Chromogranin A and B gene expression in carcinomas of the breast. Correlation of immunocytochemical, immunoblot, and hybridization analyses.

Chromogranins (Cg) are regarded as specific neuroendocrine (NE) markers in cells and tumors. Expression of CgA and CgB genes has been demonstrated by correlative immunocytochemical, immunoblotting, in situ hybridization, and Northern blot procedures in seven argyrophilic breast carcinomas, while eight control cases of ductal carcinomas, not otherwise specified, were negative. A high degree of correlation was observed between the various techniques revealing CgA and/or CgB gene expression at different levels; minor discrepancies might be related to tumor heterogeneity or to technical factors. The present study, confirming previous investigations, establishes NE differentiation in a group of human breast cancers. The identification of this type of tumors, especially by testing chromogranin(s) production, appears to be of both biologic and clinical interest.