Cell death induction by betulinic acid,ceramide and TRAIL in primary glioblastoma multiforme cells

Summary Background. Glioblastoma multiforme (WHO Grade IV, GBM) is the most malignant brain tumour with a mean survival time of less than one year. Betulinic acid, ceramide and TRAIL (TNF-related apoptosis inducing ligand) represent novel therapeutic agents for potential use in GBM. Method. Primary GBM cells of 21 patients with macroscopically complete tumour resection were tested in vitro for cell death induction by betulinic acid, ceramide, TRAIL and established therapeutics (BCNU, cisplatin, doxorubicin, vincristin and -irradiation). Findings. At peak plasma concentrations (PPC), Betulinic acid, ceramide and TRAIL induced cell death in primary GBM cells at higher rates than established cytotoxic drugs. Specific cell death 75% was observed in 43% (9/21), 38% (8/21), and 19% (4/21) for betulinic acid, ceramide, and TRAIL respectively, while this was only found in 5% (1/21) of -irradiated and cisplatin-treated cells, and in none of the GBM cultures, where BCNU or vincristin were applied in PPC. Conclusion. Due to a markedly improved cell death of GBM cells as compared with established therapeutics, Betulinic acid, ceramide and TRAIL might represent potent substances for future treatment of GBM.     

Detection of disseminated tumour cells as a potential surrogate-marker for monitoring palliative chemotherapy in colorectal cancer patients

In a pilot study the effect of palliative chemotherapy on the detection rates of circulating tumour cells in peripheral venous blood of stage IV colorectal cancer patients was investigated. The results indicate a recruitment of tumour cells during chemotherapy and suggest a poorer survival for tumour cell positive patients. Circulating tumour cells have been shown to be a potential prognostic factor in patients who undergo curative resection for colorectal cancer. The effect of chemotherapy on the detection rates of disseminated tumour cells in blood has not yet been adequately investigated. Objective of this pilot-study was to analyze circulating tumour cells in peripheral venous blood of colorectal cancer patients undergoing chemotherapy in order to evaluate its potential value as a surrogate-marker for predicting clinical outcome after chemotherapy. Our hypothesis was that chemotherapy results in a reduction of the detection rates of circulating tumour cells in colorectal cancer patients. Forty-two Stage IV patients were examined at three different time points before and during palliative chemotherapy for the presence of disseminated tumour cells, using a previously described RT-PCR-assay for cytokeratin 20. 80.1% of the patients showed disseminated tumour cells at least once. Before chemotherapy, patients with multi-organ metastases were positive in 62.5%, patients with locally limited disease in only 14.3%. After the first chemotherapy, the detection rates in the latter group increased to 62.5%, for all patients in the same time from 46.3% to 57.5%. Clinical therapy responders showed an increase in the detection rates from 28.5% before to 71.4% after chemotherapy. In contrast, chemotherapy had no effect on tumour cell detection rates of patients with progressive disease (57% before vs. 60% after therapy). Patients with detected circulating tumour cells showed a shorter overall survival than patients without circulating tumour cells (83 vs. 53 weeks). Clinical therapy responders on average lived only 3 weeks longer than non-responders. In contrast to the original hypothesis, our data suggest a recruiting of circulating tumour cells during chemotherapy in advanced colorectal cancer. Further investigations are needed to clarify the potential role of circulating tumour cells for monitoring chemotherapy in these patients.     

Combined effect of recombinant CD19 x CD16 diabody and thalidomide in a preclinical model of human B cell lymphoma

Combining different treatment strategies offers the possibility of improving treatment results for cancer patients. The aim of our study was therefore to investigate the combination of treatment of established s.c. human B non-Hodgkin's lymphoma in severe immune deficient mice using a recombinant bispecific CD19 x CD16 diabody (targeting natural killer cells to CD19 cells) and the angiogenesis inhibitor thalidomide. Monotherapy with either thalidomide or diabody caused an approximate 50% reduction in tumor growth rate. The combined treatment showed evidence for a synergistic effect resulting in a 74% reduction in median tumor size. In the combined treatment group, two of five animals had complete remissions of their s.c. tumor. These results suggest that a combination treatment with recombinant diabodies and angiogenesis inhibition represents a useful approach in cancer therapy.     

Expression of the heat shock cognate protein HSP73 correlates with tumour thickness of primary melanomas and is enhanced in melanoma metastases

Seeking to identify melanoma-associated genes by comparing gene expression in uncultured primary melanoma specimens with those in nevi, from which melanomas often are known to arise, we applied subtractive suppression hybridization. Generating a subtracted library of candidate genes up-regulated in primary melanomas, this library contained cDNA fragments of the genes encoding heat shock cognate protein (HSP73) and major histocompatibility complex (HLA-DR) which were overexpressed in further 19 independent melanoma resection specimens on cDNA Southern blots when compared to 19 acquired melanocytic nevi. Upon immunohistochemistry, HSP73 protein expression was detected in the cytoplasm of melanoma cells in primary tumours and metastases. In primary melanomas, the proportion of HSP73 protein expressing cells correlated with tumour thickness according to Breslow which was statistically significant. HSP73 immunostaining was stronger in melanoma metastases when compared with acquired melanocytic nevi which was statistically significant. In addition to melanoma, gastric and uterus cancer tissues exhibited higher HSP73 mRNA expression on a matched tumour/normal cDNA array than their normal counterparts which was statistically significant. Participating in the regulation of folding, assembly and degradation of proteins and protecting cellular proteins from the damage caused by cellular stress like hypoxia or changes in cellular pH, elevated HSP73 expression possibly confers proliferative advantage on melanoma cells.     

Melanoma metastasis is associated with enhanced expression of the syntenin gene

Primary cutaneous melanomas and melanoma metastases were examined for differential gene expression using subtractive suppression hybridization in a search for any genes associated with metastasis. Generating a subtracted library of candidate genes up-regulated in melanoma metastases, this library contained 8 different cDNAs, among them a cDNA fragment of the syntenin gene which was overexpressed in further independent melanoma resection specimens on cDNA Southern blots when compared to acquired melanocytic nevi from which melanomas are known to arise. Upon immunohistochemistry, the syntenin protein expression was detected in the cytoplasm of primary cutaneous melanomas and melanoma metastases. Melanoma metastases exhibited higher proportions of tumour cells positive for syntenin immunostaining in comparison to acquired melanocytic nevi or non-metastasizing primary melanomas which was statistically significant. In addition to melanoma, gastric cancer tissues exhibited a higher syntenin mRNA expression on a matched tumour/normal cDNA array than their normal counterparts which was statistically significant. Altogether, we here first describe the detection of the syntenin protein in resection specimens of melanocytic lesions. We conclude that melanoma metastasis is associated with increased expression of the syntenin gene which may participate in signal transduction and cell adhesion via the multifunctional protein-binding properties of its tandem PDZ domains.     

Analysis of reelin as a candidate gene for autism

Genetic studies indicate that chromosome 7q is likely to contain an autism susceptibility locus (AUTS1). We have followed a positional candidate gene approach to identify relevant gene(s) and report here the analysis of reelin (RELN), a gene located under our peak of linkage. Screening RELN for DNA changes identified novel missense variants absent in a large control group; however, the low frequency of these mutations does not explain the relatively strong linkage results on 7q. Furthermore, analysis of a previously reported triplet repeat polymorphism and intragenic single nucleotide polymorphisms, using the transmission disequilibrium test, provided no evidence for association with autism in IMGSAC and German singleton families. The analysis of RELN suggests that it probably does not play a major role in autism aetiology, although further analysis of several missense mutations is warranted in additional affected individuals.