Fusion Protein Improves Dendritic Cell Penetration, Raising Prospect of Efficient Cancer Vaccine


Get Permission

Immunotherapy with dendritic cells in combination with cytotoxic chemotherapy may eliminate minimal disease burden by generating cytotoxic T lymphocytes (CTLs). Improving the cytosolic bioavailability of tumor-specific antigens to improve access to HLA class I molecules would result in better generation of cytotoxic T lymphocytes. Numerous cell-penetrating domains (CPDs) are known to carry linked heterologous antigens through the plasma membrane into the intracellular compartment.

In a study reported in JAMA Surgery, Batchu and colleagues assessed whether fusing melanoma antigen family A,3 (MAGE-A3), a tumor-specific cancer-testis antigen, with a cell-penetrating domain would increase the cytosolic bioavailability of MAGE-A3. MAGE-3 was amplified by polymerase chain reaction and cloned in frame with a cell-penetrating domain (YARKARRQARR) at the amino-terminal end and hexahistidine at the carboxy-terminal end to generate CPD–MAGE-A3.

Western blot analysis with MAGE-A3 antibodies recognized both MAGE-A3 and CPD–MAGE-A3 proteins, whereas analysis with cell-penetrating domain antibodies recognized only CPD–MAGE-A3. Purified CPD–MAGE-A3 exhibited improved dendritic cell membrane penetration vs MAGE-A3 alone. The finding on flow cytometry of high expression of unique dendritic cell markers (CD80, CD83, CD86, and HLA-DR) on dendritic cells was consistent with a mature dendritic cell phenotype, indicating that pulsing with CPD–MAGE-A3 did not alter the repertoire of cell-surface antigens required for T-cell activation.

The investigators concluded, “We have demonstrated for the first time, to our knowledge, that cloning and purification of MAGE-A3 with CPD enhances its cytosolic bioavailability in [dendritic cells] without altering cell-surface antigens, potentially making it a more potent therapeutic cancer vaccine compared with existing MAGE-A3 protein and peptide vaccines.” ■

Batchu RB, et al: JAMA Surg 149:451-457, 2014.



Advertisement

Advertisement



Advertisement