Immunohistochemical Staining of Tumor Tissue

Standard IHC protocol was followed to stain the tumor tissue samples using the mouse monoclonal antibody against hNIS (human Sodium Iodide Symporter) (Abcam, ab17795), ER (Estrogen Receptor) (Abcam, ab16660, ab288). Briefly, 5 µm sized paraffin embedded tissue sections were de-paraffinized with xylene and endogenous peroxidase activity was quenched with 3% H₂O₂ in methanol for 30 minutes in the dark. Tissue sections were dehydrated through graded alcohols and subjected to antigen retrieval using 10mM sodium citrate. Sections were washed with TBST (Tris Borate Saline Tween-20) and then blocked with 5% BSA (Bovine Serum Albumin) for one hour. Slides were incubated with the respective mouse monoclonal primary antibody diluted with TBS. Slides were then washed for 5 minutes in TBST and incubated for 1 hour with the respective HRP (Horse Raddish Peroxidase) conjugated anti-mouse secondary antibody diluted with TBS in a ratio of 1∶200. After washing, slides were incubated with DAB (3,3′-diaminobenzidine tetrahydrochloride) (Sigma) and immediately washed under tap water after color development. Slides were then counter stained with hematoxylin. Slides were mounted with DPX (dibutyl phthalate xylene) and were then observed under a light microscope (Carl Zeiss).