Inflammatory proteins in obesity may contribute to the risk of colon cancer

A recent study investigated the link between the inflammatory proteins associated with obesity and the risk of colon cancer.

There are approximately 1.3 million new diagnoses of colon cancer annually worldwide. Excess weight is a well-known risk factor for colon cancer in those who fall within a BMI category of overweight and obese.

It is known that obesity creates a state of chronic inflammation in the body, which has been theorized to be the mechanism of how inflammatory proteins can cause colon cancer. This is supported by previous studies that have shown an association between inflammatory proteins and the activation of cellular pathways that can lead to cancer. Past studies in lab rodents have shown that inflammatory proteins are increased in obese rats compared to lean rats, however, this has not been studied in humans.

Researchers in the United States explored the level of inflammatory proteins in obese human subjects and whether it is associated with colon cancer risk in a study and published their results in Cancer Epidemiology Biomarkers & Prevention. The study included subjects who were in the normal BMI range and in the overweight or obese BMI range. A total of 42 Caucasian participants were included in the study analysis with 26 being obese and 16 having normal BMI. The researchers took blood samples and biopsies from the colon to analyze the level of inflammatory proteins, known as cytokines.

The results showed a significant increase in inflammatory proteins in obese patients when compared to lean patients. This was a linear relationship, where the level of inflammatory proteins increased with an increase in BMI. Many of the study subjects were regular users of NSAIDs, and researchers found that they had a lower level of inflammatory proteins in both the obese and lean groups compared to subjects who did not take NSAIDs regularly.

The researchers also examined obesity-related changes in gene expression and cell signaling pathways. They found that certain genes that promote inflammatory proteins and cancer cell signaling pathways were increased in the colons of obese patients.

The study’s small population, as well as their use of all Caucasian subjects to rule out any gene differences due to ethnicity, limit the generalizability of their results. While the study demonstrates that an increase in BMI is associated with an increase in inflammatory proteins, it cannot confirm that the changes in gene expression in the colon are because of the inflammatory proteins. Regardless, the researchers conclude that inflammatory proteins in the colon may explain the association seen between obesity and colon cancer.

Written by Maggie Leung, PharmD

References:

  1. Pfalzer, A. C., Leung, K., Crott, J. W., Kim, S. J., Tai, A. K., Parnell, L. D., . . . Mason, J. B. (2018). Incremental Elevations in TNFα and IL6 in the Human Colon and Procancerous Changes in the Mucosal Transcriptome Accompany Adiposity. Cancer Epidemiology Biomarkers & Prevention. doi:10.1158/1055-9965.epi-18-0121
  2. Gallagher, S. (2018, October 10). New study finds that inflammatory proteins in the colon increase incrementally with weight. Retrieved from https://www.eurekalert.org/pub_releases/2018-10/tuhs-nsf101018.php