following in vivo depletion of these cells with an anti-Gr1-specific antibody. This degree of inhibition on Wnt1 tumor growth was comparable, but not additive, to the effect observed with anti-SDF1, indicative of overlapping mechanisms of inhibition. In contrast, Her2 tumors were not affected by the depletion of Gr1⁺ cells.

Conclusions/Significance

We demonstrated that SDF1 is important for Wnt1, but not for HER2, in inducing murine mammary tumor and the role of SDF1 in tumorigenesis involves Gr1⁺ myeloid cells to facilitate growth and/or angiogenesis.

Quantitative analysis of tumor vascular structure after drug treatment

This paper reports a method that aims to quantify the changes of tumour vascular structure as a result of drug treatment. The measures we have investigated to date include: vessel radii, inter-branch lengths, tortuosity and branch angles. We show that the distribution of vessel radii is better modelled as a gamma distribution as opposed to the log-normal distribution asserted by other researchers. We propose a new metric based on multiple linear regression to measure vascular tortuosity. We report statistical analyses which confirm that (as expected), at different significance levels, all the drugs we have tested (FTI, Iressa, Nelfinavir and PI-103) have positive effects in improving a tumour's vascular network. In each case, the changes are quantified.

Blood-brain barrier breakdown and cerebellar degeneration in the course of experimental neoplastic disease. Are circulating Cytokine-Induced Neutrophil Chemoattractant-1 (CINC-1) and -2alpha(CINC-2alpha) the involved mediators?

Cerebellar degeneration belongs to indirect effects of malignancy on the nervous system. Although the involvement of immune system is accepted as a hypothesis of its pathology, the clinical observations of ineffective immunomodulatory therapy suggest complex pathomechanisms, which await elucidation. The aim of this study was to prove the blood-brain barrier integrity, its relation to cerebellar degeneration and the role of circulating Cytokine-Induced Neutrophil Chemoattractant-1 (CINC-1) and Cytokine-Induced Neutrophil Chemoattractant-2alpha (CINC-alpha) in indirect effects of experimental malignancy. Two transplantable neoplasms: breast cancer (BC) and Morris hepatoma (MH) in rats were used in the study. The blood-brain barrier breakdown was clearly proved in the course of both malignancies. We observed also morphological signs of cerebellar degeneration in both models, with linear loss of Purkinje cells and homogenization changes more pronounced in breast cancer bearing rats. We have found a significant decrease of CINC-1 concentration in serum of rats with growing MH, however BC had no effect on CINC-1 concentration. Changes in serum CINC-2alpha concentrations in BC did not reach the level of significance, however in MH bearing rats the concentrations increased three weeks after tumour transplantation. In conclusion, we may state that the development of cerebellar degeneration as an indirect effect of experimental neoplasm can result from blood-brain barrier (BBB) breakdown and possible passage of neurotoxic factors. The decreased serum concentration of CINC-1 as neuroprotective agent and increased CINC-2alpha in late stage of MH may be considered for their contribution to cerebellar degeneration.

Tumor-mediated liver X receptor-alpha activation inhibits CC chemokine receptor-7 expression on dendritic cells and dampens antitumor responses

Sterol metabolism has recently been linked to innate and adaptive immune responses through liver X receptor (LXR) signaling. Whether products of sterol metabolism interfere with antitumor responses is currently unknown. Dendritic cells (DCs) initiate immune responses, including antitumor activity after their CC chemokine receptor-7 (CCR7)-dependent migration to lymphoid organs. Here we report that human and mouse tumors produce LXR ligands that inhibit CCR7 expression on maturing DCs and, therefore, their migration to lymphoid organs. In agreement with this observation, we detected CD83(+)CCR7(-) DCs within human tumors. Mice injected with tumors expressing the LXR ligand-inactivating enzyme sulfotransferase 2B1b (SULT2B1b) successfully controlled tumor growth by regaining DC migration to tumor-draining lymph nodes and by developing overt inflammation within tumors. The control of tumor growth was also observed in chimeric mice transplanted with bone marrow from mice lacking the gene encoding LXR-alpha (Nr1h3(-/-) mice) Thus, we show a new mechanism of tumor immunoescape involving products of cholesterol metabolism. The manipulation of this pathway could restore antitumor immunity in individuals with cancer.

Host deficiency in Vav2/3 guanine nucleotide exchange factors impairs tumor growth, survival, and angiogenesis in vivo

Vav guanine nucleotide exchange factors modulate changes in cytoskeletal organization through activation of Rho, Rac, and Cdc42 small GTPases. Although Vav1 expression is restricted to the immune system, Vav2 and Vav3 are expressed in several tissues, including highly vascularized organs. Here, we provide the first evidence that Vav2 and Vav3 function within the tumor microenvironment to promote tumor growth, survival, and neovascularization. Host Vav2/3 deficiency reduced microvascular density, as well as tumor growth and/or survival, in transplanted B16 melanoma and Lewis lung carcinoma models in vivo. These defects were due in part to Vav2/3 deficiency in endothelial cells. Vav2/3-deficient endothelial cells displayed reduced migration in response to tumor cells in coculture migration assays, and failed to incorporate into tumor vessels and enhance tumor volume in tumor-endothelial cotransplantation experiments. These data suggest that Vav2/3 guanine nucleotide exchange factors play a critical role in host-mediated tumor progression and angiogenesis, particularly in tumor endothelium.

Imaging vasculature and lymphatic flow in mice using quantum dots

Quantum dots are ideal probes for fluorescent imaging of vascular and lymphatic tissues. On injection into appropriate sites, red- and near-infrared-emitting quantum dots provide excellent definition of vasculature, lymphoid organs, and lymph nodes draining both normal tissues and tumors. We detail methods for use with commercially available quantum dots and discuss common difficulties.

Minimally invasive biomarkers for therapy monitoring

Development of new drugs and optimal application of the drugs currently in use in clinical chemotherapy requires the application of biomarkers. Ideally, these biomarkers would stratify patients so that only those patients likely to respond to a particular therapy receive that therapy. However, that is not always feasible, and an alternative is to make use of early response biomarkers to determine the responding population. In this paper, a number of generic (i.e. not necessarily specific to the action mechanism of the compound) early-response biomarkers are discussed and compared in different models and with three compounds with quite different mechanisms of action: a VEGF-R inhibitor (PTK787), an mTOR inhibitor (RAD001) and a microtubule stabiliser (EPO906). The methods include noninvasive DCE-MRI and PET imaging for measuring tumour vascularity, metabolism and proliferation, as well as the minimally invasive WIN method for measuring tumour interstitial pressure (IFP). The data show that drug-induced changes in IFP (delta IFP) involve mechanism-dependent changes in the tumour vascular architecture, and that delta IFP may be considered a universal generic early-response marker of tumour response to therapy.

Biological actions of melanocyte-stimulating hormone

Melanocyte-stimulating hormone (alpha-melanotropin, MSH) may function in a number of diverse physiological roles. MSH stimulates (1) rapid translocation of melanosomes (melanin granules) in dermal melanophores to effect rapid colour change and (2) melanogenesis in normal and abnormal (melanoma) epidermal melanocytes. Both actions involve (1) initial binding of the peptide on the melanocyte membrane, (2) transduction of signal to adenylate cyclase, and (3) increased cytosolic levels of cyclic AMP. Efforts to prepare radioiodinated MSH and analogues for radioreceptor studies using melanoma membranes and intact cells reveal that conventional iodination procedures inactivate the hormone because of oxidative and iodination effects on specific structural components of the peptide. These effects can be circumvented by the use of synthetically tailored MSH analogues. Transduction of signal from receptor to adenylate cyclase requires calcium, but prostaglandin or beta-adrenoceptor stimulation of melanophores does not. The nucleotide and metal ion requirements for mouse melanoma adenylate cyclase activity have been characterized. There is both a transcriptional and translational requirement for MSH stimulation of tyrosinase activity and melanin production in melanoma cells. Melanosome translocation within melanophores is enhanced in the absence of extracellular calcium. A model for the MSH control of melanosome movements suggests a bifunctional, but compartmentalized, role for calcium in the action of MSH.

Metabolic and morphological alterations induced by proteolysis-inducing factor from Walker tumour-bearing rats in C2C12 myotubes

BACKGROUND

Patients with advanced cancer suffer from cachexia, which is characterised by a marked weight loss, and is invariably associated with the presence of tumoral and humoral factors which are mainly responsible for the depletion of fat stores and muscular tissue.

METHODS

In this work, we used cytotoxicity and enzymatic assays and morphological analysis to examine the effects of a proteolysis-inducing factor (PIF)-like molecule purified from ascitic fluid of Walker tumour-bearing rats (WF), which has been suggested to be responsible for muscle atrophy, on cultured C2C12 muscle cells.

RESULTS

WF decreased the viability of C2C12 myotubes, especially at concentrations of 20-25 mug.mL-1. There was an increase in the content of the pro-oxidant malondialdehyde, and a decrease in antioxidant enzyme activity. Myotubes protein synthesis decreased and protein degradation increased together with an enhanced in the chymotrypsin-like enzyme activity, a measure of functional proteasome activity, after treatment with WF. Morphological alterations such as cell retraction and the presence of numerous cells in suspension were observed, particularly at high WF concentrations.

CONCLUSION

These results indicate that WF has similar effects to those of proteolysis-inducing factor, but is less potent than the latter. Further studies are required to determine the precise role of WF in this experimental model.

A preliminary report on the survival of fully-hydrated living (cancer) cells to liquid helium exposure

Fully-hydrated Ehrlich carcinoma ascites cells under the protective action of DMSO fully survived exposure to near-absolute zero temperature provided by liquid helium.

Function of the Zinc-Finger Transcription FactorSNAI2in Cancer and Development

Elucidation of the molecular mechanisms that underlie disease development is still a tremendous challenge for basic science, and a prerequisite to the development of new and disease-specific targeted therapies. This review focuses on the function of SNAI2, a member of the Snail family of zinc-finger transcription factors, and discusses its possible role in disease development. SNAI2 has been implicated in diseases of melanocyte development and cancer in humans. Many malignancies arise from a rare population of cells that alone have the ability to self-renew and sustain the tumor (i.e., cancer stem cells). SNAI2 controls key aspects of stem cell function in mouse and human, suggesting that similar mechanisms control normal development and cancer stem cell properties. These insights are expected to contribute significantly to the genetics of cancer and to the development of both cancer therapy and new methods for assessing treatment efficacy.

Subclinical photodynamic therapy treatment modifies the brain microenvironment and promotes glioma growth

Photodynamic therapy (PDT) has been clinically investigated as an adjuvant local therapy for brain tumors. Therapeutic interventions intended to promote tumor cell death can also promote changes in the tumor microenvironment that could favor tumor growth. We have previously shown that PDT can activate pro-angiogenic factors in the normal rodent brain. This study seeks to further elucidate the effects of subtherapeutic doses of Photofrin-PDT on normal brain and to establish a mouse model for studying glioma progression in an environment modified by oxidative stress. Photofrin was administered to nude mice, and a defined intracranial area was illuminated with laser to deliver an optical dose equivalent to 80 J/cm(2). Three and 7 days after PDT, mice were sacrificed and brains were fixed and analyzed by immunohistochemistry. PDT treatment resulted in transient increase in cell proliferation, associated with a robust activation of astrocytes and microglia in the treated region, without causing substantial cell death. To test how this modified environment would affect glioma growth, human glioblastoma U87 cells were implanted in the PDT-treated hemisphere or in the control brain subjected to sham surgery. Significantly larger tumors were observed after 3 weeks in the PDT treated brains relative to control treatment. Our results indicate that subclinical Photofrin-PDT locally alters the brain homeostasis without inflicting significant disruption to the tissue architecture, providing a model to study the effects of the microenvironment on glioma growth, with implications for the optimization of the clinical use of PDT for brain tumors.

Chemokines as mediators of angiogenesis

Chemokines were originally described as cytokines that mediate leukocyte recruitment to sites of inflammation. Members of a subgroup of chemokines, the CXC family, also play a critical role in both physiologic and pathologic angiogenesis, including in the context of chronic inflammation, fibrosis, and malignancy. A unique feature of this family of cytokines is that, on the basis of their structure and receptor binding, individual ligands display either angiogenic or angiostatic biological activity in the regulation of angiogenesis. In this review, we summarize the key literature in this growing field.

Dietary factors and growth and metabolism in experimental tumors

Development of a diet that provides adequate nutrition and effective cancer prevention is an important goal in nutrition and cancer research. A confounding aspect of dietary control of tumor growth is the fact that some nutrients may up-regulate tumor growth, whereas other nutrients and nonnutrients down-regulate growth. Both up- and down-regulators may be present in the same foodstuff. Identification of these substances, determination of their mechanisms of action and potencies, as well as the interactions among the different mechanisms are topics of ongoing research. In this review, we describe results obtained in vivo or during perfusion in situ using solid tissue-isolated rodent tumors and human cancer xenografts in nude rats. Linoleic acid (LA), an essential n-6 polyunsaturated fatty acid (PUFA), was identified as an agent in dietary fat that is responsible for an up-regulation of tumor growth in vivo. Tumor LA uptake, mediated by high intratumor cAMP, stimulated formation of the mitogen, 13-hydroxyoctadecadienoic acid (13-HODE) and also increased ERK1/2 phosphorylation, [(3)H]thymidine incorporation and growth. A mechanism for control of this growth-promoting pathway was revealed during studies of the effects of dietary nutrients and nonnutrients known to inhibit tumor growth. These included four groups of lipophilic agents: n-3 fatty acids, melatonin, conjugated LA isomers and trans fatty acids. Each of these agents activated an inhibitory G protein-coupled receptor-mediated pathway that specifically suppressed tumor uptake of saturated, monounsaturated and n-6 PUFAs, thereby inhibiting an early step in the LA-dependent growth-promoting pathway.