Relation between deletion of chromosome 1p36 and DNA ploidy in breast carcinoma: an interphase cytogenetic study

Numerical aberrations of chromosomes 1 and 7 by fluorescent in situ hybridization and DNA ploidy analysis in breast cancer

The goals of this study were to detect the numerical alterations of chromosomes 1 and 7 in breast cancer and to correlate the findings with DNA ploidy status as well as with parameters of prognostic significance. Fluorescence in situ hybridization (FISH) with centromeric probes for chromosomes 1 and 7 and cellular DNA content measurement by image analysis-based cytophotometry were applied on interface nuclei from fresh tissue imprints of 59 breast ductal carcinomas. Immunohistochemical stainings for estrogen receptor (ER), progesterone receptor (PR), HER-2, p53, and Ki67 were performed on paraffin tumor sections. The correlation between DNA ploidy and chromosomal aberrations revealed a significant association between aneuploidy and aneusomy for both chromosomes 1 (p=0.002) and 7 (p=0.00001), however, a number of diploid tumors were found to be aneusomic, especially for chromosome 1. Chromosome 7 polysomy was significantly associated with a higher incidence of axillary lymph node metastasis (p=0.05), poorly differentiated (grade III) tumors (p=0.03), negative ER and PR status (p=0.02 and 0.001, respectively), as well as p53 protein expression (p=0.05) and a higher Ki67 labeling index (p=0.004). Chromosome 1 aneusomy was only related with HER-2 protein overexpression (p=0.05). No association between chromosome alterations and tumor size was detected. In conclusion, the results of our study indicate that the detection of numerical aberrations of chromosomes 1 and 7 by FISH seems to be more sensitive than DNA ploidy status for the evaluation of abnormal cellular DNA and chromosome 7 aneusomy characterizes tumors with aggressive features and therefore might be a useful predictor of unfavorable biological behavior in breast cancer.

c-erbB-2 over-expression in amplified and non-amplified breast carcinoma samples

We investigated c-erbB-2 oncogene amplification and over-expression in 79 invasive breast carcinoma samples using fluorescence in situ hybridization (FISH) and immunohistochemistry, with the aim of studying relationships between neoplasms over-expressing c-erbB-2 with or without amplification and bio-pathological parameters used in clinical breast cancer. Nineteen samples showed amplification, and all of these were positive by immuno-histochemistry. Moderate or intense immunostaining was present in a further 22 samples without c-erbB-2 amplification and was not related to any increased number of c-erbB-2 signals: 15 samples exhibited chromosome 17 polysomy, 3 monosomy and 4 no FISH abnormalities. Thirty-eight samples were immunonegative: 18 exhibited chromosome 17 polysomy, 9 monosomy and 11 no alterations. Samples having c-erbB-2 over-expression associated with amplification showed DNA aneuploidy and hormonal receptor loss to a greater extent than those expressing c-erbB-2 without amplification or immunonegative samples (chi2 test, p = 0.007, 0.008 and 0.008, respectively). The proliferation rate, detected by Ag-NOR staining, was highest in amplified samples (Kruskal Wallis test, p = 0.009). Our results indicate that tumours showing both c-erbB-2 over-expression and amplification exhibit more aggressive biological characteristics than those with only over-expression or immunonegative tumours. Since both c-erbB-2 amplification and over-expression have been related to negative responses to chemotherapy and poor prognosis, these differences might have clinical implications. The combination of FISH and immuno-histochemistry may be helpful to achieve this aim.