Autoschizis of human ovarian carcinoma cells: scanning electron and light microscopy of a new cell death induced by sodium ascorbate: menadione treatment

Glioma progression and recurrence involving maintenance and expansion strategies of glioma stem cells by organizing self-advantageous niche microenvironments

Due to the nature of enhanced resistance to conventional chemo/radiotherapies and metastasis, highly tumorigenic cancer stem cells (CSCs) have been proposed as a promising target for cancer eradication. To tackle the therapeutic difficulties of cancers involving CSCs, extensive research efforts have been directed toward understanding the extracellular microenvironments of CSCs, i.e., CSC niche, which plays important roles in CSC maintenance and expansion. Here we review recently identified mechanisms of maintenance and expansion of glioma CSCs (GSCs) leading to glioma progression and recurrence, with particular emphasis on the reports made by studies with a unique approach using polymer microarrays screening and with a unique viewpoint of necrotic particles. The polymer-based approach identified two groups of niche components, extracellular matrices (ECMs) and iron, and uncovered that co-expression of ECM-, iron-, and macrophage-related genes is predictive of glioma patients' outcome. The study in view of a unique fraction of GSC-derived necrotic particles proposed that such particles develop GSC-supportive tumor-associated macrophages (TAMs). Taken together, these studies provide new insights into the mechanisms underlying GSC-driven niche development, i.e., organization of the self-advantageous niche microenvironments for GSC maintenance and expansion leading to glioma progression and recurrence. A series of such studies can redefine the current concept of anti-GSC niche therapy that targets ligands/receptors supporting GSCs, and have potential to accelerate cancer therapy development.

Comparison of ultrastructural changes and the anticarcinogenic effects of thymol and carvacrol on ovarian cancer cells: which is more effective?

Ovarian cancer is the seventh most common cancer worldwide in women. Many anticancer drugs are currently used clinically have been isolated from plant species or are based on such substances. Thymol (5-methyl-2-isopropylphenol) and carvacrol are oxygenated aromatic compounds from the monoterpene group. They are the main constituents of thyme essential oil and show antiproliferative, antioxidant, and antiseptic properties. The aim of this study is to compare the antiproliferative and apoptotic effects of thymol and carvacrol on SKOV-3 ovarian cancer cell line. The cancer cells were treated with different concentrations of thymol and carvacrol (100, 200, 400, 600 µM) at 24 h and 48 h durations. The cell viability was investigated by MTT assay and analysis of apoptosis with annexin V assay was determined. The study show that thymol and carvacrol significantly induced apoptosis in all groups as dose and time-dependent (p < .05). The data in the present study demonstrated that thymol and carvacrol have apoptotic and antiproliferative properties in a concentration-dependent manner toward ovarian cancer cells. SKOV-3 cancer cell line was much more sensitive to the toxic effect of thymol than carvacrol.

Downregulation of HNF1 homeobox B is associated with drug resistance in ovarian cancer

The expression of HNF1 homeobox B (HNF1B) is associated with cancer risk in several tumors, including ovarian cancer, and its decreased expression play roles in cancer development. However, the study of HNF1B and cancer is limited, and its association with drug resistance in cancer has never been reported. On the basis of array data retrieved from Oncomine and Gene Expression Omnibus (GEO) online database, we found that the mRNA expression of HNF1B in 586 ovarian serous cystadenocarcinomas and in platinum-resistant A2780 epithelial ovarian cancer cells was significantly decreased, indicating a potential role of HNF1B in drug resistance in ovarian cancer. Based on this finding, comprehensive bioinformatics analyses, including protein/gene interaction, protein-small molecule/chemical interaction, biological process annotation, gene co-occurrence and pathway enrichment analysis and microRNA-mRNA interaction, were performed to illustrate the association of HNF1B with drug resistance in ovarian cancer. We found that among the proteins/genes, small molecules/chemicals and microRNAs which directly interacted with HNF1B, the majority was associated with drug resistance in cancer, particularly in ovarian cancer. Biological process annotation revealed that HNF1B closely related to 24 biological processes which were all notably associated with ovarian cancer and drug resistance. These results indicated that the downregulation of HNF1B may contribute to drug resistance in ovarian cancer, via its direct interactions with these drug resistance-related proteins/genes, small molecules/chemicals and microRNAs, and via its regulations on the drug resistance-related biological processes. Pathway enrichment analysis of 36 genes which co-occurred with HNF1B, ovarian cancer and drug resistance indicated that the HNF1B may perform its drug resistance-related functions through 4 pathways including ErbB signaling, focal adhesion, apoptosis and p53 signaling. Collectively, in this study, we illustrated for the first time that HNF1B may contribute to drug resistance in ovarian cancer, potentially through the 4 pathways. The present study may pave the way for further investigation of the drug resistance-related functions of HNF1B in ovarian cancer.

Synergistic antitumor cytotoxic actions of ascorbate and menadione on human prostate (DU145) cancer cells in vitro: nucleus and other injuries preceding cell death by autoschizis

Scanning (SEM) and transmission electron microscopy (TEM) were used to characterize the cytotoxic effects of ascorbate (VC), menadione (VK3), or a VC:VK3 combination on a human prostate carcinoma cell line (DU145) following a 1-h vitamin treatment and a subsequent 24-h incubation in culture medium. Cell alterations examined by light and electron microscopy were treatment-dependent with VC + VK3 >VK3 > VC > Sham. Oxidative stress-induced damage was found in most organelles. This report describes injuries in the tumor cell nucleus (chromatin and nucleolus), mitochondria, endomembranes, lysosomal bodies (autophagocytoses) and inclusions. Morphologic alterations suggest that cytoskeleton damage is likely responsible for the superficial cytoplasmic changes, including major changes in cell shape and size and the self-excising phenomena. Unlike apoptotic bodies, the excised pieces contain ribonucleoproteins, but not organelles. These deleterious events cause a progressive, significant reduction in the tumor cell size. During nuclear alterations, the nuclei maintain their envelope during chromatolysis and karyolysis until cell death, while nucleoli undergo a characteristic segregation of their components. In addition, changes in fat and glycogen storage are consistent the cytotoxic and metabolic alterations caused by the respective treatments. All cellular ultrastructural changes are consistent with cell death by autoschizis and not apoptosis or other kinds of cell death.

Bacterial survival strategies suggest rethinking cancer cooperativity

Despite decades of a much improved understanding of cancer biology, we are still baffled by questions regarding the deadliest traits of malignancy: metastatic colonization, dormancy and relapse, and the rapid evolution of multiple drug and immune resistance. New ideas are needed to resolve these critical issues. Relying on finding and demonstrating parallels between collective behavior capabilities of cancer cells and that of bacteria, we suggest communal behaviors of bacteria as a valuable model system for new perspectives and research directions. Understanding the ways in which bacteria thrive in competitive habitats and their cooperative strategies for surviving extreme stress can shed light on cooperativity in tumorigenesis and portray tumors as societies of smart communicating cells. This may translate into progress in fathoming cancer pathogenesis. We outline new experiments to test the cancer cooperativity hypothesis and reason that cancer may be outsmarted through its own 'social intelligence'.

Nucleolar changes and fibrillarin redistribution following apatone treatment of human bladder carcinoma cells

Ascorbate and menadione (Apatone) in a ratio of 100:1 kills tumor cells by autoschizis. In this study, vitamin-induced changes in nucleolar structure were evaluated as markers of autoschizis. Human bladder carcinoma (T24) cells were overlain with vitamins or with culture medium. Supernatants were removed at 1-hr intervals from 1 to 4 hr, and the cells were washed with PBS and prepared for assay. Apatone produced marked alterations in nucleolar structure including redistribution of nucleolar components, formation of ring-shaped nucleoli, condensation and increase of the proportion of perinucleolar chromatin, and the enlargement of nucleolar fibrillar centers. Immunogold labeling of the nucleolar rRNA revealed a granular localization in treated and sham-treated cells, and immunogold labeling of the rDNA revealed a shift from the fibrillar centers to the condensed perinucleolar chromatin. Fibrillarin staining shifted from the fibrillar centers and adjacent regions to a more homogeneous staining of the entire nucleolus and was consistent with the percentage of autoschizic cells detected by flow cytometry. Because autoschizis entails sequential reactivation of DNase I and DNase II, and because the fibrillarin redistribution following DNase I and Apatone treatment is identical, it appears that the nucleolar and fibrillarin changes are markers of autoschizis.

Autoschizis of T-cells is induced by the nutritional supplement, Cr(III)picolinate

In recent times, Cr(III)(picolinate)(3) [Cr(III)(pic)(3)] a nutritional supplement, is gaining attention because of its clastogenic and mutagenic properties. Earlier studies of ours indicated that Cr(III)(pic)(3) is cytotoxic to lymphocytes with ROS and mitochondrial events playing a role in bringing about apoptosis. Now, we report that, autoschizis is induced in lymphocytes in a concentration and time dependent manner which is confirmed through TEM and SEM. Lymphocytes treated with concentrations of 100microM of Cr(III)(pic)(3) exhibit features such as cytoplasmic bleb, self excision of cytoplasm, cytoplasmic leakage and membrane bound bodies formed from the excised pieces apart from apoptosis and necrosis. Though autoschizis has been described in tumor cell lines treated with menadione and ascorbate, occurrence of this cell death in normal T-lymphocytes is reported here. The cellular events that accompany autoschizis are found to be increase in intracellular Reactive Oxygen Species (ROS) and cytoplasmic lactate dehydrogenase, loss of mitochondrial membrane potential (MMP) and depletion of ATP. Further, autoschizis is effected through increases in DNase I and DNase II activity with a concomitant decrease in caspase-3 activity which leads to a random cleavage of the DNA as demonstrated by a smear like pattern after electrophoresis on agarose gel.

Cell Death by Autoschizis in TRAMP Prostate Carcinoma Cells as a Result of Treatment by Ascorbate: Menadione Combination

A prostate carcinoma cell line derived from the transgenic murine prostate cancer model (TRAMP) was treated with ascorbate (VC) alone, menadione (VK(3)) alone, or a combination of ascorbate:menadione (VC + VK(3)) for 1, 2, and 4 h. Cytotoxic cell alterations examined by light and electron microscopy were treatment-dependent with VC + VK(3) > VC > VK(3). Induced by oxidative stress, these alterations included cytokeletal changes conducive to cytoplasmic blebbing, self-excisions, and progressive nuclear alterations. While the excised parts contained ribosomes, they were devoid of nuclear fragments or other organelles. The organelle-free self-excisions caused an extreme reduction in cell size as well as chromatolysis and karyolysis that were consistent with cell death by autoschizis, but not with apoptosis.

Morphology and DNA degeneration during autoschizic cell death in bladder carcinoma T24 cells induced by ascorbate and menadione treatment

Feulgen and actin-phalloidin staining as well as gel electrophoresis have been employed in conjunction with cell ultrastructure to describe the effects of 1-, 2-, and 4-hr ascorbate (VC), menadione (VK(3)), and ascorbate:menadione (VC:VK(3)) treatments on the T24 human bladder carcinoma cell line. T24 cells exposed to VC alone display blebs and other superficial membrane defects related to membrane alterations and to superficial cytoskeleton changes. VK(3) treatment damages the cell nucleus and organelles, leads to the redistribution of the organelles in the perikaryon as a consequence of cytoskeletal damage, and results in cytoplasmic self-excisions. After VC:VK(3) treatment, the cells show exaggerated alterations characteristic of each vitamin treatment alone, including damaged mitochondria, self-excision of organelle-free pieces of cytoplasm, and extrusion of the perikaryon containing a nucleus surrounded by the damaged organelles. The nuclear envelope appears intact and contains chromatin that decondenses and dissipates. During the cellular demise that concludes with apparent karyolysis, the cells significantly decrease their size and alter their shape. However, the cisterns of rough endoplasmic reticulum are undamaged, but may become dilated. Since the cellular phenomena leading to cell death differ morphologically from apoptosis and necrosis, but entail self-cutting without nuclear bodies, this new form of cell death was called autoschizis. In addition, gel electrophoresis and Feulgen staining demonstrate that autoschizis is accompanied by random DNA degeneration.

Autoschizis: a new form of cell death for human ovarian carcinoma cells following ascorbate:menadione treatment. Nuclear and DNA degradation

Microscopic aspects, densitometric evaluation of Feulgen-stained DNA, and gel electrophoresis of total DNA have been used to elucidate the effects of 1, 2, and 3 h VC (ascorbic acid), VK3 (menadione), and combined VC:VK3 treatments on the cellular and nuclear morphology and DNA content of a human ovarian carcinoma cell line (MDAH 2774). Optical densitometry showed a significant decrease in cancer cell DNA content directly related to VC and VC:VK3 treatments while VK3 and VC:VK3 treated cells exhibited cytoskeletal changes that included self-excision of cytoplasmic pieces with no membranous organelles. Nuclei decreased in size and exhibited poor contrast consistent with progressive decondensation of their chromatin. Degraded chromatin was also detected in cytoplasmic autophagosomes. Nucleoli segregated their components and fragmented into small pieces. Gel electrophoretic analysis of total DNA revealed evidence of generalized DNA degradation specific to treated tumor cells. These results are consistent with previous observations [Scanning 20 (1998a) 564; Ultrastruct. Pathol. 25 (2001b) 183; J. Histochem. Cytochem. 49 (2001) 109] which demonstrated that the VC:VK3 combination induced autoschizic cell death by a series of cytoplasmic excisions without organelles along with specific nuclear ultrastructural damage.