Role of microbiome in lung cancer progression

Abstract

Lung cancer kills more people globally than any other cancer. Pre-invasive lesions can be observed in the airways before developing to lung squamous cell carcinoma (LUSC). The lung is an organ constantly exposed to the environment. It is now clear that the lung has a distinct microbiome and that this may influence the development of lung cancer. However, the role of the pre-invasive lesions’ microbiome in influencing the pre-invasive LUSC carcinoma-in-situ (CIS) lesions progression remains unknown. The aim of this project is to define the microbiome composition and diversity in progressive and regressive pre-invasive lung cancer lesions. Bioinformatics analysis was performed on 39 pre-invasive CIS lesions (progressive n = 29, regressive n =10). Immunohistochemistry using an antibacterial lipopolysaccharide (LPS) antibody was performed on 13 Formalin-Fixed Paraffin-Embedded (FFPE) pre-invasive CIS lesions. (progressive n = 6, regressive n = 7). Quantitative PCR was used to detect to detect the expression of the bacterial 16S rRNA gene in pre-invasive CIS lesions. I observed that the number of genus and species of bacteria was significantly higher in regressive CIS lesions than those that progress to cancer (p-value <0.0001). The Haemophilus influenzae and Staphylococcus epidermidis were the most abundant bacterial species in progressive and regressive CIS lesions, respectively. The bacterial 16S rRNA gene was not detected in progressive and regressive CIS lesions. The presence of gram-negative bacteria was detected only in three pre-invasive CIS lesions. In conclusion, I didn’t observe any significant difference in bacterial diversity between progressive and regressive CIS lesions that might be due to the small number of CIS samples analyzed.