Carcinogenic nitrosamines in traditional beer as the cause of oesophageal squamous cell carcinoma in black South Africans

• Published in: South African medical journal Vol. 105; no. 8; pp. 656 - 658
• Main Authors: Pillay, Viness, Isaacson, Charles, Mothobi, Pride, Hale, Martin, Tomar, Lomas Kumar, Tyagi, Charu, Altini, Mario, Choonara, Yahya Essop, Kumar, Pradeep
• Format: Journal Article
• Language: English
• Published: South Africa Health & Medical Publishing Group 01-08-2015
• Subjects: African Continental Ancestry Group; Beer; Beer - analysis; Carcinogens; Carcinoma, Squamous Cell - chemically induced; Carcinoma, Squamous Cell - ethnology; Care and treatment; Chemotactic Factors - metabolism; Chromatography, High Pressure Liquid; Esophageal Neoplasms - chemically induced; Esophageal Neoplasms - ethnology; Health aspects; High performance liquid chromatography; Humans; Molecular Docking Simulation; N-Nitrosopyrrolidine - pharmacology; Nitrosamines - adverse effects; Nitrosamines - analysis; Nitrosamines - pharmacology; Nitrosoamines; Risk factors; S100 Proteins - metabolism; South Africa; Squamous cell carcinoma; South Africa
• DOI: 10.7196/SAMJnew.7935
• ISSN: 0256-9574

Before the 1930s, squamous cell carcinoma (SCC) of the oesophagus was almost unknown among black South Africans. From the 1930s the annual frequency rose. A dietary cause was sought, the staple diet of black people having changed from sorghum to maize (corn), with traditional beer being brewed from maize. Carcinogenic N-nitrosamines in traditional beer were suggested as a cause of SCC of the oesophagus, with Fusarium moniliforme, a corn saprophyte, thought to play a role.
To confirm the presence of N-nitrosamines in traditional beer and demonstrate a mechanism for the oncogenesis of oesophageal carcinoma.
Analysis by high-performance liquid chromatography was conducted for the identification of nitrosamines in traditional beer samples, and molecular docking studies were employed to predict the affinity between N-nitrosamines and the S100A2 protein.
Carcinogenic N-nitrosamines were identified in all six samples of traditional beer examined (N=18 analyses), and docking studies confirmed a high affinity of the nitrosamine N-nitrosopyrrolidone with the S100A2 protein. This may result in the altered expression of the S100A2 protein, leading to tumour progression and prognosis.
It is suggested that carcinogenic N-nitrosamines in traditional beer are a major factor in the causation of SCC of the oesophagus in black South Africans. N-nitrosamines have been shown to produce cancer experimentally, but there has not been conclusive epidemiological evidence that N-nitrosamines are carcinogenic to humans. This study is the first to demonstrate the potential link between N-nitrosamines and a human tumour.