Phospholipase-Cγ1 Signaling Protein Down-Regulation by Oligoclonal-VHHs based Immuno-Liposome: A Potent Metastasis Deterrent in HER2 Positive Breast Cancer Cells

The purpose of this study was to develop multivalent antibody constructs via grafting anti-HER2 antibodies, including Herceptin and oligoclonal-variable domain of heavy chain antibodies (VHHs), onto liposome membranes to enhance antibody activity and compare their effect on phospholipase C (PLC) signaling pathway with control.

In this experimental study, SKBR3 and BT-474 cell lines as HER2 positive and MCF10A cell line as normal cell were screened with anti-HER2 antibodies, including constructs of multivalent liposomal antibody developed with Herceptin and anti-HER2 oligoclonal-VHHs. To confirm the accuracy of the study, immunofluorescent assay, migration assay and immuno-liposome binding ability to HER2 were evaluated. Finally, the antibodies effect on PLCγ1 protein level was measured by an immunoassay method (ELISA).

In the present study, by using multivalent form of antibodies, we were able to significantly inhibit the PLCγ1 protein level. Interestingly, the results of migration assay, used for study the motility of different types of cell, shows correspondingly decreased number of immigrated cells in SKBR3 and BT-474 cell lines. Since MCF10A cells show no overexpression of HER2, as expected, the result did not show any change in PLCγ1 level. Moreover, immunofluorescent assay has confirmed high expression of HER2 in SKBR3 and BT-474 cell lines and low HER2 expression on MCF10A cell line. High binding of immuno-liposome to SKBR3 and BT-474 cells and low binding to MCF10A confirmed that in this study anti-HER2 antibodies have conserved binding ability to HER2 even after conjugation with liposome.

PLCγ1 protein levels did indeed decrease after treatment with immuno-liposome form of compounds in both two tested cell lines, verifying the inhibition ability of them. Moreover, an elevated antibody activity is associated with liposomes conjugation suggesting that immuno-liposome may be a potential target for enhancing the antibody activity.