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M.H. Lee
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P1.04 - Poster Session/ Biology, Pathology, and Molecular Testing (ID 233)
- Event: WCLC 2015
- Type: Poster
- Track: Biology, Pathology, and Molecular Testing
- Presentations: 1
- Moderators:
- Coordinates: 9/07/2015, 09:30 - 17:00, Exhibit Hall (Hall B+C)
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P1.04-078 - Induction of Achaete-Scute Homologue 1 (ASCL1) by Cigarette Smoke Condensate in A549 Cells (ID 326)
09:30 - 17:00 | Author(s): M.H. Lee
- Abstract
Background:
About 10% of lung adenocarcinomas express neuroendocrine features, which are thought to denote a subset of adenocarcinomas with poor prognosis. Achaete-scute homologue 1 (ASCL1) is a transcription factor implicated in the neuroendocrine differentiation of lung tissue. Recently, ASCL1 was identified as a neuroendocrine marker in lung adenocarcinomas, and its expression was upregulated in lung adenocarcinomas of smokers when compared to adenocarcinomas of non-smokers and other types of lung cancers. ASCL1 expression in the peripheral airways of cancer-free smokers has not been studied. Moreover, the effect of cigarette smoke exposure on the neuroendocrine differentiation of lung cancer cells has not been examined in vitro.
Methods:
Distal airway brushings for epithelial cells were obtained in 8 subjects who participated in CT scan lung cancer screening at the NYU Lung Cancer Biomarker Center (part of the NCI Early Detection Research Network); never (n=1), former (n=4) and current (n=3) smokers. ASCL1 mRNA expression was measured using real time reverse transcription polymerase chain reaction (RT-PCR). A549 cell line was incubated with cigarette smoke condensate (CSC; extracted to DMSO) at 10 or 40 mcg/mL for 4, 24 or 48 hours. Following the incubation periods, ASCL1 expression levels were measured via western blot with lamin B1 as the nuclear protein loading control. Three individual experiments were performed. Statistical analyses were performed with Kruskal-Wallis test (RT-PCR) and Student's t-test (western blot). Figure 1
Results:
Real time RT-PCR data for ASCL1 in the distal airway brushing samples of the 8 subjects suggested a trend toward higher ASCL1 mRNA titers (p = 0.26) in current smokers (mean = 33 pack-years) compared to former smokers (mean = 51 pack-years), whose ASCL1 mRNA expression levels were higher than that of a never-smoker [Figure 1A]. A549 cells exposed to 10 mcg/mL of CSC for 4 hours had 4.1 fold (p = 0.023) and 2.0 fold (p = 0.017) increases in ASCL1 expression compared to those exposed to 1% DMSO and serum-free media (SF) only, respectively [Figure 1B]. No statistically significant change in ASCL1 expression was noted in the other CSC exposure groups.
Conclusion:
CSC induced ASCL1 expression in A549 cells, and the stimulatory effect of CSC was no longer observed at the higher concentration and the longer exposure times. This in vitro finding is in agreement with the RT-PCR data, which also suggest a trend toward increased ASCL1 expression with more recent smoking history in the distal airways of cancer-free human subjects.
