Radiotherapy and Solid Tumor Growth
Authors:Nadia Alvarez, Da-Thao Huynh, Huy Nghiem, Vidhi Patel
- John Lowengrub, Chancellor's Professor, Department of Mathematics, University of California Irvine
- Yucheng Hu, Visiting Assistant Professor, University of California Irvine
Experimental results have shown that there are cases in which radiotherapy promotes tumor growth rather than inhibit it. We hypothesize that radiotherapy can reprogram cells into stem-like cells which are more resistant to radiation, and after treatment these cells can proliferate at higher rates. We built a model that displays three species of cells including original stem cells, differentiated stem cells, and induced stem cells, which come from the reprogramming of the differentiated cell population. Along with this model we created ordinary differential equations that show the dynamics of each type of cell population and we studied this model analytically and numerically. We compared our simulation results with experimental data of a breast cancer cell line, provided by the Department of Radiation Oncology at the University of California, Los Angeles. We found that under radiation there is an increase in the rate of dedifferentiation, which is consistent with our hypothesis. Furthermore, by proposing a feedback from the stem cells that negatively regulates the dedifferentiation rate, we are able to accurately fit the experimental data. Thus, we have a working model that explains how radiotherapy may affect the dynamics of in vitro tumor cells. A better understanding of the model may help us improve cancer treatments in the future.