Apoptosis incidence and protein expression of p53, TGF-beta receptor II, p27Kip1, and Smad4 in benign, premalignant, and malignant human prostate

Deregulation of apoptosis is involved in prostate cancer development and progression. This study involved an immunohistochemical "profiling" of prostate tissue specimens from patients who underwent prostatectomy for localized prostate cancer, to identify apoptosis-specific alterations associated with premalignant precursor lesions. Prostate tissue was pathologically evaluated, and areas of benign acini, high-grade prostate intraepithelial neoplasia (HGPIN), and prostate cancer were identified. Immunohistochemical analysis was performed to determine the expression of p27Kip1, a key cell cycle regulator, transforming growth factor (TGF)-beta receptor II (TbetaRII), a critical signaling effector of TGF-beta; Smad4, a downstream intracellular effector of TGF-beta signaling; p53, a key apoptosis regulator; and prostate-specific antigen (PSA), a clinical marker of prostate cancer. The apoptotic index of the same cell populations was determined using the transferase-mediated digoxigenin-tagged 16-desoxy-uridine-triphosphate nick end labeling assay. Our findings indicate a significant reduction in p27Kip1 immunoreactivity in HGPIN (P<0.0001) and prostate cancer (P<0.0001) compared with the benign tissue. A significant down-regulation was detected in TbetaRII expression in HGPIN and prostate cancer compared with benign prostatic hyperplasia (BPH)(P<0.001). A significant decrease was also observed in Smad4 levels in HGPIN and prostate cancer compared with BPH (P<0.001). Evaluation of the incidence of apoptosis revealed a significant decrease in the apoptotic index among the epithelial cell populations in HGPIN and a further decrease in prostate carcinoma (P<0.01). This reduced apoptotic index correlated with a significant increase in p53 immunoreactivity in the prostatic carcinoma foci. Prostate cancer cells exhibited strong nuclear staining for p53 compared with adjacent HGPIN (P<0.05) and the benign lesions of the same prostate specimens (P<0.05). A significant reduction in PSA immunostaining was detected in HGPIN and prostate carcinoma foci compared with the benign glandular epithelia (P<0.001). These results further define deregulation of TGF-beta signaling effectors as a molecular basis for loss of apoptotic control contributing to the development of prostate tumors. Identification of apoptotic regulators in precursor premalignant lesions may have prognostic significance in disease progression as well as therapeutic value for targeting prostate cancer.     

Guanine nucleotide exchange factors of the cytohesin family and their roles in signal transduction

Summary:  Members of the cytohesin protein family, a group of guanine nucleotide exchange factors for adenosine diphosphate ribosylation factor (ARF) guanosine triphosphatases, have recently emerged as important regulators of signal transduction in vertebrate and invertebrate biology. These proteins share a modular domain structure, comprising carboxy-terminal membrane recruitment elements, a Sec7 homology effector domain, and an amino-terminal coiled-coil domain that serve as a platform for their integration into larger signaling complexes. Although these proteins have a highly similar overall build, their individual biological functions appear to be at least partly specific. Cytohesin-1 had been identified as a regulator of β2 integrin inside-out regulation in immune cells and was subsequently shown to be involved in mitogen-associated protein kinase signaling in tumor cell proliferation as well as in T-helper cell activation and differentiation. Cytohesin-3, which had been discovered to be strongly associated with T-cell anergy, was very recently described as an essential component of insulin signal transduction in Drosophila and in human and murine liver cells. Future work will aim to dissect the mechanistic details of the modes of action of the cytohesins as well as to define the precise roles of these versatile proteins in vertebrates at the genetic level.     

Activated Ras/JNK driven Dilp8 in imaginal discs adversely affects organismal homeostasis during early pupal stage in Drosophila,a new checkpoint for development

Background

Dilp8-mediated inhibition of ecdysone synthesis and pupation in holometabolous insects maintains developmental homeostasis through stringent control of timing and strength of molting signals. We examined reasons for normal pupation but early pupal death observed in certain cases.

Results

Overexpression of activated Ras in developing eye/wing discs inhibited Ptth expression in brain via upregulated JNK signaling mediated Dilp8 secretion from imaginal discs, which inhibited ecdysone synthesis in prothoracic gland after pupariation, leading to death of ~25- to 30-hour-old pupae. Inhibition of elevated Ras signaling completely rescued early pupal death while post-pupation administration of ecdysone to organisms with elevated Ras signaling in eye discs partially rescued their early pupal death. Unlike the earlier known Dilp8 action in delaying pupation, hyperactivated Ras mediated elevation of pJNK signaling in imaginal discs caused Dilp8 secretion after pupariation. Ectopic expression of certain other transgene causing pupal lethality similarly enhanced pJNK and early pupal Dilp8 levels. Suboptimal ecdysone levels after 8 hours of pupation prevented the early pupal metamorphic changes and caused organismal death.

Conclusions

Our results reveal early pupal stage as a novel Dilp8 mediated post-pupariation checkpoint and provide further evidence for interorgan signaling during development, wherein a peripheral tissue influences the CNS driven endocrine function.

     

The persistence of interleukin-6 is regulated by a blood buffer system derived from dendritic cells

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Mechanisms Involved in the Binding of Thymocytes to Rat Thymic Dendritic Cells

The effects of monoclonal antibodies (mAbs) to cell-surface molecules, divalent cations, and various cell-signaling and metabolic inhibitors on the binding of thymocytes to rat thymic dendritic cells (TDC) were studied using a rosette assay. It was found that TDC/thymocyte adhesion was stronger and faster at 37°C than at 4°C. Flow cytometric analysis demonstrated that bound thymocytes were predominantly CD4⁺CD8⁺ and CD4⁺CD8^-, but in comparison to the phenotype of whole thymocytes, they were enriched in the mature TCRαβ^hi subset. The binding of thymocytes to TDC at 37°C was almost completely dependent on Ca²⁺ and Mg²⁺ and partly on an intact cytoskeleton and calmodulin-dependent protein kinase. The adhesion was independent of new protein synthesis and the activities of protein kinases A and C, tyrosine kinases, as well as phosphotyrosine protein phosphatases. The TDC/thymocyte adhesion at 37°C was partly blocked by anti-LFA-1 (WT.1), anti-CD18 (WT.3), and anti-ICAM-1 (1A29) mAb. MAbs to class II MHC (OX-3 and OX-6), CD4 (W3/25), CD8 (OX-8), and αβTCR (R73) stimulated the adhesion via an LFA-1-dependent pathway, whereas an anti-CD45 mAb (G3C5) stimulated the rosette formation independently of LFA-1. MAbs to CD2 (OX-34), CD11b (ED7), CD11b/c (OX-42), and class I MHC (OX-18) were without significant effects on the adhesion process.     

Ras homolog gene family H (RhoH) deficiency induces psoriasis-like chronic dermatitis by promoting TH17 cell polarization

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Physiological mechanisms of TRPC activation

TRPC (canonical transient receptor potential) channels are vertebrate homologs of the Drosophila photoreceptor channel, TRP. Considerable research has been brought to bear on the seven members of this family, especially with regard to their possible role in calcium entry. Unfortunately, the current literature presents a confusing picture, with different laboratories producing widely differing results and interpretations. It appears that ectopically expressed TRPC channels can be activated by phospholipase C products (generally, diacylglycerols), by stimulation of trafficking to the plasma membrane, or by depletion of intracellular Ca²⁺ stores. Here, I discuss the possibility that these diverse experimental findings arise because TRPC channels can, under both experimental as well as physiological conditions, be activated in three distinct ways, possibly depending on their subunit composition and/or signaling complex environment. The TRPCs may be unique among ion-channel subunit families in being able to participate in the assembly and function of multiple types of physiologically important ion channels.