Genetic alterations in primary breast cancer

Breast cancers with EGFR and HER2 co-amplification favor distant metastasis and poor clinical outcome

ErbB signaling serves essential roles in invasive ductal carcinoma (IDC). The aim of the present study was to assess gene amplification in ErbB family members in IDC with clinical implications. Quantitative polymerase chain reaction and fluorescence in situ hybridization were performed on formalin-fixed paraffin-embedded tumor samples for gene amplification detection. The clinical and histopathological characteristics, as well as the prognostic significance, were analyzed. Among the 119 IDC patients evaluated, epidermal growth factor receptor [EGFR; also known as human epidermal growth factor receptor (HER)1], HER2, HER3 and HER4 gene amplification was observed in 30 (25.2%), 44 (36.9%), 0 (0.0%) and 1 (0.8%) patients, respectively. EGFR amplification was associated with estrogen receptor status (P=0.028) and higher possibilities of recurrence (P=0.015) and distant metastasis (following initial surgery) (P=0.011). In survival analysis, EGFR amplification was also associated with disease-free survival (DFS) (P=0.001) and overall survival (OS) (P=0.003). HER2 amplification was associated with larger tumor size (P=0.006), later clinical stage (P=0.003) and distant metastasis (following initial surgery) (P=0.006). In survival analysis, HER2 amplification was also associated with DFS (P=0.011). Notably, the present study identified a group of patients in whom EGFR and HER2 were co-amplified. This group of patients appeared to have a higher possibility of metastasis (when diagnosed) (P=0.014) and distant metastasis (following initial surgery) (P<0.001). In survival analysis, these patients were noticed to be associated with DFS (P<0.001) and OS (P=0.002). With respect to treatment regimen, this was also true for the DFS association with chemotherapy (P<0.001), radiotherapy (P<0.001) and hormonal therapy (P=0.001). The present results suggest that EGFR and HER2 amplification favor distant metastasis following initial surgery and are significantly associated with poor clinical outcome in breast cancer patients.

Radish (Raphanus sativus L. leaf) ethanol extract inhibits protein and mRNA expression of ErbB(2) and ErbB(3) in MDA-MB-231 human breast cancer cells

In this study, we investigated the effects of the ethanol extract of aerial parts of Raphanus sativus L. (ERL) on breast cancer cell proliferation and gene expression associated with cell proliferation and apoptosis in MDA-MB-231 human breast cancer cells. The MDA-MB-231 cells were cultured in the presence or absence of various concentrations (100, 200, or 300 µg/mL) of ERL. ERL significantly decreased cell proliferation after 48 h of incubation (P < 0.05). The protein and mRNA expression of ErbB(2) were decreased significantly in a dose-dependent manner (P < 0.05). The protein expression of ErbB(3) was decreased significantly at an ERL concentration of 300 µg/mL (P < 0.05), and mRNA expression of ErbB(3) was decreased significantly in a dose-dependent manner (P < 0.05). The protein expression of Akt was decreased significantly at the ERL concentration of 200 µg/mL (P < 0.05), and the protein expression of pAkt was decreased significantly in a dose-dependent manner (P < 0.05). The mRNA expression of Akt was decreased significantly at the ERL concentration of 200 µg/mL ERL (P < 0.05). The protein and mRNA expression of Bax were increased significantly at ERL concentrations of 200 µg/mL or higher (P < 0.05). The protein expression of Bcl(2) was increased significantly at ERL concentrations of 100 µg/mL or higher (P < 0.05), and mRNA expression of Bcl(2) was increased significantly at an ERL concentration of 300 µg/mL (P < 0.05). In conclusion, we suggest that Raphanus sativus, L. inhibits cell proliferation via the ErbB-Akt pathway in MDA-MB-231 cells.

An alternative and reliable real-time quantitative PCR method to determine HER2/neu amplification in breast cancer

The overexpression of HER-2/neu is an independent prognostic factor of clinical outcome of breast cancer, therefore determination of HER-2/neu status is now an integral part of the clinicopathologic workup. The ways of measuring the copy number of the HER-2/neu gene in tumor cells comprise in situ hybridization techniques and real-time polymerase chain reaction (PCR). Quantitative real-time PCR is a relatively new technique for assessing HER-2/neu gene amplification with high sensitivity. However, the HER-2/neu Quantification Kit developed by Roche designed for a LightCycler 1.5 platform had been withdrawn from the commercial market; therefore, we were encouraged to design an alternative LightCycler-based method that offers the desired level of reliability. One hundred breast cancer cases with known HER-2/neu status have been examined with the original Roche developed HER-2/neu Quantification kit and the custom real-time PCR assay. The newly developed, custom PCR showed sensitivity of 91.43%, specificity of 90.63%, and accuracy of 90.91% taking fluorescence in situ hybridization results as the end point. We have described a novel real-time PCR technique for the relative quantification of the HER2/neu gene on a LightCycler 1.5 platform. We have determined that our method is eligible and ideal for the supplement of regular fluorescence in situ hybridization reactions, concerning its high sensitivity and reliability.

Molecular markers (c-erbB-2, p53) in breast cancer

The aim of our study was to evaluate the correlation between clinical characteristics, histopatologic features and c-erbB-2 as well as p53 expression in cancer tissues. Breast cancer tissue was obtained from 184 female subjects with primary breast cancer. According to hormonal status patients were divided into two groups - 64 belonged to the premenopausal group and 120 to postmenopausal group. Each patient underwent mammectomy and axillary lymphadenectomy. c-erbB-2 protooncogene was detected in 54% cases, and was correlated with infiltrating type of cancer growth, as well as larger tumor size. The presence of p53 antioncogene was observed only in 33% of cases, mainly in infiltrating duct carcinomas. The incidence of c-erbB-2 and p53 positive cases was higher among subjects, whose ultrasound and mammography revealed malignancy. There was no correlation found between of c-erbB-2 expression and axillary lymph nodes involvement It seems probable, that c-erbB-2 and p53 status of cancer tissue may prove to be useful in assessment of the level of biological aggressiveness in breast carcinomas and hence can be used as a prognostic factor.

Real-time PCR complements immunohistochemistry in the determination of HER-2/neu status in breast cancer

Background

The clinical benefit of determining the status of HER-2/neu amplification in breast cancer patients is well accepted. Although immunohistochemistry (IHC) is the most frequently used method to assess the over-expression of HER-2 protein, fluorescent in-situ hybridization (FISH) is recognized as the "gold standard" for the determining of HER-2/neu status. The greatest discordance between the two methods occurs among breast tumors that receive an indeterminate IHC score of 2+. More recently, a real-time polymerase chain reaction (PCR) assay using the LightCycler^® has been developed for quantifying HER-2/neu gene amplification. In this study, we evaluated the sensitivity and specificity of a commercially available LightCycler assay as it compares to FISH. To determine whether this assay provides an accurate alternative for the determination of HER-2/neu status, we focused primarily on tumors that were deemed indeterminate or borderline status by IHC.

Methods

Thirty-nine breast tumors receiving an IHC score of 2+ were evaluated by both FISH and LightCycler^® technologies in order to determine whether quantitative real-time PCR provides an accurate alternative for the determination of HER-2/neu status.

Results

We found a high concordance (92%) between FISH and real-time PCR results. We also observed that 10% of these tumors were positive for gene amplification by both FISH and real-time PCR.

Conclusion

The data show that the results obtained for the gene amplification of HER-2/neu by real-time PCR on the LightCycler^® instrument is comparable to results obtained by FISH. These results therefore suggest that real-time PCR analysis, using the LightCycler^®, is a viable alternative to FISH for reassessing breast tumors which receive an IHC score of 2+, and that a combined IHC and real-time PCR approach for the determination of HER-2 status in breast cancer patients may be an effective and efficient strategy.

Correlation of breast cancer risk factors with HER-2/neu protein overexpression according to menopausal and estrogen receptor status

Background

Several researchers have claimed that classification of tumours on the basis of HER-2/neu overexpression or amplification may define a subset of breast cancer in which the net effect of a risk factor could be rather more obvious and its impact on breast cancer development more clear. We decided to investigate, in a group of patients from a geographical area with a low incidence of breast cancer, whether HER-2/neu positive tumours are correlated with established or suspected risk factors for breast cancer and thus to identify distinct subgroups of high risk women.

Methods

This study analysed data from patients who attended the Breast Unit at the University Hospital of Heraklion, Crete, Greece between 1996 and 2002. 384 women with primary invasive breast cancer were compared with 566 screened women who were referred to the Unit and had not developed breast neoplasm by the time the data were analysed. Risk factor data were obtained from each subject by personal interviews using a structured questionnaire. The detection and scoring of the HER-2/neu protein, estrogen and progesterone receptor expression were performed using immunochemistry. Odds ratios and 95% confidence intervals were determined by chi-square test and logistic regression analysis. Case-case odds ratios were calculated in order to measure the risk heterogeneity between HER-2/neu+ and HER-2/neu-tumours. Separate analyses were performed for premenopausal and postmenopausal women and according to estrogen receptor status.

Results

In multivariate analysis without HER-2/neu stratification, an increased breast cancer risk was associated with only four of the factors examined: use of oral contraceptives (OR = 4.40, 95%C.I: 1.46–13.28), use of HRT (OR = 7.34, 95%C.I: 2.03–26.53), an age at first full pregnancy more than 23 years (OR = 1.91, 95%C.I: 1.29–2.83) and body mass index more than 29 kg/m² (OR = 3.13, 95%C.I: 2.02–4.84). Additionally, a history of abortion or miscarriage (OR = 0.56, 95%C.I: 0.38–0.82) was correlated with a decreased risk of breast cancer. In the case to case comparison only BMI >29 kg/m² revealed a relative connection that was stronger with positive than with negative HER-2/neu tumours (ratio of OR's = 2.23, 95%C.I: 1.20–4.15, p = 0.011). This may indicate evidence of heterogeneity of a rather significant degree for this factor. In the ER negative group an age at first full pregnancy >23 years and a BMI >29 kg/m² were associated with an increased risk in both HER-2/neu groups, but the association was significantly stronger for the latter factor in the positive HER-2/neu tumours (ratio of OR's = 2.46, 95%CI: 0.97–6.21).

Conclusions

Our study did not confirm that the established or putative hormonal breast cancer risk factors differ regarding their relations with HER-2/neu+ versus HER-2/neu-breast tumours, with the exception of increased BMI. Further innovative studies with larger sample sizes are needed to examine how the status of these potentially modifiable breast cancer risk factors interacts with biological markers such as HER-2/neu oncoprotein.

Identification of novel breast tumor-specific mutation(s) in the q11.2 region of chromosome 17 by RAPD/AP-PCR fingerprinting

Analysis of genetic instability in breast cancer tissues compared to uninvolved breast tissues from the same individuals by RAPD (random amplified polymorphic DNA)/AP-PCR (arbitrarily primed PCR) fingerprinting using 30 arbitrary primers revealed 190 amplified DNA fragments. Presumably, each of these represents a gene locus in a different region of the genome of breast cancer tissues. Among these amplified DNA fragments, 65 (34.2%) exhibited presence and absence or reductions and enhancements in the intensity in breast cancer tissues compared to uninvolved breast tissues from the same individuals, and 11 amplified DNA fragments (5.7%) represented polymorphisms in the uninvolved human breast tissues. Reductions and enhancements in the intensity of some of the amplified fragments were observed indicating allelic gains or losses in the breast tumor genome compared to the matched uninvolved tissue genome. The presence or absence of some of the amplified DNA fragments were observed in this study indicating homozygous deletions or insertions in the breast tumor DNA compared to the matched uninvolved tissue DNA. Notably, an insertion of a 1270 bp amplified fragment was observed in 81% (17 of 21) of the tumor samples using the primer, OPC04. This amplified fragment resolved into two, 1200 and 1300 bp, single-stranded amplified fragments on the denaturing sequencing gel. This separation into single-stranded fragments suggests that the amplified fragment contains a conformation that is semistable. The 1270 bp amplified fragment localizes to the q11.2 region of chromosome 17. Sequence analysis of this fragment showed a significant DNA base sequence similarity (93%) with one of the breast tumor-specific human EST. The similarity with EST sequences and RT-PCR analysis showed that a part of this amplified fragment is from the coding region of the genome. Any one of the events observed in this study could play an important role in the development of breast cancer or could occur during the clonal expansion of the genetically unstable breast cells.

Disabled-2 exerts its tumor suppressor activity by uncoupling c-Fos expression and MAP kinase activation

Disabled-2 (Dab2) is a putative tumor suppressor in breast and ovarian cancers. Its expression is lost in a majority of tumors, and homozygous deletions have been identified in a small percentage of tumors. Dab2 expression is absent or very low in the majority of breast and ovarian cancer cell lines, including MCF-7 and SK-Br-3 breast cancer cells. Transfection and expression of Dab2 in MCF-7 and SK-Br-3 cells suppress tumorigenicity. The cells reach a much lower saturation density and have reduced ability to form colonies on agar plates. In examining the signal transduction pathway of Dab2-transfected cells, we found that serum-stimulated c-Fos expression was greatly suppressed; however, the effects of Dab2 on MAPK family kinases were not as consistent. In MCF-7 and SK-Br-3 cells, although c-Fos expression was suppressed, the Erk1/2, JNK, and p38(MAPK) activities were unchanged or even increased. Serum-stimulated c-Fos expression is dependent on MAPK/Erk activity because the MEK inhibitor PD98059 suppresses Erk activity and c-Fos expression. Therefore, Dab2 appears to uncouple MAPK activation and c-fos transcription. Thus, we conclude that Dab2 re-expression suppresses tumorigenicity by reducing c-Fos expression at a site downstream of the activation of MAPK family kinases. Because Dab2 is frequently lost in cancer, the uncoupling of MAPK activation and c-Fos expression may be a favored target for inactivation in tumorigenicity.

Amplification of chromosome band 11q13 and a role for cyclin D1 in human breast cancer

In this paper we describe how research on the mouse mammary tumor virus model of breast cancer resulted in the identification of an amplified region of DNA on human chromosome 11 band q13. This amplification occurs in approximately 15% of primary breast cancers. Several candidate oncogenes map within the amplicon but by analysing expression of these genes a strong case can be made for a role for cyclin D1 in tumorigenesis. Immunohistochemical staining indicates that cyclin D1 is expressed at elevated levels in around 40% of breast cancers, including those with the 11q13 amplification. The potential function of cyclin D1 as a regulator of early cell division cycle events would be consistent with a role in neoplasia.

Role of the gene on trisomic and pentasomic chromosome 13 in murine mammary tumorigenesis

To study a possible role(s) played by the trisomy and pentasomy of chromosome 13 in murine mammary tumors, we examined, in eight cloned established cell lines derived from a single BALB/c mammary tumor induced by MTV, a correlation between the presence of trisomy or pentasomy 13 and transformation parameters and in vivo tumorigenicity in syngeneic mice. We found that cell lines with a higher incidence of trisomy or pentasomy 13 in cells of diploid and tetraploid chromosome numbers, respectively, grew to a much higher cell density in flasks than did those with low incidence, and they formed tumors in syngeneic BALB/c mice, whereas those with a low incidence of trisomy or pentasomy 13 were poorly tumorigenic. The presence in the tumorigenic cells of trisomy or pentasomy 13 was not correlated with their growth in soft agar. Furthermore, other chromosomes manifested a wide range of copy numbers in the presence of trisomy or pentasomy 13, indicating that no chromosomes counteracted chromosome 13 to prevent the tumorigenicity. In light of the tumorigenic growth of the cells that maintain gene dosage of chromosome 13 at different ploidy levels, the possibility of the yeast G1 cyclin-like roles played by the gene(s) residing on chromosome 13 in murine mammary tumorigenesis is discussed.

Somatostatin receptor-positive primary breast tumors: genetic, patient and tumor characteristics

In a series of 87 primary breast tumors, somatostatin receptor (SSR) expression was detected by in vitro autoradiography in 58 tumors. In 41 tumors the SSR expression was homogeneous and in 17 it was heterogeneous. Although the tumors were not selected by the investigators upon entry in the study, examination of the tumor and patient characteristics showed that a pre-selection had taken place for small tumors. Eighty percent of the tumors were classified as stage pT1 or pT2 tumors. This small tumor size and the large size of the tumor sections used for autoradiography can explain the high incidence of somatostatin expression in our series. Forty-three of these tumors, 30 SSR-positive and 13 SSR-negative, were tested for morphological and (immuno)histochemical markers of neuroendocrine differentiation. Three SSR-positive tumors were also positive for 2 or more other markers of neuroendocrine differentiation, suggesting that neuroendocrine breast tumors and SSR-positive breast tumors are overlapping, but independent, subgroups of tumors. To test whether specific genetic alterations are associated with SSR-positive or SSR-negative breast tumors, we examined in a selected series of 47 SSR-positive and 32 SSR-negative breast tumors a number of known genetic markers by Southern blotting. Deletions or rearrangements of the retinoblastoma (RB) tumor-suppressor gene were observed in 5 SSR-positive and 5 SSR-negative tumors. In 4 SSR-positive and also in 4 SSR-negative tumors an amplification of the neu oncogene was observed. Amplifications of the int-2 oncogene were found in 2 SSR-positive and 1 SSR-negative breast tumor. In one SSR-positive tumor an amplification of the c-myc oncogene was observed and in another SSR-positive tumor a rearrangement of the L-myc oncogene was found.

int-2 amplification in breast cancer: association with decreased survival and relationship to amplification of c-erbB-2 and c-myc

Amplification of the int-2 oncogene was measured in a series of breast tumours and related to amplification of the c-myc and c-erbB-2 oncogenes, histopathological features and relapse-free and overall survival. int-2 was amplified in 11%, c-myc in 20% and c-erbB-2 in 27% of the tumours assessed. int-2 amplification was associated with large tumour size (p < 0.05) and reduced relapse-free (p < 0.05) and overall (p < 0.0005) survival. c-myc amplification was associated with poor tumour differentiation (p < 0.05) but had no association with prognosis. c-erbB-2 amplification was associated with low levels of expression of oestrogen receptor mRNA (p < 0.05), poor tumour differentiation (p < 0.05) and shortened relapse-free (p < 0.0001) and overall survival (p < 0.0001). This is the first report of an association between amplification of the int-2 oncogene in breast tumours and a significantly increased risk of death from breast cancer, and suggests that int-2 may be useful for identifying breast-cancer patients having a poor prognosis.

Expression of the c-erbB-2 proto-oncogene product and nuclear DNA content in benign and malignant human breast parenchyma

The expression of the c-erbB-2 proto-oncogene product was investigated immunohistochemically in 474 formalin-fixed and paraffin-embedded human breast tissue samples. The series included 32 benign and 26 hyperplastic lesions, 32 carcinomas in situ and 384 invasive breast carcinomas, 107 of which were less than 1 cm in diameter. Cytometric DNA assessments were performed on histopathologically or cytodiagnostically identified cell nuclei, using image analysis. C-erbB-2 immunoreactivity was not seen in normal parenchyma or in benign and hyperplastic lesions. Mammary carcinomas in situ were more frequently immunoreactive (59%) than invasive neoplasms (23%). Invasive tumours more than 1 cm in diameter immunoreacted more often (26%) than small invasive carcinomas (16%). C-erbB-2 expression in regional lymph node metastases was the same as in the corresponding primary tumours. Significant differences were observed between the c-erbB-2 expression in DNA diploid and aneuploid lesions; for carcinomas in situ the figures were 40% and 72%, respectively. Invasive carcinomas of DNA diploid type rarely showed c-erb-B-2 expression, irrespective of tumour size and nodal status (7-11%). DNA aneuploid tumours were more frequently immunoreactive with increasing levels during progression (32-41%). Our data indicate that genetically stable invasive mammary tumours seem rarely to express the c-erbB-2 protein, even during progression, whereas genetically unstable invasive neoplasms frequently show c-erbB-2 immunoreactivity which increases during tumour progression.

Somatic mutations and human breast cancer. A status report

A systematic study of primary human breast tumor DNA demonstrated that three proto-oncogenes or regions of the genome (c-myc, int-2, and c-erbB2) are frequently amplified and that there is loss of heterozygosity (LOH) on chromosomes 1p(37%), 1q(20%), 3p(30%), 7(41%), 11p(20%), 13q(30%), 17p(49%), 17q(29%), and 18q(34%). Specific subsets of tumors can be defined based on the particular collection of mutations they contain. For instance, LOH on chromosomes 11p, 17p, and 18q frequently occurs in the same tumor. A search for putative tumor suppressor genes within the regions of the genome affected by LOH has been started. In a comprehensive molecular analysis of the p53 gene on chromosome 17p, 46% of the tumors contained a point mutation in the p53 gene.

Tumor suppressor genes: a new era for molecular genetic studies of cancer

Previous emphasis in cancer research has been placed on genes in which activating mutations are found in experimental systems and sometimes in human tumors, and many of these genes are the cellular homologs of retroviral oncogenes. Studies of genes whose functions are necessary for maintenance of the normal cellular state, but for which loss-of-function mutations lead to tumor development, are limited. The latter genes have been variously termed 'tumor suppressor genes', 'recessive oncogenes', and 'anti-oncogenes', and each term defines a specific aspect of their properties and may not always be applicable. The retinoblastoma (RB) gene is the first such gene to be identified, and was isolated based on its chromosome localization and on the recessive nature of the tumor phenotype. That is, both wild type RB alleles must be inactivated in a single cell for neoplastic transformation to occur, and deletions at the chromosomal locus now known to contain RB are often found in retinoblastoma cells. Candidate genes for Wilms' tumor and neurofibromatosis type I have also been identified recently, and loss of function of these genes seems to be indicated for these diseases. Allelic loss of chromosome 17p13 is frequently observed in many tumor types. The p53 gene was mapped to this chromosomal region and has been shown to be a tumor suppressor gene, and germ-line mutations of p53 recently were found to be correlated with Li-Fraumeni syndrome, a syndrome characterized by multiple neoplasms. Rapid progress in studies of tumor suppressor genes points to diverse mechanisms for their functioning in the negative regulation of cell growth. A scenario depicting cell growth control by positive and negative regulators, based on new and emerging findings, is the main focus of this review.

Medical management of early-stage breast cancer

With improved screening and education, a greater proportion of breast cancer is detected at an early stage. Although the prognosis for many of these patients is excellent following definitive local therapy alone, some subsets of node-negative patients have a 30% chance of eventually developing metastatic disease that will be incurable with current therapy. Thus, an increasing proportion of early-stage patients are being offered some form of adjuvant therapy, with the expectation of improved relapse-free survival, and possibly improved overall survival. Efforts have been made to base the selection of patients for adjuvant therapy on specific prognostic factors. Meanwhile, the scope and complexity of putative prognostic factors continues to widen, and now includes such items as the presence of occult microscopic metastases, DNA ploidy and proliferative fraction, cytogenetic abnormalities, oncogene expression, growth factor receptors, and expression of hormonally regulated proteins. In addition, there is now a considerable range of options with regard to the composition, dose intensity, and sequence of multimodality therapy. Data regarding the classification, significance, and interpretation of prognostic factors is reviewed together with the development, current status, and recommendations regarding adjuvant therapy for patients with early-stage breast cancer. For 1991, the National Cancer Institute (NCI) has estimated that 175,000 new cases of breast cancer will be diagnosed in American women. It is also estimated that 44,500 women will die of breast cancer. Unfortunately, the age-adjusted death rate from breast cancer has shown no overall change from 1930 through 1987. However, effective screening techniques continue to identify an increasing percentage of early-stage tumors, which should exceed 50% of all new tumors in 1991. Ultimately, our understanding of environmental and genetic risk factors may identify new ways to reduce the impact of this disease. In the interim, development and application of effective systemic adjuvant chemotherapy and hormonal therapy has become increasingly important. There is no question that a greater proportion of patients with less extensive disease are now being offered some form of adjuvant therapy. Meanwhile, selection of patients for adjuvant therapy, and choice among specific adjuvant regimens, has remained controversial. Analysis of multiple prognostic factors is performed not only in the context of cooperative investigational trials, but more often in the offices of individual physicians caring for individual patients. Tumor biopsies can now be routinely sent to specialized laboratories for performance of complex assays with potential prognostic information, although interpretation of these results with reference to a specific patient is often uncertain.(ABSTRACT TRUNCATED AT 400 WORDS)

Association of INT2/HST1 coamplification in primary breast cancer with hormone-dependent phenotype and poor prognosis

The human proto-oncogene INT2 (homologous to the mouse INT2 gene, implicated in proviral induced mammary carcinoma) has been mapped to chromosome 11q13 and found to share band localisation with, among others, the HST1 proto-oncogene. Both genes are members of the fibroblast growth factor family. In the present study, coamplification (2-15 copies) of the INT2/HST1 genes was found in 27 (9%) of 311 invasive human breast carcinomas using slot blot and Southern blot analyses. Amplification was not correlated to tumour size, axillary lymph node status or stage of disease, neither to patient age nor menopausal status. However, 26 (96%) of the 27 amplified tumours were, often strongly, Oestrogen receptor positive compared to 65% of the unamplified cases (P = 0.001). These findings are in sharp contrast to the strong correlations of HER-2/neu proto-oncogene amplification with advanced stage and steroid receptor negativity, previously observed in the same series of tumours. Patients with INT2/HST1 amplified breast cancer had a significantly shorter disease-free survival compared to those with unamplified genes (P = 0.015, median follow up 45 months). This correlation was confined to node-negative patients and persisted in multivariate analysis. No significant correlation to survival from breast cancer was found. It is concluded that amplification of the 11q13 region in breast cancer occurs in a particular subset of aggressive tumours, quite different from that identified by HER-2/neu amplification. It still remains to be shown that the selection for amplified genes at 11q13 is due to the activity of INT2, HST1 or yet another, still unidentified, neighbouring gene. However, the results are potentially of clinical value in separating a group of node-negative breast cancer for more intense treatment.

Genetic changes in somatostatin receptor positive breast tumors

Forty-nine primary breast tumors were analyzed for the expression of the somatostatin receptor (SSR) and genetic changes in the RB tumor suppressor gene. Twenty-four tumor samples were shown to contain receptors for somatostatin and in eight of these SSR-positive tumors we observed a mutation in the RB gene. However, since also in the group of SSR-negative tumors in eight of the 25 cases an alteration of the RB gene was observed, loss of this tumor suppressor gene is not specific for the SSR-positive subgroup of breast tumors. A similar, equal distribution between SSR-positive and SSR-negative breast tumors was observed for the six tumor samples which showed amplification of the neu proto-oncogene.

Epidermal growth factor receptors and prognosis in primary breast cancer

A retrospective study was performed on 109 human breast tumors stored in liquid nitrogen in order to assess the prognostic value of epidermal growth factor receptor (EGF-R) (median patient follow-up 5 years). A significant inverse relationship was observed between EGF-R and both estrogen (ER) and progesterone receptors (PR). Univariate analysis showed a trend towards a shorter metastasis-free survival both in the overall population and in node-negative patients with EGF-R positive tumors. Multivariate analysis of the overall population showed that lymph-node involvement and PR status were the only significant variables in predicting metastasis-free survival. However, in patients receiving no adjuvant treatment (hormone therapy or chemotherapy). EGF was the only significant variable in the multivariate Cox analysis. No c-erbB-1 amplification was detected in these tumors.

Oncogene amplification correlates with dense lymphocyte infiltration in human breast cancers: a role for hematopoietic growth factor release by tumor cells?

One hundred six primary breast cancer samples were analysed for c-erbB2, int-2, and c-myc gene amplification. Surgically confirmed nodal involvement was observed in 42%. Level of gene amplification was studied by Southern and/or slot blot techniques. Amplified c-erbB2 gene sequences were present in 21.5% of all samples. Int-2 was amplified in 13.1% and c-myc was amplified in 10.3%. In a non-parametric test (Kruskal-Wallis) a strong negative association was found between high levels of c-erbB2 amplification and absence of estrogen receptor (ER) (P = .0009) or progesterone receptor (PR) (P = .011) expression. No correlations were found between all or high levels of amplification of each oncogene separately or combined with T, N, grade, multifocality of tumor, or associated carcinoma in situ. There was a trend approaching statistical significance for patients with c-erbB2 amplifications to have positive lymph nodes at surgery (P = 0.09). A somewhat surprising finding however was a very strong association between oncogene amplification and dense lymphocyte infiltration of the tumor (P = .05). This correlation is even stronger when only high levels of amplification are considered, either for each oncogene separately (P = .0048) or in combination (P = .0007). We propose that malignant cell cytokine production may help explain this observation.

Loss of heterozygosity on chromosomes 17 and 18 in breast carcinoma: two additional regions identified

The loss of heterozygosity (LOH) at specific regions of the human genome in tumor DNA is recognized as evidence for a tumor-suppressor gene located within the corresponding region of the homologous chromosome. Restriction fragment length polymorphism analysis of a panel of primary human breast tumor DNAs has led to the identification of two additional regions on chromosomes 17q and 18q that frequently are affected by LOH. Deletions of each of these regions have a significant correlation with clinical parameters that are associated with aggressive breast carcinomas. Previous restriction fragment length polymorphism analysis of this panel of tumors has uncovered several other frequently occurring mutations. LOH on chromosome 18q frequently occurs in tumors with concomitant LOH of loci on chromosomes 17p and 11p. Similarly, tumors having LOH on 17q also have LOH on chromosomes 1p and 3p. This suggests that certain combinations of mutations may collaborate in the development and malignant progression of breast carcinomas.

Prognostic indicators in invasive breast cancer

Tumor size and axillary lymph node involvement are the primary determinants of clinical course for most patients. Receptors for estrogen and progesterone are important additional prognostic factors for disease-free survival, overall survival, survival time after initial disease recurrence, and the likelihood of response to hormonal therapy. Histologic grading has merit as a prognostic factor, although poor reproducibility limits its broad application. Promising data have been emerging from the use of flow cytometry to analyze DNA content and proliferative rate. Patients with aneuploid tumors are more likely to have a shorter survival time than patients with diploid tumors. A high S-phase fraction also identifies a subset of patients at increased risk for early relapse. A combined index of ploidy and S-phase may be a more useful guide; together, diploidy and low S-phase identify a subgroup of node-negative patients at very low risk for disease recurrence. A number of oncogenes have been identified in breast cancer; amplification of the HER-2/neu gene or overexpression of the gene product may be an important prognostic indicator for node-positive patients.

Normal diploid human and rodent cells lack a detectable frequency of gene amplification

Gene amplification is frequently observed in tumors and transformed cell lines. This phenomenon is known to contribute to the generation of drug-resistant tumor cells and quantitation of the event is believed to have prognostic value in several types of neoplasias. To date, most studies of gene amplification have used immortalized cell lines and biopsied tumor samples. In this study I examine the amplification potentials of primary diploid cells, both human and rodent, and quantitatively compare them to the amplification potentials of their transformed counterparts. I have used a strictly defined protocol (i.e., selection at a stringency of 9 X LD50) to measure amplification potential at two loci, the gene for the multifunctional protein containing activities for carbamoyl phosphate synthase, aspartate transcarbamylase, and dihydroorotase (CAD) and the gene for dihydrofolate reductase (DHFR). I find that the frequency of amplification in transformed cells is at least four orders of magnitude greater than that in normal cells. Out of 29 cell populations studied, the 7 diploid normal cell populations exhibited no detectable amplification frequency (limit of detection at 10(-8) whereas the 22 transformed cell lines demonstrated amplification frequencies between 10(-3) and 10(-7). These results demonstrate that a dramatic difference exists between primary diploid cell populations and immortalized cell populations in their ability to amplify genomic sequences and suggests a significant difference in genetic stability between these two cell types.