Purpose: To assess the effect of chromosome 17 copy number on HER-2/neu status determination in breast cancers. Experimental Design: HER-2/neu gene copy and chromosome 17 centromere numbers were evaluated on 893 breast carcinomas using double color fluorescence in situ hybridization (FISH). The net and chromosome 17 corrected (ratio) HER-2/neu copy numbers were compared and related to immunohistochemistry done according to the Food and Drug Administration (FDA)–approved scoring system (0, 1+, 2+, and 3+) as a first screening step in 584 cases. Results: When a ratio ≥2 was considered as criterion for FISH positivity, 49.3% (440 of 893) of cases showed amplification versus 56.2% (502 of 893) by using a net HER-2/neu gene copy number >4 as a alternative criterion; 14.8% (67 of 453) of cases having a ratio <2 had a net HER-2/neu gene copy number >4 and 1.1% (5 of 440) with a ratio ≥2 had a net HER-2/neu gene copy number <4. Among discordant cases, 88.8% (64 of 72) were polysomic (>2.25 chromosomes 17/cell) and among polysomic cases, 12.8% (40 of 312) of the low polysomic (2.26-3.75 chromosomes 17/cell) and 36.9% (24 of 65) of the highly polysomic (>3.75 chromosomes 17/cell) cases showed discordance. In cases with a ratio <2, polysomy 17 incidences were 85.7% (6 of 7) in IHC 3+, 42.4% (79 of 186) in IHC 2+, 33.3% (15 of 45) in IHC 1+, and 29.1% (16 of 55) in IHC 0. Conclusion: A net increase in HER-2/neu gene copy number consecutive to polysomy 17 in the absence of specific gene amplification might lead to a strong protein overexpression in a small subset of breast carcinomas. HER-2/neu status determination by FISH is dependent on the criterion considered for positivity in clinical practice.
Author(s): Singer, B. | Abstract: Abasic site (AP)-containing duplexes, in which the AP site was flanked by adenine (A) or cytosine (C) bases had been shown to be more stable with flanking A than with C bases [J. S gi, B. Hang and B. Singer (1999) Chem. Res. Toxicol. 12, 917-923]. In this work we investigated whether the smaller destabilization by an AP site, when the neighbors are A, is a general effect of the purine neighbors versus the pyrimidines. An AP site (x), flanked by symmetric doublet bases, was first incorporated opposite T into 15-mer duplexes. Duplex stability was markedly decreased by the AP site in all cases, as compared to the control duplexes. The largest destabilization was observed with the duplex containing a central -TTxTT- sequence in which the DTm was -19.4oC and the DDGo37 was -6.57 kcal/mol. Changing the central -TTxTT- to the -AAxAA- sequence resulted in a smaller destabilization (-17.3 oC and -5.65 kcal/mol), although the neighbors were AoT base pairs in both cases. Similarly, the AP site in -GGxGG- sequence proved to be less destabilizing (-13.9oC, -5.74 kcal/mol) than in the -CCxCC- sequence (-15.8oC, -7.39 kcal/mol) although G.C pairs flanked the AP site in both cases. The same differential destabilization was also observed with duplexes that contained an A or C opposite the AP site. The average stabilizing effect of the symmetric doublet purine neighbors of an AP site opposite a T, A or C was 3.2oC DTm and 1.3 kcal/mol DDGo37, as compared to the pyrimidine neighbors. The opposite G base reduced or eliminated the differential effect of the neighbors. Unrestrained molecular dynamics was used to evaluate the effect of the flanking sequences on structural features of the duplexes containing T opposite the AP site. Explicit solvent and the particle mesh Ewald method were applied for accurate representation of the electrostatic interactions. The duplexes with doublet pyrimidine neighbors showed a larger magnitude of curvature around the lesion site than did the duplexes wit
Galectin-1, a member of the beta-galactoside-binding galectin family, is a pleiotropic dimeric protein participating in a variety of normal and pathological processes, including cancer progression. Modulation of the interactions with the basement membrane glycoprotein laminin and induction of apoptosis in activated T lymphocytes are well-known functions of this galectin. In this study, the expression of galectin-1 was examined in 148 human primary prostate carcinoma samples. Immunohistochemical staining of paraffin sections of prostate tissues revealed that galectin-1 was not detected in normal, PIN (prostatic intraepithelial neoplasia) or carcinoma cells, but accumulated in the stroma and associated fibroblasts. Galectin-1 expression was significantly increased in the tumour-associated stroma compared with the non-neoplastic gland-associated stroma in 21.3% of the cases (Mantel-Haenszel test, p=0.001; Wilcoxon signed rank test, p<0.0001). Increased galectin-1 expression in the cancer-associated stroma compared to the normal gland-associated stroma (p=0.03) was identified by multivariate analysis as a strong independent predictor of prostate-specific antigen (PSA) recurrence, just after the pathological stage (p<0.0001). The association between accumulation of galectin-1 in the stroma of the malignant tissue and aggressiveness of the tumour adds weight to the body of evidence that identifies a role for galectin-1 in the acquisition of the invasive phenotype. In addition to modulating cancer cell interactions with laminin, galectin-1 accumulated around the cancer cells may act as an immunological shield by inducing activated T-cell apoptosis. This exciting hypothesis warrants further investigation.
