• 대한의생명과학회지
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• 제24권3호
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• pp.143-149
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• 2018

Excessive exposure to estrogens is the most important risk factor for the development of hormone-sensitive cancers, especially breast cancer. Estrogen stimulates the expression of genes and proteins involved in cell proliferation by binding to estrogen receptor (ER). Another possible mechanism of ER-independent carcinogenicity of estrogens is based on the hydroxylation of estradiol resulting in the formation of catechol estrogens. Catechol estrogen 4-hydroxyestradiol ($4-OHE_2$) is further oxidized to catechol estrogen-3,4-quinones, the major carcinogenic metabolites of estrogens. Evidence increasingly supports the critical role of $4-OHE_2$ in hormonal carcinogenesis via DNA adduct formation or production of reactive oxygen species, which finally contribute to the transformation of normal mammary epithelial cells and the enhanced growth of breast cancer cells. It is also reported that the level of $4-OHE_2$ or its quinones is highly up-regulated in urine or tissues of breast cancer patients. Thus, we highlight the oncogenic roles of $4-OHE_2$ in catechol estrogen-induced breast carcinogenesis.

• 대한의생명과학회지
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• 제25권1호
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• pp.1-6
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• 2019

The hydroxylation of estradiol results in the formation of catechol estrogens such as 2-hydroxyestradiol ($2-OHE_2$) and 4-hydroxyestradiol ($4-OHE_2$). These catechol estrogens are further oxidized to quinone metabolites by peroxidases or cytochrome P450 (CYP450) enzymes. Catechol estrogens contribute to hormone-induced carcinogenesis by generating DNA adducts or reactive oxygen species (ROS). Interestingly, many of the natural products found in living organisms have been reported to show protective effects against carcinogenesis induced by catechol estrogens. Although some compounds have been reported to increase the activity of catechol estrogens via oxidation to quinone metabolites, many natural products decreased the activity of catechol estrogens by inhibiting DNA adduct formation, ROS production, or oxidative cell damage. Here we focus specifically on the chemopreventive effects of these natural compounds against carcinogenesis induced by catechol estrogens.

• Journal of Ginseng Research
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• 제13권1호
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• pp.37-41
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• 1989

Benzo(a)pyrene(BP)의 monooxygenase(AHH)에 의해서 생성된 반응성 대사물질들의 in vitro DNA와의 결합 및 BP 대사에 관여하는 효소들의 활성도에 미치는 인삼 물추출물의 영향을 조사하였으며, DNA-BP metabolite adduct들은 Sephadex LH-20 column으로 chromatography하여 5개의 major peak 들을 얻었다. 이 peak 들을 극성이 큰 순서대로 A부터 E까지 임의로 정하고 5개의 peak들을 7,8-diol-9,10-oxide(A), 7,8-oxide(B). 4,5-oxide(C), 9-HO-BP(D & E) adduct들로 잠정적으로 확인하였다. Peak A, C, D 그리고 E는 각각 대조군의 30, 15, 20 그리고 30%로 감소되었으며 peak B는 의미있는 변화를 보이지 않았다. DNA-BP 결합 억제와 관련하여 in vitro와 in vivo 투여시의 경향이 유사하여 EH의 활성도만 BP투여 대조군보다 38%정도 의미있게 유도되었다.

• Archives of Pharmacal Research
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• 제22권5호
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• pp.474-478
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• 1999

Modulation of unscheduled DNA synthesis by dehydroepiandrosterone (DHEA) after exposure to various chemical carcinogens was investigated in the primary rat hepatocytes. Unscheduled DNA synthesis was induced by treatment of such direct acting carcinogens as methly methanesulfonate (MMS) and ethyl methanesulfonate (EMS) or procarcinogens including benzo(a)pyrene (BaP) and 7, 12-dimethylbenz(a)anthracene (DMBA). Unscheduled DNA synthesis was determined by measuring [methyl-3H]thymidine radioactivity incorporated into nuclear DNA of hepatocytes treated with carcinogens in the presence or absence of DHEA. Hydroxyurea $(5{\times}10^{-3} M)$was added to growth medium to selectively suppress normal replication. DHEA at concentrations ranging from $(1{\times}10^{-6} M)$ to$(5{\times}10^{-4} M)$ did not significantly inhibit unscheduled DNA synthesis induced by either MMS $(1{\times}10^{-4} M)$ or EMS $(1{\times}10^{-2} M)$. In contrast, DHEA-significantly inhibited unscheduled DNA synthesis induced by BaP $(6.5{\times}10^{-5} M)$ and DMBA.$(2{\times}10^{-5} M)$. DHEA-induced hepatotoxicity in rats was examined using lactate dehydrogenase (LDH) release as an indicator of cytotoxicity. DHEA exhibit no significant increase in LDH release compared with the control at 18 h. These data suggest that nontoxic concentration of DHEA does not affect the DNA excision repair process, but it probably influence the enzymatic system responsible for the metabolic activation of procarcinogens and thereby decreases the amount of the effective DNA adducts formed by the ultimate reactive carcinogenic species.

• Archives of Pharmacal Research
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• 제25권1호
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• pp.11-24
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• 2002

The antitumor antibiotic (+)-CC-1065 can alkylate N3 of guanine in certain sequences. A previous high-field $^1H$ NMR study on the$(+)-CC-1065d[GCGCAATTG*CGC]_2$ adduct ($^*$ indicates the drug alkylation site) showed that drag modification on N3 of guanine results in protonation of the cross-strand cytosine [Park, H-J.; Hurley, L. H. J. Am. Chem. Soc.1997, 119,629]. In this contribution we describe a further analysis of the NMR data sets together with restrained molecular dynamics. This study provides not only a solution structure of the (+)-CC-1065(N3- guanine) DNA duplex adduct but also new insight into the molecular basis for the sequence- specific interaction between (+)-CC-1065 and N3-guanine in the DNA duplex. On the basis of NOESY data, we propose that the narrow minor groove at the 7T8T step and conformational kinks at the junctions of 16C17A and 18A19T are both related to DNA bending in the drugDNA adduct. Analysis of the one-dimensional $^1H$ NMR (in $H_2O$) data and rMD trajectories strongly suggests that hydrogen bonding linkages between the 8-OH group of the (+)-CC-1065 A-sub-unit and the 9G10C phosphate via a water molecule are present. All the phenomena observed here in the (+)-CC-1065(N3-guanine) adduct at 5'$-AATTG^*$are reminiscent of those obtained from the studies on the (+)-CC-1065(N3-adenine) adduct at $5'-AGTTA^*$, suggesting that (+)-CC-1065 takes advantage of the conformational flexibility of the 5'-TPu step to entrap the bent structure required for the covalent bonding reaction. This study reveals a common molecular basis for (+)-CC-1065 alkylation at both $5'-TTG^*$ and $5'-TTA^*$, which involves a trapping out of sequence-dependent DNA conformational flexibility as well as sequence-dependent general acid and general base catalysis by duplex DNA.

• 한국식품과학회지
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• 제33권6호
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• pp.656-663
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• 2001

본 연구는 흡연에 의해 체내로 유입된 독성 물질들로 유발될 수 있는 폐암을 비롯한 각종 질병 기전을 in vitro 상에서 재현한 실험적 모델을 이용하여 8개의 식물로부터 추출한 phyto-extract mixture의 작용에 의하여, 체내 니코틴이 니트로사민으로의 전환되는 대사효율과 NNK의 활성화에 미치는 효과를 분석한 것이다. 이를 위해 in vitro 상에서 phyto-extract mixture에 의한 니트로소모폴린의 생성 억제와 CYP효소 활성 억제를 분석하였다. Phyto-extract mixture에 의한 니코틴으로부터 니트로소모폴린이 생성되는 대사 억제능 실험 결과, phyto-extract mixture(75%)는 비타민 C(64%)와 가루녹차(37%) 보다 우수한 억제 효능을 나타내므로서, phyto-extract mixture는 니코틴으로 부터 유독한 중간 대사물질이 생성되는 경로를 효과적으로 억제시킬 수 있음을 알 수 있었다. 또한 간에서 NNK 활성화에 관여하는 CYP 효소들에 대한 phyto-extract mixture의 효소 활성 억제능 분석 결과, phyto-extract mixture이 가루녹차보다 NNK로부터 발암물질이 생성되는 경로를 효과적으로 억제시키는 것으로 분석되었다. 결론적으로 phyto-extract mixture는 흡연으로 체내에 유입된 니코틴이 NNK와 같은 강력한 발암 물질인 니트로사민 유도체로 전환되는 경로를 효과적으로 억제함으로써 암 발생율을 효과적으로 낮출 수 있는 기능성 첨가제 혹은 식 음료로 활용될 수 있음을 in vitro 실험으로 증명하였다.

• Toxicological Research
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• 제16권3호
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• pp.221-227
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• 2000

A 6-sulfooxymethylbenzo[a]pyrene (SMBP), the ultimate metabolite of methyl-substituted benzo[a]pyrene (BP), has been found to be carcinogenic in mice. These properties may be attributable to its strong reactivity with cellular macromolecules such as DNA. However, serum and its major constituent albumin attenuated significantly the cytotoxicity and mutagenicity of 5MBP in bacterial and mammalian cell systems. This inhibitory activity of serum against 5MBP-induced cytotoxicity and mutagenicity in Chinese hamster V79 cells appears to be caused by the reduced macromolecular adducts such as DNA and proteins, but serum failed to reduce 5MBP binding to naked calf thymus DNA. A number of proteins in the serum could act as nucleophiles that are able to intercept reactive chemicals through covalent binding. Albumin present in the plasma seems to be one of major components responsible for direct binding with 5MBp, thereby reducing its reactivity to genetic materials. We here determined which fraction is preferential for 5MBP binding through fractionation of 5MBP-treated serum with ammonium sulfate. The albumin-containing fraction had slightly more affinity for 5MBP than the immunoglobulin-containing fraction. Our results indicate that the covalent modification of plasma proteins may reduce 5MBP-induced damage.

• IMMUNE NETWORK
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• 제2권4호
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• pp.208-216
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• 2002

Background: Reactive oxygen and nitrogen are produced by rheumatoid arthritis (RA) synovial tissue and can induce mutations in key genes. Normally, this process is prevented by a DNA mismatch repair (MMR) system that maintains sequence fidelity. Key members of the MMR system include MutS${\alpha}$ (comprised of hMSH2 and hMSH6), which can sense and repair single base mismatches and 8-oxoguanine, and MutS${\beta}$ (comprised of hMSH2 and hMSH3), which repairs longer insertion/deletion loops. Methods: To provide further evidence of DNA damage, we analyzed synovial tissues for microsatellite instability (MSI). MSI was examined by PCR on genomic DNA of paired synovial tissue and peripheral blood cells (PBC) of RA patients using specific primer sequences for 5 key microsatellites. Results: Surprisingly, abundant MSI was observed in RA synovium compared with osteoarthritis (OA) tissue. Western blot analysis of the same tissues for the expression of MMR proteins demonstrated decreased hMSH6 and increased hMSH3 in RA synovium. To evaluate potential mechanisms of MMR regulation in arthritis, fibroblast-like synoviocytes (FLS) were isolated from synovial tissues and incubated with the nitric oxide donor S-nitroso-N-acetylpenicillamine (SNAP). Western blot analysis demonstrated constitutive expression of hMSH2, 3 and 6 in RA and OA FLS. When FLS were cultured with SNAP, the RA synovial pattern of MMR expression was reproduced (high hMSH3, low hMSH6). Conclusion: Therefore, oxidative stress can relax the DNA MMR system in RA by suppressing hMSH6. Decreased hMSH6 can subsequently interfere with repair of single base mutations, which is the type observed in RA. We propose that oxidative stress not only creates DNA adducts that are potentially mutagenic, but also suppresses the mechanisms that limit the DNA damage.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제34권5호
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• pp.509-517
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• 2008

DNA 손상 치유 유전자 연구를 기초로 한 임상적 접근이 새로운 치료방법으로 떠오르고 있다. 많은 연구들이 중요한 DNA 수복유전자의 다형성을 찾아내어 각각의 단백질의 활동성에 대한 영향을 알아내고 특정한 치료법을 찾아내고 임상적 적용을 시도하고 결과를 평가하였다. 그 결과 암 치료에서 정상 세포와 암세포에서 DNA 수복 유전자의 발현 분석은 화학요법이나 방사선 치료에서 개인맞춤형 치료법을 가능하게 하고 있다. 예를 들어, NER이 결핍된 종양은 cisplatin 치료에 민감성을 나타내고, MMR 결핍세포는 알킬화 화학요법 약제에 높은 내성을 나타낸다. 선천성 비폴립성 결장암과 같은 MMR 결손종양 또한 알킬화 화학요법 약제에 의한 치료에 내성을 가진다. 신경교종(glioma)에서 MGMT 유전자 프로모터가 흔히 메틸화되는데 이것은 유전자 발현이 억제되고 알킬화 화학요법제에 대한 반응성을 증가시킨다. 향후 구강악안면외과 영역에서도 구강암의 발생의 위험성을 증가시킬 수 있는 더 많은 DNA 수복 유전자의 다형성을 발굴하고 임상적으로 개인맞춤형 치료법을 개발하고 적용할 수 있는 많은 연구가 필요할 것으로 사료된다.

• Toxicological Research
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• 제16권1호
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• pp.9-16
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• 2000

Ginseng (the root of Panax ginseng C. A. Meyer, Araliaceae) has been used for traditional medicine in China, Korea, Japan and other Asian countries. It is most often used as a general tonic, and it involves a wide range of pharmacological actions, such as antiaging, adaptogen-like effect to foreign deleterious infringement, immunoenhancement, antistress, antitumor, and antioxidant actions. Red ginseng showed anticarcinogenic activity against various chemical carcinogens in mouse and cancer-preventive effect of human being as on mice in experimental and epidemiological studies. In the present study, we have found the protective properties of red ginseng against vinyl carbamate (VC) which is the proximate carcinogen of ethyl carbamate and its ultimate carcinogenic epoxides. Red ginseng exhibited dose-dependent inhibition on the mutagenci activities of boty VC in the presence of S9 mix and vinyl carbamate epoxide (VCO) without metabolic activation in Salmonella typhimurium TA1535. Formation of DNA adducts from VCO was also attenuated in the presence of red ginseng. Oral administration of red ginseng prior to the topical application of each of the above carcinogens and TPA treatment resulted in significant reduction in both incidence and multiplicity of skin tumors in mice. These results indicate that red ginseng possesses a strong chemopreventive effect against mouse skin carcinogenesis induced by VC or VCO.