Combined paclitaxel and cetuximab achieved a major response on the skin metastases of a patient with epidermal growth factor receptor-positive, estrogen receptor-negative, progesterone receptor-negative and human epidermal growth factor receptor-2-negative (triple-negative) breast cancer

The epidermal growth factor receptor, a transmembrane receptor tyrosine kinase of the erbB family, is expressed in 15-30% of all breast cancers. Anti-epidermal growth factor receptor agent cetuximab is an IgG1 chimeric monoclonal antibody with a potent antitumor activity. Cetuximab competes with ligand binding to the epidermal growth factor receptor ectodomain, resulting in an efficient blockade of tumor-promoting downstream signaling pathways. Large clinical studies recently demonstrated cetuximab synergy with radiotherapy and chemotherapy agent irinotecan. Studies in human breast cancer xenografts showed cetuximab synergy with paclitaxel, a potent mitosis spindle-cell stabilizer. In this report, combined paclitaxel and cetuximab achieved a major reduction of the skin metastases of a heavily pretreated patient with epidermal growth factor receptor-positive, estrogen receptor-negative, progesterone receptor-negative and human epidermal growth factor receptor-2-negative (triple-negative) invasive ductal breast carcinoma. Treatment was well-tolerated overall and response was not correlated with the appearance of major cetuximab-induced acneiform rash.     

Xenoestrogens down-regulate aryl-hydrocarbon receptor nuclear translocator 2 mRNA expression in human breast cancer cells via an estrogen receptor alpha-dependent mechanism

Environmental chemicals with estrogenic activity, known as xenoestrogens, may cause impaired reproductive development and endocrine-related cancers in humans by disrupting endocrine functions. Aryl-hydrocarbon receptor nuclear translocator 2 (ARNT2) is believed to play important roles in a variety of physiological processes, including estrogen signaling pathways, that may be involved in the pathogenesis and therapeutic responses of endocrine-related cancers. However, much of the underlying mechanism remains unknown. In this study, we investigated whether ARNT2 expression is regulated by a range of representative xenoestrogens in human cancer cell lines. Bisphenol A (BPA), benzyl butyl phthalate (BBP), and 1,1,1-trichloro-2,2-bis(2-chlorophenyl-4-chlorophenyl)ethane (o,p′-DDT) were found to be estrogenic toward BG1Luc4E2 cells by an E-CALUX bioassay. ARNT2 expression was downregulated by BPA, BBP, and o,p′-DDT in a dose-dependent manner in estrogen receptor 1 (ESR1)-positive MCF-7 and BG1Luc4E2 cells, but not in estrogen receptor-negative LNCaP cells. The reduction in ARNT2 expression in cells treated with the xenoestrogens was fully recovered by the addition of a specific ESR1 antagonist, MPP. In conclusion, we have shown for the first time that ARNT2 expression is modulated by xenoestrogens by an ESR1-dependent mechanism in MCF-7 breast cancer cells.     

Anatagonism of the cytocidal activity and uptake of melphalan by tamoxifen in human breast cancer cells in vitro

The effect of the antiestrogen tamoxifen on the cytocidal activity and uptake of melphalan in human breast cancer cells was investigated. A clonogenic assay was used to obtain dose-survival curves of estrogen receptor-positive MCF-7 cells and of estrogen receptor-negative Evsa T cells following treatment with melphalan and/or tamoxifen. Isobolograms derived from these dose-survival curves were concave downward, suggesting that the drug interaction was antagonistic. The effect of tamoxifen on melphalan uptake by breast cancer cells was evaluated at steady-state conditions. Thin-layer chromatography revealed that the intracellular level of free intact melphalan (mean ± S.E.) in control cells was 6.47 ± 1.21 fmoles/cell and that in cells treated with tamoxifen was 3.60 ± 0.35 fmoles/cell; this 44% reduction in cellular melphalan was statistically significant (P = 0.006). Thus, the antagonistic cytocidal effect of melphalan and tamoxifen against breast cancer cells appeared to be due to inhibition of melphalan uptake at the steady state by the antiestrogen. Further investigation revealed that tamoxifen inhibited unidirectional melphalan influx in human breast cancer cells both by the sodium-independent system L and by the sodium-dependent system ASC. Tamoxifen also appeared to stimulate melphalan efflux from human breast cancer cells. The first-order rate constant K for melphalan efflux from control cells was 0.085 ± 0.008 and that from cells treated with tamoxifen was 0.129 ± 0.005; the difference was highly significant (P < 0.001). Therefore, the antagonistic effect of tamoxifen on the uptake and cytocidal activity of melphalan in breast cancer cells appeared to be due to inhibition of melphalan influx and stimulation of drug efflux.     

XLN306 induces apoptosis in human breast carcinoma MX-1 cells

XLN306 is a novel synthetic quinazoline derivative with potentially useful anticancer activity. In previous research, we showed that XLN306 is highly cytotoxic to many tumor cell lines. This paper reports an investigation of this cytotoxicity in a number of human carcinoma cell lines. The results show that human breast carcinoma MX-1 cells are extremely sensitive to XLN306 and that the cytotoxicity is due to dose- and time-dependent apoptosis as confirmed by DAPI stain and DNA fragmentation analysis. Both extrinsic and intrinsic pathways are involved in the apoptosis process. The findings indicate that XLN306 has apoptotic induction activity and may be useful for the management of various cancers, especially breast carcinoma.     

Anti-Cancer Effect of IN-2001 in MDA-MB-231 Human Breast Cancer

In recent years, inhibition of HDACs has emerged as a potential strategy to reverse aberrant epigenetic changes associated with cancer, and several classes of HDAC inhibitors have been found to have potent and specific anticancer activities in preclinical studies. But their precise mechanism of action has not been elucidated. In this study, a novel synthetic inhibitor of HDAC, 3-(4-dimethylamino phenyl)-N-hydroxy-2-propenamide [IN-2001] was examined for its antitumor activity and the underlying molecular mechanisms of any such activity on human breast cancer cell lines. IN-2001 effectively inhibited cellular HDAC activity (IC₅₀ = 0.585 nM) in MDA-MB-231 human breast cancer cells. IN-2001 caused a significant dose-dependent inhibition of cell proliferation in estrogen receptor (ER) negative MDA-MB-231 human breast cancer cells. Cell cycle analysis revealed that the gowth inhibitory effects of IN-2001 might be attributed to cell cycle arrest at G₀/G₁ and/or G₂/Mphase and subsequent apoptosis in human breast cancer cells. These events are accompanied by modulating several cell cycle and apoptosis regulatory genes such as CDK inhibitors p21^WAF1 and p27^KIP1 cyclin D1, and other tumor suppressor genes such as cyclin D2. Collectively, IN-2001 inhibited cell proliferation and induced apoptosis in human breast cancer cells and these findings may provide new therapeutic approaches, combination of antiestrogen together with a HDAC inhibitor, in the hormonal therapy-resistant ER-negative breast cancers. In summary, our data suggest that this histone deacetylase inhibitor, IN-2001, is a novel promising therapeutic agent with potent antitumor effects against human breast cancers.     

原癌基因Fra－1在人乳腺肿瘤组织中表达的初步研究

目的：探讨转录因子Fra－1在人乳腺良、恶性肿瘤组织中的表达及细胞内的定位。方法：采用免疫组织化学方法检测良、恶性乳腺肿瘤组织Fra－1表达及细胞定位;并分析恶性乳腺肿瘤组织Fra-1表达与乳腺癌预后指标ER、PR和HER－2表达的相关性。结果：61例良、恶性肿瘤组织都存在Fra－1的细胞核表达。在20例良性肿瘤组织中,17例（85．0％）Era－1主要定位于上皮细胞核内,3例（15．0％）可见Fra－1细胞核及细胞质共表达。而37例（90．2％）恶性肿瘤组织存在Fra－1细胞核和细胞质共表达,Fra－1在恶性肿瘤细胞质中的表达明显高于良性肿瘤（P=0．000）。恶性肿瘤Fra－1细胞质表达与ER、PR和HER－2的表达无明显相关性。结论：Fra－1蛋白的表达强度和方式与乳腺癌上皮细胞的癌变有关;它在乳腺癌细胞细胞席的滞留与乳腺癌的发生、发展具有一定的相关性。     

Estrogen-dependent regulation of Eg5 in breast cancer cells

HsEg5 (Eg5) is a kinesin required for proper execution of mitosis. Several compounds that specifically block Eg5 are in clinical development and have the potential to be used in the treatment of breast cancer. In this study, we investigated the interaction between Eg5 and estrogen receptor signaling. We observed decreased Eg5 expression after treatment of estrogen receptor-positive human breast cancer MCF-7 cells with the estrogen receptor downregulator fulvestrant. Downregulation of Eg5 expression in response to fulvestrant was also observed in another estrogen receptor-positive cell line ZR-75, but not in the estrogen receptor-negative breast cancer cell line MDA-231. Moreover, in MCF-7 cells previously arrested in the G0/G1 phase of the cell cycle by fulvestrant, addition of estrogen increased Eg5 expression. This upregulation correlated with progression through S-phase. Nevertheless, the effect of fulvestrant in Eg5 expression could not be explained solely by cell cycle arrest, because treatments that blocked cell cycle progression did not consistently decrease Eg5 expression. Pharmacological inhibition of Eg5 function, with either S-trityl-L-cysteine or monastrol, prevented growth of estrogen-treated MCF-7 cells with an IC50 of 0.46 and 29.71 micromol/l, respectively. Simultaneous inhibition of estrogen receptor function with fulvestrant increased the IC50 for S-trityl-L-cysteine to 2.30 micromol/l and for monastrol to 112.69 micromol/l. Our results suggest that pharmacological inhibition of Eg5 may be an effective treatment for estrogen receptor-positive breast cancer, even without concomitant hormonal therapy.     

Antiestrogen, trans-tamoxifen modulation of human breast cancer cell growth

To gain further insight into how estrogens modulate cell function, the effects of estrogen on cell proliferation were studied in human breast cancer cells. We examined the effects of estrogen on the proliferation of three human breast cancer cell lines that differed in their estrogen receptor contents. Ten nM estradiol markedly stimulated the proliferation of MCF-7 human breast cancer cells that contained high levels of estrogen receptor (1.15±0.03 pmole/mg protein) over that of control. In T47D cells that contained low levels of estrogen receptor (0.23±0.05 pmole/mg protein), Ten nM estrogen slightly stimulated the proliferation over that of control. MDA-MB-231 cells, that contained no detectable levels of estrogen receptors, had their growth unaffected by estrogen. These results showed their sensitivity to growth stimulation by estrogen correlated well with their estrogen receptor content. Also we examined the effect of estrogen on cellular progesterone receptor level as well as plasminogen activator activity in MCF-7 cells. Ten nM estradiol showed maximal stimulation of progesterone receptor level as well as plasminogen activator activity in MCF-7 cells. It is not clear whether these stimulations of progesterone receptor and plasminogen activator activity by estrogen are related to the estrogen stimulation of cell proliferation of MCF-7 cells. Studies with estrogen in human breast cancer cells in culture indicate that sensitivity to growth stimulation by estrogen correlates well with estrogen receptor contents.     

Activity of a chartreusin analog, elsamicin A, on breast cancer cells.

The in vitro activity of elsamicin A (ELS) was investigated compared with that of doxorubicin (DX) on two sensitive breast cancer cell lines: one estrogen receptor-positive (ER+, MCF7) and one estrogen receptor-negative (ER-, MDA-MB-231) line, and on a DX-resistant subline (MCF7DX). The activity of the two drugs was also investigated on 19 clinical breast cancer specimens from untreated patients. The drugs were tested at pharamcologically relevant concentrations, as calculated from the area under the curve for a 3 h exposure to the lethal dose producing 10% mortality (LD10) in mice, and at 10- and 100-fold concentrations. In DX-sensitive lines, a greater inhibition of RNA and DNA precursor incorporation, as well as of cell proliferation, was caused by ELS than by DX. Moreover, the antiproliferative effect was 10-fold higher in the ER+ MCF7 than in the ER- MDA-MB-231 cell line (IC50: 0.25 versus 0.21 micrograms/ml). ELS was cross-resistant to DX in the MCF7DX subline. In clinical specimens, effects on DNA precursor incorporation were more often observed for ELS than for DX at the same drug concentrations. The in vitro sensitivity to ELS was more pronounced for ER+ than for ER- tumors: minimal inhibiting concentrations of the drug were 0.1 and 3.5 micrograms/ml, respectively, in the two groups. If confirmed in a larger series of human breast tumors, these in vitro results would indicate a promising role for ELS in clinical treatment, mainly of ER+ breast cancer patients.     

DNA methylation of retinoic acid receptor beta in breast cancer and possible therapeutic role of 5-aza-2'-deoxycytidine.

The retinoic acid receptor beta (RARbeta), a putative tumor suppressor gene, has been reported to be poorly expressed in breast cancer. In this report using the methylation-specific PCR reaction we observed DNA methylation in the promoter region of RARbeta in several primary breast tumors. DNA sequence analysis showed that the positions of 5-methylcytosine in the RARbeta promoter region was almost identical to that reported previously by our laboratory for human DLD-1 colon carcinoma cells (Anti-Cancer Drugs 1998; 9: 743). Several other cancer-related genes have been also reported to be silenced by DNA methylation, including the p16 tumor suppressor gene, E-cadherin, an invasion suppressor gene and the estrogen receptor gene in breast cancer cell lines. Since breast cancer cells have several potential target genes for the DNA methylation inhibitor, 5-aza-2'-deoxycytidine (5-Aza-CdR), we investigated the in vitro antineoplastic activity of this analog on the human breast cancer cell line MDA-MB-231. We report that 5-Aza-CdR is a potent growth inhibitor and a potent cytotoxic agent against the breast carcinoma cells. These results suggest that 5-Aza-CdR may be an interesting agent to investigate in patients with breast cancer resistant to conventional chemotherapy.     

Estrogen modulation of human breast cancer cell growth

To gain further insight into how estrogens modulate cell function, the effects of estrogen on cell proliferation were studied in human breast cancer cells. We examined the effects of estrogen on the proliferation of three human breast cancer cell lines that differed in their estrogen receptor contents. Ten nM estradiol markedly stimulated the proliferation of MCF-7 human breast cancer cells that contained high levels of estrogen receptor (1.15+/-0.03 pmole/mg protein) over that of control. In T47D cells that contained low levels of estrogen receptor (0.23+/-0.05 pmole/mg protein), Ten nM estrogen slightly stimulated the proliferation over that of control. MDA-MB-231 cells, that contained no detectable levels of estrogen receptors, had their growth unaffected by estrogen. These results showed their sensitivity to growth stimulation by estrogen correlated well with their estrogen receptor content. Also we examined the effect of estrogen on cellular progesterone receptor level as well as plasminogen activator activity in MCF-7 cells. Ten nM estradiol showed maximal stimulation of progesterone receptor level as well as plasminogen activator activity in MCF-7 cells. It is not clear whether these stimulations of progesterone receptor and plasminogen activator activity by estrogen are related to the estrogen stimulation of cell proliferation of MCF-7 cells. Studies with estrogen in human breast cancer cells in culture indicate that sensitivity to growth stimulation by estrogen correlates well with estrogen receptor contents.     

Everolimus: targeted therapy on the horizon for the treatment of breast cancer

The mammalian target of rapamycin (mTOR) is a signaling kinase of the phosphatidylinositol 3-kinase/protein kinase B (also known as Akt) signaling pathway that mediates cell growth and metabolism. Dysregulation of the mTOR pathway creates a favorable environment for the development and progression of many cancers, including breast cancer, and is associated with the development of resistance to endocrine therapy and to the anti-human epidermal growth factor receptor-2 (HER2) monoclonal antibody trastuzumab. Therefore, the addition of mTOR inhibitors to conventional breast cancer therapy has the potential to enhance therapeutic efficacy and/or overcome innate or acquired resistance. Everolimus, an mTOR inhibitor with demonstrated preclinical activity against breast cancer cell lines, has been shown to reverse Akt-induced resistance to hormonal therapy and trastuzumab. Phase I-II clinical trials have demonstrated that everolimus has promising clinical activity in women with HER2-positive, HER2-negative, and estrogen receptor-positive breast cancer when combined with HER2-targeted therapy, cytotoxic chemotherapy, and hormonal therapy, respectively. Everolimus is generally well tolerated; hematologic abnormalities and stomatitis are most common adverse events when this drug is combined with cytotoxic chemotherapy. Based on these promising results, everolimus is currently under evaluation in a series of phase III Breast Cancer Trials of Oral Everolimus (BOLERO) trials of women with HER2-positive and estrogen receptor-positive breast cancer. Results of these trials will help to establish the role of everolimus in the treatment of clinically important breast cancer subtypes.     

The association between chemotherapy-induced febrile neutropenia and breast cancer subtype in Japanese patients

Background Chemotherapy-induced febrile neutropenia is a common and potentially lethal side effect; therefore, predicting febrile neutropenia development is important. Objective This study examined the risk factors for febrile neutropenia development according to breast cancer subtype among Japanese patients receiving chemotherapy. Methods This single-center retrospective study evaluated 60 outpatients who received chemotherapy for breast cancer (epirubicin plus cyclophosphamide or docetaxel plus cyclophosphamide). Their characteristics were evaluated to identify factors associated with febrile neutropenia development. Results Thirty-three patients developed febrile neutropenia and 27 patients did not. The risk of developing febrile neutropenia was significantly associated with estrogen receptor negativity (p?<?0.05). Logistic regression analysis further confirmed that estrogen receptor negativity was an independent risk factor for febrile neutropenia development (odds ratio: 4.35, 95% confidence interval: 1.05–18.0). Moreover, the highest rate of febrile neutropenia was observed in patients with hormone receptor (estrogen and/or progesterone receptor)-negative/human epidermal growth factor receptor 2-positive breast cancer. Conclusion In addition to the known risk factors for febrile neutropenia, our findings revealed that the risk of developing chemotherapy-induced febrile neutropenia is associated with the hormone receptor-negative/human epidermal growth factor receptor 2-positive subtype in Japanese patients with breast cancer.

     

Cytotoxic estrogens: anilin mustard linked 1,1,2-triphenylbut-1-enes with mammary tumor inhibiting activity

In order to develop cytotoxic estrogens with a specific effect on hormone-dependent mammary tumors, two 1,1,2-triphenylbut-1-enes with a 4-OH group at one C-1-phenyl ring and a chloro-[4] or bromo-[8] anilin mustard moiety at the other C-1-phenyl ring were synthesized. 4 and 8 exerted strong alkylating activity and an irreversible binding to the estrogen receptor. In spite of relatively low receptor affinities, both anilin mustards exhibited a better effect on a receptor-positive breast cancer cell line as well as on a hormone-dependent mammary carcinoma of the mouse than on a receptor-negative cell line and a hormone-independent mammary carcinoma. Therefore, a selective antitumor activity of 4 and 8 is likely.