Tamoxifen reduces serum insulin-like growth factor I (IGF-I)

The Value of ER∝ in the Prognosis of GH- and PRL-Secreting PitNETs: Clinicopathological Correlations

Pituitary neuroendocrine tumors (PitNETs) are divided into multiple histological subtypes, which determine their clinical and biological variable behavior. Despite their benign evolution, in some cases, prolactin (PRL) and growth hormone (GH)-secreting PitNETs may have aggressive behavior. In this study, we investigated the potential predictive role of ER∝, alongside the clinicopathological classification of PitNETs (tumor diameter, tumor type, and tumor grade). A retrospective study was conducted with 32 consecutive cases of PRL- and mixed GH- and PRL-secreting PitNETs (5 patients with prolactinomas and 27 with acromegaly, among them, 7 patients with GH- and PRL- co-secretion) who underwent transsphenoidal intervention. Tumor specimens were histologically and immunohistochemical examined: anterior pituitary hormones, ki-67 labeling index, CAM 5.2, and ER∝; ER∝ expression was correlated with basal PRL levels at diagnosis (rho = 0.60, p < 0.01) and postoperative PRL levels (rho = 0.58, p < 0.001). In our study, the ER∝ intensity score was lower in female patients. Postoperative maximal tumor diameter correlated with Knosp grade (p = 0.02); CAM 5.2 pattern (densely/sparsely granulated/mixed densely and sparsely granulated) was correlated with postoperative PRL level (p = 0.002), and with ki-67 (p < 0.001). The IGF1 level at diagnosis was correlated with the postoperative GH nadir value in the oral glucose tolerance test (OGTT) (rho = 0.52, p < 0.05). Also, basal PRL level at diagnosis was correlated with postoperative tumor diameter (p = 0.63, p < 0.001). At univariate logistic regression, GH nadir in OGTT test at diagnostic, IGF1, gender, and invasion were independent predictors of remission for mixed GH- and PRL-secreting Pit-NETs; ER∝ can be used as a prognostic marker and loss of ER∝ expression should be considered a sign of lower differentiation and a likely indicator of poor prognosis. A sex-related difference can be considered in the evolution and prognosis of these tumors, but further studies are needed to confirm this hypothesis.

Nutritional Status Predicts Fatty Acid Uptake from Fish and Soybean Oil Supplements for Treatment of Cancer-Related Fatigue: Results from a Phase II Nationwide Study

Cancer-related fatigue is a prevalent and debilitating condition that persists for years into survivorship. Studies evaluating both fish oil supplementation on fatigue and associations between fish oil consumption and fatigue have shown mixed effects; it is unknown what factors contribute to these differential effects. Herein, we investigate whether the nutritional status of cancer survivors was associated with serum omega-3 concentration or change in serum omega-3s throughout a fish oil supplementation study, and then if any of these factors were associated with fatigue. Breast cancer survivors 4-36 months post-treatment with moderate-severe fatigue were randomized to take 6 g fish oil, 6 g soybean oil, or 3 g of each daily for 6 weeks. Baseline nutritional status was calculated using the Controlling Nutritional Status tool (serum albumin, lymphocytes, cholesterol). At baseline and post-intervention, serum fatty acids were quantified and fatigue was assessed using the Multidimensional Fatigue Symptom Inventory. Participants (n = 85) were 61.2 ± 9.7 years old with a body mass index of 31.9 ± 6.7 kg/m²; 69% had a good nutritional score and 31% had light-moderate malnutrition. Those with good nutritional status had greater total serum omega-3s at baseline (p = 0.013) and a greater increase in serum omega-3s with supplementation (p = 0.003). Among those who were supplemented with fish oil, greater increases in serum omega-3s were associated with greater improvements in fatigue. In conclusion, good nutritional status may increase uptake of fatty acid supplements, increasing their ability to improve fatigue.

The significance of estrogen receptors in acromegaly: Are they useful as predictors of prognosis and therapy regimen?

OBJECTIVE

In this study, we considered to assess the presence of estrogen receptors (ER) and the expression of estrogen receptor genes (ESR) in the surgical tissue samples of acromegaly patients and the control group patients with nonfunctioning adenoma and their association with disease activity. We also aimed to determine the significance of ER positivity in acromegaly patients and to find out whether it carries a potential to be used as a predictor of prognosis and therapy regimen in the future.

DESIGN

This study was conducted on a total of 67 patients over 18 years of age. The study group consisted of 34 patients with acromegaly and 33 patients with nonfunctioning pituitary adenoma. The pre- and post-operative basal pituitary hormone levels and magnetic resonance images (MRI) of all patients, as well as their remission status of all acromegaly patients were evaluated. Immunohistochemical (IHC) staining procedures for ER-α were performed on surgical tissue samples. Real-time quantitative polymerase chain reaction (RT-qPCR) method was used to determine the levels of ESR1 and ESR2 gene expressions.

RESULTS

We found that IHC staining for ER-α was positive in 31.3% and 45.5% of the patients with acromegaly and nonfunctioning adenoma respectively. There was no statistically significant difference of ER-α positivity, ER-α immunoreactivity score and ESR1/ESR2 gene expression levels among the study groups (p > .05). Nevertheless, the expression of ESR1 gene was found to be 0.26 times more, and the ESR2 gene to be 0.11 times less in the acromegaly group compared to those of the nonfunctioning adenoma group. Additionally, we detected the positivity of ER-α only in acromegaly patients who were in remission. An inverse association was found between the pre-operative insulin-like growth factor-1 (IGF-1) levels and the expressions of ESR1/ESR2 gene in acromegaly patients. So these results indicated that the high ESR1 and ESR2 gene expressions in acromegaly patients are associated to the decrease of pre-operative IGF-1 values. Also an inverse association was found between the pre-operative adenoma volume and ESR1 Ct values, means that increase in ESR1 gene expression is associated to the decrease of adenoma volume.

CONCLUSIONS

The current results may suggest the use of these parameters as useful prognostic markers because all ER-positive acromegaly patients were in remission and the high ESR1 and ESR2 gene expressions in acromegaly patients is associated to the decrease of pre-operative IGF-1 values. Our results need to be supported by further studies.

Mammographic density: a potential monitoring biomarker for adjuvant and preventative breast cancer endocrine therapies

Increased mammographic density (MD) has been shown beyond doubt to be a marker for increased breast cancer risk, though the underpinning pathobiology is yet to be fully elucidated. Estrogenic activity exerts a strong influence over MD, which consequently has been observed to change predictably in response to tamoxifen anti-estrogen therapy, although results for other selective estrogen receptor modulators and aromatase inhibitors are less consistent. In both primary and secondary prevention settings, tamoxifen-associated MD changes correlate with successful modulation of risk or outcome, particularly among pre-menopausal women; an observation that supports the potential use of MD change as a surrogate marker where short-term MD changes reflect longer-term anti-estrogen efficacy. Here we summarize endocrine therapy-induced MD changes and attendant outcomes and discuss both the need for outcome surrogates in such therapy, as well as make a case for MD as such a monitoring marker. We then discuss the process and steps required to validate and introduce MD into practice as a predictor or surrogate for endocrine therapy efficacy in preventive and adjuvant breast cancer treatment settings.

Qualitative Versus Quantitative Mammographic Breast Density Assessment: Applications for the US and Abroad

Mammographic breast density (MBD) has been proven to be an important risk factor for breast cancer and an important determinant of mammographic screening performance. The measurement of density has changed dramatically since its inception. Initial qualitative measurement methods have been found to have limited consistency between readers, and in regards to breast cancer risk. Following the introduction of full-field digital mammography, more sophisticated measurement methodology is now possible. Automated computer-based density measurements can provide consistent, reproducible, and objective results. In this review paper, we describe various methods currently available to assess MBD, and provide a discussion on the clinical utility of such methods for breast cancer screening.

Estrogens and selective estrogen receptor modulators in acromegaly

Despite recent advances in acromegaly treatment by surgery, drugs, and radiotherapy, hormonal control is still not achieved by some patients. The impairment of IGF-1 generation by estrogens in growth hormone deficient patients is well known. Patients on oral estrogens need higher growth hormone doses in order to achieve normal IGF-1 values. In the past, estrogens were one of the first drugs used to treat acromegaly. Nevertheless, due to the high doses used and the obvious side effects in male patients, this strategy was sidelined with the development of more specific drugs, as somatostatin receptor ligands and dopamine agonists. In the last 15 years, the antagonist of growth hormone receptor became available, making possible IGF-1 control of the majority of patients on this particular drug. However, due to its high cost, pegvisomant is still not available in many centers around the world. In this setting, the effect of estrogens and also of selective estrogen receptor modulators on IGF-1 control was reviewed, and proved to be an ancillary tool in the management of acromegaly. This review describes data concerning their efficacy and place in the treatment algorithm of acromegaly.

PCOS and cancer risk

Polycystic ovary syndrome (PCOS) affects approximately 5 to 10% of women of reproductive age. It is the most common reason of anovulation in infertile women. PCOS is accompanied by such conditions as oligo- or anovulation, hipertestosteronism, lower cell sensitivity to insulin, type II diabetes, hyperlipidemia and obesity. Each of the above-mentioned conditions is an approved risk factor proved to predispose towards cancer. However, PCOS is also a disease entity which differs in its clinical manifestation. For example not all patients suffer from obesity or hipertestosteronism related symptoms. From the analysis of literature it is possible to draw conclusions, that there is a possible correlation between PCOS and endometrial cancer, which emerges from clinical trials or research focused on molecular changes in endometrium patients with PCOS. On the other hand, correlation between PCOS and breast or ovary cancer is not so strong, in spite of single papers which are showing the link. The main problem in researching the correlation between PCOS and any cancer risk, is there is a very small group of women or the trial is imperfect (e.g. no control group). There is no meta-analysis focused on this correlation in literature. The change of criteria of PCOS in the past is also a big problem, because there was a number of definitions of PCOS, which results in inconsistent PCOS diagnoses over time. In this paper we would like to provide a description of studies that aimed at showing correlation between PCOS and cancer risk and underlying theoretical assumptions.

Tamoxifen prevents apoptosis and follicle loss from cyclophosphamide in cultured rat ovaries

Recent studies documented that the selective estrogen receptor modulator tamoxifen prevents follicle loss and promotes fertility following in vivo exposure of rodents to irradiation or ovotoxic cancer drugs, cyclophosphamide and doxorubicin. In an effort to characterize the ovarian-sparing mechanisms of tamoxifen in preantral follicle classes, cultured neonatal rat ovaries (Day 4, Sprague Dawley) were treated for 1-7 days with active metabolites of cyclophosphamide (i.e., 4-hydroxycyclophosphamide; CTX) (0, 1, and 10 μM) and tamoxifen (i.e., 4-hydroxytamoxifen; TAM) (0 and 10 μM) in vitro, and both apoptosis and follicle numbers were measured. CTX caused marked follicular apoptosis and follicular loss. TAM treatment decreased follicular loss and apoptosis from CTX in vitro. TAM alone had no effect on these parameters. IGF-1 and IGF-1 receptor were assessed in ovarian tissue showing no impact of TAM or CTX on these endpoints. Targeted mRNA analysis during follicular rescue by TAM revealed decreased expression of multiple genes related to inflammation, including mediators of lipoxygenase and prostaglandin production and signaling (Alox5, Pla2g1b, Ptgfr), cytokine binding (Il1r1, Il2rg ), apoptosis (Tnfrsf1a), second messenger signaling (Mapk1, Mapk14, Plcg1), as well as tissue remodeling and vasodilation (Bdkrb2, Klk15). The results suggest that TAM protects the ovary from CTX-mediated toxicity through direct ovarian actions that oppose follicular loss.

Insights into the protective mechanisms of tamoxifen in radiotherapy-induced ovarian follicular loss: impact on insulin-like growth factor 1

Radiotherapy is one of the most common and effective cancer treatments. However, it has a profound impact on ovarian function, leading to premature ovarian failure. With the hope of preserving fertility in cancer survivors, the need for an effective radioprotective therapy is evident. The present study investigated the mechanism of the potential radioprotective effect of tamoxifen (TAM) on γ-irradiation-induced ovarian failure on experimental rats and the impact of the IGF-1 in the underlying protective mechanisms. Female Sprague Dawley rats were either exposed to single whole-body irradiation (3.2 Gy; lethal dose [LD₂₀]) and/or treated with TAM (1 mg/kg). γ-Irradiation caused an array of ovarian dysfunction that was evident by assessment of hormonal changes, follicular development, proliferation marker (proliferating cell nuclear antigen), and oxidative stress as well as apoptotic markers. In addition, IGF-1/IGF-1 receptor axis expression was assessed using real-time RT-PCR and immunolocalization techniques. Furthermore, fertility assessment was performed. TAM significantly enhanced follicular development and restored the anti-Mullerian hormone level. Moreover, it ameliorated the deleterious effects of irradiation on oxidative stress, proliferating cell nuclear antigen expression, and apoptosis. Interestingly, TAM was shown to enhance the ovarian IGF-1 but not IGF-1 receptor, a property that contributed significantly to its radioprotective mechanisms. Finally, TAM regained the fertility that was lost after irradiation. In conclusion, TAM showed a radioprotective effect and saved the ovarian reserve and fertility through increasing anti-Mullerian hormone and the local IGF-1 level and counteracting the oxidative stress-mediated apoptosis.

Associations of insulin-like growth factor and insulin-like growth factor binding protein-3 with mortality in women with breast cancer

Elevated circulating insulin-like growth factor-1 (IGF-1), a breast epithelial cell mitogen, is associated with breast cancer development. However, its association with breast cancer survival is not established. Circulating concentrations of IGF-1 are controlled via binding proteins, including IGF Binding Protein-3 (IGFBP-3), that may modulate the association of IGF-1 with breast-cancer outcomes. We measured IGF-1 and IGFBP-3 concentrations in serum from 600 women enrolled in the health, eating, activity, and lifestyle (HEAL) study, a multiethnic, prospective cohort study of women diagnosed with stage I-IIIA breast cancer. We evaluated the association between IGF-1 and IGFBP-3, and as a ratio, modeled using quintile cut-points, with risk of breast cancer-specific (n = 42 deaths) and all-cause mortality (n = 87 deaths) using Cox proportional hazards models. In models adjusted for body mass index, ethnicity, tamoxifen use at time of blood draw, treatment received at diagnosis and IGFBP-3, women in the highest quintile of IGF-1 level had an increased risk of all-cause mortality (Hazard Ratio (HR) = 3.10, 95% CI 1.21-7.93, p = 0.02), although no dose-response association was evident. The IGF-1/IGFBP-3 ratio, an indicator of free IGF-I levels, was significantly associated with increasing risk of all-cause mortality (HR = 2.83, 95% CI 1.25-6.36 p(trend) = 0.01, upper vs. lower quintile) in a fully adjusted model. In conclusion, high serum levels of IGF-1 and the IGF-1/IGFBP-3 ratio were associated with increased risk of all-cause mortality in women with breast cancer. These results need to be confirmed in larger breast cancer survivor cohorts.

Insulin-like growth factor-1, insulin-like growth factor-binding protein-3, growth hormone, and mammographic density in the Nurses' Health Studies

Higher circulating insulin-like growth factor I (IGF-1) levels have been associated with higher mammographic density among women in some, but not all studies. Also, few studies have examined the association between mammographic density and circulating growth hormone (GH) in premenopausal women. We conducted a cross-sectional study among 783 premenopausal women and 436 postmenopausal women who were controls in breast cancer case-control studies nested in the Nurses' Health Study (NHS) and NHSII. Participants provided blood samples in 1989-1990 (NHS) or in 1996-1999 (NHSII), and mammograms were obtained near the time of blood draw. Generalized linear models were used to assess the associations of IGF-1, IGF-binding protein-3 (IGFBP-3), IGF-1:IGFBP-3 ratio, and GH with percent mammographic density, total dense area, and total non-dense area. Models were adjusted for potential confounders including age and body mass index (BMI), among others. We also assessed whether the associations varied by age or BMI. In both pre- and postmenopausal women, percent mammographic density was not associated with plasma levels of IGF-1, IGFBP-3, or the IGF-1:IGFBP-3 ratio. In addition, GH was not associated with percent density among premenopausal women in the NHSII. Similarly, total dense area and non-dense area were not significantly associated with any of these analytes. In postmenopausal women, IGF-1 was associated with higher percent mammographic density among women with BMI <25 kg/m(2), but not among overweight/obese women. Overall, plasma IGF-1, IGFBP-3, and GH levels were not associated with mammographic density in a sample of premenopausal and postmenopausal women.

Hormonal mechanisms underlying the relationship between obesity and breast cancer

Given the worldwide epidemic of obesity, it is inevitably an increasingly common comorbidity for women who develop breast cancer; therefore, it is critical to understand its impact on this disease. This review focuses on the influence of obesity on breast cancer development and progression and describes the hormonal factors that may underlie the observations, with particular emphasis on the roles of estrogen, insulin/insulin-like growth factor axis, and adipokines.

IGF binding proteins (IGFBPs) and regulation of breast cancer biology

The IGFBP family comprises six proteins with high affinity for the IGFs. Changes in the balance of the components of the IGF system may contribute to the progression of breast cancer. In tumours the abundance of IGFBPs relates to the estrogen receptor status and their production in the breast is controlled by hormones, principally estrogen and progesterone. Important interactions occur between IGFBPs and key growth regulators such as TGF-beta, PTEN and EGF which are reviewed. The conflicting observations between the effects of IGFBPs on the risk of breast cancer, in particular IGFBP-3, obtained from epidemiology studies in comparison to in vivo observations are highlighted and potential explanations provided. The functional activity of IGFBPs can also be affected by proteolysis, phosphorylation and glycosylation and the implications of these are described. The IGFs are generally present at levels far in excess of that required for maximal receptor stimulation, and the IGFBPs are critical regulators of their cellular actions. IGFBPs can affect cell function in an IGF-dependent or independent manner. The key mechanisms underlying the intrinsic actions of the IGFBPs are still in debate. IGF bioactivity locally in the breast is influenced not only by local tissue expression and regulation of IGFs, IGFBPs and IGFBP proteases, but also by these factors delivered from the circulation. Finally, the therapeutic potential of IGFBPs-2 and -3 are considered together with key questions that still need to be addressed.

Use of biomarkers for breast cancer risk assessment and prevention

Epidemiologic models used for cancer risk prediction, such as the Gail model, are validated for populations undergoing regular screening but often have suboptimal individual predictive accuracy. Risk biomarkers may be employed to improve predictive accuracy based on the Gail or other epidemiologic models and, to the extent that they are reversible, may be used to assess response in phase I-II prevention trials. Risk biomarkers used as intermediate response endpoints include high mammographic breast density, intra-epithelial neoplasia, and cytomorphology with associated molecular markers such as Ki-67. At the present time these biomarkers may not be used to predict or monitor individual response to standard prevention interventions but are used in early phase clinical trials as preliminary indicators of efficacy.

Regulation of growth hormone signaling by selective estrogen receptor modulators occurs through suppression of protein tyrosine phosphatases

Activation of the Janus kinase 2 (JAK2)/signal transducer and activator of transcription 5 (STAT5) pathway by GH is terminated by the suppressors of cytokine signaling (SOCSs) and protein tyrosine phosphatases, Src homology 2 domain-containing protein tyrosine phosphatase (SHP)-1 and SHP-2. Based on our recent report that estrogen inhibits GH signaling by stimulating SOCS-2 expression, we investigated the effects of selective estrogen receptor modulators (SERMs) on GH signaling in human embryonic kidney (HEK293) and breast cancer (MDA-MB-231) cells expressing human GH receptor and estrogen receptor-alpha. 17beta-estradiol (E(2)) suppressed GH activation of a STAT5-responsive luciferase reporter and JAK2 phosphorylation in both cell models. 4-hydroxytamoxifen and raloxifene augmented these actions of GH in HEK293 cells but not breast cancer cells. SOCS-2 expression in both cell types was stimulated by E(2) but unaffected by SERMs. In HEK293 cells, SHP-1 was inhibited by raloxifene and 4-hydroxytamoxifen, whereas the latter additionally inhibited SHP-2. The phosphatases were unaffected by E(2). In breast cancer cells, phosphatase activity was not altered by SERMs or E(2). In summary, estrogen inhibited the JAK2/STAT5 signaling of GH and stimulated SOCS-2 expression in both HEK293 and breast cancer cells. By contrast, SERMs augmented GH signaling by reducing SHP activities in HEK293 cells and had no effect on both in breast cancer cells. We provide the first evidence for a novel mechanism regulating GH signaling, in which SERMs enhance GH activation of the JAK2/STAT5 pathway in a cell-type-dependent manner by attenuating protein tyrosine phosphatase activities.

Genetic variation in IGF1, IGF-1R, IGFALS, and IGFBP3 in breast cancer survival among Chinese women: a report from the Shanghai Breast Cancer Study

Disruption of the balance of IGF (Insulin like growth factor) pathway constituents has been implicated in the etiology and progression of breast and other cancers. We hypothesized that genetic polymorphisms in IGF system members may be associated with breast cancer survival and evaluated this hypothesis in a cohort of 1,455 women diagnosed with breast cancer between 1996 and 1998 in Shanghai, China. Nineteen functional or potentially functional polymorphisms were evaluated in the IGF-1, IGF-1R, IGFALS, and IGFBP3 genes. Disease recurrence and vital status were obtained with a median follow-up time of 7.1 years. Cox proportional hazards models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI). Overall, no significant association was noted between any of the 19 polymorphisms and survival. However, subgroup analyses demonstrated apparent interactions between menopausal status and survival for several (Single nucleotide polymorphism) SNPs in the IGF-1R and IGFBP3 genes. Carriers of the A/G or G/G genotypes (rs951715) in the IGF-1R gene had an increased risk of death among post-menopausal women (HR = 1.7, 95% CI = 1.1-2.7). Significant associations with breast cancer survival in pre-menopausal women were found for two IGFBP3 polymorphisms (rs2854744 and rs3110697), with an additional polymorphism (rs6413441) reaching borderline significance (P = 0.05). Hazard ratios for overall survival among pre-menopausal women were 1.5 (95% CI = 1.1-2.0) for the C/T-T/T genotypes (rs3110697), 1.4 (95% CI = 1.0-1.9) for the A/C-C/C genotypes (rs2854744), and 1.4 (95% CI = 1.0-1.9) for the N/A-A/A genotypes (rs6413441). Taken together, these data suggest that polymorphisms in the IGF-1R and IGFBP3 genes may be associated with altered survival among subgroups of breast cancer patients defined by menopausal status.

Mammalian phytoestrogens: enterodiol and enterolactone

The mammalian phytoestrogens enterodiol (END) and enterolactone (ENL) are produced in the colon by the action of bacteria on the plant precursors matairesinol (MAT), secoisolariciresinol (SECO), their glycosides, and other precursors in the diet. Both END and ENL have been shown to possess weakly estrogenic and antiestrogenic activities, and it has been suggested that the high production of these antiestrogenic mammalian lignans in the gut may serve to protect against breast cancer in women and prostate cancer in men. Various in vitro experiments suggested END and ENL significantly inhibited the growth of human colon tumor cells, and the E2-induced proliferation of MCF-7 breast cancer cells was inhibited by ENL. The protective effects of mammalian lignans may be due to their ability to compete with E2 for the type II estrogen receptor, to induce sex hormone binding globulin (SHBG), to inhibit placental aromatase, and to act as antioxidants. This review mainly deals with the chemistry, quantitative analysis, biological properties and health effects of END and ENL.

Treatment of metastatic osteosarcoma with the somatostatin analog OncoLar: significant reduction of insulin-like growth factor-1 serum levels

BACKGROUND

Insulin-like growth factor-1 (IGF-1) has been implicated in the growth and/or metastasis of osteosarcoma (OS) and chondrosarcoma based on in vitro and experimental animal studies.

STUDY PURPOSE

To determine the degree of growth hormone (GH), IGF-1 axis blockade, toxicities, and antitumor effect of OncoLar (ONC) (Novartis, East Hanover, NJ, U.S.A.) in OS.

DESIGN/METHODS

A phase 1 study with ONC enrolled 21 OS patients (median age 19 y) in four cohorts: ONC 60 mg or 90 mg intramuscularly every 4 weeks with/without tamoxifen (TAM) 20 mg oral daily.

RESULTS

There were no dose-limiting toxicities. Nineteen percent of patients had grade III drug-related toxicities including: 62% of patients showed progressive disease after two courses (8 wk). Nineteen percent received four courses. No clinical responses were observed. At weeks two and eight of therapy, IGF-1 serum levels dropped 46% ( < 0.0001, n = 21) and 53% ( = 0.003, n = 10). The difference of the area under the curve (AUC) minus baseline AUC (DeltaAUC) for arginine-stimulated GH serum levels at week two was lower than baseline ( < 0.01). At weeks two and eight, GH peak values were lower than baseline ( < 0.0001 and = 0.002, respectively).

CONCLUSIONS

A long-acting somatostatin analog was able to lower IGF-1 levels of OS patients. IGF-BP-3 and GH were only transiently reduced. Although ONC was well tolerated, no sustained clinical responses were observed. The pathophysiology of serum versus tissue concentrations of IGF-1 as well as the interplay of IGFs, IGF-binding proteins, and other growth factors and cytokines in osteosarcoma warrants further investigation. A better understanding of these processes should lead to a more effective exploitation of these pathways for the targeted therapy of OS.

Breast cancer chemoprevention: current challenges and a look toward the future

There is a need to develop new prevention agents for breast cancer risk reduction that would have fewer side effects than the approved agent, tamoxifen, and/or would be effective in preventing estrogen receptor-negative or tamoxifen-resistant, estrogen receptor-positive breast cancers. There also is a need to improve the accuracy of present risk assessment models and to incorporate tissue-based biomarkers to supplement risk prediction tools. Candidate risk biomarkers include the serum hormones insulin-like growth factor-1 and its binding protein-3, mammographic breast density, nipple aspirate fluid production, and breast tissue evidence of proliferative breast disease (intraepithelial neoplasia). A variety of techniques have been developed to randomly sample breast tissue to detect precancerous changes and/or detect modulation of proliferation in response to a prevention agent. Based on molecular abnormalities observed in breast intraepithelial neoplasia, a number of drug classes and combinations are suggested as potential chemoprevention approaches. Clinical trial models have been developed to select the appropriate drug dose for subsequent biomarker modulation chemoprevention trials in which the use of surrogate endpoint biomarkers as indicators of efficacy is being explored. If these biomarkers can be validated and shown to reliably predict and monitor response in phase I/II prevention trials, and if favorable modulation is correlated with subsequent decreased cancer incidence, biomarkers may replace cancer incidence as the endpoint in future phase III trials, dramatically reducing the time and expense associated with new prevention drug development.

Induction of UO-44 gene expression by tamoxifen in the rat uterus and ovary

A complementary DNA, uterine-ovarian-specific gene 44 (UO-44), has been isolated from tamoxifen-induced rat uterine complementary DNA library using differential display techniques. UO-44 transcripts are found to be abundant in the uterus and ovary. UO-44 gene expression in the uterus is strictly regulated by estrogens, tamoxifen, and GH, whereas the pure antiestrogen ICI 182780 is inhibitory. Treatment of ovariectomized rats and hypophysectomized rats with tamoxifen and GH, respectively, resulted in up-regulation of UO-44 expression in a dose-dependent manner. In situ hybridization revealed that UO-44 gene expression was restricted to the luminal and glandular epithelial cells of the uterus and to granulosa cells of medium-size ovarian follicles. Transfection studies showed that UO-44 was a membrane-associated protein. Because estrogens, tamoxifen, and GH are stimulators of uterine luminal epithelial cell growth in vivo, UO-44 protein may serve as a mediator of the effect of these compounds in inducing epithelial proliferation and differentiation in these tissues.

Plasma insulin-like growth factor I levels in rats are reduced by dietary supplementation of flaxseed or its lignan secoisolariciresinol diglycoside

Flaxseed and its lignan secoisolariciresinol diglycoside (SDG) inhibit mammary tumor development in rats. Increased plasma insulin-like growth factor I (IGF-I) concentrations are associated with increased breast cancer risk. Therefore, the effect of flaxseed (5%) or SDG (1.5 mg/day) supplementation on plasma IGF-I levels was examined in rats treated with or without N-methyl-N-nitrosourea (MNU). In MNU-free rats, flaxseed and SDG reduced plasma IGF-I levels, which were inversely related to urinary lignan excretion. Only flaxseed significantly reduced plasma IGF-I concentrations in MNU-treated rats. The anticancer effect of flaxseed and SDG may be related, in part, to reductions in plasma IGF-I.

Inhibitory action on GHRH-induced GH secretion of chronic tamoxifen treatment in breast cancer

OBJECTIVE

Previous in vitro and in vivo studies on animal models have demonstrated that tamoxifen (TAM) inhibits GH secretion. Studies in humans are conflicting. The aim of this study was to evaluate the effect of chronic TAM treatment on GH secretory dynamics in the presence of negligible endogenous oestrogens, in postmenopausal women with breast cancer.

PATIENTS

Ten female patients were studied over a 6-12-month period after surgical therapy, before medical therapy, and during chronic treatment with TAM (20 mg/day p.o.).

MEASUREMENTS

In all subjects we performed a standard GHRH-test (50 mg i.v. as a bolus) and compared the single time points, the peak response and the areas under the curves (AUC), before and during treatment. In basal samples, we evaluated the circulating levels of IGF-1, IGF-BP3 and their ratio, SHBG, FSH, LH, Oestradiol (E2) and PRL. GH was assayed by Immunoradiometric assay (IRMA). Insulin-like growth factor type I (IGF-I), Insulin-like growth factor-binding protein-3 (IGF-BP3), FSH, LH and PRL were measured by Radioimmunoassay (RIA). SHBG was measured by a noncompetitive liquid phase immunoradiometric assay, while E2 was measured directly in plasma by a liquid phase technique.

RESULTS

TAM chronic treatment significantly reduced GH response to GHRH at single time point evaluations, GH peak response (mean decrease: 59.8 ± 7.3%) and GH-AUC (mean decrease 53.8 ± 8.9%). TAM also significantly reduced plasma IGF-1 levels. No significant variations were found in IGF-BP3 levels or in the IGF-1/IGF-BP3 ratio. A significant inverse correlation between SHBG and IGF-1 circulating levels was noticed during TAM treatment.

CONCLUSIONS

Our data show that long-term tamoxifen treatment blocks the response of GH to exogenous GHRH and reduces IGF-1 levels, possibly by a central mechanism other than the demonstrated peripheral action. The results of this study, keeping in mind the demonstrated mitogenic role of IGF-1 in cancer proliferation, can contribute to clarify the mechanism by which TAM exerts its antiproliferative effect.

Antiestrogens--tamoxifen, SERMs and beyond

Estrogens play a central role in reproductive physiology. The cellular effects of estrogens are mediated by binding to nuclear receptors (ER) which activate transcription of genes involved in cellular growth control. At least two such receptors, designated ERalpha and ERbeta, mediate these effects in conjunction with a number of coactivators. These receptors can directly interact with other members of the steroid receptor superfamily. A complex cross-talk exists between the estrogen-signaling pathways and the downstream signaling events initiated by growth factors, such as epidermal growth factor and insulin-like growth factors. Estrogens are also a causative factor in the pathogenesis of a variety of neoplastic and non-neoplastic diseases, including breast cancer, endometrial cancer, endometriosis, and uterine fibroids, among others. Antiestrogens, such as tamoxifen, are widely used for the treatment of breast cancer. Tamoxifen produces objective tumor shrinkage in advanced breast cancer, reduces the risk of relapse in women treated for invasive breast cancer, and prevents breast cancer in high-risk women. Although, initially developed as an antiestrogen, tamoxifen can also prevent postmenopausal osteoporosis as well as reduce cholesterol, due to its estrogen-agonist effects. Its estrogen-agonist activity, however, can lead to significant side-effects such as endometrial cancer and thromboembolic phenomena. This has led to the concept of "ideal" selective estrogen receptor modulators (SERMs), drugs that would have the desired, tissue selective, estrogen-agonist or -antagonist effects. Raloxifene is a SERM which has the desirable mixed agonist/antagonist effects of tamoxifen but does not cause uterine stimulation. "Pure" antiestrogens may provide very potent estrogen-antagonist drugs, but are likely to be devoid of beneficial effects on bone and lipids. Future drug development efforts should focus on developing superior SERMs that have a greater efficacy against ER-positive tumors and do not cause hot flashes or thromboembolism, and explore combination strategies to simultaneously target hormone-dependent as well as hormone-independent breast cancer.

Insulin-like growth factor binding proteins (IGFBPs) in breast cancer

The IGFBP family comprises six proteins with high affinity for the IGFs and several lower affinity IGFBP-related proteins. Their production in the breast is controlled by hormones, other local regulators and in tumors relates to the estrogen receptor status. Their functional activity can also be affected by various post-translational modifications. The IGFs are generally present at levels far in excess of that required for maximal receptor stimulation, and the IGFBPs are critical regulators of cellular action. IGFBPs can affect cell function in an IGF-dependent or independent manner. IGF bioactivity locally in the breast is influenced not only by local tissue expression and regulation of IGFs, IGFBPs, and IGFBP proteases, but also by these factors delivered from the circulation. Changes in the balance of the components of the IGF system may lead to a disruption of tissue homeostasis.

Liarozole fumarate (R85246): a novel imidazole in the treatment of receptor positive postmenopausal metastatic breast cancer

This phase II study of liarozole fumarate (R85246, liarozole), a novel imidazole with retinomimetic and aromatase inhibitory effects, was designed to determine the efficacy and tolerability in postmenopausal women with advanced breast cancer in progression, to correlate these effects with hormonal levels, and to evaluate quality of life. Twenty-nine women with ER-positive or unknown metastatic disease who received > or = 2 prior hormonal therapies were treated with 150-300 mg liarozole twice daily until disease progression. All patients were evaluable for toxicity and 25 for response. Four patients (16.0%, 95% CI 5.3-37.4%) had partial remission (PR) of their disease for a median of 7.4 months (range 1.2-12.9) and 7 (28%) had disease stabilization for a median of 4.8 months (1.6-16.0). Estradiol decreased from pre-treatment levels of 9.2-52 pM (mean 17.1) to below detection (9.2 pM, p = 0.0005) after 1 month. Similarly estrone levels fell from 14-307 pM (mean 92.7) to below detection (9.2 pM, p = 0.0001). The most common toxicity was dermatological (96.6%) with features compatible with hypervitaminosis A syndrome such as rash, pruritus, dry skin, and brittle nails. The majority of these were mild to moderate in severity. No significant improvement in quality of life scores (FLI-C) were noted. Liarozole is an active new treatment for breast cancer in patients heavily pre-treated with hormone therapies. Further studies are needed to confirm its relative efficacy in both receptor positive and negative postmenopausal breast cancer.

p53 down-regulates ER-responsive genes by interfering with the binding of ER to ERE

Overexpression of the tumor suppressor p53 in HeLa cells leads to loss of the estradiol- and genistein-induced human estrogen receptor (ERalpha) transactivity. The coactivator p300, which binds to both ERalpha and p53, does not prevent this loss of hERalpha function. In this report we demonstrate that p53 physically binds to multiple domains of the hERalpha. This binding did not interfere with either the ERalpha dimerization or the interaction between hERalpha and its coactivator SRC-1. However, p53 did interfere with the hERalpha-ERE binding. These results may explain how p53 down-regulates the expression of some estrogen-responsive genes such as c-fos, c-jun, TPA, and bcl-2. This study supports the cross-talk between the p53 and the ERalpha signaling pathways.

Growth hormone receptor antagonists therapy for acromegaly

Knowledge of the interaction between growth hormone (GH) and the growth hormone receptor (GHR) has led to the rational design of a GHR antagonist. An analogue of GH able to block the action of GH at the cellular level offers greater specificity of effect compared with current medical therapies and is not dependent on tumour characteristics. This chapter reviews the interaction between GH and the GHR, and discusses the outstanding issues regarding GHR antagonist therapy in acromegaly.

Enhancement of insulin-like growth factor signaling in human breast cancer: estrogen regulation of insulin receptor substrate-1 expression in vitro and in vivo

Cross-talk between insulin-like growth factor (IGF)- and estrogen receptor (ER)-signaling pathways results in synergistic growth. We show here that estrogen enhances IGF signaling by inducing expression of three key IGF-regulatory molecules, the type 1 IGF receptor (IGFR1) and its downstream signaling molecules, insulin receptor substrate (IRS)-1 and IRS-2. Estrogen induction of IGFR1 and IRS expression resulted in enhanced tyrosine phosphorylation of IRS-1 after IGF-I stimulation, followed by enhanced mitogen-activated protein kinase activation. To examine whether these pathways were similarly activated in vivo, we examined MCF-7 cells grown as xenografts in athymic mice. IRS-1 was expressed at high levels in estrogen-dependent growth of MCF-7 xenografts, but withdrawal of estrogen, which decreased tumor growth, resulted in a dramatic decrease in IRS-1 expression. Finally, we have shown that high IRS-1 expression is an indicator of early disease recurrence in ER-positive human primary breast tumors. Taken together, these data not only reinforce the concept of cross-talk between IGF- and ER-signaling pathways, but indicate that IGF molecules may be critical regulators of estrogen-mediated growth and breast cancer pathogenesis.

An experimental model of diabetes and cancer in rats

The aim of this study was to develop an experimental model for the study of cancer associated with diabetes. For diabetes induction, Sprague-Dawley rats were given streptozotocin (STZ, 90 mg/kg body weight (BW), by intraperitoneal injection on the second day of life. For mammary tumour induction, rats were injected with 50 mg/kg BW of N-nitroso-N-methylurea (NMU) at 50, 80 and 110 days old. The neoplastic process and the effect of tamoxifen treatment was examined in non-diabetic and diabetic rats. The latency period, NMU-induced tumour incidence and the number of tumours per rat in diabetic rats versus controls were 117 +/- 7 days versus 79 +/- 9 days (P < 0.001); 93% versus 95% (NS); and 5.2 +/- 1.6 versus 2.7 +/- 0.5 (P < 0.02). A more benign histological pattern for tumours in diabetic animals was observed. Mammary tumours in diabetic rats grew more slowly than in controls. Tamoxifen (1 mg/kg/day) treated diabetic rats showed tumour regression in 67% of NMU-induced mammary tumours versus 53% in controls (NS). Our results show that tumour progression seems to be affected by diabetes in this experimental model. We suggest this is the result of changes to insulin-like growth factors and their receptors, which occur in diabetics, and our future research will examine this hypothesis.

Tamoxifen does not improve survival of patients with advanced hepatocellular carcinoma

To discover whether tamoxifen is able to extend the survival of patients with advanced hepatocellular carcinoma, we included 80 patients with cirrhosis and advanced hepatocellular carcinoma in a multicenter, double-blind, placebo-controlled trial in order to analyze the influence of treatment with tamoxifen on survival. The patients were randomized to receive tamoxifen, 40 mg/day (group 1), or placebo (group 2). Both groups were similar in age, sex, etiology of cirrhosis, biochemical, hematologic and hormonal parameters, morphology of the tumor (nodular vs multinodular or massive), Child-Pugh's score, and Okuda's stage. The 1-year survival rate was similar in both groups (30% in group 1 vs 37.8% in group 2; p = 0.31). Tamoxifen treatment was well tolerated by the patients. We conclude that tamoxifen does not extend the survival of patients with cirrhosis and advanced hepatocellular carcinoma.

IGF-independent regulation of breast cancer growth by IGF binding proteins

The human IGFBP family consists of at least seven proteins, designated as IGFBP-1, -2, -3, -4, -5, -6, and-7. IGFBPs 1-6 bind IGF-I and IGF-II with high affinity whereas IGFBP-7, a newly identified IGFBP, binds IGFs with lower affinity and constitutes a low-affinity member of the IGFBP family. IGFBPs serve to transport the IGFs, prolong their half-lives, and modulate their biological action. At the cellular level, IGFBPs can either potentiate or inhibit the mitogenic effects of IGFs, depending upon cell types and IGFBP species (IGF-dependent action of IGFBPs). However, recent studies have indicated that IGFBPs, especially IGFBP-3, potently inhibit breast cancer cell growth in an IGF-independent manner. The IGF-independent action of IGFBP-3 requires interaction with cell-surface association proteins, presumably putative IGFBP-3 specific receptors, and is responsible for growth inhibitory action of the known growth suppressing factors such as TGF-beta, retinoic acid, and antiestrogens in breast cancer cells. Thus, IGFBP-3 appears to be a major factor in a negative control system involved in regulating human breast cancer cell growth in vitro. IGFBP-7, representing a low affinity IGFBP, appears to function as an IGF-independent cell growth regulator in breast cancer cells. Overall structural similarity between IGFBP-7 and classical high affinity IGFBPs 1-6 suggests that the mechanisms of action and signaling pathways used by IGFBP-7 may provide insight into the IGF-independent actions of the high affinity IGFBPs. A fuller understanding of the IGF-independent action of IGFBPs will allow us to understand how the growth of neoplastic cells can be modulated by the IGF/IGFBP system, and how other growth factors or pharmacological agents can interface with this system.

IGF system components as prognostic markers in breast cancer

The insulin-like growth factor (IGF) family of ligands, receptors, and binding proteins can regulate breast cancer cell proliferation in vitro, and interruption of these pathways inhibits IGF-mediated cell proliferation. If the IGF family members are key regulators of breast cancer growth and progression in vivo, we would expect their expression to be an indicator of the prognosis of the disease. Thus, measurement of IGF expression may provide an indicator of the growth effect within a tumor, and provide new targets for treatment of the disease. In this review we will summarize the data generated thus far indicating that IGF family members are indicators of prognosis of breast cancer, and that measurement of the whole IGF family in concert may provide useful information for treatment strategies of breast cancer.

Paracrine/autocrine regulation of breast cancer by the insulin-like growth factors

Local environmental signals regulate the growth and development of both normal and malignant breast epithelium. Members of the insulin-like growth factor (IGF) family likely influence both of these processes. The localization of IGF2 to stroma specifically surrounding malignant breast epithelium indicates that this growth factor may play a critical role in the genesis or maintenance of this transformed phenotype. Recent studies have sought to understand the mechanism by which IGF2 expressing fibroblasts are localized to the periphery of malignant breast cancer cells. In addition, the consequences of the expression of IGF-signaling components likely expand beyond their direct effects on mitogenesis. Indirect effects predominantly associated with the IGF2 receptor could also influence the invasive potential of breast tumor cells.

Feasibility, endocrine and anti-tumour effects of a triple endocrine therapy with tamoxifen, a somatostatin analogue and an antiprolactin in post-menopausal metastatic breast cancer: a randomized study with long-term follow-up

Suppression of the secretion of prolactin, growth hormone and insulin-like growth factor 1 (IGF-1) might be important in the growth regulation and treatment of breast cancer. Because oestrogens may counteract the anti-tumour effects of such treatment, the combination of an anti-oestrogen (tamoxifen), a somatostatin analogue (octreotide) and a potent anti-prolactin (CV 205-502) might be attractive. In this respect, we performed a first exploratory long-term study on the feasibility of combined treatment and possible clear differences in endocrine and anti-tumour effects during such combined treatment vs standard treatment with tamoxifen alone. Twenty-two post-menopausal patients with metastatic breast cancer (ER and/or PR positive or unknown) were randomized to receive either 40 mg of tamoxifen per day or the combination of 40 mg of tamoxifen plus 75 microg of CV 205-502 orally plus 3 x 0.2 mg of octreotide s.c. as first-line endocrine therapy. An objective response was found in 36% of the patients treated with tamoxifen alone and in 55% of the patients treated with combination therapy. Median time to progression was 33 weeks for patients treated with tamoxifen and 84 weeks for patients treated with combination therapy, but the numbers are too small for hard conclusions. There was no difference in overall post-relapse survival between the two treatment arms. With respect to the endocrine parameters, there was a significant decrease of plasma IGF-1 levels in both treatment arms, whereas during combined treatment plasma growth hormone tended to decrease and plasma prolactin levels were strongly suppressed; in some patients insulin and transforming growth factor alpha (TGF-alpha) decreased during the triple therapy. Although there was no significant difference in mean decrease of plasma IGF-1 levels between the two treatment arms, combined treatment resulted in a more uniform suppression of IGF-1. Therefore, the addition of a somatostatin analogue and an anti-prolactin may potentially enhance the efficacy of anti-oestrogens in the treatment of breast cancer owing to favourable endocrine and possible direct anti-tumour effects. Large phase III trials using depot formulations (to increase the feasibility) of somatostatin analogues are warranted to demonstrate the potential extra beneficial anti-tumour effects of such combination therapy.

Long-term inhibitory effects of a novel anti-estrogen on the growth of ZR-75-1 and MCF-7 human breast cancer tumors in nude mice

The effects of the novel anti-estrogen EM-343 on the growth of 2 hormone-responsive human breast cancer tumors have been examined in athymic nude mice. At the low daily dose of 5 microg, EM-343 administered subcutaneously for 6 months completely blocked the stimulatory effect of endogenous estrogens on the growth of ZR-75-1 and MCF-7 tumors implanted in nude mice. In addition, uterine weight decreased by 60% while ovarian weight increased by 37%. Estrogen receptor (ER) levels measured by [3H]-labeled estrogen binding were markedly reduced (by 96%, 96% and 92%) in ZR-75-1 and MCF-7 tumors, and in the mouse uterus, respectively. Accompanying the decrease in ER, progesterone receptor levels were reduced by 79%, 87% and 76%, respectively, in the above-mentioned tissues following EM-343 treatment. Our data show the pure anti-estrogenic properties of EM-343 and its high potency as an inhibitor of growth of human ZR-75-1 and MCF-7 breast tumors in nude mice.

Tamoxifen attenuates glucocorticoid actions on bone formation in vitro

Tamoxifen is a synthetic estrogen analog which may regulate osteogenesis in vivo by virtue of its antiglucocorticoid properties. We have examined tamoxifen regulation of glucocorticoid-induced osteogenesis in two different in vitro bone systems: the chicken periosteal osteogenesis model (CPO) and rat bone marrow stromal cells (RBMC). Hormone uptake studies were conducted with the osteosarcoma cell line, ROS 17/2.8. In the CPO model, alkaline phosphatase (AP) activity and collagen synthesis were stimulated by the glucocorticoid dexamethasone (Dex; 0.1 microM). These Dex-mediated effects were inhibited by increasing concentrations of tamoxifen (10-100 microM). Similarly, in the RBMC model, Dex-dependent (0.01 microM Dex) mineralized tissue formation and AP activity were blocked by tamoxifen (0.1 microM). Although tamoxifen inhibited Dex-mediated increases of AP activity in ROS 17/2.8 cells, it did not inhibit uptake of 3H-Dex or of 3H-estrogen. Northern analyses showed that tamoxifen did not affect messenger RNAs (mRNAs) for AP. Tamoxifen did seem to reduce mRNA for collagen type I, but not bone sialoprotein, osteopontin, and osteocalcin. Dex-induced increases for all proteins mRNAs in the RBMC model were not reduced by tamoxifen. Similarly, tamoxifen had no effects on cellular proliferation. We conclude that tamoxifen has no direct effect on gene expression of bone-related proteins of osteoblastic cells. Further, in the ROS 17/2.8 cell line, the antiglucocorticoid properties of tamoxifen do not appear to be mediated through either Dex or estrogen receptors.

Dairy products and breast cancer: the IGF-I, estrogen, and bGH hypothesis

Research on the role of dietary factors in breast cancer causation has focused predominantly on fat intake. While some studies have examined associations between breast cancer rates and consumption of whole milk, there has been less attention given to dairy products in general. Dairy products contain both hormones and growth factors, in addition to fat and various chemical contaminants, that have been implicated in the proliferation of human breast cancer cells. This literature review evaluates the epidemiological and mechanistic evidence linking dairy consumption with breast cancer risk.

Hormone dependence of mammary tumors induced in rats by intraperitoneal NMU injection

The purpose of this work was to determine the hormone dependence of mammary tumors induced in Sprague-Dawley rats by three intraperitoneal injections of N-nitroso-N-methylurea at 50, 80, and 110 days of age. Two experimental designs were carried out: (a) Ten days before the first NMU injection, 130 rats were divided into 13 batches and randomly assigned to the following treatments: control, ovariectomy (OVX), tamoxifen (TAM), bromocriptine (BROM), haloperidol (HAL), estradiol (E2), progesterone (Pg), OVX + BROM, TAM + BROM, OVX + HAL, TAM + HAL, OVX + TAM, and E2 + BROM. After 150 days of treatment the following growth parameters were determined: latency period (LP), mean tumor number per rat (n/t), and tumor incidence (TI). LP was significantly increased (p < 0.05) only by Pg and TAM + BROM. The n/t was significantly decreased (p < 0.05) by all treatments except HAL. TI was significantly reduced by OVX, TAM, BROM, and their combinations, (b) Rats bearing ip-NMU-induced mammary tumors were divided into 7 batches and assigned to the following treatments: control, OVX, TAM, BROM, HAL, OVX + BROM, and TAM + BROM. Tumor growth was assessed up to 60 days of treatment; only OVX, TAM and their combination with BROM were able to produce tumor regression. These results support the essential role of E2 and prolactin in the promotion stage of carcinogenesis. However, for established tumors, growth becomes more independent from hormone influence, in particular from prolactin deprivation. We conclude that this model seems suitable for studying the mechanisms underlying the evasion of hormonal control of tumor growth.

Associations between insulin-like growth factors and their binding proteins and other prognostic indicators in breast cancer

Recent studies have suggested that insulin-like growth factors (IGFs) and insulin-like growth factor binding proteins (IGFBPs) may be implicated in the development and progression of breast cancer. Prostate-specific antigen (PSA), a serine protease, may play a role in the regulation of IGFs' function through cleavage of IGFBP-3, resulting in release of active IGFs from IGFBP-3. As IGFs, IGFBPs and PSA are all present in breast cancer, possible associations among these proteins were speculated. In this study, we have measured PSA, IGF-I, IGF-II, IGFBP-1 and IGFBP-3 in tumour tissue cytosols from 200 women with primary breast cancer, and have examined relationships between IGFs or IGFBPs and PSA along with other markers, including p53 protein, steroid hormone receptors (oestrogen and progesterone), cathepsin-D, epidermal growth factor receptor, Her-2/neu protein, S-phase fraction and DNA ploidy. Correlations or associations between PSA and IGF-I, IGF-II, IGFBP-1 or IGFBP-3 were not observed. IGF-II was positively correlated with both IGFBP-3 and IGFBP-1. IGF-I was not associated with either of the two binding proteins, nor with IGF-II. Both IGF-II and IGFBP-3 were inversely associated with the oestrogen receptor, and IGFBP-3 was also positively associated with S-phase fraction. Our finding of IGF-II and IGFBP-3 in association with unfavourable prognostic indicators of breast cancer suggests that IGFs may be involved in the progression of breast cancer.

Effect of tamoxifen on intraperitoneal N-nitroso-N-methylurea induced tumors

The effect of tamoxifen (TAM) was evaluated on a mammary tumor model induced in Sprague-Dawley rats by intraperitoneal administration of three N-nitroso-N-methylurea (NMU) doses. Animals received TAM (1 mg/kg per day) from 10 days before the first NMU dose up to 140 days later. Thereafter, treatment was discontinued and the observation period was extended 60 days longer. Mean overall latency period, tumor number per rat and tumor incidence were recorded. Significant differences between treated and control batches were observed in tumor number per rat (1.8 +/- 1.1 versus 5.2 +/- 1.6; P < 0.05) and in tumor incidence (50% versus 100%; P < 0.05), respectively. No significant difference in latency period between both batches was recorded. All lesions induced in the control batch were malignant, whereas only 45% of those induced in TAM-treated animals were malignant and the remaining 55% were preneoplastic. At 60 days after treatment discontinuance, tumor incidence increased to 90% and also tumor number per rat increased to 4.6 +/- 1.5. TAM effect was also evaluated in rats with NMU-induced tumors by treatment with 1 mg/kg per day during 60 days starting when tumors reached a 1.5-cm diameter. Regression to less than 80% of initial size in 49% of the tumors was observed, while in ovariectomized rats, 33% of tumors regressed. Estrogen receptor content, ER (fmol/mg protein) and Kd (nM) in control tumors were: 56 +/- 10 and 0.5 +/- 0.1. In tumors of TAM-treated animals, ER was less than 5 fmol/mg protein. Findings demonstrate that TAM significantly decreased the appearance of tumors induced in rats by i.p. injection of NMU and when TAM treatment was initiated after tumor induction, some tumors failed to respond to hormonal manipulation. Differential tumor growth response after TAM or oophorectomy in each tumor indicates that in the same rat it is possible to distinguish hormone-dependent and hormone-autonomous tumor populations. Hormonal regulation of tumor growth can be under intrinsic control, regardless of the hormonal status of the whole organism.

Expression of receptors for epidermal growth factor and insulin-like growth factor I by ZR-75-1 human breast cancer cell variants is inversely related: the effect of steroid hormones on insulin-like growth factor I receptor expression

We have investigated the expression of insulin-like growth factor I receptors (IGFR) by the ZR-75-1 human breast cancer cell line and tamoxifen-resistant (ZR-75-9a1) and oestrogen-independent (ZR-PR-LT) variants. ZR-75-1 cells expressed 6633+/-953 receptors per cell,(K(d) 0.24+/-0.06 nM). IGFR expression was reduced in ZR-75-9a1 cells (1180+/-614 receptors per cell, K(d) 0.13+/-0.05) and increased in the ZR-PR-LT cell line (18 430+/-3210 receptors per cell, K(d) 0.24+/-17). A comparison of these data with previously published findings for epidermal growth factor receptor (EGFR) expression by these cell lines revealed that IGFR and EGFR expression are inversely related in the variant lines whereas ZR-75-1 cells express similar numbers of both receptors. Since the changes in IGFR expression observed are associated with changes in steroid hormone receptor status, we also investigated the effects of oestradiol, the synthetic progestin ORG 2058 and dexamethasone on IGFR expression. Oestradiol increased IGFR expression only in the ZR-75-1 cell line. Low concentrations of ORG 2058 increased IGFR levels in the two cell lines positive for progesterone receptor (ZR-75-1 and ZR-PR-LT). High concentrations of ORG 2058 increased IGFR expression in all cell lines, as did dexamethasone. These data suggest that EGFR and IGFR expression may be linked in breast cancer, and that EGFR/IGFR ratios in breast cancer may be a more sensitive prognostic indicator than EGFR expression alone. Regardless of basal IGFR expression by the cell studied, ORG 2058 increased IGFR expression, possibly via both the progesterone and glucocorticoid receptors.

Inhibition of endothelial adhesion and invasion by breast carcinoma cells may contribute towards the anti-metastatic effects of tamoxifen

The anti-metastatic actions of tamoxifen on the oestrogen receptor-(ER-) positive cell line, MCF-7 and Hs578T, which is ER-negative, were investigated by measuring changes in the tumour cell adherence to endothelium and invasion of Matrigel. The endothelial hybridoma EA.hy926 was grown to confluence on the bases of 96-well plates. Either tamoxifen, the pure ER antagonist ICI 182,780 or the control, phosphate-buffered saline (PBS), was added to each well in varying concentrations. Adhesion of tumour cells to the endothelium was then measured using an isotopic adhesion assay. Invasion was determined by measuring the number of cells passing across a Matrigel-coated filter with 8 microm diameter pores. After 24-h incubation, the number of cells which had invaded was determined by an XTT colorimetric assay. Tamoxifen and ICI 182,780 inhibited both adhesion to the model endothelium and Matrigel invasion of the ER-positive cell line at therapeutic concentrations (P<0.005). Neither compound, however, had an effect on the ER-negative cell line. This action of the ER antagonists may play a role in prolonging the disease-free survival seen in women with breast cancer who are treated with adjuvant tamoxifen.

Unlabeled milk from cows treated with biosynthetic growth hormones: a case of regulatory abdication

Levels of insulin-like growth factor-1 (IGF-1) are substantially elevated and more bioactive in the milk of cows hyperstimulated with the biosynthetic bovine growth hormones rBGH, and are further increased by pasteurization. IGF-1 is absorbed from the gastrointestinal tract, as evidenced by marked growth-promoting effects even in short-term tests in mature rats, and absorption is likely to be still higher in infants. Converging lines of evidence incriminate IGF-1 in rBGH milk as a potential risk factor for both breast and gastrointestinal cancers.