Chaperonin containing T-complex polypeptide subunit eta is a potential marker of joint contracture: an experimental study in the rat

Joint contracture is a fibroproliferative disorder that restricts joint mobility, resulting in tissue degeneration and deformity. However, the etiology of joint contracture is still unknown. Chaperonin containing T-complex polypeptide subunit eta (CCT-eta) is reported to increase in fibrotic diseases. The purpose of this study was to investigate whether CCT-eta is implicated in joint contracture and to determine the role of CCT-eta in the progression of joint contracture by analyzing a rat model. We immobilized the left knee joint of rat by internal fixation for 8 weeks. The non-immobilized right leg served as a control. The range of motion (ROM) of the knee was investigated. Fibroblasts were obtained from the posterior joint capsule of the joints. The outcome was followed by quantitative real-time polymerase chain reaction (qRT-PCR), Western blot, fibroblast migration assay, and collagen assay. The effect of CCT-eta on the functions of fibroblasts was observed by utilizing a short inhibitory RNA (siRNA) targeting CCT-eta. The ROM of the immobilized joints was significantly limited compared to the contralateral joints (p < 0.05). Fibroblasts derived from the contractive joints showed higher mRNA and protein expressions of CCT-eta in parallel with alpha-smooth muscle actin (α-SMA) compared to the cells from the contralateral knees (p < 0.05). siRNA-mediated downregulation of CCT-eta inhibited the expressions of both CCT-eta and α-SMA. Moreover, the reduction of CCT-eta also significantly decreased fibroblast functions such as cell mobility and collagen synthesis (all p < 0.05). Our findings indicate that CCT-eta appears to be a potential marker of joint contracture disease.

Electronic supplementary material

The online version of this article (doi:10.1007/s12192-015-0624-x) contains supplementary material, which is available to authorized users.     

Synthesis of Mitomycin C and Decarbamoylmitomycin C N2 deoxyguanosine-adducts

Mitomycin C (MC) and Decarbamoylmitomycin C (DMC) – a derivative of MC lacking the carbamate on C10 – are DNA alkylating agents. Their cytotoxicity is attributed to their ability to generate DNA monoadducts as well as intrastrand and interstrand cross-links (ICLs). The major monoadducts generated by MC and DMC in tumor cells have opposite stereochemistry at carbon one of the guanine–mitosene bond: trans (or alpha) for MC and cis (or beta) for DMC. We hypothesize that local disruptions of DNA structure from trans or cis adducts are responsible for the different biochemical responses produced by MC and DMC. Access to DNA substrates bearing cis and trans MC/DMC lesions is essential to verify this hypothesis. Synthetic oligonucleotides bearing trans lesions can be obtained by bio-mimetic methods. However, this approach does not yield cis adducts. This report presents the first chemical synthesis of a cis mitosene DNA adduct. We also examined the stereopreference exhibited by the two drugs at the mononucleotide level by analyzing the formation of cis and trans adducts in the reaction of deoxyguanosine with MC or DMC using a variety of activation conditions. In addition, we performed Density Functional Theory calculations to evaluate the energies of these reactions. Direct alkylation under autocatalytic or bifunctional conditions yielded preferentially alpha adducts with both MC and DMC. DFT calculations showed that under bifunctional activation, the thermodynamically favored adducts are alpha, trans, for MC and beta, cis, for DMC. This suggests that the duplex DNA structure may stabilize/oriente the activated pro-drugs so that, with DMC, formation of the thermodynamically favored beta products are possible in a cellular environment.     

丝裂霉素促进活性氧自由基生成的研究

本文探讨了抗癌药丝裂霉素对活性氧自由基,超氧负离子自由基(O_2~-),羟自由基(OH)生成反应的作用,实验表明,丝裂霉素对O_2~-及OH的生成有明显的促进作用,其作用随着丝裂霉素浓度的增加而加强。分别测定了它对两种自由基生成反应的促进率。     

Synthesis of Mitomycin C and decarbamoylmitomycin C N6 deoxyadenosine-adducts

Mitomycin C (MC), an anti-cancer drug, and its analog, decarbamoylmitomycin C (DMC), are DNA-alkylating agents. MC is currently used in the clinics and its cytotoxicity is mainly due to its ability to form Interstrand Crosslinks (ICLs) which impede DNA replication and, thereby, block cancer cells proliferation. However, both MC and DMC are also able to generate monoadducts with DNA. In particular, we recently discovered that DMC, like MC, can form deoxyadenosine (dA) monoadducts with DNA. The biological role played by these monoadducts is worthy of investigation. To probe the role of these adducts and to detect them in enzymatic digests of DNA extracted from culture cells treated by both drugs, we need access to reference compounds i.e. MC and DMC dA-mononucleoside adducts. Previous biomimetic methods used to generate MC and DMC mononucleoside adducts are cumbersome and very low yielding. Here, we describe the diastereospecific chemical synthesis of both C-1 epimers of MC and DMC deoxyadenosine adducts. The key step of the synthesis involves an aromatic substitution reaction between a 6-fluoropurine 2′-deoxyribonucleoside and appropriately protected stereoisomeric triaminomitosenes to form protected-MC-dA adducts with either an S or R stereochemical configuration at the adenine-mitosene linkage. Fluoride-based deprotection methods generated the final four reference compounds: the two stereoisomeric MC-dA adducts and the two stereoisomeric DMC-dA adducts. The MC and DMC-dA adducts synthesized here will serve as standards for the detection and identification of such adducts formed in the DNA of culture cells treated with both drugs.     

Mitomycin C potentiates TRAIL-induced apoptosis through p53-independent upregulation of death receptors

The discovery of the molecular targets of chemotherapeutic medicines and their chemical footprints can validate and improve the use of such medicines. In the present report, we investigated the effect of mitomycin C (MMC), a classical chemotherapeutic agent on cancer cell apoptosis induced by TRAIL. We found that MMC not only potentiated TRAIL-induced apoptosis in HCT116 (p53?/?) colon cancer cells but also sensitized TRAIL-resistant colon cancer cells HT-29 to the cytokine both in vitro and in vivo. MMC also augmented the pro-apoptotic effects of two TRAIL receptor agonist antibodies, mapatumumab and lexatumumab. At a mechanistic level, MMC downregulated cell survival proteins, including Bcl2, Mcl-1 and Bcl-XL, and upregulated pro-apoptotic proteins including Bax, Bim and the cell surface expression of TRAIL death receptors DR4 and DR5. Gene silencing of DR5 by short hairpin RNA reduced the apoptosis induced by combination treatment of MMC and TRAIL. Induction of DR4 and DR5 was independent of p53, Bax and Bim but was dependent on c-Jun N terminal kinase (JNK) as JNK pharmacological inhibition and siRNA abolished the induction of the TRAIL receptors by MMC.     

小梁切除术中应用丝裂霉素C 对角膜内皮细胞的影响

目的:观察小梁切除术中应用丝裂霉素C(MMC)对角膜内皮细胞的影响。方法:收集2010年9月2011年5月在我院行小梁切除术的青光眼患者60例(78眼),随机分为术中应用丝裂霉素C的36例(46眼)患者为A组,术中不用丝裂霉素C的24例(32眼)为B组,分别观察术前、术后1个月和术后3个月两组眼压(IOP)、角膜内皮细胞的密度(CD)、平均细胞面积(AVG)及细胞面积变异系数(CV),分析其数量的改变及两组间的差异。结果:A组术前眼压为(35.4±13.7)mmHg,B组术前眼压为(32.5±13.5)mmHg差异无统计学意义(P>0.05),A组术后1个月及术后3个月眼压分别为(15.7±3.7)mmHg、(17.0±3.2)mmHg,均低于B组的(19.4±3.7)mmHg、(20.2±2.1)mmHg,差异有统计学意义(P<0.05)。A组术前、术后1个月及术后3个月角膜内皮细胞密度分别为(2475±484)个/mm2、(2199±373)个/mm2、(2164±332)个/mm2;平均细胞面积分别为(431.4±67.6)μm2、(480.6±66.8)μm2、(463.8±46.2)μm2;细胞面积变异系数分别为(31.1±7.4)%、(34.4±6.3)%、(31.2±7.5)%;术后1个月及术后3个月各参数与术前比较,差异均有统计学意义(P<0.05)。B组术前、术后1个月及术后3个月角膜内皮细胞密度分别为(2342±94)个/mm2、(2185±215)个/mm2、(2074±218)个/mm2;平均细胞面积分别为(453.9±94.8)μm2、(516.3±100.8)μm2、(499.81±106.4)μm2;细胞面积变异系数分别为(30.2±3.0)%、(32.7±2.9)%、(31.4±4.3)%;除术后3个月角膜内皮细胞与术前比较有意义(P<0.05)外,余参数术后1个月及术后3个月与术前比较差异均无统计学意义(P>0.05)。术后1个月A组的角膜内皮细胞丢失率为10.4%高于B组的6.1%,差异有统计学意义(P<0.05);术后3个月A组的角膜内皮细胞丢失率为11.1%高于B组的10.0%,差异无统计学意义(P>0.05)。结论:小梁切除术中用丝裂霉素C的降压效果比不用丝裂霉素C的效果好,但短期内前者角膜内皮细胞的丢失率高于后者。     

丝裂霉素C对Erwinia herbicola表达及运转冰核活性蛋白方式的影响

利用添加丝裂霉素C(MMC)于不同培养基中,并在不同培养条件下对草生欧文氏菌10025A(E．herbicola 10025A)诱导培养,首次证实该菌表达冰核活性蛋白的活性及运转分泌冰核活性蛋白方式是不同。研究结果显示,MMC的加入可以提高细菌培养物的冰核活性,该现象可以解释为MMC对E．herbicola的作用能够激活细胞SOS应急系统的反应,诱导细胞合成部分参与修复DNA损伤的酶和蛋白因子,达到对E．herbicola诱导表达冰核蛋白通过高尔基体形成小液泡,向膜外分泌的方式,同时对E．herbicola细胞分裂后的形态也发生明显的影响。这对研究细胞在恶劣环境的生存机制以及获取该条件下的蛋白具有重要的意义,对低温生物的研究也将产生积极地影响。     

小梁切除术中应用丝裂霉素C对角膜内皮细胞的影响

目的：观察小梁切除术中应用丝裂霉素C（MMC）对角膜内皮细胞的影响。方法：收集2010年9月2011年5月在我院行小梁切除术的青光眼患者60例（78眼）,随机分为术中应用丝裂霉素c的36例（46眼）患者为A组,术中不用丝裂霉素c的24例（32眼）为B组。分别观察术前、术后1个月和术后3个月两组眼压（10P）、角膜内皮细胞的密度（co）、平均细胞面积（AVG）及细胞面积变异系数（cv）,分析其数量的改变及两组间的差异。结果：A组术前眼压为（35．4±13．7）mmHg,B组术前眼压为（32．5±13．5）mmHg差异无统计学意义（P〉0．05）,A组术后1个月及术后3个月眼压分别为（15．7±3．7）mmHg、（17．0±3．2）mmHg,均低于B组的（19．4±3．7）mmHg、（20．2±2．1）mmHg,差异有统计学意义（P〈0．05）。A组术前、术后1个月及术后3个月角膜内皮细胞密度分别为（2475±484）个／mm2、（2199±373）个／mm2、（2164±332）个／mm2;平均细胞面积分别为（431．4±67．6）μm2、（480．6±66．8）μm2、（463．8±46．2）μm2;细胞面积变异系数分别为（31．1±7．4）％、（34．4±6．3）％、（31．2±7．5）％;术后1个月及术后3个月各参数与术前比较,差异均有统计学意义（P〈0．05）。B组术前、术后1个月及术后3个月角膜内皮细胞密度分别为（2342±94）个／mm2、（2185＋215）个／mm2、（2074218）个／mm2;平均细胞面积分别为（453．9土94．8）μm2、（516.3±100．8）μm2、（499．81＋106．4）μm2;细胞面积变异系数分别为（30．2土3．0）％、（32．7±2．9）％、（31．4±4．3）％;除术后3个月角膜内皮细胞与术前比较有意义（P〈0．05）外,余参数术后1个月及术后3个月与术前比较差异均无统计学意义（P〉0．05）。术后1个月A组的角膜内皮细胞丢失率为10．4％高于B组的6．1％,差异有统计学意义（P〈0．05）;术后3个月A组的角膜内皮细胞丢失率为11．1％高于B组的10．0％,差异无统计学意义（P〉0．05）。结论：小梁切除术中用丝裂霉素C的降压效果比不用丝裂霉素C的效果好,但短期内前者角膜内皮细胞的丢失率高于后者。     

Sensitive and convenient high-performance liquid chromatographic method for the determination of mitomycin C in human plasma

An improved high-performance liquid chromatographic assay for the cytostatic drug mitomycin C in plasma is presented. The principal steps are precipitation of plasma proteins with acetonitrile, lyophilization of the supernatant and reversed-phase chromatography on a Hypersil ODS 5 μm column with 0.01 M NaH₂PO₄ buffer (pH 6.5)-methanol (70:30, v/v) in isocratic mode. At a flow-rate of 1.3 ml/min a column pressure of 180–220 bar resulted. Porfiromycin served as internal standard. UV detection was performed at 365 nm. Quantitation limit based on a coefficient of variation <10% in intra- and inter-day assay was 5 μg/l mitomycin C, detection limit based on a signal-to-noise ratio of 3 was 1 μg/l. Recovery was 100% and linearity was shown for the whole range of concentration (1–500 μg/l). None of the five drugs used during chemoembolisation interfered with the assay in vitro. The assay meets the requirements for pharmacokinetic studies of mitomycin C in patients as regards sensitivity and ease of use.     

Mitomycin C induces genomic rearrangements involving transposable elements in Drosophila melanogaster

Summary Mitomycin C was injected into the abdomen of male flies of the y ² sc¹ w^aG strain of Drosophila melanogaster. They were mated with females bearing attached-X chromosomes, and the male offspring (F₁) were analysed for the appearance of mutations in the X chromosome. We observed y ¹ and sc ⁺ reversions induced either by excision of mdg4 (gypsy) with retention of one long terminal repeat (LTR) or by insertion of a foreign sequence into mdg4, partial reversion of the w ^aG mutation, w ^aGw ^aGd, and unstable f mutations. The overall mutation frequency was considerably higher than in control flies of the y ² sc¹ w^aG strain. Possible mechanisms of genomic rearrangements induced by Mitomycin C, in particular the role of homologous recombination, are discussed.     

Hypothermia Prevents the Ischemia-Induced Translocation and Inhibition of Protein Kinase C in the Rat Striatum

The effect of hypothermia on the ischemia-induced changes in the subcellular distribution of protein kinase C (PKC) (gamma), -(beta II), and -(alpha) and the activity of PKC was studied in striatal homogenates of rats subjected to 20 min of cerebral ischemia. The effect of postischemic cooling was also studied. During normothermic ischemia, PKC(gamma) and -(beta II) increased 3.9- and 2.9-fold, respectively, in the particulate fraction, signifying a translocation of PKC to cell membranes. The levels of PKC(alpha) did not change significantly. PKC activity decreased during ischemia by 52% and 47% (p less than 0.05) in the particulate and cytosolic fractions, respectively, and remained inhibited for the 1 h recovery period. In hypothermic animals, there was no evidence of translocation, and the inhibition of PKC activity was completely abolished. Hypothermia induced in the recovery phase, however, did not affect PKC distribution or activity. The protective effect of intraischemic hypothermia may in part be due to the prevention of the ischemia-induced translocation and subsequent downregulation of PKC, possibly through a temperature-dependent modification of the cell membranes.     

Mitomycin C potentiates TRAIL-induced apoptosis through p53-independent upregulation of death receptors: Evidence for the role of c-Jun N-terminal kinase activation

The discovery of the molecular targets of chemotherapeutic medicines and their chemical footprints can validate and improve the use of such medicines. In the present report, we investigated the effect of mitomycin C (MMC), a classical chemotherapeutic agent on cancer cell apoptosis induced by TRAIL. We found that MMC not only potentiated TRAIL-induced apoptosis in HCT116 (p53−/−) colon cancer cells but also sensitized TRAIL-resistant colon cancer cells HT-29 to the cytokine both in vitro and in vivo. MMC also augmented the pro-apoptotic effects of two TRAIL receptor agonist antibodies, mapatumumab and lexatumumab. At a mechanistic level, MMC downregulated cell survival proteins, including Bcl2, Mcl-1 and Bcl-XL, and upregulated pro-apoptotic proteins including Bax, Bim and the cell surface expression of TRAIL death receptors DR4 and DR5. Gene silencing of DR5 by short hairpin RNA reduced the apoptosis induced by combination treatment of MMC and TRAIL. Induction of DR4 and DR5 was independent of p53, Bax and Bim but was dependent on c-Jun N terminal kinase (JNK) as JNK pharmacological inhibition and siRNA abolished the induction of the TRAIL receptors by MMC.     

Quantitation of mitomycin C in human ocular tissues by high-performance liquid chromatography–photo-diode array detection

A chromatographic method, which can quantitate mitomycin C (MMC) along with two antiglaucoma drugs, is described. The separation of MMC, alphagan and timolol was performed on a reversed-phase C₁₈ column with water–methanol–trifluoroacetic acid (65:35:0.01, v/v) as the mobile phase. By monitoring at 360, 248 and 296 nm, the lower limits of detection for MMC, alphagan and timolol are, respectively, 1.0, 2.0 and 5.0 ng (injection amount) at three-time S/N ratio. The dynamic ranges of quantitation for the three drugs are, respectively, 1.0 ng–10.0 μg, 2.0 ng–10.0 μg and 5.0 ng–10.0 μg with linearity being larger than 0.9960. This method was applied to the determination of MMC levels in Tenon’s and trabeculum tissues of 10 glaucoma patients. MMC levels in these tissues, which were obtained from glaucoma filtering surgery, were determined following a multiple extraction with methanol. The recovery of MMC for a two-batch extraction was better than 91.2%. The reproducibility of measurement for the MMC levels in these tissues is 2.5–6.0% RSD for triplicate injections. The intra-day variation of retention times for the MMC peaks was less than 1.6% RSD (n=3). The inter-day variation of retention times for the MMC peaks was less than 4.8% RSD (n=3). MMC was detectable in three trabeculum tissues out of 10 cases (ranging from 0.8 to 25.5 ng/mg specimen), while MMC was detected in nine Tenon’s tissues out of 10 cases (ranging from 0.3 to 21.1 ng/mg specimen). The results obtained show that the method is sensitive and selective for the quantitation of MMC.     

Mitomycin C, 4-nitroquinoline-1-oxide and ethyl methanesulfonate induced long-lived lesions in DNA which result in SCEs during successive cell cycles in human lymphocytes

The present study was carried out in order to analyze how persistent the lesions in DNA are which elicit sister-chromatid exchanges (SCEs), induced by three different chemical agents, mitomycin C (MMC), 4-nitroquinoline-1-oxide (4NQO) and ethyl methanesulfonate (EMS), in proliferating human lymphocytes. Cells were exposed to the mutagens for 1 h just before starting bromodeoxyuridine substitution and SCEs were examined in third-cycle metaphases showing three-way-differential staining, by means of our previously standardized method. The results show that, in spite of the fact that these three compounds have different modes of action, the lesions induced by all of them seem to be capable of persisting in DNA and eliciting SCEs for at least three successive cell cycles.     

A Comparative Study of the Preventive Effects of Mitomycin C and Chitosan on Intraarticular Adhesion after Knee Surgery in Rabbits

We sought to compare the preventive effects of mitomycin-C(MMC) and chitosan on intraarticular adhesion after knee surgery in rabbits. For this purpose, 48 New-Zealand rabbits were randomly and equally divided into MMC, chitosan, and control groups. Approximately 10 × 10 mm(2) of the cortical bone was removed from both sides of left femoral condyle and the cancellous bone underneath was exposed. The decorticated areas were topically treated with MMC and chitosan while control group was treated with physiological saline. The lower left limb was fixed in flexed position with Kirschner-wire for 4 weeks postoperatively. After 4 weeks, gross and histopathological examination, biochemical analysis, and fibroblast counts were performed on knee intraarticular adhesion in each group. The data show mild membrane-like fibrous intraarticular adhesion, presented in loose, in MMC group. There was moderate intraarticular adhesion in chitosan group while in controls; there was large-size compact fibrous tissue adhesion. Hydroxyproline contents and fibroblast quantity of MMC and chitosan groups were lower (P < 0.05) than that of control group. We, therefore, concluded that MMC and chitosan could prevent intraarticular adhesion of the knee in rabbits by inhibiting fibroblast proliferation and reducing collagenous fiber formation while MMC had a better preventive effect than that of chitosan.     

Stability of C3 Convertase in the Rat Classical Complement Pathway

It has been reported that rat serum complement causes efficient hemolysis of antibody-sensitized sheep erythrocytes (EA) at 20 C but not at 37 C. In connection with this, we demonstrated that C3 convertase of rat complement was significantly unstable at 37 C using purified components of rat complement.     

Differentiation of Fanconi anemia and aplastic anemia using mitomycin C test in Tunisia

Fanconi anemia (FA) is a recessive chromosomal instability syndrome that is clinically characterized by multiple symptoms. Chromosome breakage hypersensitivity to alkylating agents is the gold standard test for FA diagnosis. In this study, we provide a detailed laboratory protocol for accurate assessment of FA diagnosis based on mitomycin C (MMC) test. Induced chromosomal breakage study was successful in 171 out of 205 aplastic anemia (AA) patients. According to the sensitivity of MMC at 50 ng/ml, 38 patients (22.22%) were diagnosed as affected and 132 patients (77.17%) as unaffected. Somatic mosaicism was suspected in an 11-year-old patient with a FA phenotype. Twenty-six siblings of FA patients were also evaluated and five of them (19.23%) were diagnosed as FA. From this study, a standard protocol for diagnosis of FA was developed. It is routinely used as a diagnostic test of FA in Tunisia.