Shifting sensitivity of septoria tritici blotch compromises field performance and yield of main fungicides in Europe

Septoria tritici blotch (STB; Zymoseptoria tritici) is a severe leaf disease on wheat in Northern Europe. Fungicide resistance in the populations of Z. tritici is increasingly challenging future control options. Twenty-five field trials were carried out in nine countries across Europe from 2019 to 2021 to investigate the efficacy of specific DMI and SDHI fungicides against STB. During the test period, two single DMIs (prothioconazole and mefentrifluconazole) and four different SDHIs (fluxapyroxad, bixafen, benzovindiflupyr and fluopyram) along with different co-formulations of DMIs and SDHIs applied at flag leaf emergence were tested. Across all countries, significant differences in azole performances against STB were seen; prothioconazole was outperformed in all countries by mefentrifluconazole. The effects also varied substantially between the SDHIs, with fluxapyroxad providing the best efficacy overall, while the performance of fluopyram was inferior to other SDHIs. In Ireland and the UK, the efficacy of SDHIs was significantly lower compared with results from continental Europe. This reduction in performances from both DMIs and SDHIs was reflected in yield responses and also linked to decreased sensitivity of Z. tritici isolates measured as EC₅₀ values. A clear and significant gradient in EC₅₀ values was seen across Europe. The lower sensitivity to SDHIs in Ireland and the UK was coincident with the prevalence of SDH-C-alterations T79N, N86S, and sporadically of H152R. The isolates' sensitivity to SDHIs showed a clear cross-resistance between fluxapyroxad, bixafen, benzovindiflupyr and fluopyram, although the links with the latter were less apparent. Co-formulations of DMIs + SDHIs performed well in all trials conducted in 2021. Only minor differences were seen between fluxapyroxad + mefentrifluconazole and bixafen + fluopyram + prothioconazole; the combination of benzovindiflupyr + prothioconazole gave an inferior performance at some sites. Fenpicoxamid performed in line with the most effective co-formulations. This investigation shows a clear link between reduced field efficacy by solo SDHIs as a result of increasing problems with sensitivity shifting and the selection of several SDH-C mutations. The presented data stress the need to practice anti-resistance strategies to delay further erosion of fungicide efficacy.

Evidence for the association of target-site resistance in cyp51 with reduced DMI sensitivity in European Cercospora beticola field isolates

BACKGROUND

Cercospora leaf spot caused by Cercospora beticola is the most relevant foliar disease in sugar beet cultivation. In the last decade a decreasing sensitivity of C. beticola towards demethylation inhibitors (DMIs) occurred. Different mechanisms mediating a reduced sensitivity towards DMIs have been identified in different plant pathogens to date, such as target site mutations, over-expression or active excretion of the fungicide.

RESULTS

A sequencing of the cytochrome P450-dependent sterol 14α-demethylase gene sequence (cyp51) of diverse C. beticola isolates collected in different European countries with reduced DMI sensitivity was performed in order to find a possible correlation of mutations with higher EC₅₀ values. The amino acid alterations Y464S, L144F and I309T combined with L144F were found to be associated with a reduced sensitivity. Furthermore, mutations I387M, M145W and M145W with E460Q were found uniquely. Additionally, constitutive and fungicide triggered expression of cyp51 was assayed by means of RT-qPCR. A very strong induction of cyp51 mRNA expression in sensitive isolates suggests that the fungal cells upregulate expression to maintain ergosterol biosynthesis in DMI presence. The less intensive cyp51 induction in isolates with higher EC₅₀ values underlines the possible correlation of the found target-site mutations with reduced sensitivity.

CONCLUSION

This study provides new results about possible alterations in the target gene mediating reduced sensitivity of C. beticola towards DMIs and hypothesized a fungicide induced over-expression of the target enzyme CYP51 as natural reaction of the fungus to fungicide application. © 2020 Society of Chemical Industry.

Sensitivity of the Pyrenophora teres Population in Algeria to Quinone outside Inhibitors, Succinate Dehydrogenase Inhibitors and Demethylation Inhibitors

Net blotch of barley caused by Pyrenophora teres (Died.) Drechsler, is one of the most destructive diseases on barley in Algeria. It occurs in two forms: P. teres f. teres and P. teres f. maculata. A total of 212 isolates, obtained from 58 fields sampled in several barley growing areas, were assessed for fungicide sensitivity by target gene analysis. F129L and G137R mitochondrial cytochrome b substitution associated with quinone outside inhibitors (QoIs) resistance, and succinate dehydrogenase inhibitors (SDHIs) related mutations (B-H277, C-N75S, C-G79R, C-H134R, and C-S135R), were analyzed by pyrosequencing. In vitro sensitivity of 45 isolates, towards six fungicides belonging to three chemical groups (QoI, demethylase inhibitor, and SDHI) was tested by microtiter technique. Additionally, sensitivity towards three fungicides (azoxystrobin, fluxapyroxad, and epoxiconazole) was assessed in planta under glasshouse conditions. All tested isolates were QoI-sensitive and SDHI-sensitive, no mutation that confers resistance was identified. EC50 values showed that pyraclostrobin and azoxystrobin are the most efficient fungicides in vitro, whereas fluxapyroxad displayed the best disease inhibition in planta (81% inhibition at 1/9 of the full dose). The EC₅₀ values recorded for each form of net blotch showed no significant difference in efficiency of QoI treatments and propiconazole on each form. However, in the case of fluxapyroxad, epoxiconazole and tebuconazole treatments, analysis showed significant differences in their efficiency. To our knowledge, this study is the first investigation related to mutations associated to QoI and SDHI fungicide resistance in Algerian P. teres population, as well as it is the first evaluation of the sensitivity of P. teres population towards these six fungicides.

[Management of chronic pain using extended release tilidine : Quality of life and implication of comedication on tilidine metabolism]

BACKGROUND AND OBJECTIVES

The synthetic opioid tilidine is often used in chronic pain treatment. However, the activation via metabolism in patients with concomitant medication and reduced liver or kidney function is not thoroughly investigated. We therefore studied pain treatment efficacy, health-related quality of live and the metabolism of tilidine in patients with chronic pain.

METHODS AND MATERIALS

In all, 48 patients, who were on a stable dose of oral prolonged release tilidine for at least 7 days, were included in this observational multicenter study. Liver and kidney function were assessed in routine blood samples, concentrations of tilidine, nortilidine and bisnortilidine were determined using a validated LC/MS/MS method. Comedication was registered and patients experience with regard to quality of life, pain, gastrointestinal symptoms and adverse events was assessed in standardised questionnaires.

RESULTS

On average a daily dose of 180 mg tilidine was taken. Dose normalized plasma concentrations of the active metabolite nortilidine ranged between 1.6 ng/ml and 76.5 ng/ml (mean 29.2 ± 25.1 ng/ml). Ratios between tilidine and nortilidine were on average 0.28 (median = 0.13, standard deviation = 0.67). Patients were on 1 to 14 different concomitant medications. About 66% of the patients had sufficient pain treatment. Almost no opioid-induced constipation was observed. Only few patients had decreased kidney or liver function which did not result in elevated nortilidine concentrations.

CONCLUSION

Pain treatment using tilidine resulted in variable nortilidine concentrations which are obviously not strongly influenced by comedication or reduced liver or kidney function. Only a few side effects were observed with almost no opioid-induced constipation.

Competitive Fitness of Phakopsora pachyrhizi Isolates with Mutations in the CYP51 and CYTB Genes

Soybean rust (Phakopsora pachyrhizi) in Brazil is mainly controlled with applications of fungicides, including demethylation inhibitors (DMI) and quinone outside inhibitors (QoI). Isolates with less sensitivity to DMI and QoI have been reported, and these have been found to have mutations in the CYP51 and CYTB genes, respectively. There have been no reports of fitness costs in isolates with mutations in CYP51 and CYTB, and the aim of this work was to compare the competitive ability of isolates with lower DMI or QoI sensitivities with that of sensitive (wild-type) isolates. Urediniospores of sensitive wild-type isolates and isolates with different CYP51 or CYTB alleles were mixed and inoculated on detached soybean leaves. After 3 weeks, urediniospores were harvested and used as inoculum for the next disease cycle. Frequencies of relevant target site mutations were monitored using the pyrosequencing method over four disease cycles. Isolates with lower DMI sensitivity and different CYP51 alleles had competitive disadvantages compared with a DMI-sensitive, wild-type CYP51 isolate. In contrast, the isolate with the F129L mutation in the CYTB gene competed equally well with a QoI-sensitive, wild-type CYTB isolate under the conditions of this experiment. The CYP51 and CYTB alleles were stable in all isolates over four disease cycles when cultivated alone.

Emergence of succinate dehydrogenase inhibitor resistance of Pyrenophora teres in Europe

BACKGROUND

Net blotch caused by Pyrenophora teres is an important disease of barley worldwide. In addition to strobilurins (quinone ouside inhibitors) and azoles (demethylation inhibitors), succinate dehydrogenase inhibitors (SDHIs) are very effective fungicides for net blotch control. Recently, SDHI-resistant isolates have been found in the field. Intensive sensitivity monitoring programmes across Europe were carried out to investigate the situation concerning SDHI resistance in P. teres.

RESULTS

The first isolates with a lower sensitivity to SDHIs registered in barley were found in Germany in 2012 and carried the B-H277Y substitution in the succinate dehydrogenase enzyme. In 2013 and 2014, a significant increase in isolates with lower SDHI sensitivity was detected mainly in France and Germany, and the range of target-site mutations increased. Most of the resistant isolates carried the C-G79R substitution, which exhibits a strong impact on all SDHIs in microtitre tests. All SDHIs tested were shown to be cross-resistant. Other substitutions are gaining in importance, e.g. C-N75S in France and D-D145G in Germany. So far, no double mutants in SDH genes have been detected. Glasshouse tests showed that SDHI-resistant isolates were still controlled by the SDHI fluxapyroxad when applied preventively. To date, most isolates with C-G79R substitution have not simultaneously carried the F129L change in cytochrome b, which causes resistance towards QoI fungicides at low to moderate levels.

CONCLUSION

Several target-site mutations in the genes of subunits SDH-B, SDH-C and SDH-D with different impact on SDHI fungicides were detected. The pattern of mutations varied from year to year and between different regions. Strict resistance management strategies are recommended to maintain SDHIs as effective tools for net blotch control, especially in areas with low frequencies of resistant isolates. © 2016 Society of Chemical Industry.

Proposal for a unified nomenclature for target-site mutations associated with resistance to fungicides

Evolved resistance to fungicides is a major problem limiting our ability to control agricultural, medical and veterinary pathogens and is frequently associated with substitutions in the amino acid sequence of the target protein. The convention for describing amino acid substitutions is to cite the wild-type amino acid, the codon number and the new amino acid, using the one-letter amino acid code. It has frequently been observed that orthologous amino acid mutations have been selected in different species by fungicides from the same mode of action class, but the amino acids have different numbers. These differences in numbering arise from the different lengths of the proteins in each species. The purpose of the present paper is to propose a system for unifying the labelling of amino acids in fungicide target proteins. To do this we have produced alignments between fungicide target proteins of relevant species fitted to a well-studied 'archetype' species. Orthologous amino acids in all species are then assigned numerical 'labels' based on the position of the amino acid in the archetype protein. © 2016 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Differences in the efficacy of carboxylic acid amide fungicides against less sensitive strains of Plasmopara viticola

BACKGROUND

Plasmopara viticola is controlled by fungicides with different modes of action, including carboxylic acid amides (CAAs). The aim of this study was to evaluate differences in the response of CAA-resistant P. viticola strains towards CAAs.

RESULTS

The G1105S mutation affects all four CAAs, but with different impacts. While this confirms that they have the same mode of action, it shows that differences between CAAs can occur.

CONCLUSION

Further molecular modelling and docking studies are needed to gain a better understanding of the different behaviours reported here. © 2015 Society of Chemical Industry.

Detection of the F129L mutation in the cytochrome b gene in Phakopsora pachyrhizi

BACKGROUND

Asian soybean rust, caused by Phakopsora pachyrhizi, is mostly controlled by demethylation inhibitor (DMI) and quinone outside inhibitor (QoI) fungicides. Mutations in the cytochrome b (CYTB) gene can lead to pathogen resistance to QoIs. The occurrence of the mutations in codons 129, 137 and 143 in the CYTB gene was investigated, and a pyrosequencing assay was developed for rapid and quantitative detection of the F129L mutation.

RESULTS

Molecular analysis of the CYTB gene showed the presence of the F129L mutation in field samples and monouredinial isolates, while other mutations (G143A and G137R) were not found. The pyrosequencing was an effective method for quantitative detection of the F129L mutation, and many of the P. pachyrhizi samples showed high frequency of F129L.

CONCLUSION

This is the first report of the occurrence of the F129L mutation in P. pachyrhizi. The practical relevance of this mutation for field efficacy of QoIs needs further investigation. © 2015 Society of Chemical Industry.

Binding of the respiratory chain inhibitor ametoctradin to the mitochondrial bc1 complex

BACKGROUND

Ametoctradin is an agricultural fungicide that inhibits the mitochondrial bc1 complex of oomycetes. The bc1 complex has two quinone binding sites that can be addressed by inhibitors. Depending on their binding sites and binding modes, the inhibitors show different degrees of cross-resistance that need to be considered when designing spray programmes for agricultural fungicides. The binding site of ametoctradin was unknown.

RESULTS

Cross-resistance analyses, the reduction of isolated Pythium sp. bc1 complex in the presence of different inhibitors and molecular modelling studies were used to analyse the binding site and binding mode of ametoctradin. All three approaches provide data supporting the argument that ametoctradin binds to the Pythium bc1 complex similarly to stigmatellin.

CONCLUSION

The binding mode of ametoctradin differs from other agricultural fungicides such as cyazofamid and the strobilurins. This explains the lack of cross-resistance with strobilurins and related inhibitors, where resistance is mainly caused by G143A amino acid exchange. Accordingly, mixtures or alternating applications of these fungicides and ametoctradin can help to minimise the risk of the emergence of new resistant isolates.

A Botrytis cinerea Population from a Single Strawberry Field in Germany has a Complex Fungicide Resistance Pattern

Gray mold, caused by the fungus Botrytis cinerea, is one of the most important diseases of strawberry in Germany. The application of site-specific fungicides remains the main strategy to reduce disease incidence and severity in the field. Isolates (n = 199) were collected from fungicide-treated strawberry fruit at a German research site with a long history of fungicide efficacy trials against gray mold. Sensitivities to the six site-specific botryticides registered in Germany were determined using microtiter assays. Values for the concentration of a fungicide at which fungal development is inhibited by 50% (EC₅₀) ranged from 0.03 to ≥30 ppm for the succinate dehydrogenase inhibitor boscalid, 0.015 to ≥10 ppm for the hydroxyanilide fenhexamid, 0.009 to 0.739 ppm for the phenylpyrrole fludioxonil, 0.55 to 43.45 ppm for the dicarboximide iprodione, 0.021 to ≥3 ppm for the quinone outside inhibitor pyraclostrobin, and 0.106 to ≥30 ppm for the anilinopyrimidine pyrimethanil. Pyrosequencing revealed that amino acid substitutions in the target proteins Bos1 (I365S/N, V368F + Q369H), CytB (G143A), Erg27 (F412S), and SdhB (P225F, N230I, and H272R/Y) were associated with reduced sensitivity levels to the corresponding fungicide classes. In most cases, isolates with a decreased sensitivity to fludioxonil showed a reduced sensitivity to tolnaftate. This reduction is considered to be an indication of multidrug efflux pump activity. The amino acid change I365S, I365N, or V368F + Q369H in Bos1 and H272R in SdhB by itself showed EC₅₀ values of 3.99 to 14.73 ppm, 3.87 to 5.37 ppm, 4.81 to 15.63 ppm, and 2.071 to ≥30 ppm, respectively. When isolates that contained one of these mutations were also multidrug resistant, the ranges of EC₅₀ values shifted to 6.47 to 43.45 ppm for I365S, 7.28 to 29.84 ppm for I365N, 6.89 to 26.67 ppm for V368F + Q369H, and ≥30 ppm for H272R. The reported data suggest that the combination of multidrug resistance and an amino acid change in the target site may result in a lower sensitivity to the fungicides than one resistance mechanism by itself. Although 20% of the population analyzed was sensitive to all six different chemical classes, the majority showed reduced sensitivity to one (6%), two (13%), three (23%), four (17%), five (11%), and six (11%) different fungicides.

Sensitivity of Phakopsora pachyrhizi towards quinone-outside-inhibitors and demethylation-inhibitors, and corresponding resistance mechanisms

BACKGROUND

Since the invasion of Phakopsora pachyrhizi (Syd. & P. Syd.) in Brazil, there have been detrimental yield losses of soybeans [Glycine max (L.) Merr.]. Disease management is mainly based on fungicide treatment. The sensitivity of single P. pachyhrizi isolates towards different demethylation-inhibitors (DMIs) and quinone-outside-inhibitors (QoI) was surveyed and the corresponding resistance mechanisms were analysed.

RESULTS

The QoI-response remained stable, while a loss of sensitivity towards DMIs occurred. Molecular analyses of cytochrome b showed an intron after codon 143 which is reported to prevent the development of a G143A mutation. Analysis of cyp51 revealed that point mutations and overexpression are involved in the sensitivity reduction towards DMIs. Of the detected mutations, Y131F and Y131H, respectively, and K142R are likely homologous to mutations found in other pathogens. As suggested by modelling studies, these three mutations as well as additional mutations F120L, I145F and I475T correlate to increased effective doses of 50%, ED50 -values, towards all tested DMIs. Furthermore, a constitutive up-regulation of the cyp51-gene up to ten-fold was noticed in some of the DMI-adapted isolates, while all sensitive isolates responded as the wild type.

CONCLUSION

The G143A mutation is thought to result in significant as well as stable resistance factors towards QoIs, while other mutations play only a minor role. Since G143A development is prevented in Phakopsora pachyhrizi, a stable control of soybean rust with QoIs in future is rather likely. In contrast, a shifting in sensitivity towards DMIs has been observed, which is due to multiple independent mechanisms.

Detection of fos, jun and ras in newly-diagnosed childhood acute lymphoblastic-leukemia by immunocytochemistry and PCR

The expression of the oncogenes c-fos, c-jun and c-pan-ras was analyzed at the protein level in newly diagnosed cases of acute lymphoblastic leukemia (ALL) in children. Blast cells obtained from 104 children with untreated ALL were determined by the streptavidin-biotin-peroxidase method and specific antibodies. Of the ALL 52 cases were positive for Fos (50%), 65 for Jun (63%), and 22 for Ras (21%). Fos-positive ALL had a significantly higher relapse frequency (p=0.0002). A similar trend was found for Jun-positive ALL (p=0.073). In contrast, the expression of Ras showed no significant correlation with the relapse rate (p=0.98). Corresponding results were obtained for the relapse-free intervals. The relapse-free intervals were higher in patients with Fos- and Jun-positive leukemic cells than in patients with negative tumor cells (Fos: p<0.001; Jun: p=0.09; Ras: p=NS, log-rank test). In order to substantiate the significant correlation of c-fos-protein expression with the relapse rate the c-fos-mRNA expression was investigated in a collective of 20 patients by semi-quantitative PCR. The PCR-assay and immunocytochemistry corresponded in 14 of 20 cases (70%). The results of the PCR-assay demonstrated also a trend for increased c-fos-mRNA expression and higher relapse rate.

A Two-Step Molecular Detection Method for Pyrenophora tritici-repentis Isolates Insensitive to QoI Fungicides

Tan spot, caused by Pyrenophora tritici-repentis, is an important disease of wheat worldwide. To manage tan spot, quinone outside inhibitor (QoI) fungicides such as azoxystrobin and pyraclostrobin have been applied in many countries. QoI fungicides target the cytochrome b (cyt b) site in complex III of mitochondria and, thus, pose a serious risk for resistance development. The resistance mechanism to QoI fungicides is mainly due to point mutations in the cyt b gene. The objective of this study was to develop a molecular detection method for the four currently known mutations responsible for shifts in sensitivity toward QoI fungicides in P. tritici-repentis. Twelve specific primers were designed based on sequences from the National Center for Biotechnology Information accessions AAXI01000704 and DQ919068 and used to generate a fragment of the cyt b gene which possesses four known single-nucleotide polymorphisms (SNPs). These mutant clones served as positive controls because QoI-insensitive and -reduced-sensitive isolates of P. tritici-repentis have not yet been reported in the United States. The partial cyt b gene clones were sequenced to identify the SNPs at sites G143A and F129L. Genomic DNA of the mutated partial cyt b gene clones and the European QoI-insensitive and -reduced-sensitive isolates of P. tritici-repentis possessing G143A (GCT) and F129L (TTA, TTG, and CTC) mutations were amplified by polymerase chain reaction (PCR) using two specific primer pairs and were further digested with three specific restriction enzymes (BsaJI, Fnu4HI, and MnlI). The results of the digested PCR product from genomic DNA of known QoI-insensitive and -reduced-sensitive isolates of P. tritici-repentis had DNA bands consistent with the mutation GCT at G143A and the mutations TTA, TTG, and CTC at F129L. The amplified region at the F129 site also had 99% sequence similarity with P. teres, the net blotch pathogen of barley. To validate mutations, we further tested two isolates of P. teres known to have reduced sensitivity to QoI fungicides possessing the mutations TTA and CTC at F129L. After PCR amplification and restriction digestion, DNA bands identical to those observed for the partial cyt b mutant clones were detected. These results suggest that this newly developed two-step molecular detection method is rapid, robust, and specific to monitor QoI-insensitive and -reduce-dsensitive isolates of P. tritici-repentis.

Generation and characterization of isolates of Peronophythora litchii resistant to carboxylic acid amide fungicides

Four isolates of Peronophythora litchii with resistance to carboxylic acid amide (CAA) fungicides were selected on fungicide-amended agar. These isolates had various levels of resistance, as evidenced by their resistance factor (RF), which is the 50% effective concentration (EC(50)) value of a particular isolate divided by that of the wild-type parent. RF values to dimethomorph for the four isolates were 15, 24, 141, and >1,500. Resistance was stable for two isolates, while the EC(50) values decreased for the other two after repeated subculturing on fungicide-free medium. Cross-resistance occurred with all CAAs tested here (dimethomorph, mandipropamid, flumorph, and pyrimorph), but not with strobilurins (azoxystrobin and famoxadone) or other fungicides (metalaxyl, cymoxanil, and mancozeb). Studies on fitness parameters (mycelial growth, sporulation, spore germination, zoospore formation, aggressiveness, and temperature tolerance) in the parent wild-type and resistant isolates demonstrated that penalties in different parameters may be associated with CAA resistance, depending on the isolate. These studies show that Peronophythora litchii is able to express CAA resistance under laboratory conditions but it is not known if resistant strains could become established in the field and sensitivity monitoring studies are recommended.

Modulation of multidrug resistance in human ovarian cancer cell lines by inhibition of P-glycoprotein 170 and PKC isoenzymes with antisense oligonucleotides

Multidrug resistance in human ovarian carcinoma cell lines is caused by the expression of several related proteins, namely P-glycoprotein 170 (Pgp-170), glutathione S-transferase-pi GST-pi), and thymidylate synthase (TS). These proteins seem to be regulated by a common mechanism in which the expression of protein kinase C (PKC) is involved. Additionally, the function of Pgp-170 is dependent on PKC phosphorylation. However, in ovarian carcinoma cell lines the role of different PKC enzymes responsible for resistance is not quite clear. In the present study we circumvented resistance in taxol resistant human ovarian carcinoma cell lines with antisense oligonucleotides to PKC alpha and PKC beta mRNA and compared the effects with those obtained by Pgp-170 antisense oligonucleotides. We found a significant inhibition of cell number after treatment with Pgp-170 antisense oligonucleotides in combination with taxol. Additionally, resistance could be reversed by treatment with taxol and antisense oligomers to PKC alpha and PKC beta. This shows that regulatory correlations between these proteins exist and that inhibition of the mRNA of PKC alpha and PKC beta isoforms and Pgp-170 can reverse multidrug resistance.

Spontaneous apoptosis in ovarian cancer: an unfavorable prognostic factor

Apoptosis and cell proliferation play important roles in the cellular response to chemotherapy, and may have prognostic value. The percentage of apoptotic cells [apoptotic index (AI)] was evaluated in ovarian carcinomas of 25 patients by the terminal desoxynucleotidyl transferase-mediated dUTP-nick end labeling (TUNEL) technique. All patients were surgically treated and received postoperatively chemotherapy consisting of cytoxan and cisplatin or carboplatin. As a marker of proliferation the mRNA expression of histone H3 in tumor tissue was determined. In addition, tumor vascularity was assessed by immunohistochemistry and factor VIII. Patients with high AI had significantly shorter survival times (p=0. 0001) or recurrence-free intervals (p=0.004) than patients with low AI. No significant relationship was found between AI and histone H3 mRNA expression, however, an inverse correlation of AI with microvessel density was detected. Tumors with high AI had significantly lower microvessel count than tumors with low AI (p=0. 002). The obtained data suggest that AI can be predictive of treatment outcome in ovarian cancer.

Expression of the retinoblastoma tumor suppressor gene (RB-1) in acute leukemia

In this report we review current studies concerning the RB-1 gene expression in acute leukemias. The RB-1 gene was analyzed in several studies by protein-, RNA and DNA-techniques in acute lymphoblastic leukemia (ALL) as well as in acute myelogenous leukemia (AML). The frequency of RB-1 inactivation in ALL-patients ranged between 30% and 64% in several studies. Structural abnormalities of the RB-1 gene were reported in 18% of ALL-patients and in 27% of Philadelphia chromosome-positive ALL, respectively. The proportion of AML-patients with absent RB-1 protein expression ranged between 19% and 55%. Structural RB-1-abnormalities in AML were predominantly reported in leukemias with monocytic differentiation. Furthermore, the prognostic value of an abnormal RB-1 gene expression was also estimated in some studies. In childhood ALL RB-1 inactivation was reported to have prognostic significance while in contrast, in another study on adults no prognostic value of RB-1 was found. In 4 out of 5 documented studies AML-patients with RB-1 inactivation generally had a poorer prognosis. In conclusion, RB-1 inactivation is frequently observed in acute leukemia. The prognostic value of low RB-1 expression is controversial but the majority of published studies found low RB-1 expression to be a negative prognostic predictor, in acute leukemia.

Prognostic implications of cyclins (D1, E, A), cyclin-dependent kinases (CDK2, CDK4) and tumor-suppressor genes (pRB, p16INK4A) in childhood acute lymphoblastic leukemia

Immunohistochemistry was used to analyze samples of 40 newly diagnosed childhood acute lymphoblastic leukemias (ALL) for their expression of cyclins (D1, E, A), cyclin-dependent kinases (cdk2, cdk4) and tumor-suppressor genes (pRb, p16INK4A), in order to discover whether or not the expression of these various proteins may be of prognostic relevance for the survival of children with ALL. Patients with ALL who were strongly positive for cyclin D1 had a lower probability of remaining in first continuous remission than ALL patients who were negative or weakly positive for this trait. There was also a significant correlation between expression of cyclin D1 and frequency of recurrence. For cyclin E and cyclin A, in contrast, there was no difference in the duration of relapse-free-intervals or the frequency of recurrence in patients. Children with cdk4-positive ALL had a lower probability of remaining in first continuous remission than children with cdk4-negative ALL. No prognostic relevance was found for cdk2. Patients with ALL who expressed pRb had a higher probability and patients who expressed p16 a lower probability of remaining in first continuous remission, but the results were not statistically significant. This investigation demonstrated that cyclin D1 and cdk4 were the most important prognostic factors for children with ALL, and that the combination of them showed the strongest prognostic relevance.

Expression of lung resistance-related protein (LRP) in initial and relapsed childhood acute lymphoblastic leukemia

Thirty-eight children with initial and 25 children with relapsed lymphoblastic leukemia (ALL) were analyzed for the expression of LRP (lung resistance protein or p110 major vault protein) using immunocytochemistry. LRP expression was found in 18 of 38 (47%) children with initial ALL and in 17 of 25 (68%) children with relapsed ALL. Children with initial ALL and without LRP expression had significantly longer relapse-free intervals than patients with LRP expression.

Deoxycytidine kinase mRNA expression in childhood acute lymphoblastic leukemia

Initial and relapsed childhood acute lymphoblastic leukemias (ALL) were investigated for mutations and expression of deoxycytidine kinase (dCK). dCK mediating toxicity of 1-beta-D-arabinofuranosylcytosine was analyzed semiquantitatively by RT-PCR and by single-strand conformation polymorphism. We found that patients with initial ALL experienced more frequently a relapse if dCK expression was low or absent. No mutations were found in initial and relapsed ALL.

Prognostic value of basic fibroblast growth factor and its receptor (FGFR-1) in patients with non-small cell lung carcinomas

Tumour specimens of 206 patients with untreated non-small cell lung carcinomas (NSCLC) were analysed immunohistochemically for the expression of the basic fibroblast growth factor (bFGF) and for its receptor (FGFR-1, Flg). Seventy of the tumours showed weak expression, 109 moderate and 27 high expression of bFGF. Thirty-eight tumours had low expression of FGFR-1, 116 had moderate and 52 cases high expression. Patients with high FGFR-1 expression had significantly shorter survival times than patients with weak or moderate expressions (P < 0.05), but there was no significant correlation between bFGF expression and patient survival. The results of the multivariate analysis demonstrated that FGFR-1 in the presence of stage is not an independent prognostic factor.

Green tea catechins (EGCG and EGC) have modulating effects on the activity of doxorubicin in drug-resistant cell lines

The chemopreventive effect of polyphenols from green tea [e.g. (-)-epigallocatechin gallate (EGCG) and (-)-epigallocatechin (EGC)] against cancer has been demonstrated in several studies. The aim of this investigation was to prove whether these compounds modulate the activity of antineoplastic drugs. Therefore, the influence of EGCG and EGC was tested on doxorubicin-resistant murine sarcoma (S180-dox) and human colon carcinoma (SW620-dox) cell lines. Both substances showed a sensitizing effect on the cell lines if they had been treated with doxorubicin. These results suggest that protein kinase C may be inhibited by EGCG and EGC, and this may lead to a reduced expression of some drug resistance related proteins.

Messenger RNA expression of resistance proteins and related factors in human ovarian carcinoma cell lines resistant to doxorubicin, taxol and cisplatin

Doxorubicin- (OAW-dox, SK-OV-dox), taxol- (OAW-tax, SK-OV-tax) and cisplatin- (SK-OV-cis) resistant cells derived from the parental OAW-42 and SK-OV-3 cell lines were established. OAW-42 sublines showed high resistance, the SK-OV-3 sublines only low resistance. OAW-42 sublines showed a cross-resistance profile typical of multidrug resistance (MDR). The sublines of SK-OV-3 showed a cross-resistance profile different from the OAW-42 sublines. The mRNA expression of several resistance proteins and related factors was analyzed. An overexpression of P-glycoprotein 170 (P-170), glutathione-S-transferase-pi (GST-pi), thymidylate synthase (TS), glutathione peroxidase (GP) and c-jun was found in OAW-dox and OAW-tax cells. Additionally, OAW-tax cells expressed a higher mRNA level of protein kinase Cbeta2. DNA analysis revealed a 2-fold gene amplification of P-170, whereas the genes for GST-pi, TS and GP were not amplified. SK-OV-dox and SK-OV-tax cells showed a decreased level of histone 3 (H3) and TS mRNA. This shows that the sublines of OAW-42 developed resistance by co-expression of several resistance-related proteins and proto-oncogenes whereas the sublines of SK-OV-3 expressed resistance by decreased expression of the proliferation-dependent proteins H3 and TS.

Cyclin A is associated with an unfavourable outcome in patients with non-small-cell lung carcinomas

Specimens of formalin-fixed, paraffin-embedded non-small-cell lung carcinomas (NSCLCs; n = 187) were analysed immunohistochemically for expression of cyclin A. The analysis was intended to determine whether cyclin A has additional prognostic value for predicting patients' survival and drug response. Of the 187 NSCLCs, 141 cases (75%) showed expression of cyclin A. Patients with cyclin A-positive carcinomas had significantly shorter median survival times than patients with cyclin A-negative carcinomas (79 vs 129 weeks, P = 0.045). Similar results were obtained with more homogeneous groups of patients: patients with only T3 tumours, patients with epidermoid carcinomas and patients with lymph node involvement. The clinical parameters (age, stage, histology, extent of tumour size, lymph node involvement) had no influence on expression of cyclin A. A direct correlation between cyclin A and the proportion of S-phase cells (P = 0.08) and an inverse relationship between cyclin A and the proportion of G0/G1-phase cells (P = 0.04) were found. Furthermore, a significant correlation between the expression of cyclin A and the response of NSCLC to doxorubicin in vitro was detected (P = 0.026).

Apoptotic index, Fas and bcl-2 in initial and relapsed childhood acute lymphoblastic leukaemia

Seventy-two samples with initial and 23 samples with relapsed childhood acute lymphoblastic leukaemia (ALL) were investigated for apoptotic index (AI) and for Fas expression. AI was determined by DNA-fragmentation using deoxynucleotidyl terminal transferase and Fas expression by immunocytochemistry. bcl-2 mRNA expression was measured in 50 initial and 20 relapsed ALL. The patients were discriminated in groups with low and high AI, Fas-protein expression and bcl-2mRNA expression by the mean value. AI was higher in relapsed than in initial ALL. The mean survival was significantly higher in patients with low AI (p= 0.034). This was also true for the relapse-free interval, however, this result was borderline significant (p= 0.064). AI was directly correlated with expression of Fas and inversely correlated with bcl-2 mRNA expression. These results suggest that Fas and - with limitations - bcl-2 may influence the apoptotic process in childhood ALL and that enhanced apoptotic activity predicts poor prognosis.

Angiogenic growth factors and their receptors in non-small cell lung carcinomas and their relationships to drug response in vitro

Tumor specimens of non-small cell lung carcinomas (NSCLC) from previously untreated patients (n = 153) were analysed immunohistochemically for expression of vascular endothelial growth factor (VEGF), VEGF-receptor (Flt-1), basic fibroblast growth factor (bFGF) and FGF-receptor (FGFR-1, (Flg). Expression of the proteins was compared with the in vitro response of the tumors against doxorubicin. The data clearly demonstrate that a significant relationship exists between VEGF (p < 0.001) and Flt-1 expression (p < 0.01) and drug response. The expression of VEGF and Flt-1 was lower in resistant than in sensitive tumors. In contrast, no significant interrelationship was found between expression of bFGF and response to doxorubicin. However, there exists a significant correlation between the expression of FGF-receptor (FGFR-1) and the response of the carcinomas to doxorubicin (p < 0.05). Expression of FGFR-1 was more frequently negative or weak in resistant and more frequently moderate or high in sensitive NSCLC. The data from this investigation clearly demonstrate that a significant interrelationship exists between the expression of VEGF, VEGF-receptor Flt-1 and FGF-receptor, FGFR-1 and the response of NSCLC to doxorubicin in vitro.

Association of vascular endothelial growth factor expression with tumor cell proliferation in ovarian carcinoma

Vascular endothelial growth factor (VEGF) is a potent angiogenic factor that may also function as an autocrine growth regulator. Thirty-one ovarian carcinomas were investigated for mRNA expression of VEGF and of a proliferation-dependent gene (histone H3) using slot-blot analysis. Tumor vascularity was assessed by immunohistochemistry and factor VIII. All tumors were demonstrated to express VEGF and histone H3, though to various degrees. There was a good correlation between VEGF mRNA values and histone H3 mRNA values (r = 0.71, p < 0.05). No correlation was found between tumor cell proliferation and tumor vascularity. There was no significant difference in relapse-free interval or overall survival between tumors with low and high VEGF expression. The close correlation of VEGF expression with tumor cell proliferation in this study raises the possibility of autocrine stimulation of ovarian carcinoma.

Expression of resistance-related proteins in tumoral and peritumoral tissues of patients with lung cancer

Twenty tumoral and peritumoral tissues from patients with lung cancer were analyzed immunohistochemically for the drug resistance-related proteins P-glycoprotein (P-170), topoisomerase II (Topo-II), glutathione S-transferase-pi (GST-pi), metallothionein (MT), heat shock protein-70 (HSP-70) and the putative regulators of resistance (ErbB1, Fos and Jun). Protein expression of Topo-II, GST-pi, MT, HSP-70, ErbB1, Fos and Jun was elevated in tumor tissue in comparison to normal tissue. The different expression of the proteins between tumoral and normal tissues was statistically significant for Topo-II (P = 0.05), MT (P = 0.03), and HSP-70 (P = 0.01), whereas ErbB1 showed a borderline significance. The expression of the proteins was frequently increased in smokers in comparison to non-smokers. In general, the increase of the proteins of smokers corresponded in tumoral and non-tumoral tissue. Different expression was only found with MT and HSP-70 which were higher in tissues of smokers.

Coexpression of cyclin D1 and retinoblastoma gene product (pRb) in human squamous cell lung carcinomas is associated with increased tumor take rate in nude mice

Samples from 72 squamous cell lung carcinomas were analyzed immunohistochemically for the expression of cyclin D1 and pRb. Expression of cyclin D1 was found in 61% and expression of pRb in 39% of the cases. The take rate of human squamous cell lung carcinomas in nude mice was significantly different according to the expression of cyclin D1 and expression of pRb in primary human tumors [cyclin D1-negative (32%) vs. cyclin D1-positive (59%); P=0.026; pRb-negative (34%) vs. pRb-positive (71%); P=0.002]. The take rate was improved by coexpression of both proteins [both proteins negative/both proteins positive: 12% vs. 80% (P=0.00005)]. An association of the take rate and clinical parameters (age, extent of tumors, lymph node involvement, stage) could not be observed. Coexpression of cyclin D1 and pRb is also a prognostic factor for the patients' survival.

Expression and prognostic value of the retinoblastoma tumour suppressor gene (RB-1) in childhood acute lymphoblastic leukaemia

In a retrospective analysis, acute lymphoblastic leukaemia (ALL) blast cells of 102 children were investigated for the expression of the retinoblastoma susceptibility (RB)-1 gene at mRNA level by dot blot hybridization and semiquantitative RT-PCR. 56 patients were analysed by dot blot hybridization and 35 representative patients out of this group by semiquantitative RT-PCR. Two additional groups of patients (23 patients with initial and 23 patients with relapsed ALL) were also investigated by semiquantitative RT-PCR. RB-1 gene expression was detectable in all investigated ALL at different levels. According to the relative mRNA expression the patients were discriminated by the median value in groups with low or high RB-1 expression. The Kaplan-Meier estimates showed that patients with low RB-1 expression had a lower probability of remaining in first remission (P = 0.03) and a significantly higher risk to succumb to their disease (P = 0.03). Furthermore, the comparison of the results between initial and relapsed ALL showed that the relapses had significantly lower RB-1 mRNA expression (P = 0.02). The overall survival of the patients was shorter in both groups when RB-1 gene expression was low. A multivariate analysis, including age, sex, immunological subtype, initial white blood cell count and RB-1 expression, identified RB-1 as an independent prognostic predictor (P = 0.017) in addition to the initial white blood cell count (P = 0.00001). In conclusion, low RB-1 expression is an unfavourable prognostic predictor in initial and relapsed childhood ALL. The RB-1 gene expression in relapsed ALL is significantly lower than in initial ALL.

Microvessel density, expression of proto-oncogenes, resistance-related proteins and incidence of metastases in primary ovarian carcinomas

Relationships between the incidence of metastatic spread and microvessel density, expression of proto-oncogene products, or expression of resistance-related proteins were investigated in human ovarian carcinomas by immunohistochemistry. Ovarian carcinomas with a high microvessel density showed a significantly increased formation of metastases (P = 0.005). Tumors with positive immunoreactivity of c-jun and c-myc products had a higher metastatic spread; however, these results were not statistically significant. A marginally significant correlation existed between the expression of erbB1 (EGFR) and metastatic spread (P = 0.05). No significant relationship was found between the expression of the resistance-related proteins P-glycoprotein or glutathione S-transferase-pi and the incidence of metastases. Furthermore, no correlation was detected between expression of the heat shock protein 70 and the occurrence of metastases.

Retinoblastoma (Rb) protein expression and resistance in squamous cell lung carcinomas

The purpose of this study was to prove the value of Rb protein expression as a prognostic factor for patients with squamous cell lung carcinoma. The expression of Rb in 75 carcinomas was analyzed immunohistochemically and the resistance to doxorubicin was investigated in vitro. Rb-negative carcinomas were more frequently resistant than Rb-positive carcinomas (p<0.05). A trend for a correlation between the expression of Rb and the expression of glutathione S-transferase-pi was detectable (p=0.08). Patients with Rb-positive carcinomas had a trend for better prognosis, but this result was not statistically significant.

Expression of heat shock proteins, glutathione peroxidase and catalase in childhood acute lymphoblastic leukemia and nephroblastoma

In this study we analyzed the mRNA expression of the heat shock proteins 27 and 70, and the expression of the radical scavenging enzymes catalase and glutathione peroxidase (GPX) in childhood acute lymphoblastic leukemia (ALL, n = 54) and in nephroblastoma (n = 34). We found a significant positive correlation between both heat shock proteins and also between glutathione peroxidase and both heat shock proteins in ALL and nephroblastoma. There was also a significant correlation between catalase and glutathione peroxidase detectable. Furthermore, we investigated whether the expression of the heat shock proteins and the antioxidant enzymes glutathione peroxidase and catalase have implications in the clinical outcome in ALL. However, we found no significant correlation between the expression of these proteins and relapse rate, the relapse free intervals or the overall survival.

Messenger RNA expression of resistance factors in human tumor cell lines after single exposure to radiation

Resistance of tumor cells to chemotherapeutic drugs can not only be caused by treatment with antineoplastic agents but also by radiotherapy. The aim of this study was to analyze whether ionizing radiation can influence the mRNA expression of proteins which have been found to be involved in drug resistance of tumor cells. Human tumor cell lines (MCF-7, LXF and Sk-Mel) were treated with single doses of irradiation (5, 10 and 20 Gy). The expression of the resistance related proteins glutathione S-transferase-pi (GST-pi), topoisomerase II alpha (Topo II), thymidylate synthase (TS), O6-methylguanine-DNA-methyltransferase (MGMT), P-glycoprotein (Pgp), glutathione peroxidase (GPX) multidrug resistance-associated protein (MRP) and also of the heat-shock protein 70 (HSP 70) were determined at the mRNA level during the time interval from 1.5 to 72 h post-irradiation and compared with their corresponding controls. We also examined whether a relationship exists between these proteins and the proliferative activity (histone 3, Ki-67, statin) of the cells. We found that exposure of MCF-7, LXF and Sk-Mel cells to ionizing radiation increases the expression of the mRNA of GST-pi. Topo II, TS, HSP 70 and proliferation markers were also altered by exposure to ionizing radiation, but there was no common response of the three cell lines. No significant changes were observed in the expression of MGMT, Pgp, GPX and MRP after radiation treatment. Drug resistance tests revealed that irradiated MCF 7 cells were less sensitive to doxorubicin than non-irradiated control cells. Our results indicate that ionizing irradiation modifies the expression of some proteins involved in drug resistance and the response of MCF 7 cells to doxorubicin and may, therefore, play a role in clinical drug response.

Up-regulation of heat shock protein 70 in adenocarcinomas of the lung in smokers

Tumour samples of smokers (n = 32) and non-smokers (n = 21) with previously untreated adenocarcinomas of the lung were analysed, immunohistochemically, for expression of the heat shock protein 70 (hsp70). A correlation between smoking habits and expression of hsp70 was found. Of the tumours from the 21 non-smokers 12 (57%) and of the 32 smokers 24 tumours (75%) showed high hsp70 expression. The expression of hsp70 depended on the number of cigarettes smoked daily. Of the patients who smoked more than 20 cigarettes, 16 out of 18 had tumours with a high hsp70 expression (89%; p = 0.028).

Expression of resistance-related proteins in nephroblastoma after chemotherapy

Tumor tissues of untreated and cytostatic-agent-treated patients with nephroblastomas were investigated for expression of resistance-related proteins (P-glycoprotein, glutathione S-transferase-pi, glutathione peroxidase and topoisomerase II) to ascertain whether resistance proteins are changed after treatment. Tumor tissue was analyzed by means of mRNA. Twenty-three children were treated with actinomycin D and vincristine for 4 to 8 weeks. Eight children received no preoperative chemotherapy. In untreated patients, no expression of P-glycoprotein was seen, whereas, in the patients who were treated with actinomycin D and vincristine, 12 out of 23 tumors showed increased P-glycoprotein expression (> mean value). Although we found no difference between treated and untreated tumors for glutathione S-transferase-pi, we found significant differences in the expression of glutathione peroxidase. In the 8 untreated patients, 7 tumors showed low glutathione peroxidase (< mean value) and one high (> mean value) glutathione-peroxidase-mRNA content. With treatment, 11 tumors expressed low levels and 12 tumors high levels of mRNA. A significant positive correlation between P-glycoprotein and glutathione peroxidase was found. In addition, of the 8 untreated patients, 2 had low topoisomerase-II expression, and 6 high expression. With treatment, the expression was reduced in 18 tumors, and only 5 tumors had high levels of this protein. These results were confirmed by PCR and immunohistochemistry.

Effects of single doses of irradiation on the expression of resistance-related proteins in murine NIH 3T3 and human lung carcinoma cells

In this report the effects of single doses of ionizing radiation on the mRNA expression of several proteins involved in multiple drug resistance were analyzed. Murine NIH 3T3 cells treated with single doses of 5, 10 and 20 Gy during the time interval from 1.5 to 72 h after irradiation were compared with their corresponding controls at the same points of time. The glutathione S-transferase-pi (GST pi) level was elevated in cells treated with 10 or 20 Gy from 24 to 72 h after irradiation compared with the control. Topoisomerase II alpha and thymidylate synthase were decreased in irradiated cells 24-72 h after exposure. These down-regulations were associated with cellular proliferation, determined by mRNA expression of the proliferation marker histone 3. Irradiated cells exhibited no alteration in the P-glycoprotein or glutathione peroxidase mRNA content. The finding that GST pi mRNA was overexpressed after irradiation was validated by investigations on a human lung carcinoma cell line (LXF 289) on the mRNA and protein level. Thus, our results indicate that irradiation alters the expression of proteins involved in multidrug resistance and may, therefore, play a role in clinical drug response.

Heat shock (hsp70) and resistance proteins in non-small cell lung carcinomas

The aim of the study was to prove whether or not an association exists between the heat shock protein 70 (hsp70) and drug resistance. Tumor samples of 90 patients with previously untreated non-small lung carcinomas were investigated immunohistochemically for expression of resistance related proteins. Additionally, resistance to doxorubicin was determined using a short term test. No association between resistance related proteins. Additionally, resistance to doxorubicin was determined using a short term test. No association between resistance to doxorubicin and hsp70 was found. Of 63 resistant tumors, 33 showed low and 30 high hsp70 expression. Of the 26 sensitive tumors, 11 had low and 16 had high hsp70 expression. No relationship could be found between P-glycoprotein which is related to multidrug resistance and hsp70 expression or between hsp70 expression and expression of topoisomerase II, thymidylate synthase and metallothionein. On the other hand, a trend was noted for tumors with high glutathione S-transferase-pi expression to show high hsp70 expression. In addition, there was a significant relationship between hsp70 and catalase positivity. These data indicate that heat shock and stress promote intracellular oxidative damage and catalase is necessary for protection.

Induction of resistance-proteins and oncoproteins in murine and human tumor-cell lines after irradiation

The aim of this investigation was to analyze whether or not ionizing radiation can induce the expression of resistance- and oncoproteins in murine sarcoma 180 cells and several human carcinoma cell lines. For assessment of the proteins the streptavidin-biotin peroxidase-complex method was performed using specific antibodies. Expression of glutathione S-transferase-pi and thymidylate-synthase was increased after a single dose of irradiation which was accompanied by a lower sensitivity against cisplatin and 5-fluorouracil. No differences in protein expression could be detected for P-glycoprotein 170 and topoisomerase II. Differences in the expression of the oncoproteins c-Fos and c-ErbB1 were also found after irradiation. In contrast, a decreased expression of topoisomerase II was found after fractionated irradiation. This was confirmed by mRNA analysis.

Altered messenger-RNA expression of glutathione-dependent enzymes after single and repeated exposure to ethanol

1The effect of ethanol (0.2-2.5%) on glutathione S-transferase-pi and glutathione peroxidase mRNA expression was studied in NIH 3T3 mouse fibroblasts after single and fractionated exposure to ethanol. After single exposure to 1.5% ethanol an elevation of about 1.6 fold of glutathione S-transferase-pi mRNA level was found, while a reduction of about two fold of glutathione peroxidase mRNA expression in treated cells was measured compared to control cells. Similar effects were found in cells after fractionated ethanol administration. Therefore, repeated exposure to ethanol (1.5%, 2.5%) showed no stronger alterations in the mRNA expression of both glutathione dependent enzymes.

Messenger RNA expression of resistance factors and their correlation to the proliferative activity in childhood acute lymphoblastic leukemia

In this report we analyzed the mRNA expression of the resistance-related enzymes DNA topoisomerase II (Topo II), thymidylate synthase (TS), glutathione S-transferase-pi (GST-pi) and glutathione peroxidase (GP) in childhood acute lymphoblastic leukemia (ALL) and their correlation to the proliferative activity, determined by Ki-67. RNA of blast cells from 54 children with untreated ALL were examined by dot blot hybridization. We found a significant positive correlation between Topo II and TS and cell proliferation. No significant correlation was detected between the mRNA expression of the glutathione-dependent enzymes GST-pi or GP and Ki-67. The results were substantiated by a semiquantitative RT-PCR-assay and by immunocytochemistry.

Determination of DNA topoisomerase II in newly diagnosed childhood acute lymphoblastic leukemia by immunocytochemistry and RT-PCR

The expression of DNA-topoisomerase II was analysed at the protein level in newly diagnosed cases of acute lymphoblastic leukemia (ALL) in children. Blast cells obtained from 81 children with untreated ALL were determined by means of immunocytochemistry. Of the ALL, 49 (60%) were positive for topoisomerase II and 32 (40%) negative. No significant correlation was found between the expression of topoisomerase II and the relapse rate or relapse-free intervals. These results were substantiated by determining the topoisomerase II mRNA expression in a collective of 21 patients by semiquantitative PCR. The PCR-assay and immunocytochemistry corresponded in 13 of 21 cases (62%).