Predictive value of serum alkaline DNase activity variations in treatment of head and neck cancer

Tumor-derived cell-free DNA and circulating tumor cells: partners or rivals in metastasis formation?

The origin of metastases is a topic that has sparked controversy. Despite recent advancements, metastatic disease continues to pose challenges. The first admitted model of how metastases develop revolves around cells breaking away from the primary tumor, known as circulating tumor cells (CTCs). These cells survive while circulating through the bloodstream and subsequently establish themselves in secondary organs, a process often referred to as the "metastatic cascade". This intricate and dynamic process involves various steps, but all the mechanisms behind metastatic dissemination are not yet comprehensively elucidated. The "seed and soil" theory has shed light on the phenomenon of metastatic organotropism and the existence of pre-metastatic niches. It is now established that these niches can be primed by factors secreted by the primary tumor before the arrival of CTCs. In particular, exosomes have been identified as important contributors to this priming. Another concept then emerged, i.e. the "genometastasis" theory, which challenged all other postulates. It emphasizes the intriguing but promising role of cell-free DNA (cfDNA) in metastasis formation through oncogenic formation of recipient cells. However, it cannot be ruled out that all these theories are intertwined. This review outlines the primary theories regarding the metastases formation that involve CTCs, and depicts cfDNA, a potential second player in the metastasis formation. We discuss the potential interrelationships between CTCs and cfDNA, and propose both in vitro and in vivo experimental strategies to explore all plausible theories.

Evidence for cell-free nucleic acids as continuously arising endogenous DNA mutagens

There is extensive literature to show that nucleic acids can be taken up by cells under experimental conditions and that foetal DNA can be detected in maternal tissues. The uptaken DNA can integrate into host cell genomes and can be transcribed and translated into proteins. They can also cause chromosomal damage and karyotype alterations. Cell-free nucleic acids (cfNAs)-based non-invasive DNA diagnostic techniques are being extensively researched in the field of cancer with the potential to advance new prognostic parameters and direct treatment decisions. However, whether extracellular cfNAs that are released into circulation from dying cells as a consequence of normal physiology have any functional significance has not been explored. A recent study has demonstrated that circulating cfNAs have the ability to cause DNA damage and mutagenesis by illegitimately integrating into healthy cells of the body, thereby acting as mobile genetic elements. Fluorescently-labeled cfNAs isolated from sera of cancer patients and healthy volunteers were shown to be readily taken up by host cells followed by activation of a DNA-damage-repair-response which led their large scale integration into the host cell genomes. The latter caused dsDNA breaks and apoptosis in cells in vitro and in those of vital organs when injected intravenously into mice. Cell-free chromatin was consistently more active than cell-free DNA, while cfNAs derived from cancer patients were significantly more active than those from healthy volunteers. This study suggests that circulating extracellular cfNAs act as physiological continuously arising DNA mutagens with implications for ageing, cancer and a host of other degenerative human pathologies.

DNase I: structure, function, and use in medicine and forensic science

In this review, available structural data of deoxyribonucleases I (DNases I) from several mammalian species, hen, snake and frog are summarized. Comparative studies on enzymatic and immunological properties and glycosylation are discussed, and several evolutionary conclusions are presented. Over the past decade, the availability of new investigative tools, including sensitive methods of electrophoresis, detection and determination, and genetically modified DNase I models has resulted in a clearer understanding of the molecular mechanisms that connect the function and usefulness of DNase I in medicine and forensic science.

Circulating markers in squamous cell carcinoma of the head and neck: a review

Biological markers of disease enhance the ability to diagnose, treat and evaluate results of therapy and are especially intriguing for their potential use in the management of malignant tumours. The serum levels of various biochemical substances have been shown to be abnormal for many cancers and are utilised in the management of affected patients. Several markers have been thoroughly investigated for potential clinical utility in head and neck carcinoma. Although no single marker has been found to be adequately sensitive and specific, combinations of markers may improve the utility for some aspects of patient management. This review highlights the literature to date in the realm of circulating markers for head and neck carcinoma. A discussion of the potential usefulness and limitations of such markers follows.

Functional characterisation of serum DNase I in MRL-lpr/lpr mice

The autosomal defect in Fas antigen leads CD4-CD8-T-cells to accumulate in lymph nodes and spleen of MRL-lpr/lpr mice. MRL-lpr/lpr mice present increased levels of DNase I as compared to the control strain MRL-+/+. This DNase I, which most probably originates from the accumulated CD4-CD8-T-cells, cleaves nuclear DNA with a strong preference for internucleosomal sites yielding, in the presence of both Ca2+ and Mg2+, a pattern of fragments typical for apoptosis. Furthermore, we show that this "apoptosis-ladder" can be obtained with purified DNase I in presence of normal serum.

Influences of diet and surgical trauma on serum alkaline DNase activity levels

Changes in serum alkaline DNase activities might predict the therapeutic response in various malignant diseases. A decrease in serum alkaline DNase activity within days from the onset of therapy has been related to tumour necrosis and may be a possible sign of clinical response to effective treatment. To study if changes in serum alkaline DNase activity could be induced by non-tumour related tissue destruction, sera were collected on several occasions perioperatively in 18 patients undergoing surgery for benign gynaecological disease. Thirty apparently healthy women served as the control group. A significant decrease (P less than 0.001) in serum alkaline DNase activity was observed after an overnight fast in both groups of women. In contrast to the control women, the operated patients showed a significant decrease (P less than 0.001) in serum alkaline DNase activity throughout the operative period and 1 week postoperatively. We conclude that serum alkaline DNase activity is influenced by dietary factors as well as surgical trauma. These factors may limit the clinical usefulness of SADA in patients with cancer.

Initial experiences with serum alkaline DNase activity in monitoring the effects of therapy for carcinoma of the uterine cervix

The objective was to evaluate if variations in serum alkaline DNase activity (SADA) can predict the effects of therapy in women with early stages of primary cervical carcinoma. 29 out of 33 patients had no evidence of disease after therapy. Only 5 out of the 29 women showed increased SADA levels after therapy compared with the pretreatment SADA value. Of the 4 women with evidence of disease after therapy, 3 had unchanged or decreased SADA levels. We conclude that serum alkaline DNase activity seems to have little to offer in predicting the effects of treatment in stage I and stage II cervical carcinoma.