Gene regulatory networks: a new conceptual framework to analyse breast cancer behaviour.

The study of complex systems has clearly evidenced that a few overall behavioural properties cannot be inferred from the properties of their single parts and are rather determined by their architecture. Such an approach has been recently proposed in biology to understand genome functioning and in oncology to endeavour a more consistent explanation of the variegated cancer behaviours. In the present perspective, we summarise the basic concepts of the proposed global approach and then we reconsider, in this new context, tumour dormancy and primary tumour removal effects, which recently emerged as critical points for breast cancer understanding.

An immunohistochemically positive E-cadherin status is not always predictive for a good prognosis in human breast cancer.

BACKGROUND: in primary breast cancers dichotomic classification of E-cadherin expression, according to an arbitrary cutoff, may be inadequate and lead to loss of prognostic significance or contrasting prognostic indications. We aimed to assess the prognostic value of high and low E-cadherin levels in a consecutive case series (204 cases) of unilateral node-negative non-lobular breast cancer patients with a 8-year median follow-up and that did not receive any adjuvant therapy after surgery. METHODS: expression of E-cadherin was investigated by immunohistochemistry and assessed according to conventional score (0, 1+, 2+, 3+). Multiple correspondence analysis was used to visualise associations of both categorical and continuous variables. The impact of E-cadherin expression on patients outcome was evaluated in terms of event-free survival curves by the Kaplan-Meier method and proportional hazard Cox model. RESULTS: respect to intermediate E-cadherin expression values (2+), high (3+) or low (0 to 1+) E-cadherin expression levels had a negative prognostic impact. In fact, both patients with a low-to-nil (score 0 to 1+) expression level of E-cadherin and patients with a high E-cadherin expression level (score 3+) demonstrated an increased risk of failure (respectively, hazard ratio (HR)=1.71, confidence interval (CI)=0.72-4.06 and HR=4.22, CI=1.406-12.66) and an interesting association with young age. CONCLUSIONS: the findings support the evidence that high expression values of E-cadherin are not predictive for a good prognosis and may help to explain conflicting evidence on the prognostic impact of E-cadherin in breast cancer when assessed on dichotomic basis.

A prediction model for breast cancer recurrence after adjuvant hormone therapy.

Hormone therapy with tamoxifen has long been the established adjuvant treatment for node-positive, estrogen-receptor-positive breast cancer in postmenopausal women. Since 30-40% of these patients fail to respond, reliableoutcome prediction is necessary for successful treatment allocation. Using pathobiological variables (available in mostclinical records: tumor size, nodal involvement, estrogen and progesterone receptor content) from 596 patients recruitedat a comprehensive cancer center, we developed a prediction model which we validated in an independent cohort of 175patients recruited at a general hospital. Calculated at 3 and 4 years of follow-up, the discrimination indices were 0.716[confidence limits (CL) 0.641, 0.752] and 0.714 (CL 0.650, 0.750) for the training data, and 0.726 (CL 0.591, 0.769) and0.677 (CL 0.580, 0.745) for the testing data. Waiting for more effective approaches from genomic and proteomic studies, amodel based on consolidated pathobiological variables routinely assessed at relatively low costs may be considered as thereference for assessing the gain of new markers over traditional ones, thus substantially improving the conventional use ofprognostic criteria.

A novel retinoic/butyric hyaluronan ester for the treatment of acute promyelocytic leukemia: preliminary preclinical results.

All-trans retinoic acid (ATRA) represents the therapy of choice for patients with acute promyelocytic leukemia (APL). However, patients often relapse due to ATRA-resistance. The molecular basis of APL alterations indicates that addition of a histone deacetylase inhibitor to ATRA may restore the sensitivity to retinoids. We explored the in vitro and in vivo effects of a novel retinoic/butyric hyaluronan ester (HBR) on a retinoic acid (RA)-sensitive human myeloid cell line, NB4, and on its RA-resistant subclone, NB4.007/6. In vitro, HBR induced growth arrest and terminal differentiation in RA-sensitive NB4 cells (as confirmed by an increased expression of CD11 family members and nitroblue tetrazolium assay), whereas it inhibited the growth of RA-resistant cells by apoptosis, paralleled by an increase in the levels of caspase 3 and 7. In vivo, HBR treatment of NB4-inoculated severe combined immunodeficient mice resulted in a statistically significant increase in survival time (P<0.0001), comparable to that induced by a maximum tolerated dose of RA alone. Also on P388-inoculated mice, HBR was active in contrast to RA that was completely ineffective. Present findings suggest that, owing to the simultaneous presence of RA and an histone deacetylases inhibitor, HBR might be useful in controlling the proliferation of RA-resistant cells and the differentiation of RA-sensitive cells.

Comparison of immunochemical and radioligand binding assays for estrogen receptors in human breast tumors.

We have compared a new enzyme immunoassay (EIA) for estrogen receptors (ER) with our conventional radioligand binding assays (multipoint dextran-coated charcoal assay for cytoplasmic ER and hydroxylapatite exchange assay for nuclear ER). Cytoplasmic ERs were measured in 76 human breast cancer specimens by EIA and by five-point Scatchard analysis. The correlation between the two assays yielded a straight line with a slope of 0.92 (r = 0.95; P less than 0.001); conversely, in 31 nuclear salt extracts, linear regression analysis of hydroxylapatite exchange assay data with EIA showed a clear correlation (r = 0.93; P less than 0.001) but a slope of 1.7, demonstrating that EIA detects more ER sites. The binding of the antibody to the cytoplasmic ER molecules was investigated by sucrose density gradient analysis, which showed that EIA recognizes both cytoplasmic forms (9 and 3S), but does not distinguish between them. Advantages and drawbacks of this method are discussed with respect to its application for routine receptor determination for clinical management of breast cancer patients.

Time-dependent relevance of steroid receptors in breast cancer.

PURPOSE: To analyze the time-dependent prognostic role of the investigated variables, considered, when appropriate, on a continuous scale, for the purpose of evaluating and describing the interrelationships between clinically relevant patient and tumor characteristics (age, size and histology, and estrogen receptor [ER] and progesterone receptor content) and the risk of new disease manifestation. PATIENTS AND METHODS: We applied a flexible statistical model to a case series of 1,793 patients with axillary lymph node-negative breast cancer with a minimal potential follow-up of 10 years. To avoid a potential confounding effect of adjuvant treatment, only patients given local-regional therapy until relapse were considered. RESULTS: ER content and tumor size (adjusted for all the other covariates) showed a time-dependent relationship with the risk of new disease manifestations. In particular, ER content failed to show a prognostic effect within the first years of follow-up; thereafter, a positive association with risk of relapse was observed. For tumor size, within the first years of follow-up, the risk of relapse was directly related to size for only tumors up to 2.5 cm in diameter; thereafter, the impact on prognosis progressively decreased. CONCLUSION: The availability of a long follow-up on a large breast cancer series, as well as the use of innovative statistical approaches, allowed us to explore the functional relation between steroid receptors and clinical outcome and to generate a hypothesis on the involvement of ER in favoring long-term metastasis development.

Cell kinetics as a predictive factor in node-positive breast cancer treated with adjuvant hormone therapy.

PURPOSE: The fraction of cells that incorporate 3H-thymidine (3H-dT labeling index [3H-dT LI]) proved to be a prognostic indicator in patients with node-negative and node-positive resectable breast cancers treated with locoregional treatment alone or with adjuvant combination chemotherapy. In this study, we assessed the prognostic role of 3H-dT LI alone and in association with other pathologic and biologic variables in a series of 249 women with node-positive breast cancers treated with adjuvant endocrine therapy. PATIENTS AND METHODS: All patients were postmenopausal, had resectable estrogen receptor-positive (ER+) tumors, and had received tamoxifen for at least 1 year after radical or conservative surgery plus radiotherapy. The median follow-up duration was 48 months. RESULTS: The 4-year relapse-free survival (RFS) rates were significantly lower for patients with large tumors (> 2 cm), with more than three positive lymph nodes, with low (< 150 fmol/mg proteins) ER content, without progesterone receptors (PgRs), or with rapidly proliferating tumors. 3H-dT LI provided prognostic information independent of axillary node involvement, ER content, PgR status, and tumor size, with an estimated odds ratio (OR) higher than that of tumor size, lymph node involvement, or ER concentration. In addition, 3H-dT LI and PgR in association were able to identify patients with different risks of relapse within subsets of tumors with less or more than three positive nodes. CONCLUSION: 3H-dT LI provides prognostic information complementary to PgR, tumor size, lymph node involvement, and ER content in the prediction of RFS of postmenopausal patients with node-positive, ER + resectable tumors treated with adjuvant hormone therapy.

Adjuvant CMF for node-negative and estrogen receptor-negative breast cancer patients.

From December 1980 to September 1985, a total of 90 eligible patients with stage T1-3a, node-negative, and estrogen receptor-negative (less than or equal to 10 fmol/mg of cytosol protein) tumors were entered into a randomized study to assess the effectiveness of adjuvant intravenous (IV) cyclophosphamide, methotrexate, and fluorouracil (CMF) in a subset of patients at high risk of early disease relapse. High values of [3H]thymidine labeling index were documented in two thirds of 62 assessed specimens from the patient population, and one half of the patients had histologically undifferentiated tumors. Patients were allocated to either local-regional modality alone (control group, 45 women) or to CMF (45 patients) after surgery. A full dose of CMF (600 mg/m2 each of cyclophosphamide and fluorouracil, and 40 mg/m2 of methotrexate) was administered IV on day 1, and then repeated every 3 weeks for a total of 12 treatments. After a median follow-up of 80 months, the 7-year results confirmed the superiority of adjuvant CMF compared to local-regional modality alone (relapse-free survival 85% vs 42%, P = .0001; total survival 86% vs 58%, P = .006). A benefit from adjuvant CMF was observed in all subgroups, and the rates of both local-regional and distant failure were decreased. Treatment was fairly well tolerated and devoid of life-threatening toxicity. Present results confirm our previous observation concerning the dismal prognosis of node-negative and estrogen receptor-negative breast cancer patients as well as the beneficial effect of adjuvant chemotherapy in this selected subset.

Sodium butyrate modulates cell cycle-related proteins in HT29 human colonic adenocarcinoma cells.

Sodium butyrate (NaB), a product of colonic fermentation of dietary fibre, has been shown to inhibit cell proliferation by blocking cells in the G0/G1 phase of the cell cycle through a mechanism of action still not completely understood. We investigated the effect of NaB on the level of some G1 phase-related proteins in a colon carcinoma cell line (HT29). In particular, we addressed our attention to cyclin D1 (the key regulator of G1S progression), p21waf1/cip1 (the main inactivator of the cyclin D/cdk complex), and p53 (the most important regulator of p21waf1/cip1 gene transcription). At inhibitory concentrations (higher than 1 mM) NaB reduced cyclin D1 and p53 level in a dose-dependent manner and sustained the synthesis of p21waf1/cip1, probably in a p53-independent way, accounting for the G0/G1 block observed by flow cytometry. Present results provide further evidence on the molecular mechanism at the basis of the physiological role of NaB and support the hypothesis that an unbalanced diet, poor in carbohydrates and therefore in NaB, could result in functional alterations with clinical and carcinogenic implications.

Effect of sodium butyrate on human breast cancer cell lines.

We have investigated the effects exerted by sodium butyrate (NaBu) on the growth and cell cycle perturbations of four human breast cancer cell lines (MCF7, T47D, MDA-MB231 and BT20) with different steroid receptor profiles. Moreover, since one of the supposed mechanisms of action for NaBu activity involves the induction of apoptosis, we have studied the effects of NaBu on DNA fragmentation by agarose gel electrophoresis and flow cytometry. In all investigated cell lines, NaBu exerted a time- and dose-dependent inhibition of growth and caused a maximum inhibitory effect (85% to 90%) at the concentration of 2.5 mM. The inhibition was already evident after 3 days of treatment. The antiproliferative effect of NaBu was associated with a persistent block of cells in the G2M phase. The block was associated with apoptosis only in oestrogen-receptor positive cell lines. The inhibiting effect of NaBu in hormone-dependent and independent cell lines and its ability to induce apoptosis through a cell cycle perturbation in hormone-dependent cell lines may have important implications in the treatment of human tumours including breast cancer.

Prognostic relevance of cathepsin D versus oestrogen receptors in node negative breast cancers.

The concentration of total cathepsin D in cytosols of 199 node negative women with primary breast cancer in a 10-year retrospective cohort was assayed. Cathepsin D status alone was unable to predict disease-free or overall survival. However, those patients with receptor positive tumours who were cathepsin D positive had shorter [corrected] disease-free (P = 0.02) and overall survival (P = 0.01) than cathepsin D negative patients. Therefore, measurement of cathepsin D appears to provide additional prognostic information for the prediction of disease-free and overall survival in patients with node negative breast cancer.

Interaction between hormone-dependent and hormone-independent human breast cancer cells.

We developed two different models based on in vitro co-culture of hormone-dependent and hormone-independent cell lines to simulate the cell population heterogeneity of human breast cancer tumours. Oestrogen-dependent (MCF-7, ZR 75.1) and oestrogen-independent cell lines (MDAMB-231 BT-20) were grown under serum-free conditions. Co-culture of hormone-dependent and hormone-independent cell lines resulted in an increased cell yield compared to single cell cultures carried out at the same seeding ratios. Such an increase was not affected by addition of oestradiol and single growth factors (EGF, bFGF and IGF-I). These results allow us to conclude that in a heterogeneous cell population like human breast tumours, interaction between hormone-dependent and hormone-independent cell lines may result in a complex regulation of cell growth.

Prognostic relevance of pS2 status in association with steroid receptor status and proliferative activity in node-negative breast cancer.

Expression of the oestrogen-regulated pS2 protein was investigated on paraffin-embedded sections of primary breast tumours from 200 node-negative patients. Immunoreactivity was observed in 56% of the cases. pS2 expression was inversely correlated with tumour size and proliferative activity, whereas a direct correlation was observed with steroid receptor. 5-year relapse free survival was influenced by tumour size (P = 0.02), oestrogen receptor status (P less than 0.05), and proliferative activity (P less than 0.01). No difference in relapse-free survival was observed between patients subdivided according to pS2 expression alone. However, among patients with oestrogen-receptor-negative tumors, pS2 expression predicted a shorter relapse-free survival.

Biological characterisation of primary and metachronous lesions in breast cancer patients.

Proliferative activity, evaluated as [3H]thymidine labelling index ([3H]dT LI), and hormone receptors were determined on 97 primary breast cancers and on metachronous lesions from the same patient. Overall, the [3H]dT LI of metachronous lesions was significantly higher than that of the primary tumour (P = 0.003). Hormone receptor profiles of the two lesions were similar in about 75% of the cases; disagreements were mainly due to a disappearance of hormone receptors in metachronous lesions. In contralateral tumours, [3H]dT LI and hormone receptors were unrelated to those of the relative primary lesion. In this series of relapsing patients, [3H]dT LI was unrelated to hormone receptor status in the primary tumour, but it was higher in the metachronous lesions from patients with hormone receptor-negative primary tumours. For patients given no systemic therapy between surgery and relapse, the time to develop local-regional recurrences or contralateral tumours was inversely related to the [3H]dT LI of the metachronous lesions.

Is steroid receptor profile in contralateral breast cancer a marker of independence of the corresponding primary tumour?

We compared oestrogen receptor (ER) and progesterone receptor (PgR) profiles between primary and corresponding contralateral breast cancer (CBC) to investigate whether CBC should be considered relapse of a primary or as a feature of the multicentric origin of breast cancer. We adjusted for patient age, menopausal status, histology and adjuvant therapy. In spite of the general application of a cut-off value to dichotomise ER and PgR, we considered them as continuous variables. Moreover, we considered as synchronous cancers only simultaneously occurring lesions. For 399 patients, ER and PgR receptor levels in primary and CBC did not differ significantly, but were significantly correlated within the same patient. The correlation was higher for synchronous than for metachronous lesions when considering ER, but not PgR. The correlation between ER and PgR levels in the same tumour (primary or CBC) appeared stronger than the correlation of either receptor type (ER or PgR) between primary and CBC. Age, histology and adjuvant treatment affected ER concentration, whereas age, menopausal status and histology affected PgR concentration. The analysis indicated that primary and CBC tend to be characterised by a similar steroid receptor profile. The finding may support the hypothesis of CBC as a second primary arising in a common predisposing milieu, rather than a primary-dependent contralateral lesion. In this light, the clinical management of patients with a bilateral breast cancer should be similar to that of a unilateral breast cancer.

Growth stimulatory effect and metabolism of testosterone in MCF-7 human breast cancer cells.

The purpose of our study was to evaluate the effect of testosterone and its metabolic pathway in MCF-7 cells in culture. Testosterone exhibited a dose-dependent (from 0.1 to 10 nM) and time-dependent (from 3 to 9 days) growth stimulation. The metabolic pathway was investigated following treatment with two testosterone concentrations: one stimulating (10 nM) and one not affecting (0.1 nM) cell growth. Celite column chromatography was used to separate H-3-testosterone metabolites, whose identity was confirmed by gas chromatography-mass spectrometry analysis. The main findings of the metabolic study were: i) recovery of a large amount of untransformed testosterone; ii) a high conversion of testosterone to conjugated, biologically inactive metabolites; iii) the highest level of Sa-diol among the metabolites of testosterone; iv) a conversion (2%) of testosterone into oestradiol, which resulted in a growth stimulatory concentration when testosterone was used at 10 nM. We conclude that in our experimental conditions androgens and oestrogens can concur to stimulate MCF-7 cell growth through androgen receptor-mediated and oestrogen receptor-mediated mechanisms.

Receptor status variation in primary breast cancer and subsequent accessible relapse.

To better understand the prognostic relevance of change in steroid receptor status, during the clinical course of breast cancer, we analysed the variation of estrogen and progesterone receptor (ER, PgR) status in a series of 532 primary tumors and metachronous accessible recurrences in individual patients. A more consistent variation was observed in patients with a receptor-positive primary (ER(+) or PgR(+)) than in those with a receptor-negative tumor (ER(-) or PgR(-)). Forty-four percent of PgR(+) and 24% of ER(+) tumors became negative, whereas only 20% of ER(-) or PgR(-) became positive. The changes were independent of tumor stage and menopausal status. However, steroid receptor variation appeared to be related to the interval between the primary tumor and relapse. In fact, the changes from ER(+) to ER(-) were more frequent in patients with a disease-free survival of less than 1 year, whereas changes from ER(-) to ER(+) occurred more often in patients with a disease-free survival of more than 3 years. Moreover, we observed a decrease in the number of ER(+) tumors following hormone treatment and a decrease in ER(-) tumors following chemotherapy. However, such variations did not reach statistical significance. Irrespective of the type of adjuvant therapy, the presence of at least one receptor (in particular, PgR) in the metachronous lesion was correlated with a long median time to relapse and to death. Our results confirmed the predictive relevance of receptor status of the primary lesion on relapse and survival and suggest the predictive relevance of receptor status of the metachronous lesion on post-relapse survival.

Influence of culture conditions on the estrogenic cell growth stimulation of human breast cancer cells.

17 beta-Estradiol is a potent mitogen for hormone-dependent cell lines (MCF-7, T47D and ZR 75.1). However, the degree of hormone sensitivity is very much influenced by culture conditions. In order to understand which factors modulate estrogenic effects on cell growth, four different culture conditions were used: (a) medium with dextran-coated charcoal-treated fetal calf serum (DCC-FCS); (b) medium with dextran-coated charcoal-treated growth factor-inactivated serum (DCC-FCSd); (c) serum-free medium, after a 24-h incubation with serum to allow cell attachment; and (d) serum-free medium on collagen IV-treated plates. In all cell lines the highest cell growth stimulation was achieved when estradiol was added in the presence of 5% DCC-FCS, whereas reducing or removing serum from the culture medium resulted in a decrease in cell proliferation stimulation. We postulate that serum contains some still unknown components able to modulate the degree of estrogenic action in endocrine-dependent breast cancer cell lines.

Tamoxifen and beta-interferon: effect of simultaneous or sequential treatment on breast cancer cell lines.

The presence of steroid receptors in breast cancer is usually considered as a good indicator for responsiveness to antiestrogen treatment. However, not all estrogen-receptor (ER) positive tumors respond to tamoxifen, probably owing to the natural heterogeneity of breast cancer, which after tamoxifen treatment can result in an overgrowth of selected ER-negative clones. Since in a previous study we found that beta-interferon exerts an antiproliferative activity on several breast cancer cell lines, regardless of their steroid receptor status, we addressed our attention to the possibility of improving tamoifen efficacy by the addition of beta-interferon. Thus, we investigated the effect of concomitant or sequential treatment with tamoxifen and beta-interferon on breast cancer cell lines (MCF7, T47D, MDA-MB231, BT20) characterized by a different steroid receptor status. The results showed that beta-interferon caused a cell growth inhibition additional to that produced by tamoxifen, regardless of the receptor status of the cell lines. These findings indicate the potential of the combined treatment with tamoxifen and beta-interferon due to the direct effect of beta-interferon on ER-negative cells and the potentiation of tamoxifen activity in ER-positive cells, perhaps through the induction of steroid receptor synthesis.

Activity of tamoxifen and new antiestrogens on estrogen receptor positive and negative breast cancer cells.

The effect of some new antiestrogens (ICI 164384, ICI 182780, Ly 133314 and Ly 117018) on the growth of a panel of breast cancer cell lines (MDA-MB 231, BT20, MCF7 and T47D) was studied. Their antiestrogenic activity was investigated in the presence of a physiologic concentration of estradiol and compared with the effect displayed by tamoxifen in the same experimental conditions. Tamoxifen confirmed its antagonistic activity in the presence of estradiol, whereas when given alone it did not exhibit a clear antiproliferative effect. All other compounds showed variable activity: ICI 164384 and ICI 182780 exerted a variable inhibitory effect in all cell lines, but only in the absence of estradiol; Ly 133314 and Ly 117018 did not show a clear antagonistic activity and sometimes had a synergistic effect with estradiol in increasing cell growth. These results indicate an extreme variability in terms of antagonistic effect of these new compounds and suggest their inadequacy to replace tamoxifen as an antiestrogen during endocrine treatment. Interestingly, ICI 164384 exerted an antiproliferative action also an estrogen receptor-negative cell lines, probably through an alternative mechanism non estrogen receptor-mediated, supporting the hypothesis that it could be effective on estrogen receptor-positive as well as estrogen receptor-negative tumors.