Enhancing immune-mediated cancer cell engulfment through biophysical techniques: an in-silico investigation focusing on the peptide-mediated disruption of a C1q–gC1qR(p33) interaction

Tumor cells, being "self-modified," present altered antigens that could theoretically elicit immune recognition and autoantibody production. However, secreted gC1qR forms a protective shield by binding to C1q globular heads, potentially preventing its interaction with immune complexes on the tumor surface. The C1q-gC1qR interaction has been linked to promoting epithelial-mesenchymal transition through activation of Wnt/β-catenin and TGF-β signaling pathways, potentially driving cancer cell aggressiveness and migration. C1q, a key component of the complement system, mediates essential biological processes critical for host defense and autoimmunity prevention, as deficiencies correlate with increased autoimmune and infectious disorders. This work describes an in-silico method for identifying an interface-targeting peptide that may enhance immune-mediated cancer cell engulfment by competitively inhibiting a critical C1q-gC1qR interaction linked to immune evasion. Amino acids formed salt bridges and hydrogen bonds with peptide amino acids, according to interaction analysis using PDBePisa. The peptide's physicochemical and ADMET characteristics, including theoretical pI, aliphatic index, instability index, half-life, and molecular weight, were calculated. RMSF, RMSD, H-bonds, SASA, PCA, MM-PBSA, per-residue energy decomposition, and Rg were evaluated using molecular dynamics simulations. The computational results suggest that the peptide binds strongly to the C1q site, potentially blocking gC1qR and is predicted to facilitate C1q interaction with phagocyte receptor CD91, thereby potentially supporting cancer cell engulfment. All findings computationally predict that peptide satpdb11543-mediated disruption of the C1q-gC1qR interaction could be a viable strategy for enhancing immune-mediated engulfment of cancer cells.