How does competition between cells affect cancer growth?

Zhang, X., Li, S., Malik, I. et al. Reprogramming tumour-associated macrophages to outcompete cancer cells. Nature (2023). https://doi.org/10.1038/s41586-023-06256-5

Cell fitness is a method by which cells in the body are selected based on their fitness, or ability to survive. Although a cell may be viable, it is not necessarily the strongest or best cell in terms of maintaining the health of the organism. As a result, a variety of methods exists by which cells that are less fit die and cells that are fitter survive and proliferate (grow in number). For example, when less fit cells exist, the cells nearby are able to participate in cell sensing. Cells release various molecules called signaling molecules which are received by other cells’ receptors. These signals relay messages to each cell, such as whether the nearby cell is fit or not. When a less fit cell is sensed, it undergoes the cell death process while the more fit cells around it begin to proliferate to replace the cell with a fit cell.

This process of determining cell fitness and maximizing it is called cell competition. While this process can be seen as beneficial to support the health of the organism by creating more fit cells, it can also be a negative. In some cases, aggressive cancer cells outcompete healthy cells in the body, which leads to greater cancer growth. Previous research has not addressed how different biological factors or entities can affect the activity of tumorous cells. This experiment, however, discussed macrophages, which are a type of white blood cell that kills microorganisms, and how they can be upgraded to outcompete cancer cells.

In a test trial done on mice, cancer cells were originally outcompeting macrophages that were supposed to help eliminate cancer growth. Researchers limited the amount of protein being fed to these mice, which prevented cell signaling in the cancer cells. The proteins had originally incited the cancer cell’s response of proliferating because they were received by signaling molecules, ultimately relaying the message to grow to the cell. However, without these proteins being supplied through the mice’s diets, the cancer cells no longer grew as rapidly. As a result, the cancer cells became less fit and thus were able to be outcompeted by cancer-killing cells like macrophages.

When the protein-lacking diet was given to the mice, molecules called transcription factors in the cancer cells did not activate, preventing the cancer cells from undergoing cell division. Transcription factors bind to the cell’s DNA and spur the cell to replicate its genetic material. With this new genetic material, the cell splits and creates an identical cell, which is how cells proliferate. However, without transcription factors, the cancer cell was not able to replicate its genetic material and thus did not create more cancer cells.

As researchers continue to learn more about how environmental factors such as diet can influence the growth of cancerous tumors, new types of cancer therapies will be developed. This study is limited right now as it has only been tested on mice, not on human subjects yet. However, the results showing how limiting proteins in diet can reduce tumor growth by helping healthy cells outcompete cancerous cells offer a promising treatment for cancer in the future.

By Jeannine

References:

Brody, Lawrence. “DNA Replication.” Genome.Gov, 1 July 2023, www.genome.gov/genetics-glossary/DNA-Replication#:~:text=DNA%20replication%20is%20the%20process,with%20its%20own%20complete%20genome.

“Gene Expression and Regulation | AP®︎/College Biology.” Khan Academy, 2017, www.khanacademy.org/science/ap-biology/gene-expression-and-regulation.

Gregorio, Aida D, et al. Cell Competition and Its Role in the Regulation of Cell Fitness from Development to Cancer, 2016, www.cell.com/developmental-cell/pdf/S1534-5807(16)30587-1.pdf.