Explaining Aberrations of Cell Structure and Cell Signaling in Cancer Using Complex Adaptive Systems

Cancer is identified by aberrations in cellular structure and cellular function. Gross morphological changes are evident in both the cellular and nuclear membranes in tumor cells. The progression of many cancers has been traced to a succession of genetic mutations that ultimately result in altered protein function. Structure and function, however, are not mutually exclusive. Conformational changes in a protein will alter its function, while aberrant expression of a protein can lead to altered cell morphology. The link between structure and function is the array of signal transduction pathways that detect stimuli from inside and outside of the cell, and transmit information, through a series of proteins, to other parts of the cell. One way to gain a better understanding of how structure and function are interrelated is to devise models that describe these pathways. In addition, a model must be able to predict how perturbations to a system will be physically manifested. Until recently, most modeling paradigms have relied on a top---down approach: collect as much data as possible about the system of interest, and derive equations that mimic the system. Unfortunately, these types of models are often based on incomplete data. Many assumptions, therefore, must be made; this leads to an inaccurate description of the system. The development of the science of complex adaptive systems has introduced a new modeling paradigm. Modeling using the tools of complex adaptive systems takes a bottom-up approach: systems are distilled to their basic components and rules are constructed that describe their behavior. This behavior can be changed (i.e., adapted) by using functions analogous to chromosomal manipulations (e.g., crossing over). In this review, several signal transduction pathways and cellular structures will be examined using this bottom-up approach.