Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Review Article
  • Published:

Illuminating the metastatic process

Nature Reviews Cancer volume 7, pages 737–749 (2007)Cite this article

Key Points

  • Metastasis is the spread of cancer from its site of origin and subsequent colonization of distant organs. Until recently, studying the details of this process has been difficult owing to the limited number of cells involved and the inaccessibility of the relevant anatomical sites.

  • Optical imaging enables the process of metastasis to be observed and studied directly. Resolution can vary from the level of whole tissues down to sub-cellular structures depending on the imaging method.

  • In addition to detecting tumour cells, imaging can provide information about cell movement, interactions between cells, the activity of proteins or signalling pathways, and blood and lymphatic flow.

  • Very few cells within primary tumours are motile, and these move rapidly with an amoeboid morphology.

  • Metastatic cells are better at entering the blood vessels and withstanding shear stress than their non-metastatic counterparts.

  • Cells lodge in capillaries by various mechanisms, including physical constraint, aggregation with platelets and active interactions with the endothelium.

  • Apoptosis of tumour cells shortly after arriving at secondary sites is a major source of inefficiency in the metastatic process.

  • Certain tumour types preferentially metastasize to particular secondary sites, and the distribution of metastases cannot solely be accounted for by the pattern of blood flow. The molecular basis of this phenomenon is not well understood.

  • Imaging can be used in the preclinical evaluation of drugs that target steps in the metastatic process.

Abstract

Until recently most studies of metastasis only measured the end point of the process — macroscopic metastases. Although these studies have provided much useful information, the details of the metastatic process remain somewhat mysterious owing to difficulties in studying cell behaviour with high spatial and temporal resolution in vivo. The use of luminescent and fluorescent proteins and developments in optical imaging technology have enabled the direct observation of cancer cells spreading from their site of origin and arriving at secondary sites. This Review will describe recent advances in our understanding of the different steps of metastasis gained from cellular resolution imaging, and how these techniques can be used in preclinical drug evaluation.

This is a preview of subscription content, access via your institution

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Uses of optical imaging in studying the metastatic process.
Figure 2: Directed movement of cancer cells towards blood vessels.
Figure 3: Amoeboid cancer cell invasion in vivo.

Similar content being viewed by others

References

  1. Chambers, A. F., Groom, A. C. & MacDonald, I. C. Dissemination and growth of cancer cells in metastatic sites. Nature Rev. Cancer 2, 563–572 (2002).

    Article  CAS  Google Scholar 

  2. Weiss, L. Metastatic inefficiency. Adv. Cancer Res. 54, 159–211 (1990).

    Article  CAS  PubMed  Google Scholar 

  3. Wong, C. W. et al. Apoptosis: an early event in metastatic inefficiency. Cancer Res. 61, 333–338 (2001).

    CAS  PubMed  Google Scholar 

  4. Wood, S. Jr. Pathogenesis of metastasis formation observed in vivo in the rabbit ear chamber. AMA Arch. Pathol. 66, 550–568 (1958). Pioneering work imaging the behaviour of metastatic cancer cells in the rabbit ear; still holds up even after almost 50 years.

    PubMed  Google Scholar 

  5. Virchow, R. Uber bewegliche thierische Zellen. Arch. Path. Anat. 28, 237–240 (1863).

    Article  Google Scholar 

  6. Contag, C. H., Jenkins, D., Contag, P. R. & Negrin, R. S. Use of reporter genes for optical measurements of neoplastic disease in vivo. Neoplasia 2, 41–52 (2000).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  7. Hoffman, R. M. The multiple uses of fluorescent proteins to visualize cancer in vivo. Nature Rev. Cancer 5, 796–806 (2005). Good review article of how fluorescent proteins have been exploited for the study of cancer in vivo.

    Article  CAS  Google Scholar 

  8. Shaner, N. C., Steinbach, P. A. & Tsien, R. Y. A guide to choosing fluorescent proteins. Nature Methods 2, 905–909 (2005).

    Article  CAS  PubMed  Google Scholar 

  9. Condeelis, J. & Segall, J. E. Intravital imaging of cell movement in tumours. Nature Rev. Cancer 3, 921–930 (2003).

    Article  CAS  Google Scholar 

  10. Friedl, P. & Wolf, K. Tumour-cell invasion and migration: diversity and escape mechanisms. Nature Rev. Cancer 3, 362–374 (2003).

    Article  CAS  Google Scholar 

  11. Wang, W. et al. The activity status of cofilin is directly related to invasion, intravasation, and metastasis of mammary tumors. J. Cell Biol. 173, 395–404 (2006).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  12. Kurisu, S., Suetsugu, S., Yamazaki, D., Yamaguchi, H. & Takenawa, T. Rac-WAVE2 signaling is involved in the invasive and metastatic phenotypes of murine melanoma cells. Oncogene 24, 1309–1319 (2005).

    Article  CAS  PubMed  Google Scholar 

  13. Wang, W. et al. Identification and testing of a gene expression signature of invasive carcinoma cells within primary mammary tumors. Cancer Res. 64, 8585–8594 (2004).

    Article  CAS  PubMed  Google Scholar 

  14. Flesken-Nikitin, A., Williams, R. M., Zipfel, W. R., Webb, W. W. & Nikitin, A. Y. Use of multiphoton imaging for studying cell migration in the mouse. Methods Mol. Biol. 294, 335–345 (2005).

    PubMed  Google Scholar 

  15. Zipfel, W. R., Williams, R. M. & Webb, W. W. Nonlinear magic: multiphoton microscopy in the biosciences. Nature Biotechnol. 21, 1369–1377 (2003).

    Article  CAS  Google Scholar 

  16. Wyckoff, J. B., Jones, J. G., Condeelis, J. S. & Segall, J. E. A critical step in metastasis: in vivo analysis of intravasation at the primary tumor. Cancer Res. 60, 2504–2511 (2000). One of the first studies to directly observe differences in motility and interactions with blood vessels between metastatic and non-metastatic cells.

    CAS  PubMed  Google Scholar 

  17. Geiger, B., Bershadsky, A., Pankov, R. & Yamada, K. M. Transmembrane crosstalk between the extracellular matrix–cytoskeleton crosstalk. Nature Rev. Mol. Cell Biol. 2, 793–805 (2001).

    Article  CAS  Google Scholar 

  18. Provenzano, P. P. et al. Collagen reorganization at the tumor-stromal interface facilitates local invasion. BMC Med. 4, 38 (2006).

    Article  PubMed  PubMed Central  CAS  Google Scholar 

  19. Wyckoff, J. B., Pinner, S. E., Gschmeissner, S., Condeelis, J. S. & Sahai, E. ROCK- and myosin-dependent matrix deformation enables protease-independent tumor-cell invasion in vivo. Curr. Biol. 16, 1515–1523 (2006). Analysis of the effects of anti-invasion drugs on cancer cell motility and acto–myosin organization in vivo.

    Article  CAS  PubMed  Google Scholar 

  20. Itoh, K. et al. An essential part for Rho-associated kinase in the transcellular invasion of tumor cells. Nature Med. 5, 221–225 (1999).

    Article  CAS  PubMed  Google Scholar 

  21. Wolf, K. et al. Compensation mechanism in tumor cell migration: mesenchymal-amoeboid transition after blocking of pericellular proteolysis. J. Cell Biol. 160, 267–277 (2003). Elegant study demonstrating how the plasticity of cancer cell movement can negate the efficacy of anti-invasion drugs.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  22. Jiang, T. et al. Tumor imaging by means of proteolytic activation of cell-penetrating peptides. Proc. Natl Acad. Sci. USA 101, 17867–17872 (2004).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  23. Bremer, C., Tung, C. H. & Weissleder, R. In vivo molecular target assessment of matrix metalloproteinase inhibition. Nature Med. 7, 743–748 (2001).

    Article  CAS  PubMed  Google Scholar 

  24. Weissleder, R., Tung, C. H., Mahmood, U. & Bogdanov, A., Jr. In vivo imaging of tumors with protease-activated near-infrared fluorescent probes. Nature Biotechnol. 17, 375–378 (1999). Technically impressive study describing the development and use of a fluorescent probe that is activated in response to tumour-associated protease activity.

    Article  CAS  Google Scholar 

  25. Tung, C. H., Mahmood, U., Bredow, S. & Weissleder, R. In vivo imaging of proteolytic enzyme activity using a novel molecular reporter. Cancer Res. 60, 4953–4958 (2000).

    CAS  PubMed  Google Scholar 

  26. Wood, S. Jr. Mechanisms of establishment of tumor metastases. Pathobiol. Annu. 1, 281–308 (1971).

    PubMed  Google Scholar 

  27. Sahai, E. Mechanisms of cancer cell invasion. Curr. Opin. Genet. Dev. 15, 87–96 (2005).

    Article  CAS  PubMed  Google Scholar 

  28. Sahai, E. & Marshall, C. J. Differing modes of tumour cell invasion have distinct requirements for Rho/ROCK signalling and extracellular proteolysis. Nature Cell Biol. 5, 711–719 (2003).

    Article  CAS  PubMed  Google Scholar 

  29. Wang, H. R. et al. Regulation of cell polarity and protrusion formation by targeting RhoA for degradation. Science 302, 1775–1779 (2003).

    Article  CAS  PubMed  Google Scholar 

  30. Sahai, E., Garcia-Medina, R., Pouyssegur, J. & Vial, E. Smurf1 regulates tumor cell plasticity and motility through degradation of RhoA leading to localized inhibition of contractility. J. Cell Biol. 176, 35–42 (2007).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  31. DiCostanzo, D., Rosen, P. P., Gareen, I., Franklin, S. & Lesser, M. Prognosis in infiltrating lobular carcinoma. An analysis of “classical” and variant tumors. Am. J. Surg. Pathol. 14, 12–23 (1990).

    Article  CAS  PubMed  Google Scholar 

  32. Yamamoto, E., Kohama, G., Sunakawa, H., Iwai, M. & Hiratsuka, H. Mode of invasion, bleomycin sensitivity, and clinical course in squamous cell carcinoma of the oral cavity. Cancer 51, 2175–2180 (1983).

    Article  CAS  PubMed  Google Scholar 

  33. Bremer, C. et al. Optical imaging of spontaneous breast tumors using protease sensing 'smart' optical probes. Invest. Radiol. 40, 321–327 (2005).

    Article  CAS  PubMed  Google Scholar 

  34. Ahmed, F. et al. GFP expression in the mammary gland for imaging of mammary tumor cells in transgenic mice. Cancer Res. 62, 7166–7169 (2002).

    CAS  PubMed  Google Scholar 

  35. Vooijs, M., Jonkers, J., Lyons, S. & Berns, A. Noninvasive imaging of spontaneous retinoblastoma pathway-dependent tumors in mice. Cancer Res. 62, 1862–1867 (2002).

    CAS  PubMed  Google Scholar 

  36. Sharpless, N. E. & Depinho, R. A. The mighty mouse: genetically engineered mouse models in cancer drug development. Nature Rev. Drug Discov. 5, 741–754 (2006).

    Article  CAS  Google Scholar 

  37. Drake, J. M., Gabriel, C. L. & Henry, M. D. Assessing tumor growth and distribution in a model of prostate cancer metastasis using bioluminescence imaging. Clin. Exp. Metastasis 22, 674–684 (2005).

    Article  PubMed  Google Scholar 

  38. Tassone, P. et al. A clinically relevant SCID-hu in vivo model of human multiple myeloma. Blood 106, 713–716 (2005).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  39. Berking, C. & Herlyn, M. Human skin reconstruct models: a new application for studies of melanocyte and melanoma biology. Histol. Histopathol. 16, 669–674 (2001).

    CAS  PubMed  Google Scholar 

  40. Wyckoff, J. et al. A paracrine loop between tumor cells and macrophages is required for tumor cell migration in mammary tumors. Cancer Res. 64, 7022–7029 (2004).

    Article  CAS  PubMed  Google Scholar 

  41. Wyckoff, J. B. et al. Direct visualization of macrophage-assisted tumor cell intravasation in mammary tumors. Cancer Res. 67, 2649–2656 (2007).

    Article  CAS  PubMed  Google Scholar 

  42. Goswami, S. et al. Macrophages promote the invasion of breast carcinoma cells via a colony-stimulating factor-1/epidermal growth factor paracrine loop. Cancer Res. 65, 5278–5283 (2005).

    Article  CAS  PubMed  Google Scholar 

  43. Lin, E. Y. et al. Progression to malignancy in the polyoma middle T oncoprotein mouse breast cancer model provides a reliable model for human diseases. Am. J. Pathol. 163, 2113–2126 (2003).

    Article  PubMed  PubMed Central  Google Scholar 

  44. Sahai, E. et al. Simultaneous imaging of GFP, CFP and collagen in tumors in vivo using multiphoton microscopy. BMC Biotechnol. 5, 14 (2005).

    Article  PubMed  PubMed Central  CAS  Google Scholar 

  45. Xue, C. et al. Epidermal growth factor receptor overexpression results in increased tumor cell motility in vivo coordinately with enhanced intravasation and metastasis. Cancer Res. 66, 192–197 (2006).

    Article  CAS  PubMed  Google Scholar 

  46. Li, C. Y. et al. Initial stages of tumor cell-induced angiogenesis: evaluation via skin window chambers in rodent models. J. Natl Cancer Inst. 92, 143–147 (2000).

    Article  CAS  PubMed  Google Scholar 

  47. Chang, Y. S. et al. Mosaic blood vessels in tumors: frequency of cancer cells in contact with flowing blood. Proc. Natl Acad. Sci. USA 97, 14608–14613 (2000). Provocative study suggesting that tumour cells can contribute directly to tumour vasculature.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  48. Hendrix, M. J. et al. Expression and functional significance of VE-cadherin in aggressive human melanoma cells: role in vasculogenic mimicry. Proc. Natl Acad. Sci. USA 98, 8018–8023 (2001).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  49. Dadiani, M. et al. Real-time imaging of lymphogenic metastasis in orthotopic human breast cancer. Cancer Res. 66, 8037–8041 (2006).

    Article  CAS  PubMed  Google Scholar 

  50. Hoshida, T. et al. Imaging steps of lymphatic metastasis reveals that vascular endothelial growth factor-C increases metastasis by increasing delivery of cancer cells to lymph nodes: therapeutic implications. Cancer Res. 66, 8065–8075 (2006).

    Article  CAS  PubMed  Google Scholar 

  51. Hagendoorn, J. et al. Onset of abnormal blood and lymphatic vessel function and interstitial hypertension in early stages of carcinogenesis. Cancer Res. 66, 3360–3364 (2006).

    Article  CAS  PubMed  Google Scholar 

  52. Carr, I. Lymphatic metastasis. Cancer Metastasis Rev. 2, 307–317 (1983).

    Article  CAS  PubMed  Google Scholar 

  53. Carr, J., Carr, I., Dreher, B. & Betts, K. Lymphatic metastasis: invasion of lymphatic vessels and efflux of tumour cells in the afferent popliteal lymph as seen in the Walker rat carcinoma. J. Pathol. 132, 287–305 (1980).

    Article  CAS  PubMed  Google Scholar 

  54. Shields, J. D. et al. Autologous chemotaxis as a mechanism of tumor cell homing to lymphatics via interstitial flow and autocrine CCR7 signaling. Cancer Cell 11, 526–538 (2007).

    Article  CAS  PubMed  Google Scholar 

  55. Isaka, N., Padera, T. P., Hagendoorn, J., Fukumura, D. & Jain, R. K. Peritumor lymphatics induced by vascular endothelial growth factor-C exhibit abnormal function. Cancer Res. 64, 4400–4404 (2004).

    Article  CAS  PubMed  Google Scholar 

  56. Alexandrakis, G. et al. Two-photon fluorescence correlation microscopy reveals the two-phase nature of transport in tumors. Nature Med. 10, 203–207 (2004).

    Article  CAS  PubMed  Google Scholar 

  57. Cameron, M. D. et al. Temporal progression of metastasis in lung: cell survival, dormancy, and location dependence of metastatic inefficiency. Cancer Res. 60, 2541–2546 (2000).

    CAS  PubMed  Google Scholar 

  58. Tarin, D. et al. Mechanisms of human tumor metastasis studied in patients with peritoneovenous shunts. Cancer Res. 44, 3584–3592 (1984).

    CAS  PubMed  Google Scholar 

  59. Ito, S. et al. Real-time observation of micrometastasis formation in the living mouse liver using a green fluorescent protein gene-tagged rat tongue carcinoma cell line. Int. J. Cancer 93, 212–217 (2001).

    Article  CAS  PubMed  Google Scholar 

  60. Naumov, G. N. et al. Cellular expression of green fluorescent protein, coupled with high-resolution in vivo videomicroscopy, to monitor steps in tumor metastasis. J. Cell Sci. 112, 1835–1842 (1999).

    Article  CAS  PubMed  Google Scholar 

  61. Im, J. H. et al. Coagulation facilitates tumor cell spreading in the pulmonary vasculature during early metastatic colony formation. Cancer Res. 64, 8613–8619 (2004).

    Article  CAS  PubMed  Google Scholar 

  62. Wang, H. et al. Tumor cell α3β1 integrin and vascular laminin-5 mediate pulmonary arrest and metastasis. J. Cell Biol. 164, 935–941 (2004).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  63. Tsuji, K. et al. Dual-color imaging of nuclear-cytoplasmic dynamics, viability, and proliferation of cancer cells in the portal vein area. Cancer Res. 66, 303–306 (2006).

    Article  CAS  PubMed  Google Scholar 

  64. Wong, C. W. et al. Intravascular location of breast cancer cells after spontaneous metastasis to the lung. Am. J. Pathol. 161, 749–753 (2002).

    Article  PubMed  PubMed Central  Google Scholar 

  65. Luzzi, K. J. et al. Multistep nature of metastatic inefficiency: dormancy of solitary cells after successful extravasation and limited survival of early micrometastases. Am. J. Pathol. 153, 865–873 (1998).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  66. Kaplan, R. N. et al. VEGFR1-positive haematopoietic bone marrow progenitors initiate the pre-metastatic niche. Nature 438, 820–827 (2005).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  67. Rafii, S. & Lyden, D. S100 chemokines mediate bookmarking of premetastatic niches. Nature Cell Biol. 8, 1321–1323 (2006).

    Article  CAS  PubMed  Google Scholar 

  68. Hiratsuka, S., Watanabe, A., Aburatani, H. & Maru, Y. Tumour-mediated upregulation of chemoattractants and recruitment of myeloid cells predetermines lung metastasis. Nature Cell Biol. 8, 1369–1375 (2006).

    Article  CAS  PubMed  Google Scholar 

  69. Donato, R. S100: a multigenic family of calcium-modulated proteins of the EF-hand type with intracellular and extracellular functional roles. Int. J. Biochem. Cell Biol. 33, 637–668 (2001).

    Article  CAS  PubMed  Google Scholar 

  70. Scherbarth, S. & Orr, F. W. Intravital videomicroscopic evidence for regulation of metastasis by the hepatic microvasculature: effects of interleukin-1a on metastasis and the location of B16F1 melanoma cell arrest. Cancer Res. 57, 4105–4110 (1997).

    CAS  PubMed  Google Scholar 

  71. Sipkins, D. A. et al. In vivo imaging of specialized bone marrow endothelial microdomains for tumour engraftment. Nature 435, 969–973 (2005). Elegant study that uses intravital confocal imaging of the skull to observe the homing of leukaemia cells to SDF1-expressing endothelium in the bone.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  72. Alencar, H., Mahmood, U., Kawano, Y., Hirata, T. & Weissleder, R. Novel multiwavelength microscopic scanner for mouse imaging. Neoplasia 7, 977–983 (2005).

    Article  PubMed  PubMed Central  Google Scholar 

  73. Fidler, I. J. Metastasis: guantitative analysis of distribution and fate of tumor embolilabeled with 125 I-5-iodo-2′-deoxyuridine. J. Natl Cancer Inst. 45, 773–782 (1970).

    CAS  PubMed  Google Scholar 

  74. Kim, J. W. et al. Rapid apoptosis in the pulmonary vasculature distinguishes non-metastatic from metastatic melanoma cells. Cancer Lett. 213, 203–212 (2004).

    Article  CAS  PubMed  Google Scholar 

  75. Varghese, H. J. et al. Activated ras regulates the proliferation/apoptosis balance and early survival of developing micrometastases. Cancer Res. 62, 887–891 (2002).

    CAS  PubMed  Google Scholar 

  76. Frisch, S. M. & Screaton, R. A. Anoikis mechanisms. Curr. Opin. Cell Biol. 13, 555–562 (2001).

    Article  CAS  PubMed  Google Scholar 

  77. Qiu, H. et al. Arrest of B16 melanoma cells in the mouse pulmonary microcirculation induces endothelial nitric oxide synthase-dependent nitric oxide release that is cytotoxic to the tumor cells. Am. J. Pathol. 162, 403–412 (2003).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  78. Bouvet, M. et al. In vivo color-coded imaging of the interaction of colon cancer cells and splenocytes in the formation of liver metastases. Cancer Res. 66, 11293–11297 (2006).

    Article  CAS  PubMed  Google Scholar 

  79. Pardoll, D. Does the immune system see tumors as foreign or self? Annu. Rev. Immunol. 21, 807–839 (2003).

    Article  CAS  PubMed  Google Scholar 

  80. Smyth, M. J., Godfrey, D. I. & Trapani, J. A. A fresh look at tumor immunosurveillance and immunotherapy. Nature Immunol. 2, 293–299 (2001).

    Article  CAS  Google Scholar 

  81. Boissonnas, A., Fetler, L., Zeelenberg, I. S., Hugues, S. & Amigorena, S. In vivo imaging of cytotoxic T cell infiltration and elimination of a solid tumor. J. Exp. Med. 204, 345–356 (2007). This study and the one below illustrate the potential of imaging interactions between tumour and immune cells.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  82. Mrass, P. et al. Random migration precedes stable target cell interactions of tumor-infiltrating T cells. J. Exp. Med. 203, 2749–2761 (2006).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  83. Bonnet, D. & Dick, J. E. Human acute myeloid leukemia is organized as a hierarchy that originates from a primitive hematopoietic cell. Nature Med. 3, 730–737 (1997).

    Article  CAS  PubMed  Google Scholar 

  84. Bjerkvig, R., Tysnes, B. B., Aboody, K. S., Najbauer, J. & Terzis, A. J. Opinion: the origin of the cancer stem cell: current controversies and new insights. Nature Rev. Cancer 5, 899–904 (2005).

    Article  CAS  Google Scholar 

  85. Amoh, Y. et al. Nestin-linked green fluorescent protein transgenic nude mouse for imaging human tumor angiogenesis. Cancer Res. 65, 5352–5357 (2005).

    Article  CAS  PubMed  Google Scholar 

  86. Ma, X., Robin, C., Ottersbach, K. & Dzierzak, E. The Ly-6A (Sca-1) GFP transgene is expressed in all adult mouse hematopoietic stem cells. Stem Cells 20, 514–521 (2002).

    Article  CAS  PubMed  Google Scholar 

  87. Montarras, D. et al. Direct isolation of satellite cells for skeletal muscle regeneration. Science 309, 2064–2067 (2005).

    Article  CAS  PubMed  Google Scholar 

  88. Naumov, G. N. et al. Persistence of solitary mammary carcinoma cells in a secondary site: a possible contributor to dormancy. Cancer Res. 62, 2162–2168 (2002).

    CAS  PubMed  Google Scholar 

  89. Naumov, G. N., MacDonald, I. C., Chambers, A. F. & Groom, A. C. Solitary cancer cells as a possible source of tumour dormancy? Semin. Cancer Biol. 11, 271–276 (2001).

    Article  CAS  PubMed  Google Scholar 

  90. Heyn, C. et al. In vivo MRI of cancer cell fate at the single-cell level in a mouse model of breast cancer metastasis to the brain. Magn. Reson. Med. 56, 1001–1010 (2006).

    Article  PubMed  Google Scholar 

  91. Paget, S. The distribution of secondary growths in cancer of the breast. Lancet 1, 571–573 (1889).

    Article  Google Scholar 

  92. Kang, Y. et al. Breast cancer bone metastasis mediated by the Smad tumor suppressor pathway. Proc. Natl Acad. Sci. USA 102, 13909–13914 (2005).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  93. Sloan, E. K. & Anderson, R. L. Genes involved in breast cancer metastasis to bone. Cell Mol. Life Sci. 59, 1491–1502 (2002).

    Article  CAS  PubMed  Google Scholar 

  94. Muller, A. et al. Involvement of chemokine receptors in breast cancer metastasis. Nature 410, 50–56 (2001).

    Article  CAS  PubMed  Google Scholar 

  95. El-Deiry, W. S., Sigman, C. C. & Kelloff, G. J. Imaging and oncologic drug development. J. Clin. Oncol. 24, 3261–3273 (2006).

    Article  CAS  PubMed  Google Scholar 

  96. Glory, E. & Murphy, R. F. Automated subcellular location determination and high-throughput microscopy. Dev. Cell 12, 7–16 (2007).

    Article  CAS  PubMed  Google Scholar 

  97. Wolff, M., Wiedenmann, J., Nienhaus, G. U., Valler, M. & Heilker, R. Novel fluorescent proteins for high-content screening. Drug Discov. Today 11, 1054–1060 (2006).

    Article  CAS  PubMed  Google Scholar 

  98. Bouvet, M. et al. Real-time optical imaging of primary tumor growth and multiple metastatic events in a pancreatic cancer orthotopic model. Cancer Res. 62, 1534–1540 (2002).

    CAS  PubMed  Google Scholar 

  99. Shah, K. & Weissleder, R. Molecular optical imaging: applications leading to the development of present day therapeutics. Neuro Rx 2, 215–225 (2005).

    Article  Google Scholar 

  100. Weissleder, R. Molecular imaging in cancer. Science 312, 1168–1171 (2006).

    Article  CAS  PubMed  Google Scholar 

  101. van der Pluijm, G. et al. Interference with the microenvironmental support impairs the de novo formation of bone metastases in vivo. Cancer Res. 65, 7682–7690 (2005).

    Article  CAS  PubMed  Google Scholar 

  102. Hoffman, R. M. Advantages of multi-color fluorescent proteins for whole-body and in vivo cellular imaging. J. Biomed. Opt. 10, 41202 (2005).

    Article  PubMed  CAS  Google Scholar 

  103. Montet, X., Ntziachristos, V., Grimm, J. & Weissleder, R. Tomographic fluorescence mapping of tumor targets. Cancer Res. 65, 6330–6336 (2005).

    Article  CAS  PubMed  Google Scholar 

  104. Dennis, M. S. et al. Imaging tumors with an albumin-binding Fab, a novel tumor-targeting agent. Cancer Res. 67, 254–261 (2007).

    Article  CAS  PubMed  Google Scholar 

  105. Jain, R. K., Tong, R. T. & Munn, L. L. Effect of vascular normalization by antiangiogenic therapy on interstitial hypertension, peritumor edema, and lymphatic metastasis: insights from a mathematical model. Cancer Res. 67, 2729–2735 (2007).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  106. Shah, K., Jacobs, A., Breakefield, X. O. & Weissleder, R. Molecular imaging of gene therapy for cancer. Gene Ther. 11, 1175–1187 (2004).

    Article  CAS  PubMed  Google Scholar 

  107. Uhrbom, L., Nerio, E. & Holland, E. C. Dissecting tumor maintenance requirements using bioluminescence imaging of cell proliferation in a mouse glioma model. Nature Med. 10, 1257–1260 (2004).

    Article  CAS  PubMed  Google Scholar 

  108. Wang, Y. et al. Noninvasive indirect imaging of vascular endothelial growth factor gene expression using bioluminescence imaging in living transgenic mice. Physiol. Genomics 24, 173–180 (2006).

    Article  PubMed  CAS  Google Scholar 

  109. Wang, W. & El-Deiry, W. S. Bioluminescent molecular imaging of endogenous and exogenous p53-mediated transcription in vitro and in vivo using an HCT116 human colon carcinoma xenograft model. Cancer Biol. Ther. 2, 196–202 (2003).

    Article  PubMed  Google Scholar 

  110. Messerli, S. M. et al. A novel method for imaging apoptosis using a caspase-1 near-infrared fluorescent probe. Neoplasia 6, 95–105 (2004).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  111. Schellenberger, E. A. et al. Optical imaging of apoptosis as a biomarker of tumor response to chemotherapy. Neoplasia 5, 187–192 (2003).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  112. Ilagan, R. et al. Imaging mitogen-activated protein kinase function in xenograft models of prostate cancer. Cancer Res. 66, 10778–10785 (2006).

    Article  CAS  PubMed  Google Scholar 

  113. Paulmurugan, R. & Gambhir, S. S. An intramolecular folding sensor for imaging estrogen receptor-ligand interactions. Proc. Natl Acad. Sci. USA 103, 15883–15888 (2006).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  114. Harada, H., Kizaka-Kondoh, S. & Hiraoka, M. Optical imaging of tumor hypoxia and evaluation of efficacy of a hypoxia-targeting drug in living animals. Mol. Imaging 4, 182–193 (2005).

    Article  PubMed  Google Scholar 

  115. Overall, C. M. & Kleifeld, O. Tumour microenvironment - opinion: validating matrix metalloproteinases as drug targets and anti-targets for cancer therapy. Nature Rev. Cancer 6, 227–239 (2006).

    Article  CAS  Google Scholar 

  116. Brown, E. et al. Dynamic imaging of collagen and its modulation in tumors in vivo using second-harmonic generation. Nature Med. 9, 796–800 (2003).

    Article  CAS  PubMed  Google Scholar 

  117. Brown, E. B. et al. In vivo measurement of gene expression, angiogenesis and physiological function in tumors using multiphoton laser scanning microscopy. Nature Med. 7, 864–868 (2001). Illustrates the many and complex types of measurements that can be made using multiphoton imaging.

    Article  CAS  PubMed  Google Scholar 

  118. Tozer, G. M. et al. Intravital imaging of tumour vascular networks using multi-photon fluorescence microscopy. Adv. Drug Deliv. Rev. 57, 135–152 (2005).

    Article  CAS  PubMed  Google Scholar 

  119. Tozer, G. M. et al. Mechanisms associated with tumor vascular shut-down induced by combretastatin A-4 phosphate: intravital microscopy and measurement of vascular permeability. Cancer Res. 61, 6413–6422 (2001).

    CAS  PubMed  Google Scholar 

  120. Montet, X. et al. Tomographic fluorescence imaging of tumor vascular volume in mice. Radiology 242, 751–758 (2007).

    Article  PubMed  Google Scholar 

  121. Serganova, I. et al. Molecular imaging of temporal dynamics and spatial heterogeneity of hypoxia-inducible factor-1 signal transduction activity in tumors in living mice. Cancer Res. 64, 6101–6108 (2004).

    Article  CAS  PubMed  Google Scholar 

  122. Tong, R. T. et al. Vascular normalization by vascular endothelial growth factor receptor 2 blockade induces a pressure gradient across the vasculature and improves drug penetration in tumors. Cancer Res. 64, 3731–3736 (2004).

    Article  CAS  PubMed  Google Scholar 

  123. Winkler, F. et al. Kinetics of vascular normalization by VEGFR2 blockade governs brain tumor response to radiation: role of oxygenation, angiopoietin-1, and matrix metalloproteinases. Cancer Cell 6, 553–563 (2004).

    CAS  PubMed  Google Scholar 

  124. Doubrovin, M., Serganova, I., Mayer-Kuckuk, P., Ponomarev, V. & Blasberg, R. G. Multimodality in vivo molecular-genetic imaging. Bioconjug. Chem. 15, 1376–1388 (2004).

    Article  CAS  PubMed  Google Scholar 

  125. Weissleder, R. & Ntziachristos, V. Shedding light onto live molecular targets. Nature Med. 9, 123–128 (2003).

    Article  CAS  PubMed  Google Scholar 

  126. Hanlon, E. B. et al. Prospects for in vivo Raman spectroscopy. Phys. Med. Biol. 45, R1–R59 (2000).

    Article  CAS  PubMed  Google Scholar 

  127. Baena, J. R. & Lendl, B. Raman spectroscopy in chemical bioanalysis. Curr. Opin. Chem. Biol. 8, 534–539 (2004).

    Article  CAS  PubMed  Google Scholar 

  128. Cheng, J. X., Jia, Y. K., Zheng, G. & Xie, X. S. Laser-scanning coherent anti-Stokes Raman scattering microscopy and applications to cell biology. Biophys. J. 83, 502–509 (2002).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  129. Shaner, N. C. et al. Improved monomeric red, orange and yellow fluorescent proteins derived from Discosoma sp. red fluorescent protein. Nature Biotechnol. 22, 1567–1572 (2004).

    Article  CAS  Google Scholar 

  130. Shah, K., Tang, Y., Breakefield, X. & Weissleder, R. Real-time imaging of TRAIL-induced apoptosis of glioma tumors in vivo. Oncogene 22, 6865–6872 (2003).

    Article  CAS  PubMed  Google Scholar 

  131. Zaheer, A. et al. In vivo near-infrared fluorescence imaging of osteoblastic activity. Nature Biotechnol. 19, 1148–1154 (2001).

    Article  CAS  Google Scholar 

  132. Frangioni, J. V. Self-illuminating quantum dots light the way. Nature Biotechnol. 24, 326–328 (2006).

    Article  CAS  Google Scholar 

  133. So, M. K., Xu, C., Loening, A. M., Gambhir, S. S. & Rao, J. Self-illuminating quantum dot conjugates for in vivo imaging. Nature Biotechnol. 24, 339–343 (2006).

    Article  CAS  Google Scholar 

  134. Montet, X., Montet-Abou, K., Reynolds, F., Weissleder, R. & Josephson, L. Nanoparticle imaging of integrins on tumor cells. Neoplasia 8, 214–222 (2006).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  135. Trepel, M., Arap, W. & Pasqualini, R. In vivo phage display and vascular heterogeneity: implications for targeted medicine. Curr. Opin. Chem. Biol. 6, 399–404 (2002).

    Article  CAS  PubMed  Google Scholar 

  136. Weissleder, R., Kelly, K., Sun, E. Y., Shtatland, T. & Josephson, L. Cell-specific targeting of nanoparticles by multivalent attachment of small molecules. Nature Biotechnol. 23, 1418–1423 (2005).

    Article  CAS  Google Scholar 

  137. Chen, X., Conti, P. S. & Moats, R. A. In vivo near-infrared fluorescence imaging of integrin alphavbeta3 in brain tumor xenografts. Cancer Res. 64, 8009–8014 (2004).

    Article  CAS  PubMed  Google Scholar 

  138. Cabantous, S., Terwilliger, T. C. & Waldo, G. S. Protein tagging and detection with engineered self-assembling fragments of green fluorescent protein. Nature Biotechnol. 23, 102–107 (2005).

    Article  CAS  Google Scholar 

  139. De, A. & Gambhir, S. S. Noninvasive imaging of protein-protein interactions from live cells and living subjects using bioluminescence resonance energy transfer. FASEB J. 19, 2017–2019 (2005).

    Article  CAS  PubMed  Google Scholar 

  140. Paulmurugan, R., Massoud, T. F., Huang, J. & Gambhir, S. S. Molecular imaging of drug-modulated protein-protein interactions in living subjects. Cancer Res. 64, 2113–2119 (2004).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  141. Bird, D. K. et al. Metabolic mapping of MCF10A human breast cells via multiphoton fluorescence lifetime imaging of the coenzyme NADH. Cancer Res. 65, 8766–8773 (2005).

    Article  CAS  PubMed  Google Scholar 

  142. Ntziachristos, V. & Chance, B. Probing physiology and molecular function using optical imaging: applications to breast cancer. Breast Cancer Res. 3, 41–46 (2001).

    Article  CAS  PubMed  Google Scholar 

  143. Zhang, H. F., Maslov, K., Stoica, G. & Wang, L. V. Functional photoacoustic microscopy for high-resolution and noninvasive in vivo imaging. Nature Biotechnol. 24, 848–851 (2006).

    Article  CAS  Google Scholar 

  144. Huang, D. et al. Optical coherence tomography. Science 254, 1178–1181 (1991).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  145. Fujimoto, J. G., Pitris, C., Boppart, S. A. & Brezinski, M. E. Optical coherence tomography: an emerging technology for biomedical imaging and optical biopsy. Neoplasia 2, 9–25 (2000).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  146. Zharov, V. P., Galanzha, E. I., Menyaev, Y. & Tuchin, V. V. In vivo high-speed imaging of individual cells in fast blood flow. J. Biomed. Opt. 11, 054034 (2006).

    Article  PubMed  Google Scholar 

  147. Zharov, V. P., Galanzha, E. I., Shashkov, E. V., Khlebtsov, N. G. & Tuchin, V. V. In vivo photoacoustic flow cytometry for monitoring of circulating single cancer cells and contrast agents. Opt. Lett. 31, 3623–3625 (2006).

    Article  PubMed  Google Scholar 

  148. Amoh, Y. et al. Visualization of nascent tumor angiogenesis in lung and liver metastasis by differential dual-color fluorescence imaging in nestin-linked-GFP mice. Clin. Exp. Metastasis 23, 315–322 (2006).

    Article  PubMed  Google Scholar 

Download references

Acknowledgements

I thank laboratory members and E. Brockbank for their comments and Cancer Research UK for funding.

Author information

Authors and Affiliations

  1. Cancer Research UK London Research Institute, 44 Lincoln's Inn Fields, London, WC2A 3PX, UK

    Erik Sahai

Authors
  1. Erik Sahai
    View author publications

    You can also search for this author in PubMed Google Scholar

Ethics declarations

Competing interests

The author declares no competing financial interests.

Supplementary information

Supplementary information S1 (movie)

Directed movement of cancer cells towards blood vessels. The margin of a tumour is imaged to reveal intrinsic collagen, autofluorescence, reflectance signals and green fluorescent protein (GFP)-expressing melanoma cells. In merged images melanoma cells (A375) are in green, collagen in blue, autofluorescence in red (revealing some phagocytic perivascular cells), and reflective material in white (revealing blood vessels and other non-tumour cells). Movie spans 32 minutes, frame is 600microns x 600microns. (AVI 8634 kb)

Supplementary information S2 (movie)

Amoeboid cancer cell invasion in vivo. The movement of green fluorescent protein (GFP)-expressing squamous cell carcinoma cells (A431) into collagen rich matrix surrounding a tumour is shown. Carcinoma cells are in green and collagen fibres are in red. Movie spans 20 minutes, frame is 150microns x 180microns. (AVI 216 kb)

Related links

Related links

FURTHER INFORMATION

Erik Sahai's homepage

Glossary

Intravasation

The entry of cells to the vasculature.

Extravasation

The exit of cells from the vasculature.

Intravital imaging

A generic term for imaging a living organism.

Multiphoton microscopy

This type of microscopy uses multiple longer wavelength photons (usually between 700–1,000 nm) to excite a fluorophore. Has the benefit that longer wavelengths penetrate tissue better to excite fluorophores and that fluorophore excitation only occurs at the focal point, thereby reducing spurious signals from outside the focal plane. These factors combine to greatly improve the depth of tissue that can be imaged using multiphoton laser scanning microscopy.

Confocal or laser scanning microscopy

Moves a focused point of laser light around the area or volume of interest and uses a 'pin-hole' to capture light specifically emitted from that point; this provides high-resolution in three dimensions.

Amoeboid motility

Motility characterized by high speeds, lack of stable polarity and a relatively amorphous cell shape. Frequently exhibited by cancer cells and leukocytes in vivo.

Acto–myosin interactions

Acto–myosin interactions exert force on the filamentous (F) actin cytoskeleton in cells.

Extracellular matrix

(ECM). A complex structural network of proteins and carbohydrates that surrounds cells and provides support and structure to tissues.

Second harmonic generation

Certain materials will emit light of exactly half the wavelength they are illuminated with. Collagen fibres are particularly suited for this phenomenon owing to large numbers of aligned α-helices.

Matrix metalloproteinases

(MMPs). Proteases that cleave ECM components.

Coherence

A physical technique that uses interference between a reference beam of light and light returning from the sample to determine how light is reflected by the sample.

Xenografts

Tumours that result from the injection or surgical implantation of tumour cells into either a syngeneic or immunocompromised animal.

Window chambers

Can be implanted in the skin of mice to enable imaging deeper inside the animal without the need for surgery at the time of imaging. They have the benefit that the same area can be repeatedly imaged over a number of days.

Shear stress

The physical force exerted on cells in the blood as a result of blood flow.

Sub-capsular region of lymph nodes

The area where lymph drained from the surrounding tissue enters the node.

Pre-metastatic niche

An area of tissue that is particularly suited for colonization by disseminating tumour cells.

S100 proteins

A family of Ca2+ EF-hand-binding proteins with a diverse range of intra- and extracellular functions. In particular, S100A8 and S100A9 have been implicated in modulation of immune cell migration.

Anoikis

Apoptosis triggered by lack of attachment to a substrate.

Vascular volume fraction

A measure of the volume of a tissue occupied by the vasculature.

Multi-modal imaging

Multi-modal imaging agents are designed such that they can be detected by more than one imaging technique (usually optical, computed tomography, magnetic resonance imaging and/or positron emission tomography), thereby making them more versatile.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Sahai, E. Illuminating the metastatic process. Nat Rev Cancer 7, 737–749 (2007). https://doi.org/10.1038/nrc2229

Download citation

  • Issue Date:

  • DOI: https://doi.org/10.1038/nrc2229

This article is cited by

Search

Advanced search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing