Integrin β4 reduces DNA damage-induced p53 activation in colorectal cancer

Abstract

Integrin contributes to the maintenance of cell adhesion. In turn, cell adhesion triggers certain integrin signaling cascades, and influences cell biological behavior. In the present study, we explored the role and mechanism of integrin β4 in the DNA damage response in colorectal cancer (CRC) using a three-dimensional (3D) cell culture model. Under 3D culture condition, dispersed CRC cells automatically formed multicellular spheroids, which consisted of layers of cells with cell junctions commonly distributed. The expression level of integrin β4 in HCT116 3D cultures was slightly higher compared with two-dimensional (2D) cultures, while the expression level in LoVo 3D cultures was similar to or slightly lower than that in 2D cultures. Knockdown of integrin β4 by lentiviral delivery of shRNA did not markedly change the architectural formation of 3D cultures under an inverted microscope or transmission electron microscope. Platinum increased p53 and p-p53 (ser15) in a time-dependent manner in 3D cultures. Knockdown of integrin β4 increased sensitivity to cisplatin (CDDP) in 3D cultures. Under 3D culture condition, knockdown of integrin β4 did not detectably change the basal p53 protein level but increased p53 and p-p53 (ser15) protein accumulation induced by platinum. Integrin β4 knockdown did not detectably change p53 protein level in HCT116 2D cultures with or without CDDP treatment. Knockdown of wild-type p53 decreased sensitivity to platinum in 3D cultures. Since it has been proven that platinum damages DNA to kill cells and p53 plays a key role in the DNA damage response, our results indicated that integrin β4 reduced DNA damage-induced p53 activation to decrease chemosensitivity in CRC. This may be due to integrin β4 activation in 3D cultures.