Researchers have found a link between a type of reflux and the development of cancerous cells in the hypopharynx (that’s the area behind the tongue and above the oesophagus).
The study examines how the enzyme pepsin can contribute to laryngeal inflammation during a reflux episode as well as its role in the promotion of epithelial cell proliferation and carcinogenesis in the larynx and pharynx.
Pepsin is an enzyme that helps digest proteins in the stomach. Normally, it works in a very acidic environment in the stomach with a pH around 2.0.
In this study, when pepsin is exposed to a slightly acidic pH of 6.0 or a neutral pH of 7.0, it can cause changes in certain cells in the throat (hypopharyngeal primary cells) that are associated with the activation of a protein called Epidermal Growth Factor Receptor (EGFR).
EGFR is a protein that helps cells grow and divide, which is important for normal cell growth and repair. However, when EGFR is overactive or ‘activated’ too much, it can contribute to the development of cancer.
Exposure to pepsin
The study – published in the International Journal of Molecular Sciences – suggests that exposure to pepsin at slightly acidic or neutral pH may promote this oncogenic effect by activating EGFR in these cells in the throat. This is important because it suggests a possible link between laryngopharyngeal reflux (LPR), which can cause pepsin to enter the throat, and the development of cancer in the throat.
If pepsin is refluxed or regurgitated up into the throat and mouth, it can be exposed to a less acidic or neutral pH environment, such as a pH of 6.0 or 7.0. This can happen, for example, in cases of gastroesophageal reflux disease (GERD) or LPR, where stomach contents and acid can flow back up into the oesophagus and throat.
The activation of the Epidermal Growth Factor Receptor protein can promote the growth and spread of cancer cells in the hypopharynx when exposed to pepsin in a less acidic environment.
When EGFR is activated, it can trigger other cancer-promoting pathways such as AKT/mTOR, STAT3 and NFκB, which can further promote the growth and survival of cancer cells in the hypopharynx.
Thus, EGFR plays a key role in the development and progression of pepsin-induced cancer in the hypopharynx under less acidic conditions.
Researchers behind the study say they still need to do more tests to understand exactly how the pH level affects cell growth and the oncogenic effect of pepsin in real-life situations.
Peptest measures the concentration of pepsin in saliva to show the severity of reﬂux. The detection limit of 16ng/mL is the lowest amount of pepsin that can be measured.