engleski

Preserved nuclear localization of p62c-myc oncoprotein in freshly frozen paraffin embedded breast carcinoma tissues

Normally, oncoprotin p62c-myc is localized in the cell nucleus. However, in freshly frozen sections, immunohistochemical localization of this antigen has been hampered by destruction of cell and tissue architecture during cryosectioning. In paraffin embedded sections, we have shown previously that the commonly observed cytoplasmic stining for p62c-myc resulted from inadequate fixation. We found that a more adequate fixsation procedure included treatment with cold acetone (-20oC) followed by methyl benzoate and xylene (AMeX ; Pavelić et al., J. Exp. Path., in press). We wished to eliminate artifacts of cryosectioning and embedding in paraffin. In this study we evaluated the AMex procedure in immunohistochemical localization of p62c-myc in infiltrating ductal breast carcinoma tissue freshly frozen, AMeX treated and then embedded in paraffin (FF-AMex). To delineate distribution and intensity of staining for p62c-myc in tumor cells, we used the monoclonal antibody 155-11C7 raised against a synthetic myc peptide (Microbiological Associated, Bethesda, MD). We assessed the intensity of immunostaining and percentage of positive tumor cells and observed more intense staining of p62c-myc in freshly frozen section than in FF-AMeX sections, but tissue and cell architecture were much better preserved in FF-AMeX. Our results show that AMeX procedure in previously frozen tissues resulted in reproducible nuclear immunostaining for p62c-myc. This finding is important because tissues often kept frozen for steroid receptor analysis can be also used for immunohistochemical localization of oncoproteins.

oncoprotein p62c-myc; immunohistochemistry

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