Signalling pathways regulated by FSTL1 in inflammation and potential therapeutic applications (Review)

Follistatin‑like protein 1 (FSTL1), a secreted glycoprotein, serves a key role in regulating various biological processes. The present review explores the molecular mechanisms through which FSTL1 influences inflammation, cellular senescence and tumour progression. As a multifunctional protein with both autocrine and paracrine properties, FSTL1 regulates cell survival, proliferation, differentiation and migration, while also modulating immune responses. Evidence indicates that FSTL1 exerts context‑dependent regulatory effects on pathological conditions by modulating signalling pathways, such as TGF‑β, NF‑κB and MAPK. Furthermore, increased FSTL1 expression has been found in the inflammatory synovial tissues of patients with osteoarthritis and it contributes to nucleus pulposus cell inflammation. In conclusion, the distinctive structural features and widespread expression of FSTL1 position it as a key target for understanding the mechanisms underlying inflammation, senescence and tumourigenesis, providing potential options for novel diagnostic and therapeutic strategies for these conditions.