Global secretome analysis identifies novel mediators of bone metastasis
Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA. Cell Research
(Impact Factor: 12.41).
06/2012; 22(9):1339-55. DOI: 10.1038/cr.2012.89
Bone is the one of the most common sites of distant metastasis of solid tumors. Secreted proteins are known to influence pathological interactions between metastatic cancer cells and the bone stroma. To comprehensively profile secreted proteins associated with bone metastasis, we used quantitative and non-quantitative mass spectrometry to globally analyze the secretomes of nine cell lines of varying bone metastatic ability from multiple species and cancer types. By comparing the secretomes of parental cells and their bone metastatic derivatives, we identified the secreted proteins that were uniquely associated with bone metastasis in these cell lines. We then incorporated bioinformatic analyses of large clinical metastasis datasets to obtain a list of candidate novel bone metastasis proteins of several functional classes that were strongly associated with both clinical and experimental bone metastasis. Functional validation of selected proteins indicated that in vivo bone metastasis can be promoted by high expression of (1) the salivary cystatins CST1, CST2, and CST4; (2) the plasminogen activators PLAT and PLAU; or (3) the collagen functionality proteins PLOD2 and COL6A1. Overall, our study has uncovered several new secreted mediators of bone metastasis and therefore demonstrated that secretome analysis is a powerful method for identification of novel biomarkers and candidate therapeutic targets.
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Available from: Jayde E Ruelcke
- "A recent quantitative proteomics analysis of secreted proteins derived from cell lines with varying bone metastasis attributes derived from different cancers, combined with analysis of large clinical metastasis datasets, identified 7 genes (cystatins CST1, CST2 and CST3; plasminogen activators PLAT and PLAU; and collagen functionality proteins PLOD2 and COL6A1) as novel mediators of bone metastasis (54). Interestingly, individual knockdown of each gene did not block bone metastasis, however combined over expression of genes from the same functional group increased bone tumour burden (54). Notably, cavin-1 expression affected each of these functional groups. "
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ABSTRACT: BackgroundTumour-derived extracellular vesicles (EVs) play a role in tumour progression; however, the spectrum of molecular mechanisms regulating EV secretion and cargo selection remain to be fully elucidated. We have reported that cavin-1 expression in prostate cancer PC3 cells reduced the abundance of a subset of EV proteins, concomitant with reduced xenograft tumour growth and metastasis.MethodsWe examined the functional outcomes and mechanisms of cavin-1 expression on PC3-derived EVs (PC3-EVs).ResultsPC3-EVs were internalized by osteoclast precursor RAW264.7 cells and primary human osteoblasts (hOBs) in vitro, stimulating osteoclastogenesis 37-fold and hOB proliferation 1.5-fold, respectively. Strikin
gly, EVs derived from cavin-1-expressing PC3 cells (cavin-1-PC3-EVs) failed to induce multinucleate osteoblasts or hOB proliferation. Cavin-1 was not detected in EVs, indicating an indirect mechanism of action. EV morphology, size and quantity were also not affected by cavin-1 expression, suggesting that cavin-1 modulated EV cargo recruitment rather than release. While cavin-1-EVs had no osteoclastogenic function, they were internalized by RAW264.7 cells but at a reduced efficiency compared to control EVs. EV surface proteins are required for internalization of PC3-EVs by RAW264.7 cells, as proteinase K treatment abolished uptake of both control and cavin-1-PC3-EVs. Removal of sialic acid modifications by neuraminidase treatment increased the amount of control PC3-EVs internalized by RAW264.7 cells, without affecting cavin-1-PC3-EVs. This suggests that cavin-1 expression altered the glycosylation modifications on PC3-EV surface. Finally, cavin-1 expression did not affect EV in vivo tissue targeting as both control and cavin-1-PC3-EVs were predominantly retained in the lung and bone 24 hours after injection into mice.DiscussionTaken together, our results reveal a novel pathway for EV cargo sorting, and highlight the potential of utilizing cavin-1-mediated pathways to attenuate metastatic prostate cancer.
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- "For instance, reduction of GATA6 and/or HOPX led to increased expression of IL1B, IL11, and EREG, which encode for secreted factors associated with organotropic metastasis (Bos et al., 2009; Gupta et al., 2007; Kang et al., 2003). Vascular and ECM remodeling genes (VEGFA and PLAU) that promote metastatic progression (Blanco et al., 2012; Weis et al., 2004) were also activated. Some of the described transcriptional changes were observed in other ADC cell lines, with KRT6A/B induction being the most consistent response (Figures S7D and S7E). "
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ABSTRACT: Molecular programs that mediate normal cell differentiation are required for oncogenesis and tumor cell survival in certain cancers. How cell-lineage-restricted genes specifically influence metastasis is poorly defined. In lung cancers, we uncovered a transcriptional program that is preferentially associated with distal airway epithelial differentiation and lung adenocarcinoma (ADC) progression. This program is regulated in part by the lineage transcription factors GATA6 and HOPX. These factors can cooperatively limit the metastatic competence of ADC cells, by modulating overlapping alveolar differentiation and invasogenic target genes. Thus, GATA6 and HOPX are critical nodes in a lineage-selective pathway that directly links effectors of airway epithelial specification to the inhibition of metastasis in the lung ADC subtype.
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ABSTRACT: Secreted proteins play essential roles in every step of cancer metastasis, while the identities and functions of those that contribute to tissue-specific metastasis are largely uncharacterized. Two articles in Cell Research report the discovery and functional analyses of novel secreted proteins that are biologically and clinically relevant to bone metastasis. The combinatory approaches represented here, together with advances in related technology, will promise a better understanding of the cancer secretome.
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