Loss of B‐cell translocation gene 2 expression in estrogen receptor‐positive breast cancer predicts tamoxifen resistance

B‐cell translocation gene 2 (BTG2), a gene suppressed in a subset of aggressive breast cancer, is repressed by estrogen. BTG2 inhibits the expression of HER ligands and promotes AKT activation, which plays an essential role in the tamoxifen resistance of estrogen receptor (ER)‐positive breast cancer. To determine if BTG2 expression modifies tamoxifen efficacy, a cohort of 60 patients treated with adjuvant tamoxifen monotherapy was analyzed. We found that increased BTG2 expression showed better clinical survival and was the only independent prognostic factor for disease‐free survival (hazard ratio, 0.691; 95% confidence interval, 0.495–0.963; P = 0.029). Tamoxifen suppressed the human epidermal growth factor receptor 2 (HER2)‐Akt signaling in BTG2 expressing ER‐positive breast cancer cells with a correlated increase in sensitivity, whereas BTG2 knockdown abrogated this sensitivity. Consistent with this observation, tamoxifen significantly suppressed the growth ratio, tumor weight and Ki‐67 expression in BTG2 expressing breast cancer xenografts in mice. These studies demonstrate that BTG2 is a significant factor in tamoxifen response, acting through modification of AKT activation in ER‐positive/HER2‐negative breast cancer.     

High IKKα expression is associated with reduced time to recurrence and cancer specific survival in oestrogen receptor (ER)‐positive breast cancer

The aim of our study was to examine the relationship between tumour IKKα expression and breast cancer recurrence and survival. Immunohistochemistry was employed in a discovery and a validation tissue microarray to assess the association of tumour IKKα expression and clinico‐pathological characteristics. After siRNA‐mediated silencing of IKKα, cell viability and apoptosis were assessed in MCF7 and MDA‐MB‐231 breast cancer cells. In both the discovery and validation cohorts, associations observed between IKKα and clinical outcome measures were potentiated in oestrogen receptor (ER) positive Luminal A tumours. In the discovery cohort, cytoplasmic IKKα was associated with disease‐free survival (p = 0.029) and recurrence‐free survival on tamoxifen (p < 0.001) in Luminal A tumours. Nuclear IKKα and a combination of cytoplasmic and nuclear IKKα (total tumour cell IKKα) were associated with cancer‐specific survival (p = 0.012 and p = 0.007, respectively) and recurrence‐free survival on tamoxifen (p = 0.013 and p < 0.001, respectively) in Luminal A tumours. In the validation cohort, cytoplasmic IKKα was associated with cancer‐specific survival (p = 0.023), disease‐free survival (p = 0.002) and recurrence‐free survival on tamoxifen (p = 0.009) in Luminal A tumours. Parallel experiment with breast cancer cells in vitro demonstrated the non‐canonical NF‐κB pathway was inducible by exposure to lymphotoxin in ER‐positive MCF7 cells and not in ER‐negative MDA‐MB‐231 cells. Reduction in IKKα expression by siRNA transfection increased levels of apoptosis and reduced cell viability in MCF7 but not in MDA‐MB‐231 cells. IKKα is an important determinant of poor outcome in patients with ER‐positive invasive ductal breast cancer and thus may represent a potential therapeutic target.     

cJun overexpression in MCF-7 breast cancer cells produces a tumorigenic, invasive and hormone resistant phenotype

We have previously demonstrated decreased Jun/AP-1 activity in the breast cancer cell line MCF-7 when compared to normal or immortalized mammary epithelial cells. In this paper, we overexpress Jun in MCF-7 cells (MCF7Jun) and demonstrate that it results in diverse biologic and biochemical changes, which mimic those seen clinically in breast cancer. Overexpression of Jun causes significant alterations in the composition of AP-1, decreased junB and increased fra-1 expression and results in an increased biologic aggressiveness. MCF7Jun cells exhibit increased cellular motility, increased expression of a matrix degrading enzyme MMP-9, increased in vitro chemoinvasion and tumor formation in nude mice in the absence of exogenous estrogens. Furthermore, MCF7Jun cells are unresponsive to the growth stimulating effects of estrogen and growth inhibitory effects of tamoxifen. Analysis of the estrogen receptor (ER) expression and activity showed that the MCF7Jun cells have no detectable ER. MCF-7 cells overexpressing mutant forms of cJun were responsive to the growth stimulatory effects of estrogen indicating that full-length cJun is required to acquire the estrogen-independent phenotype in breast cancer cells.     

Reciprocal changes in gene expression profiles of cocultured breast epithelial cells and primary fibroblasts

The importance of epithelial‐stroma interaction in normal breast development and tumor progression has been recognized. To identify genes that were regulated by these reciprocal interactions, we cocultured a nonmalignant (MCF10A) and a breast cancer derived (MDA‐MB231) basal cell lines, with fibroblasts isolated from breast benign‐disease adjacent tissues (NAF) or with carcinoma‐associated fibroblasts (CAF), in a transwell system. Gene expression profiles of each coculture pair were compared with the correspondent monocultures, using a customized microarray. Contrariwise to large alterations in epithelial cells genomic profiles, fibroblasts were less affected. In MDA‐MB231 highly represented genes downregulated by CAF derived factors coded for proteins important for the specificity of vectorial transport between ER and golgi, possibly affecting cell polarity whereas the response of MCF10A comprised an induction of genes coding for stress responsive proteins, representing a prosurvival effect. While NAF downregulated genes encoding proteins associated to glycolipid and fatty acid biosynthesis in MDA‐MB231, potentially affecting membrane biogenesis, in MCF10A, genes critical for growth control and adhesion were altered. NAFs responded to coculture with MDA‐MB231 by a decrease in the expression of genes induced by TGFβ1 and associated to motility. However, there was little change in NAFs gene expression profile influenced by MCF10A. CAFs responded to the presence of both epithelial cells inducing genes implicated in cell proliferation. Our data indicate that interactions between breast fibroblasts and basal epithelial cells resulted in alterations in the genomic profiles of both cell types which may help to clarify some aspects of this heterotypic signaling. © 2009 UICC     

Amyloid precursor protein in human breast cancer: An androgen‐induced gene associated with cell proliferation

Amyloid precursor protein (APP) is a transmembrane protein that is highly expressed in brain tissue. Recently, APP has been implicated in some human malignancies, and its regulation by androgens has also been demonstrated. Such findings suggest the importance of APP in hormone‐dependent breast carcinoma, but APP has not yet been examined in breast carcinoma tissues. Therefore, in this study, we examined the biological and clinical significance of APP in breast carcinoma using immunohistochemistry and in vitro studies. APP immunoreactivity was detected in 57 out of 117 (49%) breast carcinoma tissues examined, and it was positively associated with androgen receptor (AR) expression. APP immunoreactivity was also significantly associated with Ki‐67 LI and increased risk of recurrence in the estrogen receptor (ER)‐positive cases, and was an independent prognostic factor in these patients. Subsequent in vitro experiments demonstrated that APP mRNA expression was significantly induced by biologically active androgen dihydrotestosterone in both a dose‐dependent and a time‐dependent manner in MCF‐7 breast carcinoma cells, which was potently suppressed by an AR blocker hydroxyflutamide. Moreover, cell proliferation activity of MCF‐7 and MDA‐MB‐231 cells was significantly associated with their APP expression level. These findings suggest that APP is an androgen‐induced gene that promotes proliferation activity of breast carcinoma cells. Moreover, APP immunohistochemical status is considered a potent prognostic factor in ER‐positive breast cancer patients.     

环氧化酶-2抑制剂nimesulide对乳腺癌细胞株增生、凋亡的影响

目的 探讨环氧化酶-2抑制剂nimesulide(NIM)对雌激素受体(ER)阴性(MDA-MB．231)和阳性(MCF-7)人乳腺癌细胞株增生、凋亡的影响。方法 应用MTT比色法分析细胞生长抑制作用，流式细胞技术测定细胞周期分布和凋亡率，透射电镜观察细胞形态与超微结构，AnnexinV法检测细胞的凋亡。结果 NIM以时间、剂量依赖性方式抑制MDA-MB-231(COX-2阳性)、MCF-7(COX-2阴性)细胞生长，阻滞细胞周期于G0／G1期，诱导细胞的凋亡，MDA—MB-231细胞对NIM的作用更为敏感。NIM对COX-2表达阴性的MCF-7细胞同样具有抑制增生、诱导凋亡的作用。结论 NIM对ER阳性和ER阴性乳腺癌细胞均有抑制增生、诱导凋亡的作用。NIM的抗肿瘤作用存在环氧化酶．2依赖性与非依赖性两种途径。     

Letrozole inhibits tumor proliferation more effectively than tamoxifen independent of HER1/2 expression status

BACKGROUND: The biological basis for the superior efficacy of neoadjuvant letrozole versus tamoxifen for postmenopausal women with estrogen receptor (ER)-positive locally advanced breast cancer was investigated by analyzing tumor proliferation and expression of estrogen-regulated genes before and after the initiation of therapy. METHODS: Tumor samples were obtained at baseline and at the end of treatment from 185 patients participating in a double blind randomized Phase III study of neoadjuvant endocrine therapy. These paired specimens were simultaneously analyzed for Ki67, ER, progesterone receptor (PgR), trefoil factor 1 (PS2), HER1 (epidermal growth factor receptor), and HER2 (ErbB2 or neu) by semiquantitative immunohistochemistry. RESULTS: The treatment-induced reduction in geometric mean Ki67 was significantly greater with letrozole (87%) than tamoxifen (75%; analysis of covariance P = 0.0009). Differences in the average Ki67 reduction were particularly marked for ER-positive tumors that overexpressed HER1 and/or HER2 (88 versus 45%, respectively; P = 0.0018). Twenty-three of 92 tumors (25%) on tamoxifen and 14 of 93 on letrozole (15%) showed a paradoxical increase in Ki67 with treatment, and the majority of these cases was HER1/2 negative. Letrozole, but not tamoxifen, significantly reduced expression of the estrogen-regulated proteins PgR and trefoil factor 1, regardless of HER1/2 status (P < 0.0001). ER down-regulation occurred with both agents, although levels decreased more with tamoxifen (P < 0.0001). CONCLUSION: Letrozole inhibited tumor proliferation to a greater extent than tamoxifen. The molecular basis for this advantage appears complex but includes possible tamoxifen agonist effects on the cell cycle in both HER1/2+ and HER1/2- tumors. A pattern of continued proliferation despite appropriate down-regulation of PgR expression with estrogen deprivation or tamoxifen was also documented. This observation suggests the estrogenic regulation of proliferation and PgR expression may be dissociated in endocrine therapy resistant cells.     

Alteration of Y-box binding protein-1 expression modifies the response to endocrine therapy in estrogen receptor-positive breast cancer

Y-box binding protein-1 (YB-1) plays an important role in tumor progression and drug resistance. This study examined whether YB-1 is involved in the alteration of response to endocrine therapy in estrogen receptor (ER)-positive breast cancer cells. MCF7 cells that stably expressed YB-1 (MCF7-YB-1) and vector control cells (MCF7-vector) were established. These cells were used to analyze the expression of the factors related to ER and growth factor receptor signaling pathways and responses to antiestrogens (tamoxifen and fulvestrant) and estrogen responsive element (ERE) activity. The effect of knocking down endogenous YB-1 expression was tested in wild-type MCF7 cells. In addition, the expression of YB-1 and the factors related to ER and growth factor receptor signaling pathways were evaluated in clinical breast cancers treated with preoperative chemotherapy. The expression of HER2, AIB1, p-Erk, and c-Myc was increased in MCF7-YB-1 cells. In contrast, knocking down of YB-1 decreased the expression of these factors but increased the expression of ERα in wild-type MCF7 cells. Furthermore, sensitivity to antiestrogens was decreased in the MCF7-YB-1 in comparison to that in MCF7-vector cells. The introduction of YB-1 into MCF7 cells inhibited apoptosis and cell cycle arrest at G1 phase induced by antiestrogens. In MCF7-YB-1 cells, the expression levels of p-Erk and c-Myc were continuously upregulated when cells were treated with either tamoxifen or fulvestrant. The ERE activity was reduced in MCF7-YB-1 cells in comparison to MCF7-vector cells, and the ERE activity in MCF7-YB-1 cells was inhibited by fulvestrant at a lower concentration than that which inhibited the ERE activity in MCF7-vector cells. In ER-positive clinical breast cancers treated with preoperative chemotherapy, significantly more number of specimens that showed increased or positive YB-1 expression after chemotherapy was positive for HER2 expression. These data suggest that alteration of YB-1 may modify the crosstalk between the ER pathway and HER2 pathway in ER-positive breast cancer cells, and consequently, may alter the response to endocrine therapy in ER-positive breast cancer cells.     

Protein phosphatase 1, regulatory subunit 15B is a survival factor for ERα‐positive breast cancer

Breast cancer is a heterogeneous disease at both the clinical and molecular levels. This heterogeneity may give rise to different therapy responses. Molecular profiling has facilitated identification of signatures for stratifying patients who would potentially benefit from given therapies. Previously, we reported on a subset of genes with the potential for predicting response of primary breast cancer to neoadjuvant chemotherapy. Herein, we report that patients with luminal (estrogen receptor α [ERα]‐expressing) breast cancer were enriched for nonresponders. To identify novel factors that contribute to the survival of breast cancer cells, a loss‐of‐function screen was performed with a subset of genes overexpressed in patients with disease resistant to chemotherapy. This approach led us to identify protein phosphatase 1, regulatory subunit 15B (PPP1R15B) as a factor with a potentially essential role in the survival of ERα‐positive breast cancer cells. Functional analyses showed that PPP1R15B depletion results in impaired proliferation due to unsuccessful transition of cells from G1 to S phase of the cell cycle, and apoptosis induction. Moreover, our data revealed a regulatory role for PPP1R15B in activating ERα. Furthermore, a high level of PPP1R15B mRNA expression was associated with poor outcome following tamoxifen‐based therapy. Accordingly, knockdown of PPP1R15B expression sensitized tamoxifen‐resistant MCF‐7 breast cancer cells to tamoxifen while reducing ERα abundance in these cells. Our findings reveal a novel role for PPP1R15B in the survival and therapy response of ERα‐positive breast cancer and may open new avenues for tumor subtype‐specific therapeutic strategies in the era of personalized medicine.     

Predictive value of SRC-1 for tamoxifen response of recurrent breast cancer

Tamoxifen causes an objective response in about one-third of metastatic breast cancer and in only half of the breast cancer patients with estrogen receptor (ER) positive tumors. Steroid-receptor coactivator-1 (SRC-1) appears to be a general coactivator for steroid receptors and rate limiting factor necessary for efficient ER transactivation. We aimed to evaluate whether SRC-1 expression is an additional factor for prediction of response to first-line tamoxifen therapy in patients who developed recurrent disease. Here for the first time, we report on SRC-1 expression using a semi-quantitative RT-PCR in 21 primary breast tumors, seven mammary tumor cell-lines, 12 fibroblast cultures, and six normal breast tissues. The highest levels of SRC-1 were observed in normal tissues, intermediate levels in tumor tissues, and the lowest levels in breast tumor cell-lines. There was no relationship between the levels of SRC-1 in these primary tumors and the proportion of tumor cells within the surgical samples, nor with ER status. The median SRC-1 level was, however, lower in tumors from patients that did not respond to tamoxifen. Our findings suggest that high levels of SRC-1 indicate a favorable response to tamoxifen of patients with recurrent breast cancer. Abbreviations: PgR, progesterone receptor; ER, estrogen receptor; GR, glucocorticoid receptor; TR, thyroid hormone receptor; RXR, retinoid X receptor; SRC-1, steroid-receptor coactivator-1; EGF, epidermal growth factor; TGF, transforming growth factor; IGF, insulin like growth factor; UPA, urokinase-type plasminogen activator     

Changes in Radiation Sensitivity and Steroid Receptor Content Induced by Hormonal Agents and Ionizing Radiation in Breast Cancer Cells in Vitro

Possible influences of tamoxifen and estradiol on in vitro radiation sensitivity and cellular receptor content after irradiation and/or tamoxifen treatment were studied in breast cancer cell lines; estrogen receptor (ER) and progesterone receptor (PgR) positive cell lines MCF-7 and MCF-7/TAM^R-1 and the ER and PgR negative cell line MDA-MB-231. The tamoxifen resistant MCF-7/TAM^R-1 cells were more resistant to ionizing radiation than the MCF-7 and MDA-MB-231 cells. Exposure to tamoxifen made the MCF-7 cells more radiation resistant, while estradiol made the MDA-MB-231 cells more radiation sensitive. A radiation dose of 6 Gy reduced the ER content in cytosol in both MCF-7 and MCF-7/TAM^R-1 cells, but brought no alterations to the PgR content. In MCF-7/TAM^R-1 cells tamoxifen exposure significantly increased the ER and reduced the PgR content, an effect not observed in the MCF-7 cells. To conclude, the present study indicates that irradiation and tamoxifen may modify the ER and PgR content in cytosol in breast cancer cells. Hormonal treatment may alter the radiation sensitivity, even in ER negative cells, suggesting that hormonal agents may act both via receptor and non-receptor binding mechanisms.     

Analysis of Ki‐67 expression with neoadjuvant anastrozole or tamoxifen in patients receiving goserelin for premenopausal breast cancer

BACKGROUND:

The increasing costs associated with large‐scale adjuvant trials mean that the prognostic value of biologic markers is increasingly important. The expression of nuclear antigen Ki‐67, a marker of cell proliferation, has been correlated with treatment efficacy and is being investigated for its value as a predictive marker of therapeutic response. In the current study, the authors explored correlations between Ki‐67 expression and tumor response, estrogen receptor (ER) status, progesterone receptor (PgR) status, and histopathologic response from the STAGE study (S_ tudy of T_ amoxifen or A_ rimidex, combined with G_ oserelin acetate to compare E_ fficacy and safety).

METHODS:

In a phase 3, double‐blind, randomized trial (National Clinical Trials identifier NCT00605267), premenopausal women with ER‐positive, early stage breast cancer received either anastrozole plus goserelin or tamoxifen plus goserelin for 24 weeks before surgery. The Ki‐67 index, hormone receptor (ER and PgR) status, and histopathologic responses were determined from histopathologic samples that were obtained from core‐needle biopsies at baseline and at surgery. Tumor response was determined by using magnetic resonance imaging or computed tomography.

RESULTS:

In total, 197 patients were randomized to receive either anastrozole plus goserelin (n = 98) or tamoxifen plus goserelin (n = 99). The best overall tumor response was better for the anastrozole group compared with the tamoxifen group both among patients who had a baseline Ki‐67 index ≥20% and among those who had a baseline Ki‐67 index <20%. There was no apparent correlation between baseline ER status and the Ki‐67 index in either group. Positive PgR status was reduced from baseline to week 24 in the anastrozole group.

CONCLUSIONS:

In premenopausal women with ER‐positive breast cancer, anastrozole produced a greater best overall tumor response compared with tamoxifen regardless of the baseline Ki‐67 index. Cancer 2013. © 2012 American Cancer Society.     

HYAL1 overexpression is correlated with the malignant behavior of human breast cancer

Extracellular matrix (ECM) is closely correlated with tumor cell growth, proliferation, metastasis and angiogenesis, etc. Hyaluronic acid (HA) is a component of the ECM, and hyaluronidase (HAase) is a HA‐degrading endoglycosidase. Levels of HAase are elevated in many cancers. Hyaluronidase‐1 (HYAL1) is the major tumor‐derived HAase. In this study, we detected HYAL1 expression levels in breast cancer cells and tissues, and measured the amount HAase activity in breast cancer cells. Compared with nonmalignant breast cell line HBL‐100 and normal breast tissues, HYAL1 were overexpressed in breast cancer cell lines MDA‐MB‐231, MCF‐7, invasive duct cancer tissues and metastatic lymph nodes, respectively. Accordingly, the amount HAase activity in MDA‐MB‐231 and MCF‐7 was higher than that in HBL‐100. In addition, knockdown of HYAL1 expression in MDA‐MB‐231 and MCF‐7 cells resulted in decreased cell growth, adhesion, invasion and angiogenesis potential. Meantime, the HYAL1 knockdown markedly inhibited breast cancer cell xenograft tumor growth and microvessel density. Further studies showed that the HYAL1, HYAL2 and HA were elevated in breast cancer, and HYAL1 could downregulate HA expression. In conclusion, HYAL1 may be a potential prognostic marker and therapeutic target in breast cancer.     

A novel role for flotillin‐1 in H‐Ras‐regulated breast cancer aggressiveness

Elevated expression and aberrant activation of Ras have been implicated in breast cancer aggressiveness. H‐Ras, but not N‐Ras, induces breast cell invasion. A crucial link between lipid rafts and H‐Ras function has been suggested. This study sought to identify the lipid raft protein(s) responsible for H‐Ras‐induced tumorigenicity and invasiveness of breast cancer. We conducted a comparative proteomic analysis of lipid raft proteins from invasive MCF10A human breast epithelial cells engineered to express active H‐Ras and non‐invasive cells expressing active N‐Ras. Here, we identified a lipid raft protein flotillin‐1 as an important regulator of H‐Ras activation and breast cell invasion. Flotillin‐1 was required for epidermal growth factor‐induced activation of H‐Ras, but not that of N‐Ras, in MDA‐MB‐231 triple‐negative breast cancer (TNBC) cells. Flotillin‐1 knockdown inhibited the invasiveness of MDA‐MB‐231 and Hs578T TNBC cells in vitro and in vivo. In xenograft mouse tumor models of these TNBC cell lines, we showed that flotillin‐1 played a critical role in tumor growth. Using human breast cancer samples, we provided clinical evidence for the metastatic potential of flotillin‐1. Membrane staining of flotillin‐1 was positively correlated with metastatic spread (p = 0.013) and inversely correlated with patient disease‐free survival rates (p = 0.005). Expression of flotillin‐1 was associated with H‐Ras in breast cancer, especially in TNBC (p < 0.001). Our findings provide insight into the molecular basis of Ras isoform‐specific interplay with flotillin‐1, leading to tumorigenicity and aggressiveness of breast cancer.     

Lack of G protein-coupled estrogen receptor (GPER) in the plasma membrane is associated with excellent long-term prognosis in breast cancer

G protein-coupled estrogen receptor (GPER), or GPR30, is a membrane receptor reported to mediate non-genomic estrogen responses. Tamoxifen is a partial agonist at GPER in vitro. Here, we investigated if GPER expression is prognostic in primary breast cancer, if the receptor is treatment-predictive for adjuvant tamoxifen, and if receptor subcellular localization has any impact on the prognostic value. Total and plasma membrane (PM) GPER expression was analyzed by immunohistochemistry in breast tumors from 742 postmenopausal lymph node-negative patients subsequently randomized for tamoxifen treatment for 2–5 years versus no systemic treatment, regardless of estrogen receptor (ER) status, and with a median follow-up of 17 years for patients free of event. PM GPER expression was a strong independent prognostic factor for poor prognosis in breast cancer without treatment-predictive information for tamoxifen. In the tamoxifen-treated ER-positive and progesterone receptor (PgR)-positive patient subgroup, the absence of PM GPER (53 % of all ER-positive tumors) predicted 91 % 20-year distant disease-free survival, compared to 73 % in the presence of GPER (p = 0.001). Total GPER expression showed positive correlations with ER and PgR and negative correlation with histological grade, but the correlations were biphasic. On the other hand, PM GPER expression showed strong negative correlations with ER and PgR, and strong positive correlation with HER2 overexpression and high histological grade. GPER overexpression and PM localization are critical events in breast cancer progression, and lack of GPER in the PM is associated with excellent long-term prognosis in ER-positive and PgR-positive tamoxifen-treated primary breast cancer.     

五味子对乳腺癌细胞抑制作用的体外研究

目的:评估中药五味子抗癌有效成分木酚素及其代谢产物对雌激素受体阳性以及阴性的乳腺癌细胞株的体外作用,并评价五味子对于乳腺癌的体外杀伤作用。方法:利用ATP 生物荧光药物敏感性检测技术(ATP-TCA),检测五味子木酚素对50例乳腺癌的体外杀伤作用,并检测不同浓度五味子木酚素及其代谢物（END、ENL）对于ER（＋）的MCF-7、T47D和ER（－）的MDA-MB-231、MDA-MB-435细胞株的杀伤作用。评价五味子的体外作用有效率及其与雌激素受体表型是否相关。结果:五味子对乳腺癌患者的乳腺癌细胞具有明显的体外杀伤作用,体外有效率为34.0%(17/50);五味子木酚素以浓度依赖的方式,显著降低乳腺癌细胞株MCF-7、T47D、MDA-MB-435、MDA-MB-231的存活率,且该抑制作用和细胞雌激素受体的关系并不明显（P＞0.05）,五味子木酚素在较低浓度（0.1-30μmol/L）下对雌激素受体阳性乳腺癌细胞株MCF-7、T47D表现出促进增殖的作用,当浓度提高至100μmol/L后,五味子木酚素对MCF-7、T47D增殖表现出显著的抑制作用,并呈剂量-效应关系。木酚素的低浓度促进乳腺癌细胞增殖作用在雌激素受体阴性乳腺癌细胞株MDA-MB-435、MDA-MB-231中并不明显,当浓度提高至100μmol/L后,五味子木酚素对MDA-MB-435、MDA-MB-231增殖表现出显著的抑制作用,并呈剂量-效应关系。ENL、END(3-1000μmol/L)在体外对乳腺癌细胞株存在显著抑制作用（P＜0.05）,并有剂量依赖效应,未发现其与细胞雌激素受体表型有关联（P＞0.05）。木酚素在较低浓度区间（0.1-30μmol/L）促进ER(＋)细胞株的增殖,但对ER(－)细胞株作用不显著。结论:五味子对乳腺癌细胞系以及乳腺癌患者细胞均具有较强的杀伤作用,值得进一步临床研究和应用。