Amplifications of oncogene erbB-2 and chromosome 20q in breast cancer determined by differentially competitive polymerase chain reaction

MicroRNA-300 inhibits the growth of hepatocellular carcinoma cells by downregulating CREPT/Wnt/β-catenin signaling

A number of studies have demonstrated that altered expression levels of microRNA-300 (miR-300) are associated with tumor progression; however, little is understood regarding the role of miR-300 in hepatocellular carcinoma (HCC). The present study aimed to investigate the expression, biological function and potential regulatory mechanism of miR-300 in HCC. A miR-300 mimic and miR-300 inhibitor were transfected into liver cancer cells using RNAiMAX reagent. The expression levels of miR and mRNA were detected by reverse transcription-quantitative polymerase chain reaction. Protein expression levels were detected by western blot analysis. Cell growth was determined using Cell Counting Kit-8, a colony formation assay and cell cycle assay. miRNA targeting sites were analyzed using bioinformatics analysis and dual-luciferase reporter assay. The results revealed that miR-300 expression was significantly decreased in HCC tissues and cell lines. In vitro experiments demonstrated that overexpression of miR-300 could inhibit cell proliferation, colony formation and cell cycle progression of liver cancer cells. By contrast, inhibition of miR-300 was associated with increased rates of cell proliferation, colony formation and cell cycle progression. Notably, regulation of nuclear pre-mRNA domain-containing protein 1B (CREPT) was identified as a putative target gene of miR-300 by bioinformatics analysis. A luciferase reporter assay revealed that miR-300 directly targets the 3′-untranslated region of CREPT. Further data demonstrated that miR-300 can regulate CREPT expression levels in liver cancer cells. Notably, miR-300 was identified to regulate the Wnt/β-catenin signaling pathway in liver cancer cells. The restoration of CREPT expression partially reversed the antitumor effect of miR-300. In conclusion, the current results revealed a tumor suppressive role of miR-300 in HCC and indicated that the underlying mechanism was associated with a regulation of CREPT. The present study suggests that miR-300 and CREPT may serve as potential therapeutic targets for liver cancer.

Correlations of TOP2A gene aberrations and expression of topoisomerase IIα protein and TOP2A mRNA expression in primary breast cancer: a retrospective study of 86 cases using fluorescence in situ hybridization and immunohistochemistry

Our aim in this study was to assess the status of TOP2A gene aberrations (no change/amplification or deletion) and its correlations with topoisomerase IIα (Topo IIα) protein and TOP2A mRNA expression, respectively. TOP2A amplification, Topo IIα protein expression and TOP2A mRNA expression were assessed using samples of 86 cases of breast cancer by fluorescence in fluorescence in situ hybridization, quantitative real-time polymerase chain reaction and immunohistochemistry, respectively. Twenty two (22.57%) had amplification/deletion of TOP2A gene. Twenty eight (32.56%) tumor samples were 17q polysomy or monosomy. Topo IIα protein was expressed in 57 cases (66.27%, 57/86): 22 cases (38.62%, 22/57) and 35 cases (61.40%, 35/57) had amplification/deletion and no change of TOP2A gene, respectively. These three groups showed significant differences by one-way analysis of variance (P < 0.001). The average Ct values of TOP2A mRNA expression in the tumors with deletion, amplification and no change of TOP2A gene were 27.00, 27.33 and 31.66, respectively. We demonstrated that the TOP2A gene was amplified or deleted in breast cancer, with a significant correlation with high expressions of Topo IIα protein and TOP2A mRNA expression. Ki-67 expression index (mean = 14.9) decreased significantly in cases wherein TOP2A gene had no change and Her2/neu protein expression was weakly positive (0-1+, P < 0.001).

Molecular markers of breast axillary lymph node metastasis

In breast cancer, axillary lymph node status is one of the most important prognostic variables and a crucial component to the staging system. Several clinico-histopathological parameters are considered to be strong predictors of metastasis; however, they fail to accurately classify breast tumors according to their clinical behavior and to predict which patients will have disease recurrence. Methods based on genome-wide microarray analyses have been used to identify molecular markers with respect to the development of axillary lymph node metastasis. Most of these markers can be detected in the primary tumors, which can potentially lead to the ability to identify patients at the time of diagnosis who are at high risk for lymph node metastasis, allowing for early intervention and more suitable adjuvant treatments.

Laser capture microdissection-guided fluorescence in situ hybridization and flow cytometric cell cycle analysis of purified nuclei from paraffin sections

Laser capture microdissection (LCM) has recently been identified as a quick, simple, and effective method by which microdissection of complex tissue specimens for molecular analysis can be routinely performed. Assessment of gene copy number by fluorescence in situ hybridization (FISH) is useful for the analysis of molecular genetic alterations in cancer. Unfortunately, the application of FISH to paraffin sections of tumor specimens is fraught with technical difficulty and potential artifacts. Our results demonstrate that LCM-microdissected nuclei are suitable for FISH gene copy analysis. Amplification of genes in cancer specimens can be detected as easily in LCM-prepared nuclei as in fresh nuclei from cancer tissue specimens. Furthermore, contamination of tumor specimens by normal cells can make interpretation of flow cytometric cell cycle analysis difficult. Our results show that LCM-microdissected nuclei can also be used for flow cytometric cell cycle and ploidy analysis. LCM/FISH offers the advantages of multicolor FISH in a morphologically defined cell population, without the technical problems of FISH performed on paraffin sections. This technique should further simplify the methodology required to perform copy number analysis of tumor suppressor or protooncogenes in archived cancer specimens. The use of LCM specimens will also improve the specificity and simplify the interpretation of flow cytometric cell cycle and ploidy analysis of breast cancer specimens.

Quantitation of erbB-2 gene copy number in breast cancer by an improved polymerase chain reaction (PCR) technique, competitively differential PCR

A new method of measuring gene copy number in small samples of DNA was used to measure amplification of the erbB-2 gene and a reference gene in breast cancers. The method, termed 'competitively differential polymerase chain reaction' (CD-PCR), combines the advantages of two other techniques for measuring amplification by PCR, namely differential PCR (D-PCR) and competitive PCR (C-PCR). The CD-PCR methodology was evaluated for sensitivity and specificity by comparing amplification measured by CD-PCR with that obtained by fluorescence in situ hybridization (FISH), C-PCR, and Southern blotting analysis. CD-PCR analysis proved to be an accurate predictor of amplification. CD-PCR also overcomes the problems involved in variation of PCR efficiencies and DNA concentrations in tumor samples, and the problems caused by the plateau effect in PCR.

Cyclin D1 gene amplification and overexpression are present in ductal carcinoma in situ of the breast

Cyclin D1 (CCND1) amplification is found in 10-15 per cent of invasive breast carcinomas, but it is not well established whether this gene alteration also occurs in the precursor of invasive breast carcinoma, ductal carcinoma in situ (DCIS). By Southern blot analysis, cyclin D1 gene amplification was detected in 10 per cent (3/32) of DCIS cases. In addition, 15 cases of DCIS were analysed using bright field in situ hybridization (BRISH), of which 11 had already been analysed by Southern blotting. One additional case with gene amplification was found by BRISH. The use of BRISH for the detection of gene amplification is shown to be a novel and reliable in situ method on paraffin-embedded tissue sections. By immunohistochemistry, 147 cases of DCIS were analysed for the expression of cyclin D1. Cyclin D1 overexpression was found in 9 per cent of well-differentiated, 29 per cent of intermediately differentiated, and 19 per cent of poorly differentiated DCIS. No statistically significant association was found between cyclin D1 overexpression and the differentiation grade of DCIS, although 90 per cent of the cases that show overexpression are classified as intermediately and poorly differentiated. An association was found between cyclin D1 overexpression and oestrogen receptor positivity. Cyclin D1 overexpression was found in all four cases with cyclin D1 gene amplification, but was also found in 30 per cent (8/27) of cases without detectable gene amplification. It is concluded that cyclin D1 gene amplification is an early event in the development of breast carcinoma and occurs in poorly differentiated DCIS. Cyclin D1 protein overexpression is also present in tumours without cyclin D1 gene amplification and is seen predominantly in DCIS of intermediately and poorly differentiated histological type and oestrogen receptor positivity.

Novel approach to quantitative polymerase chain reaction using real-time detection: application to the detection of gene amplification in breast cancer

Gene amplification is a common event in the progression of human cancers, and amplified oncogenes have been shown to have diagnostic, prognostic and therapeutic relevance. A kinetic quantitative polymerase-chain-reaction (PCR) method, based on fluorescent TaqMan methodology and a new instrument (ABI Prism 7700 Sequence Detection System) capable of measuring fluorescence in real-time, was used to quantify gene amplification in tumor DNA. Reactions are characterized by the point during cycling when PCR amplification is still in the exponential phase, rather than the amount of PCR product accumulated after a fixed number of cycles. None of the reaction components is limited during the exponential phase, meaning that values are highly reproducible in reactions starting with the same copy number. This greatly improves the precision of DNA quantification. Moreover, real-time PCR does not require post-PCR sample handling, thereby preventing potential PCR-product carry-over contamination; it possesses a wide dynamic range of quantification and results in much faster and higher sample throughput. The real-time PCR method, was used to develop and validate a simple and rapid assay for the detection and quantification of the 3 most frequently amplified genes (myc, ccndl and erbB2) in breast tumors. Extra copies of myc, ccndl and erbB2 were observed in 10, 23 and 15%, respectively, of 108 breast-tumor DNA; the largest observed numbers of gene copies were 4.6, 18.6 and 15.1, respectively. These results correlated well with those of Southern blotting. The use of this new semi-automated technique will make molecular analysis of human cancers simpler and more reliable, and should find broad applications in clinical and research settings.

Determination of copy number of rRNA genes in Pneumocystis carinii f. sp. hominis

Differential PCR was performed to determine the copy number of rRNA genes in Pneumocystis carinii f. sp. hominis. Two different reference genes, thymidylate synthase (TS) and beta-tubulin (BTU) genes, were used. Primers for the internal transcribed spacer (ITS) region of nuclear rRNA genes and either the TS or BTU gene were mixed together to perform PCR on seven different bronchoalveolar lavage specimens from patients with P. carinii pneumonia. The radioactivity derived from the incorporated radioactive nucleotides of each PCR product band was then used to calculate the copy number of the ITS relative to that of the TS or BTU gene. The copy number ratio between the ITS and the TS gene was determined to be 0.8, and that between the ITS and the BTU gene was also 0.8. These results suggest that the ITS has the same copy number as the TS or BTU gene. Since the copy number of the TS or BTU gene is presumed to be 1, the results also suggest that P. carinii f. sp. hominis has only one copy of the ITS and thus one copy of the nuclear rRNA genes. Therefore, two types of ITS sequences derived from a specimen would indicate that the patient is infected by two types of P. carinii f. sp. hominis.

Ductal carcinoma in situ of the breast: histological classification and genetic alterations

Ductal carcinoma in situ (DCIS) of the breast represents a proliferation of malignant epithelial cells within the ducts and lobules of the breast, without invasion through the basement membrane. It is believed that all invasive carcinomas are preceded by DCIS; however, it is not known what proportion of patients with DCIS will develop invasive carcinoma and after what interval. DCIS is heterogeneous with respect to its clinical presentation, mammographic abnormalities, histology and biology. The risk of progression to invasive carcinoma depends on the histologic type of DCIS and the size of the lesion; in the future, the analysis of the genetic alterations may also help in predicting the risk of progression to invasive breast cancer. As the risk of progression to invasive breast cancer (and the development of metastases) greatly influences the choice of treatment for DCIS, it is of importance to be able to make a reliable estimate of this risk of progression. In this chapter, the histologic classification of DCIS and the genetic alterations that have been found to date are discussed.