Hydroponic Growth of [¹³C]-Labeled Tobacco for DNA Damage Studies in Cigarette Smokers

Cigarette smoking is the acknowledged major cause of cancers of the lung and oral cavity and is an established important risk factor for multiple other cancers. DNA addition products (DNA adducts) caused by cigarette smoking are critical factors in its mechanism of carcinogenesis. However, most DNA adducts detected to date in humans cannot be specifically ascribed to smoking but rather have multiple exogenous and endogenous sources. In the study reported here, we prepared [¹³C]-labeled tobacco to address this problem. We report for the first time the successful growth from seeds to flowering under hydroponic conditions of highly [¹³C]-labeled tobacco in a controlled ¹³CO₂ environment. The standard growth procedure with optimized conditions is described in detail. The [¹³C]-enrichment rate was assessed by quantifying nicotine and sugars and their [¹³C]-isotopologues in this tobacco using high-resolution mass spectrometry, reaching >94% in the tobacco leaves. The [¹³C]-labeled leaves after curing will be used to make cigarettes, allowing investigation of the specific contributions of tobacco smoke carcinogens to identified DNA adducts in smokers.