Abstract:
Background:
The insulin-like growth factor-1 receptor β (IGF-1Rβ) is a receptor tyrosine kinase that facilitates oncogenic signalling, enhancing cancer cell proliferation, survival, and metastasis via both membrane and nuclear pathways. Proteomic investigation of hepatocellular carcinoma (HepG2) cells via LC–MS/MS identified S100A11 as a possible interacting protein of IGF-1Rβ. S100A11, a calcium-binding protein within the S100 family, is associated with tumour proliferation, migration, and invasion. S100A11, functioning as a calcium-responsive scaffold, may enhance IGF-1Rβ-mediated regulation of cytoskeletal dynamics and motility. The aim of the current research is to identify and confirm this interaction and its subcellular localisation in several cancer types.
Methods:
Utilising LC–MS/MS data from IGF-1Rβ immunoprecipitates in HepG2 cells, which identified S100A11 as a potential protein partner, targeted validation studies were conducted to validate and characterise this connection. Analyses of protein expression and interactions were performed on a panel of human cancer cell lines. Endogenous IGF-1Rβ–S100A11 complexes were analysed using co-immunoprecipitation and subsequent Western blotting. Subcellular fractionation was utilised to determine the localisation of these complexes in membrane and nuclear compartments.
Results:
The nuclear localisation of IGF-1R was confirmed in HepG2, Hep3B, and Huh7 hepatocellular carcinoma cell lines via cellular fractionation and Western blot analysis, thereby establishing a basis for subsequent interactome studies. Proteomic profiling utilising LC–MS/MS identified numerous unique proteins linked to IGF-1R, with S100A11 selected for further study due to its established involvement in cancer cell migration and metastasis. Co-immunoprecipitation and immunoblotting confirmed a robust and specific physical interaction between IGF-1Rβ and S100A11 in HepG2 and RH30 cells. Subcellular fractionation demonstrated that the IGF-1Rβ–S100A11 complex is present in both the plasma membrane and nuclear compartments. The dual localisation indicates that the IGF-1Rβ/S100A11 axis operates as a novel non-canonical signalling link, potentially connecting IGF-1R-mediated growth signalling with S100A11-dependent pathways that influence cytoskeletal activity and tumour growth.
Conclusion:
This research identifies a new and functionally important relationship between IGF-1Rβ and S100A11, suggesting a possible oncogenic interaction that has significant implications for cancer growth. The observed dual localisation of the IGF-1Rβ–S100A11 complex at the plasma membrane and in the nucleus highlights its diverse signalling potential. The findings indicate that the IGF-1Rβ/S100A11 axis functions as a vital integrator of growth factor and calcium dependent pathways.
