Document N2m66bb96wYn4znneE0EBRwe8

//,.( * / v ' % omparative Mammalian Metabolism Chloride in Relation to Oncogenic Potential by David E. Hathway - Klucidution of ;hr roll- of vinvl chloride metabolites in the various reaction sequences which comprise the metabolic pathway, including the interaction of reactive metabolites with some purine and pvrimidine residues of target-organ UNA, provides some explanation for the (oncogenic i properties associated with the original substance. Comparative investigation of the biological fate of vinvlidene chloride reveals an agent of low oncogenic potential which is likely to he damaging only under special circumstances, and s|>ecies differences which suggest that the mouse is more susceptible than the rat towards vinvlidene chloride oncogenicity. I ho research work with which this communica tion is concerned is bused on tbe idea that know ledge ^'the hiologv of the reactive metabolites of chemical Brcinogcns in the mamma!, including the precise nature of the chemical changes to the I)NA of the nucleus, ought to give an insight into the (oncogenic) properties of the parent compounds. In tracer studies. A'-nceiyl-.V-(2-hydroxymethyl)eysteine was shown to be a major vinyl chloride metabolite in rats, but according to the method of protective esterification that was used so a derivative either of .Y-acety!-.V-(2-ch!oroethyl)cysteine or of Y-acet>l-.V-(2-h>dro.\yethyl)cysteine was isolated from body fluids (/. 2), Thus, by b'iseher-Speier methylation..Y-aceiyl-.S-(2-chloroeth\l)cysteinc was obtained, and with dia/omethane. .Y-acetyl,S-(2-hvdroxyethylicysteine. It might be stilted in passing that throughout the investigations de scribed. mass spectrometry,. involving electron im pact (HI) and chemical iom/aiion sources and multiple-ion detection and all combinations ot these facilities, was used extensive!) hoth for product identification and analysis and lor the purposes ot detection. I reatmem of the (7-methyl ester of .V-;iceiyl-.V-(2-hydro\>etfH licvsteine (a) with the methanol-NCI reagent gave a mixture of ,Y-acetyl-.V-(2-chloroeth> l)c\steinc (hi. and S(2-chloroethyl)e> steine. and conversely, the (Mnclhvl ester of Y-acetyl-.S-(2-chioroethy!)cysteine (b) was hydroly/ed rapidly by water to that of A'-acetyl-.S-(2-hvdro.\yethyl)cy.steine (a) (2). Hence, the reversible reaction processes connecting the two substances would seem to be modulated through the intermediacy of episulfonium ion (e> and formation of this ion would in fact be rate-limiting in respect of the hydrolysis of (a > OH H l M OH 'T-C --- H'"l 'H -OH SR (b! Ci H. -C` X< S r" r ' SN C11, *lmpciul Chemical Industries Limited, Cemtal lowcalogv t.aKuauirv. Aldcrlev Park. < heshire Shi II) J`!J, Lnglatid December 1977 B8 to cn oo oo CO ' r l *#A, R&S 025884 A -acetv I-A -s'.ethv I w su-m \ 'iv Iconhlhs ^l,ick ot ()!i 0:1 th'j I'm-P;:;n i`!i Oil Id 'V ^^POCtcd u> g'.\C :d .! !,.l. A- acetv i-.S v m\lev sk'iHc ill) ` - 'Vied f'ivri! t lie ut ine s'? \ i!' \ ,, :, i u ^ - -t ! t ni ;i t ^ uheneves d:a/omci!>.uie esk-:1! e.: protect A-eontamtng ;:is Uim'bm- i-s iiscU to Surprisinglv , Y-.iccty i-.S -i 2-hyd; o\v c: h> I >cy - steine (J-methy 1 esies was methylated uirh neu tral methanol, and the (J-methyi esteis o! Y-acetyi- A'~(2-meiho.\y [1 *(' Jethy 1 icy steine plus Y-acetvI- A-| "Cjvinyf e\-acme degrade to give the volatile f1 *C ]i>-(2-metho\y ethy I> (piop-i sir 2-envil sulfide. Although the mechanism ot formation was not inves tigated, we Jolt that acetaldehyde, a known dissocia- tion prodiiet of .S-\iny Icy steine-denv ed .V-vinyl- eysteine*.V*v.\ide H* > might undergo concerted con densation with A'-aoety kV-(2-mciho\yelhy I ley steine leading to elimination of thermodynamically stable glvoxylate. [There s an analogs tor such a concerted condensation reaction in the v-o* k of Dahrit/ and V irtanen t-k m the tear-pioduuns: voltitile compo nents of the onion,! 1 he halt-nmstard ,S -containing metabolites of vinyl chloride did not behave as mutagens m the Ames test C i. 1 hiodiglyootlic acid is another majot v inv! chloride j^krbolite if). order to determine whetner vinyl chloride yielded chloroethylene oxide in vivo, the biogenesis of several vinyl chloride metabolites and related compounds were investigated in iats (2). Y- (2-Hvdroxyethylieysteine gave (> 5rr of the authentic thiodiglycollic aeiu. and this result was seen to be highly significant, because id the instability (e. supra) of the starting material unde; exceedingly mild conditions of leactiou ! 1 v Met.iN.tie pathway concerned [i-'q. M); appear' '<> include endgroup oxidation th. amino-a-. id ''.u' .amiaaiiori (lb, and oxidative deeaibovy iation tad tin. I'esults of the animal feedi1:; cvpct'n'cuis suggest that chloroacetaldehyUi: igi chinipucciiv acid iht, and A-(2-carboxymethyltcystewe ii' mam; lie on a com mon pathway contacting vinvi chloride (e) with thiodiglycollic acid (jr iowevet, oiiiei evidence im plies that chloroacetic ucd (hi lines not belong to this metabolic pathway ie-ji. i hits, (Kls even been detected in the bodv fiuids of tun of our vinvi Lh; V F. * d, 0.,`s - C". C L-CS* - vCH,cts^ ill *r',r. >*'. f r' Mi. J f d t *,( r **r ^ v *j, r;V: cmc i1 MH'Ae -! ` 0" Cm' -0M rn,, p-S'-ii 1 "'Lh. CC-*;'cVfYV t*Ss S'CM-CC^H^ Ip chloride-treated animals, hither there is a high rate of turn-over or this compound is not a major vinyl chloride metabolite. 1 he latter possibility seems more likely, since relatively laige amounts are pi\`duced in vjnylidcne chloride metabolism, and in those animals, thiodiglycollic acid accounts for an even greater proportion of tin' dose than m parallel experiments with vinyl chloride. A feasible metabolic pathway for thiodiglycollic acid from chloroacetic acid and involving cysteine desulfhydrase is unacceptable. I:\periments with unlabeled vinyl chloride in rats in which the cysteine-cystine pools had been labeled adequately with **C gave f'Vjthiodiglyeollie acid, showing that a part of the ('-skeleton must b:' derived in fact from cysteine. In rats treated w ith ehloroacetaldelmie. the presence of thiodiglycollic acid and A'-acetyl-.V-<2-hydroxycthyltcysteine. but not of chloroacetic acid, among the Urinary metabolites was established by mass fragiiientometry. Thus, it is probable that h; \n-> chloroethylene 5r> Environmental Health Perspectives R&S 025885 avide il ' u.in la >1 sh >1 Utcd ^pl >' f l:ou; \ s t ^ ? ..f;U'`'dc U ami 'Mt't t:' ' kdchvdc it:, rheiv a tmt: ^vtdvme i7 !<>\ Hi "v my ! chiv'i idc cpovidation >. . >* } he- .apposition a H -"x '.At'' !h.;- i. '1 ' ' > ' 1 ' ! ''I xt!. X a,. C I l - \ t . ' A 111 i * \ \ X" ` * , ' A '* ' * V ' '- .lid ihiodiclvHi A ,U:d - ,i . .;>>,! S 1' ui'i'iA} mcibv b . v stcme bus !vi-n iiicatilied bv bagmeniomeua .ewimes' the imholv'ic pt.>t!i. *n! .t't hepatic tA'u: piepatvd bom wn-.! chloride- beatcd animals Snu'c vhlorouxci.ddehv dc -mil chioroothy lone inaii.- arc mutagenic m the Ames te-i <//'/.') anJ in l Irniese hnmsiei V"9 cells </J j, they may he lelevunt to vinyl chloride carcinogenic); > Respective formation v'l vie-aw nbobu- atK'sy limida/o -1 2. J - i; puri ne at vV- i>- 2' - Jen \ y nboluranosy l-2-o\o-2..'-dihy droimidu/u-l 1,2-c|py - rimidme bom dooxy adenosine o: dcoxy cytidinc by i eviction with chlot oacetaldehyde (15) or chloro- ethylene oxide was readily confirmed. Recognition ot the nucleoside units of DNA that were modified by icaci ion u till active \ iny I chloride metabolites in wiu pun-ides opportunity, lot the construction from appn'p' tate animal data of the corresponding doseresponse. time-response relationships. in eompa: so;i with the ones fur tumor incidence.'occurrencc in those animals. The presence of these two im- la/.onucleoside derivatives has now been estabshevl hv mass fragmentometry (16) in the eri/ymic 1 ,/ I ; s.l .. _ :!'\i i -'V :S'.- I: l. .: f 1 f C I ! *'! - * > I ,i,!.m I.,, t re-.1 1 r: -iiimH-. [)S. X ..n.- TI >. ,,. a..!''V' -H-O ' - .- ! \ mv` ?:!*: nit* Hx:!i r o.>-:>- 1 .i!(i>iJ '/(-nC ril'nrta- t-'v ... ; : i.a, ..'si-f t . 2-e Nv i iimdint- Mv't tvusi -.i'll-1 /M> (!c"M rit'.i!n;.iTi<''vlmlid.i/*i- H! i fi'in in-- >: Wi'r'- u.ir.-! i hydrolysate of modified ial-liver DNA. prepaired from rats, which had been exposed chronically to vinyl chloride (250 ppm ;,t their drinking water) for 1 year (Hu. 1). A smaller proportion of t he 9/d-n-2 `-deox y rihufurtino'.v limiviazo- [2.!-ijpurine. than would have been expected to have been tornivd. was I'omui both in tH animal experiments with vinvl ehloitde and in model teac- tions between chloioacetnkiehvde and calf thymus DNA I his obseivation is consistent with some degree of DNA vlepmillation brought moiit bv the reaction of vinvl chloride, and in our model experiments, we have found evidence lor the pres ence of the detached purine, vi/.. imida/o-|2.! *i; pminc Hence, the alkylation tint? produces miida/O'dciivative formation (with DNA) labih/c*- the N,,-purine gJ-glv voside linkage, which leads to ilepurination. I he gap so produced might then be filled by various bases, iexulting in "mispairing" during DNA replication. 1 hese results are very im portant. because in general, there is excellent auucment hetween the severe damaging effect of depurination to DNA and mutagenicity (I7-11)). Thus, in retrospect, one-would, suspect vinyl lloride of being mutagenic/carcinogenic. On the other hand, vinylidene chloride (k) metabolism in rats gave ihiodiglycollic acid (rl and an A -aeetyl-.V-cysteinv l-acet> I derivative (p) as major urinary metabolites, phis substantial amounts of ehloroaceti-c a;id di. dithioglyeollie acid <U and thioglyeollie acivi is) (2ft). It is probable that chloroaeelic acid d). which is a vinylidene chloride metabolite /n-r ,\c. hes on a major metabolic path way for vtnvlidenc vhlomle. since it afforvls several mel-tb'dae' m eummo!-; wii'u vinylidene chloride (2d). Iheic is a siiouu supposition that detoxification of chloroaeelic aea* di is effected through a gluta thione o-acyl iianslerase-eatalv/ed reaction pro ves1. mid ensuing degiadative sequence for the re sulting ir.eihylgiaiathione in), and that this represents the principal metabolic pathway for chloroaeetic acivi and a majoi one for vinylidene chloride. TbiodiglyvoU'c acid is the ultimate detox ification proviuei, .-tivl previous work (2) established the hiotransforr: 'ion of .V-(2-carboxymethyl) cys teine tg) intv) Ih.u substance. A feasible metabolic 'pathway to 'hiodiglycollic acid from ebloroacetic acid and involving cysteine desulfhydrase i> unac ceptable. In experiments (rats) with unlabeled vinylidene chloride, in which the cysteine-cystine pools had been lahejed with l4C, labeled thiodigly- eollic acid resulted, and a part of the O-skeleton of December 1977 . ; -- 57 - that subst.uu v iiiim he ili iiu J it; bn', fiom c> stcme ** i.'Ui I oi m.Uiou >! nmoem ot ''`l jthiodi gbcollic acid I! rand i! v t * ^ v ot tile Intel mediate |: *( jtlnodieh colhe .u ui <" is ie>.one liable w ith the action ot Michachs's Ci > unspec tftc /Fthiouase. winch uaiilu b sc ,i sni.iii pjopoition of the ptepon dciuting '( 'thiodieb ..oIIk av id. MiMoaii", kollv v!.`\!h*i\ 'is i.'.'i n! oik1 mokvtt !.ii piopostton t'i the :( hfnedigbcoliic acid nielaboiiie troin ! ( ! !.!-dichlot octln lene 01 il' H ;Vh!oi oncetic acid gave oik* <.-<.}!m\alcni ot 't ).kV>. and this cadence is consistent with the t raiisfoi mat ton ol` vun lidene chloude into cldoioacetic noii! In a mechanism involving migra tion of oik* ('1 atom amt the loss of the other one CO, Hence, the metahoiic pathway which was tent' lively pioposed lot ihe biotr.mslbrm.it am of vinylidene chloiidc into thiodigb collie acid does in tact operate in iats It is equivocal whether the very small amounts of C t and urea are pi odneed by the action of epoxide hydrniase on I, I-dichlot oetln lene o\ide or by a inmoi i'\tdali\e pathv.a\ foi chloroaeelie acid Iheie is a strong supposition that the \ -acetyl-V-eysteiny lacely I derivative (pi. w hich is a metabolite ot vinylidene chloride, but not of cldoioacctic acid. ma> be burned in fact from I. I-dichloioethylene oxide through the agenev ol glutathione ,S-epo\ide transferase to al'lotd k S-glutathione ace! y I cldoi isle (ml and its subsequent w icactions tA'i. | his supposition is important, since the reactivity display ed by i. I-dichloroethy lene oxide appears to he relevant to the possiblepnleraction of react iv e v iny lidene chloride metabolites w ith mouse kidney I)N A 11 ig. 2b which is a prerequisite of tumoi initiation i_'dq Such inieniciioit would be analogous to that s't vinyl chloiidc with lat-lo-ei I )N \ in \ ii o. w his h forms imida/o deriv ativ _s w ith some nucleoside residues i/P). Further work is in pi ogress to investigate this hypothesis. Comparative studies i.Vi pi oxide clues ol dilfeicnees between iats ;uul mice in the piocessing of \ my lidene chloiidc t fable lb Ihtis. m mice, the pindiictiou of thiodigb colli.. acid is coiisidciabb i educed and the foim.ition of the \ -; i c e t y I - S s \-dem;. Iacei> I metabolite is mcieased. Ihe higher .t tlrn'iiase activity in mice than in rats accounts tor the grcatci coiivcimoii of thiodigb collie acid mto dithiogh coilic acid w>; tInogly collie acid in the forma species of animal, 'lllnei's (2Yo mice ex acted a proportion of a dose of chloroaeelie acid as unchanged starting acid. Thus, in mice, the metabolic pathway from chloroaeelie acid to thiodigb coilic acid seems to be readily saturable, nossibb on account of an inadequacy in the reacfl^in catalysed by glutathione ,Saeyl transferase, ^^ndcr these ciicumstances. deto\ific;dion of 5 C(CritCCl Wf -vd 'M { ltd Kt ? Se fo/iMv' ' Hiv. i'viv.".u- ^'tl*:<*.{ ;:;ul JilitA.tar'1 ** |W ' I v c i v ?hc M!CMCfH*rt ( [C*sv! 1.1 -viichUnocOHlene .iviyM'AT-UK' c>luhnc 'C- l;il'te I. Kt l.itiu- pr'iJMirtMiii uf producK fnim uiv*;tnitiMn ol ililoroiin lit iicul uml Mtulidene rhloridr m r.its iiiiiI rniei-. X IL-UI >: mct.ibatUf'. ' J . i s f i /1 * {: u ( li'iMii.ui-n ,.o>; V !! 1 \ illU tu . lUo! u!i- XI let* M'. .id- -- i .iku! 1 -ilieis .otiK .i. st X \.iHl (lb .11 ts.V, '..cl?. V Ac*, s 'CHIT K.e. -----X---I'---tiC-!----H--K---J- DhH |: - i.-:; - .! ).ji ; s Jll Jit j ^ ! IA *t s1, t e t' J tv .ik. m ) I fi a b'if 1s \>i[lu ,k 1 b.., |1MV.....:-A.a!tu V Xv.'.'.l Vi.wc.ini- r V ! i!c!Ts.tt)VC ;" dN J 'i Mj ; I. I -die hloroct In lene t'\uie by glutathione S'-epos ide transferase and the modification of i)NA 'i4 by !. I-dtchloioeihylcnc oxide or ehlotoacetyl 6{; chloiidc would be expected to be more significant in Ay mice than m rats. | his diagiK'sis of species su>cep- V* tibihty seems to accord with Maltoni's (2-S) discov- b, cry of vinylidene chloride oncogenicity in (the kid- A ney s of) mice. ... A- , Environmental Health Perspectives v"  \ :n\ ioiouc s I'.Jv'i u!c v :t)c-. dv`s at; ope Ml of U'v , \ V.'! \ ;\'iv . v'tk ipdctiHaf. whivti c.tti LIU'J v<n!\ m ,s sv! <>t b;o!*so ./tm'.siansVs, v\ his h \v <. Stove1 p.-f:.icftnovi uskS iii A !:u il `AO! k |N s O!'! !!!!!!'_ 1 !:C !'..> " Ill.V'Ced All! H k h'lles, ! )i s \ I v . M \\.:!ke. >1" dice his vidtc.o.ah'> Mom1,' i I iioo. s/: ion A".! I*. I Batten. .mo! \|l .able , oiitoNi'rol's am! licit'. KI II KI.M I S ttIVCI'. I am* llaH'.' Os , I) 1 I bo t'to|. >CK a! late IM 1 .It ' of 'Ain 1 . blonde r.`. rctat;o:i to it- n'lu'.vntiiu ( hem Bio!, IntClas! I ! t !'>~'| 2 11 locn, I., c.k! I lathv. ,.\. !i I I he chcmisirv ;uul ",i 'CCltCs'' ot \ 1 ' Cbdvhte' ->i ' I U \ i dlll'lidc III :..ts < he"'. !i! 'i Into.is! !'"ill,~"i ; I 10Oi11: \. 1.1. , O ,i! 1 1.0 ' cHas cincnt leaCtions o! .!ic!uo: .'dieth\ i sulphide .tiiii o! some analogues in .uiueotis so'iipon the isolation ol o'-Clilv'i i'-fl -In olm\\- die.lnisulplude Ii.o's I .oadav S.-v -id ds < 1'fdSi. Dabnt/. b . and Yiuauen. A, I ,S-Vine l-eystein-.S-o\id. cm Homotoges /m Voistale dei trunenireibcmlen Suhsiun/ ti /vstebel. (loom Hoi, 1>X: TSI (I'Xo). Ml Dinnou, H I < the pos-ibje moohanism ot etit- , utogctuc totiou o' 2-d. 2'b i pi-'' .blonde \iin N 'i , \e.ul. Sol. ' (noss. !i . a n d I -cil'nig. .1 /in I colon/ von < !m-i.i:ticlenosid .1 1'i.ik; ( horn '!!, 'ii(> i l`'Vi, Railing. I, , ol .il ! ho mutagenicity of vinyl chloride after metabolic activation, Ambio,*: i`M tld~J). s H.t: bin, \ . o! a! 1 \ ot-"an. ii'M'inc mediated fotmation of .tkvl.itmc ,;ooiti' fiom or.! ho*mule aiul vinyl chloride Ihni !io!ii Biop.bvs lie' 1 omnim !." i4*hil'#7si `I Oiioi-n II , o; ,il \l `.nceim n \ '.tltf .nul poloimal t.n crii-conuiic o' iMiori' -:o! o!!.'. ho'io-. .o a limotion i>t'tno!a- rn'lo .`Cii.iiH1 i.o' HimOIi'. I'h.ii inaov'! 'Hi' l'l~<! s.\ o< < !ov r"i"iio I'-!''" oik! ;ho inoiabi'lom o'l o tin. i i bli'i k'o ( .iiuc: lol'ov' |(*'> r t; >, 11 M., i ,n- i in.I \t..ii|.'nii V Hnniari fa' , i .o. a........... i.. -fi, f* ,! ill':' i/. in..!' . *i! nfi.l Lltki'nb. in o , ;; - !:,r I I ,;,ia r 1^, ij'/ - j. M ,f,o o:;!.' < . : fi M it* li.,billt.:! ' it rn-`i nlr. . .-if. ; i ,, c i *!f. fi * t a-f. tKJt*^v}tr n-i i fit** 1r f'i, !. Kn.fFfiV Kt"` M, ( 1 . l b "A ' dt. .. -.c . . 1.1.:- .'.itiink- .ilnt v \!r.u :b.. . n' himn.lv' J tolcN 'j ; J' w * i. 11 i *!*,,' rf* *{ * >v't fi * t r\<1 Kfl. it.'i U'lfv, U'tv; ,, \ tft. * j ,.fv, 'v,t St.- 1 S S "2 ' P'H 1 .1 I IInbciin.nl. I . Hmt'-oi, II,. ami S.tolo. 1 . 'inti'U ::mi in ( iiinc'c h.mtsioi \"'t icll* by (*-* vinvi cblfTiiic ntoi.i!..>ii;o', c.lil'..">otb;-lone ..' iJt- arul oliii*fi.t.cr.>kScbc4jt' Int, .1. ( ..no; i' ''HilVS 1(. H.iiiin. ,1 K Soiii.i J \ . .in.l I O'miahJ.-\, ). rifiiiic*'{.erC ai.lonti'ino aiul o', inline lio'r.ati'.oo. ItuK-hcrn..BiVipfo.'-iKt'. < iiimrimi -lb ''l~ |f. (noon. I .tin! I f atfi-.'.I), I- vbloii.lo unh i.i'-lno: l)k \ :r ' . Inlet action*' ot oinyi ( Item Bbit Interact In pie", , 1~_ 1 aw lev. H I) . ot a!, Inaettc.inon ot bactcrioph.-i|:e't ~ bv mono- am! ili-tnnciional sulphur niustaids in relation to cross- linkitu: ami ilopnniiatiori ol" bacteriophage DNA. J. Mol. Hiol, to; |s| i|`s.O| IS Kof'oits I I kiii. ioii ,u lit n.i'nttications am! s.incet In Hioti'cv i.i < ,t"Coi. I I Anil'fose and b J..< R* o'. I ds.. I lalste.io! I'.C's. ( Ins hostot. 2nd od . 10, I .'voles', < .oiiot'v a.td Mliod bMeets *'b Alky...tine Agents, Butte:\voi ttis. I oridoii. 1*>V. 2i> Jones. H k.. am! Ilattnvav. IX t I tie tnokigieal fate vinvlulono o."i!.'in!o in i..is, < hem Hml. Interact. In press. 21 \lichaeli'. 1 . ..ml Sclinhoit, M. I' I he reaction ot ii*th>ace- lie acid ''it moutip:.ms and .0111.10' J Biot. ('hem, (Ob', *! i 10.'21 22. Kolbo. II. I mci s.is Innieen itbei .lie bloktodj.se oigantschcr \ orbindiiiicoii. Justus I tobies \mi ( hem (>'*. 2t'" t 2v Walkci. (>. II-. 'mi !latli.va> D I. Hecti.iehefiisc.it analysis ot the [saiboy;. ' 'a ;aliplut!ic-cai'boyvhe acid me* tabolites icsultitig t'lom tracei molecules. Biochem. J. 16~: 5*>5 (l`)7_) 2-1 Mtiltoin, ( Hioeoediivcs o! {lie I AI'HI Intelii.itum.ii l .m- tcicncc. 1 I.iniI'mc: .lann-iv 2m 111 2' .lone'. H k.. .ok! I l.ithw,% . n t . Odlei ernes t'e'V'svr ni ce ami i ..t' it) the tiictabolism v.t vmv hdene s Ho: uic H: I. ( .ttla'i In i'li" y> 'll'm.i.S Met d'oiism ot ch'oivM. ctati toitbinioii'C \vt,i Hh.inn.f l.-sroo! ;o f.-i I R&S 025887 t i i ni.i.|.nihi.r 1 M"