Comparative tumor promotion assessment of e‐cigarette and cigarettes using the in vitro Bhas 42 cell transformation assay

Abstract

In vitro cell transformation assays (CTA) are used to assess the carcinogenic potential of chemicals and complex mixtures and can detect nongenotoxic as well as genotoxic carcinogens. The Bhas 42 CTA has been developed with both initiation and promotion protocols to distinguish between these two carcinogen classes. Cigarette smoke is known to be carcinogenic and is positive in in vitro genotoxicity assays. Cigarette smoke also contains nongenotoxic carcinogens and is a tumour promoter and cocarcinogen in vivo. We have combined a suite of in vitro assays to compare the relative biological effects of new categories of tobacco and nicotine products with traditional cigarettes. The Bhas promotion assay has been included in this test battery to provide an in vitro surrogate for detecting tumor promoters. The activity of an electronic cigarette (e‐cigarette; Vype ePen) was compared to that of a reference cigarette (3R4F) in the promotion assay, using total particulate matter (TPM)/aerosol collected matter (ACM) and aqueous extracts (AqE) of product aerosol emissions. 3R4F TPM was positive in this assay at concentrations ≥6 µg/mL, while e‐cigarette ACM did not have any promoter activity. AqE was found to be a lesssuitable test matrix in this assay due to high cytotoxicity. This is the first study to use the Bhas assay to compare tobacco and nicotine products and demonstrates the potential for its future application as part of a product assessment framework. These data add to growing evidence suggesting that e‐cigarettes may provide a safer alternative to traditional cigarettes. Environ. Mol. Mutagen. 58:190–198, 2017. © 2017 The Authors. Environmental and Molecular Mutagenesis Published by Wiley Periodicals, Inc.

The in vitro assessment of a novel vaping technology

“…Plates were manually scored, and results evaluated as previously described [ 12 , 29 , 37 , 38 , 42 ].…”

E‐cigarettes: voltage‐ and concentration‐dependent loss in human lung adenocarcinoma viability

“…There is no doubt that tobacco smoke has a devastating effect on the respiratory and cardiovascular systems, and it is believed to be the root cause of the development of various cancers. The majority of currently available studies related to e‐cigarette aerosol toxicity are focused on the assessment of its toxicity on respiratory cells (Anthérieu et al, ; Azzopardi et al, ; Behar, Wang, & Talbot, ; Cervellati et al, ; Leslie et al, ; Misra, Leverette, Cooper, Bennett, & Brown, ; Neilson et al, ; Scheffler, Dieken, Krischenowski, & Aufderheide, ), cardiovascular cells (Anderson, Majeste, Hanus, & Wang, ; Antoniewicz et al, ; Farsalinos et al, ; Putzhammer et al, ) and genotoxicity (Anderson et al, ; Breheny, Oke, Pant, & Gaça, ; Ganapathy et al, ; Misra et al, ; Yu et al, ). Various cell lines and commercially available (CA) atomizers/liquids used to generate aerosol were used for these studies.…”

Collecting e‐cigarette aerosols for in vitro applications: A survey of the biomedical literature and opportunities to increase the value of submerged cell culture‐based assessments

“…Upon inspection, 47 publications from the 1543 were found to contain relevant empirical data, while the remaining were rejected because of lack of direct relevance to e‐cigarette aerosol collection for in vitro application and/or absence of empirical information. Interestingly, two of these publications reported two distinct collection methods each (Breheny et al, 2017; Rayner et al, 2019). Thus, in total, there were 49 individual collection methods itemized in the database.…”

“…Among the 47 relevant publications identified in the survey (including studies Breheny et al, 2017 and Rayner, Makena, Prasad, & Cormet‐Boyaka, 2019 that described two methods each), 57% (28/49) of the collection methods were defined as “bubble‐through.” This is a method whereby aerosol generated from an e‐cigarette is bubbled into a solvent, resulting in a solution containing the aerosol constituents, which can be subsequently applied to cell cultures. Furthermore, all 28 examples found in this survey employed water‐based protic solvents—cell culture medium, FBS, PBS, or HEPES‐buffered saline—and, thus, generated AQEs.…”