Slime mold and cancer
Some cancer cells merge together to form a large bag of cytoplasm enclosing a bunch of nuclei (multinucleated giant cells). In many cases, it is these multinucleated giant cells that give rise to resistant metastatic cancer cells.
This phenomenon is also found in the amoeba cells of slime molds that join together to form a swarming one-cell organism of thousands of nuclei (1, 2). In fact, many of the features of an amoeba cell of a slime mold organism (such as migration, budding of daughter cells, learning to avoid toxins, etc) are the same as those of metastatic cancer cells.
In this article, I will describe both entities - multinucleated cells in cancer and multinucleated cells in amoeba (or slime mold).
Giant cancer cells
Some cancers are identifiable because of the presence of giant, multinucleated cells. For example, Hodgkin's lymphoma is only diagnosed when the typical Reed-Sternberg cell is seen. This cell can be 10-15 times the size of a small B-lymphocyte in the lymph nodes. These giant cells - with their giant nuclei that look like owl's eyes - are formed when two daughter cells separate (or almost separate) and then decide to join together again (3).
Other cancers also have multinucleated giant cells (4). For example, such cells are found in ovarian cancer (4, 5, 6), breast cancer (7), colorectal cancer (8) glioblastoma (9), lung cancer (10), and metastatic prostate cancer (11, 12).
What does this have to do with slime molds?
When food is plentiful, slime mold cells exist as typical one-cell organisms with a singe nucleus. However, remove their steady supply of food, expose them to light, drown them in toxins, and those happy-go-lucky small cells converge together and fuse, like a bunch of rain drops coalescing into a puddle (13-14).
- As a single-nucleus cell, a Physarum amoeba has multiple ways of protection from hostile environments, from migration, to the production of spores, to encasing itself into an amoebic cyst.
- Not only that, this "simple" amoeba cell can join others and become a large plasmodium, an enormous one cell organism that now has tons of nuclei. This 'bag" of nuclei develops pseudopodia that help the plasmodium move at the rate of 4 cm/hour to find new food sources.
- As a plasmodium, a Physarum organism can also construct a smart network of cytoplasmic tubules or veins (see image below), like an outward reaching circulatory system. This network allows the cytoplasm within the veins to stream to some areas and pull away from others, controlling the flow of information and nutrients.
- One experiment showed that the network developed by the plasmodium mimicked that of the Tokyo railway system .
- When the plasmodium organism is threatened because of lack of food, it develops specialized stalks and heads that have spores within them. These spores spew out from the heads to build new life cycles in other locations.
This is one resourceful cell! (albeit with multiple heads, hence the name "Physarum polycephalum").
What about multinucleated giant cancer cells?
Compare the slime mold to multinucleated giant cancer cells.
- Cancer cells - particularly those that have been treated with chemo/radiation - fuse together to produce multinucleated giant cells (18, 19)
- Cancer cells that are metastatic develop amoeboid characteristics that allow them to migrate to new locations (20)
- Multinucleated giant cells can pinch off daughter cells that continue the life cycle of the original cancer cells (21, 22, 23)
- Multinucleated giant cells habituate to toxins and learn to adapt to those, making those cancer cells more resistant to chemotherapy (11-12, 20-23).
In fact, those giant monster cells show the ability to propagate and develop increasing resistance, producing metastatic cancer in animal models (12).
Teaching and propagating survival techniques
To add insult to injury, giant multinucleated cells (both of slime mold and cancer cells) have the ability to teach susceptible cells any tricks that they have learned.
For example, slime mold cells that have been exposed to a repellent will transfer that learning to other cells upon fusing with them (1). Similarly, cancer cells - particularly metastatic ones - transfer the propensity to proliferation from the giant cell to susceptible neighboring cells, through cytoplasmic tunnels (4).
Multinucleated giant cells - from slime mold plasmodia to cancer cells - have a lot of tools in their arsenal to ensure propagation and survival.
Cancer cells going back to their embryonal origins
In fact, the life cycle of cancer cells have been likened to that of evolutionary embryonal cells that are able to withstand environmental threats (24).
Cancer cells behave like embryonal cells that divide into haploid cells, fuse asexually, form clumps of tumor cells - similar to a blastocyst of an embryo - and then produce a vascularized tumor mass.
As has been stated, the development of giant multinucleated cancer cells in cancer is bad news (4-12). These cells are hardy, fertile, resourceful, wily, and powerful. In experiments with nude mice, it only took one of those giant multinucleated giant cells (ONE!) to induce the development of multiple tumors (25).
The one-line conclusion?
Cancer cells that portend a bad prognosis are trying to survive an unsupportive environment, just like an ancestral species, the slime mold.
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