Cancer Biology

The mammary gland undergoes extensive remodeling during pregnancy and is also subject to neoplastic processes both of which result in histological changes of the gland epithelial structure. Since the mammary tree is a complex three-dimensional structure a method is needed that provides an overview of the entire gland. Whole mounts provide this information, are inexpensive and do not require specialized equipment. This protocol describes mammary gland isolation, whole mount preparation and analysis. Mammary gland tissue, which is removed postmortem, is stained with Carmine Alum, a nuclear stain, allowing detection of epithelial structures embedded in the adipose tissue of the mammary fat pad. Stained mammary glands are imaged by light microscopy or embedded and sectioned for histological examination. Image analysis software such as Image J can be used to quantify extensity of branching complexity, epithelial structure remodeling or hyperplastic changes.

Murine tumor models have been critical to advances in our knowledge of tumor physiology and for the development of effective tumor therapies. Essential to these studies is the ability to both track tumor development and quantify tumor burden in vivo. For this purpose, the introduction of genes that confer tumors with bioluminescent properties has been a critical advance for oncologic studies in rodents. Methods of introducing bioluminescent genes, such as firefly luciferase, by viral transduction has allowed for the production of tumor cell lines that can be followed in vivo longitudinally over long periods of time. Here we describe methods for the production of stable luciferase expressing tumor cell lines by lentiviral transduction.

To investigate whether endothelial Akt1 activation is sufficient to induce vascular tumor formation in the skin, we have developed a skin graft model in which a skin fragment from transgenic donor mice with inducible and endothelial cell-specific overexpression of activated Akt1 (myrAkt1) is grafted into the skin of wild type recipient mice. The donor skin successfully engrafts after two weeks and, more importantly, vascular tumor develops at the site of transgenic skin graft when myrAkt1 expression is turned on. This skin graft model is a novel approach to investigate the biological impact of a key signal transduction molecule in a temporal, localized and organ-specific manner.

Patient-derived xenograft (PDX) models for cancer research have recently attracted considerable attention in both the academy and industry (Hidalgo et al., 2014; Wilding and Bodmer, 2014). PDX models have been developed from different tumor types including lung cancer to improve the drug development process. These models are used for pre-clinical drug evaluation and can be used for the predictive results of clinical outcomes because they conserve original tumor characteristics such as heterogeneity, complexity and molecular diversity (Kopetz et al., 2012). Additionally, PDX model provides the potential tool for the personalized drug therapy. In this protocol, we present methods for the establishment of PDX in mice using primary tumor tissues from patients with small cell lung cancer (SCLC).

Obesity has been linked to breast cancer progression but the underlying mechanisms remain obscure. Being overweight or obese for a woman at the time she is diagnosed with breast cancer is linked to a high risk of recurrence regardless of treatment factors. In rodents, high body weight is also associated with increased incidence of spontaneous and chemically induced tumors. To study the complex interaction between the mammary epithelia and the microenvironment, with a focus on the mechanism underlying the role obesity plays in the regulation of the cancer stem cell traits and the development of mammary cancer in vivo, we have established a diet-induced obesity (DIO) rat model of breast cancer (Chang et al., 2015).

Over the past decade, in vivo bioluminescent imaging has emerged as a non-invasive and sensitive tool for studying ongoing biological processes within living organisms (Contag et al., 1997; Contag et al., 1998). Based on the detection and quantitation of the photons produced by the oxidation of luciferin by luciferase enzymes (Harvey, 1927), this technique has proved to be particularly useful in analyzing cancerous cells and monitoring tumor growth (Edinger et al., 1999; Sweeney et al., 1999; Vidal et al., 2015), providing a cost-effective insight into how the disease progresses in vivo, without the need of serial sacrifice of animals. This protocol describes in detail the procedure of obtaining luciferase-tagged tumors in immunocompromised mice that can be studied by bioluminescent imaging through the use of an IVIS Spectrum imager.

Accurate live tumor imaging in mice is now possible by means of high-resolution positron emission tomography (micro-PET) and X-ray computed tomography (micro-CT). By providing a powerful tool to examine biological samples with complex structure in vivo, this technology generated a significant advance in the cancer research field, particularly regarding the ability to perform longitudinal studies in combination with a therapeutic intervention. Here, we describe methods to optimize visualization of murine lung tumors by micro-PET, micro-CT and combined micro-PET-CT.

Medullary thyroid cancers (MTCs) are derived from calcitonin-producing cells (C cells) of neuroendocrine origin. Rb heterozygous mice develop low-grade C cell adenocarcinoma following biallelic inactivation of the Rb tumor suppressor gene loci. Additional inactivation of another tumor suppressor gene such as Trp53, Arf or Cdkn1a allows Rb-deficient mice to generate more aggressive C cell adenocarcinoma (Takahashi et al., 2006; Shamma et al., 2009; Kitajima et al., 2015). To characterize C cell adenocarcinoma cells derived from Rb-deficient mice of different genetic backgrounds, we attempted to extract C cell adenocarcinoma cells from primary thyroid tumor tissue. Since primary mouse small cell lung cancer (SCLC) cells those originate in neuroendocrine cells that also stems C cells, can be established both as non-adhesive and adhesive cells (Calbo et al., 2011), we applied their method to MTCs. Here we describe our isolation technique for non-adhesive and adhesive cell cultures from primary medullary thyroid tumor tissue. We found that the molecular markers of C cell such as Calcitonin and Ascl1 are predominantly enriched in the non-adhesive population (Kitajima et al., 2015). This is in line with the fact that one of most commonly distributed human MTC cell line TT is non-adhesive.

Hanging drop assay can be used to investigate cell-cell cohesion and cell-substratum adhesion through generation of 3D spheroids under physiological conditions. It also can be used to elucidate the role of cell-cell or cell-ECM interactions in specifying spatial relationships between two (or more) different cell populations. This simple method requires no specialized equipment and provides a means of generating tissue-like cellular aggregates for measurement of biomechanical properties for molecular and biochemical analysis in a physiologically relevant model.