ABSTRACT
Paraffin-embedded, formalin-fixed tissue (PEFFT) specimens from a subset of breast cancer patients were analyzed by immunohistochemistry to determine whether or not the presence of P-glycoprotein identified chemotherapy resistance. Two antibodies, C219 (monoclonal) and Ab1 (polyclonal), demonstrated appropriate immunostaining. Retrospectively and prospectively, P-glycoprotein expression was determined from PEFFT of 20 breast cancer biopsies (19 patients with locally advanced or metastatic disease). Immunohistochemical staining was graded for number of positive cells (N0 to N4) and intensity (I0 to I3). The immunostaining N and I of both antibodies were similar. There was no correlation between N, (P = 0.13) or I, (P = 0.67) and chemotherapy response or between N, (P = 0.63) or I, (P = 0.89) and survival. Five patients had residual cancer at repeat biopsy after systemic chemotherapy for locally advanced disease. These specimens had similar N and I as the primary cancer. This assay accurately identifies P-glycoprotein expression in PEFFT and revealed no correlation between expression and chemotherapy response or survival.
Subject(s)
ATP Binding Cassette Transporter, Subfamily B, Member 1/analysis , Breast Neoplasms/chemistry , Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Breast Neoplasms/drug therapy , Breast Neoplasms/mortality , Breast Neoplasms/pathology , Drug Resistance, Multiple , Female , Humans , Immunohistochemistry , Paraffin Embedding , Survival Rate , Tissue FixationABSTRACT
A new method (Freeze-Transfer) is described for performing high-resolution immunocytochemistry for soluble cell proteins on frozen sections of biological tissues that involves thaw-mounting frozen tissue sections directly onto the surface of nitrocellulose thin films instead of directly onto glass slides. This technically straight-forward change in methodology resulted in chromogenic immunocytochemical assays for Her-2 and EGF receptors that were 1-2 orders of magnitude more sensitive while still fully utilizing the diagnostic resolving power of light microscopy. The effects of membrane pore size and surface chemistry on the resolution and intensity of Her-2 signal suggest that the enhanced sensitivity of Freeze-Transfer was caused by the cytologically coherent transfer of target molecules normally lost from cut surfaces of cells mounted on nonporous glass during assay.
