title: In vivo observation of pulmonary micrometastasis of colon cancer in normal rats.
abstract: The initial kinetics of cancer cell metastasis to organs requires investigation to establish an effective strategy against malignant disease. In vivo observation of pulmonary micrometastasis at an extremely early stage is of particular importance, and it is desirable from a clinical perspective to use an animal model with a normal immune system. RCN-9 cells labeled with green fluorescent protein were injected into the liver parenchyma of Fischer F344 male rats and the lungs were observed using real-time confocal laser scanning microscopy from 3 to 10 weeks after injection. Metastasis at the single cell level was observed throughout this period, but the number of pulmonary micrometastases did not increase significantly with time. The largest metastasis was 300 mum in diameter, and the mean size of the metastases did not increase with time. There were two types of micrometastases in terms of shape: round and linear metastases, with the latter resembling the pulmonary microvasculature. The precise location of each pulmonary micrometastasis was revealed by acridine orange infusion. We could observe a single cancer cell and a small cancer mass in endothelial and interstitial locations in vivo, and we found proliferating cancer cells both inside and outside of microvessels. Most of the pulmonary micrometastases stayed dormant as a single cell or a cancer mass of less than 100 microm in diameter until 10 weeks after cancer-cell injection into the liver.
authors: Graduate School of Comprehensive Human Sciences, Department of Respiratory Surgery, University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan.
authors: Kesato
authors: K
authors: Iguchi
authors: Gan
authors: G
authors: Oh
authors: Keiko
authors: K
authors: Ookawa
authors: Kenichi
authors: K
authors: Yanagi
authors: Mitsuaki
authors: M
authors: Sakai
authors: Tatsuo
authors: T
authors: Yamamoto
authors: Shigemi
authors: S
authors: Ishikawa
authors: Masataka
authors: M
authors: Onizuka
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D003110:Colonic Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D018450:Disease Progression; D049452:Green Fluorescent Proteins / Q000096:biosynthesis / Q000235:genetics; D008114:Liver Neoplasms, Experimental / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D008175:Lung Neoplasms / Q000235:genetics / Q000378:metabolism / Q000556:secondary*; D008297:Male; D018613:Microscopy, Confocal; D051381:Rats; D011916:Rats, Inbred F344; D013194:Staining and Labeling / Q000379:methods; D013997:Time Factors; D014162:Transfection
chemical_list: C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins