Immunoinformatic-guided design of a polo-like kinase 1 (PLK1)-targeted multi-epitope vaccine with preliminary in vitro validation

Introduction Polo-like kinase 1 (PLK1) is a well-established oncogenic protein, as indicated by elevated levels of protein expression and function in a variety of tumor malignancies, and thus helps in metastasis of the disease. To target the PLK1, the study designed a cancer antigen that is capable of activating enhanced immune signaling pathways using an immunoinformatic approach. Methodology To achieve the study’s objective initially, the potential B- and T-cell epitopes were screened through IEDB resources. By analyzing immunological profiles, the highly antigenic, non-toxic and non-allergenic epitopes were screened and further utilized for vaccine design. Using appropriate linkers and adapters, the multi-epitope vaccine was constructed, and subsequent structural modelling and validation were analyzed. Following that, the immunogenic potential was analyzed through molecular docking, molecular dynamic simulations, and immune simulations. In silico cloning and preliminary in vitro validation using selected CTL epitopes were performed. Results Four highly antigenic B-cell, five CTL, and five HTL epitopes along with linkers and 50s ribosomal adjuvants were utilized for vaccine construction. The subsequent physicochemical characterization and structural validation revealed that the PLK1 vaccine is considered highly stable. The molecular interactions with innate receptors revealed that the PLK1 vaccine had high binding affinity with the TLR4 receptor (−402.83 kcal/mol) compared to TLR2. The investigations under physiological conditions exhibited that the PLK1 vaccine with TLR complexes maintained structurally stable conformations. The elevated level of IFN-gamma and IL-2 productions was observed in the immune simulation analysis. The final recombinant length of the optimized gene expression was observed to be 6,488 bps. A decrease in PLK1 transcript levels was observed in the SKBR3 cells after treatment with specific CTL epitopes. Discussion The enhanced immune profiles of the constructed PLK1 demonstrated a favourable predicted interaction with TLR4, suggesting a potential receptor recognition that may associated with Th1-mediated immune responses. Conclusion Overall, the PLK1 cancer antigen may act as a promising candidate in the context of cancer immunotherapy. Further, experimental validation in proper animal models is required to validate its immunogenic potential.