Behavior of A Cell Line Derived from A Mouse Submaxillary Adenocarcinoma during the Initial 480 Days in Vitro

A cell line was established from a transplantable adenocarcinoma, containing viral particles of the A and B type, derived from a tumor appearing spontaneously in the submaxillary region of a male mouse of the C3H/He strain. This line, after 480 days in vitro, did not change the original epithelial-like morphology, the viral expression, the membrane immunofluorescence and the degree of agglutination by various plant lectins. After 208 days of culture, the presence of up to 3 pairs of metacentric chromosomes appeared in about 55% of the cells. However, this change in the chromosomal pattern was not sufficient, at least within the limits of our observation, to modify significantly the other parameters investigated, with the possible exception of the oncogenicity, which showed a modest decrease after 296 days of culture.

Fluoromodule-based reporter/probes designed for in vivo fluorescence imaging

Optical imaging of whole, living animals has proven to be a powerful tool in multiple areas of preclinical research and has allowed noninvasive monitoring of immune responses, tumor and pathogen growth, and treatment responses in longitudinal studies. However, fluorescence-based studies in animals are challenging because tissue absorbs and autofluoresces strongly in the visible light spectrum. These optical properties drive development and use of fluorescent labels that absorb and emit at longer wavelengths. Here, we present a far-red absorbing fluoromodule-based reporter/probe system and show that this system can be used for imaging in living mice. The probe we developed is a fluorogenic dye called SC1 that is dark in solution but highly fluorescent when bound to its cognate reporter, Mars1. The reporter/probe complex, or fluoromodule, produced peak emission near 730 nm. Mars1 was able to bind a variety of structurally similar probes that differ in color and membrane permeability. We demonstrated that a tool kit of multiple probes can be used to label extracellular and intracellular reporter-tagged receptor pools with 2 colors. Imaging studies may benefit from this far-red excited reporter/probe system, which features tight coupling between probe fluorescence and reporter binding and offers the option of using an expandable family of fluorogenic probes with a single reporter gene.

Correlating intravital multi-photon microscopy to 3D electron microscopy of invading tumor cells using anatomical reference points

Correlative microscopy combines the advantages of both light and electron microscopy to enable imaging of rare and transient events at high resolution. Performing correlative microscopy in complex and bulky samples such as an entire living organism is a time-consuming and error-prone task. Here, we investigate correlative methods that rely on the use of artificial and endogenous structural features of the sample as reference points for correlating intravital fluorescence microscopy and electron microscopy. To investigate tumor cell behavior in vivo with ultrastructural accuracy, a reliable approach is needed to retrieve single tumor cells imaged deep within the tissue. For this purpose, fluorescently labeled tumor cells were subcutaneously injected into a mouse ear and imaged using two-photon-excitation microscopy. Using near-infrared branding, the position of the imaged area within the sample was labeled at the skin level, allowing for its precise recollection. Following sample preparation for electron microscopy, concerted usage of the artificial branding and anatomical landmarks enables targeting and approaching the cells of interest while serial sectioning through the specimen. We describe here three procedures showing how three-dimensional (3D) mapping of structural features in the tissue can be exploited to accurately correlate between the two imaging modalities, without having to rely on the use of artificially introduced markers of the region of interest. The methods employed here facilitate the link between intravital and nanoscale imaging of invasive tumor cells, enabling correlating function to structure in the study of tumor invasion and metastasis.

Establishment of successively transplantable rabbit VX2 cancer cells that express enhanced green fluorescent protein

Morphological detection of cancer cells in the rabbit VX2 allograft transplantation model is often difficult in a certain region such as serosal cavity where reactive mesothelial cells mimic cancer cells and both cells share common markers such as cytokeratins. Therefore, tagging VX2 cells with a specific and sensitive marker that easily distinguishes them from other cells would be advantageous. Thus, we tried to establish a successively transplantable, enhanced green fluorescent protein (EGFP)-expressing VX2 model. Cancer cells obtained from a conventional VX2-bearing rabbit were cultured in vitro and transfected with an EGFP-encoding vector, and then successively transplanted in Healthy Japanese White rabbits (HJWRs) (n = 8). Besides, conventional VX2 cells were transplanted in other HJWRs (n = 8). Clinicopathological comparison analyses were performed between the two groups. The success rate of transplantation was 100% for both groups. The sensitivity and specificity of EGFP for immunohistochemical detection of VX2 cells were 84.3 and 100%, respectively. No significant differences in cancer cell morphology, tumor size (P = 0.742), Ki-67 labeling index (P = 0.878), or survival rate (P = 0.592) were observed between the two. VX2 cells can be genetically altered, visualized by EGFP, and successively transplanted without significant alteration of morphological and biological properties compared to those of the conventional model.

Effects of arsenic trioxide under different administration ways on T-cell lymphoma xenografts in nude mice: in vivo and in vitro experiments

BACKGROUND AND OBJECTIVE

In vitro, arsenic trioxide (As(2)O(3)) can inhibit proliferation of many lymphoma cell lines. In clinic, it also can be used to treat many subtypes of lymphoma. But the dosage and administration ways are undetermined yet. In this research, we studied the antitumor effect of As(2)O(3) with different administration ways on T-cell lymphoma and observed the toxicity.

METHODS

Murine T-cell lymphoma cell line EL4 was treated with As(2)O(3) of eight concentrations. Cell proliferation was detected by MTT assay. Cell apoptosis was evaluated by flow cytometry with Annexin-V-FITC/PI staining and observed under electroscope and fluorescent microscope. EL4 cells were inoculated into nude mice to establish lymphoma models. The effect of As(2)O(3) on lymphoma in nude mice was observed.

RESULTS

As(2)O(3) inhibited the proliferation of EL4 cells with a 50% inhibition concentration (IC(50)) of 1.28 micromol/L at 72 h (p < 0.05). When treated with the same total dose of As(2)O(3) by 4 mg(kg d)(-1) for seven days or 2 mg(kg d)(-1) for 14 days, the inhibition rates of tumor growth in mice were equivalent (58.8% vs. 55.6%, p = 0.351). Apoptotic cells were increased and apoptotic bodies were observed in xenograft tumor tissues. Acute liver damage is the major toxicity.

CONCLUSION

Shortening the administration course and increasing the daily dosage of As(2)O(3) can be considered as a reasonable model for treating advanced/refractory lymphomas.

Investigation of intratumoural and peritumoural lymphatics expressed by podoplanin and LYVE-1 in the hybridoma-induced tumours

Tumour-associated lymphatics contribute to a key component of metastatic spread, however, the biological interaction of tumour cells with intratumoural and peritumoural lymphatics (ITLs and PTLs) has remained unclear. To address this important issue, we have focused on the morphological and molecular aspects of newly formed lymphatics (lymphangiogenesis) and pre-existing lymphatics in the intratumoural and peritumoural tissues by using a hybridoma-induced tumour model. In the present study, ITLs with very high vessel density within the tumour mass showed small and flattened contours that varied from non-solid-to-solid tumours, whereas PTLs were relatively disorganized and tortuous, and packed with a cluster of tumour cells at the tumour periphery. Lymphatic endothelial cells (LECs) both in ITLs and PTLs were expressed with LYVE-1 and podoplanin in various tumour tissues, in which initial lymphatics were extremely extended and dilated. The tumour cells were frequently detected adhering to or penetrating lymphatic walls, especially near the open junctions. In the metastatic tissues, lymphangiogenic vasculatures occurred within the tumour matrix, and collecting PTLs represented abnormal twisty valve leaflets. The Western blot and RT-PCR analysis showed local variations of LEC proliferating potentials and lymphatic involvement in metastasis by a distinct profile of the protein and mRNA expression by LYVE-1, podoplanin, Prox-1 and vascular endothelial growth factor-3 (VEGFR-3). These findings indicated that both ITLs and PTLs, including enlarged pre-existing and newly formed lymphatics, may play a crucial role in metastasis with an active tumour cell adhesion, invasion, migration and implantation.

Recombinant adenoviruses expressing TRAIL demonstrate antitumor effects on non-small cell lung cancer (NSCLC)

INTRODUCTION

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) induces apoptosis in a variety of malignant cells, but not in normal cells. This preferential toxicity to the abnormal cells renders TRAIL potentially a very powerful therapeutic weapon against cancer. However, a requirement for large quantities of TRAIL to suppress tumor growth in vivo is one of the major factors that has hindered it from being widely applied clinically. To overcome this, we constructed a replication-deficient adenovirus that carries a human full-length TRAIL gene (Ad-TRAIL) and tested its efficacy against a lung cancer model system in comparison to that of the recombinant soluble TRAIL protein.

METHODS

To investigate the antitumor activity and therapeutic value of the Ad-TRAIL on the non-small cell lung cancer (NSCLC), four NSCLC cell lines, namely, YTMLC, GLC, A549, and H460 cells, were used. TRAIL protein expression was determined by Western blotting and flow cytometry. Cell viability was analyzed by proliferation assay, and DNA ladder and cell-cycle analysis were used to identify apoptosis. To further evaluate the effect of Ad-TRAIL in vivo, YTMLC cells were inoculated to the subcutis of nude mice. The Ad-TRAIL was subsequently administered into the established tumors. Tumor growth and the TRAIL toxicity were evaluated after treatment.

RESULTS

YTMLC cells infected with Ad-TRAIL showed decreased cell viability and a higher percentage of apoptosis. Similar, Ad-TRAIL treatment also significantly suppressed tumor growth in vivo.

CONCLUSIONS

TRAIL gene therapy provides a promising therapy for the treatment of NSCLC.

Destruction of human retinoblastoma after treatment by the E variant of encephalomyocarditis virus

The oncolytic effects of encephalomyocarditis (EMC) virus were examined in human retinoblastoma cell (Y79) cultures which were infected with 10(4 )tissue culture infectious doses (TCIDs) of the E variant of EMC (EMC-E) virus. The TCIDs were used to titer the maximum effect of EMC virus on L-929 cells. In-vitro studies showed 90% cytopathic effect (CPE) at 24 h and 100% CPE at 52 h. The CPE was used to observe pathologic effects of the cells. In-vivo studies employing human retinoblastoma grown as a tumor in nude mice, revealed degeneration of 80% of the tumor cells at 3 days and total destruction at 4 days following inoculation with the EMC-E virus. The virus is highly neurotropic in mice, but is usually not pathogenic in man. These studies suggest a possible new direction in the treatment of retinoblastoma and other malignant tumors using the viral technology.

Radiation-guided drug delivery to tumor blood vessels results in improved tumor growth delay

Tumor blood vessels are biological targets for cancer therapy. In this study, a tumor vasculature targeting system that consisted of liposomes and lectin (WGA) was built. Liposomes were used to carry a number of liposome-friendly anti-tumoral agents along with WGA, a lectin which posseses a specific affinity for binding to inflamed endothelial cells. In order to target tumor vasculature, inflammation of endothelial cells was induced by radiation. Because ionizing radiation induces an inflammatory response in tumor vasculature, lectin-conjugates were utilized to determine whether radiation can be used to target drug delivery to tumor vessels. Wheat germ agglutinin (WGA) is one such lectin that binds to inflamed microvasculature. WGA was conjugated to liposomes containing cisplatin and administered to tumor bearing mice. Tumor growth delay was used to analyze the efficacy of cytotoxicity. FITC-conjugated WGA accumulated within irradiated tumor microvasculature. WGA was conjugated to liposomes and labeled with 111In. This demonstrated radiation-inducible tumor-selective binding. WGA-liposome-conjugates were loaded with Cisplatin and administered to mice bearing irradiated tumors. Tumors treated with a combination of liposome encapsulated cisplatin together with radiation showed a significant increase in tumor growth delay as compared to radiation alone. These findings demonstrate that ionizing radiation can be used to guide drug delivery to tumor microvasculature.

Inorganic Cadmium- and Arsenite-Induced Malignant Transformation of Human Bladder Urothelial Cells

Arsenic and cadmium (Cd(+2)) are human carcinogens, and epidemiological studies have implicated both pollutants in the development of urinary bladder cancer. Despite this epidemiological base, it is unknown if either Cd(+2) or arsenite (As(+3)) can directly cause the malignant transformation of human urothelial cells. The goal of this study was to determine if Cd(+2) and/or As(+3) are able to cause the malignant transformation of human urothelial cells. The strategy employed was to expose the nontumorigenic urothelial cell line UROtsa to long-term in vitro exposure to Cd(+2) and As(+3), with the endpoint being the ability of the cells to form colonies in soft agar and tumors when heterotransplanted into nude mice. It was demonstrated that a long-term exposure to either 1 M Cd(+2) or 1 M As(+3) resulted in the selection of cells that were able to form colonies in soft agar and tumors when heterotransplanted into nude mice. The histology of the tumor heterotransplants produced by UROtsa cells malignantly transformed by Cd(+2) had epithelial features consistent with those of a classic transitional-cell carcinoma of the bladder. The histology of the tumor heterotransplants produced by cells malignantly transformed by As(+3) was unique in that the cells displayed a prominent squamoid differentiation.

[Changes of structure and function of spleen macrophages induced by malignant neoplasia]

Spleen macrophages, as most active elements of the mononuclear phagocyte system, were studied using light and electron microscopy in experimental rats and mice with differenet types of malignant neoplasia, including chemically induced carcinogenesis, transplantable tumor growth and in leukosis. In chemically induced carcinogenesis macrophage phagocytic activity was reduced, morphologically, the cellular surface smoothing, cytoplasm organell reduction and nuclear pyknotic changes were found. In animals with transplanted tumors, high activity of spleen macrophages was detected. In animals with leukosis, macrophages are characterized by reduced phagocytic activity, smoothed cellular surface and a variable number of lysosomes. The results obtained support the concept of high reactivity of the cells of mononuclear phagocyte system in neoplasia.

Experimental microcomputed tomography study of the 3D microangioarchitecture of tumors

Differences between soft X-ray imaging and microcomputed tomography (micro-CT) in the microangiographic depiction of small vessels in tumors were compared to evaluate the tumors' 3D microangioarchitecture and the progress of growth-related neovascularization. VX2 carcinomas transplanted to the auricles of 24 rabbits randomly assigned to three groups were examined after 1, 3, and 7 days. Eight rabbits without transplants were the controls. Barium sulfate was injected into the auricular artery, and conventional soft X-ray images and micro-CT microangiograms of auricle specimens were studied. Micro-CT detected vessels with diameters of less than 50 microm, and imaging from several angles clearly showed the network of tumor vessels. Moreover, micro-CT confirmed the 3D process of growth-related neovascularization. There were no significant differences between the present findings and those of our previously published microscopic study. Micro-CT should prove useful for evaluating the 3D microarchitecture of tumors and for clear imaging of tumor angiogenesis.

A novel concept of glomeruloid body formation in experimental cerebral metastases

Glomeruloid bodies (GBs), tumor-associated vascular structures with a superficial resemblance to renal glomeruli, are important histopathological features of glioblastoma multiforme, but have also been described in other types of tumors and in cerebral metastases. The purpose of this study was to elucidate the pathogenesis of these lesions in an appropriate murine model of experimental brain metastases. To do so, we injected cells from 5 different tumor lines into the internal carotid artery of mice and investigated the development, composition, and fate of GBs growing within tumor nodules. Immunohistochemical analyses and 3-dimensional reconstruction of the cerebral vasculature showed clearly that the proliferating and migrating tumor cells pull the capillaries (and the adjacent capillary branching points) into the tumor cell nest. Initially, this process lead to the appearance of simple coiled vascular structures, which later developed into chaotic and tortuous vascular aggregates with multiple narrowed afferent and efferent microvessels. Despite the absence of sprouting angiogenesis, the very low level of endothelial cell proliferation index and the ruptures of the stretched and narrowed capillary segments observed frequently between the metastatic tumor nodules, necrosis was scarce in these lesions, implying that the blood supply from the multiple afferent microvessels and from the preexistent vascular bed sufficed to provide the tumor cells with oxygen and nutrients.

In vivo mapping of fractional plasma volume (fpv) and endothelial transfer coefficient (Kps) in solid tumors using a macromolecular contrast agent: correlation with histology and ultrastructure

Contrast-enhanced MRI, immunostaining and electron microscopy were used to detect areas of intense angiogenesis in experimental tumors. This work was also aimed at evaluating the possible effect of the surrounding tissues on tumor microvasculature and at studying the penetration of macromolecules in avascular areas. Human colon carcinoma cells were implanted in subcutaneous tissue of nude mice. Dynamic T(1)-weigthed 3D pulse sequences were acquired before and after administration of Gd-DTPA-albumin to obtain parametric maps of fractional plasma volume (fpv) and transendothelial permeability (Kps). The maps suggested that tumor can be subdivided into 4 zones located in the peripheral rim (zones I-II) or in the core (zones III-IV) of the tumor itself. Significant differences (p<0.001) were found in the values of Kps and fpv of zones I-II with respect to zones III-IV. In the peripheral rim, permeability was significantly higher (p<0.01) in the muscle-peripheral region (zone I) with respect to the skin-peripheral region (zone II). In areas with high Kps, histological and ultrastructural examination revealed clusters of newly formed vessels and signs of intense permeability. Numerous vascular vesicular organs were visible in these areas. In the tumoral core, analysis of the microcirculatory parameters revealed regions with mild permeability (zone III) and regions with negligible permeability (zone IV). These 2 zones were discriminated by the average value of Kps (p<0.05), while their fpv was not significantly different. Upon histological examination, the tumoral core exhibited necrotic areas; CD31 immunocytochemistry exhibited that it was diffusely hypovascularized with large avascular areas. Upon ultrastructural examination, capillaries were rarely visible and exhibited signs of endothelial cell damage. The results suggest that segmentation based on microvascular parameters detects in vivo zones characterized by immunocytochemical and ultrastructural aspects of intense angiogenesis. The finding that a certain amount of contrast agent penetrates in the tumoral core suggests that high oncotic and hydrostatic pressure only partially hinders the penetration of macromolecules.

Monoclonally integrated HTLV type 1 in epithelial cancers from rabbits infected with an HTLV type 1 molecular clone

In addition to T cell leukemias and lymphomas, human T cell leukemia virus type 1 (HTLV-1) infection has been associated with nonhematologic malignancies and described as the cause of one case of small-cell lung carcinoma. Infected primary epithelial cells have been isolated from sweat gland and oral mucosae of HTLV-1-infected human patients. In the present study, epithelial neoplasms developed in two rabbits experimentally infected with a molecular clone of HTLV-1 (strain K30p). Serologic detection of anti-HTLV-1 and isolation of virus from blood lymphocytes at multiple time points postinjection established a course of chronic asymptomatic infection in both. One rabbit, infected for 5.5 years after intramuscular injection of HTLV-1 DNA, developed a thymoma having features of medullary differentiation. HTLV-1 provirus was detected in both thymocytes and neoplastic epithelium isolated discretely from the thymoma by laser capture microdissection. These findings provide the first experimental evidence of HTLV-1 disease after infection by HTLV-1 DNA injection. Endometrial adenocarcinoma occurred in a second rabbit 2.5 years after its inoculation with cell-associated virus. In this second case, an epithelial cell line derived ex vivo from a metastatic lesion produced virus in culture. In tumors from each of the two rabbits, the neoplastic epithelium was infected and harbored monoclonally integrated HTLV-1 provirus. Although monoclonal provirus integration alone does not establish retroviral cause of carcinogenesis unequivocally, these and other accumulating data indicate that there may be a role for HTLV-1 in diseases associated with infection of epithelia, including some epithelial cancers.

Angiomorphology of the pigmented Bomirski melanoma growing in hamster eye

An melanotic line of Bomirski Hamster Melanoma (BHM Ma) was implanted into the anterior chamber of the hamster eye and the ensuring vascular system was studied using scanning electron microscopy (SEM) of vascular corrosion casts. The tumor vasculature, induced mainly from the host iris vessels, showed generally disorganized and irregular patterns. Tortuous tumor capillaries of uneven contour with local dilatations and constrictions were drained by markedly dilated, thin-walled, venous vessels connected with the eye veins. Vascular sprouting and, less frequently, intussusceptive formation of new vessels were observed at the periphery and also within the tumor mass. The presence of numerous nodular outgrowths, varying in size, on the surface of dilated venules and venous vessels represent morphological evidence for continuous remodeling of the tumor vasculature. The observed features of the vascular system seem to provide a pathway for further tumor expansion. Our study showed that BHM Ma line, originating from an aggressive skin melanotic melanoma, implanted to the eye anterior chamber gave rise to rapidly growing tumors with the capability of inducing abundant vasculature which allows metastasis to the lungs, kidneys and regional lymph-nodes.

Cytotoxic effects of cantharidin on the growth of normal and carcinoma cells

Cantharidin is isolated from Mylabris phalerata Pallas and is a potent inhibitor of hepatocellular carcinoma cells (Hep 3B cells). In the present study, the IC(50) values of cantharidin on Hep 3B cells and normal Chang liver cells were found to be 2.2 and 30.2 microM for 36 h, respectively. Furthermore, cantharidin-treated Hep 3B cells induced cell death within 1 h (IC(50)=52.8 microM), suggesting that cantharidin is an acute cytotoxic agent. We found that although cantharidin could induce cell death, it could not directly inhibit the activity of nucleic acid biosynthesis by the cellular incorporation of 3H-thymidine, 3H-uridine or 3H-leucine. Cantharidin-treated Hep 3B cells showed no evidence of major alterations in the cell cycle distribution within 1 h. However, examination of cells after treatment for 36 h showed that cantharidin regulated the cell cycle at the G(2)/M phase. Moreover, the treated Hep 3B cells had a rounded and shrunken appearance. The microvilli of treated Hep 3B cells were reduced in number and replaced by numerous blebs. Other ultrastructural changes following cantharidin treatment included the presence of lipid droplets, swelling of the mitochondria and accumulation of glycogen particles. The findings of damaged mitochondria in the cantharidin treated Hep 3B cells in this study suggest that cantharidin can induce acute and lethal toxic effects on Hep 3B cells by inhibiting the mitochondria energy system. In conclusion, this study had demonstrated that cantharidin could inhibit progression of all phases of the Hep 3B cell cycle.

Effects of cyclic plasma perfusion on adipocyte apoptosis and lipolytic activity in VX2 carcinoma-bearing rabbits

BACKGROUND

In an animal model we found that total body fat (TBF) decreased with progression of tumors, but that it rebounded after cyclic plasma perfusion (CPP). In this study, we investigated changes in adipocyte apoptosis and serum lipolytic activity (LA) after CPP.

MATERIALS AND METHODS

TBF, LA, and adipocyte apoptotic index (AAI) in VX2 carcinoma-bearing rabbits were measured every ten days after implantation. CPP was performed every 5 days from post-implantation day (PID) 14.

RESULTS

TBF decreased as the days passed and reached 43.2 +/- 10.0% on PID 50 in the non-CPP group, while it decreased 22.7 +/- 8.8% in the CPP group. LA on PID 50 was 17.8 +/- 14.0, 33.2 +/- 6.3 mumol glycerol/10(5) adipocytes in the non-CPP group, while LA did not increase in the CPP group. AAI was 28.8 +/- 16.4, 27.8 +/- 17.7, 10.3 +/- 9.9 and 0.4 +/- 1.1 on PID 10, 20, 30, and 40, respectively, in the non-CPP group. No change was noted in AAI after CPP.

CONCLUSIONS

CPP removed a humoral factor that possesses TBF-decreasing LA, but it did not suppress adipocyte apoptosis.

Size-dependent extravasation and interstitial localization of polyethyleneglycol liposomes in solid tumor-bearing mice

We have examined the size dependence of extravasation and interstitial localization of polyethyleneglycol-coated liposomes (PEG-liposomes) in the solid tumor tissue by means of electron microscopic observation. Liposomes composed of distearoyl phosphatidylcholine, cholesterol and distearoylphosphatidylethanolamine derivative of polyethyleneglycol (PEG) were prepared in various size ranges. PEG-liposomes with an average diameter of 100-200 nm showed the most prolonged circulation time and the greatest tumor accumulation in all the solid tumors employed in this experiment. Although large PEG-liposomes with a diameter of 400 nm showed a short circulation time in normal mice, the results in splenectomized mice indicated that they do have an intrinsic prolonged circulation character in vivo. However, large PEG-liposomes could not extravasate into solid tumor tissue. These results indicate that the size of liposomes is critical for extravasation. The electron microscopic observations revealed the almost exclusive engulfment of extravasated liposomes by tumor-associated macrophages; very few were taken up by tumor cells.

Evidence for characteristic vascular patterns in solid tumours: quantitative studies using corrosion casts

The vascular architecture of four different tumour cell lines (CaX, CaNT, SaS, HEC-1B) transplanted subcutaneously in mice was examined by means of microvascular corrosion casting in order to determine whether there is a characteristic vascular pattern for different tumour types and whether it differs significantly from two normal tissues, muscle and gut. Three-dimensional reconstructed scanning electron microscope images were used for quantitative measurements. Vessel diameters, intervessel and interbranch distances showed large differences between tumour types, whereas the branching angles were similar. In all tumours, the variability of the vessel diameters was significantly higher than in normal tissue. The quantitative data provide strong evidence for a characteristic vascular network determined by the tumour cells themselves.

Morphological, histochemical, immunohistochemical, and ultrastructural characterization of tumors and dysplastic and non-neoplastic lesions arising in BK virus/tat transgenic mice

To study the role in AIDS pathogenesis of the human immunodeficiency virus type 1 (HIV-1) Tat protein, a transactivator of viral and cellular genes, we generated transgenic mice with a recombinant DNA containing BK virus (BKV) early region and the HIV-1 tat gene, directed by its own promoter-enhancer. DNA hybridization revealed that the transgene is stably maintained in all organs of transgenic mice as a tandem insertion in a number of copies ranging from 5 to 20 per cell. In addition, tat and BKV RNA were expressed in all tissues. Transgenic mice developed three types of lesions: 1) tumors, 2) hyperplastic and dysplastic lesions, and 3) non-neoplastic lesions. Tumors of different histotypes, such as lymphomas, adenocarcinomas of skin glands, leiomyosarcomas, skin squamous cell carcinomas, hepatomas, hepatocarcinomas, and cavernous liver hemangiomas, developed in 29% of transgenic animals. The majority of tumors were malignant, invasive, and producing metastases. Conversely, tumors of only two histotypes (lymphomas and adenocarcinomas of skin glands) appeared in control mice. Hyperplastic and dysplastic lesions were more frequent in transgenic than in control mice and involved the skin or its adnexes, the liver and the rectum, indicating multiple targets for the activity of the transgene. Pyelonephritis, frequently complicated with hydronephrosis, inflammatory eye lesions, and amyloid depositions represented the most frequent non-neoplastic lesions detected in transgenic mice. Many of the pathological findings observed in this animal model are comparable to similar lesions appearing in AIDS patients, suggesting a relevant role for Tat in the pathogenesis of such lesions during the course of AIDS.

Regulation of transport pathways in tumor vessels: role of tumor type and microenvironment

Novel anti-neoplastic agents such as gene targeting vectors and encapsulated carriers are quite large (approximately 100-300 nm in diameter). An understanding of the functional size and physiological regulation of transvascular pathways is necessary to optimize delivery of these agents. Here we analyze the functional limits of transvascular transport and its modulation by the microenvironment. One human and five murine tumors including mammary and colorectal carcinomas, hepatoma, glioma, and sarcoma were implanted in the dorsal skin-fold chamber or cranial window, and the pore cutoff size, a functional measure of transvascular gap size, was determined. The microenvironment was modulated: (i) spatially, by growing tumors in subcutaneous or cranial locations and (ii) temporally, by inducing vascular regression in hormone-dependent tumors. Tumors grown subcutaneously exhibited a characteristic pore cutoff size ranging from 200 nm to 1.2 microm. This pore cutoff size was reduced in tumors grown in the cranium or in regressing tumors after hormone withdrawal. Vessels induced in basic fibroblast growth factor-containing gels had a pore cutoff size of 200 nm. Albumin permeability was independent of pore cutoff size. These results have three major implications for the delivery of therapeutic agents: (i) delivery may be less efficient in cranial tumors than in subcutaneous tumors, (ii) delivery may be reduced during tumor regression induced by hormonal ablation, and (iii) permeability to a molecule is independent of pore cutoff size as long as the diameter of the molecule is much less than the pore diameter.

Ultrastructure of murine tumour cell lines defective in MHC class I expression before and after interferon-gamma treatment

Two tumour cell clones, 6D1 and 4C2 cells, which are defective both in the major histocompatibility gene complex (MHC) class I expression and in the endogenous antigen presentation, are recovered with interferon (IFN)-gamma treatment. The present study describes the ultrastructure of these cells by using scanning and transmission electron microscopy in relation to the effect of IFN-gamma treatment. The general morphology of these cells was found to be similar to each other and comparable to that of a tumour cell clone, 4A1 cells, of the same origin, normal in MHC class I expression; they exhibited a fibroblast-like appearance and had many blebs on all the cell surfaces, with desmosome-like junctions between cells. On IFN-gamma treatment, surface fine blebs appeared less, and mitochondria became more densely stained. Expression of MHC class I molecules on the cell surface was much higher in the IFN-gamma treated 6D1 and 4C2 cells than in untreated cells, when estimated by immunoelectron microscopy. The addition of an epitope peptide to these cells did not enhance the class I expression, which differed from other antigen presentation-defective cells such as RMA-S cells, nor change the cell surface morphology.

Desmosomes and disease

Considerable progress has been made in our knowledge of desmosomes and their components. Molecular cloning of the desmosomal glycoproteins has established that desmoglein 1 and desmoglein 3 are targets for autoantibodies in the blistering diseases pemphigus foliaceus and pemphigus vulgaris respectively. New evidence suggests that another desmosomal glycoprotein, desmocollin 1, is the major target antigen in the upper epidermal form of intercellular IgA dermatosis (IgA pemphigus). In human cancer there is accumulating evidence which suggests a role for desmosomes in the prevention of invasion and metastasis. The possibility exists that a mutation in a desmosomal glycoprotein gene is responsible for an inheritable human disease, the striated form of palmoplantar keratoderma.

Improved biodistribution of 125I-labeled anti-Tac disulfide-stabilized Fv fragment by blocking its binding to the alpha subunit of the interleukin 2 receptor in the circulation with preinjected humanized anti-Tac IgG

Animal studies using radiolabeled anti-Tac disulfide-stabilized Fv (dsFv) monoclonal antibody have shown formation of complexes in serum with the soluble alpha subunit of the interleukin 2 receptor alpha (sIL-2R alpha). In this study, we improved the targeting of 125I-labeled anti-Tac dsFv to receptor-positive tumors in the presence of circulating receptor by preinjecting unlabeled humanized anti-Tac IgG antibody (HuTac IgG). We used mice bearing SP2/Tac tumor xenografts that express the IL-2R alpha. A positive correlation was seen between tumor size and the concentration of circulating receptor. Tumor-bearing mice were injected with 125I-labeled anti-Tac dsFv (400 ng), either alone or 15 min after injection of HuTac IgG. The 125I-labeled anti-Tac dsFv formed high molecular weight complexes with the sIL-2R alpha. The fraction of the dsFv present in the complexes increased as tumor size increased (greater sIL-2R alpha levels). The fractions of dsFv in the complexes were 9.9- to 11.6-fold higher when sIL-2R alpha was not blocked with preinjected HuTac IgG. The administration of a 12-fold molar excess of HuTac IgG over sIL-2R alpha resulted in >80% of the 125I activity present as the dsFv rather than in the complexes. Furthermore, the biodistribution of 125I-labeled anti-Tac dsFv was improved by blocking its binding to sIL-2R alpha by preinjecting HuTac IgG. Specifically, in the preinjected group, at 15 min postinjection, the 125I-labeled anti-Tac dsFv levels in tumor increased to 10.8% compared to 5.6% injected dose per gram in the non-preinjected group. In summary, our studies showed that preinjection of HuTac IgG can block the formation of complexes of circulating sIL-2R alpha and 125I-labeled anti-Tac dsFv. This blockade is associated with faster blood clearance, higher tumor uptake, and greater tumor:nontumor ratios of the radiolabeled antibody fragment.

Correlation of subcellular and intratumoral photosensitizer localization with ultrastructural features after photodynamic therapy

Photodynamic therapy (PDT) of cancer typically involves systemic administration of tumor-localizing photosensitizers followed 48-72 h later by exposure to light of appropriate wavelengths. Knowledge about the distribution of photosensitizers in tissues is still fragmentary. In particular, little is known as to the detailed localization patterns of photosensitizers in neoplastic and normal tissues as well as the relationship between such patterns and the actual targets for the photosensitizing effect. This review focuses on ultrastructural features seen in treated cells and tumors. An attempt is made to correlate these findings with the subcellular/intratumoral localization pattern of the photosensitizers in tumor cell lines in vitro and in tumor models in vivo. Several subcellular sites are main targets of PDT with different sulfonated aluminum phthalocyanines (AIPcSn) in the human tumor cell line LOX. Nuclei are not among the primary targets. Overall, the ultrastructural changes correlate well with the data about the subcellular localization patterns for each analogue of AIPcSn in the same cell line. Similar findings are also obtained for the family of sulfonated mesotetraphenylporphines (TPPSn) in the NHIK 3025 cell line. The mechanisms involved in the killing of tumors by PDT seem to be a complex interplay between direct and indirect (via vascular damage) effects on neoplastic cells according to the intratumoral localization pattern of the applied dye. Several factors can affect the localization pattern of a drug, such as its chemical character, the mode of drug delivery, the time interval between drug administration and light exposure, and tumor type. Furthermore, whether local immune reactions (such as macrophages) and apoptosis (programmed cell death) are involved in the destruction of neoplastic cells by PDT in vivo is still an enigma. A general model for PDT-induced tumor destruction is suggested.

The architectural organization of nuclear metabolism

Nucleic acid metabolism is structurally organized in the nucleus. DNA replication and transcription have been localized to particular nuclear domains. Additional domains have been identified by their morphology or by their composition; for example, by their high concentration of factors involved in RNA splicing. The domain organization of the nucleus is maintained by the nuclear matrix, a nonchromatin nuclear scaffolding that holds most nuclear RNA and organizes chromatin into loops. The nuclear matrix is built on a network of highly branched core filaments that have an average diameter of 10 nm. Many of the intermediates and the regulatory and catalytic factors of nucleic acid metabolism are retained in nuclear matrix preparations, suggesting that nucleic acid synthesis and processing are structure-bound processes in cells. Tissue-specific and malignancy-induced variations in nuclear structure and metabolism may result from altered matrix architecture and composition.

Morphological studies of effector cell-microvessel interactions in adoptive immunotherapy in tumor-bearing animals

Murine lymphokine-activated natural killer (A-NK) cells are able to migrate to and accumulate in tumor metastases. However, the exact migratory pattern is as yet unknown. In the present study, we have investigated the migration from the vasculature towards malignant tissues of various effector cells. Our results indicate that murine A-NK cells seem to be arrested for an extended period of time in the microvasculature and also, although infrequently, to adhere to the endothelial lining of larger vessels close to tumor tissues before extravasation. While murine T lymphokine-activated killer and rat A-NK cells accumulate significantly in the subendothelial areas of larger venules in normal tissues, no such accumulation is observed with respect to murine A-NK cells. Electron microscopy reveals that the murine A-NK cells undergo an extreme deformation during extravasation and tumor infiltration. Furthermore, the cells are shown to be in an activated stage probably facilitating their migration, and hence, the elimination of tumor cells.

A new allogeneic model for metastatic melanoma

Metastatic melanoma cells, clonally derived from an affected lymph node of an ultraviolet-irradiated laboratory opossum, were allografted subcutaneously into suckling young, juveniles and adults to determine their tumorigenicity and metastatic potential. All injected 1- and 3-week-old suckling young survived well beyond weaning at 8 weeks. One died 12 weeks after injection from the effects of rampant metastatic involvement, while the rest were killed 13 to 26 weeks after injection. At necropsy, most animals showed extensive primary tumour growth, many showed metastasis to nodes and/or lungs, and in some there was dissemination to distant sites including liver and spleen. Animals injected as juveniles or adults rejected the allografts. Injection of allogeneic malignant melanoma cells during early postnatal development facilitates successful, long-term allografting and metastasis without concomitant immunosuppressive agents. Developmental lack of self-recognition (immunological immaturity) or induced tolerance may be responsible. This unique model system will be useful for further metastasis studies and may be valuable for investigations of novel antineoplastic therapies.

Dynamic scaling in the dielectric response of excised EMT-6 tumours undergoing hyperthermia

A constant-phase-angle response (CPA) has been identified in the dielectric spectrum of EMT-6 tissues undergoing hyperthermia. A dynamic scaling relationship between the static permittivity and conductivity using the CPA frequency exponent n has been shown to occur during the destructive phase of hyperthermia. This behaviour has been attributed to the self-similar structure of the internal membrane compartments of the cells and described by means of a hierarchical circuit model. In this way the CPA exponent has been related to the convolution of internal membrane surfaces lying in between the mitochondria and the outer cell wall. The dynamic scaling is assigned to the progressive destruction of cell membranes in sequence from the outside inwards.

Suppression and promotion of tumor growth by monoclonal antibodies to ErbB-2 differentially correlate with cellular uptake

Amplification and overexpression of the erbB-2/neu protooncogene are frequently associated with aggressive clinical course of certain human adenocarcinomas, and therefore the encoded surface glycoprotein is considered a candidate target for immunotherapy. We previously generated a series of anti-ErbB-2 monoclonal antibodies (mAbs) that either accelerate or inhibit the tumorigenic growth of erbB-2-transformed murine fibroblasts. The present study extended this observation to a human tumor cell line grown as xenografts in athymic mice and addressed the biochemical differences between the two classes of mAbs. We show that the inhibitory effect is dominant in an antibody mixture, and it depends on antibody bivalency. By using radiolabeled mAbs we found that all of three tumor-inhibitory mAbs became rapidly inaccessible to acid treatment when incubated with tumor cells. However, a tumor-stimulatory mAb remained accessible to extracellular treatments, indicating that it did not undergo endocytosis. In addition, intracellular fragments of the inhibitory mAbs, but not of the stimulatory mAb, were observed. Electron microscopy of colloidal gold-antibody conjugates confirmed the absence of endocytosis of the stimulatory mAb but detected endocytic vesicles containing an inhibitory mAb. We conclude that acceleration of cell growth by ErbB-2 correlates with cell surface localization, whereas inhibition of tumor growth is associated with an intrinsic ability of anti-ErbB-2 mAbs to induce endocytosis. These conclusions are relevant to the selection of optimal mAbs for immunotherapy and may have implications for the mechanism of cellular transformation by an overexpressed erbB-2 gene.

Correlation between the light scattering and the mitochondrial content of normal tissues and transplantable rodent tumors

The development of noninvasive optical studies necessitates an understanding of the biological parameters which affect light propagation in soft tissues. In the present report, we have measured the optical properties of various normal (i.e., perfused liver, brain, skeletal muscle, white adipose tissue) and neoplastic rodent tissues (i.e., glioma, hepatoma, mammary adenocarcinoma) by using time-resolved spectroscopy. The contribution of the hemoglobin (+ myoglobin in the case of muscle) to the total light absorption at 780 nm has been determined. This contribution varies from about 25% (brain, skeletal muscle) to about 100% (white adipose tissue, 13762A mammary adenocarcinoma, 9L glioma). These results are explained by different blood volume fractions in the tissues and by the existence at 780 nm of other chromophores, such as the mitochondrial cytochrome oxidase. Secondly, the dependence of the light scattering of the tissue on both the cell and the mitochondrial content has been analyzed. The results indicate that there is no correlation between the light scattering and the DNA content, measured as an indicator of the cell number in the tissue. The scattering coefficient is proportional to both the succinate dehydrogenase activity and the mitochondrial protein content of the tissue, which are indicators of the mitochondria content of the tissue when based upon estimates of tissue wet weight.

Immunohistochemical findings on androgen receptor in mouse androgen-dependent tumor (Shionogi Carcinoma 115) and its independent sublines

To examine the androgen receptor in androgen-dependent and -independent tumor immunohistochemically, an indirect immunofluorescence study with an antibody to human androgen receptor was performed. Shionogi Carcinoma 115 (SC 115) cells are an androgen-dependent mouse tumor, but the growth is sustained without androgen when fetal bovine serum is added to serum-free medium. Cells obtained from successive culture (A (-)X cells; X is generations after removal of androgen) were androgen-independent but showed binding to androgen. SC 115 cells, A (-) cells and CS 2 cells which are the other androgen-independent cells derived from SC 115, were used in the study. The androgen receptor (AR) in SC115 cells was stained as small-sized oval granules localized in the nucleus, and the number of the granules was 10-20 per cell. Removal of testosterone for one day as well as one week did not change the size of the AR, but some of the AR in A (-) 10 cells and in generations thereafter appeared to be large. Other small ones were similar to that in SC 115 cells. The nuclear location of the AR did not change in A (-) cells. The ratio of cells containing large AR to the total number of cells increased with each generation after the removal of testosterone from the culture. The addition of testosterone to the culture changed the AR in A (-) 40 cells to small ones, but did not influence the form of the AR in A (-) 60 cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Strategy for boron neutron capture therapy against tumor cells with over-expression of the epidermal growth factor-receptor

PURPOSE

Gliomas, squamous carcinomas and different adenocarcinomas from breast, colon and prostate might have an increased number of epidermal growth factor (EGF) receptors. The receptors are, in these cases, candidates for binding of receptor specific toxic conjugates that might inactivate cellular proliferation. The purpose of this study was to evaluate whether it is reasonable to try ligand-dextran based conjugates for therapy.

METHODS AND MATERIALS

EGF or TGF alpha were conjugated to dextran and binding, internalization, retention and degradation of eight types of such conjugates were analyzed in EGF-receptor amplified glioma cells. The conjugates were labelled with radioactive nuclides to allow detection and two of the conjugates were carrying boron in the form of carboranyl amino acids or aminoalkyl-carboranes. Comparative binding tests, applying 125I-EGF, were made with cultured breast, colon and prostate adenocarcinoma, glioma and squamous carcinoma cells. Some introductory tests to label with 76Br for positron emission tomography and with 131I for radionuclide therapy were also made.

RESULTS

The dextran part of the conjugates did not prevent receptor specific binding. The amount of receptor specific binding varied between the different types of conjugates and between the tested cell types. The dextran part improved intracellular retention and radioactive nuclides were retained for at least 20-24 h. The therapeutical effect improved when 131I was attached to EGF-dextran instead of native EGF.

CONCLUSION

The improved cellular retention of the ligand-dextran conjugates is an important property since it gives extended exposure time when radionuclides are applied and flexibility in the choice of time for application of neutrons in boron neutron capture therapy (BNCT). It is possible that ligand-dextran mediated BNCT might allow, if the applied neutron fields covers rather wide areas around the primary tumor, locally spread cells that otherwise would escape treatment to be inactivated.

Active and passive mechanisms of [fluorine-18] fluorodeoxyglucose uptake by proliferating and prenecrotic cancer cells in vivo: a microautoradiographic study

In this study, [18F]FDG uptake mechanisms were investigated in neoplastic cells during cell proliferation and cell death.

METHODS

Detailed analysis was performed on mouse tumor models of different growth rates using [18F]FDG, [6-13H]thymidine [3H]Thd (a precursor of DNA synthesis) and [125I]bovine serum albumin ([125I]BSA) (a marker of diffusion) with autoradiographic and histopathologic techniques and electron microscopy.

RESULTS

The three compounds, [18F]FDG, [3H]Thd and [125I]BSA, showed different heterogeneous patterns of distribution within tumor tissue sections in neoplastic and non-neoplastic cellular elements. The uptake of [18F]FDG by prenecrotic (or necrobiotic) tumor cells surrounding focal necrotic cell debris was 1.5 to 2.3 times higher than that of viable tumor cells. Prenecrotic cells did not retain trapped [18F]FDG; therefore, the uptake was considered to be nonmetabolic. Inconspicuous cell membrane, vesicular cytoplasmic organelles and condensed nuclear chromatin were remarkable findings in the prenecrotic cells. A comparison of viable tumor cells in tumors undergoing different growth rates showed that the ratio of [18F]FDG uptake was similar to that of [3H]Thd uptake in each S-phase cell. Fluorine-18-FDG showed a cell cycle dependency, with a higher uptake observed in cells in G0/G1 and G2 phases of the cell cycle compared with the S and M phases.

CONCLUSION

A passive mechanism of [18F]FDG uptake may exist in the necrobiotic/prenecrotic or hypoxic/anoxic cells in tumors. However, the discordance of [18F]FDG and [3H]Thd uptake may be the result of the different cell cycle dependency of tracer uptake in the same tumor.

Intermediate filaments in rat pancreatic acinar tumors, human ductal carcinomas, and other gastrointestinal malignancies

BACKGROUND/AIMS

Keratin is a member of the intermediate filament family in epithelial cells. Two-dimensional gel electrophoresis of different epithelial cells has shown 20 different keratin polypeptides. Therefore, mapping of the keratin polypeptides can be used to define a specific tissue.

METHODS

Cytokeratin expression was investigated by using monoclonal antibodies in human surgical specimens and autopsy material of pancreatic, gastric, liver, and colon carcinomas and cholangiocarcinomas, and their metastasis to lymph nodes and liver was examined. In addition, rat acinar cell carcinomas were used to compare cytokeratin expression in ductal vs. acinar cell pancreatic carcinomas.

RESULTS

Human pancreatic ductal carcinomas expressed keratins 7, 8, 18, and 19, whereas the majority of rat acinar carcinomas did not express keratins typical for ducts in rat pancreas. The keratin patterns of gastric and colon carcinomas were identical with keratins 8, 18, and 19. In contrast, hepatocellular carcinomas expressed the same keratin pattern as pancreatic acinar carcinomas with keratins 8 and 18, whereas cholangiocarcinomas expressed keratin 7, 8, 18, and 19, similar to pancreatic ductal carcinomas. Metastasis of pancreatic ductal and colon carcinomas retained their keratin patterns.

CONCLUSIONS

Keratin polypeptide typing of unknown malignant cells can be a useful tool for cell identification.

Cross-competition between vasoactive intestinal peptide and somatostatin for binding to tumor cell membrane receptors

Vasoactive intestinal peptide (VIP) is a 28-amino acid peptide with a wide range of biological activities. Recent data suggest that functional VIP receptors are expressed on various tumor cells. Somatostatin (SST) and its long-acting analogue octreotide (OCT) are potent inhibitors of tumor cell growth and secretion. In the present study, the interactions between VIP and SST/OCT on primary tumors (insulinomas, n = 3; VIPomas, n = 2; intestinal adenocarcinomas, n = 5; neuroblastomas, n = 5; papillary thyroid cancers, n = 7; carcinoids, n = 5; ductal breast cancers, n = 8; small cell lung cancers, n = 3; ACTH-producing hypophyseal adenomas, n = 5; pheochromocytomas, n = 5) as well as on tumor cell lines (A431, HT29, PANC1, COLO320, HMC1, and KU812 cells) were analyzed by use of 123I-labeled VIP and 123I-labeled Tyr-3-OCT. Cross-competition between VIP and SST/OCT for binding to tumor cells was observed. The rank-order of potency for displacement of 123I-labeled VIP binding to intact A431 cells was VIP [concentration causing half-maximal inhibition (IC50) = 2.9 +/- 1.9 (SD) nM] > OCT (IC50 = 9.3 +/- 1.7 nM) = SST > substance P = secretin (IC50 = 1 microM). Binding of 123I-labeled Tyr-3-OCT to A431 cells, in turn, was inhibited by OCT = Tyr-3-OCT (IC50 = 1.5 +/- 0.3 nM) = SST > VIP (IC50 = 4.9 +/- 1.1 nM). This rank-order of potency was also obtained for primary tumors and tumor cell lines. Furthermore, SST and OCT inhibited VIP-induced [3H]thymidine incorporation, cyclic AMP formation, and tyrosine kinase activity with IC50 values < 10 nM. Together, these data provide evidence for functional interactions between SST and VIP on various tumor cells. These interactions may involve peptide cross-competition at cellular binding sites and may have implications for the biology and pathophysiology of respective cells and disease states.

Extensive deposition of basement membrane by tumours: a prognostic factor? A reappraisal

A loss of the continuous linear deposit of basement membrane around invasive carcinomas has been suggested to correlate with their increased invasiveness. In contrast, extensive basement membrane deposition would represent a more favourable prognosis. The Engelbreth-Holm-Swarm (EHS) tumour, a transplantable neoplasm, is widely used for its ability to synthesize and deposit large amounts of basement membrane components. We have evaluated the metastatic potential of this neoplasm 2 months after subcutaneous inoculation. Histological examination of lung sections revealed the presence of numerous metastatic foci. The metastatic cells retained their organization into clusters surrounded by extracellular matrix. Both the 72 kDa and the 92 kDa type IV collagenases were detected by zymography in Triton or urea extract (matrigel) of primary tumour. These results cast doubt on the hypothesis that the extensiveness of basement membrane deposition might always be of prognostic value by being inversely correlated with the degree of invasiveness of a carcinoma.

Internal dosimetry using data derived from autoradiographs

Cancer therapies based on administered radionuclides require accurate information on tumor dose. One of the major factors influencing the distribution of absorbed-dose characteristics is the uniformity of the radiolabel distribution in tissue. To study the effect of nonuniformities, we used image analysis techniques to measure automatically the coordinates of autoradiographic grains (sources) and cell nuclei in cut sections from three different tumors, following treatment with radiolabeled antibodies. The spatial distribution data of sources and cell nuclei from these tumor sections were assessed and the pattern of energy deposition in the cell nuclei calculated, assuming that each autoradiograph grain corresponded to a source of the alpha emitter astatine-211 (211At) or the beta emitter yttrium-90 (90Y). The distribution of deposited energy obtained for the real grain distributions was compared to the distribution assuming a locally uniform source distribution, i.e., simulating grain count averaging as produced by a microdensitometric method within a 100 x 100 microns 2 frame size (frame averaging), and a uniform distribution across the entire section (section averaging). The results show first that when the grain distribution is uniform, the average dose within the section is an adequate estimate of the dose to the cell nuclei. Second, when the grain distribution is nonuniform, the distribution of doses to the cell nuclei is significantly less when calculations use the measured grain coordinates, or frame averaging, than when section averaging is used. Third, when the sources are located on or in the cells, both frame and section averaging produce underestimates of the dose to the cell nuclei.

Expression of tie receptor tyrosine kinase in leukemia cell lines

The tie receptor tyrosine kinase mRNA was originally identified as an amplified product in reverse transcription-polymerase chain reaction analysis of human K562 leukemia cell RNA. In situ hybridization analysis revealed that the corresponding mouse gene is expressed predominantly in endothelial cells. We have explored tie mRNA and protein expression in tumor cell lines. The 4.4 kb tie mRNA was expressed at high levels in five of five human megakaryoblastic leukemia cell lines studied and in two IL-3-dependent mouse myeloid leukemia cell lines, but not in 42 other leukemia cell lines representing various hematopoietic lineages. Increased expression of tie mRNA and protein was observed upon treatment of the megakaryoblastic leukemia cells with the tumor promoter 12-0-tetradecanoyl-phorbol-13-acetate (TPA), known to enhance megakaryoblastic markers. Among several cell lines from solid tumors, two fibrosarcomas, one rhabdomyosarcoma and one melanoma cell line were positive for tie mRNA. These results suggest that among hematopoietic lineages tie is predominantly expressed in cells with megakaryoblastic properties and that the tie tyrosine kinase is a receptor for a regulatory factor specific for megakaryoblasts, endothelial cells, and occasional tumor cell lines derived from mesenchymal tissues.

Loss of the basement membrane matrix molecule, bamin, in diphenylamine-treated mice

Polycystic kidney disease (PKD) is a life-threatening disease characterized by focal dilatations or cysts in certain kidney tubules. Changes (i.e. thickening) in the support structure for these tubules, the basement membrane, have been related to the development of the cysts. Analysis of changes in basement membranes of humans with PKD is difficult, however, due to the restricted amount of material available for study. Several genetic and induced animal models, including diphenylamine-treated rats, have been employed to study the effects of PKD on basement membrane synthesis. While all these studies agree that PKD has a significant influence on basement membranes, no clear understanding as to how PKD effects basement membrane composition has emerged. Here, we report our findings of the effect of diphenylamine treatment on the composition of the basement membrane. Our immunohistological studies indicate that bamin, a recently described glycoprotein associated with glomerular basement membranes (Robinson et al., 1989), is not present in the glomerular basement membranes of diphenylamine-treated mice. This finding was confirmed by analysis of the composition of the basement membrane matrix synthesized by EHS tumors grown in control and diphenylamine-treated mice. The possible role of bamin in the pathogenesis of renal cysts is discussed.

Membrane and cytoskeleton are intracellular targets of rhein in A431 cells

The antineoplastic drug rhein (4,5-dihydroxyanthraquinone-2-carboxylic acid) has been hypothesized to interfere with tumor cell proliferation by affecting energy metabolism and mitochondrial function. In this study, the intracellular targets of rhein were investigated in the A431 epithelial cell line by means of biophysical and structural techniques. After treatment with 50 microM rhein at different times (8 and 24 hours), a series of remarkable morphological modifications ultimately leading to irreversible cell injury was observed. In particular, scanning and transmission electron microscopic observations point to the cell surface and mitochondria as probable targets of this drug. In addition, biophysical analyses conducted by electron paramagnetic resonance (EPR) spectroscopy seem also to indicate that cellular membranes are a direct target in rhein-induced damage. Concomitantly the cytoskeletal network underlying the inner leaflet of the plasma membrane (the microfilament system) also underwent a rearrangement. Taken together, the effects induced by rhein presented here seem to indicate that this drug, as well as other anthraquinones or other compounds that selectively impair energy metabolism, can act on neoplastic cells by probably altering cell membrane function and membrane-associated cytoskeleton.

Expression of vascular endothelial growth factor does not promote transformation but confers a growth advantage in vivo to Chinese hamster ovary cells

Vascular endothelial growth factor (VEGF) is a mitogen with a specificity for endothelial cells in vitro and an angiogenic inducer in vivo. We tested the hypothesis that VEGF may confer on expressing cells a growth advantage in vivo. Dihydrofolatereductase--Chinese hamster ovary cells were transfected with expression vectors which direct the constitutive synthesis of VEGF. Neither the expression nor the exogenous administration of VEGF stimulated anchorage-dependent or anchorage-independent growth of Chinese hamster ovary cells in vitro. However, VEGF-expressing clones, unlike control cells, demonstrated an ability to proliferate in nude mice. Histologic examination revealed that the proliferative lesions were compact, well vascularized, and nonedematous. Ultrastructural analysis revealed that capillaries within the lesions were of the continuous type. These findings indicate that the expression of VEGF may confer on cells the ability to grow in vivo in the absence of transformation by purely paracrine mechanisms. Since VEGF is a widely distributed protein, this property may have relevance for a variety of physiological and pathological proliferative processes.