Mechanisms of expression of apoptotic protease activating factor-1 (Apaf-1) in nuclear, mitochondrial and cytosolic fractions of the cerebral cortex of newborn piglets

The effects of statin therapy on brain tumors, particularly glioma: a review

Brain tumors account for less than 2% of all malignancies. However, they are associated with the highest morbidity and mortality rates among all solid tumors. The most common malignant primary brain tumors are glioma or glioblastoma (GBM), which have a median survival time of about 14 months, often suffer from recurrence after a few months following treatment, and pose a therapeutic challenge. Despite recent therapeutic advances, the prognosis for glioma patients is poor when treated with modern therapies, including chemotherapy, surgery, radiation, or a combination of these. Therefore, discovering a new target to treat brain tumors, particularly glioma, might be advantageous in raising progression-free survival and overall survival (OS) rates. Statins, also known as competitive HMG-CoA reductase inhibitors, are effective medications for reducing cholesterol and cardiovascular risk. The use of statins prior to and during other cancer treatments appears to enhance patient outcomes according to preclinical studies. After surgical resection followed by concurrent radiation and treatment, OS for patients with GBM is only about a year. Statins have recently emerged as potential adjuvant medications for treating GBM due to their ability to inhibit cell growth, survival, migration, metastasis, inflammation, angiogenesis, and increase apoptosis in-vitro and in-vivo studies. Whether statins enhance clinical outcomes, such as patient survival in GBM, is still debatable. This study aimed to explore the effects of statin therapy in the context of cancer treatment, with a particular focus on GBM.

Systematic validation and assessment of immunohistochemical markers for central nervous system pathology in cetaceans, with emphasis on auditory pathways

Cetacean neuropathology is a developing field that aims to assess structural and neurochemical changes involved in neurodegenerative, infectious and traumatic processes, however markers used previously in cetaceans have rarely undergone systematic validation. This is a prerequisite to investigating the potential damage inflicted on the cetacean auditory system by anthropogenic noise. In order to assess apoptotic, neuroinflammatory and structural aberrations on a protein level, the baseline expression of biomarker proteins has to be characterized, implementing a systematic approach to validate the use of anti-human and anti-laboratory animal antibodies in dolphin tissues. This approach was taken to study 12 different antibodies associated with hypoxic-ischemic, inflammatory, plastic and excitatory-inhibitory changes implicated in acoustic trauma within the ventral cochlear nuclei and inferior colliculi of 20 bottlenose dolphins (Tursiops truncatus). Out of the 12 tested antibodies, pro-apoptotic protease factor 1 (Apaf-1), diacylglycerolkinase-ζ (DGK-ζ), B-cell lymphoma related protein 2 (Bcl-2), amyloid-β peptide (Aβ) and neurofilament 200 (NF200) were validated employing Western blot analyses and immunohistochemistry (IHC). The results of the validation process indicate specific patterns of immunoreactivity that are comparable to those reported in other mammals, thus suggesting a key panel of IHC biomarkers of pathological processes in the cetacean brain. As a consequence, the antibodies tested in this study may constitute a valid tool for supporting existing diagnostic methods in neurological diseases. The approach of systematic validation of IHC markers in cetaceans is proposed as a standard practice, in order for results to be transparent, reliable and comparable.

The transcription factor c-Myc suppresses MiR-23b and MiR-27b transcription during fetal distress and increases the sensitivity of neurons to hypoxia-induced apoptosis

Previous studies reported that the expression of miR-23b-27b cluster was downregulated in embryonic brain cortices during hypoxia-induced neuronal apoptosis. However, the mechanism underlying this downregulation is not completely understood. Here, we report that the transcription factor c-Myc plays an important role in regulating the expression of miR-23b-27b cluster during hypoxia. First, the c-Myc protein level was significantly elevated in embryonic brain cortices in a mouse model of fetal distress. Second, forced overexpression or knockdown of c-Myc could suppress or increase the expression of miR-23b-27b cluster polynucleotides. Third, we identified 2 conserved c-Myc binding sites (E-boxes) in the enhancer and promoter regions of miR-23b-27b cluster in the mouse genome. Finally, we showed that elevated c-Myc expression led to an increase in the Apaf-1 level by suppressing miR-23b-27b cluster expression and that this enhanced neuronal sensitivity to apoptosis. In summary, our study demonstrates that c-Myc may suppress the expression of the miR-23b-27b cluster, resulting in additional neuronal apoptosis during hypoxia.

Altered mitochondria morphology and cell metabolism in Apaf1-deficient cells

Background

Apaf1 (apoptotic protease activating factor 1) is the central component of the apoptosome, a multiprotein complex that activates procaspase-9 after cytochrome c release from the mitochondria in the intrinsic pathway of apoptosis. Other cellular roles, including a pro-survival role, have also been described for Apaf1, while the relative contribution of each function to cell death, but also to cell homeostatic conditions, remain to be clarified.

Methodology and Principal Findings

Here we examined the response to apoptosis induction of available embryonic fibroblasts from Apaf1 knockout mice (MEFS KO Apaf1). In the absence of Apaf1, cells showed mitochondria with an altered morphology that affects cytochrome c release and basal metabolic status.

Conclusions

We analysed mitochondrial features and cell death response to etoposide and ABT-737 in two different Apaf1-deficient MEFS, which differ in the immortalisation protocol. Unexpectedly, MEFS KO Apaf1 immortalised with the SV40 antigen (SV40IM-MEFS Apaf1) and those which spontaneously immortalised (SIM-MEFS Apaf1) respond differently to apoptotic stimuli, but both presented relevant differences at the mitochondria when compared to MEFS WT, indicating a role for Apaf1 at the mitochondria.

s-Ethyl cysteine and s-propyl cysteine alleviate beta-amyloid induced cytotoxicity in nerve growth factor differentiated PC12 cells

Beta-amyloid peptide (Abeta) was used to induce cytotoxicity in nerve growth factor differentiated PC12 cells, and the effects of s-ethyl cysteine (SEC) and s-propyl cysteine (SPC) on anti-inflammatory protection, DNA fragmentation, mitochondrial membrane potential (MMP), and activity of Na(+)-K(+)-ATPase and caspases were examined. Abeta treatment significantly decreased cell viability and MMP, and increased lactate dehydrogenase (LDH) activity and DNA fragmentation (P < 0.05). The pretreatments from SEC or SPC at 2.5, 5, and 10 microM significantly enhanced cell viability and MMP, and lowered LDH activity and DNA fragmentation (P < 0.05). Abeta treatment also significantly decreased Na(+)-K(+)-ATPase activity and enhanced the activity of caspase-3 and caspase-8 (P < 0.05); however, the pretreatments from SEC or SPC significantly attenuated Abeta-induced reduction in Na(+)-K(+)-ATPase activity and elevation in caspase-3 and caspase-8 activities (P < 0.05). Abeta treatment increased the protein production and mRNA expression of interleukin (IL)-1beta, IL-6, and tumor necrosis factor-alpha (P < 0.05). The pretreatments from SEC at 10 microM or SPC at 2.5, 5, and 10 microM significantly suppressed mRNA expression and decreased the protein production of these cytokines. These results suggested that SEC and SPC were potent neuroprotective agents against Alzheimer's disease.

Severe hepatocellular injury with apoptosis induced by a hepatitis C polymerase inhibitor

GOALS

To describe the mechanisms of severe hepatocellular injury with apoptosis in 2 patients receiving hepatitis C virus (HCV)-796.

BACKGROUND

HCV-796 is a hepatitis C polymerase inhibitor approved by the US Food and Drug Administration for a phase 2 study of the treatment of hepatitis C in combination with PEG-Interferon and ribavirin.

RESULTS

The injury occurred after more than 12 weeks of treatment, with a >20-fold increase in serum alanine aminotransferase and aspartate aminotransferase, and a marked increase in total (and direct) bilirubin in the absence of cholestasis. There was no evidence of autoimmune or viral hepatitis. Involvement of the mitochondrial apoptotic pathway was demonstrated by (1) release of cytochrome C into the cytosol; (2) association of cytochrome C with apoptotic protease activating factor-1 in the cytosol; (3) activation of initiator caspase 9; (4) activation of effector caspase 3; (5) increased serum caspase-3 cleaved cytokeratin-18 peptide; (6) nuclear fragmentation; (7) mitochondrial structural abnormalities; (8) expression of light chain 3 B, an indicator of autophagy; (9) probable autophagy of mitochondria by autophagosomes; and (10) probable phagocytosis of apoptotic hepatocytes by activated macrophages. Immunoglobulin G immune complexes were identified in the hepatocytes and localized to the endoplasmic reticulum and Golgi of these patients after the drug-induced liver disease, reflecting a primary or secondary target. Hepatitis C treatment was discontinued at weeks 15 and 19 in patients 1 and 2, respectively. After more than 6 months off the medication, both patients normalized the serum alanine aminotransferase, aspartate aminotransferase, and total bilirubin with undetectable HCV RNA.

CONCLUSIONS

HCV-796 may cause severe hepatocellular injury and apoptosis, with a marked immune reaction in susceptible patients.

Expression of Apaf-1 and Caspase 9 gene in colorectal cancer and its significance

AIM: To investigate the significance of Apaf-1 and Caspase 9 expression in the carcinoma of large intestine.

METHODS: Real-time quantitative reverse transcription polymerase chain reaction (RQ-RT-PCR) technique was established for detecting Apaf-1 and Caspase 9 mRNA expression in tissues incised from 60 colorectal cancer patients examined by colonoscopy in the third hospital of Wuhan City.

RESULTS: Apaf-1 and Caspase 9 mRNA expression were significantly lower in colorectal cancer tissues than those in the normal tissues (0.561 ± 0.049 vs 0.947 ± 0.077, P < 0.01; 0.412 ± 0.014 vs 0.922 ± 0.062, P < 0.01). The expression levels of Apaf-1 and Caspase 9 mRNA had no marked differences between the normal tissues and cancer-adjacent tissues.

CONCLUSION: Apaf-1 and Caspase 9 gene dysfunction maybe contribute to the development and progression of colorectal cancer.

Novel sugar-cholestanols as anticancer agents against peritoneal dissemination of tumor cells

Chemically synthesized sugar-cholestanols with mono-, di-, and tri-saccharides attached to cholestanol showed strong inhibiting activity against the proliferation of colorectal and gastric cancer cells. In contrast, cholestanol without sugar moieties was totally ineffective. Furthermore, when cancer cells were exposed to GlcNAcRbetacholestanol (R=(-) or beta1-3Gal), the compound was rapidly taken up via the lipid rafts/microdomains on the cell surface. The uptake of sugar-cholestanol in mitochondria increased gradually and was followed by the release of cytochrome c from mitochondria and the activation of apoptotic signals through the mitochondrial pathway and the caspase cascade, leading to apoptotic cell death, characterized by DNA ladder formation and nuclear fragmentation. Additionally, the examination of GlcNAcRbetacholestanol in a mouse model of peritoneal dissemination showed a dramatic reduction of tumor growth (P < 0.003) and prolonged mouse survival time (P<0.0001). Based on these observations, we believe that the sugar-cholestanols described here have clinical potential as novel anticancer agents.