Integrative Transcriptomic Analysis Decodes the Interplay Between Aging, Senescence, and Cancer

Cancer risk increases with age, and cellular senescence may be a major contributor to cellular carcinogenesis. Enormous efforts have been made to investigate the interrelation between aging and tumors, but little is known about the comparative features of normal aging, cellular senescence, and cancer at single-cell resolution. By integrating analyses of genomics, epigenomics, and bulk and single-cell transcriptomics, we revealed a directionally opposite transcriptional profile between cellular senescence and tumorigenesis at the single-cell level, which may be affected by epigenomic regulations. A total of 648 aging-dependent senescence-associated coregulated modules (SACMs), disproportionately affecting the reproductive systems of both females and males, were initially defined across 17 tissues. Single-cell analysis revealed that aging primarily affects endothelial cells, followed by T cells, epithelial cells, macrophages, and fibroblasts. Opposite directions of change in gene expression between aging and cancer can commonly be observed in endothelial, fibroblast, and epithelial cells, which may prompt the opposing patterns of gene expression between tissue aging and epithelial carcinoma at the bulk level. A similar pattern of expression can be observed in immune cells, which are characterized by decreased self-renewal with aging, but this pattern is reversed in epithelial carcinoma. Our study highlighted the role of senescence as a natural barrier against tumor formation and supported the idea that aging-related systemic environment changes create a protumorigenic milieu.