Integrated Evolutionary and Multi-Omic Analysis of STAT Family Activation Across Solid Tumors

Background/Objectives: The STAT (Signal Transducer and Activator of Transcription) family of seven transcription factors mediates cytokine and growth-factor signaling, regulating proliferation, differentiation, and immunity. While STAT3/STAT5 are established oncogenes and STAT1/STAT2 are classically viewed as tumor suppressors, emerging evidence indicates context-dependent roles in tumorigenesis. This study aimed to integrate evolutionary analysis with bulk transcriptomic, regulon, single-cell, and exploratory chromatin-binding analyses of the STAT family in human solid tumors. Methods: Orthologs and paralogs of human STAT genes (81 sequences total) were retrieved across vertebrates and invertebrates; a phylogenetic tree was constructed using MUSCLE alignment and Neighbor-Joining in MEGA12. Differential expression was assessed in TCGA solid tumors versus GTEx normal tissues. Master-regulator activity was inferred using the corto algorithm. Single-cell RNA-seq datasets were used to compare malignant and non-malignant cell populations. STAT1 chromatin binding was examined via ChIP-seq in interferon-stimulated HeLa and K562 cells. Results: Phylogeny resolved seven conserved vertebrate clades, with endocrine-responsive STAT3/STAT5 showing higher conservation and immune-associated STAT1/STAT2/STAT4/STAT6 exhibiting faster divergence. The majority of STAT genes were frequently upregulated across multiple solid tumors, with activated regulons confirming functional transcriptional engagement. Single-cell analysis demonstrated tumor-cell-autonomous upregulation of STAT1 and STAT2 in the HNSCC dataset. STAT1 ChIP-seq revealed asymmetric forward/reverse-strand read density around peak summits, supporting non-canonical DNA recognition. Conclusions: The STAT family operates as an evolutionarily conserved, broadly activated transcriptional module in human solid cancers, combining quantitative upregulation with qualitative shifts in DNA-binding dynamics. These findings refine our understanding of JAK/STAT signaling in oncology and highlight opportunities for network-targeted therapies.