Ernst Schering Foundation symposium proceedings最新文献

The main function of mature T cells is to recognize and respond to foreign antigens by a complex activation process involving differentiation of the resting cell to a proliferating lymphoblast actively secreting immunoregulatory lymphokines or displaying targeted cytotoxicity, ultimately leading to recruitment of other cell types and initiation of an effective immune response. In order to understand the physiology and pathophysiology of T lymphocytes, it is necessary to decode the biochemical processes that integrate signals from antigen, cytokine, integrin and death receptors. The principal upon which our work is based is to explore and identify gene products of distinct members of the AGC family of protein serine/threonine kinases as key players mediating cell growth regulation. Given the established important role of PKC theta as regulator of T cell fate and knowing that several other PKC isotypes are also expressed in T cells at a high level, we now summarize the physiological and non-redundant functions of PKC alpha, beta, delta, epsilon, zeta and theta isotypes in T cells. This review describes the current knowledge of the physiological and non-redundant functions of the PKC gene products in T cells.

Progesterone is an essential regulator of normal female reproductive function, yet recent studies on the use of progestins in hormone replacement therapy have clearly implicated progestins in breast cancer development, a disease initiated early in life at a time of frequent exposure to cycling ovarian hormones. The effects of progesterone are mediated by two distinct nuclear receptor proteins, PRA and PRB. In normal breast PRA and PRB are co-expressed at similar levels in luminal epithelial cells, suggesting that both proteins are required to mediate physiologically relevant progesterone signalling. However, early in breast carcinogenesis PRA:PRB expression is disrupted, resulting in frequent predominance of one isoform. Unbalanced expression of PRA and PRB results in altered hormonal response and aberrant targeting of genes that are not normally progestin-regulated, principally those involved in morphological changes and disruptions of the actin cytoskeleton, and in migration. Movement of PR into discrete nuclear domains, or foci, is a critical step in normal PR transcriptional activity that appears to be aberrant in cancers and likely related to alterations in nuclear morphology, gene expression and cell function associated with tumour cells. Given that exogenous progestins are consumed by millions of women worldwide in the form of hormone replacement therapy and oral contraceptives, it is vital to better understand the mechanisms of progesterone action in the breast.

There exists at present an urgent desire for better biomarkers, especially in the context of pharmaceutical drug development and in the detection and management of disease. Many researchers in the area of biomarker discovery and development have turned to the "-omics" sciences as a way of addressing these needs. Metabolic profiling, or metabonomics, defines the metabolic phenotype and offers a source of novel biomarkers that have better potential to translate effectively. This review will discuss the broad philosophy and motivations behind metabonomics, and illustrate the case with applications relevant to pharmaceutical development and patient management. Particular focus will be paid to the potential of metabonomics to contribute to biomarker discovery in toxicology and cancer research.

Increased metabolism has been found to be one of the most prominent features of malignant tumors. This property led to the development of tracers for the assessment of glucose metabolism and amino acid transport and their application for tumor diagnosis and staging. Prominent examples are fluorodeoxyglucose, methionine and tyrosine analogs, which have found broad clinical application. Since quantitative procedures are available, these techniques can also be used for therapy monitoring. Another approach may be based on the noninvasive detection of apoptosis with tracers for phosphatidyl-serine presentation and/or caspase activation as surrogate markers for therapeutic efficacy. Finally, the evaluation of hypoxia with nitroimidazoles may be a valuable tool for prognosis and therapy planning.

Estrogen and progesterone play a critical role in normal and neoplastic development of the mammary gland. A long duration of estrogen and progesterone exposure is associated with increased breast cancer risk, and a short duration of the same doses of these hormones is associated with a reduced breast cancer risk. The protective effects of estrogen and progesterone have been extensively studied in animal models. Several studies have demonstrated that these hormones induce persistent and long-lasting alterations in gene expression in the mammary epithelial cells. In the experiments discussed herein, the protective effect of estrogen and progesterone is shown to occur in genetically engineered mice (the p53-null mammary gland). The protective effect is associated with a decrease in cell proliferation. The effects of hormones seem to manifest as a delay in premalignant progression. In the nontumor-bearing glands of hormone-treated mice, premalignant foci are present at the time the control glands are actively developing mammary tumors. If the hormone-treated cells are transplanted from the treated host to the untreated host, the cells resume their predetermined tumorigenic potential. The protective effect reflects both host-mediated factors (either stroma-determined or systemic factors) and mammary epithelial intrinsic changes. If normal, untreated p53 cells are transplanted into a host that has been previously treated with a short dose of hormones, the cells exhibit a significant delay in tumorigenesis. The relative contributions of host-mediated factors and mammary cell intrinsic factors remain to be determined. Current studies are moving this research area from the biological to the molecular realm and from the rodent models to human studies and offer the potential for directing prevention efforts at specific molecular targets.

Migration is an essential function of immune cells. It is necessary to lead immune cell precursors from their site of generation to the places of maturation or function. Cells of the adaptive immune system also need to interact physically with each other or with specialized antigen presenting cells in lymphatic tissues in order to become activated. Thereby a complex series of controlled migration events, adhesive interactions and signalling responses is induced. Finally cells must be able to leave the activating tissues and re-enter the bloodstream from which they extravasate into inflamed tissue sites. Cells of the innate immune system can function directly without the need for previous activation. However, these cells have to adapt their function to a panoply of pathogens and environmental niches which can be invaded. The current review highlights the central aspects of cellular dynamics underlying adaptive and innate cellular immunity. Thereby a focus will be put on recent results obtained by microscopic observation of live cells in vitro or by intravital 2-photon microscopy in live animals.

Studies of drug action classically assess biochemical activity in settings which typically contain the isolated target only. Recent technical advances in mass spectrometry-based analysis of proteins have enabled the quantitative analysis of sub-proteomes and entire proteomes, thus initiating a departure from the traditional single gene--single protein--single target paradigm. Here, we review chemical proteomics-based experimental strategies in kinase drug discovery to analyse quantitatively the interaction of small molecule compounds or drugs with a defined sub-proteome containing hundreds of protein kinases and related proteins. One novel approach is based on 'Kinobeads'--an affinity resin comprised of a cocktail of immobilized broad spectrum kinase inhibitors--to monitor quantitatively the differential binding of kinases and related nucleotide-binding proteins in the presence and absence of varying concentrations of a lead compound or drug of interest. Differential binding is detected by high throughput and sensitive mass spectroscopy techniques utilizing isobaric tagging reagents (iTRAQ), yielding quantitative and detailed target binding profiles. The method can be applied to the screening of compound libraries and to selectivity profiling of lead compounds directly against their endogenously expressed targets in a range of cell types and tissue lysates. In addition, the method can be used to map drug-induced changes in the phosphorylation state of the captured sub-proteome, enabling the analysis of signalling pathways downstream of target kinases.