Apoptosis of circulating tumor cells in prostate cancer patients.

BACKGROUND: The prescence of circulating tumor cells (CTCs) in the peripheral blood of cancer patients and their frequency has been correlated with disease status. METHODS: In this study, CTCs were characterized by flow cytometry and fluorescence microscopy after immunomagnetic enrichment from 7.5-ml blood samples collected from patients with prostate cancer in evacuated blood-draw tubes that contained an anticoagulant and a preservative. Events were classified as tumor cell candidates if they expressed cytokeratin, lacked CD45, and stained with the nucleic acid dye 4,6-diamidino-2-phenylindole. RESULTS: In the blood of prostate cancer patients, only few of these events were intact cells. Other CTC events appeared as damaged cells or cell fragments by microscopy. By flow cytometry, these events stained variably with 4,6-diamidino-2-phenylindole and frequently expressed the apoptosis-induced, caspase-cleaved cytokeratin 18. Similar patterns of cell disintegration were observed when cells of the prostate line LNCaP were exposed to paclitaxel before spiking the cells into normal blood samples. CONCLUSIONS: The different observed stages of tumor cell degradation or apoptosis varied greatly between patients and were not found in blood of normal donors. Enumeration of CTCs and identification of CTCs undergoing apoptosis may provide relevant information to evaluate the response to therapy in cancer patients.     

Modified differential display technique that eliminates radioactivity and decreases screening time

Several techniques are available that detect variations in gene expression between cellular populations. These include subtractive hybridization (SH), differential colony hybridization (DCH) and mRNA differential display, all based on the analysis of mRNA. The first two techniques, however, are limited because they require large amounts of mRNA for SH or several rounds of screening for DCH. Differential display overcomes both of these limitations. However, the conventional differential display technique is plagued by false positives and is labor intensive. The identification of genes that are truly differentially expressed, therefore, becomes a formidable task. We describe a modified differential display technique that overcomes the limitations of the conventional technique. This new technique eliminates a source of false positives, decreases the time required to screen a set of primers and reduces the use of radioactivity.     

The effect of age on the response of the detrusor to intracellular mechanical stimulus: DNA replication and the cell actin matrix.

Benign prostatic hypertrophy and posterior urethral valves present at both extremes of the age spectrum. Both disease processes can obstruct the urinary stream and ultimately have pathophysiological effects on detrusor structure and function. The mechanisms regulating the structural reorganization of the detrusor to a mechanical outflow obstruction are not known. In an attempt to identify maturational differences in myocyte ultrastructure and consequent effects these might have in modifying the response of the detrusor to mechanical stimulus, we studied differences in dynamic nuclear-cytoskeletal interactions in detrusor tissue in an animal model. Using a drug which specifically severs actin, cytochalasin D (CD), as an intracellular mechanical stimulus, we measured changes in nuclear area and the rate of DNA synthesis in detrusor myocytes from young (2-3 week) and old (8-12 mon) guinea pigs. We found that there were age specific differences to intracellular mechanical stimuli in detrusor muscle. Nuclei of myocytes from young animals showed elastic recoil on severing the cell actin matrix and the tissue from young animals increased replicative DNA synthesis with an intracellular stimulus. In contrast, nuclear shape changes in myocytes from old animals suggested less elasticity, and there was no increase in DNA synthesis with disruption of the cell actin matrix. Anti-alpha-smooth muscle actin antibody and rhodamine phalloidin staining of actin in cytochalasin D treated primary explants of detrusor myocytes showed dose dependent disruption of the actin component of the cytoskeleton. These results suggest that there are fundamental modifications in detrusor myocyte ultrastructure with age. These maturational changes might result in differences in the pathophysiological and structural reorganization of the detrusor in response to outflow obstruction in infancy and adulthood. Furthermore, they suggest that 1) a tensile equilibrium exists between the myocyte nucleus and cytoskeleton; 2) there appears to be a decrease in myocyte nuclear elasticity with ageing; 3) release of nuclear template restrictions increases activity of DNA polymerase alpha in young, but not old, detrusor myocytes; and 4) mechanico-chemical signal transduction in detrusor myocytes may be mediated via the cytoskeleton. In addition, based on previous reports of actin within the nucleus, the results suggest that 1) nuclear actin may have a homeostatic structural role, maintaining the tensile equilibrium between nucleus and cytoskeleton, and 2) integrity of nuclear actin may function to maintain the spatial template restriction on DNA polymerase alpha activity.     

The effect of extracellular matrix interactions on morphologic transformation in vitro

There is emerging evidence that the structure and function of a cell is dependent in part on the contacts that cells make with the extracellular matrix. We report here the effect of extracellular matrices secreted from both normal and tumor cells have on the structure of normal rat kidney epithelial cells. Normal rat kidney cells plated on the basement membrane secreted by tumor cells adopt a morphology and phenotype which closely resembles a Kirsten-ras transformed normal rat kidney cell. This morphologic transformation was not observed for cells plated on individual extracellular matrix components or on basement membrane secreted by normal placenta cells. This suggests that tumor derived basement membrane has unique characteristics which may cause morphologic transformation of normal rat kidney cells.     

Structural organization of the beta-globin locus of B-haplotype sheep

Goats and some sheep synthesize a juvenile hemoglobin, Hb C (alpha 2 beta C2), at birth and produce this hemoglobin exclusively during severe anemia. Sheep that synthesize this juvenile hemoglobin are of the A haplotype. Other sheep, belonging to a separate group, the B haplotype, do not synthesize hemoglobin C and during anemia continue to produce their adult hemoglobin. To understand the basis for this difference we have determined the structural organization of the beta- globin locus of B-type sheep by constructing and isolating overlapping genomic clones. These clones have allowed us to establish the linkage map 5' epsilon I-epsilon II-psi beta I-beta B-epsilon III-epsilon IV- psi beta II-beta F3' in this haplotype. Thus, B sheep lack four genes, including the BC gene, and have only eight genes, compared with the 12 found in the goat globin locus. The goat beta-globin locus is as follows: 5' epsilon I-epsilon II-psi beta X-beta C-epsilon III-epsilon IV-psi beta Z-beta A-epsilon V-epsilon VI-psi beta Y-beta F3'. Southern blot analysis of A-type sheep reveals that these animals have a beta- globin locus similar to that of goat, i.e., 12 globin genes. Thus, the beta-globin locus of B-haplotype sheep resembles that of cows and may have retained the duplicated locus of the ancestor of cows and sheep. Alternatively, the B-sheep locus arrangement may be the result of a deletion of a four-gene set from the triplicated locus.      

Factors affecting the binding of polycyclic aromatic hydrocarbons to human embryo cells, and transformable and non-transformable hamster embryo cells.

The effects of various factors, including population doubling number, percent of confluence, serum concentration and storage in liquid nitrogen on the binding of several polycyclic aromatic hydrocarbons to human and hamster embryo cells were studied. The binding of 7,12-dimethylbenz[a]-anthracene (DMBA) to hamster embryo cells DNA, RNA and protein was maximal after 22 h of treatment. In contrast, binding to human embryo cell macromolecules increased for at least 55 h. Treatment of hamster embryo cells at 100% confluence resulted in much less binding than treatment at 70% confluence, whereas with human embryo cells the binding increased, or remained constant, following treatment at the greater confluence. The transforming frequency of hamster embryo cells decreases with increasing population doubling number. Accordingly, we found that the binding of DMBA to hamster embryo DNA, RNA and protein decreased approximately 100-fold between population doubling numbers 8 and 20. In transformable cell cultures, DMBA was bound to hamster embryo cell DNA to a greater extent than to RNA or protein. The binding of DMBA to nucleic acids was much greater than binding by either dibenz[a,h]anthracene (DB[a,h]A) or dibenz-[a,c]anthracene (DB[a,c]A), both of which had low binding values at all population doubling numbers tested. Therefore, the best correlation of binding with carcinogenicity and transforming activity was observed with DMBA. Storage of hamster embryo cells in liquid nitrogen did not alter their binding characteristics. Binding of all three hydrocarbons to human embryo cell nucleic acids was low during all population doubling numbers studied, while binding to cellular protein increased until population doubling number 70 and then decreased sharply.     

Characterization of normal human embryo cells grown to over 100 population doublings

Summary Normal human embryonic cells were subcultured for over 100 population doublings without modification of the basic medium. The cells were evaluated for growth rate, confluent density, chromosome stability, growth in soft agar, ability to hydrolyze casein and tumorigenicity. The cells possessed the characteristics of normal cells. The batch of serum used to supplement the medium was found to be of primary importance in the long-term growth of this cell culture. Research sponsored by the National Cancer Institute under Contract No. NO1-CO-25423 with Litton Bionetics, Inc.     

Dynamic process of prostate cancer metastasis to bone

Prostate cancer metastasis to the bone occurs at high frequency in patients with advanced disease, causing significant morbidity and mortality. Over a century ago, the "seed and soil" theory was proposed to explain organ-specific patterns of metastases. Today, this theory continues to be relevant as we continue to discover factors involved in the attraction and subsequent growth of prostate cancer cells to the bone. These include the accumulation of genetic changes within cancer cells, the preferential binding of cancer cells to bone marrow endothelial cells, and the release of cancer cell chemoattractants from bone elements. A key mediator throughout this metastatic process is the integrin family of proteins. Alterations in integrin expression and function promote dissociation of cancer cells from the primary tumor mass and migration into the blood stream. Once in circulation, integrins facilitate cancer cell survival through interactions between other cancer cells, platelets, and endothelial cells of the target bone. Furthermore, dynamic changes in integrins and in integrin-associated signal transduction aid in the extravasation of cancer cells into the bone and in expansion to a clinically relevant metastasis. Thus, we will review the critical roles of integrins in the process of prostate cancer bone metastasis, from the escape of cancer cells from the primary tumor, to their survival in the harsh "third microenvironment" of the circulation, and ultimately to their attachment and growth at distant bone sites.     

CCL2, survivin and autophagy: new links with implications in human cancer

Recent data strongly support the idea that the orchestrated interaction between cancer and other cells in the tumor microenvironment is a vital component in the neoplastic process. Thus, tumor cells take advantage of the signaling molecules of the immune system to proliferate, survive, and invade other tissues. CCL2 (Chemokine (C-C motif) ligand 2, Monocyte chemoattractant protein-1 (MCP-1) has been demonstrated to play a significant role in prostate cancer neoplasia and invasion, and is highly expressed in the tumor microenvironment. We recently reported that CCL2 elicits a strong survival advantage in prostate cancer PC3 cells through PI3K/Akt-dependent regulation of autophagy via the mammalian target of rapamycin (mTOR) pathway and importantly, survivin upregulation is essential in this survival mechanism. Autophagy protects cells from nutrient depletion stress, but, paradoxically, excessive autophagy will result in cell death. How these life or death decisions are regulated remains unclear. Here we discuss the function of survivin in the control of autophagy and the interaction between CCL2, survivin and autophagy in the complex program of tumor progression.