Epidemiologic aspects of malignant melanoma (review)

The incidence of malignant melanoma has increased worldwide, the rate in Germany being about 12 per 100,000. Geographic variations are due to genetic or racial factors rather than to excess sun exposure. A white complexion with freckles or multiple dysplastic nevi are important danger signs. Large and even small congenital nevi are potential precursors to melanoma. The prevention of melanoma is based on the recognition of risk factors, the identification and removal of precursor lesions and an improved detection of initial melanomas by physicians and lay persons. The so-called millimeter rule has proved to be useful in this connection.     

Methodological aspects of phase-I studies of novel anticancer agents (review)

In the last 5 years we have performed 14 phase I studies in our department. Eight of these trials involved evaluation of both the clinical and the pharmacokinetic behaviour of novel anti-cancer agents. The remainder investigated various aspects of drug delivery, targetting or resistance modification with existing anti-cancer drugs. In total these studies have involved over 200 patients. In this review article we have drawn upon our experience to suggest guidelines for future studies.     

Morphological aspects of basement-membranes and their receptors in benign and malignant neoplasms (review)

We review the current knowledge on alterations of the major basement membrane (BM) components and their cellular integrin receptors in benign and malignant tumors of epithelial and mesenchymal origin. While benign tumors usually exhibit a continous BM, recent analyses provide evidence that invasive growth of carcinomas coincides with (a) a loss in a proper BM, (b) changes in the type of integrin receptor expression and (c) the retained ability of certain tumor cells to synthesize matrix components. This latter aspect has been regarded as a potentially beneficial 'host' mechanism against invasive growth. This assumption is strongly supported by the finding of a positive correlation between the extent of BM loss and both a lesser degree of tumor differentiation and a worse prognosis of tumor growth. The resulting concept indicates that in carcinomas an imbalance in the cell-matrix interaction is the leading element in invasive growth. In mesenchymal tumors a somewhat different role of the BM can be observed. Thus, the qualitative and quantitative expression of major BM components in benign mesenchymal tumors closely relates to the BM pattern of normal tissues providing a histogenetically oriented classification of benign mesenchymal tumors. Most well-differentiated sarcomas retain a BM pattern close to that of the histogenetically related tissue, although in poorly differentiated sarcomas no such attribution to a histogenetic orientation of the tumor cells can be found.     

Enhancement of the antiproliferative activity of cis-diamminedichloroplatinum(II) by quercetin

We have shown previously that the flavonoid quercetin (3,3',4',5,7-pentahydroxyflavone) enhances the antiproliferative activity of cis-diamminedichloroplatinum(II) (cis-DDP) in vitro. In order to investigate whether this observation could be exploited in cancer treatment, we tested this drug combination in human tumor xenografts. The established human large-cell cancer of the lung (LXFL 529) was implanted s.c. into nude mice. Tumors were allowed to grow to a mean diameter of approximately 5 mm and the animals were subsequently treated intraperitoneally with quercetin, cis-DDP or a combination of both. Treatment was given 3 times at 3-day intervals. Twenty milligrams quercetin per kg body weight caused no inhibition in tumor growth compared to untreated controls; 3 mg cis-DDP per kg body weight with the same time schedule reduced tumor growth, compared to quercetin-treated and control animals. Concomitant treatment with 20 mg quercetin and 3 mg cis-DDP per kg body weight reduced tumor growth to a significantly greater degree than cis-DDP alone. Toxicity of this treatment was relatively low as determined by measurements of the body weight of the mice. A combination of 4 mg or 5 mg cis-DDP with 20 mg quercetin per kg body weight also reduced tumor growth compared to single cis-DDP treatment. The toxicity of treatment with these increased doses was high, as shown by the high lethality and the loss of body weight of surviving animals.     

Protection of antiproliferative effect of cis-diamminedichloroplatinum (II) by sodium thiosulfate

Summary Utilizing the phytohemagglutinin (PHA) stimulation assay of human peripheral blood mononuclear cells (PBM), the protective effect of sodium thiosulfate (STS) on the antiproliferative action of cis-diamminedichloroplatinum (II) (DDP) against human cells was investigated. DDP alone significantly inhibited the proliferation of PBM over the concentration range of 10^-7 to 5x10^-5 M. The antiproliferative effect of DDP was significantly blocked when STS was added to the stimulation culture at the time of exposure to DDP at molar STS/DDP ratios of more than 500. However, STS at molar ratios of less than 100 induced minimal protection. Then, STS was added at various times after DDP exposure with a molar STS/DDP ratio of 1000. The protection was effective within 10 min after exposure to DDP at a concentration of 5x10^-5 M, whereas it was not effective beyond 30 min after the exposure. The results indicate that effective protection against DDP cytotoxicity in human cells can be achieved by the concurrent presence of STS with molar STS/DDP ratios of more than 500, but not when a molar STS/DDP ratio of less than 100 is used.     

The development of anthracycline analogs (review)

The anthracycline class of antitumour agents have the widest spectrum of activity of all drugs used to treat malignant disease. Consequently they are ubiquitous in their use worldwide, but are not without problems. The abrogation of cardiac toxicity and the development of drug resistance has been attempted by modifying the molecule chemically, producing over 1000 structural analogues since the discovery of Daunorubicin in the late 1950's. This review charts this developmental process and points to the possible future of this important class of drugs.     

The interaction between protein-kinase-C (pkc) and estrogens (review)

The interactions between protein kinase C (PKC) and the steroid hormone estradiol or its receptor (ER) are reviewed. Estradiol upregulates PKC both in vitro and in vivo in the ovary, the anterior pituitary and in mammary tissue of several mammalian species. The antiestrogen tamoxifen inhibits PKC. Activation of PKC leads to a marked decrease of ER protein and ERmRNA in human breast cancer cells and some other cell lines. Inhibition or down-regulation of PKC enhances ER binding. These results indicate that there are links between the PKC signal transduction pathway and the steroid receptor family. Further studies are needed to clarify the role of PKC isoforms in normal and cancerous tissues which are known to be influenced by estradiol.     

The aberrant p53 protein (review)

According to the current concept of carcinogenesis, neoplastic transformation consists of multistep accumulations of adverse genetic and epigenetic events. Recent advances in molecular genetics have demonstrated aberrations of oncogenes and tumor-suppressor genes in a variety of human cancers. The loss of wild-type p53 gene expression has exceptionally been implicated in the development of a wide variety of human cancers and it is generally accepted that p53 is a component in biochemical pathways central to human carcinogenesis. Although the role of the p53 gene in cancer genesis and development has fueled as many questions, study of p53 has come to the forefront of cancer research and detection of its abnormalities during the development of tumors may have diagnostic, prognostic and therapeutic implications. To be of value in clinical practice, immunohistochemical assessment of p53 protein should provide clinically relevant information. The degree of concordance between p53 gene mutation and the accumulation of p53 protein cannot be perfect, however, the immunohistochemical assay using anti-p53 antibodies is the most widely applicable approach for detection of tumors in routine investigations, particularly with regard to diagnosis or prognosis.     

The phosphorylation connection to cancer (review)

Despite our incomplete comprehension of how growth factor-stimulation of cells is linked to the cell cycle and of how the G(1)/S checkpoint is linked to initiation in DNA replication there is an unparalleled wealth of experimental evidence to connect protein phosphorylation to molecular mechanisms of carcinogenesis. Many growth factors, growth factor receptors with tyrosine kinase activity (insulin receptor, EGFR, PDGFR, CSF1R, NGFR, HGFR), nonreceptor serine/threonine or tyrosine kinases (c-Raf-1, cMos, c-Abl, c-Src) and cyclin D1 are encoded by oncogenes mutated or overexpressed in a variety of human tumors; the physiological functions of oncoproteins that are involved in gene expression and replication (c-Jun, T-antigen, c-Myc, c-Myb) as well as p53, RB and CDK4 tumor suppressor proteins and replication factor A are also regulated by phosphorylation, ms genes transduce growth factor receptor signals to protein kinase C (PKC) or to c-Raf-1 triggering two different cascades of protein kinases, the PKC and MAPK signaling pathways both targeting nuclear proteins. Thus cancer can be considered as a disease of the signaling pathways.     

The tumor microenvironment in hepatocellular carcinoma (review)

The tumor microenvironment has been largely studied as a dynamic system orchestrated by inflammatory cells, including cancer cells, stroma as well as the extracellular matrix. It is useful to describe and predict the phenotypic characteristics of cancer. Furthermore, a better understanding of its interplay with the various aspects of the tumor cells may be utilized for the discovery of novel molecular targets. Liver cancer is considered a model of the relation occurring between the tumor micro-environment and tumor development. The chronic inflammatory status of the liver, sustained by the infection of hepatitis viruses, as well as the production of cytokines and growth factors within the parenchyma, lead to an intricate microenvironment. The identification of novel molecular therapeutic targets may improve the outcome of patients with liver cancer as it remains the third leading cause of cancer death worldwide. In the present study, the tumor microenvironment in hepatocellular carcinoma (HCC) was explored by a review of the literature. Studies on hepatitis virus infections and the consequent chronic inflammatory status were examined. In this context, immune-mediated and/or virus-related molecular mechanisms have been hypothesized as being responsible for liver cancer development. The interlink among HCC microenvironment components, comprising cellular elements, cytokines, growth factors and several proteins is also described together with the role of matrix metalloproteinases in HCC development. Finally, the rationale for targeting tumor-stromal interface is summarized in the context of new therapeutic opportunities.     

The role of hyaluronan in tumour neovascularization (review)

Tumour growth and metastasis are totally dependant upon neovascularization. The target cell for tumour neovascularization is the blood-vessel endothelial cell, and specific angiogenic molecules produced or induced by the tumour are believed to initiate the process. In this report, we review one of these angiogenic molecules, the glycosaminoglycan hyaluronan (HA), which appears to have differing roles in neovascularization depending on its molecular mass. High-molecular-mass HA is anti-angiogenic whereas oligosaccharides of HA, of specific size, actively stimulate endothelial-cell proliferation and migration, 2 of the key events associated with neovascularization, and induce angiogenesis in vivo. We provide details of the action of HA oligosaccharides on endothelial cells, from binding to cell-surface receptors, through activation of signal transduction pathways and gene expression to protein synthesis, cell proliferation and cell migration. We also suggest a model to account for HA of differing molecular mass being present, at different locations, within a single tumour and how this HA aids both general tumour growth and tumour metastasis.     

The role of serotonin in tumour growth (review)

Serotonin (5-hydroxytryptamine; 5HT) a monoamine neurotransmitter mediates a wide range of physiological actions in the human body. For example 5HT is implicated in psychiatric and neurological disorders and also plays a fundamental role in tumour growth, differentiation and gene expression. 5HT acts as a growth factor for several types of tumoural and non-tumoural cells. This review considers the role of 5HT and its receptors in the human body with particular reference to carcinogenesis. We conclude that 5HT causes growth proliferation and 5HT antagonists cause growth inhibition in a variety of tumour cells (e.g. prostate carcinoma, lung carcinoma and colonic carcinoma). Therefore, further studies should look into the potential use of 5HT antagonists in the treatment of cancer.     

Induction of arginosuccinate synthetase (ASS) expression affects the antiproliferative activity of arginine deiminase (ADI) in melanoma cells

Arginine deiminase (ADI), an arginine-degrading enzyme, has been used in the treatment of tumours sensitive to arginine deprivation, such as malignant melanoma (MM) and hepatocellular carcinoma (HCC). Endogenous production of arginine is mainly dependent on activity of ornithine transcarbamylase (OTC) and argininosuccinate synthetase (ASS) enzymes. We evaluated the effect of ADI treatment on OTC and ASS expression in a series of melanoma cell lines. Twenty-five primary melanoma cell lines and normal fibroblasts as controls underwent cell proliferation assays and Western blot analyses in the presence or absence of ADI. Tissue sections from primary MMs (N = 20) and HCCs (N = 20) were investigated by immunohistochemistry for ASS expression. Overall, 21/25 (84%) MM cell lines presented a cell growth inhibition by ADI treatment; none of them presented constitutive detectable levels of the ASS protein. However, 7/21 (33%) ADI-sensitive melanoma cell lines presented markedly increased expression levels of the ASS protein following ADI treatment, with a significantly higher IC50 median value. Growth was not inhibited and the IC50 was not reached among the remaining 4/25 (16%) MM cell lines; all of them showed constitutive ASS expression. The OTC protein was found expressed in all melanoma cell lines before and after the ADI treatment. Lack of ASS immunostaining was observed in all analyzed in vivo specimens. Our findings suggest that response to ADI treatment in melanoma is significantly correlated with the ability of cells to express ASS either constitutively at basal level (inducing drug resistance) or after the treatment (reducing sensitivity to ADI).     

Antibody directed enzyme prodrug therapy (ADEPT): A review of some theoretical, experimental and clinical aspects

The concept of generating cytotoxic agents from non-toxic prodrugsat tumour sites by antibody vectored enzyme introduces a widerange of opportunities. Various prodrugenzyme combinations havebeen described and encouraging results reported in xenograftmodels. Whilst the mouse model is a valuable tool in this approachtranslation to the human patient may expose more complex issues.The objective of restricting drug action to tumour sites andthus allowing greatly increased cytotoxic action requires moreprecise restriction of enzyme activity to rumour sites thanhas been achieved with an antibody vector and natural clearancealone. Assisted clearance mechanisms have been found effective.Alternatively, or additionally, the difference between prodrugand active drug creates the opportunity to degrade active drugselectively in blood and thus protect normal tissues. In order to give more than one cycle of treatment it will benecessary for the antibody-enzyme conjugate to be nonimmunogenicor for the concurrent administration of immunosuppressive agents. A pilot scale clinical trial with a prototype prodrug indicatedthe feasibility of antibody directed enzyme prodrug therapy(ADEPT) targeting, antibody-enzyme conjugates, clearing antibody, prodrugs, colorectal cancer, ‘ADEPT’     

Cancer-related fatigue (review)

Fatigue is one of the most common complaints of people with cancer. It affects the majority of patients actively undergoing cancer related therapies, but also a meaningful number of those who successfully completed therapy and are disease-free and potentially cured at the end of the treatments. In cancer setting, fatigue is to be defined as a chronic form of tiredness, which is perceived by the patient as being unusual or abnormal, and absolutely disproportionate with respect to the amount of exercise or activity he/she has carried out and which is not removed by resting or sleeping. The exact cause of fatigue is not known. In cancer setting there are many contributing or associated factors, such as cancer itself, cancer treatment (chemotherapy, radiation therapy, immunotherapy and surgery), depression or anxiety, some medications, pain, nausea, vomiting or diarrhea, poor nutrition, anemia, infections, insomnia. There is no standard of care for the assessment or treatment of fatigue in patients with cancer. The evaluation of fatigue is intrinsically multidimensional, even though the lack of objective measurement methods makes it difficult to draw up worldwide-accepted guidelines; nonetheless, a number of methods have been developed to assess it. Treatment of fatigue should depend on its cause, but presently it is still addressed against the associated symptoms rather than fatigue itself. Useful approaches includes erythropoietin alpha, psychostimulants, medications to treat pain, depression, nausea and difficult sleeping, physical therapy for reconditioning exercises or energy saving techniques, health education. In this report some of the crucial issues related to fatigue in people with cancer are reviewed.     

Clonality of malignant-tumors (review)

Heterogeneous descendants are continuously produced in tumor cell evolution, although the first step of carcinogenesis may involve a single clone. From the data obtained by molecular biology, we have to recognize that the 'clonality of tumor' proliferated from a single clone does not confirm the genetic identity of tumor cell society. The so-called 'multi-hit hypothesis' can not explain this heterogeneity, since this hypothesis only describes serial changes of genes in carcinogenesis. However, genetic alterations actually accumulate progressively after carcinogenesis until the end of total cell death. Genetic alterations in tumor evolution are a stochastic process rather than a non-stochastic one, since 'neutral evolution' in molecules occurs in micro-environments, It is an essential concept that retrospective analysis can never demonstrate the clonal origin of tumors, because the genetic pool of tumor cell society is unstable and changes proliferation-dependently.