The C-erbB-2 proto-oncogene encodes the production of a
cell surface receptor protein, with
tyrosine kinase activity. Over expression of this gene either due to gene amplification and/or increased transcription has been observed and has been correlated with poor prognosis in patients with Breast (10-33%) and ovarian (20-33%)
cancers. The very low levels of expression of C-erbB-2 by normal tissues makes this receptor a potential target for diagnosis and
therapy with
Monoclonal antibodies raised against its extracellular domain. One such
monoclonal antibody designated as CIBCgp185 of
IgG2a isotype has been generated in our laboratory using BT474
breast carcinoma cell line as immunogen. This
monoclonal antibody immunoprecipitated a 185 KD
glycoprotein. The specificity of this antibody was confirmed by the formation of a single discrete band and positive reaction with BT474
antigen in Western blot and Dot blot respectively. Flowcytometric analysis performed using various
cancer cell lines revealed that this
Monoclonal antibody exhibited high binding affinity with BT474 and SKBR3 cells whichoverexpresses C-erbB-2. By immunoperoxidase test, this antibody stained specifically the
tumor cell membrane in frozen tissue sections of breast and ovarian
tumors indicating overexpression of the C-erbB-2 product. All these results well correlated with those obtained using a control antibody ICR12, an anti-C-erbB-2 antibody. These studies clearly indicate that
Monoclonal antibody CIBCgp185 might prove useful to identify
tumors with over expression of C-erbB-2 which are often associated with poor prognosis and early recurrence.