ABSTRACT
BACKGROUND: Resistance to apoptosis remains a significant problem in the treatment of prostate cancer. Heat-shock proteins (HSP) have been correlated with tumor progression. The role of HSP in prostate cancer resistance to apoptosis is unknown. METHODS: PC-3 and LNCaP prostate cancer cells were heat-shocked and then treated with or without diethyl-maleate, etoposide, cycloheximide, or 3 Gray irradiation. Percent apoptosis was assessed by propidium iodide DNA incorporation. Protein was also extracted for analysis by SDS-PAGE Western blotting. RESULTS: Western blotting confirmed an increase in HSP 27 and 72. These cells were resistant to both chemical- and radiation-induced apoptosis. Cycloheximide and specific oligonucleotides to HSP 72 blocked the increased expression of HSP 72 and the resistance to apoptosis. Mcl-1, Bcl-2, Bcl-X(L), and glutathione-S-transferase (GST) expression were increased in a time-dependent manner after heat shock. CONCLUSIONS: This study demonstrates that HSP expression, specifically HSP 72, inhibits apoptosis in prostate tumor cell lines, which may be mediated by the production of survival factors.
Subject(s)
Apoptosis/physiology , Heat-Shock Proteins/physiology , Neoplasm Proteins/physiology , Neoplasms, Hormone-Dependent/pathology , Prostatic Neoplasms/pathology , Antineoplastic Agents, Phytogenic/pharmacology , Apoptosis/drug effects , Apoptosis/radiation effects , Blotting, Western , Cycloheximide/pharmacology , Etoposide/pharmacology , Glutathione/biosynthesis , Glutathione Transferase/biosynthesis , HSP27 Heat-Shock Proteins , HSP72 Heat-Shock Proteins , Heat-Shock Proteins/biosynthesis , Humans , Kinetics , Male , Maleates/pharmacology , Molecular Chaperones , Myeloid Cell Leukemia Sequence 1 Protein , Neoplasm Proteins/antagonists & inhibitors , Neoplasm Proteins/biosynthesis , Neoplasms, Hormone-Dependent/metabolism , Nucleic Acid Synthesis Inhibitors/pharmacology , Prostatic Neoplasms/metabolism , Protein Synthesis Inhibitors/pharmacology , Proto-Oncogene Proteins c-bcl-2/biosynthesis , Radiation Tolerance/physiology , Tumor Cells, Cultured , bcl-X ProteinABSTRACT
To better understand the effects of dietary fatty acid manipulations on glomerular function, we compared mesangial incorporation, release, and metabolism of arachidonic (AA), eicosapentaenoic (EPA), and dihomo gamma linolenic (DHG) acids. We found marked differences in mesangial handling of these fatty acids. AA was incorporated into lipids of mesangial cells much more rapidly than EPA or DHG. Ionophore-induced stimulation of fatty acid release from mesangial cells prelabeled with [14C]AA, [14C]EPA, or [14C]DHG caused a release of labeled AA greater than DHG much less than EPA, respectively. Preloading mesangial cells with DHG or EPA for 24 h reduced subsequent basal, ionophore-, and hormone-stimulated prostaglandin E2 (PGE2) synthesis. Finally, unlike AA, neither EPA nor DHG was converted to a significant extent by mesangial cyclooxygenase or lipoxygenase. Thus the mesangial metabolism of DHG and EPA differs both quantitatively and qualitatively from that of AA. Furthermore, EPA and DHG inhibit metabolism of AA at the level of mesangial cyclooxygenase.
Subject(s)
8,11,14-Eicosatrienoic Acid/metabolism , Eicosapentaenoic Acid/metabolism , Fatty Acids, Unsaturated/metabolism , Glomerular Mesangium/metabolism , Animals , Arachidonic Acid , Arachidonic Acids/metabolism , Calcimycin/pharmacology , Cells, Cultured , Chromium Radioisotopes , Dinoprostone/biosynthesis , Fatty Acids/metabolism , Lipoxygenase/metabolism , Male , Prostaglandin-Endoperoxide Synthases/metabolism , Rats , Rats, Inbred StrainsABSTRACT
We studied the effects of fish oil on the progression of renal insufficiency in rats with subtotal nephrectomy. Five weeks after a 1-2/3 nephrectomy, sixteen rats were fed two different diets which differed only in fat composition. Lipid in the control diet was primarily beef tallow; that of the experimental diet, menhaden oil. Fish oil-fed rats had significant increases in plasma creatinines, decreases in urinary PGE2 and accelerated death rates. An additional twelve rats underwent 1-1/3 nephrectomies, and the same dietary manipulations, followed by renal clearance, histologic and biochemical studies after 12 weeks on the diets. Fish oil-fed rats again did worse, with decreased glomerular filtration rates and filtration fractions, more proteinuria and more glomerular sclerosis. Glomeruli and slices of cortex, medulla and papillae from rats fed fish oil produced much less PGE2 and TXB2 than dietary controls. Fish oil-induced suppression of renal PGE2 may be deleterious in this model and may outweigh the beneficial effect derived from TXA2 suppression. In contrast to fish oil's potentially therapeutic role in cardiovascular and immune-mediated renal disease, this diet is detrimental in rat renoprival nephropathy. This illustrates the importance of examining the effects of fatty acid manipulation individually for each disease entity.
