Progress from clinical trials and emerging non-conventional therapies for the treatment of Medulloblastomas

Inhibiting microcephaly genes as alternative to microtubule targeting agents to treat brain tumors

Medulloblastoma (MB) and gliomas are the most frequent high-grade brain tumors (HGBT) in children and adulthood, respectively. The general treatment for these tumors consists in surgery, followed by radiotherapy and chemotherapy. Despite the improvement in patient survival, these therapies are only partially effective, and many patients still die. In the last decades, microtubules have emerged as interesting molecular targets for HGBT, as various microtubule targeting agents (MTAs) have been developed and tested pre-clinically and clinically with encouraging results. Nevertheless, these treatments produce relevant side effects since they target microtubules in normal as well as in cancerous cells. A possible strategy to overcome this toxicity could be to target proteins that control microtubule dynamics but are required by HGBT cells much more than in normal cell types. The genes mutated in primary hereditary microcephaly (MCPH) are ubiquitously expressed in proliferating cells, but under normal conditions are selectively required during brain development, in neural progenitors. There is evidence that MB and glioma cells share molecular profiles with progenitors of cerebellar granules and of cortical radial glia cells, in which MCPH gene functions are fundamental. Moreover, several studies indicate that MCPH genes are required for HGBT expansion. Among the 25 known MCPH genes, we focus this review on KNL1, ASPM, CENPE, CITK and KIF14, which have been found to control microtubule stability during cell division. We summarize the current knowledge about the molecular basis of their interaction with microtubules. Moreover, we will discuss data that suggest these genes are promising candidates as HGBT-specific targets.

Induction of antigen-specific cytotoxic T-cell response by dendritic cells generated from ecto-mesenchymal stem cells infected with an adenovirus containing the MAGE-D4a gene

The present study aimed to investigate the feasibility of using ecto-mesenchymal stem cell (EMSC)-derived dendritic cells (DCs) for glioma immunotherapy following infection by a recombinant adenovirus containing the melanoma-associated antigen D4a (MAGE-D4a) gene. The ex vivo cultured EMSCs were infected by the adenoviral plasmid containing MAGE-D4a (pAd/MAGE-D4a). Efficiency of transfection was evaluated through the detection of green fluorescent protein-marked MAGE-D4a. The MAGE-EMSCs were induced to differentiate into DCs, termed as MAGE-EMSCs-DCs. The morphology was subsequently analyzed under a microscope, and methyl thiazolyl tetrazolium (MTT) and interferon-γ (IFN-γ) assays were performed to analyze the cytotoxicity of the MAGE-EMSC-DCs on the human glioma U251 cell line. Following purification by magnetic-activated cell sorting, the EMSCs grew into swirls, with a long spindle shape and were fibroblast-like. The gene transfected with recombinant adenovirus vectors maintained high and stable expression levels of MAGE-D4a, and its efficiency was increased in a multiplicity of infection-dependent manner. The results of the MTT assay indicated that the T cells, primed by the recombinant MAGE-D4a-infected EMSC-DCs in vitro, recognized MAGE-D4a-expressing tumor cell lines in a human leukocyte antigen class I-restricted manner, and evoked a higher cytotoxic T cell (CTL) response. The CTL response induced by the MAGE-EMSC-DCs, co-cultured with the U251 cells for 24 h, produced 765.0 pg/ml IFN-γ, which was significantly greater when compared to the control wells. T lymphocytes stimulated by MAGE-EMSC-DCs evoke a higher CTL response to human glioma cell lines, and may serve as a promising therapeutic modality for the treatment of MAGE-D4a-expressing glioma.

Novel agents for advanced pancreatic cancer

Pancreatic cancer is relatively insensitive to conventional chemotherapy. Therefore, novel agents targeting dysregulated pathways (MAPK/ERK, EGFR, TGF-β, HEDGEHOG, NOTCH, IGF, PARP, PI3K/AKT, RAS, and Src) are being explored in clinical trials as monotherapy or in combination with cytotoxic chemotherapy. This review summarizes the most recent advances with the targeted therapies in the treatment of patients with advanced pancreatic cancer.

Autophagy contributes to ING4-induced glioma cell death

Previous studies suggest that ING4, a novel member of ING (inhibitor of growth) family, can inhibit brain tumor growth. However, whether autophagy is involved in ING4-induced cell death still remains unknown. In this study, we found that in addition to apoptosis, autophagy also contributed to cell death induced by ING4. Autophagy levels were elevated following the exposure to Ad-ING4, including enhanced fluorescence intensity of monodansylcadervarine (MDC), a specific in vivo marker for autophagic vacuoles, and increased expression levels of the LC3-II and Beclin-1, wheras the autophagic levels were attenuated following the pretreatment of 3-MA, the inhibitor of autophagy, which significantly decreased the Ad-ING4-induced cell death compared with caspase inhibitor zVAD. Furthermore, ING4 also induced mitochondrial dysfunction, such as mitophagy, collapse of mitochondrial membrane potential and the intracellular ROS, which indicated that mitochondria might be associated with the process of autophagic cell death of glioma cells. Finally, the relationship among Bax, Bcl-2, Beclin-1 and caspase family proteins levels were analyzed in glioma cells U251MG and LN229 infected with Ad-ING4 or Ad-lacZ. It is suggested that both autophagy and apoptosis could contribute to ING4-induced glioma cell death, and mitochondria might play an important role in this process. Our findings reveal novel aspects of the autophagy in glioma cells that underlie the cytotoxic action of ING4, possibly providing new insights in the development of combinatorial therapies for gliomas.