Project description:We recently established an orthotopic breast cancer model of brain metastasis based on the injection of murine breast cancer cell lines into the mammary fat pad. This model is based on the use of 4T1 murine breast carcinoma cells. 4T1-derived tumors recapitulate the main steps of human breast cancer progression, including epithelial-to-mesenchymal transition and metastases to lung and lymph nodes. Bioluminescence imaging revealed the appearance of secondary lesions to the lung and lymph nodes and sporadically to the brain. Brain metastases were confirmed by macroscopic and microscopic evaluation of the brains at necropsy. We then isolated brain metastatic cells, re-injected them orthotopically in syngeneic (BALB/c) mice and isolated again cell lines from brain metastatic lesions for two rounds of selection. We obtained a cell line metastasizing to the brain with 100% penetrance (named 4T1-BM2 for Brain Metastasis, 2nd generation). In parallel we derived after two rounds of in vivo growth tumor cell lines from primary tumors (4T1-T2) and from lung metastases (4T1-LM2).
Project description:The immune signaling protein NLRX1 can be either tumor promoting or tumor suppressing in different models of cancer. We demonstrate that in a mammary tumor model of triple-negative breast cancer, NLRX1 impacts tumor volume and lung metastasis. We used this microarray to understand what genes and pathways are impacted by NLRX1 in murine triple-negative mammary tumors to produce the in vivo phenotypes we observed. Abstract from associated publication: Prior studies have defined multiple, but inconsistent, roles for NLRX1 in regulating cancer-associated biological functions. Here, we explore the role of NLRX1 in the highly-metastatic murine 4T1 mammary tumor model. Using Nlrx1-/- mice engrafted with 4T1 tumors, we demonstrate that NLRX1 functions as a tumor suppressor when expressed in healthy host cells. Specifically, NLRX1 attenuates tumor growth and metastasis through suppressing epithelial-mesenchymal transition, tumor-associated eosinophil recruitment, and the lung metastatic niche. Conversely, we demonstrate that NLRX1 functions as a tumor promoter when expressed in 4T1 tumor cells using gain- and loss-of-function studies. Mechanistically, NLRX1 augments 4T1 aggressiveness through regulating epithelial-mesenchymal transition, cell death, proliferation, migration, ROS levels, and mitochondrial respiration. Together, we provide critical insight into NLRX1 function in breast cancer and establish cellular context as the director of the dichotomous role of NLRX1 in mammary tumor metastasis.
Project description:Comparative analysis of the transcriptome of primary tumors generated from 4T1 cells transduced with a lentiviral vector expressing a siRNA against murine SPARC (4T1-C18), primary tumors generated from 4T1 cells transduced with a lentiviral vector expressing a scramble sequence (4T1-SCR) or lung metastasis foci from 4T1-SCR tumor-bearing mice (4T1-SCR MTTS).
Project description:Comparative analysis of the transcriptome of primary tumors generated from 4T1 cells transduced with a lentiviral vector expressing a siRNA against murine SPARC (4T1-C18), primary tumors generated from 4T1 cells transduced with a lentiviral vector expressing a scramble sequence (4T1-SCR) or lung metastasis foci from 4T1-SCR tumor-bearing mice (4T1-SCR MTTS). Three experimental conditions, 4T1-C18, 4T1-SCR and 4T1-SCR MTTS. Biological replicates: 4 4T1-C18, 4 4T1-SCR, 4 4T1-SCR MTTS independently grown in different mice. 2 days-old tumors and 30 days old lung foci. One replicate per array. All microarrays were processed the same day
Project description:Metastasis is a multistage process that requires cancer cells to escape from the primary tumor, survive in the circulation, seed at distant sites and colonize these foreign tissue environments. Each of these processes involves rate-limiting steps that are influenced by stromal cells of the tumor microenvironment. While the tumor microenvironment has emerged as a major regulator of cancer progression in other organ sites, our knowledge of the brain metastatic microenvironment is currently very limited. Thus, we aim to dissect signatures of tumor-stroma interactions in brain metastasis in order to identify factors that regulate the homing, seeding and outgrowth of cancer cells in this highly specialized microenvironment. We took advantage of an experimental metastasis model in which variants of the human breast cancer line MDA-MB-231 home to the brain in xenografted animals. To simultaneously capture gene expression changes in the tumor and stromal compartment, we used a dual species-specific microarray platform, the HuMuProtIn array, to discriminate between differentially expressed protease or protease inhibitor genes of human (tumor) or murine (stromal) origin. RNA was isolated from early and late brain, bone and lung metastases from xenograft models of breast metastasis. RNA was also isolated from non-tumor-burdened mouse brain, bone and lung as normal tissue controls. RNA from tissue homing cell lines was isolated in vitro to serve as a control for the human-derived RNA. Samples were collected from 24 total tumor-burdened mice, with 3 replicates for each condition and control. A total of 36 samples are included here.
Project description:Breast cancer brain metastasis remains largely incurable. While several mouse models have been developed to investigate the genes and mechanisms regulating breast cancer brain metastasis, these models often lack clinical relevance since they require the use of immune-compromised mice and/or are poorly metastatic to brain from the mammary gland. We describe the development and characterization of an aggressive brain metastatic variant of the 4T1 syngeneic model (4T1Br4) that spontaneously metastasises to lung, bone and brain but is selectively more metastatic to the brain from the mammary gland than parental 4T1 tumors. The 4T1Br4 model will provide a clinically relevant tool to evaluate novel therapies against brain metastasis.
Project description:Brain metastasis is one of the most feared complications of cancer and the most common intracranial malignancy in adults. Its underlying mechanisms remain unknown. From breast cancer patients with metastatic disease we isolated cell populations that aggressively colonize the brain. Transcriptomic analysis of these cells yielded overlapping gene sets whose expression is selectively associated with brain metastasis. The expression of seventeen of these genes in primary breast tumors is associated with brain relapse in breast cancer patients. Some of these genes are also associated with metastasis to lung but not to liver, bone or lymph nodes, providing a molecular basis for the long-observed link between brain and lung metastasis. Among the functionally validated brain metastasis genes, the cyclooxigenase COX-2, the EGFR ligand HB-EGF, and the brain-specific 2-6 sialyltransferase ST6GALNAC5 mediate cancer cell passage through the blood-brain barrier. Other brain metastasis genes encode inflammatory factors and brain-specific proteolytic regulators, suggesting a multifaceted program for breast cancer colonization of the brain. Experiment Overall Design: 204 primary tumors from breast cancer patients with known site of relapse were studied, focussing on brain relapse versus other relapse. Identified genes were validated in this cohort.
Project description:Metabolic rewiring is essential for breast tumor growth and progression to metastatic disease, yet little is known regarding how cancer cells modify their acquired metabolic programs in response to different metastatic microenvironments. Transcriptional and metabolomic analysis have previously shown that liver-metastatic breast cancer cells adopt an intrinsic metabolic profile characterized by increased HIF-1α activity and dependence on glycolysis. Stable isotope tracing analysis (SITA) performed in vivo confirmed that the glycolytic nature of liver-metastatic breast cancer cells is retained when these cells are grown as primary tumors or as liver metastases. However, our data also reveal that unique metabolic adaptations are specifically induced by the liver microenvironment. Indeed, liver metastases display elevated expression of genes involved in glutathione (GSH) biosynthesis and reactive oxygen species (ROS) detoxification when compared to primary tumors. Moreover, breast cancer liver metastases rely strongly on glucose and glutamine-derived carbons to support de novo GSH synthesis. Glutathione is a tripeptide that acts as a major scavenger for reactive oxygen species (ROS). Liver metastases display reduced levels of 8-Oxo-2'-deoxyguanosine, confirming their increased capacity to buffer ROS. We demonstrated the dependence of liver metastases formation on these distinct metabolic adaptations by depleting glutamate-cysteine ligase (Gcl), the rate-limiting enzyme in glutathione biosynthesis. Gcl depletion, and decreased GSH levels, strongly reduced the capacity of liver-metastatic cells to form distant metastasis within the liver. We performed gene expression analysis of liver metastasis and primary tumors from liver-metastatic breast cancer cells derived from 4T1 cells. 4T1-2776 (76) and 4T1-2792 (92) cells were injected in the mammary fat pads of BALB/c and grown as primary tumors or were grown as liver metastasis after splenic injection. Tissues were harvested from primary tumors and liver metastasis and submitted to laser-capture microdissection (LCM). For liver metastasis, tumour tissue was harvested at 10 days, 2 weeks and 3 weeks after splenic injection. For each time point, tissue was isolated from the tumor centre (core), a peripheral area of the tumor (margin), a region of the liver proximal to the tumor (adjacent) and a region of the liver far from the tumor (distant). For primary tumors from 4T1-2776 cells (1034, 1036, 1043) and 4T1-2792 (MFP2L, MFP3L, MFP5L) tissue was collected from the tumor core and margin, at the experimental endpoint.
Project description:To elucidate molecular mechanisms underlying brain metastasis-promoting function of Cdk5, two analyses were performed. In the first analysis, we screened for Cdk5 substrates in brain-seeking breast cancer cell lines 4T1.Br3 and T11.Br1, transfected with shRNA targeting Cdk5 mRNA (100% knockdown) or control. T11.Br1 and 4T1.Br3 cells (shCDK5 or shCtl) were cultured for 6 days in the presence of labelled arginine and lysine from the SILAC Protein Quantitation Kit. For the second analysis, we performed a quantitative label-free mass-spectrometry analysis of astrocytes’ conditioned media pre-educated by 4T1.Br3 cell-derived CM for 72 h. For the second analysis, we performed a quantitative label-free mass-spectrometry analysis of astrocytes’ conditioned media pre-educated by 4T1.Br3 cell-derived CM for 72 h.
Project description:We utilized 3D-organotypic cultures whose physical properties were altered by inclusiong of type I collagen to create biomechanically rigid microenvironments that approximated those typically observed in primary mammary tumors. Compliant 3D-organotypic cultures were also generated to recapitulate the biomechanical properties of pulmonary microenvironments typically encountered by disseminated breast carcioma cells. The murine 4T1 progression series represents an established model of triple negative breast cancer development and metastasis and consists of isogenically-derived nonmetastatic 67NR, systemically invasive 4TO7, and highly metastatic 4T1 cells that were propagated for 6 days in the absense or presense of TGF-beta in either rigid or compliant 3D-cultures. Afterward, total RNA was extracted and subjected to miRNA profiling. two replicates of each growth and treatment condition for each cell line.