Loss of heterozygosity at the TP53 gene: independent occurrence from genetic instability events in node-negative breast cancer

KIF11 as a potential cancer prognostic marker promotes tumorigenesis in children with Wilms tumor

Emerging evidence suggests that KIF11 could play a pivotal role in cancer cell proliferation; however, its biological functions and molecular mechanisms in Wilms tumor (WT) cells are largely unknown. The aim of this study was to evaluate the clinical significance and therapeutic potential of KIF11 proteins in WT. KIF11 expression in WT tissues and adjacent nontumor tissues was determined using qRT-PCR, Western blotting, immunohistochemistry (IHC) and bioinformatics. The function of KIF11 protein was determined by its correlation with tumor cell growth, angiogenesis, and apoptosis using IHC and lentiviral vector-mediated KIF11 depletion. KIF11 expression was upregulated in WT tissues and was associated with WT clinical outcomes. Tumor KIF11 expression was significantly associated with the Ki67 proliferation index. CCK-8, flow-cytometric analysis, and Western blotting revealed that KIF11 knockdown significantly inhibited WT cell growth. Functional studies have indicated that increased KIF11 expression is significantly correlated with vascular endothelial growth factor (VEGF) expression and intratumoral microvessel density. We further confirmed that downregulated expression of KIF11 promoted cell apoptosis and significantly increased Bcl-2 and Bax expression. Our findings demonstrate that KIF11 plays a role in promoting the development of human WT and can serve as a potential molecular marker for the treatment of WT.

Genomic Changes in Normal Breast Tissue in Women at Normal Risk or at High Risk for Breast Cancer

Sporadic breast cancer develops through the accumulation of molecular abnormalities in normal breast tissue, resulting from exposure to estrogens and other carcinogens beginning at adolescence and continuing throughout life. These molecular changes may take a variety of forms, including numerical and structural chromosomal abnormalities, epigenetic changes, and gene expression alterations. To characterize these abnormalities, a review of the literature has been conducted to define the molecular changes in each of the above major genomic categories in normal breast tissue considered to be either at normal risk or at high risk for sporadic breast cancer. This review indicates that normal risk breast tissues (such as reduction mammoplasty) contain evidence of early breast carcinogenesis including loss of heterozygosity, DNA methylation of tumor suppressor and other genes, and telomere shortening. In normal tissues at high risk for breast cancer (such as normal breast tissue adjacent to breast cancer or the contralateral breast), these changes persist, and are increased and accompanied by aneuploidy, increased genomic instability, a wide range of gene expression differences, development of large cancerized fields, and increased proliferation. These changes are consistent with early and long-standing exposure to carcinogens, especially estrogens. A model for the breast carcinogenic pathway in normal risk and high-risk breast tissues is proposed. These findings should clarify our understanding of breast carcinogenesis in normal breast tissue and promote development of improved methods for risk assessment and breast cancer prevention in women.

Concurrent overexpression of p53 and c-erbB-2 correlates with accelerated cycling and concomitant poor prognosis in node-negative breast cancer

Simultaneous overexpression of c-erbB-2 and p53 has been reported to be prognostically unfavorable in breast cancer. Herein, we show that concurrent overexpression of these 2 proteins is associated with a marked reduction in the relative fraction of cells in G(1) phase of the cell cycle, indicating an accelerated cell cycle progression. Using an immunohistochemical approach, we examined 261 cases of node-negative infiltrating ductal carcinomas of the breast with respect to c-erbB-2 and p53 expression and to the proliferative activity measured by the Ki-67 index. By means of a novel monoclonal antibody, Ki-S2, which exclusively recognizes proliferating cells in the S, G(2), and M phases of the reproductive cycle, we were further able to calculate the relative fraction of the cells having passed the restriction point at the G(1)/S boundary, thus defining a cycling ratio (CR). The results were correlated with clinical outcome; median follow-up time was 96 months. Tumors that simultaneously overexpressed c-erbB-2 and p53 had a high median CR and followed an unfavorable course. However, increased CRs were also observed independently of c-erbB-2 and p53 overexpression, suggesting that other molecular mechanisms may contribute to acceleration of cell cycle progression. In a multivariate analysis that included patient age, tumor size, hormone receptor status, c-erbB-2 and p53 expression, and the Ki-67 index, CR emerged as the most significant independent predictor of overall and disease-free survival (P <.0001). It is concluded that the CR is a gauge of cell cycle deregulation and therefore may be a powerful indicator of the biologic behavior of cancers. HUM PATHOL 32:311-319.

Biophenotypes and survival of BRCA1 and TP53 deleted breast cancer in young women

The aim of this study was to examine the loss of heterozygosity (LOH) of BRCA1 (17q21) and TP53 (17p13.1) in early-onset breast cancer patients; to correlate biopathological characteristics with molecular alterations; and to investigate the survival of LOH-related cancers. BRCA1 and TP53 LOH were evaluated in 78 early-onset breast cancers (< or = 40 years, Group 1) and 80 patients with age > 55 years (Group 2). Cases were characterized for multiple biological markers (ER, PR, proliferation index (PI), NEU and p53). LOH was carried out on microdissected paraffin embedded tissues; microsatellites D17S855 (BRCA1) and D17S786 (TP53) were amplified by fluorescent PCR and analyzed by an automated DNA sequencer. Early-onset breast cancers showed a higher frequency of ductal histotype (89.7% vs. 56.3% p < 0.001), node-positive (53.8% vs. 38.7%), larger size (p = 0.017), higher mitotic rate (p = 0.025), higher nuclear and final grade (p = 0.01 and p = 0.001, respectively). D17S855 LOH was 32.8% in group 1 vs. 21% in group 2; D17S786 LOH was 50.7% vs. 31.3% (p = 0.03), respectively. BRCA1 LOH was correlated with higher PI (p = 0.032) and higher p53 expression (p < 0.001) in group 1 and with higher NEU expression (p = 0.028) in group 2. TP53 LOH was correlated with p53 overexpression (p = 0.03) in group 1. A worse clinical outcome in early-onset LOH related cancers emerged from follow-up data: TP53 and BRCA1 LOH were associated with a shorter relapse free interval (RFI) (p = 0.03) and a poorer overall survival (OS) (p = 0.04), respectively. This study underlines different biological profiles in the two age groups investigated, probably reflecting different mechanisms of carcinogenesis. In accordance with adverse histopathological features in early-onset patients, LOH-related cancers have an unfavorable prognosis.

Prognostic value of genomic alterations in minimal residual cancer cells purified from the blood of breast cancer patients

The prognostic value of disseminated tumour cells derived from 353 breast cancer patients was evaluated. Disseminated tumour cells were purified from blood using a newly established method and nucleic acids were subsequently isolated. We investigated genomic imbalances (GI) such as mutation, amplification and loss of heterozygosity of 13 tumour suppressor genes and 2 proto-oncogenes using DNA from isolated minimal residual cancer cells. Significant correlations were found between genomic alterations of the DCC - and c-erbB-2 genes in disseminated breast cancer cells and actuarial relapse-free survival. Furthermore, increasing numbers of genomic imbalances measured in disseminated tumour cells were significantly associated with worse prognosis of recurrent disease. Logistic regression and Cox multivariate analysis led to the identification of genomic imbalances as an independent prognostic factor. Determination of disseminated tumour cells by genotyping of oncogenes and tumour suppressor genes seems not only to be a useful adjunct in follow up of carcinoma patients but provides also valuable additional individualized prognostic and predictive information in breast cancer patients beyond the TNM system.

Genetic alterations in early-onset invasive breast carcinomas: correlation of c-erbB-2 amplification detected by fluorescence in situ hybridization with p53 accumulation and tumor phenotype

p53 tumor-suppressor gene mutation and p53 protein over-expression have been reported with higher frequency in early-onset breast carcinomas (EOBC). Given the role attributed to normal p53 protein in DNA-repair mechanisms, other somatic genomic alterations would be expected to be associated with this abnormality. Amplification of the c-erbB-2 (HER-2/neu) oncogene and over-expression of the corresponding p185erbB-2 protein have been linked to prognosis and response to therapy in breast cancer. In a retrospective study of 62 formalin-fixed paraffin-embedded invasive EOBC (diagnosed at 35 years or less), the amplification status of the c-erbB-2 gene detected by fluorescence in situ hybridization (FISH) using a unique sequence probe was compared with p53 protein accumulation measured by immunohistochemistry (IHC) and phenotypic features. p185erbB2-protein expression was also detected by immunohistochemistry, together with estrogen-receptor (ER) and progesterone-receptor (PR) expression. The data for a sub-set of 33 node-negative EOBC cases were compared with 70 node-negative tumors diagnosed in women above 36 years of age. Compared with node-negative BC in older women, node-negative EOBC was significantly more likely to feature high grade, high proliferation rate, negative ER and/or PR and p53 over-expression (p < 0.05). A trend toward a higher incidence of c-erbB-2 amplification in EOBC (21% vs. 9%) reached near-significance (p = 0.07). In EOBC, c-erbB-2 amplification and p53 over-expression were not associated with high tumor grade or high cell-proliferation rate, in contrast to the significant associations of these markers in tumors in older women. Abnormalities in tumor markers, including c-erbB-2 gene amplification and p53-protein over-expression, occur at different rates in women with EOBC as compared with BC developing in older women. This finding may reflect a different pathogenesis for EOBC, and warrants further investigation.

Frequent allelic losses at 11q24.1-q25 in young women with breast cancer: association with poor survival

Previous studies have demonstrated that the pathological features of breast cancer are more aggressive in younger women than in their older counterparts, and that young age may be an independent marker for adverse prognosis. These findings have raised the question whether these differences are also present at the molecular level. In order to characterize the genetic alterations associated with early-onset breast cancer, 102 cases selected for age under 37 at diagnosis were examined for loss of heterozygosity (LOH) at nine different loci on chromosomes 11, 13 and 17. Ninety cases (88%), exhibited LOH for at least one marker. The D17S855 marker, intragenic in the BRCA1 gene, showed a high proportion of LOH (63%), whereas the intragenic marker for the TP53 gene, HP53, exhibited LOH in 43% of the cases. On chromosome 11, frequencies of LOH peaked at the D11S969 and D11S387 markers, which expressed LOH in 53% and 48% of the informative cases, whereas D11S1818, which is proximate to the ATM gene, exhibited an LOH frequency of 24%. A statistically significant correlation was found between LOH at the D11S387 marker and poor survival (P = 0.028). No such correlation was found for the adjacent D11S969 marker, located approximately 500 kb centromeric to D11S387. We conclude that one or more as yet unidentified genes, situated in chromosome bands 11q24.1-q25, could be involved in the initiation and/or progression of breast cancer in younger women.

Correlation between p53, c-erbB-2, and topoisomerase II alpha expression, DNA ploidy, hormonal receptor status and proliferation in 356 node-negative breast carcinomas: prognostic implications

Various new prognostic indicators have been identified for mammary carcinomas, but the issue of their significance remains unsettled. The prognostic impact of p53, c-erbB-2, and topoisomerase II alpha expression was investigated in relation to standard prognostic factors for carcinomas of the breast and to the tumour cell growth fraction. Paraffin-embedded specimens of 356 node-negative infiltrating ductal carcinomas were stained immunohistochemically using a polyclonal antiserum to c-erbB-2, and the monoclonal antibodies DO-1 (p53), Ki-S4 (topoisomerase II alpha), and Ki-S5 (Ki-67). The patients were followed for a median duration of 99 months. Both p53 and c-erbB-2 were significantly associated with high tumour grade, large tumour size, DNA aneuploidy, lack of steroid hormone receptors, young age, and increased topoisomerase II alpha and Ki-67 expression levels. The correlation of p53 and c-erbB-2 was not significant. Topoisomerase II alpha and Ki-67 scores closely paralleled each other, indicating that both reflect the proliferative activity of tumour cells. A univariate analysis of overall (OS), specific (SS), and disease-free survival (DFS) revealed all the above-mentioned parameters to be statistically significant except patient age, which was relevant only to overall survival. Multivariate analysis with inclusion of all covariates selected tumour size and proliferation (topoisomerase II alpha and Ki-67) indices as independent predictors of survival in all three models. No additional information was gained by p53 or c-erbB-2. It is concluded that the proliferative activity, as assessed by topoisomerase II alpha or Ki-67 immunostaining, is the most useful indicator of breast cancer prognosis, except for tumour size.