Biomedical subjects

T Efferth

Publications and source records attributed to T Efferth.

69 records · Page 4Linked to original sources

PubMedDate not supplied

Protein expression profile of newly diagnosed acute lymphoblastic leukemia in children developing relapses.

The purpose of this investigation was to evaluate the expression profile of proteins involved in children with newly diagnosed acute lymphoblastic leukemia (ALL) children who are developing relapses. For this reason, the expressions of 10 proteins including proto-oncogene and tumor suppressor gene products, proliferative factors and resistance parameters in 104 initial cases of childhood ALL were analyzed and the proteins correlated with ALL patients who experienced relapses. Applying immunocytochemical assays, we found that 4 out of the 10 parameters revealed a relationship to developing relapses (Fisher's exact tests). These were the oncogene product Fos (p=0.002), the drug resistance proteins glutathione S-transferase (p=0.008) and P-glycoprotein (P-pg/MDR1) (p=0.07) and protein kinase C (p=0.01). By means of hierarchical cluster analysis, we were able to show that the patients could be separated according to their protein expression profile into clusters consisting of patients whose ALL relapsed later and of patients who did not show relapses in the future.

Child↗

PubMedDate not supplied

Leptin contributes to the protection of human leukemic cells from cisplatinum cytoxicity.

Leptin (ob gene) and its cognate receptor (obr) are relevant for fat metabolism. Obr shares homology with the IL-6 signal transducer gp130 and is expressed in hematopoietic cells. Since cytokines and growth factors regulate both hematopoiesis and response to chemotherapy, we tested the hypothesis of whether leptin protects leukemic cells from cytotoxicity of cisplatinum. Antisense phosphorothioate oligodeoxynucleotides (ODNs) and antisense peptide nucleic acids (PNAs) complementary to the obr gene were first tested for their growth inhibitory activity in obr expressing leukemic cells. Liposome-mediated transfection of ODNs (1-2 microM) or PNAs (0.01-1 microM) inhibited growth up to 50%. Combination treatments of cisplatinum and 0.01 microM PNA reduced growth more than cisplatinum alone. Vice versa, recombinant human leptin (rhL) diminished cisplatinum-induced growth inhibition. Finally, we investigated whether rhL affects cisplatinum-induced DNA damage and repair in the housekeeping gene beta-actin by means of real time TaqMan polymerase chain reaction. RhL reduced DNA damage and increased DNA repair. The effects are, however, modest and leptin is probably not the only player in the armory of growth factors which affect drug resistance.

Antineoplastic Agents↗

PubMedDate not supplied

Damage of the kinesin heavy chain gene contributes to the antagonism of cisplatin and paclitaxel.

Paclitaxel (TAX) and cisplatin (DDP) rank among the most promising anti-neoplastic agents for the treatment of epithelial cancer. Pre-clinical and clinical data show that the cytotoxicity resulting from the combined use of TAX and DDP is governed by the order (TAX prior DDP) > (DDP prior TAX). Since this also occurs with DNA damaging agents other than DDP, damage of a sensitivity gene may be of importance. Recently, a role of kinesin heavy chain (KHC) was uncovered for the cytotoxicity of many natural drug derivatives by use of genetic suppressor elements (Gudkov et al. (1994) Proc. Natl. Acad. Sci. USA, 91, 3744-3748). We first confirmed the dependency on the order of addition for TAX and DDP in human leukemic K562 cells taking apoptotic fraction and cell growth as endpoints. We then inhibited KHC gene expression by antisense oligodeoxy-nucleotides or KHC protein function by monoclonal antibody SUK4. Both approaches led to a reduced cytotoxicity of TAX indicating that KHC may confer sensitivity to TAX. Using a PCR-stop assay, we found that DDP indeed caused dose related DNA damage in the KHC gene. There was more DNA damage in the KHC gene than in four other genes (AFP, G6PD, MDR1, TCR-delta). Increasing doses of DDP down-regulated KHC mRNA expression more than of G6PD. There may therefore be a role of KHC for the use of TAX and DDP in combination.

Antineoplastic Agents↗

PubMedDate not supplied

Differential expression of the drug resistance markers DNA topoisomerase II alpha and glutathione S-transferase-pi in the histological compartments of Wilms' tumors.

More than 80% of the patients presenting with Wilms' tumor can be cured today. Some patients, however, fail to respond to chemotherapy. The objective of this study was to analyze the immunohistochemical distribution of two markers of cytostatic drug resistance, e.g. DNA topoisomerase II alpha (Topo II alpha) and glutathione S-transferase-pi (GST-pi) in 23 Wilms' tumor patients who had undergone an operation between 1984 and 1997. Eight patients had stage I disease, seven stage II, three stage III, four stage IV, and one stage V disease. Five tumors showed high malignancy histology. Investigations were carried out on formalin-fixed and paraffin-embedded tissue sections using the indirect immunoperoxidase method. Topo II alpha was predominantly present in the epithelial components of the specimens. It was more frequently found in anaplastic tumors. There was no difference in the presence of Topo II alpha in the epithelial components between specimens derived from treated and untreated patients. Topo II alpha was, however, less expressed in the blastemal and stromal elements of specimens after preoperative treatment. If GST-pi was present, it was confined to the epithelial components except for one case. While no expression of GST-pi was found in preoperatively untreated Wilms' tumors, it was present in epithelial compartments in 57% of tumors after chemotherapy. In conclusion, preoperative chemotherapy led to compartment-specific alterations in the expression levels of both markers indicating a contribution to treatment response of Wilms' tumors.

Antigens, Neoplasm↗

PubMedDate not supplied

Differential expression of the heat shock protein 70 in the histological compartments of nephroblastomas.

Nephroblastomas (Wilms' tumors) are curable with survival rates above 80%. Nevertheless, some tumors fail to respond to therapy and those patients have a poor prognosis. Prognostic factors for nephroblastomas have still not been satisfactorily explored. In an effort to unravel molecular markers for non-responding nephroblastomas, we investigated by means of immunohistochemistty the expression of heat-shock protein 70 (HSP70) in formalin-fixed and paraffin-embedded tissue samples from 32 children afflicted with nephroblastoma. The results were validated using real-time RT-PCR. HSP70 expression was confined to blastemal and epithelial components, while the tumor stroma was negative. HSP70 expression was greater, if the tumors had been chemotherapeutically treated prior to operation, indicating that cytostatic drugs induce HSP70. Furthermore, high HSP70 expression was confined to tumors from children who survived, whereas tumors from dead patients were negative or weakly-positive for HSP70. Though the number of cases analyzed was small, they provide an indication that HSP70 expression may be of prognostic value.

Adolescent↗

PubMedDate not supplied

Induction of apoptosis, depletion of glutathione, and DNA damage by extracorporeal photochemotherapy and psoralen with exposure to UV light in vitro.

Extra corporeal photochemotherapy (ECPT) is a novel treatment for disorders caused by aberrant T lymphocytes. The effects of ECPT were investigated in mononuclear cells (MNC) of six patients suffering from either Sezary syndrome, mycosis fungoides, systemic sclerosis, pemphigus vulgaris or Hodgkin's disease. ECPT caused moderate to severe induction of apoptosis and depletion of glutathione in the MNC of two out of these six patients. The MNC were then treated with 8-methoxypsoralen (8-MOP) and UV light in vitro and analyzed for apoptosis and glutathione levels. 8-MOP and UV light induced a profile of cellular alterations that is similar to ECPT. In addition, we measured DNA damage by means of a PCR-based methodology. As exemplified by the T-cell receptor-delta and glucose-6-phosphate dehydrogenase genes, DNA damage correlated with induction of apoptosis and depletion of glutathione. It is, therefore, reasonable to propose that UV-induced glutathione depletion contributes to DNA lesions which ultimately account for the onset of apoptosis.

Adult↗

PubMedDate not supplied

MDR1 single nucleotide polymorphism C3435T in normal colorectal tissue and colorectal carcinomas detected by MALDI-TOF mass spectrometry.

Single nucleotide polymorphisms (SNPs) may contribute to the malignant process and may show clinicopathological importance as prognostic markers. The multidrug resistance gene MDR1 encodes a membrane transporter which confers cytostatic drug resistance in tumors and protects normal tissues from xenobiotics. We analyzed the C3435T SNP in the MDR1 gene which is associated with altered cellular drug uptake in matched tumor and normal tissues of 45 patients suffering from colorectal carcinoma. We have developed a highly sensitive matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) method to survey the C3435T polymorphism in PCR-amplified fragments of the MDR1 gene. Thirteen patients were homozygous for C/C (29%), 15 were heterozygous (33%) and 17 were homozygous for T/T (38%). None of the tumor samples showed an altered SNP compared to their matched normal tissue samples. As analyzed by the Kruskall-Wallis test, none of the clinicopathological parameters was significantly associated with homo- or heterozygosity. The combination of PCR, allele-specific primer extension reactions and MALDI-TOF-MS offers a promising alternative method for genotyping the MDR1 gene especially for heterozygous situations. The inherent advantages of MALDI-TOF-MS based genotyping include its high molecular resolution, high signal-to-noise-ratios and reproducibility, combined with an excellent sensitivity. As none of the tumor samples showed an altered state compared to their matched normal tissue samples, the genotypic frequency of this polymorphism seems not to be altered during colorectal tumorigenesis.

Adult↗

PubMedDate not supplied

Oncoprotein (c-myc, c-erbB1, c-erbB2, c-fos) and suppressor gene product (p53) expression in squamous cell carcinomas of the lung. Clinical and biological correlations.

The expression of the protooncogene encoded proteins (c-erbB1, c-erb B2, c-myc, c-fos) and the suppressor gene product p53 was analyzed in 81 human squamous cell carcinomas of the lung and correlated with clinical parameters of the patients (patient survival, presence of metastases and tumor stage) and with biological characteristics of the tumors (tumor growth in nude mice, DNA-ploidy, proliferative activity, drug-resistance and P-glycoprotein or gluathione S-transferase expression). By means of immunohistochemistry, expression of c-erbB1 oncoprotein (EGF-receptor) was detected in 79% of the tumors, c-erbB2 (c-neu) proteins in 35%, c-myc proteins in 48%, c-fos proteins in 41%, and p53 in 43% of the tumors. Patients with c-erbB1 positive tumors had a poor prognosis (p = 0.021). In addition, these tumors were more frequently drug resistant (p = 0.0067). A significant correlation between the growth of the squamous lung carcinomas in nude mice and c-fos oncoprotein expression was demonstrated (p = 0.017). Therefore, EGF-receptor and c-fos products may serve as prognostic factors for the aggressiveness of squamous cell carcinomas of the lung and for the response of these tumors to chemotherapy. No significant correlation was found between the expression of the c-erbB1 or c-fos gene products and stage, metastasis and DNA-ploidy. In contrast to these results, no relationship was found between c-neu or c-myc gene products expression and any of the clinical or biological parameters examined. Aneuploid squamous cell carcinomas of the lung expressed p53 more frequently than diploid tumors (p = 0.027). However, there was no significant difference between p53 expression and stage, survival of patients, metastasis, growth of the tumors in nude mice, proliferative activity and drug-resistance of the tumors.

Carcinoma, Squamous Cell↗

PubMedDate not supplied

Expression of several resistance mechanisms in untreated human kidney and lung carcinomas.

Thirty human renal cell carcinomas and 94 non-small cell lung carcinomas of previously untreated patients were analyzed for the presence of P-glycoprotein, glutathione S-transferase-pi and topoisomerase II by means of immunohistochemistry. In the renal cell carcinomas investigated, two resistance markers were seen in 53% and three resistance markers in 36% of the cases. In only three tumors was one resistance mechanism observed. In the 94 non-small cell lung carcinomas 34% had two and 20% three resistance mechanisms, whereas 24% of the tumors revealed only one resistance mechanism. For determining the resistance of the tumors against drugs an in vitro short-term test was used. Only 12% of the sensitive lung tumors had more than one resistance mechanism, whereas 70% of the resistant tumors did. Thus a significant relationship exists between the resistance measured in vitro and the overexpression of P-glycoprotein or glutathione S-transferase-pi and the down-regulation of topoisomerase II.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMedDate not supplied

Expression of protein kinase C in human renal cell carcinoma cells with inherent resistance to doxorubicin.

The expression of protein kinase C (PKC) was analyzed in 18 primary cell cultures of human renal cell carcinomas by means of immunocytochemistry. We found that a high PKC expression significantly correlates with both resistance to doxorubicin and high P-glycoprotein expression. These data support the hypothesis that PKC is involved in inherent drug-resistance by phosphorylation and regulation of P-glycoprotein.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMedDate not supplied

Reversing multidrug resistance in L1210 tumor cells by hycanthone or chlorophenoxamine in vitro and in vivo.

In the presence study we demonstrated that hycanthone and chlorophenoxamine can modulate the resistance of multidrug resistant (MDR) murine L1210 leukemia tumor lines in vitro and in vivo. The circumvention of MDR by hycanthone and chlorophenoxamine in vitro was demonstrated by a short-term test using tritiated nucleic acid precursors and by flow cytometrical measurement of accumulation of rhodamine 123. Furthermore, we treated mice bearing resistant L1210 ascites cells with doxorubicin and hycanthone or chlorophenoxamine. Hycanthone in combination with doxorubicin significantly inhibited tumor growth. We also found an improved therapeutic effect of doxorubicin plus chlorophenoxamine. Our results in vitro and in vivo indicate that hycanthone and chlorophenoxamine might be appropriate tools for the circumvention of MDR in human tumors.

Animals↗

PubMedDate not supplied

Reciprocal correlation between expression of P-glycoprotein and accumulation of rhodamine 123 in human tumors.

The aim of this investigation was to determine whether a correlation exists between expression of the multi-drug-resistance associated P-glycoprotein 170 (P-gp170) and the accumulation of rhodamine 123 in human tumors. We investigated a panel of inherently resistant cell lines originating from human kidney tumor specimens and chemotherapeutically pretreated leukemias. The expression of P-gp170 was evaluated by means of two different immunohistological methods using two monoclonal antibodies against P-gp170. We found a significant reciprocal correlation between expression of P-gp170 and accumulation of rhodamine 123. This supports the view that P-gp170 might function as efflux pump in human tumors, as previously described for experimental models.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMedDate not supplied

Immunocytochemical detection of a resistance-associated glycoprotein in tissue culture cells, ascites tumors and human tumor xenografts by Mab 265/F4.

The aim of this investigation was to find out whether resistant cells of different tumors can be detected immunocytochemically by the streptavidin-biotin-peroxidase-complex method using the monoclonal antibody 265/F4. This antibody was prepared against the membrane P-glycoprotein of Mr 170 kd from colchicine-resistant CHO cells. For this purpose the acquired resistance of tissue culture cells, ascites tumors and the acquired and inherent resistance of human lung carcinoma xenografts were analyzed. Doxorubicin-resistant S180 cells, daunorubicin-resistant L1210 cells and vincristine-resistant human epidermoid lung carcinoma xenografts showed an intense positive reaction with the monoclonal antibody. In contrast, no specific immunoreactivity was observed with parental (sensitive) tumor cells. These data could eventually provide a prognostic tool for the detection of resistant human tumor cells.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMedDate not supplied

Induced multidrug-resistance in murine sarcoma 180 cells grown in vitro and in vivo and associated changes in expression of multidrug-resistance DNA-sequences and membrane glycoproteins.

The aim of this investigation was to analyze the resistance to doxorubicin and daunorubicin of murine sarcoma 180 cells grown in vitro (monolayer) and in vivo (ascites form). The colchicine-resistant CHO cells were used as controls. A multidrug-resistant phenotype was found in all investigated cell lines. Multidrug resistant cells grown in tissue culture or as ascites tumor cells needed more time to accumulate rhodamine 123 than their sensitive parental cells. In order to evaluate whether the resistant cells show alterations in the plasma membranes, different methods were applied (immunocytochemistry, immunofluorescence, immunoblotting) using the monoclonal antibodies 265/F4 and C 219. These methods all revealed an increased expression of the glycoprotein Mr 170 kd in the multidrug-resistant cell lines. To determine whether multidrug DNA sequences were expressed in the resistant cell lines, slot blots and Northern blots with RNA of sensitive and resistant cells were performed using the clones pDR 7.8 and pcDR 1.5. Elevated RNA levels were detected in all resistant cell lines.

Animals↗

PubMedDate not supplied

Reversal of inherent multidrug-resistance in primary human renal cell carcinoma cell cultures by S 9788.

In a panel of 14 primary cultures of human renal cell carcinomas the reversal of inherent multidrug-resistance by S 9788, a new triazinoaminopiperidine derivative, was analysed. In combination with doxorubicin S 9788 revealed an evident reversal of multidrug resistance in 12 cell cultures. Two cell cultures remained unaffected. An association between reversal and P-glycoprotein (P-170) expression suggests that S 9788 exerts its activity through P-glycoprotein.

ATP Binding Cassette Transporter, Subfamily B, Mem↗