Catechol‐O‐methyltransferase,a new target for pancreatic cancer therapy

Catechol‐O‐methyltransferase (COMT) is an important molecule in different types of cancers. Its biological effect and therapeutic significance, however, rarely been investigated fully in pancreatic cancer. Immunohistologically, high COMT expression was significantly correlated with the longer overall survival of patients (P < 0.05), indicating its protective nature. The effects of COMT on cell growth, apoptosis, and invasion were evaluated using overexpression and silencing methods. In detail, we carried out experiments using one stably transduced and two transiently transfected pancreatic cancer cell lines in vitro, and one stably transduced cell line in vivo mice xenograft models. In vitro experiments showed that COMT inhibited cell proliferation, enhanced gemcitabine‐induced apoptosis, and inhibited cell invasion in stably transduced and transiently transfected cell lines by regulating the PI3K/Akt pathway, p53, and E‐cadherin. The COMT overexpressed and silenced cell lines showed significantly inhibited and enhanced growth capacities in in vivo xenograft models, respectively. In conclusion, COMT suppressed pancreatic cancer and its high expression predicted longer survival time. The interaction of COMT with the PI3K/Akt pathway makes it a potential target for therapy.     

Schizophrenia-like neurophysiological abnormalities in 22q11.2 deletion syndrome and their association to COMT and PRODH genotypes

22q11.2 deletion syndrome (22q11.2DS) is a common genetic risk factor for the development of schizophrenia. We investigated two neurophysiological endophenotypes of schizophrenia – P50 sensory gating and mismatch negativity in 22q11.2DS subject and evaluated their association with catechol O-methyltransferase (COMT) and proline dehydrogenase (PRODH) genetic variants. We also assessed the association of neurophysiological measures with schizophrenia-like symptomatology in 22q11.2DS. Fifty-nine subjects, 41 with 22q11.2DS and 18 typically developing controls, participated in the study. The participants with 22q11.2DS were genotyped for the COMT Val¹⁵⁸Met (rs4680) and PRODH Gln¹⁹Pro (rs2008720) and Arg¹⁸⁵Trp (rs4819756) polymorphisms. Following psychiatric evaluation, all the participants underwent neurophysiological recordings and executive function assessment. The 22q11.2DS group showed poorer sensory gating of the P50 response than the controls. Within the 22q11.2DS group, the COMT Met allele was associated with poorer sensory gating, while both the COMT Met allele and the PRODH Pro-Arg haplotype were associated with smaller mismatch negativity amplitudes. Smaller mismatch negativity amplitudes predicted greater impairment of executive functions and greater severity of schizophrenia-like negative symptoms in 22q11.2DS. The current study demonstrates that sensory gating impairments that are typical of schizophrenia are found in 22q11.2DS subjects. Our results further suggest that COMT and PRODH genetic variations contribute to sensory gating and mismatch negativity schizophrenia-like impairments in 22q11.2DS, possibly via dopaminergic/glutamatergic networks. The associations of mismatch negativity impairments with increased severity of schizophrenia-like negative symptoms and poorer executive functions performance in our 22q11.2DS sample suggest that mismatch negativity is a potential endophenotype for schizophrenia in 22q11.2DS.     

No association of SIDS with two polymorphisms in genes relevant for the noradrenergic system: COMT and DBH

Aim: Recent research suggests that genetic variance determining the strength of noradrenergic transmitting might contribute to the aetiology of SIDS. We have typed 2 functional polymorphisms of relevance for both biosynthesis and catabolism of noradrenalin: The Val158Met single-nucleotide polymorphism (SNP) of the Catechol-O-methyl transferase gene (COMT) and the 1021C/T SNP of the dopamine dehydroxylase gene (DBH). Methods: COMT and DBH were typed in 171 and 196 SIDS cases and 213 and 244 controls, respectively, using PCR followed by digestion with restriction enzymes. Typing was performed using a QIAxcel automatic electrophoresis unit. Results: Both SNPs were in Hardy-Weinberg equilibrium, and for none of these polymorphisms, an association with SIDS could be demonstrated. The allelic frequencies of the DBH locus were C: 78.32% and T: 21.68% in SIDS and C: 77.66% and T: 22.34% in controls. For the COMT locus, the allelic frequencies were A: 51.17% and G: 48.83% in SIDS and A: 52.82% and G: 47.18% in controls. Conclusion: Despite these negative results, the noradrenergic system is still an attractive candidate as modulator of SIDS risk to our eyes. There are several genes involved in this system that have not been studied up to now.     

Electrosynthesis of novel π-extended benzofuran derivatives of porphyrincatecholes

Two new functionalized π-extended benzofuran catechol porphyrins and nanostructured Mn-porphyrins have been synthesized by a green one-pot method and structurally characterized by spectroscopic analysis. The electro-oxidation of 5,10,15,20-tetrakis(2,3-dihydroxyphenyl) porphyrins(1a-b) with four catechol units in the presence of 3-hydroxy-1H-phenalene-1-one (3) as bidentate nucleophile has been done and benzofuran rings have formed by the intermolecular and intramolecular Michel addition reactions. Coulometry and voltammetry results allowed us to propose four independent ECEC mechanisms for the electrochemical oxidation pathway. Functionalization of the porphyrins affected their photophysical properties such as the efficiency of the fluorescence that would support the energy transfer between the porphyrin core and the substituted subunits.     

Carbonyl side-chain of catechol compounds is a key structure for the suppression of copper-associated oxidative DNA damage in vitro

Catechol is possibly carcinogenic to humans (International Agency for Research on Cancer, IARC). The key mechanism could include its oxidative DNA-damaging effect in combination with reductive–oxidative metals like Cu. We found that DNA damage was suppressed by introducing an α-carbonyl group to catechol at C4-position to produce carbonyl catechols. During the oxidative DNA-damaging process, catechols but not carbonyl catechols were oxidized to o-quinone; however, coexisting Cu(II) was reduced to Cu(I). Carbonyl catechols were possibly arrested at the oxidation step of semiquinones in the presence of Cu(II). Cu(I)-binding to DNA was stronger than Cu(II)-binding, on the basis of the circular dichroism spectral change. None of the carbonyl catechols induced such change, suggesting sequestration of Cu(I) from DNA. Solid-phase extraction experiments and spectrophotometric analyses showed the formation of semiquinone chelates with Cu(I). Thus, chelate formation could explain the suppression mechanism of the Cu–catechol-dependent DNA damage by terminating the reduction–oxidation cycle. Structural modifications such as introducing an α-carbonyl group to catechol at C4-position would contribute to reducing the risk and improving industrial and medical potentials of aromatic/phenolic compounds sustaining our daily lives.     

新疆伊犁地区食管鳞癌与儿茶酚-O-甲基转移酶基因Val158Met多态性的关联分析

目的 探讨儿茶酚-O-甲基转移酶(COMT)基因缬氨酸(Val)158甲硫氨酸(Met)(G→A转换)多态性在新疆伊犁地区人群中的分布及与食管鳞癌(ESCC)的关系.方法 采用以医院为基础的病例对照研究方法,研究对象共622名,包括214例ESCC患者,408名年龄、性别、民族相匹配的正常对照.以聚合酶链反应-限制性片段长度多态性方法分析COMT基因G/A多态性.结果 622名受试者COMT基因型频率分布依次为GG型占47.3%,GA型占42.3%,AA型占10.4%;等位基因G为68.4%,A为31.6%.食管癌组与正常对照组COMT基因型及等位基因频率分布差异无统计学意义(P＞0.05).分层分析显示,年龄≤60岁的食管癌组与正常对照组之间COMT基因型(x2=6.101)和等位基因频率(x2=4.493)差异有统计学意义(P值均＜0.05);哈萨克族、维吾尔族、汉族ESCC组间等位基因频率比较差异有统计学意义(x2=6.671,P＜0.05);三个民族正常对照组间COMT基因型(x2=13.567)及等位基因频率(x2=11.321)分布比较差异均有统计学意义(P值均＜0.05).将年龄及性别校正后,新疆伊犁地区食管癌组与正常对照组COMTVal158Met多态性在哈萨克族、维吾尔族、汉族之间差异均无统计学意义.结论 COMT基因Val158Met单核苷酸多态可能不是新疆伊犁地区食管鳞癌危险性的遗传标志.

Abstract：

Objective To explore the relationship between polymorphism of catechol-O-methyltransferase (COMT) gene valine (Val) 158 methionine (Met) (G to A transition)and the distribution in population and esophageal squamous cell carcinoma (ESCC) in Yili prefecture of Xinjiang.Methods A hospital based case-control study was adopted, a total of 622 subjects, which including 214 ESCC patients and 408 age, gender and ethnicity-matched normal control individuals.The polymorphism of COMT gene G to A transition was analyzed with PCR-restriction fragment length polymorphism approaches.Results The COMT genotype frequencies in 622 subjects in Yili prefecture were GG genotype accounted for 47.3%, GA type for 42.3% and AA type for 10.4%, G allele was 68.4% and A allele was 31.6%.There was no statistical difference in the COMT genotype and frequencies of allele distribution between ESCC group and control group.Furthermore, stratified analysis indicated that there was statistical difference between ESCC group and control group in subjects less than 60 years old.There was statistical difference in the allele distribution among Kazak,Uygur and Han ESCC groups.The COMT genotype and frequency of allele distribution among normal control groups of the three ethnic groups were statistically different.After corrected age and gender,there was no statistical difference in COMT Val158Met polymorphisms among Kazakh, Uygur and Han ethnic groups in both ESCC and control groups in Yili Prefecture of Xinjiang.Conclusion COMT gene Val158Met single nucleotide polymorphism may not be the genetic markers of ESCC risk in Yili Prefecture of Xinjiang.     

儿茶酚胺氧位甲基转移酶基因在结直肠癌组织中的表达

目的 研究儿茶酚胺氧位甲基转移酶(COMT)基因及其编码蛋白在结直肠癌组织和正常结直肠黏膜中的表达情况.方法 留取2009年1月至8月诊治的22例结直肠癌患者的肿瘤组织和正常结直肠黏膜组织,提取标本的总RNA和总蛋白,采用RT-PCR及Western blot方法在基因水平和蛋白水平检测COMT在结直肠癌肿瘤和正常黏膜组织中的表达情况,并应用组织芯片检测COMT蛋白在结直肠癌组织中的表达情况,通过灰度测定比较肿瘤组织与正常组织之间目的基因和蛋白表达水平的差异.结果 在mRNA水平上.结果 肠癌肿瘤组织中COMT基因表达水平的平均光密度值为53 514±15 513,显著高于正常结直肠黏膜组织的4529±1698(P<0.05).Westem blot结果显示可溶性COMT蛋白(S-COMT)在结直肠癌肿瘤组织中表达水平的平均光密度值为54 967±11 919,显著高于正常结直肠黏膜组织的平均光密度值25 962±6713(P<0.05),而膜结合型COMT蛋白(MBCOMT)在两者的表达情况差异无统计学意义.组织芯片检测结果显示COMT蛋白主要定位于细胞质,肿瘤组织中的表达水平在染色强度和阳性率方面显著高于正常结直肠黏膜组织(P<0.05).结论 COMT基因及其编码蛋白在结直肠癌组织中的表达水平显著高于其在正常结直肠黏膜中的表达水平,提示该基因可能在结直肠肿瘤的发生、发展中发挥一定作用.     

儿茶酚-○-甲基转移酶基因多态性与精神分裂症发病特点的关系

目的:在中国汉族人群中寻找儿茶酚-O-甲基转移酶(catecholamine-O-methyl transferase, COMT)基因Val158Met多态性与精神分裂症发病特点之间的关系. 方法:使用病例-对照研究方法,对符合诊断标准的476名精神分裂症患者/207名正常对照就COMT基因Val158Met多态性进行检测并进行关联分析.结果: (1)非慢性患者的Val158Val基因型Val158等位基因分布频率显著高于对照组,对年龄、性别等调整后结果仍然成立; (2) 早发病组(25岁前起病)患者杂合子(Val158Met)及等位基因Met158分布频率显著高于晚发病组(P<0.05).结论:COMT基因可能与精神分裂症或某些临床特点存在关联.     

Synthesis and characterization of a catechol-terminated alkanethiolate monolayer adsorbed on gold

Structural, redox, and metal ion binding characterizations of the monolayer formed by the chemisorption of 3,4-dihydroxyphenethyl mercaptan (DHPM) on gold are described. This system was explored as a model for investigations of surface-immobilized molecules that contain redox-transformable coordination sites for binding metal ions from solution. The characterizations were carried out using infrared reflection spectroscopy, X-ray photoelectron spectroscopy, cyclic voltammetry, and long optical pathlength thin-layer spectroscopy. The XPS data show that this monolayer adsorbs as a thiolate, and the IRS results indicate that the average orientation of the aromatic ring plane is close to the surface normal. Cyclic voltammetry reveals that the pendant catechol/quinone undergoes the expected two-electron, two-proton redox transformation; however, the oxidized form of the couple is unstable, particularly in alkaline aqueous solutions. A determination of Cu(II) binding ability to the surface-immobilized catechol moieties, using a long optical pathlength thin-layer cell to follow the depletion of Cu(II) from solution, indicated that the complexation of the metal was not substantially different from that for the solution form of catechol. The instability of the oxidized form of the ligand, nevertheless, precluded an assessment of its metal ion binding ability. An approach using these data for estimating the conditional formation constant for the surface complexation reaction is also developed.