Single-molecule force spectroscopy study of the effect of cigarette carcinogens on thrombomodulin-thrombin interaction

Exposure to cigarette smoke is a major risk factor for cancer and cardiovascular disease. Thrombosis is regarded as the main reason for smoking-related cardiovascular disease. However, the detail mechanism of how smoking promotes thrombosis is not fully understood. In this work, we investigated the impacts of one major cigarette carcinogens 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) as well as its metabolite 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) on a key process in thrombosis regulation: thrombin-thrombomodulin (TM) binding. Atomic force microscopy based single-molecule force spectroscopy was applied to measure both in vitro and in vivo binding force of thrombin to TM in the absence and presence of NNK and NNAL respectively. The results revealed that NNK and NNAL can reduce the binding probability of TM and thrombin. The inhibition effect and underlying mechanism was further studied by molecular simulation. As indicated by our results, the cigarette carcinogens could cause a higher risk of thrombosis through the disruption of TM-thrombin interaction.