ABSTRACT
BACKGROUND: A major challenge of cancer research is to identify key molecules which are responsible for the development of the malignant metastatic phenotype, the major cause of cancer death. METHODS: Four subtracted cDNA libraries were constructed representing mRNAs differentially expressed between benign and malignant human breast tumour cells and between micro-dissected breast carcinoma in situ and invasive carcinoma. Hundreds of differentially expressed cDNAs from the libraries were micro-arrayed and screened with mRNAs from human breast tumor cell lines and clinical specimens. Gene products were further examined by RT-PCR and correlated with clinical data. RESULTS: The combination of subtractive hybridisation and microarray analysis has identified a panel of 15 cDNAs which shows strong correlations with estrogen receptor status, malignancy or relapse. This panel included S100P, which was associated with aneuploidy in cell lines and relapse/death in patients, and AGR2 which was associated with estrogen receptor and with patient relapse. X-box binding protein-1 is also an estrogen-dependent gene and is associated with better survival for breast cancer patients. CONCLUSIONS: The combination of subtracted cDNA libraries and microarray analysis has thus identified potential diagnostic/prognostic biomarkers and targets for cancer therapy, which have not been identified from common prognostic gene signatures.
Subject(s)
Breast Neoplasms/genetics , Breast Neoplasms/pathology , Aged , Aged, 80 and over , Breast Neoplasms/metabolism , Cell Line , Disease Progression , Female , Gene Expression Profiling , Humans , Microarray Analysis , Middle Aged , Molecular Sequence Data , Neoplasm Staging , Nucleic Acid HybridizationABSTRACT
Elevated levels of the calcium-binding protein S100A4 have been causally linked to the metastatic spread of breast cancer cells in several in vitro and in vivo model systems and, more recently, correlated with patient death in a series of human breast cancer specimens. In transgenic mice expressing MMTV-neu transgenes in mammary gland, additional expression of S100A4 transgenes results in an enhanced metastatic capability. Despite this phenotypic difference arising from elevated S100A4, it is now shown that the primary breast tumours in all mice examined are histopathologically very similar and resemble those human tumours associated with elevated c-erbB-2. Using a panel of genes identified by suppression subtractive hybridization of cDNAs from individual primary tumours and a metastasis, some cDNAs were found to exhibit a differential pattern of expression associated with the expression of S100A4 protein (including osteopontin, S100A9, claudin 2 and several Expressed Sequence Tags sequences). Whilst confirming differential expression of these genes, it was demonstrated that individual primary tumours of matched transgenic status, histology and grade exhibit some degree of heterogeneity at the mRNA level by reverse Northern and Northern hybridizations. This intertumour heterogeneity of mRNA level was confirmed by cDNA array analysis and suggests that even in a transgenic model, which exhibits far less variation than the human disease, there may be multiple mechanisms of disease progression.
Subject(s)
Disease Models, Animal , Lung Neoplasms/secondary , Mammary Neoplasms, Experimental/metabolism , Receptor, ErbB-2/metabolism , S100 Proteins/metabolism , Animals , Blotting, Northern , Breast Neoplasms/metabolism , Breast Neoplasms/pathology , DNA, Complementary/genetics , DNA, Neoplasm/genetics , Female , Gene Expression , Humans , Lung Neoplasms/genetics , Lung Neoplasms/metabolism , Mammary Neoplasms, Experimental/genetics , Mammary Neoplasms, Experimental/pathology , Mammary Tumor Virus, Mouse , Mice , Mice, Transgenic , Neoplasm Proteins/metabolism , S100 Calcium-Binding Protein A4ABSTRACT
Hyperplasia of usual type (HUT) may be an early precursor of breast carcinoma and has been shown to contain molecular and genetic abnormalities previously seen in more advanced breast lesions, such as allelic imbalance (AI) and coexpression of estrogen receptor-alpha (ER) and the proliferation marker Ki67. We have examined hyperplastic and other areas from within radial scar (RS) for such abnormalities, to explore whether such regions of RS are similar at the molecular and genetic level to histologically similar lesions found independent of RS. Abnormal expression of ER and Ki67 in hyperplastic foci and other histologically distinct areas within RS was detected by dual-label immunofluorescence. Subtle differences in expression patterns were seen compared to similar lesions outside RS, with a lower overall level of ER overexpression in HUT within RS (P = 0.0012) and less evidence of the abnormal ER association with Ki67 (P = 0.004). AI of chromosome 16q and 8p was detected in RS, indicating that at least some areas of RS are clonal and neoplastic, but no clear relationship to ER dysregulation was found. Different genetic losses seen in microdissected areas of the same RS indicated clonal differences between these areas. The role of RS as a marker of malignancy and relative risk of breast cancer remains uncertain. Nonetheless, here we provide evidence that some molecular and genetic changes that occur to a greater degree in breast cancer and some premalignant breast lesions are present in a minority of RS.
Subject(s)
Breast Neoplasms/genetics , Breast/pathology , Loss of Heterozygosity , Precancerous Conditions/genetics , Breast/metabolism , Breast Neoplasms/metabolism , Breast Neoplasms/pathology , Chromosome Aberrations , Chromosomes, Human, Pair 16 , Chromosomes, Human, Pair 8 , DNA, Neoplasm/analysis , Female , Fluorescent Antibody Technique , Humans , Hyperplasia/pathology , Ki-67 Antigen/metabolism , Polymerase Chain Reaction , Precancerous Conditions/metabolism , Precancerous Conditions/pathology , Receptors, Estrogen/metabolismABSTRACT
BACKGROUND: To date, research in the role of angiogenesis in cancer has focused mainly on invasive diseases. Measurement of the intra-tumoural microvessel density (MVD) has also been found to be an independent prognostic marker. More recently, natural angiogenic inhibitors and pharmacological drugs capable of suppressing specific stages of neovascularisation have been reported. METHODS: This review article concentrates on those angiogenesis-related findings in pre-invasive disease. RESULTS AND CONCLUSION: The study of angiogenesis in early and preneoplastic lesions is still at a preliminary stage. Current work provides indirect evidence, either from clinical or experimental studies only, most of which have used animal models. The use of the MVD as a marker of potential tumour invasion in pre-neoplastic disease is an attractive proposition. However, its prognostic values remain to be evaluated. Measurement of angiogenic factors, or their expression in certain pre-malignant conditions, may provide further information as to which disease may become invasive, and could possibly be used as a follow-up tool. The current treatment of pre-malignant conditions is usually surgical, although the early results of anti-angiogenesis therapy in animal models show encouraging results. Prevention is always better than cure, and the identification of pre-malignant lesions with intervention to prevent malignant transformation may soon become a realistic goal.
