Role of SCAL1 in Modulating Oxidative Stress, Cancer Stemness, Apoptotic Resistance in Tumorigenic Differentiation of Cigarette Smoke-Exposed BEAS-2B Cells

Abstract

The smoke and cancer-associated lncRNA 1 (SCAL1) is an emergent biomarker in lung cancer. However, the precise role of SCAL1 as a mediator of tobacco smoke-induced lung carcinogenesis remains unclear. BEAS-2B cells were cultured and exposed to 20% cigarette smoke extract (CSE), followed by quantification of SCAL1. We evaluated the impact of SCAL1 on cell viability, ROS mitigation, cancer stemness, tumorigenic differentiation, cellular invasiveness, and apoptosis for different CSE incubation time points through SCAL1 expressional modulation using SCAL1-specific siRNAs and scrambled controls. We observed an upregulation of SCAL1 in cells exposed to CSE for 2, 4, and 6 hours, with the highest expression observed at 6 hours (p<0.001). Exposure of BEAS-2B cells to CSE showed the formation of focal adhesions and stress fibers resembling tunneling nanotubes. Intracellular ROS levels significantly increased upon CSE exposure compared to control cells (p<0.05). We found increased levels of anti-apoptotic and cancer stem (CSC) cell markers like BCL2, ALDH1A1, CD133, CD44, and TCTP and decreased levels of TP53 in CSE-exposed cells. Knockdown of SCAL1 using siRNA transfection reversed these effects at all time points. Additionally, we observed a significant decrease in the number of spheroid colonies in siSCAL1 (+) cells compared to siSCAL1 (-) cells (p<0.01) exposed to CSE. SCAL1 is pivotal in mediating cellular responses to cigarette smoke, leading to tumorigenic differentiation of BEAS-2B cells. Understanding the mechanisms could provide valuable insights into lung cancer pathogenesis and therapeutic approaches.