The Role of Cruciferous Vegetables and Isothiocyanates for Lung Cancer Prevention: Current Status, Challenges, and Future Research Directions

Abstract

Lung cancer remains a leading cause of cancer-related deaths in the United States. Although smoking and air pollution exposure are primary risk factors of lung cancer, diet has also been reported to contribute to lung cancer risk. Cruciferous vegetables contain many bioactive compounds that alter the detoxification process of air-borne carcinogenic compounds and, thereby, may decrease lung cancer risk. In the meta-analysis of 31 observational studies, cruciferous vegetable intake is inversely associated with lung cancer risk (summary odds ratio/relative risk = 0.81 and 95% confidence interval = 0.74-0.89 for comparing the highest with lowest intake categories). More observational studies need to measure urinary isothiocyanate (ITC) concentrations and investigate their association with lung cancer risk in populations with relatively high intake of cruciferous vegetables. Current evidence is limited to two phase 2 clinical trials with incomplete reporting. Hence, more short-term clinical phase 2 trials need to examine effects of various amounts and types of cruciferous vegetables on biomarkers of risk and efficacy before a large phase 3 trial can be conducted to assess effects upon lung cancer risk. This would help further elucidate whether the inverse association observed with self-reported cruciferous vegetable intake is indeed due to ITC content or other bioactive compounds.

Identification and Characterization of Three Epithiospecifier Protein Isoforms in Brassica oleracea

“…So far, the specific role of ESP-catalyzed ETN formation and, hence, their specific role in biotic interactions is still unclear (Jeschke et al, 2016). With regard to human consumption, the aroma and taste of fresh Brassicaceae vegetables likely is influenced by the ESP activity (Zhang et al, 2018). While ITC contribute to the characteristic flavor and pungency of these vegetables (Bell et al, 2018), ETNs have a lower aroma impact.…”

“…Therefore, a higher ESP activity might reduce the taste and flavor of fresh Brassica vegetables. Further, vegetables rich in ESP-activity might have lower health beneficial properties, as protective effects are mainly attributed to ITCs (Zhang et al, 2018). Thus, it is crucial to unravel the role of ESP in planta and to identify strategies for ESP activity reduction in these vegetables.…”

Perspective on dietary isothiocyanates in the prevention, development and treatment of cancer

“…This class of compounds has been investigated for anti-carcinogenic, chemoprotectant, chemopreventive, and anti-cancer activities, in vitro and in animal models, over the past several decades. A number of excellent detailed reviews and perspectives have been published [25][26][27][28][29][30] . Key members of the ITC family found in the diet, SFN, phenethylisothiocyanate (PEITC), and benzyl isothiocyanate (BITC), show antitumor efficacy, perhaps selectively, against a variety of different cancers [31] and thus have received the greatest attention.…”

Evaluation of 2‐Thiothiazolidine‐4‐Carboxylic Acid, a Common Metabolite of Isothiocyanates, as a Potential Biomarker of Cruciferous Vegetable Intake

“…Several dozen types of vegetables make up the cruciferous vegetable family and they have been evaluated as disease preventative and therapeutic agents in both observational studies and in randomized clinical trials . The underlying biological mechanism of these disease‐mitigating effects is governed by the enzymatic conversion of glucosinolates to isothiocyanates by the plant enzyme myrosinase.…”

“…Several dozen types of vegetables make up the cruciferous vegetable family and they have been evaluated as disease preventative and therapeutic agents in both observational studies and in randomized clinical trials. [1][2][3][4] The underlying biological mechanism of these diseasemitigating effects is governed by the enzymatic conversion of glucosinolates to isothiocyanates by the plant enzyme myrosinase. Isothiocyanates, such as sulforaphane (SFN), have potent antibacterial, antifungal, and anticarcinogenic effects [5,6] and have been shown to work through activating the Nrf2-mediated stress response among several other cytoprotective pathways.…”