The cerebral ischemia injury can result in neuronal death and/or functional impairment, which leads to further damage and dysfunction after recovery of blood supply. Cerebral ischemia/reperfusion injury (CIRI) often causes irreversible brain damage and neuronal injury and death, which involves many complex pathological processes including oxidative stress, amino acid toxicity, the release of endogenous substances, inflammation and apoptosis. Oxidative stress and inflammation are interactive and play critical roles in ischemia/reperfusion injury in the brain. Oxidative stress is important in the pathological process of ischemic stroke and is critical for the cascade development of ischemic injury. Oxidative stress is caused by reactive oxygen species (ROS) during cerebral ischemia and is more likely to lead to cell death and ultimately brain death after reperfusion. During reperfusion especially, superoxide anion free radicals, hydroxyl free radicals, and nitric oxide (NO) are produced, which can cause lipid peroxidation, inflammation and cell apoptosis. Inflammation alters the balance between pro-inflammatory and anti-inflammatory factors in cerebral ischemic injury. Inflammatory factors can therefore stimulate or exacerbate inflammation and aggravate ischemic injury. Neuroprotective therapies for various stages of the cerebral ischemia cascade response have received widespread attention. At present, neuroprotective drugs mainly include free radical scavengers, anti-inflammatory agents, and anti-apoptotic agents. However, the molecular mechanisms of the interaction between oxidative stress and inflammation, and their interplay with different types of programmed cell death in ischemia/reperfusion injury are unclear. The development of a suitable method for combination therapy has become a hot topic.

Tumor-specific translocations are common in tumors of mesenchymal origin. Whether the translocation determines the phenotype, or vice versa, is debatable. Ewing's family tumors (EFT) are consistently associated with an EWS-FLI1 translocation and a primitive neural phenotype. Histogenesis and classification are therefore uncertain. To test whether EWS-FLI1 fusion gene expression is responsible for the primitive neuroectodermal phenotype of EFT, we established a tetracycline-inducible EWS-FLI1 expression system in a rhabdomyosarcoma cell line RD. Cell morphology changed after EWS-FLI1 expression, resembling cultured EFT cells. Xenografts showed typical EFT features, distinct from tumors formed by parental RD. Neuron-specific microtubule gene MAPT, parasympathetic marker cholecystokinin, and epithelial marker keratin 18 were up-regulated. Conversely, myogenesis was diminished. Comparison of the up-regulated genes in RD-EF with the Ewing's signature genes identified important EWS-FLI1 downstream genes, many involved in neural crest differentiation. These results were validated by real-time reverse transcription-PCR analysis and RNA interference technology using small interfering RNA against EWS-FLI1 breakpoint. The present study shows that the neural phenotype of Ewing's tumors is attributable to the EWS-FLI1 expression and the resultant phenotype resembles developing neural crest. Such tumors have a limited neural phenotype regardless of tissue of origin. These findings challenge traditional views of histogenesis and tumor origin. (Cancer Res 2005; 65(11): 4633-44)

Cell cycle G 1 exit is a critical stage where cells commonly commit to proliferate or to differentiate, but the biochemical events that regulate the proliferation/differentiation (P/D) transition at G 1 exit are presently unclear. We previously showed that MAT1 (mé nage à trois 1), an assembly factor and targeting subunit of the cyclin-dependent kinase (CDK)-activating kinase (CAK), modulates CAK activities to regulate G 1 exit. Here we find that the retinoid-induced G 1 arrest and differentiation activation of cultured human leukemic cells are associated with a switch to CAK hypophosphorylation of retinoic acid receptor ␣ (RAR␣) from CAK hyperphosphorylation of RAR␣. The switch to CAK hypophosphorylation of RAR␣ is accompanied by decreased MAT1 expression and MAT1 fragmentation that occurs in the differentiating cells through the all-trans-retinoic acid (ATRA)-mediated proteasome degradation pathway. Because HL60R cells that harbor a truncated ligand-dependent AF-2 domain of RAR␣ do not demonstrate any changes in MAT1 levels or CAK phosphorylation of RAR␣ following ATRA stimuli, these biochemical changes appear to be mediated directly through RAR␣. These studies indicate that significant changes in MAT1 levels and CAK activities on RAR␣ phosphorylation accompany the ATRA-induced G 1 arrest and differentiation activation, which provide new insights to explore the inversely coordinated P/D transition at G 1 exit.The cyclin-dependent kinase (CDK) 1 -activating kinase (CAK), a trimeric CDK7-cyclin H-MAT1 (ménage à trois 1) complex, was originally implicated in cell cycle control by its ability to phosphorylate and activate CDKs (1, 2). Previous studies demonstrated that CAK regulates cell cycle G 1 exit both by phosphorylation activation of cyclin D-CDK complexes (3-7) and by phosphorylation inactivation of retinoblastoma tumor suppressor protein (pRb) (8). Also, CAK is a subcomplex of transcription factor IIH (TFIIH) (9 -12) and a kinase of TFIIH that phosphorylates the COOH-terminal domain of the largest subunit of RNA polymerase II for transcription initiation (9, 13-15). Thus, CAK is considered a cross-road regulator in linking cell cycle control with transcription. Recently, distinct regions of MAT1 have been shown to regulate CAK kinase and TFIIH transcription activities (16). To date, comprehensive studies demonstrate that MAT1 regulates CAK substrate specificity and protein-protein interactions, i.e. MAT1 mediates the association of CAK with core TFIIH and shifts CAK substrate preference from CDK2 to the COOH-terminal domain (12,14,17,18). Mice lacking MAT1 are unable to enter S phase and are defective in RNA polymerase II phosphorylation (19). Antisense abrogation of MAT1 induces cell cycle G 1 arrest (20); and MAT1 regulates the interaction and phosphorylation of CAK with tumor suppressor p53 (21), octamer transcription factors (22), pRb (8), and retinoic acid receptor ␣ (RAR␣) (23).Among the above substrates of CAK, RAR␣ is involved mainly in differentiation regulation. RAR␣ belongs to the superfamily of...

Gliomas, and in particular glioblastoma multiforme, are aggressive brain tumors characterized by a poor prognosis and high rates of recurrence. Current treatment strategies are based on open surgery, chemotherapy (temozolomide) and radiotherapy. However, none of these treatments, alone or in combination, are considered effective in managing this devastating disease, resulting in a median survival time of less than 15 months. The efficiency of chemotherapy is mainly compromised by the blood-brain barrier (BBB) that selectively inhibits drugs from infiltrating into the tumor mass. Cancer stem cells (CSCs), with their unique biology and their resistance to both radio- and chemotherapy, compound tumor aggressiveness and increase the chances of treatment failure. Therefore, more effective targeted therapeutic regimens are urgently required. In this article, some well-recognized biological features and biomarkers of this specific subgroup of tumor cells are profiled and new strategies and technologies in nanomedicine that explicitly target CSCs, after circumventing the BBB, are detailed. Major achievements in the development of nanotherapies, such as organic poly(propylene glycol) and poly(ethylene glycol) or inorganic (iron and gold) nanoparticles that can be conjugated to metal ions, liposomes, dendrimers and polymeric micelles, form the main scope of this summary. Moreover, novel biological strategies focused on manipulating gene expression (small interfering RNA and clustered regularly interspaced short palindromic repeats [CRISPR]/CRISPR associated protein 9 [Cas 9] technologies) for cancer therapy are also analyzed. The aim of this review is to analyze the gap between CSC biology and the development of targeted therapies. A better understanding of CSC properties could result in the development of precise nanotherapies to fulfill unmet clinical needs.