Abstract
It is proposed here that malignancies of the central nervous system (CNS) are capable of recruiting non-malignant CNS precursor cells and that doing so worsens the course of the disease. In particular, the argument is put forward that such tumors can activate resident neural stem cells, attract them or their progeny to the tumor site, and induce them to proliferate. What begins as a normal wound repair response by the recruited cells can eventually result in augmentation of the tumor. In support of this hypothesis, evidence consistent with the ideas proposed is presented. Since these recruited cells are non-malignant, it should be possible to interfere with this process. This would not necessarily remove the threat posed by the cancer, but could beneficially impact patients by slowing progression. Interfering with recruitment could simultaneously serve to block autocrine stimulation by tumor cells. In contrast, introducing exogenous stem cells could exacerbate the recruitment process unless measures are taken to preclude this possibility. Finally, it is worth noting that the situation described in the current hypothesis might apply to a variety of other stem and precursor cell-containing systems throughout the body.
Keywords: Cancer, stem cells, brain tumors, astrocytoma, retinoblastoma, growth factors, neural precursor cells, wound repair, cellular migration, tropism
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