Nitrite can inhibit cancer cell progression at low doses during the early stages of colon cancer cell development, according to a new study by the University of Texas and Michigan State University.
Colorectal cancer is one of the leading causes of cancer in the United States and some studies have suggested that the consumption of nitrite-containing processed increases colon cancer risk. Yet, vegetable consumption has been associated with decreasing cancer risk, despite containing levels of endogenous nitrite.
This conflicting paradigm of whether nitrite promotes or blocks phenotypes associated with the promotion of cancer in colon cells was examined. Cell proliferation was measured after difference stages of SW1116, HCT15, SW480 and COLO205 human colon cancer cell lines were treated with different concentrations of nitrite for 24 or 48 hours.
Nitrite concentrations of 10 nM to 100 μM inhibited stage 2 cell proliferation for SW480, and inhibited stage 3 SW480 growth in a dose-dependant manner. Also inhibited were stage 3 HCT15 cell growth when subjected to 100 nM and 1 μM nitrite concentrations. Cell growth was seen in stage 4 SW480 cells at 100 μM nitrite concentration levels. No effect was observed for stage 1 SW1116 colon cancer cells at any nitrite treatment level.
Researchers concluded that these data indicate that nitrite can inhibit cancer cell progression at low doses and early stage, but may promote cancer cell progression at higher doses in stage 4 colon cancer.
This work may begin to explain the conflicting reports on dietary nitrite exposure and risk of certain cancers, but additional research to further understand the relationship of dietary nitrite and colon cancer is needed. This research was presented at the American Institute for Cancer Research on 21-22 October 2010.
Source: American Meat Institute - AMI