Abstract
The word “niche” is uniquely challenging to define, relying a great deal on context. In adobe homes in the American dessert southwest, exist small hollows in thick adobe walls, called “nichos” which are used to hold objects of devotion or value to the resident, a utility only appreciated by the owner. Similar niches are found in other cultures, including on homes in Malta.
Over the past centuries, science has used classification and definition to expand knowledge and form a foundation for additional studies and advancement. Without a framework on which to both agree and disagree, there is no platform for the discourse of science. To assert knowledge by observation, “I know it when I see it,” as U.S. Supreme Justice Potter Steward stated in reference to obscenity, 1 is an exercise in subjectivism.
No field of cancer research remains as complex as that of the Cancer Stem Cell Niche. While the existence of cancer stem cell niches as a concept is widely accepted, consensus about how to define and identify this phenotype remains elusive. The biology of the niche is subject to debate and even what types of tumors have cancer stem cell niches remains unclear.
The complexity of this “niche” concept is further complicated by the fact that it is visualized in two dimensions. It is accepted that a niche is a three-dimensional entity; however, it cannot simply be assumed to be a bracelet, encircling a vessel, based on the spatial organization surrounding a vessel. This leaves the possibilities that a niche is a nodule that occurs along a vessel, or a more linearly organization forming a coat surrounding a vessel?
Tumor cells demonstrate the perturbation of development to support unstrained proliferation, at the cost of differentiation. Only the lack of nutrients restrains the tumor, and ultimately metastasis is a further manifestation of this behavior to continue to proliferate beyond what can be derived from the local environment. As such, the concept of a cancer stem cell niche is an expansion of the principles of normal growth and development. Again, the fundamentals of nutrients and energy are central—a vessel to supply nutrients, and the most rapid growth in the more fertile environment.
The physical description of a nichos—a niche—larger in the lateral and vertical dimensions than depth that hold objects of value is similar to the paradigm of the cancer stem cell niche—a specialized location of stem cells. However, the lack of definition to the third dimension results in the question is it an acequia, the irrigation ditch, that brings nutrients to the fields and allows life in such harsh environment which is a better paradigm of both growth and development and the cancer stem cell niche.