1,721,001 research outputs found
Metabolic and mitochondrial remodelling in cisplatin resistance: studies on ovarian cancer cells and derived cytoplasmic hybrids
Full text linkThe onset of resistance to cisplatin still limits its use in the chemotherapy of ovarian cancer and, despite several mechanisms of resistance have been discovered, they are not exhaustive. The aim of this study was to identify which other pathways are exploited by cancer cells to escape cisplatin cytotoxicity, to possibly prevent or overcome the phenomenon with new pharmacological approaches. The increase of anaerobic glycolysis, even in the presence of oxygen (Warburg effect), is the first observation indicating the alteration of energetic metabolism used by tumor cells as a strategy to adapt and grow independently from the availability of the substrate. This evidence suggested us to investigate the hypothesis that a similar metabolic strategy might be of relevance in resistance to cisplatin. Recently it has been shown that only approximately 1% of intracellular platinum is bound to nuclear DNA, while the great majority of the intracellular drug is available to interact with other nucleophilic sites including but not limited to phospholipids, cytosolic, cytoskeletal and membrane proteins, RNA and mitochondrial DNA. mtDNA, unlike nDNA, does not possess efficient repair systems and is therefore more susceptible to the onset of mutations often associated to cancer development, loss of tumor suppressor, activation of oncogenes and mitochondrial dysfunctions often related with an increase of glycolytic activity. Therefore, the aim of this study was to investigate the energetic metabolism and the mitochondrial function of cisplatin-resistant (C13) and sensitive (2008) ovarian cancer cells with different experimental approaches. Results revealed that resistant cells present a significant reduced respiratory chain activity correlated to a lower mitochondrial mass, altered mitochondrial morphology as well as a metabolomic profile typical of a lipogenic phenotype. To investigate the role of mtDNA and nDNA in the mitochondrial and metabolic remodeling of cisplatin-resistant line, cancer cells (2008-C13) were used to generate transmitochondrial hybrids (H2008-HC13). Mitochondrial DNA of parental and hybrid cells was sequenced, showing similar, almost non pathological, polymorphisms. Interestingly, investigating the energetic metabolism and the mitochondrial structure of hybrids, no differences were observed between H2008 and HC13. These data demonstrated that the metabolic reprogramming of C13 cells was not dependent from mtDNA, but was controlled by nuclear factors. Having regard to these data, the activity of some nuclear transcription factors (HIF-1α, and c-Myc) involved in the metabolic reprogramming of tumor cells, has been evaluated and it has been highlighted a different expression of some of their target genes involved in the glycolytic flux. Finally, the metabolic profile of 2008-C13 cells has been outlined by LC-MS which evidenced some interesting differences in aminoacids, phospholipids and antioxidants content
Effect of Quercetin on Cell Cycle and Cyclin Expression in Ovarian Carcinoma and Osteosarcoma Cell Lines
Full text linkResistance to chemotherapeutic drugs is a major problem in cancer treatment. The search for new interventions able to overcome this resistance may involve compounds of natural origin, such as flavonoids, ubiquitously present in many foods. In the present study, the cytotoxic effects and cell cycle modulation of the flavonoid quercetin were investigated in ovarian carcinoma (SKOV3) and osteosarcoma (U2OS) human cell lines and in their cisplatin (CDDP)-resistant counterparts (SKOV3/CDDP and U2OSPt cells, respectively). Quercetin (10-50 μM) caused evident changes in the distribution of cell cycle phases in the CDDP-resistant SKOV3/CDDP ovarian cell line. The levels of cyclin D1 and cyclin B1 were determined by means of Western blot in all cell lines incubated with quercetin (50 μM) for 48 hours. The cyclin D1 expression was significantly decreased following the treatment with quercetin in SKOV3 and U2OSPt cells, but not in SKOV3/CDDP and U2OS cells. The reduction of cyclin D1 level could be linked to the G1/S phase alteration found in quercetin-treated cells. Although cyclin B1 is required for G2/M phase, and despite our observation that quercetin influenced the G2/M phase of cell cycle, the flavonoid did not affect cyclin B1 levels in all cell lines, indicating the involvement of other possible mechanisms. These results suggest that quercetin, exceeding the resistance to CDDP, might become an interesting tool to evaluate cytotoxic activity in combination with chemotherapy drugs
Antioxidant and anti-inflammatory activities of Cannabis Sativa in epithelial intestinal cell
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Cell cycle control by natural phenols in cisplatin-resistant cell lines.
No full textFifteen plant polyphenols, including flavonoids, cinnamic acids, coumarins and capsaicin, were investigated for their capacity to suppress cell growth and regulate the cell cycle of in vitro human ovarian carcinoma (2008 cell line) and cervix squamous carcinoma cells (A431), and their cisplatin (CDDP)-resistant subclones (C13 and A431Pt, respectively). Evaluation of the cytotoxic effects of the polyphenols (0.01-100 ??M) indicated that especially rhein and quercetin were almost equiactive in wild type and CDDP-resistant cells, indicating lack of cross-resistance with cisplatin. Capsaicin was more potent in CDDP-resistant subclones than in wild type cells. The order of their potencies is flavonoids > anthraquinones > vanilloids > coumarins > phenols, cinnamic acids. The natural phenols which were most cytotoxic (rhein, quercetin and capsaicin) were able to cause the arrest of the cancer cell cycle, suggesting that specific cell cycle regulatory proteins are possibly involved in their intracellular mechanism of action. In particular, the natural compounds were revealed to be more active in CDDP-resistant cells than in wild types, especially inducing apoptotic death
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Effects of genistein on Leber’s hereditary optic neuropathy (LHON) mitochondrial metabolism.
No full textLeber's hereditary optic neuropathy (LHON), a maternally inherited form of central vision loss, is caused by pathogenic point mutations in mitochondrial-encoded subunits of complex I, the first site of the mitochondrial respiratory chain. The most frequent LHON-associated mutations are the homoplasmic m. 11778 G>A in MTND4 gene, the m. 14484 T>C in MTND6 and the m.3460 G>A in ND1 gene [1-2].
One of the open problems in LHON is the variable penetrance: mtDNA mutations are necessary but not sufficient to induce the clinical phenotype. In fact, approximately 50% of males and only 10% of females harboring a primary mtDNA mutation develop the disease. Proposed modifiers include, secondary mtDNA mutations, mtDNA haplogroup, nuclear encoded genes, tobacco and alcohol consumption, and the exposure to toxic compounds [3-4].
By using the cell model of trans-mitochondrial cybrids we recently showed that estrogens ameliorate mitochondrial function, increase cell viability and prevent oxidative stress damage in LHON [5]. Thus, different exposure to estrogens between males and females may account for the still unexplained male prevalence.
Aim of the present study was to compare the anti-oxidative effects of estrogens and phytoestrogens (i.e genistein, one of the soy isoflavones) on LHON metabolism by using the cybrid cells model.
Cybrids were incubated in glucose-free, galactose supplemented medium, forcing the cells to rely mainly on the mitochondrial respiratory chain to produce ATP. Results show that, contrary to control cybrids, in each cell line harboring one of the three most frequent LHON pathogenic mutations, ROS increase, mitochondrial network is altered and there is an high percentage of cell death. Genistein (0.1 μM), similar to estrogens, prevents the alterations induced by galactose on cell growth, ROS production and mitochondrial network. Furthermore genistein activates ERK1 and ERK2 MAP kinases thus up-regulating Mn-SOD antioxidant enzyme. The effects of genistein are antagonised by ERs specific inhibitor (ICI 182780), demonstrating the involvement of estrogen-receptors as mechanism of protection of LHON cybrids from oxidative stress.
Our results open new therapeutic approaches for LHON.
1. Carelli V et al. (2004) - Prog Retin Eye Res, 23: 53–89.
2. Man PY et al. (2009) - J Med Genet, 46: 145–58.
3. Phasukkijwatana N et al. (2010) - Hum Genet 2010, 128: 39–49.
4. Kirkman MA et al. (2009) - Brain, 132: 2317–26.
5. Giordano C, Montopoli M et al. (2011) – Brain, 134:220-34
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