Knockdown of the small conductance Ca(2+) -activated K(+) channels is potently cytotoxic in breast cancer cell lines

BACKGROUND AND PURPOSE

Small conductance calcium-activated potassium (KCa 2.x) channels have a widely accepted canonical function in regulating cellular excitability. In this study, we address a potential non-canonical function of KCa 2.x channels in breast cancer cell survival, using in vitro models.

EXPERIMENTAL APPROACH

The expression of all KCa 2.x channel isoforms was initially probed using RT-PCR, Western blotting and microarray analysis in five widely studied breast cancer cell lines. In order to assess the effect of pharmacological blockade and siRNA-mediated knockdown of KCa 2.x channels on these cell lines, we utilized MTS proliferation assays and also followed the corresponding expression of apoptotic markers.

KEY RESULTS

All of the breast cancer cell lines, regardless of their lineage or endocrine responsiveness, were highly sensitive to KCa 2.x channel blockade. UCL1684 caused cytotoxicity, with LD50 values in the low nanomolar range, in all cell lines. The role of KCa 2.x channels was confirmed using pharmacological inhibition and siRNA-mediated knockdown. This reduced cell viability and also reduced expression of Bcl-2 but increased expression of active caspase-7 and caspase-9. Complementary to these results, a variety of cell lines can be protected from apoptosis induced by staurosporine using the KCa 2.x channel activator CyPPA.

CONCLUSIONS AND IMPLICATIONS

In addition to a well-established role for KCa 2.x channels in migration, blockade of these channels was potently cytotoxic in breast cancer cell lines, pointing to modulation of KCa 2.x channels as a potential therapeutic approach to breast cancer.

Role of endoplasmic reticulum stress induction by the plant toxin, persin, in overcoming resistance to the apoptotic effects of tamoxifen in human breast cancer cells

Background:

Persin is a plant toxin that displays synergistic cytotoxicity with tamoxifen in human breast cancer cell lines. Here, we examined the ability of persin to circumvent tamoxifen resistance and delineated the intracellular signalling pathways involved.

Methods:

The induction of apoptosis in tamoxifen-resistant and -sensitive breast cancer cells was measured by flow cytometry following treatment with persin±tamoxifen. Markers of endoplasmic reticulum stress (ERS) were analysed following treatment, and their causal role in mediating persin-induced apoptosis was determined using chemical inhibitors and RNA interference.

Results:

Cells that were resistant to an apoptotic concentration of tamoxifen maintained an apoptotic response to persin. Persin-induced apoptosis was associated with an increase in markers of ERS, that is, CHOP expression and XBP-1 splicing and was decreased by CHOP siRNA. The CASP-4 inhibitor Z-YVAD-FMK markedly inhibited persin-induced apoptosis in both tamoxifen-sensitive and -resistant cells.

Conclusion:

The cytotoxic effects of persin are CASP-4 dependent and mediated by CHOP-dependent and -independent ERS signalling cascades. Increased ERS signalling contributes to persin-induced reversal of tamoxifen resistance.

Abstract P2-06-19: Transferrin Receptor (CD71) Identifies Poor Response to Tamoxifen in Oestrogen Receptor Positive Breast Cancer Patients

Background: CD71 is involved in the cellular uptake of iron and is expressed on cells with high proliferation. Interestingly, we have Interestingly, we shown that its expression is associated with elevated tumour proliferation, shortened breast cancer specific survival and worsened outlook in ER+ adjuvant tamoxifen treated early breast cancer patients (Habashy et al, 2010). Here we extend our studies of the relationship between CD71 and tamoxifen outcome by study of an exploratory series of patients where endocrine response was directly assessable.

Material and Methods: CD71 (clone 10F11 antibody; Abcam, Cambridge, UK) and proliferation (MIB1) immunohistochemistry were performed as described in Habashy et al (2010) on 87 formalin fixed paraffin-embedded breast cancers. These were obtained from patients within the Nottingham Tenovus Multiple Antibody Study who had received systemic tamoxifen therapy for locally advanced primary carcinoma or metastatic disease or for recurrence after surgery alone. All had lesions assessable for response quality at 6 months, with survival and duration of antihormone response measured from initiation of antihormone to death or progression on therapy respectively. 48 tumours were classified as ER+ and 39 ER-. Results: Within this tamoxifen treated series, 68/87 patients were deemed positive for CD71 (plasma membrane and cytoplasmic), showing HScore values >=5. In the ER+ subgroup, a greater clinical response rate to tamoxifen was seen in CD71 — tumours (10 CR/PR, 3 S and 2 P) versus their CD71+ counterparts (CR/PR, 11 S and 16 P, p=0.015). CD71 positivity was associated with a significantly shortened time to progression and death (Kaplan Meier Test, p=0.026 and p=0.005 respectively). Examination of the proliferation marker MIB1 in ER+ tumours revealed a positive association with CD71 expression (Spearman's Test, p=0.01). In ER-patients, comprising predominantly progressive disease on tamoxifen therapy, CD71 status showed no impact on either time to progression of the disease or death.

Discussion: The present study extends our novel findings relating CD71 expression to loss of response to tamoxifen in ER+ breast cancer and reveals CD71 associates with increased tumour cell proliferation in clinical disease. Whether CD71 plays a causative role in the direction of these events and can be targeted to improve endocrine response requires to be ascertained.

Habashy HO et al, 2010, Breast Cancer Research and Treatment 119:283-293

Abd El-Rehim DM et al, 2005, Int J Cancer 116: 340-350

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P2-06-19.

A novel g.-1258G>A mutation in a conserved putative regulatory element of PAX9 is associated with autosomal dominant molar hypodontia

Mutations in the transcription factor PAX9 which plays a critical role in the switching of odontogenic potential from the epithelium to the mesenchyme during tooth development cause autosomal dominant non-syndromic hypodontia primarily affecting molars. Linkage analysis on a family segregating autosomal dominant molar hypodontia with markers flanking and within PAX9 yielded a maximum multipoint LOD score of 3.6. No sequence variants were detected in the coding or 5'- and 3'-untranslated regions (UTRs) of PAX9. However, we identified a novel g.-1258G>A sequence variant in all affected individuals of the family but not in the unaffected family members or in 3088 control chromosomes. This mutation is within a putative 5'-regulatory sequence upstream of PAX9 highly conserved in primates, somewhat conserved in ungulates and carnivores but not conserved in rodents. Bioinformatics analysis of the sequence determined that there was no abolition or creation of a putative binding site for known transcription factors. Based on our previous findings that haploinsufficiency for PAX9 leads to hypodontia, we postulate that the g.-1258G>A variant reduces the expression of PAX9 which underlies the hypodontia phenotype in this family.

Development of a food frequency questionnaire for the assessment of quercetin and naringenin intake

OBJECTIVES

To measure the relationship between quercetin and naringenin intakes as estimated by food frequency questionnaire (FFQ), and the urinary excretion of quercetin and naringenin aglycones after their enzymatic hydrolysis in human volunteers.

SUBJECTS AND METHODS

Volunteers were recruited via the Human Nutrition Unit volunteer databank at the Institute of Food Research, Norwich. Sixty-three volunteers were recruited into the study, of which 14 were excluded and 49 completed the study. A modified FFQ was developed and used to estimate daily intake of quercetin and naringenin in 49 healthy volunteers who also provided five 24-h urine samples over a 2-week period. Urinary excretion of quercetin and naringenin metabolites was determined by solid-phase extraction and high-pressure liquid chromatography.

RESULTS

The estimated mean intakes of quercetin and naringenin were 29.4 mg (s.d. 15.0) and 58.1 mg (s.d. 62.7) per day, respectively. Mean urinary excretion of quercetin was 60.1 microg (s.d. 33.1) and that of naringenin was 0.56 mg (s.d. 0.4). The correlation between FFQ estimated intake of quercetin and naringenin and levels excreted in the urine were r=0.82 (P<0.0001) and r=0.25 (P=0.05), respectively.

CONCLUSIONS

We observed a statistically significant correlation between the urinary excretion of quercetin and naringenin metabolites and their dietary intake as estimated by FFQ. Use of FFQs in epidemiological studies requiring an estimate of flavonoid intake seems justified.

Phosphorylation of ERalpha at serine 118 in primary breast cancer and in tamoxifen-resistant tumours is indicative of a complex role for ERalpha phosphorylation in breast cancer progression

Oestrogen receptor-alpha (ERalpha) is an important prognostic marker in breast cancer and endocrine therapies are designed to inhibit or prevent ERalpha activity. In vitro studies have indicated that phosphorylation of ERalpha, in particular on serine 118 (S118), can result in activation in a ligand-independent manner, thereby potentially contributing to resistance to endocrine agents, such as tamoxifen and aromatase inhibitors. Here we report the immunohistochemistry (IHC) of S118 phosphorylation in 301 primary breast tumour biopsies. Surprisingly, this analysis shows that S118 phosphorylation is higher in more differentiated tumours, suggesting that phosphorylation at this site is associated with a good prognosis in patients not previously treated with endocrine agents. However, we also report that S118 phosphorylation was elevated in tumour biopsies taken from patients who had relapsed following tamoxifen treatment, when compared to pre-treatment biopsies. Taken together, these data are consistent with the view that S118 phosphorylation is a feature of normal ERalpha function and that increases in levels of phosphorylation at this site may play a key role in the emergence of endocrine resistance in breast cancer.

Insulin-like growth factor-I receptor signaling and resistance in breast cancer

Insulin-like growth factor-I receptor (IGF-IR) signaling is involved in many fundamental adverse aspects of cancer cell biology, such as proliferation, cell survival and migration. Its anti-apoptotic properties have implicated the receptor in mediating decreased sensitivity to chemotherapeutic drugs and radiation treatment; however, data are emerging that also indicates a role for IGF-IR signaling in resistance, not only to antihormones but also to antigrowth factor strategies such as agents that target the erb family of receptors. As such, IGF-IR is clearly an attractive therapeutic target for the treatment of cancer, including breast cancer, where there is evidence of clinical prominence of the IGF-IR pathway and, as such, numerous strategies are currently in development to inhibit IGF-IR signaling. This review focuses on the ability of the IGF-IR to contribute to resistance mechanisms that support breast cancer cell growth in the presence of antihormones and antigrowth factors and discusses methods to maximize antitumor effects by combination regimens cotargeting the IGF-IR that may delay, or even prevent, progression to the resistant phenotype.

Epidermal growth factor receptor/HER2/insulin-like growth factor receptor signalling and oestrogen receptor activity in clinical breast cancer

Breast cancer models of acquired tamoxifen resistance, oestrogen receptor (ER)+ /ER- de novo resistance and gene transfer studies cumulatively demonstrate the increased importance of growth factor receptor signalling, notably the epidermal growth factor receptor (EGFR)/HER2, in tamoxifen resistance. Our recent in vitro studies also suggest that EGFR signalling productively cross-talks with insulin-like growth factor receptor (IGF-1R) and, where present, activates ER on key AF-1 serine residues to facilitate acquired tamoxifen-resistant growth. This paper presents our immunohistochemical evidence that EGFR/HER2 signalling (i.e. transforming growth factor (TGF)alpha, EGFR and HER2 expression; phosphorylation of EGFR, HER2 and ERK1/2 MAP kinase) is also prominent in clinical de novo resistant and modestly increased in acquired tamoxifen-resistant states, suggesting that anti-EGFR/HER2 strategies may prove valuable treatments. Primary breast cancer samples employed were obtained for (1) patients subsequently treated with tamoxifen for advanced disease where endocrine response and survival data were available and (2) ER+ elderly patients during tamoxifen response and relapse. We also present our clinical immunohistochemical findings that IGF-1R expression, its phosphorylation on tyrosine 1316, and also phosphorylation on serine 118 of ER are not only prominent in ER+ tamoxifen-responsive disease, but are also detectable in ER+ de novo and acquired tamoxifen-resistant breast cancer, where there is evidence of EGFR/ER cross-talk. Our data suggest that agents to deplete effectively ER or IGF-1R signalling may be of value in treating ER+ de novo/acquired tamoxifen resistance in addition to tamoxifen-responsive disease in vivo. IGF-1R inhibitors may also prove valuable in ER- patients, since considerable IGF-1R signalling activity was apparent within approximately 50% of such tumours.

Hydrolysis by lactase phlorizin hydrolase is the first step in the uptake of daidzein glucosides by rat small intestine in vitro

1. Isoflavones are naturally occurring oestrogenic compounds found in plants, where they exist in the glycosylated form. A proportion of ingested glycosides appears to be absorbed in the upper gastrointestinal tract, where enterocytes play an important role in their metabolism. 2. One hypothesis is that ingestion may involve hydrolysis by the luminally exposed enzyme lactase phlorizin hydrolase (LPH), an enzyme expressed specifically at the small intestinal brush border. 3. Using an everted sac preparation of rat jejunum and an inhibitor of LPH, we investigated the absorption of daidzein-O(7)-glucoside (daidzin) and the effect of LPH inhibition on this process. It was demonstrated that LPH plays a major role in the deglycosylation of daidzin. 4. The hydrolysis product, daidzein, is absorbed by epithelial cells and glucuronidated to daidzein-O(7)-glucuronide, which is subsequently exported primarily to the serosal (vascular) side of the tissue rather than to the luminal side. 5. A small but significant proportion of the intact glycoside is also transferred to the serosal compartment, and in the presence of an LPH inhibitor this was enhanced with a corresponding reduction in deglucosylation and glucuronidation. 6. The results indicate that that LPH plays an important role in the metabolism of glycosylated phytochemicals, and that the expression and activity of this enzyme in the small intestine can modify the profile of metabolites appearing in the circulation.

Evidence for consistent patterns between flavonoid structures and cellular activities

A wide variety of plant-derived compounds, including the polyphenolic flavonoids, is present in the human diet or is consumed for medicinal reasons. Epidemiological and animal studies tend to suggest a protective effect of flavonoids against cardiovascular diseases and some types of cancer. Although flavonoids have been studied for about 50 years, the cellular mechanisms involved in their biological activity are still largely unknown. Antioxidant properties of the flavonoids have been postulated as a mechanism for putative protective effect against cardiovascular disease. Nevertheless, these properties alone are not sufficient to explain the anti-carcinogenic potential of these polyphenols. The mechanisms by which the molecules interact with cells or are absorbed by them are very important for determining the intracellular concentration and distribution of the metabolites to internal organs. With the exception of the cells lining the gastrointestinal tract, all other cells in the body are only exposed to flavonoid metabolites and degradation products. No previous studies have addressed this aspect of cellular exposure, except for some methylated metabolites. Within the last decade, reports on flavonoid activities have been largely associated with enzyme inhibition and anti-proliferative activity. From our recent work on the human colon cancer cell line HT29 and comparison with published studies, structure-function relationships demonstrate that antioxidant, enzyme inhibitor or anti-proliferative activities are dependent on particular structure motifs. The present review also presents a summary of mechanistic data on a few elected compounds.

Prospects for combining hormonal and nonhormonal growth factor inhibition

In patients with estrogen receptor (ER)-negative disease or ER+ hormone-resistant disease, the dominant influence on tumor cell growth is growth factors, e.g., epidermal growth factor (EGF), heregulins, and insulin-like growth factors acting through specific receptor tyrosine kinases at the cell surface. This superfamily of ligand-activated growth factor receptors triggers cascades of biochemical signals that influence tumor cell motility, invasiveness, angiogenesis, and survival, as well as proliferation. In breast tumors, expression of epidermal growth factor receptor (EGFR) and/or erbB2 is associated with poor prognosis; the therapeutic utility of blocking these receptors has been established using trastuzumab (Herceptin), a monoclonal antibody that blocks erbB2 signaling. An alternative therapeutic approach is offered by small molecule inhibitors of EGFR-TK, exemplified by ZD1839 (Iressa), a potent and selective EGFR-TK inhibitor. Resistance to tamoxifen is associated with up-regulation of the EGFR-TK pathway and mitogen-activated protein kinase activity is substantially increased in tamoxifen-resistant MCF-7 cells. ZD1839 treatment of tamoxifen-resistant MCF-7 cells blocks mitogen-activated protein kinase activity. Furthermore, treatment of wild-type MCF-7 cells with tamoxifen and ZD1839 prevents development of tamoxifen resistance. These data support the potential clinical utility of ZD1839 in tamoxifen-resistant breast cancer and suggest the possibility of preventing resistance by the early use of combination ZD1839 with antiestrogenic agents such as tamoxifen or ICI 182,780.

TENB2, a proteoglycan identified in prostate cancer that is associated with disease progression and androgen independence

TENB2 encodes a putative transmembrane proteoglycan, related to the EGF/heregulin family of growth factors and follistatin, which has been identified through the application of a differential display technique to a xenograft model of prostate cancer. Northern analysis and competitive PCR were used to demonstrate significantly increased TENB2 expression (p = 0.0003) on the acquisition of androgen independence in the model system. TENB2 is also overexpressed in clinical prostate carcinoma vs. its benign counterpart (p < 0.0001), with particular prominence in high-grade tumours, and shows a high degree of tissue specificity, being detected on a multitissue Northern array exclusively in brain and prostate material. Studies of recombinant protein expression demonstrate that TENB2 is a chondroitin sulphate proteoglycan. The presence of an EGF and 2 follistatin domains suggests a role in the regulation of growth factor signalling either as a ligand precursor, a membrane-bound receptor or as a binding protein for growth factors. These data are indicative of a significant role for TENB2 in the progression of poorly differentiated tumour types, with implications for prostate cancer detection, prognosis and therapy.

Comparison of the short-term biological effects of 7alpha-[9-(4,4,5,5,5-pentafluoropentylsulfinyl)-nonyl]estra-1,3,5, (10)-triene-3,17beta-diol (Faslodex) versus tamoxifen in postmenopausal women with primary breast cancer

7Alpha-[9-(4,4,5,5,5-pentafluoropentylsulfinyl)-nonyl]estra-1,3,5, (10)-triene-3,17beta-diol (ICI 182,780; Faslodex) is a novel steroidal antiestrogen. This partially blind, randomized, multicenter study compared the effects of single doses of long-acting ICI 182,780 with tamoxifen or placebo on estrogen receptor (ERalpha) and progesterone receptor (PgR) content, Ki67 proliferation-associated antigen labeling index (Ki67LI), and the apoptotic index in the primary breast tumors of postmenopausal women. Previously untreated patients (stages T(1)-T(3); ER-positive or -unknown) were randomized and received a single i.m. dose of ICI 182,780 50 mg (n = 39), ICI 182,780 125 mg (n = 38), or ICI 182,780 250 mg (n = 44) or oral tamoxifen 20 mg daily (n = 36) or matching tamoxifen placebo (n = 43) for 14-21 days before tumor resection surgery with curative intent. The ER and PgR H-scores, together with the Ki67LI were determined immunohistochemically in the matched pretreatment biopsy and the posttreatment surgical specimens. The apoptotic index was determined by terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling on the same samples. The effects of treatment on each of these parameters were compared using analysis of covariance. ICI 182,780 produced dose-dependent reductions in ER and PgR H-scores and in the Ki67LI. The reductions in ER expression were statistically significant at all doses of ICI 182,780 compared with placebo (ICI 182,780 50 mg, P = 0.026; 125 mg, P = 0.006; 250 mg, P = 0.0001), and for ICI 182,780 250 mg compared with tamoxifen (P = 0.024). For PgR H-score, there were statistically significant reductions after treatment with ICI 182,780 125 mg (P = 0.003) and 250 mg (P = 0.0002) compared with placebo. In contrast, tamoxifen produced a significant increase in the PgR H-score relative to placebo, and consequently, all doses of ICI 182,780 produced PgR values that were significantly lower than those in the tamoxifen-treated group. All doses of ICI 182,780 significantly reduced Ki67LI values compared with placebo (ICI 182,780 50 mg, P = 0.046; 125 mg, P = 0.001; 250 mg, P = 0.0002), but there were no significant differences between any doses of ICI 182,780 and tamoxifen. ICI 182,780 did not alter the apoptotic index when compared with either placebo or tamoxifen. Short-term exposure to ICI 182,780 reduces the ERalpha in breast tumor cells in a dose-dependent manner by down-regulating ER protein concentration. The reductions in tumor PgR content by ICI 182,780 demonstrate that ICI 182,780, unlike tamoxifen, is devoid of estrogen-agonist activity. Reductions in tumor cell proliferative activity (as indicated by Ki67LI) show that ICI 182,780 is likely to have antitumor activity in the clinical setting.

Modulation of epidermal growth factor receptor in endocrine-resistant, oestrogen receptor-positive breast cancer

There is an increasing body of evidence demonstrating that growth factor networks are highly interactive with oestrogen receptor (ER) signalling in the control of breast cancer growth. As such, tumour responses to anti- hormones are likely to be a composite of the ER and growth factor inhibitory activity of these agents. The current article examines the modulation of growth factor networks during endocrine response, and presents in vitro and clinical evidence that epidermal growth factor receptor signalling, maintained in either an ER-dependent or -independent manner, is critical to anti- hormonal-resistant breast cancer cell growth. The considerable potential of the epidermal growth factor receptor-selective tyrosine kinase inhibitor, ZD 1839 (Iressa; AstraZeneca) to efficiently treat, and perhaps even prevent, endocrine-resistant breast cancer is highlighted.

EGFR and cancer prognosis

Elevated levels of the epidermal growth factor receptor (EGFR), a growth-factor-receptor tyrosine kinase, and/or its cognate ligands have been identified as a common component of multiple cancer types and appear to promote solid tumour growth. This article examines the relationship between EGFR expression and cancer prognosis based on literature compiled on PubMed between 1985 and September 2000. More than 200 studies were identified that analysed relapse-free-interval or survival data directly in relation to EGFR levels in over 20000 patients. Analysis of the data showed that 10 cancer types both express elevated levels of EGFR relative to normal tissues and have been studied in sufficient depth to allow sound judgements to be made concerning the association between EGFR and patient outlook. The EGFR was found to act as a strong prognostic indicator in head and neck, ovarian, cervical, bladder and oesophageal cancers. In these cancers, increased EGFR expression was associated with reduced recurrence-free or overall survival rates in 70% (52/74) of studies. In gastric, breast, endometrial and colorectal cancers, the EGFR provided more modest prognostic information, correlating to poor survival rates in 52% (13/25) of studies, while in non-small cell lung cancer (NSCLC), EGFR expression only rarely (3/10 studies) related to patient outlook. However, it is likely that the true prognostic significance of the EGFR has been underestimated as the published studies only assessed total cellular EGFR levels, rather than the activated form of the receptor, and were not standardised with regard to patient populations or assay methods. Finally, it is important to stress that failure to detect a prognostic significance for EGFR in any one cancer type does not necessarily preclude patients from benefiting from anti-EGFR therapies.

Polyphenolic compounds: interactions with the gut and implications for human health

Polyphenolic compounds are abundant throughout the plant kingdom and are found in a wide variety of human foods. The flavonoids, which are the best defined group of polyphenols in the human diet, themselves comprise a large and complex group, all of which contain a three-ring structure with two aromatic centres and a central oxygenated heterocycle. Recent evidence suggests that significant quantities of quercetin and possibly myricetin and kaempferol are absorbed in the gut. A larger fraction probably remains in the lumen, and thus a substantial proportion of the gastrointestinal mucosa is exposed to biologically significant concentrations of these compounds. A substantial body of experimental work has established that flavonoids can suppress carcinogenesis in animal models and there is considerable interest in the biological effects of these compounds at the cellular level. Flavonoids interact with cellular signal pathways controlling the cell cycle, differentiation and apoptosis. Their potentially antineoplastic effects include antioxidant activity, induction of Phase II enzyme activity, inhibition of protein kinases and interactions with Type II estrogen binding sites. Naturally occurring polyphenolic compounds may play a role in the protective effects of fruits and vegetables against cancers in general, and they appear to have considerable potential for pharmaceutical uses as chemopreventive agents against neoplastic changes in the alimentary tract. Future research should therefore focus on the biological effects of flavonoids in the human body, using biomarkers to define their effects at each stage in the onset of neoplasia.

Phosphorylation of ERK1/2 mitogen-activated protein kinase is associated with poor response to anti-hormonal therapy and decreased patient survival in clinical breast cancer

It is believed that growth factor phosphorylation cascades interact closely with oestrogen receptor (ER) signaling to regulate breast cancer growth, and that alterations in these pathways may underlie resistance to anti-hormones such as tamoxifen. There is an increasing body of experimental evidence implicating the mitogen-activated protein kinase extracellular signal-regulated-kinases ERK1 and ERK2 (ERK1/2 MAPK) in these events. The present study is the first to address the relationship between ERK1/2 MAPK phosphorylation (p-MAPK) and response to anti-hormonal agents in clinical breast cancer (n = 90). Immunocytochemical analysis using a phosphorylation state-specific ERK1/2 MAPK antibody revealed 72% of breast tumors to have considerable nuclear p-MAPK immunostaining (designated p-MAPK positive), whereas staining was barely detectable or absent in the remaining 28% (designated p-MAPK negative). Comparison with staining in normal breast material obtained from reduction mammoplasty patients (n = 10) demonstrated an increased frequency of higher intensity p-MAPK immunostaining cells within carcinomas (p = 0.002). Significant relationships were revealed between p-MAPK positivity and poorer quality (p = 0.001) and shortened duration (p = 0.006) of anti-hormonal response, as well as with decreased survival time from the initiation of therapy (p = 0.022). These associations were retained in ER positive disease (p = 0.013, p = 0.037 and p = 0.048 respectively), where multivariate analysis demonstrated p-MAPK status to be a significantly independent predictor for response duration (p = 0.034) and patient survival (p = 0.029). Phosphorylated ERK1/2 MAP kinase is thus potentially prognostic for prediction of response to anti-hormonal agents and survival, data providing further evidence that ERK1/2 MAP kinase plays a role in circumvention of anti-hormonal response in breast cancer.

Enhanced epidermal growth factor receptor signaling in MCF7 breast cancer cells after long-term culture in the presence of the pure antiestrogen ICI 182,780 (Faslodex)

This paper describes the establishment of an antiestrogen-resistant MCF7 breast cancer cell subline (FASMCF) by continuous culture of the estrogen-responsive parental line in steroid-depleted, ICI 182,780 (Faslodex; 10(-7) M)-supplemented medium. After a 3-month period of growth suppression, cells began to proliferate in ICI 182,780 at rates similar to those of untreated wild-type cells. Immunocytochemistry showed these cells to have reduced estrogen receptor and an absence of progesterone receptor proteins. RT-PCR and transient transfection studies with estrogen response element-reporter constructs confirmed that ICI 182,780-suppressed estrogen response element-mediated signaling. FASMCF cells show increased dependence upon epidermal growth factor receptor (EgfR)/mitogen-activated protein kinase (MAPK)-mediated signaling. Thus, EgfR protein and messenger RNA, growth responses to transforming growth factor-alpha, and extracellular signal-regulated kinase 1/2 MAPK activation levels are all increased. Unlike wild-type cells, FASMCF cells are highly sensitive to growth inhibition by an EgfR-specific tyrosine-kinase inhibitor (TKI), ZD1839 (Iressa), and an inhibitor of the activation of MEK1 (MAPKK), PD098059. Short-term ( approximately 3 weeks) withdrawal of cells from antiestrogen had no effect on growth or phenotype, whereas longer withdrawal (>10 weeks) appeared to partially reverse the cellular phenotype with increasing estrogen receptor and decreasing EgfR levels. In subsequent studies FASMCF cells were maintained in TKI, where their growth was again suppressed and secondary TKI resistance failed to develop within the 3-month period in which initial ICI 182,780 resistance arose. Furthermore, wild-type cells similarly maintained in combination ICI 182,780 and TKI treatment conditions remained growth arrested (>6 months), with notable cell loss through both reduced rates of cellular proliferation and increased cell death.

Effect of dietary GLA+/-tamoxifen on the growth, ER expression and fatty acid profile of ER positive human breast cancer xenografts

Gamma linolenic acid (GLA) possesses a number of selective anti-tumour properties including modulation of steroid receptor structure and function. We have investigated the effect of dietary GLA on the growth, oestrogen receptor (ER) expression and fatty acid profile of ER+ve human breast cancer xenografts. Experimental diets A, B, C, D were commenced after subcutaneous implantation of 40 female nude mice with the MCF-7 B1M cell line (Group A = control diet: B = control diet + GLA supplement: C = control diet + tamoxifen: D = control diet + GLA + tamoxifen; 10 mice/group). The mice were terminated when tumour cross-sectional area reached 250 mm(2). ER H-scores were assessed by immunohistochemical assay and fatty acid profiles by gas-liquid chromatography of termination tumour samples. Groups C and D displayed significantly slower tumour growth (p =.0002, p =.0006) with trend for slower growth in B (p =.065) compared to control Group A. ER was significantly reduced in all groups compared to A (p <.0001) with Group D (combined therapy) displaying markedly lower ER expression than with either therapy alone (p =.0002). There were significantly raised levels of tumour GLA and metabolites in the two groups (B and D) receiving GLA (p <.0001). This xenograft model of ER+ve breast cancer has demonstrated significantly lower tumour ER expression in those groups receiving GLA, an effect which appears to be additive to the reduced ER expression resulting from tamoxifen alone. The effects of GLA on ER function and the possibility of synergistic inhibitory action of GLA with tamoxifen via enhanced down-regulation of the ER pathway require further investigation.

Change in expression of ER, bcl-2 and MIB1 on primary tamoxifen and relation to response in ER positive breast cancer

Pre-treatment oestrogen receptor (ER) expression in breast cancer predicts for rate of response to endocrine therapy but not for the quality or duration of response (DofR). ER is known to be down-regulated by anti-oestrogens. This study has tested the hypothesis that the degree of down-regulation of ER and the ER-regulated marker bcl-2 are associated with the quality and duration of tamoxifen response. 80 patients with ER+ve breast cancer (H-score > 10) receiving primary tamoxifen (n = 51 Stage I-II elderly; n = 29 Stage III) underwent sequential tumour biopsies for immunocytochemical assessment of ER, bcl-2 and the proliferation marker MIB1. Median follow-up is 45 months. By 6-months on therapy three patients had attained complete response (CR), 27 partial response (PR); 44 static disease (SD) and six progression (PD) by UICC criteria. Greater decrease in ER and bcl-2 H-score from pre-treatment to 6 weeks (p = 0.035, p = 0.037) and ER and bcl-2 H-score from pre-treatment to 6 months (p = 0.058, p = 0.036) were significantly associated with better quality of response (CR/PR vs SD/PD). Greater 6-week and 6-month reduction in bcl-2 H-score (p = 0.041, p = 0.036) and 6-week reduction in MIB1 (p = 0.013) were significantly correlated with longer DofR. This study demonstrates that greater down-regulation of ER and the ER-regulated protein bcl-2 on primary tamoxifen are significantly associated with a better quality of response and bcl-2 and the proliferation marker MIB1 a longer duration of response in ER+ve breast cancer.

Increased induction of aberrant crypt foci by 1,2-dimethylhydrazine in rats fed diets containing purified genistein or genistein-rich soya protein

The isoflavonoid genistein inhibits mitosis and increases apoptosis in a variety of tumour cell lines in vitro, and may exert anticarcinogenic effects in vivo. To assess its effects on the colon, rats were fed a semi-synthetic control diet, or similar diets enriched with genistein (0.25 g/kg), either as the pure isoflavone or as part of a soya protein isolate, for 7 days before receiving subcutaneous injections of saline or 1,2-dimethylhydrazine (DMH). After 48 h, rats given saline were killed and samples of their small and large intestinal mucosa were obtained for assessment of crypt cell mitosis and apoptosis by visual analysis of isolated intact crypts. Rats given DMH were fed control diet and killed after 48 h for assessment of crypt cytokinetics or maintained for 42 days then killed and their colonic mucosa analysed for aberrant crypt foci (ACF). Two further groups were given control diet before DMH, followed by the genistein or soya-based diet for 42 days before assessment of ACF. Neither genistein nor soya protein isolate had a significant effect on crypt cell mitosis or apoptosis in untreated rats, or on the proliferative response to treatment with DMH. However, consumption of pure genistein or the soya protein isolate before treatment with DMH was associated with a 3-fold (P < 0.001) or 2-fold (P < 0.05) increase, respectively, in ACF in the distal colon. There was no significant effect of genistein or soya protein isolate given after DMH treatment. We conclude that genistein has no detectable effect on colonic crypt mitosis or apoptosis in the rat in vivo, but that it promotes induction of ACF by an as yet undefined mechanism when fed immediately before treatment with DMH.

Intestinal transport of quercetin glycosides in rats involves both deglycosylation and interaction with the hexose transport pathway

Flavonoids are polyphenolic plant secondary metabolites with antioxidant and other biological activities potentially beneficial to health. Food-borne flavonoids occur mainly as glycosides, some of which can be absorbed in the human small intestine; however, the mechanism of uptake is uncertain. We used isolated preparations of rat small intestine to compare the uptake of the quercetin aglycone with that of some quercetin glucosides commonly found in foods, and investigated interactions between quercetin-3-glucoside and the intestinal hexose transport pathway. The nature of any metabolism of quercetin and its glucosides during small intestinal transport in vitro was determined by HPLC. The presence of quercetin-3-glucoside in the mucosal medium suppressed the uptake of labeled galactose by competitive inhibition and stimulated the efflux of preloaded galactose. Quercetin-3-glucoside and quercetin-4'-glucoside, but not quercetin-3,4'-diglucoside, were transported into everted sacs significantly more quickly than quercetin aglycone. Intact quercetin glucosides were not detected in mucosal tissue or within the serosal compartment, but both free quercetin and its metabolites were present, mainly as quercetin-3-glucuronide and quercetin-7-glucuronide. Evidently, quercetin derived from quercetin-3-glucoside passes across the small intestinal epithelium more rapidly than free quercetin aglycone. Monoglucosides of quercetin interact with the sodium-dependent glucose transporter. During passage across the epithelium, quercetin-3-glucoside is rapidly deglycosylated and then glucuronidated.

Up-regulation of the protein tyrosine phosphatase SHP-1 in human breast cancer and correlation with GRB2 expression

The protein tyrosine phosphatase SHP-1 is predominantly expressed in hemopoietic cell lineages, where its function is relatively well defined. However, its expression profile also extends to certain epithelial cell types. Furthermore, the negative regulatory role of this enzyme in hemopoietic cell signaling may not apply to other systems, where positive effects on particular tyrosine kinase signaling pathways have been described. Expression of SHP-1 was therefore investigated in human breast cancer cell lines and primary breast cancers. Differential expression of SHP-1 mRNA was observed among the 19 breast cancer cell lines examined, and in an analysis of 72 primary breast cancers, SHP-1 mRNA expression was increased 2- to 12-fold relative to normal breast epithelial cells in 58% of the samples. Interestingly, a subset of the cancers also over-expressed GRB2 mRNA by 2- to 7-fold, and a significant (p < 0.01) positive correlation was observed between SHP-1 and GRB2 mRNA expression. Since these proteins can bind to each other and regulate MEK/MAP kinase activation, their co-ordinate up-regulation may amplify tyrosine kinase signaling in breast cancer cells.

Modulation of oestrogen action by receptor gene inhibition

Selective oestrogen receptor downregulators (SERDs) are a class of highly effective steroidal antitumour agents that reduce cellular levels of the oestrogen receptor (ER). In this study, we compared the efficacy by which three novel molecular approaches: (1) antisense oligonucleotides; (2) antisense RNA; and (3) dominant negative mutants are able to act as SERDs. Using transient and, where appropriate, stable gene transfection experiments we found that constitutive overexpression of ER antisense RNA and a hormone-binding domain compromised dominant-negative ER mutant (DNER-1), were most effective at downregulating ER expression and/or activity in vitro.

Biological and clinical associations of c-jun activation in human breast cancer

Sub-units and regulators of the activating protein-1(AP-1) complex have been implicated in breast-cancer biology, therapeutic response and prognosis. This study has immunocytochemically examined the impact of c-jun-protein activation on biological and clinical parameters in human primary breast cancers, employing an antibody specific for the serine 63-phosphorylated c-jun protein. Substantial nuclear immunostaining was commonly apparent, indicative of an activated c-jun pool, with associations with MAP-kinase-signalling elements, e.g., transforming growth factor-alpha (p = 0.04), epidermal growth factor receptor (p = 0.08), phosphorylated erk 1/2 MAP kinase (p = 0.001) and phosphorylated jun kinase (p = 0.05) Little association was noted with c-fos protein, perhaps indicating alternative AP-1 partners for c-jun with a diversity of cellular end-points. This may explain the lack of relationship with proliferation and grade, the imperfect association between increased c-jun activation and poorer survival (p = 0.061), and the apparent relationship with distant metastasis (p = 0.05). While increased c-jun activation related to poorer quality (p = 0.09) and shortened duration of endocrine response in oestrogen-receptor-positive patients (p = 0.018), no generalized effects on oestrogen-regulated gene products were noted, indicating that AP-1 influences on oestrogen-receptor/oestrogen-response element transactivation are unlikely to explain endocrine insensitivity. These data reinforce our belief that elevated AP-1 signalling influences aspects of the breast-cancer phenotype.

A possible divergent role for the oestrogen receptor alpha and beta subtypes in clinical breast cancer

We have examined the relative levels of oestrogen receptor beta (ERbeta) mRNA in 94 breast cancer specimens using a semi-quantitative RT-PCR procedure. We correlated its expression with ERalpha and various clinical, pathological and biochemical features of the disease. The level of ERbeta mRNA expression in these samples was found to be much lower than ERalpha. Although ERalpha mRNA species were found to be most frequently associated with histological grade I and II tumours, displaying tubular differentiation, low grades of nuclear pleomorphism and low mitotic activity, such features were not characteristic of ERbeta positive samples. Indeed, application of the Spearman rank correlation test revealed that there was an inverse association between ERbeta normalised levels and ERalpha protein HScore. Also ERbeta mRNA positive cancers were more frequently EGFR protein positive than their negative counterparts (p = 0.016), a feature normally associated with endocrine-insensitive disease. Our data suggest that although ERbeta levels are most likely lower than ERalpha, they may influence the biological behaviour of breast cancers containing low levels of ERalpha.

Gamma linolenic acid with tamoxifen as primary therapy in breast cancer

Gamma linolenic acid (GLA) has been proposed as a valuable new cancer therapy having selective anti-tumour properties with negligible systemic toxicity. Proposed mechanisms of action include modulation of steroid hormone receptors. We have investigated the effects of GLA with primary hormone therapy in an endocrine-sensitive cancer. Thirty-eight breast cancer patients (20 elderly Stage I-II, 14 locally advanced, 4 metastatic) took 8 capsules of oral GLA/day (total = 2.8 g) in addition to tamoxifen 20 mg od (T+GLA). Quality and duration of response were compared with matched controls receiving tamoxifen 20 mg od alone (n = 47). Serial tumour biopsies were taken to assess changes in oestrogen receptor (ER) and bcl-2 expression during treatment. GLA was well tolerated with no major side effects. T+GLA cases achieved a significantly faster clinical response (objective response vs. static disease) than tamoxifen controls, evident by 6 weeks on treatment (p = 0.010). There was significant reduction in ER expression in both treatment arms with T+GLA objective responders sustaining greater ER fall than tamoxifen counterparts (6-week biopsy p = 0.026; 6-month biopsy p = 0.019). We propose GLA as a useful adjunct to primary tamoxifen in endocrine-sensitive breast cancer. The effects of GLA on ER function and the apparent enhancement of tamoxifen-induced ER down-regulation by GLA require further investigation.

K-ras mutations, rectal crypt cells proliferation, and meat consumption in patients with left-sided colorectal carcinoma

It has been suggested that N-nitroso compounds derived from meat may increase the risk of K-ras mutations in the human colon. We sought evidence of associations between red meat consumption, frequency and type of K-ras mutations in resected tumours, and the rate of crypt cell proliferation (CCP) in the normal mucosa of patients with left-sided colorectal carcinoma. Meat consumption was assessed by food frequency questionnaire, and CCP was determined in rectal biopsies obtained prior to surgery. K-ras mutations in the resected tumours were determined using a PCR-based oligonucleotide hybridization assay. Fifteen K-ras mutations were detected in tumours from 43 patients; 13/15 in codon 12, 3/15 in codon 13, and 1/15 in both codons 12 and 13. All mutations were G-->A or G-->T transitions. There was no statistically significant difference between intakes of red meat in patients with a K-ras mutation (92.4 +/- 9.7 g/day) and those without (82.3 +/- 7.7 g/day). Rectal CCP was significantly higher in patients than in healthy controls, but there was no correlation with meat consumption or K-ras mutation. These data do not support the hypothesis that meat consumption is a risk factor for acquisition of K-ras mutations during colorectal carcinogenesis.

Immunohistochemical analysis reveals a tumour suppressor-like role for the transcription factor AP-2 in invasive breast cancer

This paper describes the generation and characterization of a monoclonal antibody specific for two members of the AP-2 family of transcription factors, AP-2alpha and AP-2beta, and its subsequent application to archival primary breast tumour material. Nuclear localization of AP-2 was found in all expressing cases, but in general levels of immunostaining were low, with only 17 per cent of the 86 tumours examined showing very high expression levels. Nevertheless, data analysis of the whole patient series allowed the identification of significant relationships between levels of AP-2 and other important breast markers. Thus, expression of AP-2alpha/beta was found to correlate significantly with expression of both ER ( p=0.036*) and the universal cell-cycle inhibitor p21(cip) ( p=0.03*), but was inversely related to levels of the proto-oncogene ErbB2 ( p=0.008*). AP-2-positive tumours also showed a low rate of proliferation, with significantly reduced mitotic count and a lower tumour grade. There was no significant relationship with clinical parameters, but samples with adjacent normal tissue indicated that loss of the AP-2 marker was associated with disease progression from normal breast through to invasive disease. This was confirmed by examining separate series of pure normal and pure DCIS samples, both of which expressed significantly higher levels of AP-2 ( p=0.0001* in each case) than the invasive tumours. Overall, these findings implicate AP-2alpha/beta as having a role akin to that of a tumour suppressor in breast cancer.

Consumption of fish oil leads to prompt incorporation of eicosapentaenoic acid into colonic mucosa of patients prior to surgery for colorectal cancer, but has no detectable effect on epithelial cytokinetics

Fish oil (FO) was previously reported to partially normalize colorectal crypt cell cytokinetics in patients with colorectal neoplasms. We determined the effect of FO on the fatty acid composition of colonic mucosa and mesenteric adipose tissue and on rectal crypt cell proliferation in patients undergoing surgery for colonic carcinoma. Patients (49-28 males; 21 females) were randomly assigned to consume FO capsules (2 g b.d.; FO group) containing 1.4 g eicosapentaenoic acid (EPA) and 1.0 g docosahexaenoic acid per day, or safflower oil capsules (2 g b.d.; placebo group) for an average of 12.3 +/- 0.5 d prior to surgery. Rectal biopsies were obtained at entry, at surgery, and 8-12 wk postsurgery. Colonic biopsies and samples of mesenteric adipose tissue were analyzed for fatty acids by gas-liquid chromatography. Mitosis was determined in whole crypt mounts. The proportion of EPA (g/100 g total fatty acids) in mucosal lipids was significantly greater in FO patients compared to the placebo group, but there was no effect on mesenteric adipose tissue. However self-reported use of FO supplements prior to surgery was associated with higher levels of EPA in adipose tissue. There was no significant effect of FO on the frequency or spatial distribution of crypt cell mitosis. EPA from marine oil supplements is rapidly incorporated into the colonic mucosal lipids of humans, but the levels achieved in the present study did not modify colorectal cytokinetics.

Involvement of steroid hormone and growth factor cross-talk in endocrine response in breast cancer

Multiple lines of evidence implicate steroid hormone and growth factor cross-talk as a modulator of endocrine response in breast cancer and that aberrations in growth factor signaling pathways are a common element in the endocrine resistant phenotype. Delineation of these relationships is thus an important diagnostic goal in cancer research, while the targeting of aberrant growth factor signaling holds the promise of improving therapeutic response rates.

Overexpression of cyclin D1 messenger RNA predicts for poor prognosis in estrogen receptor-positive breast cancer

Cyclin D1 is a key cell cycle regulatory protein with demonstrated oncogenic activity in a variety of malignancies. Cyclin D1 mRNA and protein are overexpressed in approximately 50% of primary breast carcinomas; however, the pathophysiological consequences of increased expression remain unclear. To investigate the functional sequelae of cyclin D1 mRNA overexpression, we analyzed clinical outcome in relation to the cyclin D1 mRNA level in 253 primary breast cancer patients (median follow-up, 75 months) with particular reference to estrogen receptor (ER) status and endocrine response. Overall, with the exception of the relationship between cyclin D1 mRNA expression and the ER, cyclin D1 mRNA was not associated with other clinicopathological features such as age, menopausal status, axillary lymph node status, vascular invasion, tumor size, type, and grade. However, in patients with ER-positive tumors (n = 182), high levels of cyclin D1 mRNA were associated with increased risk of relapse (P = 0.0016), local recurrence (P = 0.025), metastasis (P = 0.019), and death (P = 0.025). In contrast, there were no clinical correlations with cyclin D1 expression in ER-negative disease (n = 71). In 33 patients who received endocrine therapy for their primary or recurrent breast cancers, there was an apparent association between a high cyclin D1 mRNA level and a shorter response duration within the ER-positive subgroup (P = 0.04). Our findings indicate that overexpression of cyclin D1 mRNA correlates with a worse prognosis within the ER-positive breast cancer phenotype and may be a contributing factor to the development of endocrine resistance in ER-positive disease.

BRCA1 expression levels predict distant metastasis of sporadic breast cancers

The role of BRCA1 in progression of sporadic breast cancers has to date been equivocal, although preliminary studies on small numbers of samples have suggested an association between expression levels of this gene and acquisition of an invasive phenotype. We have further reasoned that loss of oestrogen receptor positivity may have a detrimental effect on BRCA1 expression. In order to test this hypothesis and extend earlier investigations we have applied a sensitive RT-PCR procedure to determine the associations between BRCA1 expression and a variety of clinical parameters in a sample cohort derived from sporadic breast tumour specimens. We have established that BRCA1 and ER mRNA expression are closely associated (p=0.013), indicating a possible functional relationship between these 2 genes. We have further identified an association between low levels of BRCA1 expression and acquisition of distant metastasis in sporadic disease (p=0.019). In light of our findings, we suggest that suppression of BRCA1 has a role to play in progression of a significant fraction of sporadic breast cancers and may additionally prove to be a useful, novel, prognostic marker for this disease type.

p21(WAF1) expression and endocrine response in breast cancer

An immunocytochemical assay for the p53-regulated protein product of the WAF1/Cip1 gene, p21(WAF1) (p21), was developed and applied to archival primary breast tumour material from 91 patients whose subsequent recurrent disease was treated with assessable courses of endocrine therapy. Nuclear localization of p21 protein was observed in 76 (82.4 per cent) cases. Status cut-offs were established and 29 (31.9 per cent) were deemed negative, 39 (42.9 per cent) weakly positive, and 23 (25.3 per cent) strongly positive. p21 status was inversely correlated with p53 protein (p=0.047) but did not relate to oestrogen receptor (ER) status, response to endocrine therapy, or time to further disease progression (TTP). Highly p21-positive patients had a significantly improved overall survival time (p=0. 020). Co-assessment of p21 and p53 subgroups revealed p21+/p53- patients to have good survival characteristics, whilst p21-/p53+ patients did poorly (p=0.008). The p21-/p53- patients overall did intermediately well, but Ki67-defined cellular proliferation analysis of these revealed two subclasses: those with high proliferation and poor survival times resembling the p21-/p53+ phenotype, and those with less proliferative tumours with good survival, similar to the p21+/p53- group. The significance of these results is discussed in the light of recent research concerning the role of p21 and p53 in breast cancer aetiology.

The immunohistochemical expression of desmoplakin and its role in vivo in the progression and metastasis of breast cancer

Desmoplakin (DP) is a protein located at the inner plaque of desmosomes where it associates with the desmosomal cadherins to form a cell adhesion complex. Reduced expression of DP has been correlated with the progression of several cancers, but its role in in vivo breast cancer is yet to be established. The aim of this present paper was to determine the immunohistochemical (IHC) expression of DP in breast cancer specimens (n = 75) in comparison with ductal carcinoma in situ (DCIS) (n = 26), tumour associated normal (n = 29) and normal breast tissue (n = 7). DP expression was correlated with that of desmosomal cadherin, Desmoglein 2 (Dsg2) and other clinical and IHC prognostic markers. DP staining occurred at the sub-plasma membrane level. There was no significant correlation between the level of DP (as assessed by the H-score) and that of Dsg. Significantly stronger staining was demonstrated in normal breast tissue and well differentiated tumours compared with more moderately or poorly differentiated tumours (P = 0.04). A significant inverse correlation was seen between DP staining and tumour size (P = 0.01). In a limited series of 8 cases, primary tumours demonstrated significantly stronger staining than the matched metastatic lymph nodes (P = 0.046). Of all the IHC markers examined, only Ki-67 showed a significant inverse relationship with DP staining (P = 0.01). In summary, the data suggest that loss of DP may be of potential importance in progression of breast cancer in vivo from normal, DCIS, well differentiated through to poorly differentiated, large tumours. In addition, this loss may be associated with metastasis.

Endocrine response and resistance in breast cancer: a role for the transcription factor Fos

We have previously demonstrated that elevated Fos expression may be important in de novo endocrine resistance in breast cancer. However, changes in Fos expression during endocrine response and subsequently on acquisition of resistance are unknown. This study immunocytochemically monitors Fos protein within sequential biopsies from primary human breast cancer patients obtained pre-treatment (T1), during tamoxifen therapy (T2, T3) and on disease progression (T5), examining in parallel proliferation [i.e., MIBI (Ki67) immunostaining, mitotic activity], cellularity and endocrine response. Significantly diminished Fos, proliferation and cellularity were observed after 6 weeks of therapy in patients exhibiting a better quality and/or duration of response, while modest Fos increases and a maintained proliferation and cellularity were seen in poorer responders. Decreases in Fos, proliferation and cellularity at 6 months similarly hallmarked better responders. We confirmed a significant association between de novo resistance and elevated Fos and proliferation. Additionally, however, these parameters increased at the time of disease relapse over pre-treatment and "on therapy" values. Our data indicate that tamoxifen response involves a reduction in both tumor cell proliferation and cell survival, potentially entailing diminished Fos protein expression in better-responding patients. Our data are also supportive of elevated Fos expression being involved in the departure from endocrine control inherent in both primary and acquired resistance.

c-erbB3 and c-erbB4 expression is a feature of the endocrine responsive phenotype in clinical breast cancer

We examined c-erbB3 and c-erbB4 mRNA expression in 47 primary breast cancer samples by simultaneous RT-PCR and have investigated correlations between these parameters and the expression of both ER and EGFR mRNA and protein as measured by RT-PCR and ICA and with Ki67 immunostaining. A direct association was found between c-erbB3 and c-erbB4 mRNA and ER marker status measured by either RT-PCR (c-erbB3 P = 0.0003; c-erbB4 P = 0.02) or ICA (c-erbB-3 P = 0.002; c-erbB4 P = 0.01). Inverse associations were seen between c-erbB3 and c-erbB4 mRNA marker status and EGFR membrane protein (c-erbB3: P = 0.003; cerbB4: P = 0.003) and mRNA (c-erbB4: P = 0.009) status. These associations were reinforced by Spearman Rank Correlation Tests. A significant relationship was seen between Ki67 and c-erbB4 mRNA status and level. Measurements of c-erbB3 protein levels in tumour samples removed from a further 89 patients of known response to endocrine therapy: (i) confirmed the relationship between c-erbB3 and ER and (ii) identified that patients whose ER positive tumours expressed high levels of c-erbB3 were most likely to benefit from endocrine measures. A non-significant trend was recorded between c-erbB3 levels and Ki67 immunostaining. These results clearly demonstrate that increased c-erbB3 and c-erbB4 expression appears to be associated with the prognostically-favourable ER phenotype.

C-erbB2 expression predicts response to preoperative chemotherapy for locally advanced breast cancer

BACKGROUND

Previous work suggests that the presence of c-erbB2 oncoprotein immunostaining and the proliferation rate of tumours, may be relevant to chemo-sensitivity in breast cancer.

PATIENTS AND METHODS

To investigate this we assessed pretreatment biopsies from 50 patients with locally advanced breast cancer for expression of c-erbB2 and MIB1 (proliferative marker) in relation to clinical response after 3 months preoperative chemotherapy.

RESULTS

Objective response was significantly more likely (22/30, 73%) for tumours negative for c-erbB2 membrane staining, compared to positively staining tumours (6/20, 30%, p = 0.0025). The percentage of cells staining positively for MIB1 was not predictive of response (p = 0.56).

CONCLUSIONS

This study has shown an increased likelihood of response to preoperative chemotherapy for breast cancers negative for c-erbB2 staining. Previous studies have shown that c-erbB2 immunostaining can correlate with either chemo-resistance or chemo-response. We postulate that this conflict may be due to differences in the type of chemotherapy administered. This raises the possibility of biological markers being use to assist in the selection of the type of chemotherapy regimen administered to particular tumour biological phenotype.

Quercetin glucosides interact with the intestinal glucose transport pathway

Flavonols are efficient antioxidants with the potential to protect biological macromolecules from oxidative damage in vivo, and if absorbed into the circulation they may protect against cardiovascular disease. Although flavonol aglycones are present in foods at low concentrations, their glycosides are abundant in onions, apples, beans and tea, and are thought to be stable under the conditions of the human stomach and small bowel. There is, however, recent evidence to suggest that intact glycosides of quercetin may be absorbed from the small intestine by a mechanism involving the glucose transport pathway. In the present study we tested this hypothesis by measuring the effect of quercetin glycosides on the rate of efflux of galactose from the jejunal mucosa. Everted sacs of rat jejunum preloaded with 14C-galactose were exposed to quercetin glycosides isolated from onions. Quercetin mono- and diglucosides were shown to accelerate the carrier-mediated efflux of galactose via a sodium-dependent pathway. HPLC analysis confirmed the stability of the glycosides under conditions simulating those in the upper alimentary tract. These studies suggest that purified quercetin glucosides are capable of interacting with the sodium dependent glucose transport receptors in the mucosal epithelium and may therefore be absorbed by the small intestine in vivo.

Oestrogen-regulated genes in breast cancer: association of pLIV1 with response to endocrine therapy

Northern hybridization analyses of the oestrogen-inducible mRNAs pLIV1 and pS2 were compared with oestrogen receptor (ER) immunocytochemistry assessments in 40 untreated primary or early recurrent breast tumours. Significant associations were observed between pLIV1/ER (P < 0.03), pS2/ER (P < 0.001) and pLIV1/pS2 (P < 0.04) status. After disease recurrence, patients were treated with assessable courses of endocrine therapies. Positive pLIV1, pS2 and ER statuses in primary disease were consequently found to be predictive of endocrine responsiveness in the secondary lesions (P < 0.03, P < 0.02, P < 0.005 respectively). However, despite these associations, a number of pLIV1- and/or pS2-positive tumours failed to respond to therapy.

Use of reverse transcription-polymerase chain reaction methodology to detect estrogen-regulated gene expression in small breast cancer specimens

We describe the development and use of a sensitive reverse transcription-PCR (RT-PCR) procedure to detect novel estrogen-regulated gene expression in small clinical breast cancer samples, in which such study would be extremely difficult by any other molecular or immunocytochemical means. Assay optimization for pLIV1, estrogen receptors (ERs), progesterone receptors, and pS2 gene products was carried out on 50 primary breast cancers for which comparative Northern analysis and immunocytochemical data were available. Using 27 amplification cycles and a 0.5 microM primer concentration, varying expressions of the gene products were recorded simultaneously with a constant densitometric signal for a coamplified endogenous control gene (alpha-actin). Good concordances were subsequently observed between pLIV1 status generated by RT-PCR and both Northern analysis (P = 0.002) and ER status by immunocytochemistry (P = 0.0244). Agreement was also noted between ER (P = 0.002), progesterone receptor (P = 0.0005), and pS2 (P = 0. 0023) RT-PCR and immunocytochemical methodologies. The RT-PCR assays were then applied to 10 needle core trucut biopsies in which similar relationships were obtained. Our results justify the future use of this RT-PCR methodology to examine new estrogen-regulated genes in small breast cancer samples, and it is envisaged that this technology will prove invaluable in many future breast cancer studies.

Soluble non-starch polysaccharides derived from complex food matrices do not increase average lipid droplet size during gastric lipid emulsification in rats

The creation of a finely dispersed lipid emulsion is essential for efficient hydrolysis of dietary triglycerides. The effectiveness of emulsification within the stomach depends upon the shear force generated by gastric motility and the concentration of emulsifiers present in the gastric contents. Other dietary constituents can modify these factors, and previous studies have suggested that the presence of soluble non-starch polysaccharides (NSP) during digestion might increase the average size of intraluminal emulsion droplets. In the present study, we developed a new technique for the isolation and analysis of intraluminal lipid emulsions by optical diffraction analysis. The method was applied to rats fed powdered semipurified diets that were free of all NSP or supplemented with insoluble cellulose, guar gum, or NSP derived from apple, carrot or rolled oats. Cellulose had no significant effect on emulsion size, and there was no evidence that the average sizes of lipid droplets in the gastric fundus or antrum were higher than control values in rats fed diets supplemented with any source of soluble NSP. In the groups fed oats and cooked carrot NSP, the mean droplet diameters approached half the values for diets free of NSP or containing insoluble cellulose. The difference between rats fed NSP from cooked carrot and those fed cellulose was significant in the proximal stomach (P < 0.05), and that between rats fed raw oats and rats fed cellulose was significant in the distal stomach (P < 0.05). Soluble dietary fiber does not inhibit lipid or cholesterol absorption via any inhibition of lipid emulsification.

Comparative studies of the mitogenic effects of epidermal growth factor and transforming growth factor-alpha and the expression of various growth factors in neoplastic and non-neoplastic prostatic cell lines

BACKGROUND

The role of growth factors in prostate cell growth has been investigated as these peptides may be involved in the autonomous growth of hormone-independent prostate cancer.

METHODS

Responses of neoplastic (PC-3 and CPA) and non-neoplastic (CAPE) prostatic cell lines to epidermal growth factor (EGF) and transforming growth factor-alpha (TGF-alpha) were determined using clonogenic and growth curve analysis. The constitutive expression of EGF, TGF-alpha, and TGF-beta 1-3 mRNA was examined using Northern blotting and EGF and TGF-alpha protein levels were determined immunohistochemically.

RESULTS

Growth curve and clonogenic analysis indicated that EGF and TGF-alpha were mitogenic in each cell line. The magnitude of the clonogenic response varied between the cell lines, with CPA cells showing the greatest growth increases. CPA cells also displayed the highest levels of EGF and TGF-alpha mRNA and protein. TGF-beta 1 mRNA was detected in the order of magnitude, PC-3 > CPA > CAPE. Furthermore, PC-3 and CPA cells expressed TGF-beta 3 and TGF-beta 2 transcripts respectively. In each cell line, the expression of any growth factor mRNA was not affected by exogenous EGF.

CONCLUSIONS

The growth responses of the cell lines to EGF and TGF-alpha did not correlate with their constitutive levels of EGF and TGF-alpha mRNA and protein, thus whilst growth factors may be important in malignant cell growth, other pathways may also be involved in the autocrine regulation of cell proliferation.

Effect of saponin on the transmucosal passage of beta-lactoglobulin across the proximal small intestine of normal and beta-lactoglobulin-sensitised rats

The ability of saponins and glycoalkaloids to permeabilise the mammalian intestinal barrier has been previously demonstrated in vitro, leading to the hypothesis that membranolytic saponins may facilitate transfer to the tissues of otherwise excluded macromolecules. An enhanced uptake of, for instance, potentially allergenic species from the lumen is one of the factors that may affect the induction of food allergy, and its presentation in already sensitised individuals. In the experiments described here, an increase in the transmucosal uptake of the milk allergen beta-lactoglobulin (beta LG) was assessed in non-sensitised and sensitised Brown Norway rats in the presence of Gypsophila saponin. Isolated jejunal loops were exposed in vivo to either beta LG followed by saponin, saponin followed by beta LG or the two compounds simultaneously. Portal vein blood samples were collected and assayed for beta LG and rat mucosal mast cell protease (RCMP II) activity. Mucosal tissue was also examined histologically and assayed for histamine content. Sham-operated animals, exposed to physiological buffer alone, were included as controls and beta LG measurements corrected for this component which was negligible. No transfer of beta LG occurred in the absence of saponin in non-sensitised rats, whereas a significant enhancement was observed in the presence of saponin. beta LG was detected in the portal circulation of sensitised rats exposed to beta LG alone; however addition of saponin to the intestinal lumen further enhanced this uptake, possibly by an independent mechanism. Histological examination of the mucosal epithelium exposed to saponin revealed damage, especially at the villus tips. Mucosal histamine and serum RCMP II concentrations were consistent with the differences observed between sensitised and non-sensitised animals. It is concluded that exposure to food constituents capable of permeabilising the mucosal epithelium may increase the risk of sensitisation to dietary antigens.

Fermentable carbohydrate modulates postprandial enteroglucagon and gastrin release in rats

We studied the effects of a fermentable sugar-alcohol (lactitol) on the concentrations of enteroglucagon and gastrin in the blood of rats for 7.5 h after feeding. The control and treatment groups were fed on semi-purified diets containing either non-fermentable cellulose or lactitol respectively, at 100 g/kg. Compared with the cellulose-fed group, the animals fed with lactitol had higher levels of enteroglucagon (5-10 times higher than control; P < 0.05) and lower serum gastrin (70-80% of control; P < 0.05) for several hours after the withdrawal of feed. In contrast, varying the level of dietary lipid (maize oil) over a range of 8-120 g/kg had no effect on the release of either peptide. These results suggest that poorly absorbed fermentable dietary carbohydrate stimulates postprandial plasma enteroglucagon and inhibits serum gastrin release in the rat. The mechanism is uncertain but an endocrine response by the colon to fermentation products seems probable.