Prolactin Mediated Intracellular Signaling in Mammary Epithelial Cells

Prolactin binds to a member of the cytokine receptor superfamily. The cytoplasmic domain of the prolactin receptor (PrlR)4 displays no enzymatic activity yet prolactin treatment leads to the induction of protein tyrosine phosphorylation. PrlR is associated with JAK2, a protein tyrosine kinase whose activity is stimulated following receptor dimerization. JAK2 subsequently phosphorylates PrlR and other cellular proteins which are recruited to the activated receptor complex. Among the JAK2 substrates is the transcription factor Stat5 whose phosphorylation mediates the transcriptional activation of β-casein gene expression. In this review we discuss the prolactin induced signaling pathways which mediate differentiation of the mammary glan

Psychosocial impact of living-related kidney transplantation on donors and partners

Living-related kidney transplantation (LRKT) is an option for children with end-stage renal failure. In addition to medical concerns, there is uncertainty about the psychological impact of living-related donation on parent donors and families. A survey was conducted on the decision making process and medical and psychosocial consequences of LRKT. Between 1992 and 1999, 20 parents donated a kidney for their child. A questionnaire including 24 items was sent to parent donors and their partners. Nineteen parents and partners responded; the median time after LRKT was 3years. Donors and partners reported an independent decision making process with no significant influence of partners, relatives, or hospital staff. Partners were more concerned about medical problems than donors themselves (P <0.02). Donors and partners cited no medical problems except sustained pain. Both reported an improved personal relationship towards the transplanted child. Donors and partners also cited an improved personal relationship. The vast majority (18/19) of couples still supported the decision for organ donation. In conclusion, there was a high degree of satisfaction with the decision making process in LRKT. The great majority of donors and partners did not report negative medical or psychological consequences. The relationship between donor, partner, and recipient child improved after LRK

Synthesis and Biological Activity of 12-Aza-Epothilones (Azathilones) – Non-Natural Natural Products with Potent Antiproliferative Activity

12-Aza-epothilones ('Azathilones') 1 and 2 have been prepared through ring-closing olefin metathesis or macrolactonization-based cyclization reactions. While RCM of the respective dienes 9 and 12 was found to be very effective and produced macrocyclic olefins with high E selectivity, the subsequent reduction of the 9,10-double bond proved to be unexpectedly difficult and low-yielding. Preparation of azathilone 2 was also accomplished via macrolactonization and this approach was found to be more effective. Compound 2 is a highly potent inhibitor of human cancer cell growth in vitro. The activity of this analog is comparable with that of Epo A, both in terms of cytotoxicity against drug-sensitive human cancer cells as well as its tubulin-polymerizing activity. However, in contrast to Epo A, 2 is considerably less potent against multidrug-resistant cancer cells

The native structure of the activated Raf protein kinase is a membrane-bound multi-subunit complex

Raf is a mitogen-stimulated protein kinase that functions as a component of the signaling cascade that leads to the stimulation of mitogen-activated protein kinase. Here we show that the native structure of Raf is a large multi-subunit protein complex with an apparent mass of 300-500 kDa that interacts with Ras and the mitogen-activated protein kinase kinase Mek. Analysis of the structure of the Raf complex demonstrates that it contains a single Raf protein kinase together with the molecular chaperones hsp90 and p50. The Raf-hsp90-p50 complex was observed in starved cells and in cells activated with serum or phorbol ester. Thus, changes in complex formation with hsp90 and p50 are not required for activation of the Raf protein kinase. However, Raf activation caused by Ras was associated with the translocation of the cytoplasmic Raf-hsp90-p50 complex to the cell membrane. Significantly, it is only the membrane-bound complex that exhibits increased protein kinase activity. Thus, the Ras-activated Raf protein kinase functions as a membrane-bound multi-subunit complex

Time matters – in vitro cellular disposition kinetics help rationalizing cellular potency disconnects

Loss in potency is commonly observed in early drug discovery when moving from biochemical to more complex cellular systems. Among other factors, low permeability is often considered to cause such potency disconnects. We developed a novel cellular disposition assay in MDCK cells to determine passive uptake clearance (PSinf), cell-to-medium ratios at steady-state (Kp) and the time to reach 90% steady-state (TTSS90) from a single experiment in a high-throughput format. The assay was validated using 40 marketed drugs, showing a wide distribution of PSinf and Kp values. The parameters generally correlated with transcellular permeability and lipophilicity, while PSinf data revealed better resolution in the high and low permeability ranges compared to traditional permeability data. A linear relationship between the Kp/PSinf ratio and TTSS90 was mathematically derived and experimentally validated, demonstrating the dependency of TTSS90 on the rate and extent of cellular accumulation. Cellular disposition parameters could explain potency (IC50) disconnects noted for seven Bruton’s tyrosine kinase degrader compounds in a cellular potency assay. In contrast to transcellular permeability, PSinf data enabled identification of the compounds with IC50 disconnects based on their time to reach equilibrium. Overall, the novel assay offers the possibility to address potency disconnects in early drug discovery

Psychosocial impact of living-related kidney transplantation on donors and partners

Living-related kidney transplantation (LRKT) is an option for children with end-stage renal failure. In addition to medical concerns, there is uncertainty about the psychological impact of living-related donation on parent donors and families. A survey was conducted on the decision making process and medical and psychosocial consequences of LRKT. Between 1992 and 1999, 20 parents donated a kidney for their child. A questionnaire including 24 items was sent to parent donors and their partners. Nineteen parents and partners responded; the median time after LRKT was 3years. Donors and partners reported an independent decision making process with no significant influence of partners, relatives, or hospital staff. Partners were more concerned about medical problems than donors themselves (P <0.02). Donors and partners cited no medical problems except sustained pain. Both reported an improved personal relationship towards the transplanted child. Donors and partners also cited an improved personal relationship. The vast majority (18/19) of couples still supported the decision for organ donation. In conclusion, there was a high degree of satisfaction with the decision making process in LRKT. The great majority of donors and partners did not report negative medical or psychological consequences. The relationship between donor, partner, and recipient child improved after LRK

Total synthesis of hypermodified epothilone analogs with potent in vitro antitumor activity

The convergent total synthesis of hypermodified epothilone analogs 1 and 2 has been achieved with the stereoselective cyclopropanation of allylic alcohol 17 and ring-closing olefin metathesis with diene 22 as the key steps. In spite of significant structural differences between these analogs and the natural epothilone scaffold, 1 and 2 are potent inducers of tubulin polymerization and inhibit the growth of human cancer cells in vitro with sub-nM IC50 values