A Preliminary Study of the Effect of Quercetin on Cytotoxicity, Apoptosis, and Stress Responses in Glioblastoma Cell Lines.

A growing body of evidence indicates that dietary polyphenols show protective effects against various cancers. However, little is known yet about their activity in brain tumors. Here we investigated the interaction of dietary flavonoid quercetin (QCT) with the human glioblastoma A172 and LBC3 cell lines. We demonstrated that QCT evoked cytotoxic effect in both tested cell lines. Microscopic observations, Annexin V-FITC/PI staining, and elevated expression and activity of caspase 3/7 showed that QCT caused predominantly apoptotic death of A172 cells. Further analyses confirmed enhanced ROS generation, deregulated expression of SOD1 and SOD2, depletion of ATP levels, and an overexpression of CHOP, suggesting the activation of oxidative stress and ER stress upon QCT exposure. Finally, elevated expression and activity of caspase 9, indicative of a mitochondrial pathway of apoptosis, was detected. Conversely, in LBC3 cells the pro-apoptotic effect was observed only after 24 h incubation with QCT, and a shift towards necrotic cell death was observed after 48 h of treatment. Altogether, our data indicate that exposure to QCT evoked cell death via activation of intrinsic pathway of apoptosis in A172 cells. These findings suggest that QCT is worth further investigation as a potential pharmacological agent in therapy of brain tumors.

Silica nanoparticle-induced oxidative stress and mitochondrial damage is followed by activation of intrinsic apoptosis pathway in glioblastoma cells.

INTRODUCTION: Recently, the focus of oncological research has been on the optimization of therapeutic strategies targeted at malignant diseases. Nanomedicine utilizing silicon dioxide nanoparticles (SiNPs) is one such strategy and is rapidly developing as a promising tool for cancer diagnosis, imaging, and treatment. Nevertheless, little is known about the mechanisms of action of SiNPs in brain tumors. MATERIALS AND METHODS: Here, we explored the effects of 5-15 nm SiNPs in the human glioblastoma cell line LN229. In this respect, MTT assays, microscopic observations, flow cytometry analyses, and luminescent assays were performed. Moreover, RT-qPCR and Western blot analyses were done to determine gene and protein expressions. RESULTS: We demonstrated that SiNPs triggered evident cytotoxicity, with microscopic observations of the nuclei, annexin V-fluorescein isothiocyanate/propidium iodide staining, and elevated caspase 3/7 activity, suggesting that SiNPs predominantly induced apoptotic death in LN229 cells. We further showed the occurrence of oxidative stress induced by enhanced reactive oxygen-species generation. This effect was followed by deregulated expression of genes encoding the antioxidant enzymes SOD1, SOD2, and CAT, and impaired mitochondria function. SiNP- induced mitochondrial dysfunction was characterized by membrane-potential collapse, ATP depletion, elevated expression of BAX, PUMA, and NOXA with simultaneous downregulation of BCL2/BCL2L1, and activation of caspase 9. Moreover, RT-qPCR and Western blot analyses demonstrated increased levels of the endoplasmic reticulum stress markers GRP78, GRP94, and DDIT3, as well as strongly increased expressions of the IL1B and COX2 genes, suggesting activation of endoplasmic reticulum stress and a proinflammatory response. CONCLUSIONS: Altogether, our data indicate that in LN229 cells, SiNPs evoke cell death via activation of the intrinsic apoptosis pathway and suggest that other aspects of cellular function may also be affected. As such, SiNPs represent a potentially promising agent for facilitating further progress in brain cancer therapy. However, further exploration of SiNP long-term toxicity and molecular effects is necessary prior to their widespread application.

Molecular and cellular effects of a novel hydroxamate-based HDAC inhibitor - belinostat - in glioblastoma cell lines: a preliminary report.

Histone deacetylase (HDAC) inhibitors are now intensively investigated as potential cytostatic agents in many malignancies. Here, we provide novel information concerning the influence of belinostat (Bel), a hydroxamate-based pan-HDAC inhibitor, on glioblastoma LN-229 and LN-18 cells. We found that LN-229 cells stimulated with 2 µmol/L of Bel for 48 h resulted in 70 % apoptosis, while equivalent treatment of LN-18 cells resulted in only 28 % apoptosis. In LN-229 cells this effect was followed by up-regulation of pro-apoptotic genes including Puma, Bim, Chop and p21. In treated LN-18 cells only p21 was markedly overexpressed. Simultaneously, LN-229 cells treated with 2 µmol/L of Bel for 48 h exhibited down-regulation of molecular chaperones GRP78 and GRP94 at the protein level. In contrast, in LN-18 cells Western blot analysis did not show any marked changes in GRP78 nor GRP94 expression. Despite noticeable overexpression of p21, there were no signs of evident G1 nor G2/M cell cycle arrest, however, the reduction in number of the S phase cells was observed in both cell lines. These results collectively suggest that Bel can be considered as potential anti-glioblastoma agent. To our knowledge this is the first report presenting the effects of belinostat treatment in glioblastoma cell lines.

Low glucose dependent decrease of apoptosis and induction of autophagy in breast cancer MCF-7 cells.

Cancer cells have developed a number of adaptation mechanisms involving the signal activation of the transduction pathways, which promotes the progression and metastasis. Our results showed that the percentage of apoptotic MCF-7 cells incubated in the low glucose medium for 48 h was lower in comparison to those cultured in the high glucose medium, despite the high expression of the proapoptotic transcription factor-CHOP. Furthermore, the MCF-7 cells incubated in the low glucose medium for 48 h showed a higher expression of NF-κB p100/p52 subunits compared to cells incubated in the high glucose medium. Moreover, our findings demonstrated that the shortage of glucose strongly induces autophagy in MCF-7 cells. The activation of this process is not associated with the changes in the expression of mTOR kinase. We suggest, that the antiapoptotic chaperone ORP150 induction, transcription factor NF-κB2 activation, and increased autophagy constitute mechanisms protecting the MCF-7 cells against apoptosis.

Efficient apoptosis and necrosis induction by proteasome inhibitor: bortezomib in the DLD-1 human colon cancer cell line.

The inhibition of the 26S proteasome evokes endoplasmic reticulum stress, which has been shown to be implicated in the antitumoral effects of proteasome inhibitors. The cellular and molecular effects of the proteasome inhibitor-bortezomib-on human colon cancer cells are as yet poorly characterized. Bortezomib selectively induces apoptosis in some cancer cells. However, the nature of its selectivity remains unknown. Previously, we demonstrated that, in contrast to normal fibroblasts, bortezomib treatment evoked strong effect on apoptosis of breast cancer cells incubated in hypoxic and normoxic conditions. The study presented here provides novel information on the cellular effects of bortezomib in DLD-1 colon cancer cells line. We observe twofold higher percentage of apoptotic cells incubated for 48 h with 25 and 50 nmol/l of bortezomib in hypoxic conditions and four-, fivefold increase in normoxic conditions in comparison to control cells, incubated without bortezomib. It is of interest that bortezomib evokes strong effect on necrosis of DLD-1 colon cancer cell line. We observe the sixfold increase in necrosis of DLD-1 cells incubated with 25 or 50 nmol/l of bortezomib for 48 h in hypoxia and fourfold increase in normoxic conditions in comparison to adequate controls. We suggest that bortezomib may be candidates for further evaluation as chemotherapeutic agents for human colon cancer.

Low-glucose medium induces ORP150 expression and exerts inhibitory effect on apoptosis and senescence of human breast MCF7 cells.

Glucose deprivation is a factor evoking endoplasmic reticulum (ER) stress and induction of expression of an oxygen-regulated protein of 150 kDa (ORP150). We studied the effect of inducible overexpression of ORP150 on senescence and apoptosis of human breast carcinoma cells (MCF7) and human skin fibroblasts. We found an inhibitory effect of ORP150 on apoptosis and senescence of MCF7 cells, but not fibroblasts in ER stress conditions. An increased expression of senescence-associated ß-galactosidase and acid ß-galactosidase activity (biomarkers of cellular senescence) was observed. We suggest that ORP150 induction in cancer cells can promote tumour progression and may be a major cause of their resistance to chemotherapeutics.

Lysosomal exoglycosidases in serum and urine of patients with pancreatic adenocarcinoma.

Lysosomal exoglycosidases: N-acetyl-ß-D-hexosaminidase (HEX), ß-D-galactosidase (GAL), α-L-fucosidase (FUC) and α-D-mannosidase (MAN) modify oligosaccharide chains of glycoconjugates in endoplasmatic reticulum and/or Golgi apparatus and degrade them in lysosomes. In acid environment of lysosome, exoglycosidases degrade oligosaccharide chains of glycoproteins, glycolipids and glycosaminoglycans by eliminating single sugars from the edges of oligosaccharide chains. Neoplasms change biochemical processes in tissues and may significantly change the activity of many enzymes including the activity of lysosomal exoglycosidasses in serum and urine of persons with neoplasmatic diseases. The aim of the present paper was evaluation the activity of HEX, GAL, FUC and MAN in serum and urine of patients with pancreatic adenocarcinoma. Serum and urine samples were collected from 15 patients with adenocarcinoma of the pancreas and 15 healthy persons. The activity of lysosomal exoglycosidases was determined by the method of Marciniak et al. adapted to serum and urine of patients with adenocarcinoma of the pancreas. Our results indicate significant decrease in activity of GAL (p=0.037) in serum of patients with pancreatic adenocarcinoma, significant increase in activity of HEX (p<0.001) and FUC (p=0.027) in serum, and HEX (p=0.003) in urine, as well as significant decrease of FUC (p=0.016) and MAN (p=0.029) in urine o patients with adenocarcinoma of the pancreas, in comparison to the control group. Increase in activity of some lysosomal enzymes in serum and urine of pancreatic adenocarcinoma patients, may indicate on destruction of pancreatic tissue by pancreatic adenocarcinoma. Determination of the HEX, GAL, FUC and MAN in serum and urine may be useful in diagnostics of pancreatic adenocarcinoma.

Urinary fructose-1,6-bisphosphatase activity as a marker of the damage to the renal proximal tubules in children with idiopathic nephrotic syndrome.

BACKGROUND: Disturbances in the function of renal proximal tubules increase the activity of several enzymes in urine. Among them is fructose-1,6-bisphosphatase (FBP-1), the key enzyme of gluconeogenesis normally present in the renal convoluted, and to smaller degree, proximal renal tubular cells cytosol. FBP-1 activity in urine and serum was used for evaluation of the degree of graft ischemia during human kidney transplantation. The aim of our present research was to determine FBP-1 activity in urine as an indicator of damage to renal proximal tubules in children with idiopathic nephrotic syndrome (INS). METHODS: We evaluated the excretion of FBP-1 into urine of 21 children (10 girls and 11 boys) with INS, aged from 10 to 15 years and 30 healthy children (14 girls and 16 boys), aged from 2 to 15 years. FBP-1 activity was determined by the Latzko and Gibbs method. Creatinine (mg%) in urine and blood serum was measured by the Jaffe method in Larsen modification. Protein in blood serum was determined by the biuret method (g/L), and albumin (mg%) by the Young method. Proteinuria in the urine collected over 24 h was measured with the Exton turbidimetric method by Tomaszewski with modification and expressed in mg/kg body weight/24 h. RESULTS: In the urine of 30 healthy children, FBP-1 activity was in the range from 0-1.74 micromol FPB/h/mmol of creatinine. In 43% of the healthy children, FBP-1 activity in urine was not detectable. In the period of intensive proteinuria during the INS in children, FBP-1 activity and protein concentrations in urine were significantly higher than in the control group (p<0.0008 and p<0.0001, respectively). In the urine of children with active INS, we observed a very weak negative linear correlation between protein concentration and FBP-1 activity (r=-0.5018, p=0.067). After treatment with Encorton (prednisone), FBP-1 activity and protein concentration in urine dropped to values of the control group. CONCLUSIONS: "The overload" of proximal renal tubules by proteins in children with INS releases FBP-1 into urine. FBP-1 activity in urine may therefore be considered as a marker of damage to the proximal renal tubules in children with INS.