ABSTRACT
Improved targeted therapies are needed to combat metastatic prostate cancer. Here, we report the identification of the spleen kinase SYK as a mediator of metastatic dissemination in zebrafish and mouse xenograft models of human prostate cancer. Although SYK has not been implicated previously in this disease, we found that its expression is upregulated in human prostate cancers and associated with malignant progression. RNAi-mediated silencing prevented invasive outgrowth in vitro and bone colonization in vivo, effects that were reversed by wild-type but not kinase-dead SYK expression. In the absence of SYK expression, cell surface levels of the progression-associated adhesion receptors integrin α2ß1 and CD44 were diminished. RNAi-mediated silencing of α2ß1 phenocopied SYK depletion in vitro and in vivo, suggesting an effector role for α2ß1 in this setting. Notably, pharmacologic inhibitors of SYK kinase currently in phase I-II trials for other indications interfered similarly with the invasive growth and dissemination of prostate cancer cells. Our findings offer a mechanistic rationale to reposition SYK kinase inhibitors for evaluation in patients with metastatic prostate cancer.
Subject(s)
Intracellular Signaling Peptides and Proteins/antagonists & inhibitors , Intracellular Signaling Peptides and Proteins/genetics , Prostatic Neoplasms/enzymology , Prostatic Neoplasms/therapy , Protein Kinase Inhibitors/pharmacology , Protein-Tyrosine Kinases/antagonists & inhibitors , Protein-Tyrosine Kinases/genetics , Animals , Cell Line, Tumor , HEK293 Cells , Heterografts , Humans , Intracellular Signaling Peptides and Proteins/deficiency , Intracellular Signaling Peptides and Proteins/metabolism , Male , Mice , Mice, Inbred BALB C , Mice, Nude , Molecular Targeted Therapy , Prostatic Neoplasms/genetics , Prostatic Neoplasms/pathology , Protein-Tyrosine Kinases/deficiency , Protein-Tyrosine Kinases/metabolism , RNA, Small Interfering/administration & dosage , RNA, Small Interfering/genetics , Syk Kinase , ZebrafishABSTRACT
Interactions with the extracellular matrix (ECM) through integrin adhesion receptors provide cancer cells with physical and chemical cues that act together with growth factors to support survival and proliferation. Antagonists that target integrins containing the ß1 subunit inhibit tumor growth and sensitize cells to irradiation or cytotoxic chemotherapy in preclinical breast cancer models and are under clinical investigation. We found that the loss of ß1 integrins attenuated breast tumor growth but markedly enhanced tumor cell dissemination to the lungs. When cultured in three-dimensional ECM scaffolds, antibodies that blocked ß1 integrin function or knockdown of ß1 switched the migratory behavior of human and mouse E-cadherin-positive triple-negative breast cancer (TNBC) cells from collective to single cell movement. This switch involved activation of the transforming growth factor-ß (TGFß) signaling network that led to a shift in the balance between miR-200 microRNAs and the transcription factor zinc finger E-box-binding homeobox 2 (ZEB2), resulting in suppressed transcription of the gene encoding E-cadherin. Reducing the abundance of a TGFß receptor, restoring the ZEB/miR-200 balance, or increasing the abundance of E-cadherin reestablished cohesion in ß1 integrin-deficient cells and reduced dissemination to the lungs without affecting growth of the primary tumor. These findings reveal that ß1 integrins control a signaling network that promotes an epithelial phenotype and suppresses dissemination and indicate that targeting ß1 integrins may have undesirable effects in TNBC.
Subject(s)
Extracellular Matrix/metabolism , Integrin beta1/metabolism , Lung Neoplasms/secondary , Neoplasm Metastasis/physiopathology , Signal Transduction/physiology , Triple Negative Breast Neoplasms/physiopathology , Animals , Blotting, Western , Cadherins/metabolism , Cell Line, Tumor , Cell Movement/physiology , DNA-Binding Proteins/genetics , Flow Cytometry , Gene Silencing , Homeodomain Proteins/metabolism , Humans , Immunohistochemistry , Integrin beta1/genetics , Luciferases , Mice , Mice, Knockout , MicroRNAs/metabolism , Repressor Proteins/metabolism , Time-Lapse Imaging , Transforming Growth Factor beta/metabolism , Triple Negative Breast Neoplasms/metabolism , Zebrafish , Zinc Finger E-box Binding Homeobox 2ABSTRACT
Radiotherapy is one of the treatment options for locally or regionally advanced prostate cancer, but radioresistance of prostate cancer cells is a practical limitation of radiotherapy. The identification of molecular targets of radioresistance in prostate cancer is important to improve therapeutic intervention. The aim of this review is to give more biological insight into some well known processes involved in radioresistance of prostate cancer especially Apoptotic pathway; DNA damage response; and NF- κB(nuclear factor kappalight- chain-enhancer of activated B cells) signaling pathway. This review integrates salient, published, research findings with underlying molecular mechanisms, preclinical efficacy, and potential clinical applications of combining radiotherapy with these molecular targeted agents for the treatment of prostate cancer.
Subject(s)
Prostatic Neoplasms/radiotherapy , Radiation-Sensitizing Agents/therapeutic use , DNA Damage , Humans , Male , NF-kappa B/metabolism , Prostatic Neoplasms/genetics , Prostatic Neoplasms/metabolism , Proto-Oncogene Proteins c-bcl-2/drug effects , Radiation-Sensitizing Agents/pharmacologyABSTRACT
A quantitative bio-imaging platform is developed for analysis of human cancer dissemination in a short-term vertebrate xenotransplantation assay. Six days after implantation of cancer cells in zebrafish embryos, automated imaging in 96 well plates coupled to image analysis algorithms quantifies spreading throughout the host. Findings in this model correlate with behavior in long-term rodent xenograft models for panels of poorly- versus highly malignant cell lines derived from breast, colorectal, and prostate cancer. In addition, cancer cells with scattered mesenchymal characteristics show higher dissemination capacity than cell types with epithelial appearance. Moreover, RNA interference establishes the metastasis-suppressor role for E-cadherin in this model. This automated quantitative whole animal bio-imaging assay can serve as a first-line in vivo screening step in the anti-cancer drug target discovery pipeline.
Subject(s)
Diagnostic Imaging , Neoplasm Transplantation , Neoplasms/pathology , Animals , Breast Neoplasms/pathology , Cell Line, Tumor , Colorectal Neoplasms/pathology , Diagnostic Imaging/methods , Drug Discovery/methods , Female , Humans , Male , Microarray Analysis , Prostatic Neoplasms/pathology , Transplantation, Heterologous , ZebrafishABSTRACT
Cell spheroids (CS) embedded in 3D extracellular matrix (ECM) serve as in vitro mimics for multicellular structures in vivo. Such cultures, started either from spontaneous cell aggregates or single cells dispersed in a gel are time consuming, applicable to restricted cell types only, prone to high variation, and do not allow CS formation with defined spatial distribution required for high-throughput imaging. Here, we describe a method where cell-polymer suspensions are microinjected as droplets into collagen gels and CS formation occurs within hours for a broad range of cell types. We have automated this method to produce CS arrays in fixed patterns with defined x-y-z spatial coordinates in 96 well plates and applied automated imaging and image analysis algorithms. Low intra- and inter-well variation of initial CS size and CS expansion indicates excellent reproducibility. Distinct cell migration patterns, including cohesive strand-like - and individual cell migration can be visualized and manipulated. A proof-of-principle chemical screen is performed identifying compounds that affect cancer cell invasion/migration. Finally, we demonstrate applicability to freshly isolated mouse breast and human sarcoma biopsy material - indicating potential for development of personalized cancer treatment strategies.
Subject(s)
Extracellular Matrix/chemistry , Neoplasms/diagnosis , Polymers/chemistry , Tissue Scaffolds/chemistry , Animals , Cell Line, Tumor , Cell Movement/physiology , Humans , In Vitro Techniques , Mice , Microinjections , Spheroids, CellularABSTRACT
PURPOSE: Tumours are composed of a heterogeneous cell population. Cancer stem cells, which make up a minor fraction of a tumour, may be the cells that initiate and sustain tumour growth. Cancer stem cells are believed to share many properties with normal stem cells that render them relatively insensitive to classical radio- and chemotherapy. CONCLUSIONS: We discuss what those (cancer) stem cell properties are and how the interactions with the microenvironment--'the niche'--control those aspects of (cancer) stem cell biology. We also describe possible strategies to target cancer stem cells in order to prevent cancers from escaping therapy.
