H19 overexpression in breast adenocarcinoma stromal cells is associated with tumor values and steroid receptor status but independent of p53 and Ki-67 expression

Abstract

In a previous study we described the expression of the H19 gene by in situ hybridization (ISH) in normal breast and in benign or malignant breast tumors (Dugimont T, Curgy JJ, Wernert N, Delobelle A, Raes MB, Joubel A, Stehelin D, Coll J: Biol Cell 1995, 85:117-124). In the present work, 1) we extend the previous one to a statistically useful number of adenocarcinomas, including 10 subclasses, 2) we provide information on the precise ISH localization of the H19 RNA by using, on serial tissue sections, antibodies delineating specifically the stromal or the epithelial component of the breast, and 3) we consider relationships between the H19 gene expression and various clinicopathological information as tumor values (T0 to T4), grades, steroid receptors, lymph node status, and molecular features as the p53 gene product and the Ki-67/MIB1 protein, which is specific to proliferating cells. Data indicate that 1) in 72.5% of studied breast adenocarcinomas an overall H19 gene expression is increased when compared with healthy tissues, 2) the H19 gene is generally overexpressed in stromal cells (92.2%) and rarely in epithelial cells (2.9% only), 3) an up-regulation of the H19 gene is significantly correlated with the tumor values and the presence of both estrogen and progesterone receptors, and 4) at the cellular level, the H19 gene demonstrates an independent expression versus accumulation of both the p53 protein and the Ki-67/MIB-1 cell-cycle marker.

Figure 1.

Expression of the H19 gene in normal breast and in adenocarcinomas. A: Normal breast; epithelial (arrows) and mesenchymal (arrowheads) cells are labeled by the riboprobe. B and C: Epidermoid metaplastic carcinoma; H19 RNA was exclusively located in the epithelial cells. D to F: Invasive ductal carcinoma; H19 RNAs were exclusively located in the stromal compartment. B: Anti-KL-1-immunostaining; D: HPS coloration; E: anti-smooth-muscle-α-actin immunostaining; A, C, and F: ISH. In these two tumors, H19 transcripts accumulated at the epithelium/stroma boundaries, either in epithelial cells (C) or in stromal cells (F). Scale markers, 120 μm (A) and 600 μm (B to F).

Figure 2.

H19 gene overexpression compared with accumulations of p53 protein and Ki-67/MIB-1, a protein specific to the cell cycle. A to C: Invasive ductal carcinoma; H19 RNA was localized in epithelial and stromal cells. D to F: Invasive ductal carcinoma; H19 RNA was exclusively localized in the stroma. Overlapping of the actin immunolabeling and the H19 RNA patterns is seen. A: HPS coloration; B: anti-Ki-67/MIB-1 immunostaining; D: anti-smooth-muscle-α-actin immunostaining; E: anti-p53 immunostaining; C and F: ISH. B and C: No co-localization could be established between the overexpression of the H19 gene and the presence of the Ki-67/MIB-1 cell cycle marker. E and F: The H19 and p53 labelings do not overlap. Scale marker, 600 μm.