A novel bone morphogenetic protein signaling in heterotypic cell interactions in prostate cancer

Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, California 90033, USA.
Cancer Research (Impact Factor: 9.28). 02/2008; 68(1):198-205. DOI: 10.1158/0008-5472.CAN-07-5074
Source: PubMed

ABSTRACT We examined the effect of the extracellular bone morphogenetic protein (BMP) 2 and 7, which are up-regulated in the prostate adenocarcinomas of the conditional Pten deletion mouse model, on primary cultures of cancer-associated fibroblasts (CAF) derived from these tumors. In the CAF, we show that BMP2 or BMP7, but not transforming growth factor beta-1, can strikingly stimulate secretion of stromal cell-derived factor-1 (SDF-1), also known as CXCL12. The CAF cells express type I and type II BMP receptors as well as the receptor for SDF-1, CXCR4. SDF-1 activation is associated with BMP-induced Smad phosphorylation, and the stimulatory effect is blocked by BMP antagonist, noggin. The findings that BMP treatment can increase SDF-1 pre-mRNA levels in a time-dependent manner and actinomycin D treatment can abolish stimulatory effect of BMP suggest a transcriptional modulation of SDF-1 by BMP signaling. Using a human microvascular endothelial cell line, we show that SDF-1 present in the conditioned medium from the stimulated CAF can significantly induce tube formation, an effect relating to angiogenic function. Furthermore, we found that BMP2 can also protect the CAF from serum starvation-induced apoptosis independent of SDF-1, implying that BMP may induce other factors to sustain the survival of these cells. In short, this report establishes a novel BMP-SDF-1 axis in the prostate tumor along with a new prosurvival effect of BMP that when considered together with our previously described oncogenic properties of BMP indicate a circuitry for heterotypic cell interactions potentially critical in prostate cancer.

  • [Show abstract] [Hide abstract]
    ABSTRACT: Zusammenfassung Zahlreiche Erkenntnisse in der Prostatakarzinomforschung basieren auf Zellkulturergebnissen. Neuere genomische Untersuchungen zeigen jedoch, dass verwendete permanente Prostatakarzinomzelllinien sich deutlich von dem klinisch relevanten, primären Prostatakarzinom unterscheiden und damit die Übertragbarkeit dieser Zellkulturergebnisse auf die Klinik nur bedingt gegeben ist. Das Arbeiten mit Primärzellkulturen aus Gewebestückchen von Prostatektomiepräparaten bietet eine sehr gute Alternative, doch die Etablierung von Primärkulturen gestaltet sich schwierig und recht aufwändig. In dieser Arbeit wurde ein Primärzellkulturmodell mit einem Invasionssystem kombiniert. Hiermit gelang es nicht nur invasiv wachsende Zellpopulationen aus Primärkulturen zu selektionieren, sondern auch diese Zellen in einem 3D-Modell unter der Ausbildung von Sphäroiden weiter zu kultivieren. Zur Charakterisierung dieser Zellpopulation haben wir vergleichende genomische Hybridisierungen durchgeführt, die zahlreiche genetische Alterationen aufzeigen. Das hier dargestellte Modell ermöglicht es erstmalig, invasive Zellklone aus primärem Prostatakarzinomgewebe zu gewinnen und durch Kultivierung für weitere Untersuchungen zu verwenden.
    Der Urologe 09/2008; 47(9):1199-1204. DOI:10.1007/s00120-008-1835-x
  • [Show abstract] [Hide abstract]
    ABSTRACT: Much prostate cancer research is based on cell culture results. Recent genomic studies found major differences between primary prostate cancer tissue and established prostate cancer cell lines, which calls into question the clinical relevance of study results based on cell cultures.Using primary cultures of prostate cancer cells from prostatectomy specimens seems to be a reasonable solution, but primary cell cultures are much more difficult to establish. In this study, a primary cell culture model was combined with an invasion assay. With this combination it was possible not only to select invasive cell clones from the primary culture but also to culture these cells in a three-dimensional model, forming spheroids. A further characterization of this cell population was done by comparative genomic hybridization, showing numerous genetic alterations. The presented cell culture model offers, for the first time, an opportunity to isolate invasive growing cells from primary prostate cancer tissue and cultivate these cells for further analyses.
    Der Urologe 10/2008; 47(9):1199-204.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: CXCR4, a G-protein-coupled receptor of CXCL12/stromal cell-derived factor-1alpha, mediates a wide range of physiological and pathological processes, including the targeted metastasis of cancer cells. CXCR4 has been shown to homo-oligomerize in several experimental systems. However, it remains unclear with which domains CXCR4 interacts homotypically, and whether it dimerizes or forms a higher-order complex. To address these issues, we used bioluminescent resonance energy transfer and bimolecular fluorescence complementation analyses to measure the homotypic interactions of CXCR4 in living cells. Both assays indicated that CXCR4 interacts homotypically, which is consistent with previous studies. By studying CXCR4 mutants lacking various domains, we found that multiple transmembrane domains probably serve as potential molecular interaction surfaces for oligomerization. The relative contribution of the amino- or carboxy-termini to oligomerization was small. To differentiate between a dimer and a multimer consisting of more than two molecules, bioluminescent resonance energy transfer-bimolecular fluorescence complementation analysis was conducted. It revealed that CXCR4 engages in higher-order oligomerization in a ligand-independent fashion. This is the first report providing direct experimental evidence for the higher-order multimerization of CXCR4 in vivo. We hypothesize that CXCR4 distributes to the cell surface as a multimer, in order to effectively sense, with increased avidity, the chemotaxis-inducing ligand in the microenvironment. Studying the structure and function of the oligomeric state of CXCR4 may lead us to develop novel CXCR4 inhibitors that disassemble the molecular cluster of CXCR4.
    Cancer Science 11/2008; 100(1):95-102. DOI:10.1111/j.1349-7006.2008.00997.x