Animal models for basic and preclinical research in bladder cancer

EIJAN, ANA MARIA; LODILLINSKY, CATALINA; SANDES, EDUARDO

Bladder Cancer

InTech - Open Access Publisher

Lugar: 51000 Rijeka, University Campus STeP Ri, ; Año: 2011; p. 1 - 25

Bladder cancer is one of the most common cancers in the world. In 2006 there were about 61,240 diagnosed cases of bladder cancer and approximately 13,060 deaths attributable to this disease, being the estimated prevalence worldwide more than 1,000,000 patients (Jemal et al., 2006; Lerner, 2005). Taking into account incidence seems to be increasing; bladder cancer is clearly a significant public health issue around the world. Thus, it is necessary to intensify research in this topic. Urinary bladder cancer is originates predominately from epithelial cells of the urothelium (Lopez-Beltran et al., 2004; Montironi et al., 2005). The majority of bladder cancers, about 70%, are initially diagnosed without muscle invasion (pTa and pT1), know as superficial bladder cancer. In this case the simple transurethral resection is sufficient to remove tumor. However, some patients experience recurrences or yet tumor progression.  (figure I a: HE de la vejiga) Progression of tumor involves invasion of tumor cells, penetrating deeper layers of the bladder such as detrusor muscle (pT2), perivesical tissue (pT3) and extravesical organs (pT4). This progression commits the patient´s life, and it is necessary to apply more aggressive therapies (Sobin et al., 1997). (figura IB sobre una HE poner las grados de invasion) As in most tumors, in the bladder cancer, intensive research on it are being carried out to elucidate the reason for the appearance of tumors, which factors are involved in the development of tumors, which are related to tumoral progression process. These investigations provide insight into the biology of the tumor, this knowledge is essential to do research on the implementation of new therapeutic and / or preventive modalities (Bhattacharya et al., 2010; Zhang et al., 2011). Research in basic science covers the mechanisms that lead cell towards transformation and develop cancer, using simple experimental models where it is easier to interpret the results. Cell cultures techniques, are widely used to study different oncological processes. The cell culture is the growth of any cell type, usually tumor cells, in plastic bottles with nutrient-containing solutions. The cells grow attached to plastic surface forming monolayer, usually in a two-dimensional way. With using this technique is possible to study processes such as mutagenesis, invasion, migration, production of proteolytic enzymes, among others. Although culture cell is a very important tool has certain limitations. Many biological processes depend on the three-dimensional architecture. In addition, monolayer culture in general is restricted to a single cell type or at most two. While, tumors are complex and consist of tumor cells and other cell types such as stroma and immune cells that interact to promote or inhibit tumor growth. To overcome these limitations it is necessary to widen the model towards three-dimensional models, such as tissue or organs cultures (Varley et al., 2011). The next step in the investigation, to corroborate in vitro results, is the assay in a living organism. Animal models are an important tool for studying mechanisms of carcinogenesis as well as for preclinical studies of new therapeutic modalities. It is important to design a model as similar to human disease as possible, so that observations can be readily transferred to clinical studies.