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1 Journal of Korean Association of Cancer Prevention ꁵ 종 설ꁵ 1999; 4(4): Nonsteroidal Antiinflammatory Drugs (NSAIDs) 와암예방 상명대학교생물학과, 1 국립보건원종양연구과 박민선 민병례 남명진 1 Chemopreventive Effects of Nonsteroidal Antiinflammatory Drugs (NSAIDs) Min-Seon Park, Byung-Re Min and Myeong-Jin Nam 1 Department of Biology, Sangmyung University, Seoul and 1 Laboratory of Cancer Research, Department of Biomedical Research, National Institute of Health, Seoul , Korea Nonsteroidal antiinflammatory drugs (NSAIDs) have considerable potential as chemopreventive agents for corolectal cancer. Recent case-control drug surveillance and large cohort studies found that patients with regular aspirin use had a reduced incidence of colorectal cancer and/or decreased death rate from this disease. Several different NSAIDs reduce formation of both colon adenomatous polyps (the precusor lesion of colon cancer) and cancers in experimental animals given known carcinogen. Perhaps most convincing are reports that the NSAID, sulindac promotes regression and inhibits recurrence of adenomatous colon polyps in patients with Familial adenomatous polyposis. The best characterized pharmacological effect of the NSAIDs is their reduction of prostaglandin synthesis by inhibiting prostaglandin synthetase, which catalyzes the formation of prostaglandin precursors from arachidonic acid. Several lines of evidence are contrary to the concept that inhibition of prostaglandin synthesis is central to the NSAIDs' chemopreventive effects. Relatively high levels of prostagalndins have been reported to inhibit tumor cell growth both in vitro and in vivo, andtoinhibit differentiation in some tumor cell lines. Some of the data reviewed here indicate that COX inhibition by NSAIDs is indeed required for their chemopreventive effect. However another body of data make the equally strong case that COX inhibiton is not required for certain presumed chemopreventive effects of NSAIDs. This multiplicity of NSAIDs, if confirmed, could in fact explain their high degree of effectiveness in colon cancer prevention in humans. The great challenge will be to determine which of these or other yet unknown mechanisms produced the remarkable anticancer effect of NSAIDs, as well as the relative contribution of each. If and when these key questions are worked out, then a great deal will have learned about colorectal carcinogenesis. ꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏ Key Words: Nonsteroidal antiinflammatory drugs (NSAIDs), Colorectal cancer, Cyclooxygenase (COX), Prostaglandins (PGs) 책임저자: 남명진, ꂕ , 서울시은평구녹번동 5 번지, 국립보건원특수질환부종양연구과 Tel: , Fax: , Genetx@hanmail.net 본연구는원자력연구개발중장기계획사업(D-4-3) 의지원으로이루어졌음.

2 214 대한암예방학회지: 제 4 권제 4 호 1999 서 Nonsteroidal antiinflammatory drugs (NSAIDs) 는 cyclooxygenase (COX) 의촉매활성을막아아라키돈산(arachidonic acid; AA) 으로부터프로스타글란딘 (prostaglandins; PGs) 을비롯한에이코사노이드 (eicosanoids) 를합성하는기전을억제함으로써염증반응을차단하는소염진통제이다. 따라서 NSAIDs는해열제및진통제로써효과가인정되어널리사용되고있으며, 특히 COX의또다른합성물인 thromboxane의합성도억제하여혈전이생기지않도록함으로써심장병의예방에도이용되고있다. 1) 최근역학조사에의하면 NSAIDs를복용한사람들이결장/ 직장암으로사망할확률이 40~50% 로감소된다는사실이새롭게증명되고있고, 2) 아스피린(ASA) 이나다른 NSAIDs 가결장/ 직장암을억제한다는주목할만한증거들이속속보고되고있어서 3,4) NSAIDs를암예방, 특히결장/ 직장암을중심으로화학적예방에이용하고자하는시도가최근이루어지고있다. 본논문에서는암의효과적인화학적예방을위한여러가지물질가운데, 최근가장활발히연구되어지고있는 NSAIDs의암예방효과와 COX 억제를비롯한암억제기전에대하여현재까지의연구성과와응용가능성을고찰하고자한다. 본 1) NSAIDs 의암예방효과 NSAIDs는 1990년부터암치료및예방의방법으로관심이증폭되었고, 1990년대후반에는많은 in vitro/in vivo 실험의결과그사실이입증되어지고있다. 많은연구의중심이특히결장/ 직장암 (colorectal cancer) 의성장억제에초점이맞추어져이루어지고있는데, 특히결장/ 직장암은 1996년 WHO의통계로볼때, 전세계적으로암으로인한사망의원인가운데 3위를차지하고있으며, 그발생빈도와사망률이점차증가하고있어서이를해결하기위한연구가집중되고있다. 동물실험을통하여얻어진많은가능성을바탕으로하여, 미국을비롯한선진국에서는환자뿐만아니라건강한사람을대상으로하여적정용량의 론 론 일주일에최소한이상을복용하는 NSAIDs를복용하도록한후실제적으로암예방효과 가있는가에관한연구를활발히진행시키고있고, 긍 정적인결과도얻어지고있다. 이와같은연구보고의 중요결론을요약하면다음과같다. (1) NSAIDs의임상연구결과 1 American Cancer Society에의하여주도된연구 에서는 662,424명의성인남녀가연구에참여하였는 데결장/ 직장암발병률이아스피린을정기적으로복용 한그룹에서 40% 의감소를보였다. 하지만아스피 린의정기적인복용이직접적으로작용했는지, 혹은 PGs 의합성을억제함으로써영향을주었는지, 아니면 또다른요인이작용했는지여부는확실히밝혀지지 않았다. 2 스웨덴에거주하고있으면서 NSAIDs를복용하고 있는 11,000명의남녀류마치스성관절염환자를대상 으로조사한결과결장암에걸릴위험도가 37% 정도 감소하였으며, 직장암에걸릴위험도는 28% 낮아졌 3 2회 aspirin 다. 7) 47,000명의건강한전문직종사의남성을대상으로조 사한결과결장/ 직장암에걸릴위험도는 32% 낮아졌 4 65세이상의노인가운데에서 NSAIDs를복용한 다. 8) 사람들은결장/ 직장암의발생률이낮았으며, 복용기간 이 길수록 발생률은 더욱더 낮아졌다. 9) 따라서 NSAIDs의암예방효과에있어서복용기간이중요한 요인이며하루에복용한양은큰의미를주지않음을 시사한다. 5 4개월간 300 mg/day의 sulindac을복용한 FAP 환자에서선종의크기와숫자가감소되었다. 10,11) 6 Piroxicam을하루20 mg씩투여한선종환자에 서직장내 PGs의농도가 50% 감소되었다. (2) 랫드의결장/ 직장암예방효과 Piroxicam, sulindac, sulindac sulfon (exisulind) 등 의 NSAIDs가 azoxymethane (AOM) 으로랫드의결장/ 직장암을유도하는과정에서종양의형성을감소시켜 준다는보고가있는데, 13,14) 특히 Reddy등은 AOM으로 암을유도하는시점을기준으로하였을때, 암유도직 전과실제암이생성되기전인암유도직후 (initiation and postinitiation period) 에 exisulind를미리복용시 켜야만결장/ 직장암의생성을효과적으로억제한다고 하였다. 이때생성된암조직을염색을했을때세포자

3 박민선외 2인: Nonsteroidal Antiinflammatory Drugs (NSAIDs) 와암예방 215 Table 1. Modulating effects of dietary exisulind on apoptosis in colon tumors Experimental group Apoptotic index (%) a ꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏ Control diet 5.33±0.61 c Exisulind, 0.06% b 8.13±0.90 d,1 Exisulind, 0.12% b 9.50±1.20 d,2 Exisulind, 0.12% e 4.37±0.72 ꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏ a Apoptotic index represents the percentage of cells exhibiting apoptosis. b Animals were given exisulind 2 weeks before, during, and after carcinogen treatment and until termination of the study (initiation and postinitiation periods). c Mean±SE (n=10). d Significantly different from the control diet group. 1, p <0.05; 2, p<0.01. e Animals were given exisulind during beginning 14 weeks after the second dose of carcinogen until the end of the study (promotion/progression period) (ref. Reddy et al., Cancer res 1999; 59: ). 연사(apoptosis) 가일어나는세포가유의하게증가된것을확인하였고, exisulind의종양형성억제효과가종양세포의세포자연사유도를통하여일어났음을간접적으로시사하고있다 (Table 1). 14) 일반적으로결장/ 직장암조직내의 PGE 2 의농도가정상조직에비하여높게나타나지만,NSAIDs처리후에는현저히감소하는것이관찰되기때문에 NSAIDs에의한암세포성장억제가 PG의합성을억제함으로써수반되는현상으로일부에서는이해하고있지만, sulindac sufone의경우 NSAIDs에의한 PGs 합성억제현상이일어나지않음에도불구하고, 암을억제하는효과를나타내기때문에 NSAIDs에의한암억제기전이다양함을짐작할수 15 17) 있다. ~ (3) 마우스의폐암예방효과 1998년 Rioux와 Castonguay는 A/J 마우스에 tabacco-specific nitrosamine 4-(methylnitrosamino)- 1-(3-pyridyl)-1-butan one (NNK) 를경구투여하여폐암을유도하였는데, 폐암이유도되기전과폐암이유도되는전과정동안 ASA를처리하였을때 ASA의농도에비례하여폐암의크기가유의하게감소한다는사실을보고하였다. 18) COX-1과 COX-2 활성을모두억제하는 ASA와는달리특이적으로 COX-2의활성만을억제하는 NSAIDs의한종류인 N-[2-(cyclohexyloxy)- 4-nitrophenyl]-methanesulfonamide (NS-398) 를처 리했을때도 ASA 와같은효과를관찰하였다. 이는 NSAIDs에의한종양형성억제과정에표적이되는단계가바로 COX-2의작용단계라는것을의미하는것이며, NSAIDs를이용한암예방을위해서는 COX-2에특이적인약물을사용하여 COX-2의경로를차단해야한다는하나의중요한단서를제공하는것이다. 그외에 COX-2의특이적억제제인 NS-398 사용의장점은 ASA를비롯한다른 NSAIDs보다독성이약하기때문에미래에암예방을위한시도에서독성을최소화하기위한방법으로사용될수있다는점이다. 19,20) (4) 형질전환된마우스유방상피세포의성장억제효과정상조직에비하여암조직에서 COX-2의발현이높다는보고는형질전환된마우스유방상피세포에서도발견되었다. 2122) 이연구는Cornell 의과대학내과팀과 New York의 Strang 암예방센타와의공동연구로이루어진것으로, 형질전환된유방상피세포에서도많은양의PGE 2 가합성되었고,COX-2특이적억제제를사용했을때 PGE 2 가감소됐음을보고하고있다. 특히이연구팀들은COX-2의 promoter와결합하여발현을촉진시키는유전자에관한연구를수행하였는데, 정상적인마우스유방상피조직으로부터분리한 C57/MG 세포주에일시적으로암유전자인 src와 ras를형질도입시켰을때 COX-2 promoter의활성이급격히증가하는것을관찰하였다. 또다른정상상피세포주인 RAC311에 Wnt-1이형질도입된세포주인 RAC/Wnt-1 의 COX-2의활성이원래의 RCC311 세포주와비교하여어떻게변화됐는가를생성된 PGE 2 의농도를측정함으로써간접적으로비교한결과 Wnt-1이도입됨으로써 COX-2 의활성이촉진된다고보고하였다. 위의결과를상고하여볼때, 암을유도하는암유전자가운데특정인자가COX-2 promoter와결합하여 COX-2 의발현을증가시키고, 증가된 COX-2가활성화됨으로써PGE 2 의합성률을높이는과정이암을유발하는한기전으로생각되며, 이와같은기전으로유도된암을치료함에있어서 NSAIDs를이용하여암의유도를차단하는것이최선의방법이다. 2) NSAIDs 의암억제기전 위의내용을살펴보았을때, 일반적으로 NSAIDs의암억제효과가 COX의활성과 PGs의합성을억제함으로써나타난다는결론을유추하고있다. 하지만 COX의

4 216 대한암예방학회지: 제 4 권제 4 호 1999 활성억제와는다른기전을통하여화학적예방효과가일어나는가설도임상적으로나실험적으로일부증명되고있다. 이에관하여 Zhang등은 The Journal of Experimental Medicine에서 NSAIDs의화학적예방효과가 COX와는관계없이일어난다는또다른증거를제시하고있다. 15) COX-1 또는 COX-2, 아니면두효소모두결핍되어있는섬유모세포를암유전자인 ras 와 SV-40를이용하여형질전환시킨후만든세종류의세포주각각에 NSAIDs를처리하여그결과를관찰하였다. 세세포주모두여러 NSAIDs에의하여세포의성장이억제되었고, 세포자연사가유도되었다. 이때사용된 NSAIDs는특이적으로 COX- 2의활성을억제해주는 NS-398 뿐아니라비특이적인 NSAIDs 등이사용됐는데, 그결과는모두같았다. 따라서 NSAIDs에의하여유도되는현상들이단순히 COX를억제함으로써나타나는결과가아니라는점을인식할수있고, 이와유사한결과는인간의결장/ 직장암세포에서도관찰한보고도있었다. 16,17) Shiff등은 COX-1과 COX-2 의기능이없어서 PGs를합성하지못하는직장결장암세포인 HCT-15와이두기능을모두가지고있는 HT-29 세포주를이용하여 NSAIDs가세포의성장과세포자연사에미치는효과를보았다. 이들역시두세포모두에서세포성장의억제와세포자연사를관찰함으로써 NSAIDs에의한화학적예방효과가 COX와관련된기전뿐아니라 COX와는독립적인다른기전이존재할것이라는가능성을높여주었다. 이와같이아직밝혀지지않은또다른기전과, 그때작용하는단백질들이암형성억제에있어서제공해줄무한한가능성때문에많은연구실에서는그것들을밝히기위한연구가활발히진행되고있다. 이에관련된NSAIDs의암억제기전에관한몇몇보고들을아래와같이정리하여보았다. COX와의관련성을기준으로하여크게 3개의중요한카테고리로나뉘어있다: (i) COX 와연관된기전, (ii) COX와독립적인기전, (iii) 아직 COX에대하여독립적인작용인지증명되지않은기전. (1) COX와연관된기전결장/ 직장암의형성에있어서 COX와 PGs가중요한역할을할것이라는가정은다음과같은사실에근거하여유도되었다:(a) 결장/ 직장암에서의 PGE 2 의수치가정상조직보다높게나타났고; (b) PGs를포함한에이코사노이드가대장점막세포의성장을촉진하고, 세 포자연사를감소시켰으며; (c) 결장/ 직장에생성된종양에서 COX-2 가과발현됐으며, 선종보다는악성종양에서발현이더많이됐다; (d) COX-2가 Apc 유전자결핍마우스의결장/ 직장암유도를촉진한다. 23) 에이코사노이드를합성하는것외에 COX는그자체의 peroxidase 기능을이용하여발암물질(car- cinogen) 을활성화시키거나, 직접적인돌연변이원으로작용하는 malondialdehyde나 peroxyl radical을생성하여암형성을촉진하는역할도한다(fig. 1). 발암과정에중요한혈관신생역시 PGs, COX와관련이있는데, PGE 2 와 COX-2 가혈관신생을촉진하고, 24) 반대로 NSAIDs 가이현상을억제한다. 25) 하지만 sulindac sufone 역시혈관신생을억제한다는보고도있는점으로미루어볼때, 26) 혈관신생역시 PGs 혹은 COX와는독립적기전에의할수도있다는가능성을시사하고있다. 비록 COX 나에이코사노이드가결장/ 직장의암유발에꼭필요한것인가하는문제는완전히증명되지는않았고,COX나 PGs없이도암이유발될수있다는여러보고도나오고있지만, 현재까지는결장/ 직장암에있어서 COX가중심을차지하고있다는사실을부정할수는없다. (2) COX와독립적인기전 1 세포주기의전환 (Cell turnover) : 모든조직이구조적으로안정된상태를유지하기위해서는조직을구성하고있는세포의생성과사멸이제대로조절되어야한다. 산발성결장/ 직장선종과선암종에서는세포자연사가억제되어있다가 sulindac을처리하면선종의크기와수가감소되는데, 3) 특히조직이나종양의성장속도가구성세포들의증식률과손실률의비로결정된다는사실을고려하여볼때, NSAIDs가세포의 kinetics를조절하여암억제효과를나타낼것이라는가능성은매우높아진다. NSAIDs가대장점막세포의세포주기를정지상태로유도하거나, 세포주기를조절하는몇몇중요한분자들의수준을감소시킴으로써세포의성장을억제한다는보고가 16,17) 이와같은가설을뒷받침하기는하지만정확한분자기전은아직까지확실히밝혀지지않았다. 또다른연구팀들은 NSAIDs의효과를다른기전으로해석하고있는데, sulindac sulfone이 cgmpdependent phosphodiesterase를억제함으로서세포사를유도한다는가정과 27) NSAIDs의처리로세라미드 (ceramide) 가생성된다고하는의견이바로그것이

5 박민선외 2인: Nonsteroidal Antiinflammatory Drugs (NSAIDs) 와암예방 217 Fig. 1. Arachidonic acid metabolism by COX isoenzymes. Phospholipase A 2 (PLA 2) releases arachidonic acid (AA) from membrane phospholipids, which is in turn converted by either COX-1 or COX-2 to PGG 2 (C, cyclooxygenase catalytic activity of COX) and then to PGH 2 (P, peroxydase catalytic activity of COX). PGH 2 is converted to either PGs (e.g., E 2,F 2α, I 2,D 2); thromboxane A 2 (TxA 2); or malondialdehyde (MDA). MDA is a direct-acting mutagen and carcinogen and can be produced without COX by direct lipid peroxidation. AA can be converted directly to 15-(R)-HETE by both COX isoenzymes. COX- 1 is constitutively expressed in most tissues, whereas COX-2 is induced by cytokines, growth factors, tumor promoters, or other agents after the initiation of specific physiological events. Compounds other than PGG 2, e.g., procarcinogenic hydroperoxides, can serve as substrates for the peroxidase activity of COX enzymes. Inactive carcinogens serving as electron acceptors can also became activated by this activity. The COX isoenzymes are also involved in the formation of peroxyl radicals that can activate procarcinogens. 43) 다. 28) NSAIDs가 COX의작용을억제하여 PGs의생성이줄어들면, 상대적으로세포내의아라키돈산의양이많아지게되는데, 이로인하여중성의 sphingomyelinase 가활성화되어스핑고미엘린(sphingo- myelin) 을세라미드로전환한다는것이다(Fig. 2). 2 세포의형질전환 (Cell transformation): Zhang 등의발표이외에도 NSAIDs가세포의형질전환을억제시킨다는연구논문들은많이보고되고있다. 1997년에 Dong등은마우스의상피세포인 JB6 세포에 phorbol ester (TPA) 를처리하여형질전환을유도하는과정이 salicylates 에의하여억제된다고하였다. 29) 이효과는 Fig. 2. Model relating AA and ceramide to colorectal cancer chemoprevention. Mutation of the APC gene initiates colorectal tumorigenesis and results in abnormally decreased apoptosis. Perturbation of lipid metabolism by pharmacological, dietary, or genetic means can partially correct the deficits. AA is generated by cytosolic and secreted phospholipase A2, which hydrolyzes plasma membrane lipids or lipids derived from the diet. AA is normally used as a substrate by the COXs to produce eicosanoids such as prostaglandins. NSAIDs inhibit the activity of the COXs, which increases the cellular pool of AA. AA stimulates neutral sphingomyelinase activity, which catalyzes the hydrolysis of sphingomyelin to generate ceramide. Ceramide acts as second messenger that activates the cellular apoptotic machinery. The Mom1 gene is a modifier of polyp formation in the Min mouse, a model for APC mutation-induced colon tumors. The Mom1 gene encodes a secreted phospholipase A2, an enzyme predicted to increase the level of free AA. Inactivating mutations in Mom1 predispose Min mice to developing intestinal polyps and would be expected to result in reduced levels of AA. This in turn could result in decreased production of ceramide and therefore a relative resistance to programmed cell death and increased tumor susceptibility. The lipid compositions of diets are known to affect colon cancer risk. Diets rich in unsaturated fatty acids such as AA are associated with a decreased incidence of colon cancer. This effect could be due to increased levels of AA and subsequent increased susceptibility to apoptosis as described above. 28) AP-1의활성화가중요한작용을하는데, 인도메타신 (indomethacin) 을처리하여도TPA에의한형질전환이나 AP-1 의활성화가모두억제되지않기때문에,

6 218 대한암예방학회지: 제 4 권제 4 호 1999 Table 2. Mechanisms influenced by NSAIDs that may contribute to their antineoplastic effects COX-dependent COX-independent COX-dependence unclear ꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏ Cell turnover Cell turnover Tumor immunity proliferation/apoptosis proliferation/apoptosis Myc transcription Carcinogen formation Cell transformation PPAR activation Angiogenesis DNA repair Angiogenesis Ras signal transduction MAP kinase activation NF-κB activation ꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏ The Table shows the cellular or molecular mechanisms influenced by NSAIDs that may contribute to their antineoplastic effects, classified in relation to their dependence on inhibition of cyclooxygenase catalytic activity. 43) NSAIDs에의한형질전환억제과정을 PGs의합성과는독립된기전이라고해석하고있다. 이듬해인 1998 년에는 Hermann등도마우스의섬유모세포가 H-ras와 SV40에의하여형질전환되는과정이 sulindac sulfide 에의하여억제되는것으로보고하였다. 30) Hermann등은sulindac sulfide의이효과가ras signaling을직접억제함으로써나타난다고설명하고있는데, sulindac sulfide가 Ras와비공유적으로결합을함으로써 Ras와의존적으로연관된 Raf와의결합이나 Raf의활성화단계를억제한다는것이다. Ras는이와같이형질전환과정에서작용하는것외에도 NSAIDs에의한암억제에있어서다른작용기전에도영향을미치는데, 아라키돈산과 PGs가 p120gap과 NF-1GAP과같은 Ras 조절단백질을조절하기때문에 NSAIDs에의하여 Ras 의활성화가조절되는것이에이코사노이드경로와도관련이있다. 31) 3 DNA Repair: ASA와 nonsalicylate NSAIDs는 DNA mismatch repair 가결실되어생긴결장/ 직장암세포(i.e., HCT-116, HCT-15, SW48, LoVo) 에서 microsatellite instability 를감소시킨다. 32) 이런세포들은대개 hmlh1, hmsh2, 혹은 hmsh6같은유전자의돌연변이를가진것으로 NSAIDs를처리했을때세포자연사를일으켜사멸된다. HCT-15세포주는 COX가발현되지않는세포임에도불구하고 NSAIDs에의한세포자연사가유도되는점으로미루어볼때, COX와독립적인기전에의하여일어난다는것을시사한다. 4 MAP Kinase: Salicylic acid (SA) 는섬유아세포인 FS-4에서 p38 MAP kinase의활성화와세포자연사를 유도하는데, p38 MAP kinase inhibitor인 SB 을처리하면이두과정이모두억제된다. 33) p38 MAP kinase의활성이 SA에의한 NF-kB 억제에중요한작용을하는것으로생각된다. 5 NF-kB: 인도메타신과는달리 ASA와 SA는 NF-kB 의활성을억제하는데, 이는 ASA나 SA가 IkB kinaseβ와결합하여 IkB의분해를못하게함으로써 NF-kB 가핵내로이동하지못하게되고, 따라서 NF-kB에의하여조절되었던여러유전자의발현의발현이차단됐기때문이다. 33,34) NF-kB는세포의종류와환경여건에따라세포자연사를유도하기도하고억제하기도하는데, 랫드섬유모세포의 ras-형질전환이 ASA에의하여차단되는것도 NF-kB의활성이억제됐기때문이다. 35) (3) 그외의기전여기에해당되는가설들은 PGs 혹은 COX의억제와는관련이없는듯보이지만, 아직까지 COX가결핍되어있거나,PGs가합성되지않는세포와연관된자세한연구가이루지지않았기때문에실제적으로 COX 혹은아라키돈산대사작용과어떤관련이있는지는확실치않다. 1997년에 Lu 등이보고한바에따르면, 혈청을넣지않고키운계태아섬유모세포에 NSAIDs를처리하거나 pp60 v-sac 을활성화시켰을때, 세포자연사가유도되면서 myc의발현이급격히증가한다고하였고, antisense myc을처리하면다시세포자연사가억제된다고하였다. 36) 다른암세포주에서도이와유사한결과가보고되면서 NSAIDs에의한세포자연사유도가 myc

7 박민선외 2인: Nonsteroidal Antiinflammatory Drugs (NSAIDs) 와암예방 219 과연관된다는가능성을시사하고있다. Peroxisomal proliferator-activated receptors (PPARs) 는 nuclear hormone receptor protein의전사를조절하는 factor 의한그룹으로, 자극에따라섬유모세포를 adipocyte 로유도한다. PPAR-γ 수용체가대장에서많이발현되는데, 특히대장암세포에서는더많은양의수용체가발현되는것으로밝혀졌다. 37) In vitro에서는대장암세포의 PPARs가활성화될때성장속도와분화정도가감소하며, 전부는아니지만, 인도메타신이나일부선택적인 NSAIDs와결합하여 PPAR-γ 수용체가활성화된다는사실이알려졌다. 38) 하지만 piroxicam 과같이결장/ 직장암의용종을감소시켜주는 NSAIDs도 PPAR-γ와결합하지않고, troglitazone과같은ppar-γ의활성화제가 Apc min/+ 마우스에서오히려종양을증가시킨다는보고도 39,40) 함께알려져있기때문에실제로 PPAR의활성화가 NSAIDs의암억제효과와관련이있는지는아직알수없다. 일반적으로종양은전체조직가운데면역체계의통제로부터벗어나있는것으로알려져있는데, 이는종양과관련된항원을감지하는기작이방해받고있기때문이다. 이과정에는항원제시(antigen presentation) 를담당하는 class I과 II HLA가중요한역할을하는데, 암유발원을처리한랫드의직장의점막에서 MHC 유전자의발현이 piroxicam에의하여증가하는것으로보고되었다. 3) PGE 2 는 HLA class II의발현을감소시키고, NSAIDs는이와는반대로증가시킨다는연구결과등이 41) 아마도 COX와는독립적으로나타나는NSAIDs 의또다른암억제효과일것으로사료된다. 결 앞에서간략하게설명한바대로 NSAIDs의암예방효과는여러단계를통하여나타남을알수있었다 (Table 2). 일부연구결과를토대로보면, NSAIDs가암예방효과를나타내기위해서는 COX를억제하는것이필수적인단계임을시사하지만, 또다른연구결과는 NSAIDs가 COX와는별개의기전에의하여같은효과를나타내는것을보여주고있다. 이와같이외견상서로일치하지않는결과는단순히이론적인관심이다를뿐아니라사실뿐아니라결장/ 직장암예방을위한 론 전략적인계획을세우거나, 발암과정(carcinogenesis) 에있어서관련된기전을연구하기위한방향을잡는데도중요한문제를내포할수있을것이다. 하지만아마도이런사실은전혀논쟁할필요가없을는지도모른다. 오히려 NSAIDs가 COX-dependent한경로와 COX-independent 한경로를통하여결장직장암의화 / 학적예방효과를나타낸다면, 우리는이두경로가다단계의결장직장의발암과정중각각다른단계에적 / 용되도록하는새로운모델을설정할수도있을것이다. 42) NSAIDs의다양한효과들이제대로확증된다면사람의결장/ 직장암예방에있어서높은효율이잘설명될것으로믿는다. 많은의미있는시도들이 NSAIDs의암예방효과를나타내는뚜렷한경로를밝힐뿐아니라각경로들이의미하는중요성도밝힐수있을것으로기대되며, 이와같은의문이해결되면발암과정과관련된많은정보를얻는것을물론이고, 통상적으로사용되었던 NSAIDs보다도더안전하며효과가높은새로운물질도발견되어획기적인치료방법으로사용될수있을것이다. 참고문헌 1) Koudstaal PJ. Stroke prevention: which drugs to use and when? J Neurol 1999; 246: ) Smally W, Dubois RN. Colorectal cancer and non steroidal anti-inflammatory drugs. Adv Phamacol 1997; 39: ) Schiff SJ, Rigas B. Nonsteroidal anti-inflammatory drugs and colorectal cancer: evolving concepts of their chemopreventive actions. Gastroenterology 1997; 113: ) Takayama T, Katsuki S, Takahashi Y, Ohi M, Nojiri S, Sakamaki S, Kato J, Kogawa K, Miyake H, Niitsu Y. Aberrant crypt foci of the colon as precusors of adenoma and cancer. N Engl J Med 1998; 339: ) Thun MJ, Namboodiri MM, Health CW Jr. Aspirin use and reduced risk of fatal colon cancer. NEnglJMed 1991; 325: ) Thun MJ, Namboodiri MM, Calle EE, Flanders WD, Heath CW Jr. Aspirin use and risk of fatal cancer. Cancer Res 1993; 53: ) Gridley G, McLaughlin JK, Ekbom A, Klareskog L, Adami HO, Hacker DG, Hoover R, Fraumeni JF Jr. Incidence of cancer among patients with rheumatoid

8 220 대한암예방학회지: 제 4 권제 4 호 1999 arthritis. J Natl Cancer Ins 1993; 85: ) Giovannucci E, Rimm EB, Stampfer MJ, Colditz GA, Ascherio A, Willett WC. Aspirin use and the risk for colorectal cancer and adenoma in male health professionals. Ann Intern Med 1994; 121: ) Smalley W, Ray WA, Daugherty J, Griffin MR. Use of nonsteroidal anti-inflammatory drugs and incidence of colorectal cancer: a population-based study. Arch Intern Med 1999; 159: ) Labayle D, Fischer D, Vielh P, Drouhin F, Pariente A, Bories C, Duhamel O, Trousset M, Attali P. Sulindac cause regression of rectal polyps in familial adenomatous polyposis. Gastroenterology 1991; 101: ) Giardiello FM, Hamilton SR, Krush AJ, Piantadosi S, Hylind LM, Celano P, Booker SV, Robinson CR, Offerhaus GJ. Treatment of colonic and rectal adenomas with sulindac in familial adenomatous polyposis. N Engl J Med 1993; 328: ) Earnest DL, Hixon LJ, Fennerty MB. Inhibition of prostaglandin systhesis: potential for chemoprevention of human colon cancer. Cancer Bulletin 1991; 43: ) Alberts DS, Hixson L, Ahnen D, Bogert C, Einspahr J, Paranka N, Brendel K, Gross PH, Pamukcu R, Burt RW. Do NSAIDs exert their colon cancer chemoprevention activities through the inhibition of mucosal prostaglandin systhetase? J Cellular Biochem 1995; Supplement 22: ) Reddy BS, Kawamori T, Lubet RL, Steele VE, Kelloff GJ, Rao CV. Chemopreventive efficacy during carcinogenic process. Cancer Res 1999; 59: ) Zhang X, Morham SG, Langenbach R, Young DA. Malignant transformation and antineoplastic actions of nonsteroidal antiinflammatory drugs (NSAIDs) on cyclooxygenase-null embryo fibroblasts. J Exp Med 1999; 190: ) Shiff SJ, Qiao L, Tsai LL, Rigas B. Sulindac sulfide, and aspirin-like compound, inhibits proliferation, cause cell cycle quiescence, and induces apoptosis in HT-29 colon adenocarcinoma cell. J Clin Inves 1995; 96: ) Shiff SJ, Koutsos MI, Qiao L, Rigas B. Nonsteroidal antiinflammatory drugs inhibit the proliferation of colon adenocarcinoma cells: effects on cell cycle and apoptosis. Exp Cell Res 1996; 222: ) Rious N, Castonguay A. Prevention of NNK-induced lung tumorigenesis in A/J mice by acetylsalicylic acid and NS-398. Cancer Res 1998; 58: ) IARC. Handbooks of cancer prevention. Nonsteroidal anti-inflammatory drugs. IARC Sci Publ. 1997; 1: ) Arai I, Hamasaka Y, Futaki N, Takahashi S, Yoshikawa K, Higuchi S, Otomo S. Effect of NS-398, a novel non-steroidal anti-inflammatory agent on gastric ulceration and acid secretion in rats. Res Commun Chem Pathol Pharmacol 1993; 81: ) Subbaramaiah K, Tekang N, Ramonetti JT, Araki R, DeVito B, Weksler BB, Dannenberg AJ. Transcription of cyclooxygenase-2 is enhanced in transformed mammary epithelial cells. Cancer Res 1996; 56: ) Howe LR, Subbaramaiah K, Chung WJ, Dannenberg AJ, Brown AMC. Transcriptional activation of cyclooxygenase-2 in Wnt-1-transformed mouse mammary epithelial cells. Cancer Res 1999; 59: ) Oshima M, Dinchuk JE, Kargman SL, Oshima H, Hancock B, Kwong E, Trzaskos JM, Evans JF, Taketo MM. Suppression of intestinal polyposis in ApcΔ716 knockout mice by inhibition of cyclooxygenase 2 (COX-2). Cell 1996; 87: ) Tsujii M, Kawano S, Tsuji S, Sawaoka H, Mori M, Dubois RN. Cyclooxygenase regulates angiogenesis induced by colon cancer cells. Cell 1998; 93: ) Peterson HI. Tumor angiogenesis inhibition by prostaglandin synthetase inhibitors. Anticancer Res 1986; 6: ) Skopinska-Rozewska E, Piazza GA, Sommer E, PamukcuR,BarczE,FilewskaM,KupisW,CacanR, Rudzinski P, Bogdan J, Mlekodaj S, Sikorska E. Inhibition of angiogenesis by sulindac and its sufone metabolite (FGN-1): a potential mechanism for their antineoplastic properties. Int J Tissue React 1998; 20: ) Piazza GA, Li H, Liu L, Sperl G, Pamukcu R, Thompson WJ, Ahnen DJ. Cyclic GMP (CG) phosphodiesterase (PDE) inhibition: a novel mechanism for the antineoplastic properties of exisulind. Gastroenterology 1999; 116: A ) Chan TA, Morin PJ, Vogelstein B, Kinzler KW. Mechanisms underlying nonsteroidal antiinflammatory drugmediated apoptosis. Proc Natl Acad Sci USA 1998; 95: ) Dong Z, Huang C, Brown RE, Ma WY. Inhibition of activator protein activity and neoplastic transformation by aspirin. J Biol Chem 1997; 272: ) Hermann C, Block C, Geisen C, Haas K, Weber C, Winde G, Möröy, Müller O. Sulindac sulfide inhibits Ras signaling. Oncogene 1998; 17: ) Han J-W, McCormick F, Macara IG. Regulation of ras-gap and the neurofibromatosis-1 gene product by eicosanoids. Science 1991; 252:

9 박민선외 2인: Nonsteroidal Antiinflammatory Drugs (NSAIDs) 와암예방 ) Rüshoff J, Wallinger S, Dietmaier W, Bocker T, Brochoff G, Hofstadter F, Fishel R. Aspirin suppresses the mutator phenotype associated with hereditary nonpolyposis colorectal cancer by genetic selection. Proc Natl Acad Sci USA 1998; 95: ) Schwenger P, Alpert D, Skolnik EY, Vilcek J. Activation of p38 mitogen-activated protein kinase by sodium salicylate leads to inhibition of tumor necrosis factor-induced IkBα phosphorylation and degrada- tion. Mol Cell Biol 1998; 18: ) Yin MJ, Yamamoto Y, Gaynor RB. The anti-inflammatory agents aspirin and salicylate inhibit the activity of IkB kinase- β. Nature 1998; 396: ) Ljungdahl S, Shoshan MC, Linder S. Inhibition of the growth of 12 V-ras-transformated rat fibroblasts by acetylsalicylic acid correlates with inhibition of NFkB. Anti-Cancer Drugs 1997; 8: ) Lu X, Fairbairn DW, Bradshaw WS, O'Neill KL, Ewert DL, Simmons DL. NSAIDs-induced apoptosis in Rous sarcoma virus-transformed chicken embryo fibroblasts is dependent on v-src and c-myc and is inhibited by bcl-2. Prostaglandins 1997; 54: ) DuBois RN, Gupta R, Brockman BS, Reddy B, Krakow SL, Lazar MA. The nuclear eicosanoid receptor, PPAR γ, is aberrantly expressed in colonic cancers. Carcinogenesis 1998; 19: ) Lehmann JM, Lenhard JM, Oliver BB, Ringold GM, Kliewer SA. Peroxisome proliferator-activated receptors alpha and gamma are activated by indomethacin and other non-steroidal anti-inflammatory drugs. J Biol Chem 1998; 272: ) Saez E, Tontonoz P, Nelson MC, Alvarez JG, Ming UT, Baird SM, Thomazy VA, Evans RM. Activators of the nuclear receptor PPAR-gamma enhance colon polyp formation. Nat Med 1998; 4: ) Lefebnre A-M, Chen I, Desreumaux P, Najib J, Fruchart J-C, Geboes K, Briggs M, Heyman R, Auwerx J. Activation of the peroxisome proliferator-activated receptor gamma promotes the development of colon tumors in C57BL/6J-APC MIN /+mice. Nat Med 1998; 4: ) Arvind P, Papavassiliou ED, Tsioulias GJ, Qiao L, Lovelace CIP, Rigas B. PGE 2 down-regulates the expression of HLA-DR antigen in human colon adenocarcinoma cell lines. Biochemistry 1995; 34: ) Rigas B, Shiff SJ. Is inhibition of cyclooxygenase required for the chemopreventive effect of NSAIDs in colon cancer? A model reconcilling the current contradiction. Med Hypotheses. In press. 43) Shiff SJ, Rigas B. The role of cyclooxygease inhibition in the antineoplastic effects of nonsteroidal antiinflammatory drugs (NSAIDs). J Exp Med 1999; 190: