Bisphosphonates antagonise bone growth factors' effects on human breast cancer cells survival

Bone tissue constitutes a fertile 'soil' for metastatic tumours, notably breast cancer. High concentrations of growth factors in bone matrix favour cancer cell proliferation and survival, and a vicious cycle settles between bone matrix, osteoclasts and cancer cells. Classically, bisphosphonates interrupt this vicious cycle by inhibiting osteoclast-mediated bone resorption. We and others recently reported that bisphosphonates can also induce human breast cancer cell death in vitro, which could contribute to their beneficial clinical effects. We hypothesised that bisphosphonates could inhibit the favourable effects of 'bone-derived' growth factors, and indeed found that bisphosphonates reduced or abolished the stimulatory effects of growth factors (IGFs, FGF-2) on MCF-7 and T47D cell proliferation and inhibited their protective effects on apoptotic cell death in vitro under serum-free conditions. This could happen through an interaction with growth factors' intracellular phosphorylation transduction pathways, such as ERK1/2-MAPK. In conclusion, we report that bisphosphonates antagonised the stimulatory effects of growth factors on human breast cancer cell survival and reduced their protective effects against apoptotic cell death. Bisphosphonates and growth factors thus appear to be concurrent compounds for tumour cell growth and survival in bone tissue. This could represent a new mechanism of action of bisphosphonates in their protective effects against breast cancer-induced osteolysis.     

Bisphosphonates and jaw osteonecrosis in patients with advanced breast cancer.

BACKGROUND: In recent years, several cases of mandibular necrosis associated with long-term use of bisphosphonates have been reported. The estimated incidence varies from 1% to 4.6%. PATIENTS AND METHODS: We conducted an observational study with the aim of determining the incidence of jaw osteonecrosis in advanced breast cancer patients with bone metastases under bisphosphonate treatment and to identify subjects at higher risk of developing this complication evaluating preclinical signs. We considered two groups of patients. All the patients complaining of odontostomatological symptoms underwent maxillary CT scan and maxillo-surgeon clinical examination. Asymptomatic patients were asked to perform a standard orthopantomography (OPT). RESULTS: From February 2005 to October 2005, we observed five patients with jaw bone necrosis (6%). Diagnosis was radiological and clinical. In two patients a confirmatory biopsy was performed. In the same time interval, OPTs were collected from 76 asymptomatic patients. Three OPTs revealed radiological features of suspicious mandibular necrosis. Maxillary CT scan confirmed the presence of an osteolityc area with signs of periosteal reaction. All the three patients were referred to maxillo-surgeon and two out of three patients underwent mandibular biopsy, but histopathological results were not conclusive. CONCLUSIONS: In our experience, the incidence of jaw bone necrosis in breast cancer patients seems to be higher than in other reports (6%). Radiological features of suspicious jaw necrosis were observed in three asymptomatic patients. We do not know how these findings should be considered. Anyway, standard OPT is a simple procedure, and may allow identification of periodontal conditions that in some way can predispose to the development of this uncommon event.     

Bisphosphonates in breast cancer

Bisphosphonates are osteoclast inhibitors, currently being used in oncology to prevent or delay bone morbidity in cancer. Oral and intravenous formulations of bisphosphonates have been found to be efficacious in preventing skeletal‐related events such as bone pain, pathologic fractures, spinal cord compression and hypercalcemia of malignancy, in patients with bone metastatic breast cancer. Bisphosphonates are also used to prevent bone loss associated with anti‐estrogen therapy using aromatase inhibitors. In addition to its role in preventing bone resorption, several pre‐clinical studies have noted an anti‐tumor role as well. Recent research effort has particularly focused on investigating an adjuvant role for bisphosphonates in early breast cancer. Recently, few randomized trials have found a beneficial effect for adjuvant use of the aminobisphosphonate, zoledronate, in older patients who are post‐menopausal. This review article will summarize the various clinical studies investigating the role of bisphosphonates in breast cancer.     

低浓度乙醇诱导人胰腺癌细胞凋亡的实验研究

目的:探讨低浓度乙醇对胰腺癌细胞凋亡的诱导作用。方法:用含不同浓度乙醇（0%、2%、4%和6%）培养液培养胰腺癌细胞。CCK8法检测不同浓度乙醇对胰腺癌细胞增殖的影响,流式细胞仪检测细胞的凋亡。实时荧光定量PCR法检测凋亡相关基因caspase-8 mRNA、caspase-9 mRNA的表达水平变化,Western blot检测caspase-3蛋白表达水平的变化。结果:低浓度乙醇可抑制胰腺癌细胞的增殖,随着浓度的增加,细胞存活率明显下降,与对照组（0%组）相比均有统计学差异(P<0.05)。流式细胞仪检测显示2%、4%和6%乙醇组均可诱导细胞凋亡,与对照组（0%组）相比均有统计学差异(P<0.05)。caspase-8 mRNA在2%、4%和6%乙醇组的表达与对照组相比未见明显增加（P>0.05）,而caspase-9 mRNA在2%、4%和6%乙醇组中的表达均增加,且与对照组相比均有统计学差异（P<0.05）。活性caspase-3蛋白在2%、4%和6%乙醇组中均有表达,而对照组未见活性caspase-3蛋白的表达。结论:低浓度乙醇可诱导胰腺癌细胞凋亡。     

Prolactin acts as a potent survival factor for human breast cancer cell lines

Human breast cancer is the leading cause of cancer death in women from Western societies, and a large study of the epidemiology demonstrated strong associations between human prolactin and risk of breast cancer. Using established models of apoptosis of human breast cancer cell lines, we assessed the role of prolactin in breast cancer cell growth and survival. We showed that prolactin had no effect on the metabolic activity or total cell number of any cell lines. We confirmed endogenous prolactin production by these cells and that the levels varied. In the presence of a prolactin-neutralising antibody, each of the cell lines responded with the induction of apoptosis as opposed to growth inhibition. The sensitivity of the cell lines to the physiological inducer of apoptosis, C2-ceramide, appeared relative to the levels of endogenous prolactin that they contained. We then showed that exogenously added prolactin acted as a potent survival factor against apoptosis in all the cell lines examined. In addition, we demonstrated that a prolactin-neutralising antibody in combination with C2-ceramide caused an anticipated, additive increase in cell death. This study demonstrated that prolactin protects human breast cancer cell lines against apoptosis and this may have important implications for cancer treatment.     

桔梗皂苷D诱导乳腺癌MDA-MB-231细胞凋亡

目的:研究来自桔梗的天然单体化合物桔梗皂苷D(platycodin D,PD)对高转移性乳腺癌细胞MDA-MB-231凋亡的影响,初步探索其可能的作用机制.方法:以不同浓度(0、2.5、5、10 μmol/L)PD处理乳腺癌MDA-MB-231细胞后,采用MTT法检测细胞增殖率并计算IC50值,流式细胞术检测细胞凋亡情况,Western blotting检测凋亡相关蛋白的表达水平.结果:PD呈剂量依赖性显著抑制MDA-MB-231细胞的增殖(P＜0.01),作用72 h的IC50值为(7.30±2.67) μmol/L.与对照组相比,10 μmol/L的PD可显著促进MDA-MB-231细胞的凋亡(P＜0.05).PD激活了caspase家族蛋白,上调有活性的cleaved caspase-3、cleaved caspase-8和cleaved caspase-9的表达,下调无活性的caspase-8和caspase-9的表达;PD同时减少Bcl-2的表达,增加Bax的表达,使Bcl-2/Bax的比值降低.研究还发现PD使突变型P53蛋白的表达减少、E2F1的表达增加.结论:PD抑制乳腺癌细胞增殖具有明显的抗肿瘤效应,而诱导凋亡的发生可能是其发挥抗肿瘤效应的机制之一.     

Bisphosphonates for osteoporosis treatment are associated with reduced breast cancer risk

Background:

Bisphosphanates are used primarily for the prevention and treatment of osteoporosis, and are also indicated for osseous complications of malignancy. In addition to their bone resorption properties, the most commonly used nitrogen-containing bisphosphonate compounds also inhibit protein prenylation, and thus may exert anti-tumour properties.

Methods:

To evaluate whether the use of these drugs may be associated with cancer, specifically breast cancer, we conducted a population-based case–control study in Wisconsin from 2003 to 2006. Participants included 2936 incident invasive breast cancer cases and 2975 population controls aged <70 years. Bisphosphonate use and potential confounders were assessed by interview.

Results:

Using multivariable logistic regression, the odds ratio for breast cancer in current bisphosphonate users compared with non-users was 0.67 (95% confidence interval 0.51–0.89). Increasing duration of use was associated with a greater reduction in risk (P-trend=0.01). Risk reduction was observed in women who were not obese (P-interaction=0.005).

Conclusion:

These results are suggestive of an additional benefit of the common use of bisphosphonates, in this instance, the reduction in breast cancer risk.     

JNJ-7706621对人乳腺癌细胞周期及凋亡的影响

  目的   探讨周期素依赖性蛋白激酶（cyclin-dependent kinases,CDKs）抑制剂JNJ-7706621对人乳腺癌细胞周期及凋亡的影响。  方法  常规培养乳腺癌T47D、MD-MB-231细胞,MTT法检测不同浓度JNJ-7706621（0、1、2、4 μM）对乳腺癌细胞增殖的影响;流式细胞术检测JNJ-7706621对细胞周期的影响,Annexin Ⅴ-FITC/PI双染法检测JNJ-7706621对细胞凋亡的影响;West. ern blot检测JNJ-7706621对凋亡及周期相关蛋白表达的影响。  结果  JNJ-7706621能够抑制乳腺癌T47D、MDA-MB-231细胞增殖,具有浓度和时间依赖性;流式细胞术显示,JNJ-7706621可将T47D、MDA-MB-231细胞的周期阻滞于G2/M期,具有浓度依赖性,与对照组相比差异有统计学意义（P < 0.05）;Annexin Ⅴ-FITC/PI双染法示随着JNJ-7706621浓度增加或作用时间的延长,T47D、MDA-MB-231细胞凋亡所占比例逐渐增加,与对照组相比,差异有统计学意义（P < 0.05）;Western blot结果显示,随JNJ-7706621浓度增加,Bcl-2的表达明显下调,Caspase3、PARP的剪切明显增高,而p53的表达无明显变化;周期相关蛋白CDK1的表达无明显变化;CDK1在Thr161位点的磷酸化水平降低,而在Tyr15位点的磷酸化水平增高;  结论   在体外条件下,JNJ-7706621可通过阻滞细胞周期与诱导细胞发生凋亡的方式,有效抑制乳腺癌细胞增殖,可能与抑制CDK1在Thr161位点的磷酸化水平有关。      

Ganoderma lucidum extract induces cell cycle arrest and apoptosis in MCF-7 human breast cancer cell

Although the pharmacology and clinical application of water extracts of Ganoderma lucidum have been extensively documented, little is known regarding its alcohol extract. In the present study, the anti-tumor effect of an alcohol extract of Ganoderma lucidum was investigated using MCF-7 cells. We found that the alcohol extract of Ganoderma lucidum inhibited cell proliferation in a dose- and time-dependent manner, which might be mediated through up-regulation of p21/Waf1 and down-regulation of cyclin D1. Furthermore, this compound can directly induce apoptosis in MCF-7 cells, which might be mediated through up-regulation of a pro-apoptotic Bax protein and not by the immune system. Our findings suggest that there are multiple mechanisms underlying the anti-tumor effects of Ganoderma lucidum.     

Metastasis from human breast cancer cell lines

Summary Immunodeficient animals, principally nude mice, when used in appropriately designed studies have been shown to be useful for the experimental analysis of human breast cancer metastasis. As with many other human tumors, the implantation of breast cancer cells into an anatomically appropriate tissue (the mammary fatpad) results in increased tumor take and incidence of metastasis for certain cell lines compared with subcutaneous injection. Testing a number of widely available human breast cancer cell lines identified the MDA-MB-435 cell line as the most metastatic, producing lung and lymph node metastases in a high proportion of nude and severe combined immunodeficient (SCID) mice after injection in the mammary fatpad. Mixing human breast cancer cells with normal fibroblasts or with Matrigel also increases the tumor incidence and growth rates in nude mice. Different routes of injection can be used to assess the ability of human breast cancer cells to form metastatic lesions in the lungs (i.v. injection), the liver (injection in the spleen), the brain (direct or intracarotid artery injection) and the bone marrow and bone (injection into the left ventricle of the heart). These different approaches demonstrate the potential of experimental studies of human breast cancer growth and metastasis using immunodeficient mice; this model is valuable for experiments that test the role of metastasis-associated genes and the efficacy of novel forms of therapy.     

Staurosporine-induced apoptosis and hydrogen peroxide-induced necrosis in two human breast cell lines

The use of apoptosis-inducing agents in the treatment of malignant cancer is increasingly being considered as a therapeutic approach. In this study, the induction of apoptosis and necrosis was examined in terms of temporal dose responses, comparing a malignant and nonmalignant breast cell line. Staurosporine (SSP)-induced apoptosis and H(2)O(2)-induced necrosis were evaluated by two cytotoxicity assays, neutral red (NR) and methyl-thiazolyl tertrazolium (MTT), in comparison with a differential dye uptake assay, using Hoechst33342/propidium iodide (Hoechst/PI). Confirmatory morphological assessment was also performed by routine resin histology and transmission electron microscopy. Cell viability was assessed over a 0.5-48 h time course. In nonmalignant HBL-100 cells, 50 nM SSP induced 100% apoptosis after a 48 h exposure, while the same exposure to SSP caused only 4% apoptosis in metastatic T47D cells. Although complete apoptosis of both cell lines was induced by 50 microM SSP, this effect was delayed in T47D (24 h) compared with HBL-100 (4 h). Results also showed that neither MTT or NR can distinguish between the modes of cell death, nor detect the early onset of apoptosis revealed by Hoechst/PI.     

Bisphosphonates and pathologic complete response to taxane- and anthracycline-based neoadjuvant chemotherapy in patients with breast cancer

BACKGROUND:

Several studies have suggested that bisphosphonates have an antitumor effect. In the current study, the authors sought to evaluate whether the use of bisphosphonates increased the rate of pathological complete response (pCR) in patients with breast cancer.

METHODS:

The authors identified 1449 patients with breast cancer who were receiving taxane‐ and anthracycline‐based neoadjuvant chemotherapy between 1995 and 2007 at The University of Texas MD Anderson Cancer Center. Patients who received bisphosphonates for osteopenia or osteoporosis while receiving chemotherapy were also identified. The primary outcome was the percentage of patients achieving a pCR. Groups were compared using the chi‐square test. A multivariable logistic regression model was fit to examine the relation between the use of bisphosphonates and pCR. An exploratory survival analysis using the Kaplan‐Meier method was performed; groups were compared using the log‐rank test.

RESULTS:

Of the 1449 patients included, 39 (2.7%) received bisphosphonates. Those receiving bisphosphonates were older (P < .001) and less likely to be obese (P = .04). The pCR rate was 25.4% in the bisphosphonate group and 16% in the nonbisphosphonate group (P = .11). In the multivariable model, patients treated with bisphosphonates tended to have higher rates of pCR (odds ratio, 2.18; 95% confidence interval, 0.90‐5.24); however, the difference was not found to be statistically significant. With a median follow‐up of 55 months (range, 3 months‐145 months), no differences in disease recurrence or survival were observed.

CONCLUSIONS:

The use of bisphosphonates at the time of neoadjuvant chemotherapy was not found to be associated with a statistically significant increase in the rates of pCR. The observed estimates suggest a positive effect; however, the small percentage of patients receiving bisphosphonates likely affected the power to detect a statistically significant difference. Cancer 2011;. © 2011 American Cancer Society.     

HMG-I/Y in human breast cancer cell lines

The HMG-I/Y gene encodes the HMG-I and -Y architectural, chromatin binding proteins originally identified based on their association with chromosomal DNA. HMG-I/Y proteins bind to AT-rich regions in chromosomal DNA and alter gene expression. Increased HMG-I/Y protein expression also correlates with neoplastic transformation. Previous work from our laboratory has shown that HMG-I/Y is a direct c-Myc target gene involved in neoplastic transformation in Burkitt's lymphoma. We also observed that HMG-I/Y proteins have several oncogenic properties. In this report, we show that HMG-I/Y proteins are increased in several human breast cancer cell lines compared to a human breast cell line derived from normal breast cells. Decreasing HMG-I/Y proteins using an antisense ribozyme approach inhibits transformation in human breast cancer cells, suggesting that HMG-I/Y is important for the transformed phenotype observed in these cells. In addition, increased expression of the HMG-I isoform in normal human breast cells leads to transformation. These results suggest that HMG-I/Y is an oncogene important in the pathogenesis of human breast cancer. Although additional studies with animal models are needed, the antisense experiments, which result in blocking transformation suggest that this approach may have therapeutic potential in patients with breast cancer characterized by increased HMG-I/Y expression.     

Direct effects of bisphosphonates on breast cancer cells

In addition to inhibiting bone resorption, bisphosphonates have also been shown to exhibit antitumour effects. In vitro, bisphosphonates inhibit proliferation and induce apoptosis in cultured human breast cancer cells. In addition, bisphosphonate treatment interferes with breast cancer cell adhesion to bone matrix, and inhibits cell migration and invasion. The combination of bisphosphonates with other anticancer drugs such as the taxoids markedly enhances these effects. These newly recognized direct actions of bisphosphonates on breast cancer cells indicate that these agents may have a greater role to play in treatment of patients suffering from cancers with a propensity to metastasize to bone.     

维生素D对乳腺癌细胞及乳腺癌干细胞凋亡的影响

目的:探究维生素D对人乳腺癌细胞及乳腺癌干细胞凋亡的影响。方法:MTT法检测维生素D对乳腺癌SUM159细胞活力的影响;Hoechst33258染色检测维生素D对乳腺癌SUM159细胞凋亡的影响;实时定量PCR法检测维生素D对乳腺癌SUM159细胞凋亡相关分子Bax和Bcl-2 mRNA表达水平的影响;无血清悬浮培养法（serum-free medium,SFM）富集乳腺癌干细胞,显微镜下观察维生素D对乳腺癌干细胞球大小和数量的影响;实时定量PCR法检测维生素D对乳腺癌干细胞凋亡相关分子Bax、Bcl-2 mRNA表达水平的影响。结果:MTT法检测结果显示,维生素D可显著抑制乳腺癌细胞活力,且随着维生素D浓度升高,乳腺癌SUM159细胞活力的下降具有一定的剂量依赖效应,单因素方差分析显示,差异具有统计学意义(P＜0.01);Hoechst33258染色结果显示,维生素D可诱导乳腺癌SUM159细胞发生细胞凋亡形态改变;进一步PCR法检测结果显示,维生素D可显著上调乳腺癌SUM159细胞促凋亡蛋白Bax mRNA的表达,下调抗凋亡蛋白Bcl-2 mRNA的表达,单因素方差分析显示,差异具有统计学意义(P＜0.01)。SFM培养可有效富集乳腺癌干细胞,维生素D干预可明显抑制SFM富集的乳腺癌干细胞球的大小和数量,且与对照组相比,维生素D可显著上调乳腺癌干细胞球Bax mRNA的表达水平,下调Bcl-2 mRNA的表达水平,单因素方差分析显示,差异具有统计学意义(P＜0.01)。结论:维生素D可抑制乳腺癌细胞及乳腺癌干细胞活力,诱导乳腺癌细胞凋亡。     

Biological differences among MCF-7 human breast cancer cell lines from different laboratories

Summary MCF-7 human breast cancer cells are used widely for studies of tumor biology and hormone mechanism of action. Conflicting results have often been obtained in studies reported from different laboratories. In this report several biological properties were studied in four MCF-7 cell lines obtained from different laboratories. MCF-7 (ATCC), MCF-7, MCF-7 (KO), and MCF-7 (S) demonstrated similar morphology in monolayer culture. Chromosome analysis revealed that three of the lines shared several structural chromosome alterations and marker chromsomes; however, MCF-7 (ATCC) was distinctly different with virtually no chromosomal alterations shared in common with the other lines. All four lines contained variable amounts of estrogen receptor (ER) and progesterone receptor (PgR). The growth rate of MCF-7 (ATCC) was 50% slower than that of the other lines, and, unlike the other three lines, cell proliferation was unaffected by estrogen or antiestrogen treatment despite the presence of receptors. Cloning efficiency of the four lines varied over a 10-fold range. Tumorigenicity in athymic nude mice also varied considerably among these lines. MCF-7 (ATCC) grew well in ovariectomized nude mice, while the other lines required estrogen supplementation. MCF-7 (S) and MCF-7 grew rapidly with estrogen supplementation; MCF-7 (KO) grew very slowly. Antiestrogen therapy inhibited growth of MCF-7, MCF-7 (S), and MCF-7 (KO) tumors, but it had no effect on MCF-7 (ATCC). These data demonstrate that MCF-7 lines from different laboratories may have unique biological properties, despite having a similar karyotype (MCF-7, MCF-7 (S), MCF-7 (KO)). The fundamental differences in karyotype and biological properties of the MCF-7 (ATCC), and the previously reported differences in DNA restriction fragment polymorphism analyses, demonstrate that this line is derived from an entirely different patient. Investigators should carefully document the source and identity of MCF-7 cells used in published experiments.     

New cell lines of human breast cancer origin

Summary Established human mammary tumor cell lines constitute an important tool in the study of breast cancer. The aim of this work was to isolate and characterize two new mammary tumor cell lines, JCK and GCS, which were obtained from the pleural effusion and ascitic fluid, respectively, from two breast cancer patients. Both cell lines had some properties of transformed cells, namely immortalization and growth in soft agar. The carcinoma cells presented epithelial morphology shown by light and electron microscopy, and antigenic properties shown by different tumor markers such as a cytokeratin cocktail, carcinoembryonic antigen, epithelial membrane antigen, and human milk fat globule membrane antigen. A significant increase was also found (P>0.05) in cell growth and³H-thymidine incorporation into DNA in the JCK and GCS cell lines in the presence of 17 estradiol at concentrations of 10^–9 and 10^–7 M, respectively, after 5 days in culture. These cells presented estradiol receptor levels which were similar in the biopsies and the resulting cell lines. The aromatase activity was also similar in the JCK cell line and the original patient biopsy. However, there was a considerably higher aromatase activity in the GCS cell line than in the biopsy specimen. Southern hybridizations with theneu oncogene showed an additional 12 kb fragment in both cell lines, as also seen in patients with breast cancer. We conclude from these studies that thisin vitro system may provide us with a way to study metastatic cells and improve clinical management of breast cancer patients.     

人乳腺癌细胞凋亡与去磷酸化RB蛋白的关系

目的 :研究乳腺癌细胞凋亡与去磷酸化RB蛋白的关系。方法 :以乳腺癌细胞株MCF 7/S(化疗敏感细胞株 )和MCF 7/ADR(耐多柔比星细胞株 )为研究对象 ,用MTT比色法检测乳腺癌细胞的化疗敏感性 ;采用免疫细胞化学法检测多柔比星 (ADR)作用前后RB蛋白的表达状态 ;应用流式细胞术检测ADR诱导乳腺癌细胞凋亡程度。结果 :ADR能抑制敏感细胞MCF 7/S增殖 ,半数抑制浓度 (IC50 )为 0 .12 8μg/ml,而对应的耐药细胞MCF 7/ADRIC50值为 10 .89μg/ml,MCF 7/S细胞较MCF 7/ADR细胞对ADR敏感 86倍。加ADR前两种细胞胞核中的磷酸化RB蛋白均为阳性 ,去磷酸化RB蛋白均为阴性。经不同浓度ADR处理后 ,随着ADR浓度的增加 ,MCF 7/S细胞去磷酸化RB蛋白表达量逐渐增高 ,而MCF 7/ADR细胞去磷酸化RB蛋白表达量无明显增高。流式细胞术检测细胞凋亡和细胞周期 ,结果表明ADR诱导MCF 7/S细胞凋亡作用比MCF 7/ADR强 (P <0 .0 1)。结论 :乳腺癌MCF 7/S细胞凋亡与去磷酸化RB蛋白表达呈正相关 (P <0 .0 5 ) ,而MCF 7/ADR细胞凋亡与去磷酸化RB无明显相关 (P >0 .0 5 )。