Barbara Szachowicz-Petelska

Changes in electric charge and phospholipids composition in human colorectal cancer cells

Cancer cells perform their malicious activities through own cell membranes that screen and transmit inhibitory and stimulatory signals out of the cells and into them. This work is focused on changes of phospholipids content (PI—phosphatidylinositol, PS—phosphatidylserine, PE—phosphatidylethanolamine, PC—phosphatidylcholine) and electric charge that occur in cell membranes of colorectal cancer of pT3 stage, various grades (G2, G3) and without/with metastasis. Qualitative and quantitative composition of phospholipids in the membrane was determined by HPLC (high-performance liquid chromatography). The surface charge density of colorectal cancer cell membranes was measured using electrophoresis. The measurements were carried out at various pH of solution. It was shown that the process of cancer transformation was accompanied by an increase in total amount of phospholipids as well as an increase in total positive charge at low pH and total negative charge at high pH. A malignant neoplasm cells with metastases are characterized by a higher PC/PE ratio than malignant neoplasm cells without metastases. (Mol Cell Biochem 276: 113–119, 2005)

Altered membrane free unsaturated fatty acid composition in human colorectal cancer tissue

Polyunsaturated free fatty acids (PUFAs) participate in normal functioning of the cell, particularly in control intracellular cell signalling. As nutritional components they compose a human diet with an indirect promoting influence on tumourogenesis. The PUFAs level depends on the functional state of the membrane. This work is focused on changes only of free unsaturated fatty acids amount (AA – arachidonic acid, LA – linoleic acid, ALA – α-linolenic acid, palmitoleic acid (PA) and oleic acid) in cell membranes of colorectal cancer of pT3 stage, G2 grade without metastasis. Qualitative and quantitative composition of free unsaturated fatty acids in the membrane was determined by high-performance liquid chromatography. It was shown that the malignant transformation was accompanied by a decrease in amount of LA and ALA while arachidonic and oleic acids increased. It is of interest that free AA levels are elevated in colon cancer, as AA is the precursor to biologically active eicosanoids.

Characterization of the Cell Membrane During Cancer Transformation

The electric properties of the plasma membrane is an indicator of cell condition. The simple, and highly effective, normal-phase (NP) and reversed-phase (RP) high-performance liquid chromatography (HPLC) methods assess phospholipid and free unsaturated fatty acid content, respectively. Herein we focus on changes in phospholipid content (phosphatidylinositol (PI), phosphatidylserine (PS), phosphatidylethanoloamine (PE), phosphatidylcholine (PC)) and free unsaturated fatty acid content (arachidonic acid (AA), linoleic acid (LA), α-linolenic acid (ALA), palmitoleic acid (PA)) in the plasma membranes of non-metastatic colorectal cancer cells (pT3 stage, G2 grade). Surface charge density of normal and tumor large intestine tissue was measured by electrophoresis. The surface charge density as a function of pH, acidic (C TA ) and basic (C TB- ) functional group concentrations and their average association constants with hydrogen (K AH ) or hydroxyl (K BOH- ) ions were evaluated. Cancer transformation was accompanied by an increase in total phospholipids as well as and increase in C TA , C TB and K BOH whereas the content of free fatty acids and K AH decreased compared with unchanged tumor cells.

Changes in physico-chemical properties of human large intestine tumour cells membrane.

Tumour cells produce and excrete to blood many substances which are present in the cell itself in trace amounts only. Our work has been aimed at the determination of changes in electric charge and in phospholipid composition of large intestine normal mucosa and colorectal cancer cells.Surface charge density of tumour unaffected mucosa and of tissue sections from tumours, was measured by electrophoresis. The measurements were carried out at various pH of solution. Membrane isoelectric point was determined by measuring its electric charge in function of pH as well as total positive charge at low pH and total negative charge at high pH. Qualitative and quantitative composition of phospholipids in the membrane was determined by HPLC. Four phospholipid classes were identified: PI, PS, PE and PC and their surface concentrations were determined.The electric charge calculated from phospholipid concentrations is by three orders of magnitude higher than that determined electrophoretically. It indicates that the groups present in the membrane surface are involved in equilibria in which the charge is neutralized.The electric charge calculated from phospholipid concentrations is by three orders of magnitude higher than that determined electrophoretically. It indicates that the groups present in the membrane surface are involved in equilibria in which the charge is neutralized.Tumour changes provoke an increase in surface charge density of large intestine membrane, whereas the content of individual phospholipids increased or decreased depending on a patient.

Phospholipid Composition and Electric Charge in Healthy and Cancerous Parts of Human Kidneys

Phospholipids are ubiquitous in nature and are essential for the lipid bilayer of cell membranes. Their structural and functional properties are pivotal for the survival of the cell. In this study the phospholipids of healthy and cancerous human renal tissues from the same patients are compared with special reference to the electric charge of the membrane. A simple and highly effective normal-phase method is described for analyzing phospholipids content. This work is focused on changes of phospholipids content (PtdIns, phosphatidylinositol; PtdSer, phosphatidylserine; PtdEtn, phosphatidylethanoloamine; PtdCho, phosphatidylcholine) in cell membranes of renal cancer of pT1 stage, G2 grade, without metastasis. Surface charge density of healthy and cancerous human renal tissues was measured by electrophoresis. The measurements were carried out at various pH of solution. Depending on the surface charge density as a function of pH, acidic (CTA) and basic (CTB) functional group concentrations and their average association constants with hydrogen (KAH) or hydroxyl (KBOH) ions were evaluated. The process of cancer transformation was accompanied by an increase in total amount of phospholipids as well as an increase in CTA and KBOH, whereas KAH and CTB were decreased compared with unchanged tumor cells.

Effect of L-carnitine on liver cell membranes in ethanol-intoxicated rats.

Ethanol intoxication is characterized by changes in cell metabolism which alter the structure and function of cell membrane components, including phospholipids and integral membrane proteins. The interaction of food nutrients with ethanol may modulate alcohol toxicity. One such compound is l-carnitine (l-3-hydroxy-4-N,N,N-trimethylaminobutyrate), which is also an antioxidant. Here we investigate l-carnitine as an antioxidant and assess its effect on the composition and electrical charge of liver cell membranes in ethanol-intoxicated rats. Qualitative and quantitative phospholipid composition and the presence of integral membrane proteins were determined by high performance liquid chromatography (HPLC). Electrophoresis was used to determine the surface charge density of the rat liver cell membranes. Ethanol increased phospholipid levels and altered the level of integral proteins as determined by decreased phenylalanine (Phe), cysteine (Cys) and lysine (Lys). Ethanol significantly enhanced changes in the surface charge density of the liver cell membranes. l-Carnitine administration to ethanol-intoxicated rats significantly protects phospholipids and proteins against oxidative modifications. Therefore, the beneficial effect of l-carnitine may be connected to its ability to scavenge free radicals.

Characterization of Human Bladder Cell Membrane During Cancer Transformation

Phenomena associated with changes in cell membranes are thought to play an important role in the cancer transformation. We hypothesized that the electrical charge of tumor cells can indirectly represent membrane-based changes that have occurred during cell transformation and may indicate tumor cell status. Here, we describe work showing that phospholipids, proteins content, and electric charge, are all altered in the cell membranes of pT2 stage/grade G3 bladder cancer. Qualitative and quantitative phospholipid composition and the presence of integral membrane proteins were identified using high-performance liquid chromatography. Protein composition was determined using selective hydrolysis of isolated bladder cell membrane proteins and peptide resolution. The surface charge density of human bladder cell membranes was determined using electrophoresis. Our results show that cancer transformation is associated with increased phospholipid levels and a decreased level of integral proteins. Moreover, the process of cancer transformation significantly enhanced changes in the surface charge density of the human bladder cell membrane. In conclusion, this study demonstrates that cell membrane structure and function are modified in bladder cancer cells and that further work in this area is warranted.

Influence of green tea on surface charge density and phospholipids composition of erythrocytes membrane in ethanol intoxicated rats.

Ethanol is oxidized to acetaldehyde and then to acetic acid and these processes are acompanied by free radical generation. This paper reports the effect of green tea on electric charge and phospholipids composition of erythrocytes membrane from rats intoxicated with ethanol. Electrophoresis technique and HPLC have been applied to above-menthioned studies. Ethanol administration caused increase in erythrocyte membrane surface charge density and phospholipid composition. Ingestion of green tea with ethanol partially prevented changes in structure and function of membrane caused by chronic ethanol intoxication.

Changes in Phospholipid Composition Studied by HPLC and Electric Properties of Liver Cell Membrane of Ethanol-Poisoned Rats

ABSTRACT Ethanol introduced into the organism undergoes rapid metabolism to acetaldehyde and then to acetic acid. The process is accompanied by formation of reactive oxygen species (ROS), which damage mainly lipids of membrane cells. The effects of ROS can be neutralized by administering preparations with antioxidant properties. The natural preparations of this kind are teas. This paper reports data on the effect of green and black tea on the surface charge density, content of phospholipids, and level of lipid peroxidation products of liver cell membrane of rats chronically intoxicated with ethanol. Surface charge density of liver cells was measured by the electrophoresis method, whereas qualitative phospholipid composition was determined by the HPLC method. Ethanol administration caused an increase in the amount of all phospholipids, in surface charge density as well as in lipid peroxidation products. Ingestion of green and black tea with ethanol partially prevented these ethanol-induced changes, and the action of green tea was stronger than that of black tea.

Changes in protein composition in erythrocyte membrane of ethanol - poisoned rats after administration of teas.

Selective hydrolysis of the protein to peptides, their resolution by chromatography and determination of the amino-acid sequence in individual peptides is one method applied to studies of their modifications and mutations in pathological conditions. The purpose of this work is the determination of the green and black tea effect on peptides and their amino acid contents in integral erythrocyte membrane proteins in ethanol intoxicated rats. It was shown that ethanol intoxication causes a decrease in peptides and their amino acid contents in comparison with the control group. The ingestion of green (black) tea with ethanol partially prevents these ethanol-induced changes.