Martin Filipits

A Saccharomyces cerevisiae upstream activating sequence mediates induction of peroxisome proliferation by fatty acids

Peroxisome proliferation in Saccharomyces cerevisiae is induced by fatty acids via as yet unknown mechanisms. We have initiated a study of these mechanisms by identifying control sequences sufficient for fatty acid control of the CTA1 gene (encoding the peroxisomal catalase A). Promoter regions previously shown to be necessary for control were tested for their potential to mediate induction by oleic acid to a CYC1::lacZ fusion gene. A region previously demonstrated to control CTA1 via the ADR1 transcription activator (bp -156 to -184) does not mediate induction by oleic acid. In contrast, an adjacent sequence (-184 to -198) is sufficient for oleic acid induction, and a neighbouring element (-197 to -215) has marginal inducing activity. These two elements are characterized by a consensus sequence, 5-CGGNNNTNA (peroxisome box), which is found in a number of S. cerevisiae peroxisomal protein-encoding genes. Mutation of either the CGG or the TNA block in the box has a dramatic down-regulating effect on the gene expression in oleic acid medium.

Expression of MRP1, LRP and Pgp in breast carcinoma patients treated with preoperative chemotherapy

Our purpose was to determine the expression of the drug resistance factors multidrug resistance protein (MRP1), lung resistance protein (LRP) and P-glycoprotein (Pgp) in breast carcinoma patients treated with preoperative chemotherapy. We have studied the expression of these proteins in breast carcinomas by immunohistochemistry both prior (n = 80) and after (n = 68) preoperative chemotherapy and compared their expression with response to preoperative chemotherapy. In paired samples prior and after chemotherapy expression of drug resistance factors was significantly lower in prechemotherapy samples as compared with postchemotherapy specimens. This was observed for MRP1 (62% vs. 88%, P < 0.001), LRP (65% vs. 97%, P < 0.001) and Pgp (55% vs. 100%, P < 0.001). Prechemotherapy expression of MRP1 was more frequently observed in patients with distant metastases than in those without (50% vs. 8%, P = 0.02). No associations were observed between LRP expression and clinical parameters. Pgp expression was more frequently detected in lobular carcinomas than in ductal carcinomas (93% vs. 46%, P = 0.001) and in patients with positive lymph nodes than in patients with negative lymph nodes (65% vs. 31%, P = 0.008) but was independent of other clinical parameters. No significant associations were found between the prechemotherapy or postchemotherapy expression of either of these three proteins and response to preoperative chemotherapy. However, prechemotherapy MRP1 expression was significantly associated with shorter progression-free survival of the patients (P = 0.02), whereas no such associations were observed for either LRP or Pgp. In conclusion, preoperative chemotherapy increases the expression of MRP1, LRP and Pgp. Response to chemotherapy is not associated with pre- or postchemotherapy expression levels of these drug resistance proteins but time to progression may be influenced by prechemotherapy MRP1 expression.

Drug resistance factors in acute myeloid leukemia: a comparative analysis

To compare the clinical relevance of drug resistance factors in de novo acute myeloid leukemia (AML), we determined their relationship to both response to induction chemotherapy and survival of the patients in univariate as well as multivariate analyses. The drug resistance factors immunocytochemically studied in 111 patients at the time of diagnosis included the lung resistance protein (LRP), P-glycoprotein (P-gp), multidrug resistance protein (MRP1) and bcl-2. In the univariate analyses, age (P = 0.005), karyotype (P = 0.03), LRP (P = 0.003), P-gp (P = 0.02) and bcl-2 (P = 0.03) predicted for response to induction chemotherapy, whereas MRP1 had no predictive value. Age (P = 0.05), karyotype (P = 0.05) and LRP (P = 0.03) retained their predictive value in the multivariate logistic regression analyses. With regard to overall survival, age (P = 0.008), karyotype (P = 0.006), LRP (P = 0.001) and P-gp (P = 0.01) were of prognostic value in the univariate Cox regression analyses but only age (P = 0.01), karyotype (P = 0.02) and LRP (P = 0.01) retained their prognostic significance in the multivariate analyses. A risk score based on the number of independent prognostic factors allowed division of patients into four groups with different outcome. In these groups, the complete remission rates were 93%, 75%, 47% and 33%, respectively, and median overall survival was 2.4, 1.2, 0.6 and 0.2 years, respectively. Thus, several drug resistance factors did predict outcome in the univariate analyses but LRP was the only drug resistance factor with independent predictive and prognostic significance. The proposed risk score might be useful for risk-adapted treatment in the future.

MULTIDRUG RESISTANCE IN LEUKEMIAS AND ITS REVERSAL

Drug resistance often results in failure of anticancer chemotherapy in leukemias. Several mechanisms of drug resistance are known with multidrug resistance (MDR) being the best characterized one. MDR can be due to enhanced expression of certain genes (MDR1, MRP or LRP), alterations in glutathione-S-transferase activity or GSH levels and to reduction of the amount or the activity of topoisomerase II. Here we review the current status of the clinical significance of the various mechanisms of MDR in leukemias and also discuss possibilities for the reversal of MDR. MDR1 gene expression has been seen in many leukemias, notably in acute myeloid leukemia (AML) and blast crisis of chronic myeloid leukemia. Both MDR1 RNA and P-glycoprotein expression of the leukemic cells have been shown to correlate with poor clinical outcome in AML. However, preliminary results indicate that the MRP gene as well as the LRP gene can be expressed in AML. Thus, drug resistance in leukemias appears to be multifactorial. P-glycoprotein-mediated MDR can be reversed by several drugs. These resistance modifiers are currently evaluated with regard to their clinical efficacy. Despite some encouraging results, reversal of drug resistance and subsequent improvement in clinical outcome remains to be shown.

MRP Expression in Acute Myeloid Leukemia

To determine the clinical significance of the multidrug resistance protein (MRP) in patients with de novo AML, we have studied MRP expression of leukemic cells at diagnosis and its association with clinical outcome in 127 patients. MRP expression was determined by immunocytochemistry by means of monoclonal antibodies QCRL-l/QCRL-3. MRP expression was low, intermediate and high in 30%, 46% and 24% of the patients, respectively. MRP expression was independent of age and sex of the patients, white blood cell count, FAB subtype, serum lactate dehydrogenase levels and karyotype aberrations. MRP expression had no impact on response to induction chemotherapy. The complete remission rates were 75%, 70% and 64% for patients with low, intermediate and high expression, respectively. Patients with intermediate or high MRP expression showed a trend toward shorter overall survival (p=0.09) as compared to patients with low MRP expression. MRP does not predict for response to induction chemotherapy but intermediate or high MRP expression might be associated with shorter overall survival of the patients.

Immunocytochemical detection of the multidrug resistance-associated protein and P-glycoprotein in acute myeloid leukemia: impact of antibodies, sample source and disease status

Immunocytochemical detection of the expression of the MRP gene and the MDR1 gene in clinical specimens might be affected by several factors. Thus, we studied the impact of monoclonal antibodies, sample source (peripheral blood vs bone marrow) and disease status on the expression of multidrug resistance-associated protein (MRP) as well as P-glycoprotein (P-gp) in leukemic cells of patients with acute myeloid leukemia (AML). MRP expression was determined by means of anti-MRP antibodies (QCRL-1, QCRL-3, QCRL-1/QCRL-3 or MRPr1). In the case of P-gp, monoclonal antibodies C219 and MRK16 were used. High MRP expression ranged from 5 to 35% and high P-gp expression from 5 to 14% of the specimens. A fair correlation between results obtained with QCRL-1/QCRL-3 and those obtained with MRPr1, as well as a moderate correlation between C219 and MRK16, were seen. MRP and P-gp expression of peripheral blood blasts were similar to those of bone marrow blasts in the majority of cases. The degrees of MRP expression at the time of diagnosis were also similar to the degrees of expression at relapse, albeit an analysis of sequential MRP expression in 13 patients indicated an increase of expression at relapse in six patients as compared to the time of diagnosis.

Comparison of Technetium-99m-MIBI imaging with MRI for detection of spine involvement in patients with multiple myeloma

BackgroundRecently, radiopharmaceutical scanning with Tc-99m-MIBI was reported to depict areas with active bone disease in multiple myeloma (MM) with both high sensitivity and specificity. This observation was explained by the uptake of Tc-99m-MIBI by neoplastic cells. The present investigation evaluates whether Tc-99m-MIBI imaging and magnetic resonance imaging (MRI) perform equally well in detecting myelomatous bone marrow lesions.MethodsIn 21 patients with MM, MRIs of the vertebral region TH12 to S1 and whole body scans with Tc-99m-MIBI were done.ResultsTc-99m-MIBI scanning missed bone marrow infiltration in 43 of 87 vertebrae (50.5%) in which MRI showed neoplastic bone marrow involvement. In patients with disease stage I+II, Tc-99m-MIBI scanning was negative in all of 24 vertebrae infiltrated according to MRI. In patients with disease stage III, Tc-99m-MIBI scanning detected 44 of 63 (70%) vertebrae involved by neoplastic disease.ConclusionTc-99m-MIBI scanning underestimated the extent of myelomatous bone marrow infiltration in the spine, especially in patients with low disease stage.

The lung resistance protein (LRP) predicts poor outcome in acute myeloid leukemia.

To determine the clinical significance of the lung resistance protein (LRP) in acute myeloid leukemia (AML), we have studied LRP expression of leukemic blasts and its association with clinical outcome in patients with de novo AML. LRP expression of leukemic blasts was determined by immunocytochemistry by means of monoclonal antibody LRP-56. LRP expression at diagnosis was detected in 31 out of 86 (36%) patients and correlated with white blood cell count (p = 0.01). The complete remission rate of induction chemotherapy was 72% for all treated patients (n = 82). The complete remission rate was 81% for patients without LRP expression but only 55% for patients with LRP expression (p = 0.01). Overall survival and disease-free survival were estimated according to Kaplan-Meier in 82 and 59 patients, respectively. At a median follow-up of 16 months, median overall survival was 17 months for LRP-negative patients but only 8 months for LRP-positive patients (p = 0.006). Disease-free survival was 9 months for LRP-negative patients and 6 months for LRP-positive patients (p = 0.078). Thus LRP predicts for poor outcome indicating that the LRP gene is a clinically relevant drug resistance gene in AML.

[Biomarkers - the way towards individualized chemotherapy in non-small cell lung cancer (NSCLC)].

SummaryTumor biology is increasingly important when choosing the optimal therapy for patients with non-small cell lung cancer (NSCLC). A number of potential biomarkers is under investigation in the hope that it will be possible to identify markers that assist in the selection of patients for specific therapies in the future. Patients with an elevated DNA repair capacity, indicated by an increased tumoral expression of excision repair cross complementation group-1 (ERCC1) or ribonucleotid reductase subunit M1 (RRM1) may benefit less from cisplatin-based and gemcitabine-based chemotherapy, respectively. Overexpression of the cell cycle regulator p27 affects response to various anticancer drugs and increased levels of class III β-Tubulin are associated with taxane resistance. Promising results so far suggest that customized therapy for individual patients with the help of predictive biomarkers is possible and it is likely that this strategy will improve treatment of NSCLC in the future.ZusammenfassungErkenntnisse aus der Tumorbiologie beeinflussen vermehrt therapeutische Entscheidungen in der Behandlung des nichtkleinzelligen Bronchialkarzinoms (NSCLC). Eine Reihe von potentiellen Biomarkern wird derzeit mit der Hoffnung untersucht, dass diese zukünftig bei der Selektion von Patienten für die optimale Therapie hilfreich sein könnten. Patienten mit einer erhöhten DNA-Reparaturkapazität, angezeigt durch eine erhöhte Expression von ERCC1 (excision repair cross complementation group-1) oder RRM1 (ribonucleodid reductase subunit M1), haben ein schlechteres Ansprechen auf cisplatin- oder gemcitabinhältige Chemotherapie. Eine Überexpression des Zellzyklusregulators p27 führt zu einer Resistenz gegen verschiedene Zytostatika und eine erhöhte Expression von Klasse III β-Tubulin ist mit Taxanresistenz assoziiert. Aufgrund bisheriger, viel versprechender Ergebnisse sollte eine individuell angepasste Chemotherapie mit Hilfe von prädiktiven Biomarkern möglich sein und könnte zu einer weiteren Verbesserung der Behandlung des NSCLC beitragen.

Biomarker – der Weg zur individualisierten Chemotherapie beim nicht-kleinzelligen Bronchialkarzinom

SummaryTumor biology is increasingly important when choosing the optimal therapy for patients with non-small cell lung cancer (NSCLC). A number of potential biomarkers is under investigation in the hope that it will be possible to identify markers that assist in the selection of patients for specific therapies in the future. Patients with an elevated DNA repair capacity, indicated by an increased tumoral expression of excision repair cross complementation group-1 (ERCC1) or ribonucleotid reductase subunit M1 (RRM1) may benefit less from cisplatin-based and gemcitabine-based chemotherapy, respectively. Overexpression of the cell cycle regulator p27 affects response to various anticancer drugs and increased levels of class III β-Tubulin are associated with taxane resistance. Promising results so far suggest that customized therapy for individual patients with the help of predictive biomarkers is possible and it is likely that this strategy will improve treatment of NSCLC in the future.ZusammenfassungErkenntnisse aus der Tumorbiologie beeinflussen vermehrt therapeutische Entscheidungen in der Behandlung des nichtkleinzelligen Bronchialkarzinoms (NSCLC). Eine Reihe von potentiellen Biomarkern wird derzeit mit der Hoffnung untersucht, dass diese zukünftig bei der Selektion von Patienten für die optimale Therapie hilfreich sein könnten. Patienten mit einer erhöhten DNA-Reparaturkapazität, angezeigt durch eine erhöhte Expression von ERCC1 (excision repair cross complementation group-1) oder RRM1 (ribonucleodid reductase subunit M1), haben ein schlechteres Ansprechen auf cisplatin- oder gemcitabinhältige Chemotherapie. Eine Überexpression des Zellzyklusregulators p27 führt zu einer Resistenz gegen verschiedene Zytostatika und eine erhöhte Expression von Klasse III β-Tubulin ist mit Taxanresistenz assoziiert. Aufgrund bisheriger, viel versprechender Ergebnisse sollte eine individuell angepasste Chemotherapie mit Hilfe von prädiktiven Biomarkern möglich sein und könnte zu einer weiteren Verbesserung der Behandlung des NSCLC beitragen.