A mini-review on anticancer-related properties of azithromycin and its potential activities in overcoming the challenges of glioblastoma.

The resistance, plasticity and heterogeneity of cancer cells, including glioblastoma (GB) cells, have prompted the investigation of various agents for possible adjuncts and alternatives to existing therapies. This includes a macrolide antibiotic, azithromycin (AZI). It possesses intriguing anticancer properties in a range of cancer models in vitro, such as antiproliferative, pro-apoptotic, anti-autophagy and anti-angiogenic effects. In fact, AZI is renowned for its ability to eradicate cancer stem cells by inhibiting mitochondrial biogenesis and respiration. AZI-containing regimens in cancer patients for different purposes have shown favourable (i.e., attributed to its antibacterial activity) and unfavourable outcomes. Whilst its direct anticancer effects have yet to be clinically proven. To that end, this review provides a summary of AZI anticancer studies and delineates its potential activities in overcoming the challenges of GB.

Characterisation of Primary Human Hippocampal Astrocyte Cell Culture Following Exposure to Hypoxia.

Background: The present study aimed to understand the characterisation of human hippocampal astrocyte following hypoxia exposure. Based on the preliminary screening, 15 min was chosen as the time point and the cells were exposed to different oxygen percentages. Methods: The Trypan blue viability assay used to examine cell death. Immunofluorescence assay, glial fibrillary acidic protein (GFAP) was used to portray the morphology of astrocytes. The hypoxia-inducible factor 1 (HIF-1) staining was performed to confirm hypoxia induced cell death and there was a dramatic expression of HIF-1α displayed in exposed astrocyte cells compared to the control. In molecular level, genes were chosen, such as glyceraldehyde 3-phosphate dehydrogenase (GAPDH), GFAP, HIF-1α and B-cell lymphoma 2 (Bcl-2) and ran the reverse transcription-polymerase chain reaction (RT-PCR). Results: Microscope revealed a filamentous and clear nucleus appearance in a control whereas the rupture nuclei with no rigid structure of the cell were found in the 3% oxygen. The control and hypoxia cells were also stained with the annexin V-fluorescein isothiocyanate (annexin V-FITC). Fluorescence microscope reveals astrocyte cells after hypoxia showed higher expression of nuclei but not in control. Merging PI and FITC showed the differences of nuclei expression between the control and hypoxia. In the molecular analysis, there were significant changes of GFAP, HIF-1α and Bcl-2 in hypoxia exposed cells when compared to the control group. Conclusion: Cells that were exposed to hypoxia (3% oxygen for 15 min) clearly showed damage. General view of human hippocampal astrocyte genomic response to hypoxia was obtained.

Insights regarding mitochondrial DNA copy number alterations in human cancer (Review).

Mitochondria are the critical organelles involved in various cellular functions. Mitochondrial biogenesis is activated by multiple cellular mechanisms which require a synchronous regulation between mitochondrial DNA (mtDNA) and nuclear DNA (nDNA). The mitochondrial DNA copy number (mtDNA­CN) is a proxy indicator for mitochondrial activity, and its alteration reflects mitochondrial biogenesis and function. Despite the precise mechanisms that modulate the amount and composition of mtDNA, which have not been fully elucidated, mtDNA­CN is known to influence numerous cellular pathways that are associated with cancer and as well as multiple other diseases. In addition, the utility of current technology in measuring mtDNA­CN contributes to its extensive assessment of diverse traits and tumorigenesis. The present review provides an overview of mtDNA­CN variations across human cancers and an extensive summary of the existing knowledge on the regulation and machinery of mtDNA­CN. The current information on the advanced methods used for mtDNA­CN assessment is also presented.

Exploring the cytotoxicity and anticancer effects of doxycycline and azithromycin on human glioblastoma multiforme cells.

BACKGROUND: Previous studies had reported on the cytotoxic activities of generic antibiotics such as doxycycline (DOXY) and azithromycin (AZI) in multiple types of human cancers. Given that resistance to standard anti-glioblastoma multiforme (GBM) drug [temozolomide (TMZ)] is common and inevitable, alternative candidates are greatly needed. PURPOSE AND METHOD: The present study was undertaken to explore the cytotoxicity and anticancer effects of DOXY and AZI on human GBM U87 cells via 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT), Hoechst, Annexin V-FITC/PI, and clonogenic assays. CompuSyn software was used to determine the combination index (CI) for DOXY+AZI. RESULT: Individual treatment with DOXY and AZI decreased U87 cell viability in dose- and time-dependent, and quantitatively comparable to TMZ. Nevertheless, combinations of both antibiotics evidenced antagonistic behaviour in U87 cells. Increased apoptotic event was also observed with the individual treatment of DOXY and AZI. Furthermore, the proliferative and clonogenic capability of 21-day survived U87 cells was completely terminated by DOXY and AZI, but not TMZ. CONCLUSION: The antiproliferative and apoptosis-inducing activity exhibited by both antibiotics against U87 cells demonstrates their potential as a likely alternative to combat GBM. It would be interesting to find out more about their molecular players and cytotoxic effects in different types of GBM cells, including glioma stem cells (GSCs).

Lentivirus vector­mediated genetic manipulation of oncogenic pathways induces tumor formation in rabbit brain.

Translation of promising experimental therapies from rodent models to clinical success has been complicated as the novel therapies often fail in clinical trials. Existing rodent glioma models generally do not allow for preclinical evaluation of the efficiency of novel therapies in combination with surgical resection. Therefore, the aim of the present study was to develop a larger animal model utilizing lentivirus vector­mediated oncogenic transformation in the rabbit brain. Lentiviruses carrying constitutively active AKT and H­Ras oncogenes, and p53 small interfering (si)RNA were introduced into newborn rabbit neural stem cells (NSCs) and intracranially implanted into rabbits' brains to initiate tumor formation. In one of the ten rabbits a tumor was detected 48 days after the implantation of transduced NSCs. Histological features of the tumor mimic was similar to a benign Grade II ganglioglioma. Immunostaining demonstrated that the tissues were positive for AKT and H­Ras. Strong expression of GFAP and Ki­67 was also detected. Additionally, p53 expression was notably lower in the tumor area. The implantation of AKT, H­Ras and p53 siRNA transduced NSCs for tumor induction resulted in ganglioglioma formation. Despite the low frequency of tumor formation, this preliminary data provided a proof of principle that lentivirus vectors carrying oncogenes can be used for the generation of brain tumors in rabbits. Moreover, these results offer noteworthy insights into the pathogenesis of a rare brain tumor, ganglioglioma.

Accumulation of Mitochondrial DNA Microsatellite Instability in Malaysian Patients with Primary Central Nervous System Tumors.

AIM: To determine the mitochondrial microsatellite instability (mtMSI) status in a series of Malaysian patients with brain tumors. Furthermore, we analyzed whether the mtMSI status is associated with the clinicopathological features of the patients. MATERIAL AND METHODS: Forty fresh frozen tumor tissues along with blood samples of brain tumor patients were analyzed for mtMSI by PCR amplification of genomic DNAs, and the amplicons were directly sequenced in both directions using Sanger sequencing. RESULTS: Microsatellite analysis revealed that 20% (8 out of 40) of the tumors were mtMSI positive with a total of 8 mtMSI changes. All mtMSI markers were detected in D310 and D16184 of the D-loop region. Additionally, no significant association was observed between mtMSI status and clinicopathological features. CONCLUSION: The variations, specifically the mtMSI, suggest that the mitochondrial DNA (mtDNA) can be targeted for genomic alteration in brain tumors. Therefore, the specific role of mtDNA alteration in brain tumor development and prognosis requires further investigation.

Anti-Cancer Properties of Heterotrigona itama sp. Honey Via Induction of Apoptosis in Malignant Glioma Cells.

BACKGROUND: There has been increasing evidence showing that stingless bee honey exhibits anti-oxidant, anti-inflammatory and anti-cancer properties. Pharmacologically-active components in honey such as flavonoids and phenolic constituents are known to contribute to its medicinal benefits. To the best of our knowledge, this is the first study on evaluating anti-cancer effects of locally-produced Malaysian stingless bee honey from Heterotrigona itama sp. on malignant glioma cells. METHODS: Proliferation and apoptosis studies of U-87 MG cells following stingless bee honey treatment were carried out using MTS assay and acridine orange/propidium iodide dual staining, respectively. RESULTS: Results demonstrated time and dose-dependent cytotoxicity using 0.625%, 1.25% and 10% stingless bee honey (P < 0.05). IC50 values were calculated using cells treated with 10% stingless bee honey. It was also observed that 10% stingless bee honey induced nuclear shrinkage, chromatin condensation and nucleus fragmentation, indicating that cellular changes were consistent with the apoptotic characteristics of the cells. CONCLUSION: These data provide a good basis for further evaluation of the medicinal properties of stingless bee honey from Heterotrigona itama sp. This source of honey may serve as a potential therapy for malignant glioma.

Roles of EphA2 Receptor in Angiogenesis Signaling Pathway of Glioblastoma Multiforme.

Glioblastoma multiforme (GBM) is one of the most common primary brain tumours in adults, accounting for almost 65% of all cases. Among solid tumours, GBM is characterised by strong angiogenesis, including the highest degree of vascular proliferation and endothelial cell hyperplasia. Despite numerous improvements in existing treatment approaches, the prognosis of GBM patients remains poor, with a mean survival of only 14.6 months. Growing evidence has shown significant overexpression of the ephrin type-A receptor 2 (EphA2) receptor in various malignancies, including GBM, as well as a correlation to poor prognoses. It is believed that EphA2 receptors play important roles in mediating GBM tumourigenesis, including invasion, metastasis, and angiogenesis. Despite the clinical and pathological importance of tumour-associated vasculature, the underlying mechanism involving EphA2 is poorly known. Here, we have summarised the current knowledge in the field regarding EphA2 receptors' roles in the angiogenesis of GBM.

Mouse model of intracerebellar haemorrhage.

The present study aimed to investigate the behavior and neuronal morphological changes in the perihaemorrhagic tissue of the mouse intracerebellar haemorrhage experimental model. Adult male Swiss albino mice were stereotactically infused with collagenase type VII (0.4U/µl of saline) unilaterally in to the cerebellum, following anaesthesia. Motor deficits were assessed using open field and composite score for evaluating the mouse model of cerebellar ataxia at 1, 3, 7, 14 and 21 days after collagenase infusion. The animals were sacrificed at the same time interval for evaluation of perihaematomal neuronal degeneration using haematoxylin and eosin staining and Annexin V-FITC/Propidium iodide assay. At the end of the study, it was found that infusion of 0.4U collagenase produces significant locomotor and ataxic deficit in the mice especially within the first week post surgery, and that this gradually improved within three weeks. Neuronal degeneration evident by cytoplasmic shrinkage and nuclear pyknosis was observed at the perihaematomal area after one day; especially at 3 and 7 days post haemorrhage. By 21 days, both the haematoma and degenerating neurons in the perihaematomal area were phagocytosed and the remaining neuronal cells around the scar tissue appeared normal. Moreover, Annexin-V/propidium iodide-positive cells were observed at the perihaematomal area at 3 and 7 days implying that the neurons likely die via apoptosis. It was concluded that a population of potentially salvageable neurons exist in the perihaematomal area after cerebellar haemorrhage throughout a wide time window that could be amenable to treatment.

15-Lipoxygenase-1 induces lipid peroxidation and apoptosis, and improves survival in rat malignant glioma.

BACKGROUND: Previous studies suggest either an anti- or pro-apoptotic role for 15-lipoxygenase-1 in carcinogenesis. MATERIALS AND METHODS: We used adenovirus gene transfer of human 15-lipoxygenase-1 to characterize its effects in vitro and in vivo. RESULTS: 15-Lipoxygenase-1 expression in mouse macrophages resulted in a significant, 25-fold, induction in the production of the specific 15-lipoxygenase-1 product 13-hydroxyoctadecadienoic acid. Tail vein gene transfers in mice led to highest expression of the transduced 15-lipoxygenase-1 in liver and spleen. In the liver, 15-lipoxygenase-1 significantly increased lipid peroxidation by 3.5-fold and 2-fold, three and seven days after transduction, respectively. A significant 32-fold induction in caspase-3 activity was detected in 15-lipoxygenase-1 expressing livers seven days after transduction. In a syngeneic rat model of malignant glioma, 15-lipoxygenase-1 extended survival significantly (p=0.001). CONCLUSION: Our results support the pro-apoptotic role of 15-lipoxygenase-1 and suggest that 15-lipoxygenase-1 could be a potential new target gene for the therapy of malignant glioma.

Molecular genetic analysis of a suprasellar immature teratoma : mutation of exon 4 p53 gene.

We described an intracranial immature teratoma in a 13 year old Malay boy who presented with history of chronic headache and blurring of vision. Physical findings revealed bilateral papilloedema but no other localizing sign. A Magnetic Resonance Imaging of the brain revealed a suprasellar well defined lobulated midline heterogenous mass which was intraoperatively described as mainly solid tumour with multiple small cystic component filled with yellowish jelly like material. Histopathological finding confirmed the case as immature teratoma. Molecular genetic analysis of p53 and p27 genes revealed substitution of nucleotide G to C at location nucleotide 12139, exon 4 of gene p53. No alteration was detected at exon 5-6 and 8 of p53 gene and exon 1 and 2 of p27 gene. This is the first case report of an intracranial immature teratoma with genetic mutation occuring in a Malay boy.

Molecular genetic analysis of BAX and cyclin D1 genes in patients with malignant glioma.

INTRODUCTION AND OBJECTIVES: Brain tumorigenesis is a complex process involving multiple genetic alterations. Cyclin D1 and BAX genes are two of the most important regulators in controlling the normal proliferation and apoptosis of cells, respectively. In this study, we analysed the possibilities of involvement of cyclin D1 and BAX genes in the gliomagenesis. METHODS AND RESULTS: In determining gene alterations of exon 4 of cyclin D1 gene and exon 6 of BAX gene, all samples were amplified by polymerase chain reaction (PCR) and subsequently by direct sequencing. Our results showed a frameshift mutation (G base deletion) at nucleotide 82 of codon 28 in exon 4 of the cyclin D1 gene and another frameshift mutation with a deletion of C base at nucleotide 153 of exon 6 of the BAX gene in two separate cases of a glioblastoma multiform (WHO Grade IV) sample. CONCLUSION: These findings suggest that both cyclin D1 and BAX genes alteration are rarely found in brain tumors. However, the alteration might cause a significant effect of the normal protein production and this might contribute to the development of brain tumorigenesis in Malaysian patients.