Liver tumor-initiating cells initiate the formation of a stiff cancer stem cell microenvironment niche by secreting LOX.

Accumulating evidence has shown that the traits of tumor-initiating cells (TICs) are controlled by the microenvironment niches (MENs), but the composition and remodeling mechanisms of the MENs of TICs are poorly defined. Here, we report that the voltage-gated calcium channel α2δ1 subunit-positive TICs of hepatocellular carcinoma (HCC) specifically secret lysyl oxidase (LOX), which leads to the cross-linking of collagen, forming a stiff extracellular matrix (ECM) that is sufficient to drive the formation of TICs with a stiff mechanical trait and is subsequently required for the maintenance the properties of HCC TICs. Furthermore, the cross-linked collagen results in the upregulation of integrin α7 (ITGA7), increased phosphorylation of FAK and extracellular signal-regulated kinase 1/2 (ERK1/2). Inhibition of ITGA7 abolishes all the effects of cross-linked collagen mediated by LOX. Hence, the α2δ1+ HCC TICs initiate ECM remodeling by secreting LOX to create a stiff MEN of TIC with cross-linked collagen, which drives the acquisition and subsequent maintenance of the properties of HCC TICs through ITGA7-FAK-ERK1/2 signaling pathway.