Exposure to water-pipe smoking dysregulates a set of genes associated with breast cancer development and an unfavorable outcome

Background: Water-pipe smoking (WPS), a predominant method of tobacco consumption, is common amongst young females in the Middle East. WPS smoke consists of toxins analogous to the ones that exist in cigarette smoke and frequently correlates with the onset of several types of human cancers including breast. However, the potential target genes and their underlying mechanisms in the initiation and/ or progression of human cancers, especially breast, due to WPS exposure are still unknown. Materials and Methods: In this investigation, we explored the effect of WPS chronic exposure on human normal mammary epithelial cells and analyzed alterations in the differentially ex-pressed gene (DEG) targets using the NanoString nCounter PanCancer Pathways Panel consisting of 770 gene transcripts and a quantitative real-time polymerase chain reaction (PCR) analysis. Results: Our NanoString analysis identified 13 genes dysregulated under the effect of WPS exposure involved in regulating signal transduction, cell cycle, cell motility, proliferation and migration/invasion as well as the inflammatory response. We further performed an in silico analysis to investigate the effect of the identified genes in the prognosis of breast cancer patients and reported those DEGs that directly correlated with smoking and were upregulated in breast cancer in comparison with normal tissue. Moreover, the Kaplan–Meier curve analysis showed a significant correlation be-tween WPS-dysregulated genes (MX1, CCL8, GNGT1 and MMP9) and relapse-free survival in breast cancer patients. Conclusions: Our data clearly suggest that exposure to WPS can alter the expression of key regulator genes involved in the pathogenesis of breast cancer, thereby affecting the breast cancer prognosis.