Simultaneous Quantitative Detection of Relevant Biomarkers in Breast Cancer by Quantitative Real-Time PCR

The assessment of ERα, PgR and HER2 status is routinely performed today to determine the endocrine responsiveness of breast cancer samples. Such determination is usually accomplished by means of immunohistochemistry and in case of HER2 amplification by means of fluorescent in situ hybridization (FISH). The analysis of these markers can be improved by simultaneous measurements using quantitative real-time PCR (Qrt-PCR). In this study we compared Qrt-PCR results for the assessment of mRNA levels of ERα, PgR, and the members of the human epidermal growth factor receptor family, HER1, HER2, HER3 and HER4. The results were obtained in two independent laboratories using two different methods, SYBR Green I and TaqMan probes, and different primers. By linear regression we demonstrated a good concordance for all six markers. The quantitative mRNA expression levels of ERα, PgR and HER2 also strongly correlated with the respective quantitative protein expression levels prospectively detected by EIA in both laboratories. In addition, HER2 mRNA expression levels correlated well with gene amplification detected by FISH in the same biopsies. Our results indicate that both Qrt-PCR methods were robust and sensitive tools for routine diagnostics and consistent with standard methodologies. The developed simultaneous assessment of several biomarkers is fast and labor effective and allows optimization of the clinical decision-making process in breast cancer tissue and/or core biopsies.

Molecular profiles of prostate cancer versus today’s diagnostic tools

14659

Background: Tumor size, nodal status, the Gleason grading system and serum PSA values are today’s available prognostic tools of localized prostate cancer and the only help for adjuvant therapy. Based on the results of a feasibility study we continued the evaluation of the recently developed prognostic molecular signature. Methods: Of 60 CaP patients, who underwent primary prostatectomy in 2003 to 2005, fresh frozen samples of the tumor were asserved. The RNA extracted from cryocuts was tested. The quantitative RNA expression levels of 90 relevant genes involved in the different tumor hallmarks were simultaneously assessed. Results: Unsupervised agglomerative clustering of the obtained molecular profiles revealed different signatures. Correlations between these groups and the known TNM staging as well as Gleason scores were strongly present. Of interest was that all recurrences observed within this short period of time were found in a single cluster expressing higher levels of proliferation markers. Conclusions: The molecular profile of primary prostate cancer by quantitative RT-PCR is a powerful tool describing the biology of an individual tumor. Gene expression profiling can be precisely quantified and seems to be better reproducible than pathological judgments of the Gleason scores. Moreover, the gene panel is partially based on drug target genes and therefore of predictive value. Finally the method could be applied also in core biopsies.

[Table: see text]

Simultaneous quantitative detection of relevant biomarkers in breast cancer by quantitative real-time PCR

The assessment of ERa, PgR and HER2 status is routinely performed today to determine the endocrine responsiveness of breast cancer samples. Such determination is usually accomplished by means of immunohistochemistry and in case of HER2 amplification by means of fluorescent in situ hybridization (FISH). The analysis of these markers can be improved by simultaneous measurements using quantitative real-time PCR (Qrt-PCR). In this study we compared Qrt-PCR results for the assessment of mRNA levels of ERa, PgR, and the members of the human epidermal growth factor receptor family, HER1, HER2, HER3 and HER4. The results were obtained in two independent laboratories using two different methods, SYBR Green I and TaqMan probes, and different primers. By linear regression we demonstrated a good concordance for all six markers. The quantitative mRNA expression levels of ERa, PgR and HER2 also strongly correlated with the respective quantitative protein expression levels prospectively detected by EIA in both laboratories. In addition, HER2 mRNA expression levels correlated well with gene amplification detected by FISH in the same biopsies. Our results indicate that both Qrt-PCR methods were robust and sensitive tools for routine diagnostics and consistent with standard methodologies. The developed simultaneous assessment of several biomarkers is fast and labor effective and allows optimization of the clinical decision-making process in breast cancer tissue and/or core biopsies.

Different prediction of distant recurrence risk in primary breast cancer patients stratified by ER and ERBB2 status

20120

Background: Molecular profiling recently defined biological characteristics of several long-recognized breast cancer subtypes including ER-positive (luminal subtype), ER-negative/ERBB2-positive (ERBB2 subtype) and ER-negative/ErBB2-negative (basal-like subtype). Each of these particular subtypes has different impact on patient outcome and should be therefore taken in consideration for individual scoring calculations. Methods: The quantitative RNA expression levels of 70 relevant genes were simultaneously determined in fresh frozen samples of 317 primary breast cancer (BC) patients comprehending ER-positive (70%), ER-negative/ERBB2-positive (15%) and ERBB2-negative/ER-negative (15%) and with known follow-up data. Five years distant recurrence scoring systems were calculated by means of Cox-hazard regression models. Results: Two main prognostic scoring systems were developed: one based on genes relative to proliferation representing tumor growth and its velocity, the other based on proteases. A low proliferation score identified 30% of patients at very good prognosis (probability of distant recurrence 12%, CI: 1.5–22%) all belonging to the ER-positive subcategory as compared to cases with higher proliferation (probability of distant recurrence 31%, 32–38%). The probability to develop distant recurrence within 5 years for 30% of ERBB2-positive patients was of only 12% (CI 0–25%) when accompanied by low levels of proteases as compared to the remaining ERBB2-positive patients with a probability of recurrence of 40% (CI 22–54%). Conclusions: ER, ERBB2 and the expression levels of the few identified genes involved in tumor proliferation and invasion can be easily and precisely detected by means of QRT-PCR. This robust method allows fine tuned prognosis and gives predictive information for the treatment of individual breast cancer.

[Table: see text]

The NFkappaB pathway and endocrine-resistant breast cancer

Endocrine therapy with an estrogen receptor (ER)-targeted antiestrogen, such as tamoxifen, or estrogen ablation by aromatase inhibitors is clinically indicated for the management of all forms of ER-positive breast cancer. However, 30-50% of ER-positive breast cancer cases fail to benefit clinically from endocrine therapy alone, and recent molecular evidence suggests that 'crosstalk' pathways originating from activated receptor tyrosine kinases and/or other proliferative and survival signals may be contributing to this endocrine resistance. Molecular identification and validation of candidate ER crosstalking pathways will likely lead to clinically important prognostic markers and targets for the application of novel therapeutics in combination with standard endocrine agents. This review focuses on a critical survival and proliferation pathway involving activation of nuclear factor-kappaB (NFkappaB), a family of ubiquitously expressed transcription factors that for nearly two decades have been known to be critical regulators of mammalian immune and inflammatory responses, and more recently have been associated with chemotherapy resistance. With the demonstration that activation of NFkappaB is absolutely required for normal mammary gland development, NFkappaB involvment in human breast cancers was initially explored and linked to the development of hormone-independent (ER-negative) breast cancer. Newer clinical evidence now implicates NFkappaB activation, particularly DNA-binding by the p50 subunit of NFkappaB, as a potential prognostic marker capable of identifying a high-risk subset of ER-positive, primary breast cancers destined for early relapse despite adjuvant endocrine therapy with tamoxifen. Furthermore, initial preclinical studies suggest that treatment strategies designed to prevent or interrupt activation of NFkappaB in cell-line models of these more aggressive, ER-positive breast cancers can restore their sensitivity to such standard endocrine agents as tamoxifen.

Understanding the age dependency of breast cancer biomarkers

This review and study of nearly 4,000 primary breast cancers evaluates the hypothesis that human aging not only increases breast cancer incidence but also alters breast cancer biology. Clinically validated biomarkers were chosen as surrogate measures of genetic instability and tumor growth, invasiveness and metastatic potential. Our results support the premise that breast cancer clinical behavior and biology are significantly affected by patient age, but call into question key aspects of the current cancer-aging paradigm.

BRCA1/2 mutations in Swiss patients with familial or early-onset breast and ovarian cancer

QUESTIONS UNDER STUDY

Germ-line alterations in BRCA1 and BRCA2 genes account for 30-50% of all forms of familial breast and ovarian cancer syndromes. Specific mutations in specific populations and ethnic groups have been identified in BRCA1 and BRCA2. However, it is not known whether such specific mutations prevail in the Swiss population.

METHODS

We started to screen patients with primary breast and ovarian cancer and a strong family history of both cancers by sequencing the full-length coding regions of BRCA1 and BRCA2.

RESULTS

With the selection criteria used in this study we identified 19 mutations in the first 38 patients screened (50%). These mutations were either defined as deleterious and resulted in a protein truncation (n = 10) or were defined as unclassified variants (n = 9). One novel truncating mutation was found in BRCA2 and two novel unclassified variants were detected in BRCA1. These three mutations are not described in the BIC and HGMD databanks.

CONCLUSIONS

We detected three unknown mutations among 38 patients in a Swiss study of BRCA1/2 mutation patterns. One of these novel mutations is clearly deleterious as it leads to protein truncation at nucleotide 133 of BRCA2.

BRCA1/2 mutations in Swiss patients with familial or early-onset breast and ovarian cancer

QUESTIONS UNDER STUDY

Germ-line alterations in BRCA1 and BRCA2 genes account for 30-50% of all forms of familial breast and ovarian cancer syndromes. Specific mutations in specific populations and ethnic groups have been identified in BRCA1 and BRCA2. However, it is not known whether such specific mutations prevail in the Swiss population.

METHODS

We started to screen patients with primary breast and ovarian cancer and a strong family history of both cancers by sequencing the full-length coding regions of BRCA1 and BRCA2.

RESULTS

With the selection criteria used in this study we identified 19 mutations in the first 38 patients screened (50%). These mutations were either defined as deleterious and resulted in a protein truncation (n = 10) or were defined as unclassified variants (n = 9). One novel truncating mutation was found in BRCA2 and two novel unclassified variants were detected in BRCA1. These three mutations are not described in the BIC and HGMD databanks.

CONCLUSIONS

We detected three unknown mutations among 38 patients in a Swiss study of BRCA1/2 mutation patterns. One of these novel mutations is clearly deleterious as it leads to protein truncation at nucleotide 133 of BRCA2.

Prognostic and predictive significance of ErbB-2 breast tumor levels measured by enzyme immunoassay

PURPOSE

A retrospective analysis to assess the prognostic and predictive clinical value of breast tumor ErbB-2 receptor expression quantified by enzyme immunoassay (EIA), to compare levels measured by EIA with ErbB-2 status determined by immunohistochemistry (IHC), and to correlate receptor content with levels of phosphorylated (Y1248-P) ErbB-2, a measure of functional tyrosine kinase activity.

MATERIALS AND METHODS

EIA quantification of ErbB-2 was performed on membrane extracts from 3,208 well-characterized primary breast cancers. Overall, relapse-free, distant disease-free, and local/regional-free patient survival data were available on 1,123 of these tumors. IHC scoring for ErbB-2 status (HercepTest; DAKO, Glostrup, Denmark) was performed on adjacent sections of 151 cases, and receptor functionality was measured in 230 tumors by an antibody specific for phosphorylated (Y1248-P) ErbB-2.

RESULTS

Unlike nonmalignant breast tissues, breast tumors showed increased ErbB-2 levels in a bimodal distribution, with 12% constituting a distinct set of ErbB-2-overexpressing tumors. The intermodal threshold value for ErbB-2 overexpression distinguished tumors with reduced estrogen and progesterone receptor content, high IHC score for ErbB-2, and significantly increased levels of phosphorylated (Y1248-P) ErbB-2 receptor. By multivariate analysis, EIA-determined ErbB-2 overexpression predicted significantly reduced patient survival that was unaffected by tamoxifen or cyclophosphamide, methotrexate, and fluorouracil adjuvant therapy.

CONCLUSION

Determination of ErbB-2 receptor expression by EIA offers a clinically valuable alternative to semiquantitative IHC assessment of breast tumor ErbB-2 overexpression and affords the opportunity to evaluate ErbB-2 phosphorylation, which may represent an important predictive parameter of receptor functionality.

Potential prognostic value of mitogen-activated protein kinase activity for disease-free survival of primary breast cancer patients

Signaling through pathways involving mitogen-activated protein kinases (MAP kinases) has been implicated in the pathogenesis of cancer. Thus, the activity of MAP kinase is essential in the malignant potential of human breast tumors. p42/44(MAPK) was significantly higher expressed in tumor samples than in matching normal tissues adjacent to the tumor. p42/44(MAPK) protein expression correlated with enhanced MAP kinase activity only in a subset of tumors, indicating that over-expression of MAP kinases does not reflect the activation status of these enzymes. MAP kinase activity was significantly elevated in 131 tissue samples from primary breast tumors when compared to 18 normal tissues adjacent to tumors. A trend for higher MAP kinase activity in primary tumors of node-positive patients was observed when compared with tumors from node-negative patients. Similarly, higher MAP kinase activities were observed in specimens from patients who had a relapse within the follow-up time of 40 months when compared with patients with no relapse. A survival analysis demonstrated that the MAP kinase activity in primary breast tumors is potentially prognostic for relapse-free survival of patients.

A yeast-based bioassay for the determination of functional and non-functional estrogen receptors

The response to endocrine therapy of breast cancer is not entirely predictable from hormone receptor status alone since some point mutated or splicing variants of the estrogen receptor (ER) show altered biological activities. In order to characterize the activities of all forms of ER in a heterogeneous breast tumor, a functional assay in Saccharomyces cerevisiae was developed. Total RNA isolated from breast cancer cells and one breast cancer specimen was reverse transcribed and the ER cDNA was amplified by PCR. The products were then cloned into an expression vector by in vivo homologous recombination in yeast. The yeast strain carries a reporter gene ( ADE2 ) coupled to an estrogen response element. Activation of the reporter by ER yielded white colonies whereas lack of ER activity produced red colonies. This permitted the testing for functionality of individual ER molecules and subsequent analysis by rescuing of the ER expression plasmids and complete DNA sequencing. This simple visual test allows discrimination between wild-type ER, constitutively active ER and inactive ER.

Markers of tumor angiogenesis and proteolysis independently define high- and low-risk subsets of node-negative breast cancer patients

PURPOSE

To compare the prognostic impact of tumor angiogenesis factors (vascular endothelial growth factor [VEGF], angiogenin, and basic fibroblast growth factor [bFGF]), tumor proteolysis factors (urokinase-type plasminogen activator [uPA] and plasminogen activator inhibitor-1 [PAI-1]), and conventional tumor markers (stage, grade, and steroid receptors) in early breast cancer.

PATIENTS AND METHODS

In the primary clinical study, tumor angiogenesis and other factors were detected in frozen biopsies from 305 primary breast tumors. VEGF expression was assessed by chemiluminescence immunosorbent assay (ICMA); angiogenin, bFGF, uPA, and PAI-1 by enzyme-linked immunosorbent assay (ELISA); and steroid receptors (estrogen receptor [ER] and progesterone receptor [PgR]) by enzyme immunoassay (EIA). In the validating clinical study, another set of 190 node-negative primary breast tumor samples were collected at a separate institution.

RESULTS

Univariate analysis of the primary study showed that VEGF levels were positively correlated with recurrence (P < .001). Angiogenin levels were positively correlated with disease relapse (P < .005) for the overall collective group, but not within the node-negative subset. No significant correlations were found between tumor bFGF levels and patient survival. In multivariate regression analysis, the only independent predictors of relapse-free survival (RFS) were VEGF, uPA, and lymph node status. In the validation set, the distribution of VEGF and uPA values were similar to those in the primary study; low expression of both VEGF and uPA identified patients with a < or = 20% likelihood of recurrence within 7 years.

CONCLUSION

Separate primary and validating clinical studies concur that tumor VEGF level is the most important prognostic parameter among several markers of tumor angiogenesis and proteolysis.

Agrin can mediate acetylcholine receptor gene expression in muscle by aggregation of muscle-derived neuregulins

The neural isoforms of agrin can stimulate transcription of the acetylcholine receptor (AChR) epsilon subunit gene in electrically active muscle fibers, as does the motor neuron upon the formation of a neuromuscular junction. It is not clear, however, whether this induction involves neuregulins (NRGs), which stimulate AChR subunit gene transcription in vitro by activating ErbB receptors. In this study, we show that agrin- induced induction of AChR epsilon subunit gene transcription is inhibited in cultured myotubes overexpressing an inactive mutant of the ErbB2 receptor, demonstrating involvement of the NRG/ErbB pathway in agrin- induced AChR expression. Furthermore, salt extracts from the surface of cultured myotubes induce tyrosine phosphorylation of ErbB2 receptors, indicating that muscle cells express biological NRG-like activity on their surface. We further demonstrate by RT-PCR analysis that muscle NRGs have Ig-like domains required for their immobilization at heparan sulfate proteoglycans (HSPGs) of the extracellular matrix. In extrasynaptic regions of innervated muscle fibers in vivo, ectopically expressed neural agrin induces the colocalized accumulation of AChRs, muscle-derived NRGs, and HSPGs. By using overlay and radioligand-binding assays we show that the Ig domain of NRGs bind to the HSPGs agrin and perlecan. These findings show that neural agrin can induce AChR subunit gene transcription by aggregating muscle HSPGs on the muscle fiber surface that then serve as a local sink for focal binding of muscle-derived NRGs to regulate AChR gene expression at the neuromuscular junction.

Increased expression of estrogen-receptor exon-5-deletion variant in relapse tissues of human breast cancer

A substantial percentage (30-70%) of human breast carcinomas that initially respond to endocrine therapy acquire resistance during the treatment. Many patients with tumor progression despite treatment with anti-estrogen tamoxifen show continued expression of estrogen receptors (ER) and/or progesterone receptors (PgR) in the relapse tissue. This indicates that, in these tumors, mechanisms other than loss of ER expression are responsible for treatment failure. We have investigated the occurrence and frequency of the exon-5-deletion variant (d5) of ER in human breast-cancer biopsies and in normal tissues. In all normal and tumor tissues tested, both wild-type (wt) and d5 were detected, indicating that expression of the d5 variant is a naturally occurring polymorphism. However, the primary tumors of patients who relapse within 15 months (n = 13) express higher ratios of d5 than do those of patients with no relapse during the same period (p = 0.4, n = 19), though this difference is statistically not significant. A significant increase in the expression level of d5 was determined in relapse as compared with the respective primary tumor (p = 0.02). These data indicate that increased expression of the ER exon-5-deletion variant in relapse tissues might be due to clonal selection of cells resistant to anti-estrogen treatment.

Expression profile of the putative catalytic subunit of the telomerase gene

Telomerase, a ribonucleoprotein complex, adds hexameric repeats called telomeres to the growing ends of chromosomal DNA. The enzyme telomerase activity is present in a vast majority of tumors but is repressed in most normal tissues. Recently, two groups have reported the molecular cloning of the putative catalytic subunit (hEST2/hTRT) of the telomerase gene. We investigated the expression of this gene in diverse tumor-derived cell lines and tumors as well as in various normal tissues. The expression of hEST2/hTRT was detectable in tumor-derived cell lines, primary breast tumors, pancreatic tumors, and kidney tumors. Furthermore, the expression of hEST2/hTRT was down-regulated in response to a differentiation inducer. However, several normal tissues also expressed varying levels of hEST2/hTRT. Early passage cultures of endothelial fibroblasts and some epithelial cells also expressed the telomerase gene, albeit at low levels. In contrast, the expression of TLP1/TP1, the human homologue of Tetrahymena p80 telomerase subunit, was similar in all of these samples. Our results indicate that the differences in expression of hEST2/hTRT in tumor versus normal cells are relative and are not absolute.

Tumor-necrosis factor-alpha modulates mitogen-activated protein kinase activity of epidermal-growth-factor-stimulated MCF-7 breast cancer cells

Tumor-necrosis factor(TNF)-alpha inhibited in a dose-dependent fashion the proliferation of epidermal-growth-factor(EGF)-stimulated MCF-7 breast cancer cells with an IC50 of 0.25 nM. A comparable TNF-alpha-mediated inhibition of p42/44 mitogen-activated protein (MAP) kinase activity was observed in 10 nM EGF-stimulated cells. The MAP kinase activity dropped 50% within 3 min of TNF-alpha (1 nM) addition to EGF-stimulated MCF-7 cells. EGF and TNF-alpha, when added independently, led to a transient stimulation of MAP kinase activity with maximal activations within 6-8 min and 1-2 min, respectively. These observations suggest that MAP kinase activity in EGF-stimulated MCF-7 cells is modulated by the growth-inhibitory receptor pathways of TNF-alpha. Phosphorylation measurements on western blots determined the involvement of several individual MAP kinases, namely p42/44 MAP kinases, p38 MAP kinase and c-Jun N2-terminal kinase 1 (JNK1), in EGF and TNF-alpha-induced signalling. Phosphorylation of p42 and p38 MAP kinases only was observed after treatment with either TNF-alpha or EGF. A combination of both ligands inhibited p42 and p38 MAP kinase phosphorylation in MCF-7 cells. In contrast, no JNK1 phosphorylation was detected in these cells. Simultaneous addition of okadaic acid, a potent inhibitor of phosphatases 1 and 2A, blocked the decay of EGF-stimulated MAP kinase activity over 40 min. TNF-alpha added to EGF-stimulated and okadaic-acid-treated cells increased the MAP kinase activity twofold within 1 min. Similarly, okadaic acid treatment partly reverted the TNF-alpha-inhibited growth of MCF-7 cells. These experiments suggest that phosphatases are involved in the rapid shut-down by TNF-alpha of p42 MAP kinase activity.

Selective modulation of protein kinase A and protein kinase C activities in epidermal growth factor (EGF)-stimulated MCF-7 breast cancer cells

In human MCF-7 breast cancer cells, both protein kinase A (PKA) and different members of the protein kinase C (PKC) family are stimulated upon binding of epidermal growth factor (EGF) to cell surface receptors. Selective stimulation of calcium-dependent PKCs with 10(-6) to 10(-9) M Thymeleatoxin significantly increased the proliferation rate of MCF-7 cells over 5 days in culture. This stimulation was blocked by the PKC antagonist Chelerythrine. In contrast, selective activation of PKA by addition of 1 mM dibutyryl cyclic AMP (dBcAMP) did not affect the proliferation rate of MCF-7 cells. Similarly, activation of the adenylate cyclase by 1 microM Forskolin and inhibition of PKA by the cyclic AMP analogue Rp-cAMPS did not modulate the proliferation rate of these cells. Activation of PKC stimulated the expression of the immediate early gene c-fos but c-myc expression was not significantly enhanced. On the other hand, PKA activation increased both c-myc and c-fos expression in MCF-7 cells. These results suggest that PKA activation and c-myc expression are not obligatory for proliferation of MCF-7 cells.

[Molecular factors determine primary and secondary therapy of breast carcinoma]

The clinical oncology realizes that the classical approach with systemic adjuvant chemo- and hormonal therapies is not sufficient and will be challenged by cellular and molecular structures which reflect the targets for new therapeutic approaches. These targets are key proteins involved in the signal transduction cascade. In human tumors these proteins have either lost their biological functionality by oncogenic mutations or are constitutively activated. The molecular classification of primary breast cancer was performed by assessing the following factors: estrogen- and progesterone receptors, ERbB-2 mutated p53, uPA, PAI-I, VEGF, DNA-Index and S-Phase. These factors are of prognostic and predictive value.

BRCA1 mutations found in archived early onset breast tumours

Inherited mutations in the BRCA1 gene are thought to account for approximately 5% of breast cancers in women under the age of 45 years. In order to determine whether mutations could be found at the expected frequency, 60% of the protein coding region of BRCA1 was screened in 75 archived early-onset breast tumours, taken from women under 45 years of age. Two of the 75 tumours (2.7%) had detectable mutations, in close agreement to that predicted. Since BRCA1 mutations found in breast tumours are invariably germline, two immediate consequences are apparent. Firstly, family members of affected patients are likely to carry mutations as well, and should be considered for BRCA1 screening; and secondly, persons harbouring a germline BRCA1 mutation should be examined frequently and indefinitely for new primary tumours in remaining breast tissue.

Tumour necrosis factor and interferon are selectively cytostatic in vitro for hormone-dependent and hormone-independent human breast cancer cells

Since experimental studies have shown that tumour necrosis factor-alpha (TNF-alpha) has potent anti-tumour activity that can be potentiated with cytokines, we tested the efficacy of TNF-alpha with interferon-gamma (IFN-gamma) on different human breast cancer cell lines, particularly comparing hormone-dependent and -independent phenotypes. TNF-alpha inhibited the growth of hormone-dependent human MCF-7, ZR-75-1 and T47-D breast cancer cells with a half maximal concentration of 0.25 nM. In contrast, the growth of hormone-independent cells MDA-MB-231 and HS578T was not affected by TNF-alpha alone, but a synergistic inhibition was observed when using IFN-gamma and TNF-alpha together. The mRNA for the proto-oncogene C-MYC, as an intracellular indicator of cell activation, was significantly increased in MCF-7 cells in the presence of TNF-alpha. In MDA-MB-231 cells this mRNA was increased only in the presence of both TNF-alpha and IFN-gamma, without a change in the number of surface TNF receptors. These findings indicate that TNF-alpha treatment in combination with IFN-gamma may provide a successful approach to overcome the cellular heterogeneity of advanced breast tumours.

The dual role of mutant p53 protein in chemosensitivity of human cancers

Mutational loss of p53 tumor suppressor functions has been observed in a wide range of neoplasms and was associated with either enhanced or decreased chemosensitivity of affected tumors. The dual role of wild-type p53 as a DNA repair initiator and a trigger for apoptosis raises the possibility that appropriately designed chemotherapy could be selectively applied against p53-defective tumor cells. The cytotoxic effects of DNA-crosslinking chemotherapeutica such as cisplatin could be enhanced by mutated p53 which is no longer able to repair drug-induced DNA damage. In contrast, DNA synthesis blockers such as fluorouracil can induce apoptosis through p53-dependent mechanisms. Thus, loss of p53 functions results in decreased sensitivity to this type of drugs. Clinical studies will reveal the role of abberant p53 in the efficacy of chemotherapy for individual patients.

Chemiluminescence immunoassay for vascular endothelial growth factor (vascular permeability factor) in tumor-tissue homogenates

We developed a two-site chemiluminescence immunoassay for human vascular endothelial growth factor (VEGF). The assay recognized both VEGF121 and VEGF165 isoforms, but had no detectable cross-reactivity with platelet-derived growth factor or placenta growth factor. The range of detection was between 30 ng/L and 30 micrograms/L VEGF. Inter- and intraassay variations were 8.2-8.3% and 7.2-7.6%, respectively. VEGF concentrations were measured in the cytosolic extracts of 45 ovarian and 142 primary breast tumors. The amount of VEGF in the ovarian tumors (median = 0.46 ng/mg total protein, range 0-15.8 ng/mg) was significantly (P = 0.03) higher compared with the breast tumors (median = 0.24 ng/mg total protein, range 0-12.3 ng/mg). In 32 and 7 extracts of normal breast tissues adjacent and distant to the tumors, respectively, VEGF concentrations were significantly much lower (P < 0.0001). The detection of substantial amounts of VEGF in two invasive tumors (compared with normal tissues) suggests that the assay should be a useful tool for investigating the prognostic value of VEGF in breast and ovarian carcinomas and for selecting patients for future anti-VEGF therapy.

Chemiluminescence immunoassay for vascular endothelial growth factor (vascular permeability factor) in tumor-tissue homogenates

We developed a two-site chemiluminescence immunoassay for human vascular endothelial growth factor (VEGF). The assay recognized both VEGF121 and VEGF165 isoforms, but had no detectable cross-reactivity with platelet-derived growth factor or placenta growth factor. The range of detection was between 30 ng/L and 30 micrograms/L VEGF. Inter- and intraassay variations were 8.2-8.3% and 7.2-7.6%, respectively. VEGF concentrations were measured in the cytosolic extracts of 45 ovarian and 142 primary breast tumors. The amount of VEGF in the ovarian tumors (median = 0.46 ng/mg total protein, range 0-15.8 ng/mg) was significantly (P = 0.03) higher compared with the breast tumors (median = 0.24 ng/mg total protein, range 0-12.3 ng/mg). In 32 and 7 extracts of normal breast tissues adjacent and distant to the tumors, respectively, VEGF concentrations were significantly much lower (P &lt; 0.0001). The detection of substantial amounts of VEGF in two invasive tumors (compared with normal tissues) suggests that the assay should be a useful tool for investigating the prognostic value of VEGF in breast and ovarian carcinomas and for selecting patients for future anti-VEGF therapy.

Selective regulation of steroid receptor expression in MCF-7 breast cancer cells by a novel member of the heregulin family

A 52 kDa heregulin secreted by estrogen receptor (ER)-negative human breast cancer cells induced rapid growth of ER-positive MCF-7 breast cancer cells with a stimulatory effect observed at 10(-11)M. This heregulin down-regulated the message for ER in MCF-7 cells within 24 hours after stimulation. Similarly the ER protein was down-regulated within 24 to 48 hours after stimulation of cells. However, this down-regulation occurred without activation of the ER, since the progesterone receptor (PR) level of cells stimulated with the 52 kDa heregulin did not increase over the time period measured. As a control, estradiol down-regulated and activated ER as shown by a pronounced increase in PR content of MCF-7 cells. This finding indicates an important role of this heregulin in the down-regulation of ER in estrogen-dependent human breast cancer cells.

Isolation of a heregulin-like growth factor secreted by estrogen receptor-negative MDA-MB-231 human breast cancer cells that stimulates estrogen receptor-positive cells

A 52 kDa peptide growth factor secreted by the estrogen receptor (ER)-negative human breast cancer cell line MDA-MB-231 was purified to homogeneity. It induced transient membrane ruffling, lamellipodia formation, cell motility and proliferation exclusively of ER-positive human breast cancer cells. Partial sequencing revealed a high homology to the protein family of heregulins. However, the obtained amino acid sequences of the new factor were not completely identical to any of the members of the heregulin family. This finding together with the observation that the successful purification protocol was significantly different from that used to isolate other members of the heregulin family indicate the isolation of a novel heregulin-like proliferation factor for ER-positive human breast cancer cells.

Expression of Ca(2+)-binding proteins of the S100 family in malignant human breast-cancer cell lines and biopsy samples

In order to examine whether the expression of calcium-binding proteins of the S100 family may correlate with the transformation grade of human mammary-tumor cells, we studied the expression patterns of 4 members of this family (CACY, CAPL, S100L, S100 alpha/beta) in human breast-cancer cell lines. Each S100 protein is shown to be individually regulated in the human breast-cancer cell lines we studied, but it appears that the expression levels of S100 proteins do not strictly correlate with prognostic factors or the tumorigenicity of the cells. However, 2 aggressive cell lines, MDA-MB-231 and HS-578T, show elevated expression of CAPL. We show that methylation may account for partial regulation of the S100 genes, whereas neither genomic rearrangements in the S100 gene cluster region nor gene dosis effects seem to influence their expression pattern in MDA-MB-231 and MCF-7 cells. On the basis of our genomic analyses, we can localize the gene for S100L within 5 kb upstream of S100E, thus extending the S100 gene cluster by one gene. A series of primary breast tumors was collected and tested for expression of CAPL, CACY and S100 alpha/beta. The results show that all human breast-cancer tissues tested express CACY, whereas the presence of CAPL is more restricted. There is a significant correlation between enhanced expression of CAPL and presence of the invasivity marker urokinase-type plasminogen activator (uPA). This observation suggests that CAPL may play an important role in the acquisition of metastatic potential of human mammary epithelial cells.

Differential signal transduction of epidermal-growth-factor receptors in hormone-dependent and hormone-independent human breast cancer cells

In breast cancer, hormone dependency is inversely correlated with the number of surface epidermal-growth-factor (EGF) receptors on the tumor cells. In vitro, EGF stimulated only hormone-dependent immortalized human breast cancer cells to grow with an increased rate whereas hormone-independent cells were not affected by EGF. The number of EGF surface receptors is about 5-10-times smaller on hormone-dependent cells than on hormone-independent cells. Two cell lines representing the two cell types were used to demonstrate the signal-transduction capabilities of the EGF receptors. The two cell lines were the hormone-dependent MCF-7 cells and the hormone-independent MDA-MB-231 cells. Incubation at 37 degrees C for 15 min with 10(-8) M EGF increased the surface EGF-receptor density substantially on MCF-7 cells (50%) and reduced the number of these receptors on MDA-MB-231 cells to about 65% of the control. Both cell lines internalized a fluorescein-isothiocyanate-labeled EGF with similar kinetics. EGF triggered tyrosine phosphorylation of several targets in isolated MCF-7 cell membranes. One of these targets was shown by immunoprecipitation to be the EGF receptor. In MDA-MB-231 cell membranes, the EGF receptor was demonstrated to be the main target for tyrosine phosphorylation. The mRNA expression of the immediate early proto-oncogene c-fos was stimulated by EGF only in MCF-7 cells. In contrast, the mRNA of the EGF receptors was stimulated by EGF in both cell lines. These results demonstrate that, although EGF-binding sites are present on both cell lines, their signal-transduction capacity and activities are substantially different and resulted in a divergent response of the two cell types to EGF.

Growth factor receptors and their ligands

The understanding of the signal transduction cascade involving growth factors and their receptors is one major key for diagnostic and therapeutic improvements in human neoplasms. Using receptor autoradiography, an inverse relationship for the incidence of somatostatin receptors (SSR) and epidermal growth factor receptors (EGFR) was found in gliomas [1]. In the majority of low grade gliomas, SSR were present but EGFR were absent. In contrast, EGFR were present in most glioblastomas, but no SSR were detected. Recently, the amplification of the EGFR gene and its overexpression was demonstrated to be associated with the development of glioblastomas. Several independent reports revealed that 40-50% of tumors show amplified EGFR [2-4]. The frequency of EGFR amplification was directly associated with tumor malignancy. In addition, amplified EGFR levels indicate a bad prognosis and shorter overall survival [5]. Recent analysis of the EGFR gene in tumors has shown that regions of this gene frequently undergo alteration. Hence, not only amplification but also mutation may be the cause of the increased malignancy in EGFR overexpressing cells [6].

Purification of a factor from human peritoneal fluid that is able to immobilize spermatozoa

Human peritoneal fluid has been claimed to influence sperm motility. This report gives evidence for the presence in midcycle peritoneal fluid of a protein-bound, lipidic (hydrophobic) component able to immobilize spermatozoa as a function of time. This component was extracted from molecular weight-sieving and ion-exchange/high pressure liquid chromatography (HPLC)-purified peritoneal fluid fractions by either chloroform/methanol or charcoal treatments; resuspension of the chloroform/methanol extract with BWW-buffer and subsequent testing on spermatozoa resulted in sperm immobilization. Sequential or step-down chromatographic procedures (molecular weight-sieving-->cation-exchange-->anion-exchange HPLC separations of native peritoneal fluid) and extensive dialysis against double distilled water allowed the purification of the sperm immobilizing factor, as evidenced by the shorter incubation times necessary for sperm immobilization. Furthermore, the active fraction was found to immobilize spermatozoa without affecting its viability. Separation of the chloroform/methanol extracted immobilizing fraction on thin layer chromatography under conditions for phospholipid detection allowed the identification of a characteristic band which, after re-extraction, was found to be the sperm immobilizing substance. This factor does not contain choline, ethanolamine or serine. These results suggest that some lipidic peritoneal fluid components may influence sperm motility.

Inhibition of growth-factor-activated proliferation by anti-estrogens and effects on early gene expression of MCF-7 cells

Recently, it was reported that the anti-estrogen tamoxifen not only inhibits estradiol-stimulated growth of MCF-7 cells but also significantly reduces the proliferation rate of cells stimulated by growth factors. We have confirmed this finding and also shown that the new anti-estrogen droloxifene inhibits the proliferation of epidermal growth factor (EGF) and insulin-like growth factor-I (IGF-I)-stimulated MCF-7 cells. The growth-factor-induced proliferation was inhibited in a dose-dependent manner by the anti-estrogens in the complete absence of estrogen and FCS. Of the anti-estrogens, droloxifene was considerably more potent than tamoxifen. Because the expression of the proto-oncogenes c-fos and c-myc has been considered a key event in development of the mitogenic response, we examined the effects of anti-estrogens on c-myc and c-fos gene expression. We included in these investigations the steroidal anti-estrogen ICI 164,384 because this compound has no or very little estrogenic activity. The studies revealed that all 3 anti-estrogens transiently induced c-myc mRNA expression. However, the anti-estrogens inhibited estradiol-induced c-myc mRNA expression, although with different potencies. Pre-incubation of MCF-7 cells with droloxifene and tamoxifen resulted in elevated levels of growth-factor-induced c-myc mRNA expression. In contrast, the anti-estrogens did not induce c-fos mRNA or affect the expression of c-fos mRNA induced by growth factors. In conclusion, non-steroidal anti-estrogens inhibit growth-factor-stimulated proliferation of MCF-7 cells without inhibiting growth-factor-induced c-myc or c-fos mRNA expression.

c-fos, c-jun and c-myc expressions are not growth rate limiting for the human MCF-7 breast cancer cells

Insulin-like growth factor I (IGF-I) was 3 times more potent in pagating MCF-7 cell proliferation than epidermal growth factor (EGF). IGF-I stimulated c-fos mRNA expression about 5 times less than EGF. Both growth factors were equipotent in inducing c-jun and c-myc mRNA expressions. The protein level of c-Myc correlated with the mRNA level. IGF-I and EGF stimulated the transcriptional activity dependent on the phorbol 12-myristate 13-acetate-responsive element (TRE) to the same extent, when measured by the chloramphenicol acetyl transferase activity of a transiently transfected multiple TRE construct. These results strongly indicate that the expression levels of the measured proto-oncogenes do not correlate with the increase of growth stimulation by IGF-I and EGF and are not growth rate limiting for the human MCF-7 breast cancer cells.

Overexpression of the alpha-type protein kinase (PK) C in LLC-PK1 cells does not lead to a proportional increase in the induction of two 12-O-tetradecanoylphorbol-13-acetate-inducible genes

Phorbol esters, by activating protein kinase C (PKC), induce the expression of the urokinase-type plasminogen activator (uPA) gene and the proto-oncogene c-fos in LLC-PK1 (PK1) porcine kidney epithelial cells. To investigate the role of PKC in the regulation of these two 12-O-tetradecanoylphorbol-13-acetate (TPA)-inducible genes, the alpha-type PKC, the predominant subtype present in the PK1 cells, was overexpressed in this cell line. Two clonal PK1 derivatives overexpressing the alpha PKC 15- and 20-fold, respectively, were established. Compared with the parental and control cells, only a modest but substantially sustained (2- to 3-fold) increase in the accumulation of uPA as well as c-fos mRNAs were observed by TPA in these cells. These results indicate that the extent of induction of these genes mediated by TPA was not proportional to the amounts of alpha-type PKC stably overexpressed in these cells, suggesting that factor(s) downstream of the activation of the alpha PKC appear to be rate limiting for the induction of both TPA-inducible genes in PK1 cells.

Follicular fluid enhances sperm motility and velocity in vitro

Forty-three follicular fluids (FFs) obtained during laparoscopy were tested in vitro for their effect(s) on sperm motility using gametes obtained by the swim-up procedure. Both the proportion of motile sperm and the velocity distribution patterns were evaluated as function of time by multiple-exposure photography technique. At the various incubation periods considered, all FFs maintained or then enhanced sperm motility as compared with the paired control suspension incubated with a sperm survival medium. The results of the sperm contact test for FFs from women who achieved pregnancy versus FFs from women who remained infertile were not significantly different for both parameters measured. Comparing these with our previously reported results, we may hypothesize that FF released at ovulation into the peritoneal cavity may counteract some sperm-immobilizing effect of peritoneal fluid, thereby increasing the fertility potential of the male gametes.

Pharmacologic and biologic properties of droloxifene, a new antiestrogen

Pharmacologic investigations with droloxifene in vitro and in vivo revealed that droloxifene is a more efficient antiestrogen than tamoxifen. Droloxifene differs from tamoxifen in the following ways: it has a more than 10-fold higher binding affinity to the estrogen receptor; it shows lower estrogenic and higher antiestrogenic effects on rat uterus, indicating a higher therapeutic index; it more potently inhibits growth of various human ER-positive mammary carcinoma cell lines; short-term exposures with clinically relevant concentrations of droloxifene produce long-term growth inhibition of human ER-positive cancer cells and are more effective than continuous treatment with tamoxifen; it more effectively reduces S-phases and arrests ER-positive cells in G1-phase of the cell cycle; it antagonizes estrogen independent, growth factor stimulated proliferation of MCF-7 cells with higher efficiency; it blocks estrogen activated c-myc expression better than tamoxifen; it more effectively inhibits growth of various experimental tumors of animal (R 3230, DMBA) and human (T61) origin. Therefore, in all experimental systems, it was found that droloxifene is a more potent antiestrogen than tamoxifen.

Modulation of extracellular-matrix synthesized by cultured stromal cells from normal human breast tissue by epidermal growth factor

A routine, reproducible procedure was developed for the preparation and characterization of stromal cells from normal human breast tissue obtained by reduction mammaplasty. Isolates (n = 15) all exhibited enhanced rates of proliferation, even in the presence of 20% fetal calf serum, when exposed to epidermal growth factor or transforming growth factor a (both 10(-8) M). Cellular responsiveness to these growth factors was consistent with expression of specific surface receptors for epidermal growth factor (approximately 10(4)/cell). In cultures, stromal cells elaborated an extensive, cross-linked, insoluble extracellular matrix which remained firmly associated with the plastic surface of tissue culture ware upon lysis of cells. The insoluble matrix material was analyzed using enzymatic digestion procedures following incorporation of radiolabelled precursors into macromolecular material prior to lysis and preparation. The relative proportion of glycoconjugate (glycopeptides and proteoglycans) and collagenous material present in matrix material was approximately 45% and approximately 55%, respectively, and this was modulated by inclusion of epidermal growth factor into culture medium to approximately 60% and approximately 40%, respectively. Under similar culture conditions stromal cells synthesized twice as much hyaluronate as was produced by control cultures. By use of specific antibody preparations we identified at least four species of glycopeptide present in stromal matrices (namely, fibronectin, laminin, tenascin, and thrombospondin) as well as three types of collagen (types I, III, and IV). The rapid and reproducible procedure for the preparation of radiolabelled insoluble matrix material from normal human breast tissue allows for the study of cellular interaction involving extracellular matrix turnover and degradation.

Endothelin messenger RNA and receptors are differentially expressed in cultured human breast epithelial and stromal cells

Paracrine regulation is implicit in the biosynthesis and secretion of milk in the breast. An important determinant for this regulation in vivo is proximate cellular location as exemplified by stromal and epithelial cells in breast tissue. Cultured human breast epithelial cells exhibited low constitutive expression of mRNA for endothelin which was enhanced 20-fold after prolactin stimulation. Human breast stromal cells did not express measurable levels of endothelin mRNA under similar conditions. In a similar differential manner, the stimulated release of immunoreactive endothelin into medium overlay was observed only for breast epithelial and not stromal cells. Specific cell-surface receptors for endothelin and biochemical responsiveness to the peptide were observed only in the stromal cells.

Quantification of cells cultured on 96-well plates

The method for cell number measurement in monolayer cultures by crystal violet staining published recently by Gillies et al. (R. G. Gillies, N. Didier, M. Denton (1986) Anal. Biochem. 159, 109-113) was modified and significantly improved. The procedure was adapted for use in 96-well plates since the method is inherently very sensitive. Modifications allowed fast and complete solubilization of dye adsorbed by cell nuclei during staining. Since light absorption of the unstained or destained cell layers is negligible, cell number measurements can be performed in the respective wells. Due to these features, multiple assays may be carried out rapidly using standard 96-well plate readers. In addition, it is shown that the sensitivity of the assay can be varied and easily controlled by choosing the appropriate pH during the staining procedure. This increases the flexibility of the method making it useful for determining cell density of a wide range of different cell types.

Biosynthesis and posttranslational modifications of protein kinase C in human breast cancer cells

Several forms of protein kinase C with molecular masses of 74-, 77-, and 80-kDa were detected in subcellular fractions of human breast cancer MDA-MB-231 cells which express the alpha-type protein kinase C. Several lines of evidence indicated that the 74-kDa is the precursor of the 77- and 80-kDa protein kinase C forms. (i) Pulse-labeling experiments revealed that protein kinase C is synthesized on membranes as a 74-kDa protein that can be chased into the 77- and the 80-kDa protein kinase C forms. (ii) The primary translation product of protein kinase C displayed an apparent molecular size of 74-kDa as determined by in vitro translation of poly(A)+ RNA from MDA-MB-231 cells. (iii) Incubation with serine/threonine-specific protein phosphatases (potato acid phosphatase and phosphatase 1 or 2A) resulted in the complete dephosphorylation of the 77-kDa to the 74-kDa protein kinase C form. Protein kinase C appears to be synthesized in membranes as an unphosphorylated and presumably inactive 74-kDa form that is converted into the active 77- and 80-kDa protein kinase C by post-translational modification involving at least two phosphorylation steps. The first phosphorylation is probably achieved by a specific, yet unidentified, "protein kinase C kinase" since the 74-kDa protein kinase C species did not undergo autophosphorylation and was neither a substrate for the purified protein kinase C, S6 kinase, phosphorylase kinase, casein kinase II, nor for the catalytic subunit of cAMP-dependent protein kinase. Except for phosphorylase kinase and the catalytic subunit of the cAMP-dependent protein kinase, phosphorylation of the 77-kDa protein kinase C form with purified protein kinase C (autophosphorylation), S6 kinase or casein kinase II shifted the molecular mass of the 77-kDa protein kinase C to 80-kDa. Prolonged exposure of MDA-MB-231 cells to phorbol 12-myristate 13-acetate not only leads to a complete down-regulation of protein kinase C activity but also to an accumulation of 74-kDa protein kinase C due to a retarded conversion of the 74-kDa into the 77- and 80-kDa protein kinase C forms in these cells. Our data indicate that tumor promoters additionally interfere with the posttranslational processing that converts the 74-kDa protein kinase C precursor into the 77- and 80-kDa forms of the enzyme.