Thinking within the D box: initial identification of Cdh1-APC substrates in the nervous system

The anaphase-promoting complex (APC) has a well-established role in cell cycle control, but recent exciting evidence has uncovered unexpected neurobiological functions for this complex E3 ubiquitin ligase. With its co-activator Cdh1, APC's effects upon the nervous system range from regulation of axon growth and patterning to development of synapses to neuronal survival. The Cdh1-APC substrates that control these biological processes in neurons are just beginning to be identified. These findings may offer a glimpse of the wide spectrum of neural activities that are orchestrated by Cdh1-APC.     

Regulation of autophagy by reactive oxygen species (ROS): implications for cancer progression and treatment

Reactive oxygen species (ROS) have been identified as signaling molecules in various pathways regulating both cell survival and cell death. Autophagy, a self-digestion process that degrades intracellular structures in response to stress, such as nutrient starvation, is also involved in both cell survival and cell death. Alterations in both ROS and autophagy regulation contribute to cancer initiation and progression, and both are targets for developing therapies to induce cell death selectively in cancer cells. Many stimuli that induce ROS generation also induce autophagy, including nutrient starvation, mitochondrial toxins, hypoxia, and oxidative stress. Some of these stimuli are under clinical investigation as cancer treatments, such as 2-methoxyestrodial and arsenic trioxide. Recently, it was demonstrated that ROS can induce autophagy through several distinct mechanisms involving Atg4, catalase, and the mitochondrial electron transport chain (mETC). This leads to both cell-survival and cell-death responses and could be selective toward cancer cells. In this review, we give an overview of the roles ROS and autophagy play in cell survival and cell death, and their importance to cancer. Furthermore, we describe how autophagy is mediated by ROS and the implications of this regulation to cancer treatments.     

Therapeutic action and underlying mechanisms of a combination of two pentacyclic triterpenes, α- and β-amyrin,in a mouse model of colitis

Background and purpose:

α- and β-amyrin are pentacyclic triterpenes found in plants and are known to exhibit pronounced anti-inflammatory effects. Here, we evaluated the effects of a 1:1 mixture of α- and β-amyrin (α,β-amyrin) on an experimental model of colitis in mice.

Experimental approach:

Colitis was induced in Swiss male mice by trinitrobenzene sulphonic acid (TNBS) and followed up to 72 h; animals were treated systemically with α,β-amyrin, dexamethasone or vehicle. Macro- and microscopic damage, myeloperoxidase activity and cytokine levels were assessed in colons. Histological sections were immunostained for cyclooxygenase-2 (COX-2), vascular endothelial growth factor, phospho-p65 nuclear factor-κB (NF-κB) and phospho-cyclic AMP response element-binding protein (CREB)

Key results:

TNBS-induced colitis was associated with tissue damage, neutrophil infiltration and time-dependent increase of inflammatory mediators. Treatment with α,β-amyrin (3 mg·kg⁻¹, i.p.) or dexamethasone (1 mg·kg⁻¹, s.c.) consistently improved tissue damage scores and abolished polymorphonuclear cell infiltration. α,β-Amyrin, like dexamethasone, significantly diminished interleukin (IL)-1β levels and partially restored IL-10 levels in colon tissues 72 h after colitis induction, but only α,β-amyrin reduced vascular endothelial growth factor expression by immunohistochemistry. The colonic expression of COX-2 at 24 h and that of phospho-NF-κB and phospho-CREB (peaking at 6 h) after colitis induction were consistently inhibited by both α,β-amyrin and dexamethasone.

Conclusions and implications:

Systemic administration of α,β-amyrin exerted a marked and rapid inhibition of TNBS-induced colitis, related to the local suppression of inflammatory cytokines and COX-2 levels, possibly via inhibition of NF-κB and CREB-signalling pathways. Taken together, our data suggest a potential use of α,β-amyrin to control inflammatory responses in bowel disease.     

Methylene blue dye--a safe and effective alternative for sentinel lymph node localization

Abstract:  Sentinel lymph node (SLN) biopsy has emerged as an effective diagnostic tool in axillary staging in breast cancer. The commonly used technique employs isosulfan blue/patent blue V combined with radioactive colloid tracer. Methylene blue (MB) is a less expensive and readily available alternative dye. The study evaluated the safety and efficacy of MB in SLN localization. A retrospective study of 329 patients with early breast cancer who had SLN localization as part of an ethically approved prospective evaluation study of SLN localization technique was carried out. Lymph node positive, tumors >2 cm on clinical and radiological evaluation, those with previous breast and axillary surgery, neo-adjuvant chemotherapy were excluded from the study. One hundred seventy three patients underwent SLN localization using 1 mL of 1% MB, and a combined MB-radio colloid tracer technique was used in the other 156 patients. Allocation to the groups was by simple randomization. Injection of the dye and radioisotope was into the subdermal plane in the sub-areolar region. Patients underwent breast conservation surgery or mastectomy with SLN directed four node axillary sampling ± axillary clearance. The lymph node was examined by standard microscopy. There were no reported complications with the use of MB aside from temporary tattooing. The technique failed in eight patients giving an identification rate of 97.6%. Ten of the 258 (3.9%) patients had false-negative SLN, with negative predictive value of 96.1%, sensitivity of predicting further axillary disease of 73%, specificity of 87.3%, and overall accuracy of 85.7%. Reported adverse reaction to isosulfan blue/patent blue V varied from minor to severe anaphylactic reactions (1–3%) requiring vigorous resuscitation. Subdermal sub-areolar injection of MB is safe and effective readily available dye for SLN localization in axillary staging of breast cancer with no major adverse reaction.