Transforming growth factor-beta non-canonical signaling pathway complexes (Non-canonical TGF-β signaling)

The Transforming growth factor-beta (TGF-β) non-canonical signaling pathway complexes encompass a diverse set of Smad-independent cascades activated by the TGF-β receptor complex. These pathways include the mitogen-activated protein kinase (MAPK) branches such as ERK, JNK, and p38, as well as the phosphoinositide 3-kinase (PI3K)/AKT/mTOR axis and Rho-like GTPase signaling [2, 5, 17]. While the canonical Smad pathway primarily regulates gene transcription, these non-canonical complexes often mediate rapid, non-transcriptional effects on the cytoskeleton, cell motility, and survival [7, 17]. In the context of disease, these pathways are frequently hijacked to promote epithelial-mesenchymal transition (EMT), metastasis, and therapeutic resistance in advanced cancers, particularly when the canonical pathway is inactivated by mutations [5, 8, 12]. They also play a critical role in driving the excessive myofibroblast activation and extracellular matrix deposition characteristic of chronic fibrotic disorders [1, 6]. Therapeutic targeting of these complexes involves the use of TGF-β receptor kinase inhibitors, ligand-neutralizing antibodies, and inhibitors of specific downstream kinases [3, 8, 13]. However, the pleiotropic nature of TGF-β signaling presents significant challenges, including potential cardiotoxicity and the risk of promoting skin tumors, necessitating precise patient selection and biomarker-driven approaches [8, 13].

Other names

Non-Smad signaling pathwaysSmad-independent TGF-beta signalingTGF-beta non-canonical signalingNon-canonical TGF-beta pathway

Inhibition of TGF-beta receptor type I (ALK5) kinase activity, neutralization of TGF-beta ligands, and antisense-mediated reduction of TGF-beta expression, which collectively suppress both canonical and non-canonical signaling cascades [3, 8, 13].