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Tagged tumor cells reveal regulatory steps during earliest
stages of tumor progression and micrometastasis
L.A. Culp1, W-C. Lin1,2 and N.R. Kleinman1,3
1Department of Molecular Biology and Microbiology,
Case Western Reserve University, School of Medicine, Cleveland,
USA, 2Institute of Biomedical Sciences, Academia Sinica and Clinical
Cancer Center, National Health Research Institutes, Taipei, Taiwan,
Republic of China and 3Animal Resource Center, Case Western Reserve
University, School of Medicine, Cleveland, USA
Offprint requests to: Dr.
Lloyd A. Culp, Department of Molecular Biology and Microbiology,
Case Western Reserve University, School of Medicine, Cleveland,
OH 44106, USA
Summary. Histochemical
marker genes were used to "tag" mouse fibrosarcoma or
human neuroblastoma cells, providing a better understanding of
their subsequent progression and metastasis mechanisms in nude
mice. Micrometastases in the lung were initiated from clusters
of 2-6 cells rather than single cells in most cases; tumor cells
were also visualized binding to the endothelium of small blood
vessels to initiate these micrometastases. Shortterm, these mechanisms
relied heavily on fluidity of cell surface proteins, rather than
nuclear events. Micrometastases in some organs were transient
and never became established. Angiogenesis was visualized in both
primary tumor systems via "fixation" of the animal's
circulation; very small micro-vessels were growing toward the
primary tumor as soon as 48-72 hours post-injection. Marker genes
were also valuable for quantitating genetic instability of specific
tumor cell populations and potential gene regulatory mechanisms
operating in specific organ sites. These latter studies have direct
relevance to the significance of N-myc oncogene amplification
in neuroblastoma during progression and CD44 gene plasticity of
expression in fibrosarcoma during metastasis. Marker gene-tagged
single tumor cells can now be analyzed for gene regulatory events
in virtually any organ and in combination with laser capture microdissection
and other high-resolution methodologies, providing insight into
the very earliest gene-regulatory events during micrometastasis.
Histol. Histopathol. 14, 879-886
Key words: Histochemical
marker gene, Tumor progression, Micrometastasis, Angiogenesis,
Gene regulation
DOI: 10.14670/HH-14.879
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