biology zoology blog tumours cells mothers

Can Tumours Become Mothers?

What a Strange Idea that tumours could become mothers!

I have mentioned in a previous blog that it was possible to create mosaic specimens from the fusion of embryonic cells of different donors at an early stage of development. Such mosaic animals are often also called “chimaeras” (after the Greek mythological beast that combined features of lion, goat, and dragon) and they can be extremely useful “tools” for the genetic researcher.

Take for instance cancerous growths, in other words, malignant structures: their cells although derived from normal tissue, have become abnormal and no longer contribute in a positive way to the tissue in which they grow. Features that further characterize these cells are a rapid and unregulated proliferation, which more than often can lead to the death of the individual harbouring these abnormal cells. If, however, the cell of a teratoma (a special kind of tumour) is introduced into an early mouse embryo, the resulting baby mouse is tumour-free and healthy in all respects. Has the introduced cancer cell been defeated or has it actually participated in the development of the mouse’s tissue and become a “good cell” again? One way to find out is to see whether the mouse has become a tumour cell/normal cell mosaic. If that is the case both cell types should be present in the healthy tissue of the body. And what was the result?

In the overwhelming number of cases, there is evidence that a mosaic did indeed develop, which shows that a tumour cell under certain conditions and the right environment so-to-speak, can revert back to normal. More than that, the “reformed” tumour cell is “pluripotent”, a big word for a big feature, because it means that it can give rise and build all kinds of body tissues. A very elegant demonstration of the cancer cell’s pluripotency comes from experiments with frogs. First, a group of American scientists obtained triploid (cells with three sets of chromosomes) early embryos by a technique of low-temperature treatment. Then kidney tumours were induced to grow in the triploid organism. Next, the triploid tumour cell nucleus was injected into a frog egg cell, whose own normal nucleus, haploid (with a single chromosome set) before and diploid (with a double chromosome set) after fertilization, had been removed or destroyed.

Those embryos that did continue to grow and develop after this nuclear transplantation experiment into the tadpole stage all had triploid and not haploid or diploid nuclei. That was the proof that the cancer cell nucleus alone had been responsible for cells to differentiate into all kinds of specialized cells of the various organs that the new frog needed to possess: a brain, spinal cord, optic cup and lens, digestive tract, gonads, bones and so on – all initiated by the triploid nucleus of the tumour cell from the kidney cancer.

This being so, we should not be too surprised when, one day, we come across a frog or a mouse or even something bigger perhaps, whose “mothers” have been tumours from a geneticist’s laboratory. What I was not able to get information on, however, is whether such tumour-cell-based individuals are better, equally bad or even worse in fighting cancerous growths, in other words, malignant structures when they occur. And that takes us back to the beginning.

© Dr V.B. Meyer-Rochow and, 2018.
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