Kallistatin (KL) is a member of the serine proteinase inhibitor
(serpin) family regulating oxidative stress, vascular relaxation,
inflammation, angiogenesis, cell proliferation, and invasion. The
heparin-binding site of Kallistatin has an important role in the
interaction with LRP6 leading to the blockade of the Wnt signaling
pathway. In this study, we aimed to explore the structural basis of the
Kallistatin-LRP6E1E4 complex using in silico approaches and evaluating
the anti-proliferative, apoptotic, and cell cycle arrest activities of
Kallistatin in colon cancer lines. The molecular docking showed
Kallistatin could bind to the LRP6E3E4 much stronger than LRP6E1E2. The
Kallistatin-LRP6E1E2 and Kallistatin-LRP6E3E4 complexes were stable
during Molecular Dynamics (MD) simulation. The Molecular
Mechanics/Poisson-Boltzmann Surface Area (MM/PBSA) showed that the
Kallistatin-LRP6E3E4 has a higher binding affinity compared to
Kallistatin-LRP6E1E2. Kallistatin induced higher cytotoxicity and
apoptosis in HCT116 compared to the SW480 cell line. This
protein-induced cell-cycle arrest in both cell lines at the G1 phase.
The B-catenin, cyclin D1, and c-Myc expression levels were decreased in
response to treatment with Kallistatin in both cell lines while the LRP6
expression level was decreased in the HCT116 cell line. Kallistatin has
a greater effect on the HCT116 cell line compared to the SW480 cell
line. Kallistatin can be used as a cytotoxic and apoptotic-inducing
agent in colorectal cancer cell lines.
Keywords:
Kallistatin; LRP6 protein; apoptosis; cell cycle checkpoints; cell
survival; colorectal neoplasms; gene expression; human; molecular
docking; molecular dynamics simulation.