Effect of Polyunsaturated Fatty Acids on Doxorubicin Cytotoxicity in Glioma Cells in vitro*

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1 originl ppers Adv Clin Exp Med 2010, 19, 4, ISSN X Copyright y Wrolw Medil University Alij Zjdel 1, Adm Wilzok 1, Młgorzt Ltoh 2, Zofi Dzierżewiz 1 Effet of Polyunsturted Ftty Aids on Doxoruiin Cytotoxiity in Gliom Cells in vitro* Wpływ wieloniensyonyh kwsów tłuszzowyh n ytotoksyzność doksoruiyny w komórkh glejków in vitro 1 Deprtment of Biophrmy, Medil University of Silesi, Sosnowie, Polnd 2 Deprtment of Cell Biology, Medil University of Silesi, Sosnowie, Polnd Astrt Bkground. In norml nd tumour ells, polyunsturted ftty ids (PUFAs) t s intrellulr seond messengers, whih ply role in signlling, prolifertion nd ell deth. PUFAs hve seletive tumouriidl tion nd my lter sensitivity of tumour ells to rdition nd hemotherpy. Ojetives. Investigtion of the ility of exogenous linolei id (LA, 18:2 n-6), α-linoleni id (ALA, 18:3 n-3), rhidoni id (AA, 20:4 n-6), eiospentenoi id (EPA, 20:5 n-3), nd dooshexenoi id (DHA, 22:6 n-3) to modulte sensitivity of humn gliom ells to doxoruiin. Mteril nd Methods. The influene of PUFAs (0 100 µm) on the viility of humn foreskin firolsts (HFF-1), humn gliolstom (SNB-19), nd humn glioms (8-MG-BA, 42-MG-BA) grown in the sene or presene of doxoruiin ws estimted. Viility of the ells ws mesured fter 72 hours of exposure y the WST-1 tetrzolium slt ssy. Results. DHA (25 µm) stimulted growth of firolsts, while LA (50 nd 100 µm) nd AA (100 µm) redued their growth. Gliom ell growth ws not stimulted y the tested ftty ids. EPA (100 µm) nd DHA (100 µm) inhiited viility of 8-MG-BA nd 42-MG-BA gliom ells. SNB-19 gliolstom ells remined resistnt to PUFAs. PUFAs did not modify growth of the firolsts exposed to doxoruiin. PUFAs (100 µm), in prtiulr DHA, enhned doxoruiin ytotoxiity in ll gliom ell lines used. At lower onentrtions, EPA (25 µm) nd DHA (25 µm) deresed doxoruiin toxiity in SNB-19 ells. Similr effet ws oserved for ALA (25 µm) nd AA (25 µm) in 8-MG-BA ells. Conlusion. To inrese doxoruiin ntitumour tivity in gliom ell lines high onentrtions of PUFAs re required. At low onentrtions of PUFAs this tivity n e diminished. These fts should e tken into onsidertion in therpy for ptients with rin glioms (Adv Clin Exp Med 2010, 19, 4, ). Key words: polyunsturted ftty ids, doxoruiin, gliom ells. Streszzenie Wprowdzenie. Zrówno w komórkh prwidłowyh, jk i nowotworowyh wieloniensyone kwsy tłuszzowe (w.n.k.t.) pełnią funkję wewnątrzkomórkowyh, drugorzędowyh przekźników sygnłu w proesh proliferji orz śmieri komórki. W.n.k.t. wykzują selektywne dziłnie przeiwnowotworowe i mogą wpływć n wrżliwość komórek nowotworowyh n nświetlnie i hemioterpię. Cel pry. Zdnie zdolnośi egzogennyh kwsów tłuszzowyh: linolowego (LA, 18:2 n-6), α-linolenowego (ALA, 18:3 n-3), rhidonowego (AA, 20:4 n-6), eikozpentenowego (EPA, 20:5 n-3) i dokozheksenowego (DHA, 20:6 n-3) do modulowni wrżliwośi ludzkih komórek glejków n doksoruiynę. Mterił i Metody. Do oznzeni wpływu w.n.k.t. (0 100 µm) n przeżywlność ludzkih komórek firolstów npletk (HFF-1), glejk wielopostiowego (SNB-19), ludzkih glejków (8-MG-BA, 42-MG-BA) hodownyh w nieoenośi i oenośi doksoruiyny zstosowno test WST-1. Przeżywlność komórek ył mierzon po 72 godzinh ekspozyji. Wyniki. DHA (25 µm) stymulowł wzrost firolstów w przeiwieństwie do LA (50 i 100 µm) orz AA (100 µm), które hmowły ih wzrost. Bdne kwsy tłuszzowe nie stymulowły wzrostu komórek glejków. EPA (100 µm) * This work ws supported y SUM grnt KNW-2-005/10.

2 482 A. Zjdel et l. orz DHA (100 µm) zmniejszły przeżywlność komórek glejków linii 8-MG-BA i 42-MG-BA. Komórki glejk wielopostiowego SNB-19 nie wykzły wrżliwośi n w.n.k.t. W.n.k.t. nie modyfikowły wzrostu firolstów eksponownyh n doksoruiynę. W.n.k.t. (100 µm), w szzególnośi DHA, zwiększły ytotoksyzność doksoruiyny woe wszystkih testownyh linii glejków. W mniejszyh stężenih EPA (25 µm) orz DHA (25 µm) zmniejszły ytotoksyzność doksoruiyny w linii komórek SNB-19. Podone dziłnie zoserwowno w przypdku ALA (25 µm) i AA (25 µm) w komórkh 8-MG-BA. Wnioski. Zwiększenie ktywnośi przeiwnowotworowej doksoruiyny woe komórek linii glejków wymg zstosowni w.n.k.t. w dużyh stężenih. W młyh stężenih kwsy te mogą spowodowć zmniejszenie przeiwnowotworowej ktywnośi doksoruiyny. Fkty te powinny yć rne pod uwgę w lezeniu pjentów z glejkmi mózgu (Adv Clin Exp Med 2010, 19, 4, ). Słow kluzowe: wieloniensyone kwsy tłuszzowe, doksoruiyn, komórki glejków. Essentil ftty ids, suh s linolei id (LA, 18:2 n-6) nd α-linoleni id (ALA, 18:3 n-3), re widely distriuted in humn food ut nnot e synthesized y mmmlin ells. Both LA nd ALA re preursors for the synthesis of longer hined polyunsturted ftty ids (PUFAs), ruil for norml ellulr funtion. Thus, γ-linoleni id (GLA, 18:3 n-6), dihomo-gla (DGLA, 20:3 n-6) nd rhidoni id (AA, 20:4 n-6) re formed from LA, wheres eiospentenoi id (EPA, 20:5 n-3) nd dooshexenoi id (DHA, 22:6 n-3) from ALA. PUFAs hve een shown to prtiipte in numerous ellulr funtions ffeting memrne fluidity, memrne enzyme tivities nd eiosnoid synthesis. Either in norml or trnsformed ells, PUFAs t s intrellulr seond messengers, whih prtiipte in signlling, prolifertion nd ell deth [1, 2]. During the therpy of ner it is desired tht gents preferentilly kill tumour ells without exerting dverse effets on norml ells. In this ontext, it is interesting to note tht PUFAs hve seletive tumouriidl tion in vitro nd in vivo [3], show ntingiogeni tion [4, 5] nd my inrese sensitivity of tumour ells to rdition nd hemotherpy [6, 7]. In ddition, PUFAs were reported to reverse tumour ell drug resistne [8], mjor prolem in onology prtie. There is n inverse reltionship etween onentrtions of lipid peroxides nd the rte of ell prolifertion. Tumour ells hve low onentrtions of lipid peroxides nd re resistnt to lipid peroxidtion ompred to norml ells [9]. The low rte of lipid peroxidtion nd levels of lipid peroxides in the tumour ells ould e ttriuted to their low ontent of PUFAs. The low ontent of PUFAs in the tumour ells is due to the loss or deresed tivity of Δ6 nd Δ5 desturses [10], enzymes tht re essentil for the formtion of more highly unsturted, long-hin ftty ids. It ws shown tht lol PUFAs defiienies in tumour ells my e retified y the supplementtion with exogenous PUFAs [11]. The deline in struturl nd funtionl integrity of rin tissue, whih is prtiulrly rih in PUFAs (minly DHA), ppers to orrelte with loss in memrne DHA onentrtions. AA, lso predominnt in rin tissue, is mjor preursor for the synthesis of eiosnoids, intrellulr or extrellulr signlling moleules [12]. PUFAs hve een reported to stimulte tumour regression in humn gliom nd poptosis in gliom ells in vitro nd in vivo [3, 5, 13 15]. In the present study we investigted the ility of exogenous LA, ALA, AA, EPA, nd DHA to modulte sensitivity of ultured humn gliom ells to doxoruiin, n ntiner drug ommonly pplied in the tretment of mlignnt glioms. Mteril nd Methods Cell Culture SNB-19 humn gliolstom ell line, 8-MG- BA, nd 42-MG-BA humn gliom ell lines were otined from the Germn Colletion of Miroorgnisms nd Cell Cultures (DSMZ). HFF-1 foreskin firolsts were purhsed from the Amerin Type Culture Colletion (ATCC). SNB-19 nd HFF-1 ell lines were ultured in Duleo s Modified Egle s Medium (DMEM) ontining 10% het intivted fetl ovine serum (FBS; PAA The Cell Culture Compny), 100 U/ml peniillin, nd 100 µg/ml streptomyin (Sigm). 8-MG-BA nd 42-MG-BA ells were grown routinely in Modified Egle s Medium (MEM) supplemented with 10% het intivted fetl ovine serum (FBS; PAA The Cell Culture Compny), 100 U/ml peniillin nd 100 µg/ml streptomyin (Sigm). Cells were mintined t 37 o C in humidified tmosphere of 95% ir nd 5% CO 2. Cell Exposure to Doxoruiin nd PUFAs Doxoruiin, linolei id (LA, 18:2 n-6), α-linoleni id (ALA, 18:3 n-3), rhidoni id (AA, 20:4 n-6), eiospentenoi id (EPA, 20: 5 n-3), nd dooshexenoi id (DHA, 22:6 n-3)

3 Cytotoxiity of PUFAs nd Doxoruiin in Gliom Cells 483 were purhsed from Sigm. Stok solutions of doxoruiin were prepred in physiologil sline solution (NCl 0.9%). The ftty ids were dissolved in 99% ethnol nd stored s stok solutions (100 mm) under nitrogen t 20 C. To hieve the required onentrtions ftty ids nd doxoruiin were prepred from stok solutions nd diluted with the pproprite growth medium freshly efore eh experiment. Cells were seeded in stndrd 96-well pltes ( ells/well in 100 µl). One dy fter seeding, the ulture medium ws removed nd repled y the sme medium ontining 0.1% ethnol (ontrol), PUFAs (25 µm, 50 µm, 100 µm) or PUFAs nd doxoruiin t IC50 (0.12 µm for HFF-1 ells nd 0.38 µm for gliom ells). Control ells were ultured in the medium ontining the sme onentrtion of ethnol (v/v; 0.1%) s the experimentl ultures. The ethnol solution in suh onentrtion hd no notiele influene on the prolifertion of the experimentl ultures. Cytotoxiity Assy Viility of ells ws mesured fter 72 hours y the tetrzolium slt ssy. WST-1 regent (10 µl, Rohe Dignostis GmH) ws dded to eh well. The pltes were gently gitted for 1 min, nd the ells were inuted with the WST-1 regent for 1 hour in 5% CO 2 t 37 o C. Metolilly tive ells redued the dye to purple formzn. Following inution, the sorne t 440 nm ws determined using miroplte reder (UVM340, Biogenet). Cell viility ws expressed s perentge of sorne mesured in the treted wells reltive to tht in the untreted ontrol wells. Sttistil Anlysis The dt otined from 3 independent series of experiments were expressed s men vlues ± stndrd devitions. Sttistil signifine nlysis sed on nlysis of vrine (ANOVA) followed y Tukey s HSD test. The P-vlue of less thn 0.03 ws onsidered signifint. Sttistil nlysis ws performed using Sttisti 8 PL softwre for Windows (SttSoft, Polnd). Results Effet of PUFAs on Cell Viility Tle 1 shows results of viility tests performed fter 72 hours of exposure of humn foreskin firolsts, whih were used for omprison with tumour ells, nd three gliom ell lines to linolei, α-linoleni, rhidoni, eiospentenoi, nd dooshexenoi id. Results were expressed s perentge of viility of PUFA-treted ells vs. ontrol ells. Ftty ids dded to the ultures in the onentrtion rnge µm generted diverse effet in the tested ells. Among the ftty ids used, only DHA (25 µm) stimulted growth of firolsts (110.7% of ontrol, P = ), while LA (50 nd 100 µm) nd AA (100 µm) redued their growth y out 10%. In no se gliom ell growth ws stimulted y the ftty ids. EPA (100 µm) nd DHA (100 µm) inhiited viility of 8-MG-BA nd 42-MG-BA gliom ells. The effet of DHA ws more pronouned. SNB-19 gliolstom ells remined resistnt to PUFAs. Effet of PUFAs on Doxoruiin Cytotoxiity The results of mixed tretment of firolsts nd gliom ells with PUFAs in vrious onentrtions nd doxoruiin (IC50) dded to the ultures simultneously, re summrised in Tle 2. To llow omprison with the effets of PUFAs (Tle 1), the ell viility of PUFA+ DX-treted ells ws lso lulted s perentge of ontrol. PUFAs did not modify growth of firolsts exposed to doxoruiin. But when LA (100 µm), ALA (100 µm), AA (100 µm) or DHA (100 µm) were dded to 8-MG BA nd 42-MG-BA ultures, sttistilly signifint inrese of doxoruiin effet ws oserved. At lower onentrtions of these ids (50 µm) this effet ws not oserved nd, in the lowest onentrtion, ALA (25 µm) nd AA (25 µm) redued ytostti tivity of doxoruiin in 8-MG- BA ells. In gliolstom SNB-19, the ddition of ALA, EPA or DHA (100 µm) enhned doxoruiin ytotoxiity ut EPA (25 µm) nd DHA (25 µm) diminished this effet. Among the ll ftty ids tested DHA (100 µm) inresed ntitumor tivity of doxoruiin in the highest extent. Disussion PUFAs re importnt omponents of memrne phospholipids. Chnges in PUFAs hve een shown to modulte memrne struture, fluidity, nd funtion. Ftty ids indue modifitions in the ell memrne struture nd ffet vrious ellulr proesses. Severl reports showed n inrese of the PUFAs ontent of tumour ells y ltering the ftty id omposition of the growth medium in vitro [6, 14, 16] or y feeding PUFAs to lortory nimls implnted with tumours [17]. It ws proved tht it might e possile to influene the lipid omposition of ells y ontrolling the type

4 484 A. Zjdel et l. Tle 1. Cytotoxiity of linolei id (LA), α-linoleni id (ALA), rhidoni id (AA), eiospentenoi id (EPA), nd dooshexenoi id (DHA) in humn foreskin firolsts (HFF-1), humn gliolstom (SNB-19) nd humn glioms (8-MG-BA, 42-MG-BA) expressed s perentge of viility of PUFA-treted ells vs. non-treted ells Tel 1. Cytotoksyzność kwsu linolowego (LA), α-linolenowego (ALA), rhidonowego (AA), eikozpentenowego (EPA) i dokozheksenowego (DHA) w komórkh firolstów npletk ludzkiego (HFF-1), glejk wielopostiowego (SNB-19), ludzkih glejków (8-MG-BA, 42-MG-BA) wyrżon jko proent przeżywlnośi komórek eksponownyh n w.n.k.t. względem komórek nieeksponownyh PUFA (W.n.k.t.) PUFA onentrtion (Stężenie w.n.k.t.) µm Cell viility (Przeżywlność komórek) % HFF-1 SNB-19 8-MG-BA 42-MG-BA LA ± ± ± ± ± ± ± ± ± ± ± ± 1.65 ALA ± ± ± ± ± ± ± ± ± ± ± ± 2.94 AA ± ± ± ± ± ± ± ± ± ± ± ± 2.02 EPA ± ± ± ± ± ± ± ± ± ± ± 4.66, ± 4.42, DHA ± ± ± ± ± ± ± ± ± ± ± 1.40, ± 2.88, sttistilly signifint differene in omprison with ontrol; P < sttistilly signifint differene in omprison with ontrol; P < sttistilly signifint differene in omprison with oth EPA treted ells nd DHA treted ells; P < istotn sttystyznie różni w porównniu z grupą kontrolną; P < 0,03. istotn sttystyznie różni w porównniu z grupą kontrolną; P < 0,0003. istotn sttystyznie różni w porównniu zrówno do komórek trktownyh EPA, jk i trktownyh DHA; P < 0,0003. of lipids dded to the ulture medium. Numerous studies tht hve een onduted on vrious ner ells hve ttempted to determine the ntitumourl effets of n-3 nd n-6 series ftty ids [11, 18]. Only few of these studies hve een onduted on humn gliom ell lines [6, 14, 15]. PUFAs re ple of stimulting poptosis of humn gliom ells [14, 19, 20]. However, mrked differenes in the effetive doses of PUFAs in vrious gliom models hve een reported. Moreover, low onentrtions of PUFAs nd their metolites my stimulte tumour prolifertion [14, 21]. In this study the omprison of the effets of LA, ALA, AA, EPA, nd DHA on the viility of firolst HFF-1 nd gliom SNB-19, 8-MG-BA, nd 42-MG-BA ell lines ws mde. LA (50 µm, 100 µm) nd AA (100 µm) deresed viility of the firolsts, DHA (25 µm) stimulted their growth nd the other ftty ids tested did not show signifint effet within the onentrtion rnge pplied. When the PUFAs were dded to the gliom ell ultures, only EPA (100 µm) nd DHA (100 µm) deresed the growth of 8 MG BA nd 42-MG-BA ells, showing seletive tumouriidl tion. The oserved effet of DHA ws more severe thn tht of EPA. These results re similr to those reported for C6 gliom ells, tht GLA, AA, EPA nd DHA, seletively kill tumour ells with little or no effet on the survivl of norml ells [14, 19, 22]. In own study, none of the tested PUFAs modified viility of SNB-19 gliolstom ells.

5 Cytotoxiity of PUFAs nd Doxoruiin in Gliom Cells 485 Tle 2. Effet of linolei id (LA), α-linoleni id (ALA), rhidoni id (AA), eiospentenoi id (EPA), nd dooshexenoi id (DHA) on the viility of firolsts (HFF-1), humn gliolstom (SNB-19) nd humn glioms (8-MG-BA, 42-MG-BA) grown in the presene of doxoruiin (DX). Cell viility hnges were expressed s perentge of viility of DX treted ells nd PUFA + DX treted ells vs. non-treted ells Tel 2. Wpływ kwsu linolowego (LA), α-linolenowego (ALA), rhidonowego (AA), eikozpentenowego (EPA) i dokozheksenowego (DHA) n przeżywlność komórek firolstów npletk ludzkiego (HFF-1), glejk wielopostiowego (SNB-19) i ludzkih glejków (8-MG-BA, 42-MG-BA) hodownyh w oenośi doksoruiyny (DX). Zminy w przeżywlnośi komórek trktownyh DX orz w.n.k.t. i DX wyrżono w proenth względem komórek nieeksponownyh n te związki PUFA (W.n.k.t.) PUFA Conentrtion (Stężenie w.n.k.t.) µm Cell viility (Przeżywlność komórek) % HFF-1 SNB-19 8-MG-BA 42-MG-BA DX* ± ± ± ± 5.56 LA + DX ± ± ± ± ± ± ± ± ± ± ± ± 0.57 ALA+ DX ± ± ± ± ± ± ± ± ± ± ± ± 1.35 AA+ DX ± ± ± ± ± ± ± ± ± ± ± ± 0.65 EPA+ DX ± ± ± ± ± ± ± ± ± ± 3.33, ± ± 1.15 DHA+ DX ± ± ± ± ± ± ± ± ± ± 0.17, ± 0.79, ± 1.07, DX* onentrtions were equl to IC50 for eh ell line respetively (see Mteril nd Methods). sttistilly signifint differene in omprison with ells treted with DX; P < sttistilly signifint differene in omprison with ells treted with DX; P < sttistilly signifint differene in omprison with oth EPA + DX treted ells nd DHA + DX treted ells; P < DX* stężeni yły równe wrtośiom IC50 dl kżdej linii komórek (zo. Mterił i metody). istotn sttystyznie różni w porównniu z komórkmi eksponownymi n DX; P < 0,03. istotn sttystyznie różni w porównniu z komórkmi eksponownymi n DX; P < 0,0003 istotn sttystyznie różni w porównniu zrówno do komórek trktownyh EPA + DX, jk i DHA + DX; P < 0,0003. The effets of dietry PUFAs on the prevention nd therpy of ner re still fr from ler. PUFAs re known to indue retive oxygen speies genertion nd use lipid peroxidtion in tumour ells nd led to ltered mitohondril metolism, ytohrome relese, spse tivtion, nd poptosis [22]. Both PUFAs nd their metoli produts n lter the expression of severl proteins. PUFAs suppress the expression of onogene rs, inhiit tht of Bl-2 nd enhne the tivity of p53 [23, 24]. In ddition, PUFAs oost the formtion of lipid peroxides due to ugmented free rdil genertion in tumour ells [16, 19, 25]. One of the mjor prolems of gliom progression in vivo is intense ngiogenesis, whih hs een relted not only to tumour nutrition ut lso to tumour ell migrtion long the sement memrne of the growing lood vessels [26]. In glioms, the est hrterized prongiogeni ftor is vsulr endothelil growth ftor (VEGF), whose overexpression is orrelted with inresingly mlignnt phenotypes [4]. GLA, AA, EPA, nd DHA my

6 486 A. Zjdel et l. hve ntingiogeni tion [4, 22]. It ws lso demonstrted tht inhiitors of AA metolism hve suppressive tion on ngiogenesis in vivo [27]. PUFAs my intert with ntiner gents during hemotherpy. Exogenous PUFAs re redily inorported into ner ell memrnes. Biohemil modifitions of memrne ftty ids my led to ltertion in drug trnsport nd, hene, my modulte ell sensitivity to ntiner drugs. PUFAs inorported to the tumour ells my lso serve s sustrtes in retions, whih generte high mounts of free rdils during ntiner progression nd therpy [9, 18, 25]. The uthors exmined the influene of vrious PUFAs on doxoruiin indued ell toxiity. Among the methods ville to ssess ntiner drug tivity, they hose to mesure ell mitohondril tivity rther thn ell prolifertion. The uthors found tht in 8-MG-BA ells low onentrtion of ALA redued, while high onentrtion inresed ntiner tivity of doxoruiin. Similr effet ws oserved for EPA nd DHA in SNB-19 ell line. DHA (100 µm) ws the most effetive nd sensitised ll the gliom ell lines tested to doxoruiin nd did not ffet firolsts. Own findings gree with the reports tht inution of humn gliolstom ells A-172 nd U-87MG with non-toxi doses of DHA enhned ytotoxiity of doxoruiin. DHA enhned sensitivity to doxoruiin in the gliolstom ells ws more pronouned in ells resistnt to DHA [7]. In the present study the uthors showed tht the effets of PUFAs on the firolsts nd glioms n e highly diverse. Generlly, PUFAs did not influene or slightly inhiited growth of firolsts. In the tumour ells treted with doxoruiin PUFAs, mostly DHA, enhned ytotoxiity of this ntiner drug. Very high onentrtions of PUFAs re required to inrese doxoruiin ntitumour tivity in gliom ells. At low onentrtions of PUFAs this tivity n e notiely deresed. The ltertions of doxoruiin ytotoxiity indued y PUFAs t onentrtions, whih n result from the dietry intke or supplementtion, should e tken into onsidertion in therpy of tumour ptients. Referenes [1] Eynrd AR: Potentil of essentil ftty ids s nturl therpeuti produts for humn tumors. Nutrition 2003, 19, [2] Bentti P, Peluso G, Nioli R, Clvni M: Polyunsturted ftty ids: iohemil, nutritionl nd epigeneti properties. J Am Coll Nutr 2004, 23, [3] Ds UN: Gmm-linoleni id therpy of humn gliom review of in vitro, in vivo, nd linil studies. Med Si Monit 2007, 13, [4] Miyke JA, Bendi M, Colquhoun A: Gmm-linoleni id inhiits oth tumour ell yle progression nd ngiogenesis in the orthotopi C6 gliom model through hnges in VEGF, Flt1, ERK1/2, MMP2, ylin D1, pr, p53 nd p27 protein expression. Lipids Helth Dis 2009, 8, 8. [5] Ds UN: Tumoriidl nd nti-ngiogeni tions of gmm-linoleni id nd its derivtives. Curr Phrm Biotehnol 2006, 7, [6] Vrtk S, Roins ME, Spetor AA: Polyunsturted ftty ids inrese the sensitivity of 36B10 rt stroytom ells to rdition-indued ell kill. Lipids 1997, 32, [7] Rudr PK, Krokn HE: Cell speifi enhnement of doxoruiin toxiity in humn tumor ells y dooshexenoi id. Antiner Res 2001, 21, [8] Ds UN, Mdhvi N, Srvn Kumr G, Pdm M, Sngeeth P: Cn tumor ell drug resistne e reversed y essentil ftty ids nd their metolites? Prostglndins Leukot Essent Ftty Aids 1998, 58, [9] Mhéo K, Viet S, Steghens JP, Drtiges C, Lehmn M, Bougnoux P, Goré J: Differentil sensitiztion of ner ells to doxoruiin y DHA: A role for lipoperoxidtion. Free Rdi Biol Med 2005, 39, [10] Hnsen-Petrik MB, MEntee MF, Johnson BT, Oukowiz G, Msferrer J, Zweifel B, Chiu CH, Wheln J: Seletive inhiition of Δ-6 desturse impedes intestinl tumorigenesis. Cner Lett 2002, 175, [11] Berquin IM, Edwrds IJ, Chen YQ: Multi-trgeted therpy of ner y omeg-3 ftty ids. Cner Lett 2008, 269, [12] Youdim KA, Mrtin A, Joseph JA: Essentil ftty ids nd the rin: possile helth implitions. Int J Dev Neurosi 2000, 18, [13] Lever HA, Whrton SB, Bell HS, Lever-Yp IM, Whittle IR: Highly unsturted ftty id indued tumour regression in gliom phrmodynmis nd iovilility of gmm linoleni id in n implnttion gliom model: effets on tumour iomss, poptosis nd neuronl tissue histology. Prostglndins Leukot Essent Ftty Aids 2002, 67, [14] Lever HA, Bell HS, Rizzo MT, Ironside JW, Gregor A, Whrton SB, Whittle IR: Antitumour nd pro-poptoti tions of highly unsturted ftty ids in gliom. Prostglndins Leukot Essent Ftty Aids 2002, 66, [15] Lever HA, Willims JR, Smith C, Whittle IR: Intrellulr oxidtion y humn gliom ell popultions: effet of rhidoni id. Prostglndins Leukot Essent Ftty Aids 2004, 70,

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