Effects of Aerosol Extract From Heated Tobacco Products on Senescence-Associated Gene Expression in Human Lung Fibroblasts

AIM: Cellular senescence is associated with an increased risk of various diseases. Although heated tobacco products (HTPs) have become widespread substitutes for conventional combustible cigarettes, their role in cellular senescence remains unclear. Therefore, we evaluated the effects of HTP aerosol extract on cytotoxicity and expression of senescence-associated genes in human lung-derived normal diploid fibroblasts (TIG-1). METHODS: TIG-1 cells were exposed to smoke extract from a 1R6F reference cigarette (RC) or aerosol extract from a Ploom X HTP. Cell membrane damage and cellular metabolic activity were analyzed by lactate dehydrogenase and WST-8 assays, respectively. The mRNA levels of senescence-associated genes and genes encoding xenobiotic-metabolizing enzymes were analyzed using RT-qPCR following single or repeated exposure. Replicative senescence and doxorubicin (DOX)-induced senescence were also evaluated. RESULTS: HTP was less cytotoxic than RC. Repeated exposure to RC and HTP (HTP at a 10-fold higher concentration) increased the expression levels of CDKN2A, IL1B, MMP1, AHR, CYP1A1, and CYP1B1, and decreased that of MMP13, showing changes similar to replicative senescence or DOX-induced senescence. MMP2 and MMP7 expression levels increased only by RC, whereas MMP12 expression was selectively induced by HTP. CONCLUSION: Although less cytotoxic than RCs, repeated exposure to HTP aerosols may influence senescence-associated factors.