Studying Triple Negative Breast Cancer Using Orthotopic Breast Cancer Model

Abstract

Triple-negative breast cancer (TNBC) is an aggressive breast cancer subtype with limited therapeutic options. When compared to patients with less aggressive breast tumors, the 5-year survival rate of TNBC patients is 77% due to their characteristic drug-resistant phenotype and metastatic burden. Toward this end, murine models have been established aimed at identifying novel therapeutic strategies limiting TNBC tumor growth and metastatic spread. This work describes a practical guide for the TNBC orthotopic model where MDA-MB-231 breast cancer cells suspended in a basement membrane matrix are implanted in the fourth mammary fat pad, which closely mimics the cancer cell behavior in humans. Measurement of tumors by caliper, lung metastasis assessment via in vivo and ex vivo imaging, and molecular detection are discussed. This model provides an excellent platform to study therapeutic efficacy and is especially suitable for the study of the interaction between the primary tumor and distal metastatic sites. Video Link The video component of this article can be found at https://www.jove.com/video/60316/ 4 , and direct liver injection 5 have also been employed. The direct blood circulation injection is often referred to as an artificial metastasis model, which is quick and easy but less physiologically accurate because it circumvents tumor escape from the primary lesion and intravasation 6,7,8. When compared to direct injection models, the orthotopic breast cancer model takes longer for the occurrence of detectable metastatic lesions in remote organs such as the lung, but it is more physiologically relevant because it closely mimics the multistep metastatic process as it occurs in humans. Importantly, a 2013 study 9 compared the tail vein injection and orthotopic models and found that the breast cancer cells injected into the tail vein and those isolated from lung metastatic lesions after tail vein injection exhibited similar global gene expression profiles. In contrast, the global gene expression profile of orthotopically injected breast cancer cells was dramatically different than that of lung metastatic lesions arising from orthotopically injected cells 9. These observations suggest that the orthotopic model is more physiologically relevant, because the metastatic lesions undergo a selection process similar to the multistep process of metastasis as it occurs in humans. This work describes an orthotopic breast cancer (MDA-MB-231-Luc/GFP) model in nude mice that was optimized in our laboratory for imaging detection techniques as well as the identification of novel biomarkers and development of targeted chemotherapeutic agents.

Nitric Oxide Modulates Metabolic Processes in the Tumor Immune Microenvironment

“…In addition, redox regulated signaling has provided new strategies to enhance cancer therapy that have included modification of signal transduction, immune signaling, inhibition of nitric oxide synthase 2 (NOS2), and cyclooxygenase 2 (COX2), which have all shown promise in preclinical and even clinical trials [4][5][6]. Furthermore, NOS2/COX2 are linked to poor outcome and collaborate in feedforward loops in both cancer and immune cells in several tumor types, with ER-breast cancer being the best example [7][8][9][10][11][12][13][14][15][16][17][18]. Importantly, the collaboration of these two enzymes involving an array of oncogenic signaling mechanisms in the promotion of disease progression was recently reported [7].…”

ASAH1 facilitates TNBC by DUSP5 suppression-driven activation of MAP kinase pathway and represents a therapeutic vulnerability

“…This experimental model has the advantage of mirroring several aspects of breast cancer development as it occurs in humans. Further, this experimental approach also allows the modeling of the multistep metastatic process, which occurs in humans [42]. We engrafted the F-Luc-labeled MDA-MB-231 (F-Luc-MDA-MB-231) TNBC cells orthotopically into the mammary fat pad of female NSG mice.…”