This is depicted to the right where the disseminated cells
are able to home to all three organs.
But it is unable to survive in the kidneys and in the bone it will survive but
not proliferate.
In the liver, however, the cancer cell is able to establish a metastasis
because the micro-environment is conducive to its proliferation.
Thus this reflects the well known seed and soil hypothesis where,
in order to survive and grow, a seed must fall on good soil.
The seed and soil hypothesis is a very important one in the metastasis field.
There are still many unknowns in this area and
this is a major hypothesis that many researchers adhere to and try to prove.
Thus the remainder of this lecture will be taught with this hypothesis in mind.
This top quote reflects the main point of the hypothesis.
When a plant goes to seed, its seeds are carried in all directions.
But they can only live and grow if they fall on congenial soil.
In this analogy,
the seed is the disseminated cell that has reached the circulation.
Here, like a seed can be carried in all directions by the wind,
the cell may travel to many sites around the body by the blood and the lymph.
Where it lands, the soil, is any of these sites in the body and
is ultimately the organ site of the metastasis.
The makeup of this site, the soil, consists
of the cell types within that organ and their surrounding micro environment.
This can be the extracellular matrix and any cytokines or
secreted molecules that are present for the seed, or the cell, to interact with.
Ultimately, this soil is either permissive or restrictive for the growth of the seed.
And this is determined by the different factors in that organ site,
since these will vary, depending on which organ the cancer cell landed.