Serum insulin-like growth factor-I and breast cancer

Insulin-like growth factor I (IGF-I) is a systemic hormone with potent mitogenic and anti-apoptotic properties, which could influence the proliferative behavior of normal breast cells. Limited epidemiological observations suggest that the hormone may play a role in the etiology of breast cancer, especially at pre-menopausal ages. In a prospective case-control study nested within a cohort of New York City women, IGF-I, IGF-binding protein 3 (IGFBP-3) and C peptide were measured in frozen serum samples from 172 pre-menopausal and 115 post-menopausal subjects who were subsequently diagnosed with breast cancer. Subjects were eligible if diagnosed 6 months or more after recruitment into the study (7 to 120 months). Cohort members who matched the cases on age, menopausal status, date of blood sampling and day of menstrual cycle at blood collection served as controls. Post-menopausal breast cancer was not associated with serum IGF-I, IGFBP-3 or C-peptide levels. However, the risk of breast cancer increased with increasing serum concentrations of IGF-I in pre-menopausal women. The odds ratio (OR) for the highest quartile of IGF-I (>256 ng/ml) compared to the lowest (<168 ng/ml) was 1.60 [95% confidence interval (CI) 0.91-2. 81]. The OR decreased to 1.49 (95% CI 0.80-2.79) after adjustment for IGFBP-3. In analyses restricted to subjects who were pre-menopausal at the time of blood sampling and whose cancer was diagnosed before age 50, the top vs. bottom quartile OR increased appreciably to 2.30 (95% CI 1.07-4.94). Adjustment for IGFBP-3 reduced the OR to 1.90 (95% CI 0.82-4.42). There was no association between pre-menopausal breast cancer and IGFBP-3, IGF-I:IGFBP-3 ratio or non-fasting levels of C peptide. Elevated circulating levels of IGF-I may be an indicator of increased risk of breast cancer occurring before age 50.     

Down-regulation of insulin-like growth factor-I receptor and insulin receptor substrate-1 expression in advanced human breast cancer

The ligands, receptors and related signaling proteins of the insulin-like growth factor family are involved in the regulation of breast-cancer cell growth. We investigated the expression pattern of insulin-like growth factor-I receptor (IGF-IR), insulin receptor (IR) and insulin receptor substrate-1 (IRS-1), a core downstream signaling protein, in 69 primary breast-cancer specimens of different grades and in 21 control tissues by immunohistochemistry. In addition, cell proliferation (percentage of Ki67(+) nuclei) and estrogen receptor (ER) expression were determined. IGF-IR, IRS-1 and IR were expressed mainly in epithelial cells. IRS-1 and IGF-IR were expressed at high levels in control tissues and in well and moderately differentiated carcinomas but at low levels in poorly differentiated breast cancers. IR expression did not show a significant correlation with the differentiation grade of the tissues investigated. Statistical analysis (ROC analysis for tumor grade) demonstrated that down-regulation of IGF-IR and IRS-1 correlated better with tumor progression than reduction of ER expression or increase in cell proliferation, IGF-IR showing the best correlation, followed by IRS-1 and, less significant, ER and Ki67. Our findings clearly show that progression of breast cancer is accompanied by a reduction of IGF-IR/IRS-1 expression and that IGF-IR/IRS-1 expression inversely correlates with high proliferation rate in dedifferentiated breast cancers. The strong correlation of IGF-IR and IRS-1 down-regulation with tumor progression suggests the use of IGF-IR and IRS-1 as a novel set of marker proteins for tumor grading.     

Free insulin-like growth factor-I and breast cancer risk

Insulin-like growth factor-I (IGF-I) has mitogenic and anti-apoptotic effects on breast cancer cells. Epidemiologic studies have shown that high plasma levels of IGF-I and low levels of IGF binding protein (BP)-3 are associated with increased risk of breast cancer in premenopausal women. The actions of IGF-I are mediated through the IGF-I receptor (IGF-IR) and are regulated by IGFBPs. In circulation, most of the IGF-I binds to IGFBP-3, and binding of IGF-I to IGFBP-3 inhibits the actions of IGF-I. Since free IGF-I, which does not bind to IGFBPs, can readily cross the endothelial barrier to interact with IGF-IR, circulating free IGF-I is thought to be more relevant to the biologic activity of IGF-I. To examine the association of free IGF-I with breast cancer, we compared free IGF-I levels between 40 newly diagnosed breast cancer patients and 40 age- and race-matched healthy controls. Plasma levels of free IGF-I, total IGF-I and IGF-II, as well as total, intact and fragment IGFBP-3, were measured using commercial immunoassay kits. The association between IGF-I and breast cancer was examined using the conditional logistic regression analysis. Analysis of correlation (Spearman) showed that free IGF-I was correlated with total IGF-I and IGFBP-3 but not with IGF-II. The odds ratios for breast cancer patients having high plasma IGF-I (> or = median) after adjusting for menopausal status and IGFBP-3 were 2.00 (p < o r = 0.376) for total IGF-I and 6.31 (p < or = 0.047) for free IGF-I. A high ratio of IGF-I to IGFBP-3 was also associated with breast cancer (p < 0.05). No association was found for IGF-II, nor for total, intact and fragment IGFBP-3. The findings of this study suggest that measuring free IGF-I in circulation is more useful than measuring total IGF-I with respect to evaluation of an association between IGF-I and breast cancer risk.     

RUNX3、Bcl-2和Bax蛋白在乳腺癌中的表达及其意义

目的：检测乳腺癌组织中RUNX3、Bcl-2和Bax基因的表达,探讨它们的相关性及其临床意义。方法：采用免疫组织化学S-P法检测上述基因的表达。结果：RUNX3在乳腺癌中的阳性表达率为35.23%,明显低于在乳腺纤维腺瘤（85%）及乳腺增生病（87.5%）组织中的表达率,差别具有统计学意义（P〈0.05）。Bcl-2和Bax蛋白在良恶性乳腺病组织中的表达差别无统计学意义。RUNX3和Bcl-2蛋白表达与乳腺癌的临床分期、淋巴结转移呈负相关,Bcl-2蛋白表达与病理分级呈负相关。Bax蛋白的表达与临床分期、病理分级及淋巴结转移呈正相关。乳腺癌中RUNX3与Bcl-2蛋白的表达呈正相关（P〈0.05）,与Bax的表达无相关性（P〉0.05）。结论：三种蛋白对乳腺癌的发生发展起重要作用,在乳腺癌发展中RUNX3与Bcl-2起协同作用,检测乳腺癌组织中RUNX3、Bcl-2和Bax基因的表达对于评价患者的预后有一定价值。     

Radioimmunoassayable insulin-like growth factor-I in human breast cyst fluid

Insulin-like growth factor-I (IGF-I) was measured in breast cyst fluid and serum collected at the same time. In addition, epidermal growth factor (EGF) was measured in breast cyst fluid. The radioimmunoassay inhibition curve of cystic IGF-I was parallel to that of authentic IFG-I. Cystic immunoreactive IGF-I had an elution pattern similar to IGF-I from Sep-Pak C₁₈ silica columns and from gel-filtration chromatography using Sephacryl 200. The material from Sephacryl 200 gave a radioimmunoassay curve which was parallel to IGF-I.The median (range) amount of IGF-I in cyst fluid was 9.3 ng/ml (0.8–33.3 ng/ml) and was 5–10% of that found in serum, although there was no significant correlation between the two levels. The median (range) level of cystic EGF was 416 ng/ml (14–1640 ng/ml). There was a weak negative correlation between cystic EGF and cystic IGF-I (P < 0.01).Some women presented with multiple cysts and for these cysts there was a high degree of concordance of levels for both IGF-I or EGF.Unlike serum there was little or no protein present in cyst fluid which bound IGF-I.     

Variant estrogen receptor alpha mRNAs in human breast cancer specimens

A panel of human breast cancer specimens was examined for single base change mutations by DNA sequencing and for larger deletions using a PCR-based assay. In the cancer specimens examined, no sequencing variants were detected other than a previously characterized polymorphism. Although most of the specimens contained estrogen receptor (ER) variants at a low level, 2 of 118 specimens exhibited variants which, after amplification, constituted most of the amplified ER cDNA. One specimen contained a single variant form, and there was little evidence of the wild-type ER mRNA by PCR, Northern blotting or immunocytochemistry. The second specimen, despite the presence of a normal-sized mRNA by Northern blotting and normal immunocytochemical staining for ER, contained at least 5 different variant forms as well as the wild-type ER. All but 1 of the variant forms were processing variants, and 3 of these processing variants have not been described before. One variant, although lacking exons 2-4, has break points in exons 1 and 5 that do not correspond to intron-exon boundaries. This variant might reflect more widespread damage to the genome in this breast cancer specimen. The low level of occurrence of variants suggests that ER variant forms, at least in the coding region, do not contribute generally to the progression of breast cancer.     

乳腺癌组织缺氧与雌激素受体-α的关系

目的:缺氧是乳腺癌常见的现象,并可能诱导肿瘤的进展。雌激素受体(ER)-α状态是乳腺癌预后和内分泌治疗疗效的重要预测指标。本研究旨在揭示乳腺癌中缺氧与ER-α表达的关系。方法:51例患者经配体结合法证实为ER阳性的乳腺癌。采用免疫组织化学染色的方法观察ER-α的异质性表达与多种缺氧标志的关系。结果:免疫组织化学染色发现本组有49例乳腺癌为ER-α阳性。无论乳腺导管内癌(n=29)还是浸润性癌(n=20),ER-α蛋白在邻近坏死灶的区域都出现了下降(P分别≤0.0001);ER-α的区域性下调还与缺氧诱导基因CA-Ⅸ和Glut-1的表达有关(P<0.0001)。结论:乳腺癌中ER-α区域性的表达下降与缺氧有关。因此缺氧可能促使乳腺癌在进展过程中向ER-α阴性的表型演变。     

Prostate cancer risk in relation to selected genetic polymorphisms in insulin-like growth factor-I, insulin-like growth factor binding protein-3, and insulin-like growth factor-I receptor.

We conducted a nested case-control study within a cohort of elderly Americans to examine the role of the insulin-like growth factor (IGF) signaling pathway in prostate cancer etiology. The distribution of genotypes of IGF-I (CA)n, IGF binding protein-3 (IGFBP-3) A-202C, and of the 2-bp deletion and (AGG)n polymorphisms in IGF-I receptor (IGF-IR) was compared between men with prostate cancer (n = 213) and equal number of controls matched on year of blood draw, survival until the date of diagnosis, race, and age. Among controls, the number of CA repeats in IGF-I was not correlated to any appreciable degree with plasma IGF-I concentration, whereas the IGFBP-3 CC genotype was associated with a relatively low level of plasma IGFBP-3. There was no association between prostate cancer risk and the number of CA repeats in IGF-I, IGFBP-3 genotype, or the presence of the 2-bp deletion in IGF-IR. There was a small increased risk among men who did not carry two copies of the (AGG)7 allele of IGF-IR. These results add to the evidence that the number of IGF-I CA repeats is not associated with prostate cancer risk. Our observation that men who do not carry two copies of the IGF-IR (AGG)7 allele are at increased risk of prostate cancer merits further investigation.     

光动力作用对人乳腺癌细胞Bax和Bcl-2蛋白表达的实验研究

目的:探讨光动力作用(PDT)对人乳腺癌细胞Bax和 Bcl-2的影响.方法:体外培养的人乳腺癌细胞MDA-MB-231,分别在PDT作用不同时间后,用免疫组织化学法检测促凋亡蛋白Bax和抗凋亡蛋白Bcl-2 蛋白表达情况.结果:Bax蛋白表达在所有组无明显差异(P>0.05),Bcl-2蛋白表达自PDT后6h起显著下降(P<0.01);PDT后6h Bax/Bcl-2 比值依次递增,且有统计学义(P<0.05).结论:光动力作用可诱导人乳腺癌细胞发生凋亡,其机制可能与Bax和 Bcl-2 蛋白表达的比值有关.     

缺氧诱导乳腺癌雌激素受体α的下调

目的　探讨乳腺癌组织中雌激素受体α(ER α)的异质性表达与多种缺氧标志的关系。方法　 5 1例经配体结合法证实ER阳性的乳腺癌患者 ,采用免疫组织化学染色的方法观察其ER α的异质性表达与多种缺氧标志的关系 ,同时观察体外缺氧环境对乳腺癌细胞系ER α表达的影响及其特异性。结果　 4 9例乳腺癌为ER α阳性。无论乳腺导管内癌 (2 9例 )还是浸润性癌 (2 0例 ) ,ER α蛋白在邻近坏死灶的区域均下调 (P值分别≤ 0 .0 0 0 1) ;ER α的区域性下调还与缺氧诱导基因CA IX和Glut 1的表达有关 (P <0 .0 0 0 1)。缺氧可以直接诱导乳腺癌细胞系ER α蛋白和mRNA水平的下降 ,但其他一些应激因素 ,如低pH值、低糖及缺氧细胞的培养液等却无此作用。长时间、间歇性缺氧可以导致MCF 7细胞ER α表达的持久抑制。结论　乳腺癌ER α区域性的表达下降与缺氧有关 ,长时间、间歇性的缺氧可以持续性抑制ER α的表达。缺氧可能促使乳腺癌在进展过程中向ER α阴性的表型演变 ,并可能导致对内分泌治疗的耐药。     

Plasma insulin-like growth factor-I, insulin-like growth factor-binding proteins, and prostate cancer risk: a prospective study

BACKGROUND: Recent studies have suggested that men with elevated plasma levels of insulin-like growth factor-I (IGF-I) may have an increased risk of prostate cancer. Furthermore, IGF-binding proteins (IGFBPs) and insulin can modulate the activity of IGF-I. In this study, we sought to determine the role of IGF-I as well as IGFBPs-1, -2, and -3 and insulin as possible etiologic factors for prostate cancer. METHODS: We conducted a nested case-control study within the Northern Sweden Health and Disease Cohort Study. We measured levels of IGF-I, IGFBP-1, IGFBP-2, IGFBP-3, and insulin in plasma samples from 149 men who had a diagnosis of prostate cancer between 1 month and 10 years after blood collection and among 298 control men. All statistical tests are two-sided. RESULTS: Case subjects had statistically significantly higher mean levels of IGF-I than control subjects (229 ng/mL; 95% confidence interval [CI] = 218-240 ng/mL] versus 214 ng/mL [95% CI = 208-221 ng/mL]; P =.02) and IGFBP-3 (2611 ng/mL [95% CI = 2518-2704 ng/mL] versus 2498 ng/mL [95% CI = 2437-2560 ng/mL]; P =.04). Conditional logistic regression analyses showed increases in prostate cancer risk with rising levels of IGF-I (P:(for trend) =.02) and IGFBP-3 (P(for trend) =.03). In case subjects younger than 59 years at the time of blood collection, the risk associated with increased IGF-I was higher (P:(for trend) =.01), whereas the risk associated with increased IGFBP-3 was lower (P(for trend) =.44) than the corresponding risks in the full cohort. Prostate cancer risk was not associated with levels of IGFBP-1, IGFBP-2, or insulin. CONCLUSIONS: Prostate cancer risk is increased in men with elevated plasma IGF-I. This association was particularly strong in younger men in this study, suggesting that circulating IGF-I may be specifically involved in the early pathogenesis of prostate cancer.     

Oestrogen/insulin-like growth factor-I receptor interaction in early breast cancer: clinical implications.

The expression of oestrogen receptor (ER) and that of the insulin-like growth factor-I receptor (IGF-IR) are positively correlated in breast cancer specimens. Their function is strongly linked in enhancing proliferative activity in normal and malignant human mammary epithelial cells in culture. This review examines the likely role of such a mechanism in the increased breast cancer risk reported in postmenopausal women with abdominal obesity. Precancerous breast lesions show an increased proportion of ER-positive cells with high proliferative activity, and recent studies suggest that genetic mutations or epigenetic variants in the ER alpha gene may increase the ER's sensitivity to oestrogen stimulation. Abdominal obesity in women is associated with higher concentrations both of free oestradiol and free IGF-I. Activation of their respective receptors may induce synergistic stimulation of mammary carcinogenesis. However, there is clinical evidence that progression in precancerous breast lesions may be delayed or reversed. Involution occurs spontaneously in a proportion of duct carcinoma in situ (DCIS) (intraductal) lesions as women approach the menopause, and antioestrogen therapy has been shown to reduce recurrence and progression of DCIS lesions. Conclusions: Intervention trials in breast cancer prevention would greatly benefit from surrogate response markers which could predict long-term benefit. Changes in ER and IGF-IR expression apart from those in standardised cytomorphological criteria, might predict the likelihood of DCIS involution in cancer prevention trials. Future studies could involve examination of serial core biopsies from normal breast tissue during trials of antioestrogens, retinoids or weight-reduction interventions. Correlation of changes in these markers with changes in circulating IGF-I and oestradiol concentrations may help to clarify the roles of the markers.     

人表皮生长因子受体-2及雌激素受体与乳腺癌的关系

乳腺癌与人表皮生长因子受体-2及雌激素受体关系密切,这两种受体也是乳腺癌的分类标准和治疗靶点。在大多数乳腺癌患者中,人表皮生长因子受体-2信号途径和雌激素受体信号途径参与了细胞的增生存活过程。而且在乳腺癌病例中,人表皮生长因子受体-2和雌激素受体呈现出一定程度的负相关。这说明这两种受体活化后有一些联系。本文简要综述了人表皮生长因子受体-2和雌激素受体的联系以及这种联系在乳腺癌治疗中的意义。     

Expression of Bax in relation to Bcl-2 and other predictive parameters in breast cancer

Background: It has been suggested that modification of the physiologicalsusceptibility to induction of programmed cell death in transformedcells contributes to the pathogenesis of cancer. One of themajor regulators of cell death is the bcl-2 family. In breastcancer, altered expression of Bcl-2 has been described. Distributionof its counterpart Bax and the differential expression patternhave still to be evaluated. Patients and methods: Bax expression was investigated by immunohistochemistryin 122 primary breast cancers. Results were correlated withexpression of Bcl-2 and other variables of predictive value. Results: There was a positive association between Bax expressionand histological grading, (over)expression of c-erbB-1 and -2and proliferative activity. The correlation was most significantin cases where no concomitant Bcl-2 expression could be detected.In the same subgroup an inverse correlation with positivityfor estrogen (and progesterone) receptors was observed. Thepresence of Bax was not significantly associated with eithertumor type and size, nodal status or expression of c-erbB-3. Conclusion: Expression of Bax was coupled with negative histopathologicalfeatures, especially when expression of Bcl-2 was downregulatedconcomitantly. It may appear that alterations of the differentialBax/Bcl-2 expression pattern take part in deregulation of proliferationand loss of differentiation, thus playing an important rolein malignant progression. Bax, Bcl-2, breast cancer, prognostic factors     

The insulin-like growth factor-I receptor (IGF-IR) in breast cancer: biology and treatment strategies

Breast cancer is the most common cancer and the second leading cause of cancer-related deaths among women worldwide. Although patients are often diagnosed in the early and curable stages, the treatment of metastatic breast cancer remains a major clinical challenge. The combination of chemotherapy with new targeting agents, such as bevacizumab, is helpful in improving patient survival; however, novel treatment strategies are required to improve clinical outcomes. The insulin-like growth factor-I receptor (IGF-IR) is a tyrosine kinase cell surface receptor which is involved in the regulation of cell growth and metabolism. Previous studies have shown that activation of the IGF-IR signaling pathway promotes proliferation, survival, and metastasis of breast cancer cells. Additionally, overexpression of IGF-IR is associated with breast cancer cell resistance to anticancer therapies. Recently, IGF-IR has been introduced as a marker of stemness in breast cancer cells and there is also accumulating evidence that IGF-IR contributes to the establishment and maintenance of breast cancer epithelial-mesenchymal transition (EMT). Therefore, pharmacological or molecular targeting of IGF-IR could be a promising strategy, in the treatment of patients with breast cancer, particularly in order to circumvent the therapeutic resistance and targeting breast cancer stem/progenitors. Currently, many strategies have been developed for targeting IGF-IR, some have entered clinical trials and some are in preclinical stages for breast cancer therapy. In this review, we will first discuss on the biology of IGF-IR in an attempt to find the role of this receptor in breast cancer and then discuss about therapeutic strategies to target this receptor.     

Estrogen receptor beta2 negatively regulates the transactivation of estrogen receptor alpha in human breast cancer cells

Estrogens, by binding to and activating two estrogen receptors (ERalpha and ERbeta), are critically involved in the development of the mammary gland and breast cancer. An isoform of ERbeta, ERbeta2 (also called ERbetacx), with an altered COOH-terminal region, is coexpressed with ERalpha in many human breast cancers. In this study, we generated a stable cell line from MCF7 breast cancer cells expressing an inducible version of ERbeta2, along with endogenous ERalpha, and examined the effects of ERbeta2 on the ERalpha protein levels and function. We showed that ERbeta2 inhibited ERalpha-mediated transactivation via estrogen response element and activator protein-1 sites of reporter constructs as well as the endogenous genes pS2 and MMP-1. Chromatin immunoprecipitation assays revealed that ERbeta2 expression caused a significant reduction in the recruitment of ERalpha to both the pS2 and MMP-1 promoters. Furthermore, ERbeta2 expression induced proteasome-dependent degradation of ERalpha. The inhibitory effects of ERbeta2 on ERalpha activity were further confirmed in HEK293 cells that lack functional endogenous ERs. We also showed that ERbeta2 can interact with ERalpha both in vitro and in mammalian cells, which is compatible with a model where ERbeta2/ERalpha heterodimers are targeted to the proteasome. Finally, in human breast cancer samples, we observed that expression of ERbeta2 significantly correlated with ERalpha-negative phenotype. Our data suggest that ERbeta2 could influence ERalpha-mediated effects relevant for breast cancer development, including hormone responsiveness.