Non-sufficient cell cycle control as possible clue for the resistance of human malignant glioma cells to clinically relevant treatment conditions

High-resolution flow cytometry: a suitable tool for monitoring aneuploid prostate cancer cells after TMZ and TMZ-BioShuttle treatment

If metastatic prostate cancer gets resistant to antiandrogen therapy, there are few treatment options, because prostate cancer is not very sensitive to cytostatic agents. Temozolomide (TMZ) as an orally applicable chemotherapeutic substance has been proven to be effective and well tolerated with occasional moderate toxicity especially for brain tumors and an application to prostate cancer cells seemed to be promising. Unfortunately, TMZ was inefficient in the treatment of symptomatic progressive hormone-refractory prostate cancer (HRPC). The reasons could be a low sensitivity against TMZ the short plasma half-life of TMZ, non-adapted application regimens and additionally, the aneuploid DNA content of prostate cancer cells suggesting different sensitivity against therapeutical interventions e.g. radiation therapy or chemotherapy. Considerations to improve this unsatisfying situation resulted in the realization of higher local TMZ concentrations, sufficient to kill cells regardless of intrinsic cellular sensitivity and cell DNA-index. Therefore, we reformulated the TMZ by ligation to a peptide-based carrier system called TMZ-BioShuttle for intervention. The modular-composed carrier consists of a transmembrane transporter (CPP), connected to a nuclear localization sequence (NLS) cleavably-bound, which in turn was coupled with TMZ. The NLS-sequence allows an active delivery of the TMZ into the cell nucleus after transmembrane passage of the TMZ-BioShuttle and intra-cytoplasm enzymatic cleavage and separation from the CPP. This TMZ-BioShuttle could contribute to improve therapeutic options exemplified by the hormone refractory prostate cancer. The next step was to syllogize a qualified method monitoring cell toxic effects in a high sensitivity under consideration of the ploidy status. The high-resolution flow cytometric analysis showed to be an appropriate system for a better detection and distinction of several cell populations dependent on their different DNA-indices as well as changes in proliferation of cell populations after chemotherapeutical treatment.

Engineering of clinical glioma treatment: prediction of pro-invasive molecular events in treated gliomas

The diffusely infiltrative nature of malignant gliomas is the main obstacle to successful treatment approaches. Advanced simulation models of the in vivo response to therapy conditions are expected to improve malignant glioma treatment substantially. In parallel experiments, human malignant glioma cells underwent either radiation or chemotherapy treatment (chemotreatment) with temozolomide alone, or combined chemoradiation. Cells were treated according to diverse, clinically relevant, therapeutic algorithms. Quantitative 'real-time' polymerase chain reaction (PCR) measurements were performed for target genes, namely vascular endothelial growth factor, p53, and cyclooxygenase-2, which allow a comparative evaluation of pro-invasive molecular events in treated gliomas. The proof-of-principle study simulated variable intratumoural regional conditions. Pro-invasive molecular patterns were strongly dependent on the treatment algorithm, cellular density, and drug delivery. The highest pro-invasive potential was demonstrated for simulated peripheral regions under continued chemoradiation. This result strongly supports the clinical observations of increased aggressiveness and relatively poor response to second-line therapies in post-operatively chemoradiation-treated malignant gliomas at the time of relapse. Individualized and potentially the most effective treatment algorithms can be designed using established gene expression patterns applied on primary cell cultures obtained from individual patients. Individual drug toxicity and response to anti-cancer therapy can be predicted.

Up-regulation of vimentin expression in low-density malignant glioma cells as immediate and late effects under irradiation and temozolomide treatment

Nervous system tumors are one of the leading causes of cancer related death. Specific mechanisms facilitating the invasive behavior of gliomas remain obscure. Advanced simulation models of the in vivo response to therapy conditions should potentially improve malignant glioma treatment. Expressional profiling of vimentin--one of reliable pro-invasive tumor makers--in those simulation models was the goal of this study, in order to estimate a pro-invasive response of surviving malignant glioma cells under clinically relevant therapeutic conditions. Human U87-MG malignant glioma cells were used. These cells are characterized by the wild p53-phenotype, which is relevant for the majority of primary malignant glioblastomas. Experimental design foresaw the cells to undergo either irradiation or chemo-treatment with temozolomide alone, or combined treatment. Expression profiling of vimentin was performed by quantitative "Real-Time"-PCR under all treatment conditions simulating diverse tumor regions. Here we demonstrated that vimentin expression patterns in human malignant glioma cells strongly depend on cellular density, algorithms of drug delivery and chemo/radio treatment. Substantial differences were recognized between immediate and late therapy effects. Significant increase in vimentin expression levels was detected particularly in low-density cell cultures under durable treatment with constant concentration levels of temezolomide. Simulation of variable intratumoral regional conditions (central intratumoral regions vs. disseminated malignant cells in peripheral regions) demonstrated differential response of vimentin expression in malignant glioma cell cultures treated under clinically relevant conditions. Slight ebbing of expression levels as late effects of the treatment in confluent cultures may correspond to necrotic processes clinically observed in central intratumoral regions. Contrary, in disseminated malignant cells of peripheral regions therapy resulted in vimentin-inducing effects. This is in agreement with the clinical observations of an increased aggressiveness and malignancy grade of post-operatively chemo/radio-treated malignant gliomas.

Cell cycle checkpoints: the role and evaluation for early diagnosis of senescence, cardiovascular, cancer, and neurodegenerative diseases

Maintenance of genomic integrity is critical for prevention of a wide variety of adverse cellular effects including apoptosis, cellular senescence, and malignant cell transformation. Under stress conditions and even during an unperturbed cell cycle, checkpoint proteins play the key role in genome maintenance by and mediating cellular response to DNA damage, and represent an essential part of the "cellular stress response proteome". Intact checkpoint signal transduction cascades check the presence of genome damage, trigger cell cycle arrest, and forward the information to the protein core of cell cycle machinery, replication apparatus, repair, and/or apoptotic protein cores. Genetic checkpoint defects lead to syndromes that demonstrate chromosomal instability, increased sensitivity to genotoxic stress, tissue degeneration, developmental retardation, premature aging, and cancer predisposition that is most extensively studied for the ATM-checkpoint mutated in Ataxia telangiectasia. Tissue specific epigenetic control over the function of cell cycle checkpoints can be, further, misregulated by aberrant DNA methylation status. The consequent checkpoint dysregulation may result in tissue specific degenerative processes such as degeneration and calcification of heart aortic valves, diabetic cardiomyopathy, hyperhomocysteinemic cerebrovascular, peripheral vascular and coronary heart diseases, neurodegenerative disorders (Alzheimer and Parkinson diseases, amyotrophic lateral sclerosis, glaucoma), and accelerated aging frequently accompanied with cancer. This review focuses on the checkpoints shown to be crucial for unperturbed cell cycle regulation, dysregulation of which might be considered as a potential molecular marker for early diagnosis of and therapy efficiency in neurodegenerative, cardiovascular and cancer diseases. An application of the most potent detection technologies such as "Disease Proteomics and Transcriptomics" also considered here, allows a most specific selection of diagnostic markers.