Quantitative Analysis of HER-2 Expression

In order to quantitate HER-2 expression values, we performed well-based reverse phase protein array (RPPA) as previously reported [13 (link)]. Briefly, extracted proteins (400 ng) were applied onto 96-well Multi-Spot™ plates (Meso Scale Discovery, Gaithersburg, MD, MA2400 96 HB Plate), the plate was allowed to dry at RT, and if needed, further incubated at 37°C for 30 min. The antigen-coated plates were pre-incubated with 5% BSA in PBST for 60 min at RT before primary antibody incubation. Anti-HER-2 (DAKO) and anti-GAPDH (Calbiochem) were diluted 1:1000 and 1:5000 with 5% BSA in PBST, followed overnight incubation at 4°C. After washing with PBST, the plates were incubated for 90 min with goat anti-rabbit or mouse SULFO-TAG™ antibodies (Meso Scale Discovery) at a dilution of 1:2000. The plates were washed three times with PBST. MSD-T read buffer was added to the plates and signals were detected using Sector Imager 2400 reader (Meso Scale Discovery). BSA coated wells were included on each plate as a control of non-specific binding. HER-2 expression signal was normalized with the value of GAPDH.