Antigenic differences between a primary hamster lymphosarcoma and its liver metastases

An antiserum was raised in rabbits against a primary metastasizing lymphosarcoma (ML) of the hamster. This was made tumor-specific by absorption with normal hamster tissue extracts. Immunoglobulin-G was prepared and tested for its cytotoxicity towards cells derived from the primary tumor and its liver metastases. The ML-specific IgG was found to be 2--5 times more cytotoxic for cells derived from the primary tumor compared to cells obtained from liver metastases.     

Different biological behavior of AKR lymphoma cells from primary and metastatic tumors

AKR lymphoma cells derived from primary s.c. tumors (PT) and cells from their metastases (MT) were inoculated into recipient mice in order to compare their malignant behavior. A higher malignant potential of MT compared to PT cells was found. The results support the hypothesis that metastasis is a process of selection of cells possessing a potential to metastasize, which preexist in the primary tumor. In the model used, both the selection of 'variants' of malignancy and the assay of malignancy were as close as possible to natural tumor progression.     

Different biological behavior of AKR lymphoma cells from primary and metastatic tumors

Summary AKR lymphoma cells derived from primary s.c. tumors (PT) and cells from their metastases (MT) were inoculated into recipient mice in order to compare their malignant behavior. A higher malignant potential of MT compared to PT cells was found. The results support the hypothesis that metastasis is a process of selection of cells possessing a potential to metastasize, which preexist in the primary tumor. In the model used, both the selection of variants of malignancy and the assay of malignancy were as close as possible to natural tumor progression.The authors are thankful to Mrs Ora Gal-Mor and Mrs Elinora Miron for skillful technical assistance.     

Prevention of experimental liver metastases by D-galactose

The metastasis of malignant tumors from a primary site to near and distant secondary sites is probably the most important event in the pathogenesis of cancer and it accounts for most cancer deaths. Whereas advances in the treatment of primary cancer have led to increased patient survival, metastatic cancers are still the most difficult group of diseases to treat successfully. As organ-characteristic lectins play an important role in the organ manifestation of metastatic islets, it might be possible (e.g. during surgical operations on malignant tumors) to block those organ-characteristic lectins with the appropriate receptor-bearing glycoconjugates in order to inhibit the metastatic spread. Recent experiments have demonstrated that neuraminidase treatment of tumor cells (mouse sarcoma-1) alters in vivo (Balb/c-mice) the organotropic distribution of metastases; instead of being found exclusively in the lung, they are found both in lung and liver. However, pre-injection and regular application of D-galactose--the same holds for arabinogalactan--prevents the setting of metastases in the liver but does not influence the metastatic process to the lung, whereas mannan--as a galactose-free control substance--does not alter the initial pattern of metastasis to lung and liver.     

Prevention of experimental liver metastases by D-galactose

Summary The metastasis of malignant tumors from a primary site to near and distant secondary sites is probably the most important event in the pathogenesis of cancer and it accounts for most cancer deaths¹. Whereas advances in the treatment of primary cancer have led to increased patient survival, metastatic cancers are still the most difficult group of diseases to treat successfully². As organ-characteristic lectins play an important role in the organ manifestation of metastatic islets^3,4, it might be possible (e.g. during surgical operations on malignant tumors) to block those organ-characteristic lectins with the appropriate receptor-bearing glycoconjugates in order to inhibit the metastatic spread. Recent experiments have demonstrated that neuraminidase treatment of tumor cells (mouse sarcoma-1) alters in vivo (Balb/c-mice) the organotropic distribution of metastases; instead of being found exclusively in the lung, they are found both in lung and liver. However, pre-injection and regular application of D-galactose — the same holds for arabinogalactan^5,6,13 — prevents the settling of metastases in the liver but does not influence the metastatic process to the lung, whereas mannan — as a galactose-free control substance — does not alter the initial pattern of metastasis to lung and liver.     

Metastasis: cell-autonomous mechanisms versus contributions by the tumor microenvironment

The fatality of cancer predominantly results from the dissemination of primary tumor cells to distant sites and the subsequent formation of metastases. During tumor progression, some of the primary tumor cells as well as the tumor microenvironment undergo characteristic molecular changes, which are essential for the metastatic dissemination of tumor cells. In this review, we will discuss recent insights into pro-metastatic events occurring in tumor cells themselves and in the tumor stroma. Tumor cell-intrinsic alterations include the loss of cell polarity and alterations in cell-cell and cell-matrix adhesion as well as deregulated receptor kinase signaling, which together support detachment, migration and invasion of tumor cells. On the other hand, the tumor stroma, including endothelial cells, fibroblasts and cells of the immune system, is engaged in an active molecular crosstalk within the tumor microenvironment. Subsequent activation of blood vessel and lymph vessel angiogenesis together with inflammatory and immune-suppressive responses further promotes cancer cell migration and invasion, as well as initiation of the metastatic process. Received 4 July 2005; received after revision 3 November 2005; accepted 14 November 2005     

On the prevention of haematogenous tumour metastasis to liver and lung

Summary Vascular endothelium is lined by a layer of alpha, 2, macroglobulin (AMG). This protide is believed to regulate the rate of extravasation of tumor cells. Experiments are described which show that increasing the deposition of AMG (enhancing its production and blocking its lysis) reduces the incidence of tumour metastases to liver and lung.     

A simple procedure for removal of intra- and extra-tumoral macrophages from primary tumor cultures

Summary Improved growth of tumor cells in primary cell suspensions isolated from solid tumors can be achieved by addition of an antifungal agent, mycostatin, to the culture medium. Mycostatin inhibits the cytotoxicity of macrophages and also quickly detaches phagocytes without any apparent retardation of the growth of tumor cells. This method is particularly useful for obtaining cultures of lung tumor cells or cells from lung metastases of other tumors.This research was supported in part by grants CA-22839 and CA-28482 awarded by the National Cancer Institute, DHEW, USA. This is publication No. 406 from the Department of Basic and Clinical Immunology and Microbiology, Medical University of South Carolina.We thank Charles L. Smith for editorial assistance. Address correspondence to Y. Y., Department of Basic and Clinical Immunology and Microbiology, Medical University of South Carolina, 171 Ashley Avenue, Charleston, SC 29403, USA.     

High glucose-induced enzyme activity changes in cultured cell lines established from the kidneys of Chinese hamsters with aglycosuria or spontaneous glycosuria

Summary Chinese hamster kidney epithelial-like cells derived from highly inbred nondiabetic (AV) and diabetic (XA) genetic sublines were passaged in medium containing 100 or 400 mg/dl glucose. The effect of high medium glucose on the activities of 5 enzymes involved in glucose metabolism was followed and significant glucose-dependent difference was observed. The effects, however, were opposite in cells derived fromAV andXA sublines.     

A gelatin sponge model for studying tumor growth: quantitation of tumor cells and leukocytes in the CHO tumor

A gelatin sponge model system for tumor cell inoculation and retrieval of tumor-associated leukocytes is described. Gelatin sponges pre-implanted in nude mice harboring tumorigenic Chinese hamster ovary cells (line CHO) were examined at 2 and 11 days after injection of tumor cells for tumor cell content and leukocyte accumulation after digesting the sponge matrix in collagenase solution. The data indicate a progressive influx of host cells consisting primarily of macrophages, neutrophils and lymphocytes. The total number of viable tumor cells as well as the fraction of surviving tumor cells with clonogenic potential also increased with tumor age. Blank sponges not harboring tumor cells elicited an inflammatory response in the animals which did not change appreciably with length of sponge residence. However, when the sponges were harboring tumor cells, the accumulation of host leukocytes far exceeded that which occurred in blank sponges. This observation suggests a host response directed toward the tumor which is absent in animals bearing blank sponges. Apart from providing anchorage for injected cells, the gelatin sponge, by virtue of its digestibility in collagenase, makes possible the easy retrieval and precise quantitation of tumor-associated host cells.     

Quantitation of proinsulin mRNA sequences in hamster insulinoma cells in culture by molecular hybridization

Summary The content of proinsulin mRNA sequences was measured in a cultured cell line established from a transplantable hamster islet cell tumor, by hybridization with proinsulin cDNA. The cells cultured in vitro were found to contain a significant amount of proinsulin mRNA sequences, compared with non-insulin-producing hamster tissues, and seem to be a useful system for the study of insulin gene expression.This work was supported in part by Grants-in-Aid Scientific Research (248129, 387065, 337013, 378052) and a Grant-in-Aid for Cancer Research (301538) from the Ministry of Education, Science and Culture, Japan.     

Immunohistochemical localization fo galactocerebroside in kidney,liver, and lung of golden hamster

Summary Localization of galactocerebroside in kidney, liver, and lung of hamster was studied by the immunoperoxidase method using an affinity-purified specific antibody. Epithelial cells of the following anatomical sites were labelled with the antibody: distal tubuli, ascending limbs of Henle's loops, and collecting tubuli in kidney; periportal bile ducts and hepatic parenchyma in liver; bronchioli and alveoli in lung. The existence of galactocerebroside in these 3 organs was also confirmed by chemical analysis.This study was supported in part by grants from the Ministry of Education, Science and Culture of Japan, a Research Grant for Intractable Diseases from the Ministry of Health and Welfare of Japan, and a grant from the Mitsubishi Foundation.     

Factor(s) from nonmacrophage bone marrow stromal cells inhibit Lewis lung carcinoma and B16 melanoma growth in mice

Bone marrow stroma produces positive and negative growth regulators which constitute the hematopoietic microenvironment. As many tumors metastasize to the bones, these regulators may also influence tumor growth. Hematopoietic cytokines may indeed exert both positive and negative effect on tumor growth. We report that, when mixed with tumor cells. adherent bone marrow cells inhibit primary tumor growth and metastases formation in mice transplanted with Lewis lung carcinoma or B16 melanoma. Peritoneal macrophages or lymph node cells did not exert any influence. The tumor inhibition was apparently due to soluble factor(s) released by marrow stromal cells. In cocultures with B16 melanoma cells, adherent bone marrow cells exerted a significant antiproliferative effect which was increased by previous culture of the bone marrow cells with granulocyte-macrophage colony-stimulating factor but not with macrophage colony-stimulating factor. Neither neutralizing antibodies against tumor necrosis factor-alpha, transforming growth factor-beta or interferon alpha/beta nor addition of Escherichia coli lipopolysaccharide to generate inflammatory cytokines could affect the antiproliferative effect of bone marrow stromal cells. The bone marrow stroma factor(s) which inhibit tumor growth might, therefore, be a novel growth regulator.     

Localization of integrated adenovirus DNA in the hamster genome

Adenovirus DNA integrated into the genomes of adenovirus-transformed hamster cells or of adenovirus type 12 (Ad12)-induced hamster tumor cells can be located at many different chromosomal sites. This raises the question as to whether distinct isochores of the hamster cell genome might be more accessible to recombination with adenovirus DNA. In Ad12- or Ad2-transformed hamster cell lines, and in Ad12 revertants, the investigated integrated viral DNA sequences were assigned to isochore families by analyzing DNA fractions from preparative CsCl density gradients for their buoyant densities (and, therefore, GC levels) and for the presence of viral DNA. Adenovirus DNA sequences were found in different isochores, which did not generally match the base composition of viral sequences. This is in apparent contrast to what was previously observed with retroviral integration. However, in cell lines carried in culture for many years, the viral DNA sequences might have been transposed to different isochore positions, since the host sequences flanking the viral DNA appear to have been conserved.Received 6 July 2004; received after revision 23 August 2004; accepted 6 October 2004     

A gelatin sponge model for studying tumor growth: quantitation of tumor cells and leukocytes in the CHO tumor

Summary A gelatin sponge model system for tumor cell inoculation and retrieval of tumor-associated leukocytes is described. Gelatin sponges pre-implanted in nude mice harboring tumorigenic Chinese hamster ovary cells (line CHO) were examined at 2 and 11 days after injection of tumor cells for tumor cell content and leukocyte accumulation after digesting the sponge matrix in collagenase solution.The data indicate a progressive influx of host cells consisting primarily of macrophages, neutrophils and lymphocytes. The total number of viable tumor cells as well as the fraction of surviving tumor cells with clonogenic potential also increased with tumor age. Blank sponges not harboring tumor cells elicited an inflammatory response in the animals which did not change appreciably with length of sponge residence. However, when the sponges were harboring tumor cells, the accumulation of host leukocytes far exceeded that which occurred in blank sponges. This observation suggests a host response directed toward the tumor which is absent in animals bearing blank sponges. Apart from providing anchorage for injected cells, the gelatin sponge, by virtue of its digestibility in collagenase, makes possible the easy retrieval and precise quantitation of tumor-associated host cells.Supported by the United States Department of Energy and National Institutes of Health Grant P41-RR01315.     

Vascular permeability in malignant disease

Summary Experimental demonstration that vessels draining large tumours are impermeable to cellular elements. Thus the pulmonary vessels of animals bearing large, primary (other than gastro-intestinal) cancers can become impermeable to tumour emboli. This imperviousness prevents the establishment of secondaries in the lung and promotes the transpulmonary passage of tumor cells. This phenomenon may account for the development of paradoxical metastases.     

Tumor cell migration in complex microenvironments

Tumor cell migration is essential for invasion and dissemination from primary solid tumors and for the establishment of lethal secondary metastases at distant organs. In vivo and in vitro models enabled identification of different factors in the tumor microenvironment that regulate tumor progression and metastasis. However, the mechanisms by which tumor cells integrate these chemical and mechanical signals from multiple sources to navigate the complex microenvironment remain poorly understood. In this review, we discuss the factors that influence tumor cell migration with a focus on the migration of transformed carcinoma cells. We provide an overview of the experimental and computational methods that allow the investigation of tumor cell migration, and we highlight the benefits and shortcomings of the various assays. We emphasize that the chemical and mechanical stimulus paradigms are not independent and that crosstalk between them motivates the development of new assays capable of applying multiple, simultaneous stimuli and imaging the cellular migratory response in real-time. These next-generation assays will more closely mimic the in vivo microenvironment to provide new insights into tumor progression, inform techniques to control tumor cell migration, and render cancer more treatable.     

Serum activity inhibiting specific simian virus 40-induced transplantation resistance and its correlation with primary SV40 tumors appearance in hamsters.

Using the modified technique of transplantation test, ITR serum activity was found in most (14 out of 21) individual hamster sera obtained during the latent period of primary SV40 carcinogenesis (60 days after virus infection when newborn). On the other hand, as a rule, no ITR activity was observed in the sera of the same hamsters after tumor appearance and during their growth. ITR activity rapidly disappeared from sera of hamsters neonatally infected with SV40 after their successful immunization with the same virus during the latent period. There appears to be a correlation between the presence of ITR serum factor during the latent period and the subsequent primary SV40 tumor appearance in hamsters.     

Serum activity inhibiting specific simian virus 40-induced transplantation resistance and its correlation with primary SV40 tumors appearance in hamsters

Summary Using the modified technique of transplantation test, ITR serum activity was found in most (14 out of 21) individual hamster sera obtained during the latent period of primary SV40 carcinogenesis (60 days after virus infection when newborn). On the other hand, as a rule, no ITR activity was observed in the sera of the same hamsters after tumor appearance and during their growth. ITR activity rapidly disappeared from sera of hamsters neonatally infected with SV40 after their successful immunization with the same virus during the latent period. There appears to be a correlation between the presence of ITR serum factor during the latent period and the subsequent primary SV40 tumor appearance in hamsters.Acknowledgment. The author wishes to thank Dr Galina I. Deichman for continuing advice and encouragement during the course of these studies.     

Analysis of OCT4 expression in an extended panel of human tumor cell lines from multiple entities and in human mesenchymal stem cells

OCT4 is considered a main regulator of embryonic stem cell pluripotency and self renewal capacity. It was shown that relevant OCT4 expression only occurs in cells of embryonic pluripotent nature. However, several recent publications claimed to have demonstrated OCT4 expression in human somatic tumor cells, human adult stem or progenitor cells and differentiated cells.We analysed 42 human tumor cell lines from 13 entities and human bone marrowderived mesenchymal stem cells (MSC). To validate OCT4 expression we used germ cell tumor (GCT) cell lines, derived xenografts and GCT samples. Analysis by RT-PCR, western blotting, immunocytochemistry and immunohistochemistry was performed. With exception of typical embryonal carcinoma cells, we did not observe reliable OCT4 expression in somatic tumor cell lines and MSC. We suggest that a high level of expression of the OCT4 protein together with its nuclear localization still remains a reliable and definitive feature of cells with embryonic pluripotent nature. Received 30 September 2008; received after revision 05 November 2008; accepted 10 November 2008