Immunology of metastasis. Can the immune response cope with disseminated tumor?

Phytochemicals as Immunomodulatory Molecules in Cancer Therapeutics

Phytochemicals are natural plant-derived products that provide significant nutrition, essential biomolecules, and flavor as part of our diet. They have long been known to confer protection against several diseases via their anti-inflammatory, immune-regulatory, anti-microbial, and several other properties. Deciphering the role of phytochemicals in the prevention, inhibition, and treatment of cancer-unrestrained cell proliferation due to the loss of tight regulation on cell growth and replication-has been the focus of recent research. Particularly, the immunomodulatory role of phytochemicals, which is pivotal in unchecked cell proliferation and metastasis, has recently been studied extensively. The immune system is a critical component of the tumor microenvironment, and it plays essential roles in both preventing and promoting oncogenesis. Immunomodulation includes stimulation, amplification, or inactivation of some stage(s) of the immune response. Phytochemicals and their products have demonstrated immune regulation, such as macrophage migration, nitric oxide synthase inhibition, lymphocyte, T-cell, and cytokine stimulation, natural killer cell augmentation, and NFκB, TNF, and apoptosis regulation. There is a dearth of extensive accounts of the immunomodulatory effects of phytochemicals in cancer; thus, we have compiled these effects with mechanistic aspects of dietary phytochemicals in cancer, highlighting promising candidates and ongoing clinical trials on immunotherapeutic strategies to mitigate oncogenesis.

Paracrine and autocrine growth mechanisms in tumor metastasis to specific sites with particular emphasis on brain and lung metastasis

Once metastatic cells successfully seed at distant sites, their clinical detection and danger to the host are dependent on growth to form gross metastases. Metastatic tumor cells proliferate in response to local paracrine growth factors and inhibitors, and their growth also depends on production and responses to autocrine growth factors. A major organ-derived (paracrine) growth factor from lung tissue-conditioned medium has been isolated that differentially stimulates the growth of cells metastatic to brain or lung. Characterization of this mitogen demonstrated that it is a transferrin or a transferrin-like glycoprotein. Furthermore, antibodies to transferrin can remove significant growth activity from lung tissue-conditioned medium. Cells that are metastatic to brain or lung express greater numbers of transferrin receptors on their surfaces than cells that are poorly metastatic or metastatic to liver. Growth responses of metastatic cells and organ preferences of colonization appear to change during progression to more malignant states. At early stages of metastatic progression there is a tendency for many common malignancies to metastasize and grow preferentially at particular sites, suggesting that paracrine growth mechanisms may dominate the growth signals at this stage of progression. In contrast, at later stages of metastatic progression widespread dissemination to various tissues and organs occurs, and autocrine growth mechanisms may dominate the growth responses of metastatic cells. Ultimately, the progression of malignant cells to completely autonomous (acrine) states can occur, and at this stage of metastatic progression cell growth may be completely independent of autocrine and paracrine growth factors or inhibitors.

Bone metastases of hepatocellular carcinoma after liver resection

Between January 1985 and July 1990, 323 cases of hepatocellular carcinoma underwent liver resection in our department. Bone metastases were found in 12 of these cases (3.7%). Bone metastases were mainly found in vertebral bone (58.3%) and pelvic bone (41.7%). The time interval to the development of bone metastasis after liver resection was closely related to the presence of intrahepatic metastasis and the stage at operation. In all cases, the initial clinical symptom was pain and/or motor disturbance. Radiotherapy was performed in 10 cases and transcatheter arterial embolization or surgery was performed in 4 cases. The pain or neurological symptoms improved with these therapies in all cases. Cumulative survival was 1 year in 74%, 2 years in 34%, and 3 years in 17%, respectively.

Effect of splenectomy upon the growth of B16-F10 melanoma and its relation to the interferon system

The influence of splenectomy upon the growth of B16-F10 malignant melanoma and changes in interferon-synthesizing ability in mice were studied. Surgical stress alone temporarily diminished the ability of mice to respond to interferon induction by poly rIrC. Two weeks following the surgery, mock-splenectomized mice fully regained their interferon synthesis ability. However, this was not true in the case of splenectomized mice. They remained refractory to interferon induction. The removal of the spleen had no obvious effect on the rate of pulmonary metastasis in mice injected with B16-F10 malignant melanoma in relation to the mock-splenectomized or control mice. Mice that were splenectomized and inoculated with B16-F10 melanoma also remained refractory to interferon induction.

Use of NeoR B16F1 murine melanoma cells to assess clonality of experimental metastases in the immune-deficient chick embryo

Recent work on molecular and genetic aspects of metastasis has emphasized the need for assays in immune-deficient animal hosts. The commonly used assays in athymic nude mice may not always be appropriate, and assays in other hosts are required. We have developed a metastasis assay in the naturally immune-deficient chicken embryo. As part of our characterization of this assay we have examined the clonality of individual experimental (i.v.-derived) metastases in this host. For these studies we developed a cell line, B16-Neo, from parental B16F1 murine melanoma cells. B16-Neo cells carry a stable drug-resistance marker, the bacterial neo gene, which confers resistance to the drug G418, but are unaltered in experimental metastatic properties in the chick embryo relative to parental B16F1 cells. We observe that the majority of individual liver tumors that arise following i.v. injection of mixtures of these cells contain cells of a single marker phenotype and are likely to be clonal in origin. These results are similar to those obtained by others for metastases in immune-competent mice, suggesting similar mechanisms of metastasis formation in these two systems. In both hosts it should be noted, however, that a small but significant proportion of metastases appear not to be clonal in origin.

Influence of host defenses on the hepatic colonization of B16F10 melanoma cells

To investigate the significance of host immunity in metastasis we have simultaneously evaluated metastatic development and the tumoricidal action of host defenses in an experimental system for liver metastasis which involves the intrasplenic injection of B16F10 melanoma cells in syngeneic mice. In addition, three experimental groups were treated with immunosuppressive doses of cyclosporin A (CsA) during the following periods of the malignant process: 1st-5th days, 1st-12th days and 7th-12th days. Analysis of cytolytic effects of macrophages, NK cells and T-lymphocytes on tumor cells reveals a decay in antitumor immunity from the 7th day to the 12th day and a marked resistance of B16F10 melanoma cells derived from hepatic metastases to T-lymphocytes and NK cells. The 1st-5th day CsA treatment of tumor-bearing mice produced a reduction in both T-lymphocyte and macrophage reactions against tumor cells and a significant increase in the 7th day micrometastasis incidence in the liver. Once micrometastases have been established the CsA-treatment suppression on the 5th day allows the tumor growth rate in these mice to become the same as in controls. However, the 7th-12th day CsA treatment produces a clear inhibitory effect on focal metastatic development which may correspond to the in vitro antiproliferative effect of CsA, detected on cultured B16F10 melanoma cells.

Tumor cell metastasis

Local tissue invasion and the formation of metastatic lesions are characteristic properties of many malignant tumors. The formation of metastases is a complex process involving the passage of tumor cells from the site of the primary bulk tumor through successive connective tissue barriers, ultimately resulting in the growth of secondary tumor cell colonies in distinct target organ locations. At many stages in the metastatic process, tumor cells interact with multiple components of the extracellular matrix. Recently, the importance of basement membrane as a barrier to invasive cells has been recognized. In the course of the transition from in situ to invasive carcinoma, normal or dysplastic epithelial cells residing on a basement membrane are replaced by neoplastic cells which subsequently invade the basement membrane and enter the underlying stroma. Once in the stroma, tumor cells can then penetrate the walls of blood vessels or the lymphatic system and enter into the circulation. Circulating tumor cells next arrest in the lumina of small vessels, invade the vessel wall, and leave the circulation. These cells are now directly exposed to the extracellular matrix of a target organ where they may grow to form secondary tumors. Throughout the metastatic process tumor cells are thus in contact with, and are potentially responsive to, various components of the extracellular matrix. This review provides a survey of the recent advances in our understanding of the interactions of metastatic tumor cells with the extracellular matrix. Specifically, the role of basement membrane as a barrier to metastatic tumor cells is examined.

Cancer metastasis: experimental approaches, theoretical concepts, and impacts for treatment strategies

It has been the purpose of this article to describe recent advances in cancer metastasis research. Clinical realities and experimental approaches to the study of underlying basic mechanisms of metastasis formation were discussed. Wherever possible, results were reported which led to the development of theoretical concepts. Such results and concepts were finally evaluated in light of their possible impact for the design of new treatment strategies. Experimental findings from many diverse research fields were summarized with the help of tables, figures, and references. It was concluded that the process of metastasis is a dynamic event that can be described as a sequence of interrelated steps. Experimental results indicated that malignant cells that migrate and disseminate from the primary organ to distant sites and there eventually develop into metastases have to survive a series of potentially lethal interactions. Intimate tumor-host interactions were reported to take place all along the metastatic process. They were elucidated at the steps of angiogenesis, invasion, organ interaction, dormancy, tumor rejection, and tumor immune escape. The outcome of such tumor-host interactions seemed to depend on intrinsic properties of the tumor cells themselves as well as on the responsiveness of the host. Metastasis does not appear as a merely random process. Both clinical and experimental studies revealed that the whole process can be described more appropriately in terms of stochastic, sequential, and selective events, each of which is controlled and influenced by a number of mechanisms. With regard to therapeutic intervention, a selective event offers more possibilities than a random one because it is governed by rules that can be exploited experimentally. Various impacts from experimental studies for the design of antimetastatic cancer treatment strategies were discussed. Sequential steps of the metastatic cascade could become new therapy targets. Conventional empirically derived treatment modalities should become flanked by methods aimed more specifically at critical steps of cancer spread in order to prevent progression of the disease. This is where basic research on mechanisms could make significant contributions to therapy planning in the future. Furthermore, possible negative effects of surgery, radiotherapy, and adjuvant chemotherapy or immunotherapy that could result in enhancement of metastatic progression need to be critically evaluated to limit them as much as possible.(ABSTRACT TRUNCATED AT 400 WORDS)

New hope for identifying the unidentified. The National Crime Information Center unidentified person/missing person files

The National Crime Information Center Unidentified Person/Missing Person Files offer computer comparison of descriptive data on unidentified dead and living persons with data entered on missing persons. Completion of a simple, but detailed standard form allows entry of descriptors of physical characteristics, fingerprint classification, dentition, anthropologic and x-ray findings, optic prescriptions, medical devices, surgical procedures, serology, jewelry, and clothes. Medical and law enforcement agencies collect the descriptive data on the unidentified; families and law enforcement agencies collect missing persons information. Entry for both is via law enforcement regional or state NCIC computer terminals. Continuous comparison and cross search of both files is initiated upon entry of either form.