**Part 3**

**Glioma Progression** 

222 Glioma – Exploring Its Biology and Practical Relevance

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Herndon, J., Kinzler, K. W., Velculescu, V. E., Vogelstein, B. & Bigner, D. D. (2009). IDH1 and IDH2 mutations in gliomas. *N Engl J Med*, Vol. 360, No. 8, pp.

**11** 

*U.S.A.* 

**Migration and Invasion of Brain Tumors** 

Recent advances in molecular biology have led to new insights in the development, growth and infiltrative behaviors of primary brain tumors (Demuth and Berens, 2004; Huse and Holland, 2010; Johnson et al., 2009; Kanu et al., 2009). These tumors are derived from various brain cell lineages and have been historically classified on the basis of morphological and, more recently, immunohistochemical features with less emphasis on their underlying molecular pathogenesis (Huse and Holland, 2010). The detailed molecular characterization of brain tumors has laid the groundwork for augmentation of standard treatment with patient-specific designed targeted therapies (Johnson et al., 2009; Kanu et al., 2009). Nevertheless, these tumors are extremely aggressive in their infiltration of brain tissue (Altman et al., 2007; Hensel et al., 1998; Yamahara et al., 2010), as well as in their metastasis outside of brain (Algra et al., 1992). Further, it now appears that the physiological conditions of the normal brain itself constitute a biological environment conducive to the uncontrolled dissemination of primary tumors (Bellail et al., 2004; Sontheimer, 2004). This review surveys the latest research on the invasive behavior of two major types of primary brain tumors: gliomas and medulloblastomas - the most common tumors diagnosed within adult and pediatric brain, respectively (Rickert and Paulus, 2001). The material has been divided into five sections: i) Characteristics of malignant brain tumors; ii) Mechanisms of tumor cell migration; iii) Models for the study of brain tumor invasion *in vivo* and *ex vivo*; iv) Models for the study of brain tumor invasion *in vitro*; and v) Future prospects of anti-invasive brain

Gliomas, commonly found in the anterior cerebral hemisphere, are a group of tumors derived from glial cells - the most abundant cells in the brain (Larjavaara et al., 2007; Lim et al., 2007; Louis et al., 2007). They are classified based on well-characterized histological features (Louis, 2006; Scheithauer, 2009; Trembath et al., 2008). The World Health Organization (WHO) defines gliomas by cell type, location and grade, and categorizes them into four classes (Lassman, 2004): i) Grade I tumors, or pilocytic astrocytomas; ii) Grade II tumors, also called low-grade astrocytomas; iii) Grade III tumors, or anaplastic astrocytomas; and iv) Grade IV tumors, also known as glioblastoma multiforme (GBM).

**1. Introduction** 

tumor therapy.

\* Contributed equally

**2. Characteristics of malignant brain tumors** 

Richard A. Able, Jr.\*, Veronica Dudu\* and Maribel Vazquez

*The City College of The City University of New York (CCNY)* 

*Department of Biomedical Engineering* 
