transforming-growth-factor-beta and Bone-Marrow-Neoplasms

In a significant fraction of breast cancer patients, distant metastases emerge after years or even decades of latency. How disseminated tumour cells (DTCs) are kept dormant, and what wakes them up, are fundamental problems in tumour biology. To address these questions, we used metastasis assays in mice and showed that dormant DTCs reside on microvasculature of lung, bone marrow and brain. We then engineered organotypic microvascular niches to determine whether endothelial cells directly influence breast cancer cell (BCC) growth. These models demonstrated that endothelial-derived thrombospondin-1 induces sustained BCC quiescence. This suppressive cue was lost in sprouting neovasculature; time-lapse analysis showed that sprouting vessels not only permit, but accelerate BCC outgrowth. We confirmed this surprising result in dormancy models and in zebrafish, and identified active TGF-β1 and periostin as tumour-promoting factors derived from endothelial tip cells. Our work reveals that stable microvasculature constitutes a dormant niche, whereas sprouting neovasculature sparks micrometastatic outgrowth.

Topics: Animals; Bone Marrow Neoplasms; Brain Neoplasms; Breast Neoplasms; Cell Adhesion Molecules; Endothelium, Vascular; Female; Fluorescent Antibody Technique; Humans; Lung Neoplasms; Mice; Neoplasm, Residual; Neovascularization, Pathologic; Pericytes; Stem Cell Niche; Thrombospondin 1; Transforming Growth Factor beta; Tumor Cells, Cultured; Tumor Microenvironment; Zebrafish

Metastasis is the rapid proliferation of cancer cells (secondary tumour) at a specific place, generally leading to death. This occurs at anatomical parts providing the necessary environment for vascularity, oxygen and food to hide their actions and trigger the rapid growth of cancer. Prostate and breast cancers, for example, use bone marrow for their proliferation. Bone-supporting cancer cells thus adapt to the environment, mimicking the behaviour of genetic and molecular bone cells. Evidence of this has been given in Cecchini et al. (2005, EAU Update Ser. 3:214-226), providing arguments such as how cancer cell growth is so active during bone reabsorption. This paper simulates metastasis activation in bone marrow. A mathematical model has been developed involving the activation of molecules from bone tissue cells, which are necessary for cancer to proliferate. Here, we simulate two forms of secondary tumour growth depending on the type of metastasis: osteosclerosis and osteolysis.

Topics: Biomedical Engineering; Bone Marrow Neoplasms; Bone Neoplasms; Bone Remodeling; Cell Differentiation; Cell Proliferation; Computer Simulation; Humans; Mathematical Concepts; Models, Biological; Neoplasm Metastasis; Osteolysis; Osteosclerosis; Parathyroid Hormone-Related Protein; Somatomedins; Transforming Growth Factor beta

Epithelial-mesenchymal transition (EMT) is a normal developmental program that is considered to also play an important role in cancer metastasis. Ultimate inducers of EMT are transcriptional repressors that individually can induce experimental EMT, yet in many cells, particularly cancer cells, multiple inducers are expressed simultaneously. Why, and if, and how they interact to regulate EMT is unanswered. Using RNA interference technology to affect protein knockdown and avoid potential overexpression artifact coupled with transient TGFβ treatment to better mimic in vivo conditions we show, in both nontumorigenic and tumorigenic epithelial cancer cells, that Snail1 is uniquely required for EMT initiation, whereas Twist1 is required to maintain late EMT. Twist1, present in resting epithelial cells, is dispensable for EMT initiation. Mechanistically, in response to transient TGFβ treatment, transient Snail1 expression represses Twist1 transcription directly, which is subsequently upregulated, as Snail1 levels decrease, to sustain E-cadherin downregulation and growth arrest of EMT. Persistent Twist1 expression is associated with a p38 and extracellular signal-regulated kinase signal feedback loop that sustains growth-inhibitory signals characteristic of quiescent micrometastatic tumors. This Snail1-Twist1 temporal and spatial cooperation was also observed in vivo during human breast cancer progression to metastasis. Twist1 level, but not Snail1 level, and Twist1:Snail1 ratio in disseminated micrometastatic bone marrow tumor cells was found to correlate with survival and treatment resistance and is highly predictive of metastatic or recurrent disease.

Topics: Bone Marrow Neoplasms; Breast Neoplasms; Cell Dedifferentiation; Cell Transformation, Neoplastic; Epithelial Cells; Epithelial-Mesenchymal Transition; Female; Gene Expression Regulation, Neoplastic; Gene Knockdown Techniques; Humans; MAP Kinase Signaling System; Nuclear Proteins; Prognosis; Promoter Regions, Genetic; Protein Binding; Recurrence; RNA Interference; Signal Transduction; Snail Family Transcription Factors; Transcription Factors; Transforming Growth Factor beta; Twist-Related Protein 1

The RRR-alpha-tocopheryl succinate form of vitamin E, referred to as vitamin E succinate (VES), inhibits the proliferation of avian reticuloendotheliosis virus-transformed RECC-UTC4-1 (C4-1) lymphoblastoid cells in a dose-dependent manner in vitro. Analyses of conditioned medium (CM) from VES growth-inhibited cells revealed a potent antiproliferative activity. Characterization of the antiproliferative activity as transforming growth factor-beta (TGF-beta) was established by 1) growth inhibition of TGF-beta-responsive Mv1Lu mink lung and murine CTLL-2 cell lines, 2) a combination of physical characteristics including heat stability, acid stability, and Bio-Gel P-60 column chromatography elution profile, 3) neutralization of the antiproliferative activity by antibodies specific for TGF-beta, and 4) immunoprecipitation of metabolically labeled TGF-beta in CM from VES-treated C4-1 cells by use of TGF-beta-specific antibodies. Northern blot analyses of total cellular RNA revealed that VES does not alter the levels of constitutively expressed TGF-beta isoform-specific mRNAs; namely, VES does not alter the levels of the 3.9- and 4.1-kb TGF-beta 2 mRNAs, the 3.0-kb TGF-beta 3 mRNA, or the 2.5-, 2.7-, and 1.7-kb TGF-beta 4 mRNAs. The data show that VES inhibits C4-1 cell proliferation and induces the cells to produce and secrete active forms of TGF-beta, suggesting that one mechanism whereby VES inhibits C4-1 cell proliferation may be via the TGF-beta pathway for cellular growth control.

Topics: Animals; Antineoplastic Agents; Birds; Bone Marrow; Bone Marrow Neoplasms; Cell Division; Cell Line, Transformed; Culture Media, Conditioned; DNA, Neoplasm; Retroviridae; RNA, Messenger; Tocopherols; Transcription, Genetic; Transforming Growth Factor beta; Vitamin E