Bhas 42 cell transformation activity of cigarette smoke condensate is modulated by selenium and arsenic

Abstract

Cigarette smoking remains a major health risk worldwide. Development of newer tobacco products requires the use of quantitative toxicological assays. Recently, v-Ha-ras transfected BALB/c3T3 (Bhas 42) cell transformation assay was established that simulates the two-stage animal tumorigenesis model and measures tumor initiating and promoting activities of chemicals. The present study was performed to assess the feasibility of using this Bhas 42 cell transformation assay to determine the initiation and promotion activities of cigarette smoke condensate (CSC) and its water soluble fraction. Further, the modulating effects of selenium and arsenic on cigarette smoke-induced cell transformation were investigated. Dimethyl sulfoxide (DMSO) and water extracts of CSC (CSC-D and CSC-W, respectively) were tested at concentrations of 2.5-40 µg mL(-1) in the initiation or promotion assay formats. Initiation protocol of the Bhas 42 assay showed a 3.5-fold increase in transformed foci at 40 µg mL(-1) of CSC-D but not CSC-W. The promotion phase of the assay yielded a robust dose response with CSC-D (2.5-40 µg mL(-1)) and CSC-W (20-40 µg mL(-1)). Preincubation of cells with selenium (100 nM) significantly reduced CSC-induced increase in cell transformation in initiation assay. Co-treatment of cells with a sub-toxic dose of arsenic significantly enhanced cell transformation activity of CSC-D in promotion assay. The results suggest a presence of both water soluble and insoluble tumor promoters in CSC, a role of oxidative stress in CSC-induced cell transformation, and usefulness of Bhas 42 cell transformation assay in comparing tobacco product toxicities and in studying the mechanisms of tobacco carcinogenesis.

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

“…Conversely, we have shown that the particulate matter (ACM) from e‐cigarettes is negative in the Bhas 42 CTA when tested at concentrations up to 120 µg/mL (77 ng/mL nicotine). This study follows our own previous findings that the Bhas 42 CTA can distinguish between the potential promotion activity of a conventional cigarette and a tobacco heating product [Breheny et al, ], and supports the work of others who demonstrated the potential use of the assay in tobacco product assessment [Weisensee et al, ; Han et al, ].…”

“…In recent years, this assay has undergone a number of international validation studies and is now the subject of an OCED guidance document [Organisation for Economic and Cooperative Development, ]. Weisensee et al [] and Han et al [] have shown that Bhas 42 CTA could be useful in assessing the promoter activity of complex mixtures such as cigarette smoke. Their work showed that total particulate matter (TPM) from a reference cigarette induced cell transformation in a concentration‐dependent manner.…”

Exposure of Human Lung Cells to Tobacco Smoke Condensate Inhibits the Nucleotide Excision Repair Pathway

“…It introduces DNA damage [ 40 – 43 ]. It also induces human and mammalian cell transformation [ 44 – 46 ] and tumor formation when applied to mouse skin [ 47 – 49 ]. While it is well established that cigarette smoke introduces a variety of different types of DNA damage, it is less clear how smoke exposure influences DNA repair efficiency and DNA damage response pathways.…”

Hazard assessment of air pollutants: The transforming ability of complex pollutant mixtures in the Bhas 42 cell model_suppl

“…Although the Bhas 42 CTA was validated using single chemicals (Sakai et al, 2011), the test method is technically applicable to mixtures and has been used to investigate the transforming effects of cigarette smoke condensate (Weisensee et al, 2013;Han et al, 2016) and PM extracts (Ohmori et al, 2013). Indeed, the original source of Bhas 42 cells, BALB/c A31-1-1, can sustain the metabolism of PAH to carcinogenic intermediates (Kakunaga and Crow, 1980;Lo and Kakunaga, 1982).…”