Human MCF-7 Breast Cancer Xenograft Research Articles

Scandenolone from Cudrania tricuspidata fruit extract suppresses the viability of breast cancer cells (MCF-7) in vitro and in vivo

Scandenolone, an isoflavone, has shown anti-cancer potential. In this study, we extracted scandenolone from Cudrania tricuspidata fruit and evaluated its anti-breast cancer effects as well as toxicity in cell and animal models. In cell model, scandenolone suppressed the breast cancer MCF-7 cells viability, ceased mitotic cell cycle, decreased mitochondrial membrane potential, up-regulated cleaved caspase-3 and promoted the phosphorylation of p53. Additionally, this isoflavone promoted cell apoptosis and induced a sustained activation of the phosphorylation of p38 and ERK, but not JNK and Akt. The effects were further verified in a human MCF-7 breast cancer xenograft model, where scandenolone efficiently suppressed the cancer growth and increased apoptotic cells in tumor tissue. However scandenolone has also shown certain toxicity to normal hepatocytes and breast epithelial cells. It could be concluded that scandenolone suppressed the growth of breast cancer cells, but its toxicity towards normal cells might limit its potential clinical use.

Efficacy and tolerability of AFPep, a cyclic peptide with anti-breast cancer properties

PurposeThe purpose of this study is to assess the efficacy and safety profile of AFPep, a 9-amino acid cyclic peptide prior to its entry into pre-clinical toxicology analyses en route to clinical trials. MethodsAFPep was assessed for anti-estrogenic activity in a mouse uterine growth assay and for breast cancer therapeutic efficacy in a human tumor xenograft model in mice. AFPep was assessed for tolerability in a variety of in vivo models, notably including assessment for effects on rat liver and human hepatocellular carcinoma cell lines and xenografts. ResultsAFPep arrests the growth of human MCF-7 breast cancer xenografts, inhibits the estrogen-induced growth of mouse uteri, and does not affect liver growth nor stimulate growth of human hepatocellular carcinoma cell lines when growing in vitro or as xenografts in vivo. AFPep is well tolerated in mice, rats, dogs, and primates. ConclusionsAFPep is effective for the treatment of ER-positive breast cancer and exhibits a therapeutic index that is substantially wider than that for drugs currently in clinical use. The data emphasize the importance of pursuing pre-clinical toxicology studies with the intent to enter clinical trials.

Determination of clinically therapeutic endoxifen concentrations based on efficacy from human MCF7 breast cancer xenografts

Tamoxifen is a widely prescribed adjuvant anti-estrogen agent for estrogen receptor-positive breast cancer. Tamoxifen is known to undergo CYP2D6-mediated bioactivation to the active metabolite endoxifen. Endoxifen concentrations exhibit high interindividual variability, contributing to either sub-optimal tamoxifen efficacy or side effects in subsets of patients. However, the relationship between endoxifen exposure and tumor growth inhibition has not been well-characterized and little is known regarding the optimal in vivo endoxifen plasma level required for tumor inhibition. Pharmacokinetics-Pharmacodynamics (PK-PD) modeling was carried out to characterize the relationship between endoxifen concentration and tumor growth inhibition (TGI) in dose-ranging experiments in the human MCF7 xenograft bearing mouse model. Subsequently, simulations using human PK were used to determine the efficacious clinically relevant endoxifen concentration required to produce optimal tumor suppression. Based on the PK-PD model and simulations using clinical PK/concentration data of endoxifen, C stasis (100 % TGI) is observed at 53 nM, a concentration attained by many tamoxifen-treated patients. Importantly, PK-PD simulations indicate that mean steady-state levels observed in CYP2D6 extensive metabolizers are expected to result in optimal tumor suppression while mean concentrations observed in poor metabolizers are predicted to result in suboptimal TGI. Our study is the first to characterize the in vivo PK-PD relationship for endoxifen where clinically observed endoxifen concentrations are associated, in an exposure-dependent manner, with % TGI measured in a xenograft model. It is anticipated that endoxifen concentration achieved in individual patients is the limiting factor for achieving optimal tumor growth suppression.

Anti-breast cancer potential of daidzein in rodents

AimsThis study was carried out to explore anti-breast cancer potential of isoflavone daidzein or its related compounds using appropriate animal models and their anti-tumor mechanism. Main methodsDaidzein or its major metabolite equol at a dose molar equivalent to tamoxifen [1.0mg (2.7μmol)/kg or 10mg (27μmol)/kg/day] was treated orally to rats bearing 7,12-dimethylbenz(a)anthracene (DMBA)-induced mammary tumors or ovariectomized athymic nude mice implanted with human MCF-7 breast cancer xenograft and an estrogen pellet. The growth of tumors was monitored for several weeks after the treatment. The cell-cycle and apoptotic stages in mammary tumors collected from rats were analyzed by flow cytometry. Immunohistochemistry analysis was also used to determine the expression of caspase-3. Key findingsOral treatment with daidzein or equol at a human equivalent dose suppressed the growth of both DMBA-induced mammary tumors and human MCF-7 breast cancer xenografts in rodents, the inhibitory activity being superior to that of genistein or tamoxifen. Strong apoptosis induced by daidzein or equol contributes to the anti-tumor potential. SignificanceDaidzein and its metabolite equol showed the potential of inhibiting the growth of mammary tumors in rodents. Daidzein or equol could be used as a core structure to design new drugs for breast cancer therapy. Our results indicate that consumption of daidzein may protect against breast cancer.

Abstract 4528: Genotoxic and estrogenic properties of new antiestrogens

Abstract Long-term administration of tamoxifen (TAM) to breast cancer patients and women at high risk of developing this disease gives serious side effects, including endometrial cancer. These side-effects are due to the DNA damaging and/or estrogenic action of the drug. Several antiestrogens have been developed in last three decades, but were dropped out from the clinical trials due to their undesirable effects on the uterus. To avoid this serious side-effect, we have synthesized a new triphenylethylene antiestrogen, E-3-{4-[(E)-4-chloro-1-(4-hydroxyphenyl)-2-phenylbut-1-enyl]-phenyl} acrylic acid (SS1020) and a new benzopyran antiestrogen, 2E-3-{4-[(7-hydroxy-2-oxo-3-phenyl-2H-chromen-4-yl)-methyl]-phenyl}-acrylic acid (SS5020). SS1020 and SS5020 had antitumor potential much higher than that of TAM or other antiestrogens at the human equivalent doses (TAM 0.3-1.0 mg/kg/day), against 7,12-dimethylbenz(a)anthracene-induced mammary tumors in rats or human MCF-7 breast cancer xenograft implanted into athymic nude mice. To evaluate their genotoxic activity, the capability of forming hepatic DNA adducts in rats was determined. When rats were treated orally at a dose molar equivalent to TAM (20 mg/kg/day), a high level (∼1 adduct/105 nucleotides) of DNA adducts was detected in TAM-treated rats whereas no DNA adducts were observed in rats treated with SS1020 or SS5020. To evaluate the estrogenic potential, the uterotrophic activity of our compounds was determined in ovariectomized (OVX) rats at a dose molar equivalent to TAM (10 mg/kg/day), which is 30 times higher than the human equivalent dose of TAM. TAM had high uterotrophic activity while SS1020 and SS5020 did not present significant uterotrophic activity. Therefore, SS1020 and SS5020, lacking estrogenic and genotoxic actions, are expected not to induce reproductive cancers. Interestingly, the antitumor activities of several antiestrogens examined were, rather, increased significantly to the lowering uterotrophic activity evaluated with OVX-rats, but not to their antiproliferative activities against cultured estrogen receptor positive human MCF-7 breast cancer cells. The use of uterotrophic assay, not antiproliferative assay, may be a suitable screening system to exploit antiestrogen alternatives. Non-genotoxic and non-estrogenic SS1020 and SS5020, having strong antitumor potency superior to that of TAM, could be safer alternatives for breast cancer therapy and prevention. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4528. doi:10.1158/1538-7445.AM2011-4528

Anti‐breast cancer potential of SS1020, a novel antiestrogen lacking estrogenic and genotoxic actions

Long-term treatment with tamoxifen (TAM) increases the risk of developing endometrial cancer in women. Several antiestrogens developed in last decades have been discontinued from clinical testing because of their undesirable effects on the uterus. To avoid such serious side-effect while increasing the drug's anti-breast cancer potential, new triphenylethylene antiestrogens, 2E-3-{4-[(E)-4-chloro-1-(4-hydroxyphenyl)-2-phenylbut-1-enyl]-phenyl} acrylic acid (SS1020) and 2E-3-{4-[(Z)-4-chloro-1,2-diphenylbut-1-enyl]phenyl}acrylic acid (SS1010), were designed as safer alternatives. Unlike TAM, SS1020 does not present significant uterotrophic potential in rats; in contrast, SS1010, a compound removing a 4-OH moiety from SS1020, represented weak uterotrophic activity. The structurally related compounds 4-hydroxytamoxifen, toremifene, ospemifene, raloxifene (RAL) and GW5638 all have uterotrophic activity. In addition, SS1020 and SS1010 exhibit no genotoxic activity to damage hepatic DNA in rats. Therefore, SS1020 was selected as a safer antiestrogen candidate and used for evaluating the antitumor potential in animals. At the human equivalent doses of TAM, SS1020 had antitumor potential much higher than that of TAM, RAL and GW5638 against 7,12-dimethylbenz(a)anthracene-induced mammary carcinoma in rats. The growth of human MCF-7 breast cancer xenograft implanted into athymic nude mice was also effectively suppressed by SS1020. SS1020, lacking estrogenic and genotoxic actions and having strong antitumor potency superior to that of TAM and RAL, could be a safer alternative for breast cancer therapy and prevention.

Abstract 4617: Novel antiestrogens, SS1020 and SS5020, for breast cancer therapy and prevention

Abstract Tamoxifen (TAM) is widely used as a first-line endocrine therapy for breast cancer patients and as a prophylactic agent for women at high risk of developing this disease. Long-term administration of TAM has serious side effects, including endometrial cancer. These side-effects are due to the DNA damaging and/or estrogenic action of the drug. Raloxifene (RAL) approved as a chemopreventive agent for postmenopausal women at high risk for invasive breast cancer retains an estrogenic action. The poor bioavailability of RAL requires high doses to obtain an efficacy equivalent to that achieved with TAM. Several other antiestrogens developed were dropped out from the clinical trials due to their undesirable effects on the uterus. Therefore, development of new antiestrogen alternatives, but free of genotoxic and estrogenic potential, having significant antitumor potential beyond TAM and RAL is urgently required. SS1020 and SS5020 were developed as a new triphenylethylene antiestrogen and benzopyran antiestrogen, respectively, in our laboratory. Although TAM is a hepatic carcinogen and produces a high level of DNA damage in rats, both SS1020 and SS5020 did not produce such DNA damage. Unlike TAM and RAL, SS1020 and SS5020 had no detectable uterotrophic activity in OVX-rats treated even with a high dose (10 mg/kg). These indicate that SS1020 and SS5020 are free of genotoxic and estrogenic activities. The antitumor potential of SS1020 or SS5020 against 7,12-dimethyl-benz(a)anthracene-induced mammary carcinoma in rats and human MCF-7 breast cancer xenograft in athymic nude mice was superior to that of TAM and RAL. SS1020 has a much higher bioavailability than RAL, endowing it with higher antitumor potential than RAL. In addition, the development of estrogen-induced mammary tumor in rats was completed inhibited by dietary intake of SS1020, indicating that this compound has preventive potential. Taken together, SS1020 and SS5020 lacking genotoxic and estrogenic actions have anti-breast cancer activity superior to that of TAM and RAL. Both SS1020 and SS5020 are safer and more effective antiestrogen candidates for breast cancer therapy and prevention. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4617.

A New Safer and More Effective Triphenylethylene Antiestrogen (SS1020) for the Treatment and Prevention of Breast Cancer.

Abstract Background: Tamoxifen (TAM) is widely used as a first-line endocrine therapy for breast cancer patients and as a prophylactic agent for women at high risk of developing this disease. Besides the significant benefit, long-term administration of TAM has serious side effects, including endometrial cancer. These side-effects are due to the DNA damaging and/or estrogenic action of the drug. Raloxifene (RAL) approved as a chemopreventive agent for postmenopausal women at high risk for invasive breast cancer retains an estrogenic action. RAL has a poor bioavailability. This makes it difficult to achieve adequate bioavailability by oral administration in humans. High doses are required to obtain an efficacy quivalent to that achieved with TAM. Several other antiestrogens were dropped out from the clinical trials due to their undesirable effects on the uterus. Therefore, development of new antiestrogen alternatives, but free of genotoxic and estrogenic potential, having significant antitumor potential beyond TAM and RAL is urgently required for breast cancer therapy and prevention.Results: SS1020 was developed as a new triphenylethylene antiestrogen in our laboratory. Although TAM is a hepatic carcinogen and produces a high level of DNA damage in rats, SS1020 did not produce such DNA damage. Unlike TAM and RAL, SS1020 had no detectable uterotrophic activity in OVX-rats even treated with a high dose (10 mg/kg). These indicate that SS1020 is free of genotoxic and estrogenic activities. The antitumor potential of SS1020 against 7,12-dimethyl-benz(a)anthracene (DMBA)-induced mammary carcinoma in rats and human MCF-7 breast cancer xenograft in athymic nude mice was superior to that of TAM and RAL. In addition, the development of estrogen-induced mammary tumor in rats was completed inhibited by dietary intake of SS1020, indicating that this compound has preventive potential. The bioavailability of SS1020 was approximately 35 times higher than that of RAL. The maximum blood concentration (493 ng/ml serum) of SS1020 was observed at 2 hour after the oral treatment while that of RAL (15.6 ng/ml) was at 6 hours, indicating that SS1020 is absorbed rapidly into the body. SS1020 has a much higher bioavailability than RAL, endowing it with higher antitumor potential than RAL.Conclusion: Taken together, SS1020 lacking genotoxic and estrogenic actions has anti-breast cancer activity superior to that of TAM and RAL and has a preventive potential. SS1020 is a safer and more effective antiestrogen candidate for breast cancer therapy and prevention. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 4085.

Dietary lariciresinol attenuates mammary tumor growth and reduces blood vessel density in human MCF‐7 breast cancer xenografts and carcinogen‐induced mammary tumors in rats

Lariciresinol is a dietary lignan that accounts for a significant portion of the total phytoestrogen intake from Western foods. Recent epidemiological studies suggest that high dietary intake of lignans and lariciresinol is associated with reduced breast cancer risk. However, no causal relationship between lariciresinol intake and breast cancer development has been established. In this study, we investigated for the first time the effects and possible mechanisms of action of lariciresinol on hormone responsive mammary cancer in vivo in dimethylbenz[a]anthracene induced mammary cancer in rats, and in human MCF-7 breast cancer xenografts in athymic mice. For tumor bearing rats, lariciresinol (3 or 15 mg/kg of body weight) or vehicle was administered p.o. daily for 9 weeks. For E2-maintained ovariectomized athymic mice bearing orthotopic MCF-7 tumors, control diet (AIN-93G) or lariciresinol containing diet (AIN-93G supplemented with 20 or 100 mg of lariciresinol/kg of diet) was administered for 5 weeks. In both models, lariciresinol administration inhibited the tumor growth and tumor angiogenesis. In MCF-7 cells, enterolactone significantly inhibited the E2-stimulated VEGF secretion. Moreover, in MCF-7 xenografts, lariciresinol administration enhanced tumor cell apoptosis and increased estrogen receptor beta expression. Lariciresinol and its further metabolites secoisolariciresinol, enterodiol and enterolactone were found in serum of both rats and athymic mice confirming a similar lignan metabolism pattern as in humans. These findings indicate conceivable importance of dietary lignan lariciresinol in inhibition of breast cancer development.

Colony-Stimulating Factor-1 Antibody Reverses Chemoresistance in Human MCF-7 Breast Cancer Xenografts

Overexpression of colony-stimulating factor-1 (CSF-1) and its receptor in breast cancer is correlated with poor prognosis. Based on the hypothesis that blockade of CSF-1 would be beneficial in breast cancer treatment, we developed a murinized, polyethylene glycol-linked antigen-binding fragment (Fab) against mouse (host) CSF-1 (anti-CSF-1 Fab). Mice bearing human, chemoresistant MCF-7 breast cancer xenografts were treated with combination chemotherapy (CMF: cyclophosphamide, methotrexate, 5-fluorouracil; cycled twice i.p.), anti-CSF-1 Fab (i.p., cycled every 3 days for 14 days), combined CMF and anti-CSF-1 Fab, or with Ringer's solution as a control. Anti-CSF-1 Fab alone suppressed tissue CSF-1 and retarded tumor growth by 40%. Importantly, in combination with CMF, anti-CSF-1 Fab reversed chemoresistance of MCF-7 xenografts, suppressing tumor development by 56%, down-regulating expression of the chemoresistance genes breast cancer-related protein, multidrug resistance gene 1, and glucosylceramide synthase, and prolonging survival significantly. Combined treatment also reduced angiogenesis and macrophage recruitment and down-regulated tumor matrix metalloproteinase-2 (MMP-2) and MMP-12 expression. These studies support the paradigm of CSF-1 blockade in the treatment of solid tumors and show that anti-CSF-1 antibodies are potential therapeutic agents for the treatment of mammary cancer.

External Imaging of CCND1, MYC, and KRAS Oncogene mRNAs with Tumor‐Targeted Radionuclide‐PNA‐Peptide Chimeras

In 2005, breast cancer will kill approximately 40,410 women in the U.S., and pancreatic cancer will kill approximately 31,800 men and women in the U.S. Clinical examination and mammography, the currently accepted breast cancer screening methods, miss almost half of breast cancers in women younger than 40 years, approximately one-quarter of cancers in women aged 40-49 years, and one-fifth of cancers in women over 50 years old. Pancreatic cancer progresses rapidly, with only 1% of patients surviving more than 5 years after diagnosis. However, if the disease is diagnosed when it is localized, the 5-year survival is approximately 20%. It would be beneficial to detect breast cancer and pancreatic cancer at the earliest possible stage, when multimodal therapy with surgery, radiotherapy, and chemotherapy have the greatest chance of prolonging survival. Human estrogen receptor-positive breast cancer cells typically display elevated levels of Myc protein due to overexpression of MYC mRNA, elevated cyclin D1 protein due to overexpression of CCND1 mRNA, and elevated insulin-like growth factor 1 receptor (IGF1R) due to overexpression of IGF1R mRNA. We hypothesized that scintigraphic detection of MYC or CCND1 peptide nucleic acid (PNA) probes with an IGF1 peptide loop on the C-terminus, and a Tc-99m-chelator peptide on the N-terminus, could measure levels of MYC or CCND1 mRNA noninvasively in human IGF1R-overexpressing MCF7 breast cancer xenografts in immunocompromised mice. Similarly, human pancreatic cancer cells typically display elevated levels of KRAS mRNA and elevated IGF1R. Hence, we also hypothesized that a KRAS Tc-99m-chelator PNA-peptide probe could detect overexpression of KRAS mRNA in pancreatic cancer xenografts by scintigraphic imaging, or by positron emission tomography (PET) with a KRAS Cu-64-chelator PNA-peptide. Human MCF7 breast cancer xenografts in immunocompromised mice were imaged scintigraphically 4-24 h after tail-vein administration of MYC or CCND1 Tc-99m-chelator PNA-peptides, but not after administration of mismatch controls. Similarly, human Panc-1 pancreatic cancer cells xenografts were imaged scintigraphically 4 and 24 h after tail-vein administration of a KRAS Tc-99m-chelator PNA-peptide, and AsPC1 xenografts were imaged by PET 4 and 24 h after tail-vein adminstration of a KRAS Cu-64-chelator PNA-peptide. The radioprobes distributed normally to the kidneys, livers, tumors, and other tissues. External molecular imaging of oncogene mRNAs in solid tumors with radiolabel-PNA-peptide chimeras might in the future provide additional genetic characterization of pre-invasive and invasive breast cancers.

Suppression of breast cancer by chemical modulation of vulnerable zinc fingers in estrogen receptor.

Current antiestrogen therapy for breast cancer is limited by the mixed estrogenic and antiestrogenic activity of selective estrogen receptor modulators. Here we show that the function of zinc fingers in the estrogen receptor DNA-binding domain (DBD) is susceptible to chemical inhibition by electrophilic disulfide benzamide and benzisothiazolone derivatives, which selectively block binding of the estrogen receptor to its responsive element and subsequent transcription. These compounds also significantly inhibit estrogen-stimulated cell proliferation, markedly reduce tumor mass in nude mice bearing human MCF-7 breast cancer xenografts, and interfere with cell-cycle and apoptosis regulatory gene expression. Functional assays and computational analysis support a molecular mechanism whereby electrophilic agents preferentially disrupt the vulnerable C-terminal zinc finger, thus suppressing estrogen receptor-mediated breast carcinoma progression. Our results provide the proof of principle for a new strategy to inhibit breast cancer at the level of DNA binding, rather than the classical antagonism of estrogen binding.

Growth and fatty acid metabolism of human breast cancer (MCF-7) xenografts in nude rats: impact of constant light-induced nocturnal melatonin suppression.

The nocturnal melatonin (MLT) surge is a relevant oncostatic signal for a variety of experimental malignancies. Population studies support the hypothesis that exposure to light at night may represent a new risk factor for breast cancer possibly through the suppression of pineal MLT production and/or circadian disruption. We tested the ability of constant light exposure to suppress MLT production in female nude rats and stimulate the growth of tissue-isolated MCF-7 human breast cancer xenografts via increased tumor linoleic acid (LA) metabolism. Rats maintained on an alternating light/dark cycle (L:D group) exhibited a robust circadian MLT rhythm that was abolished following constant light exposure. During the exposure of animals bearing tissue-isolated human MCF-7 breast cancer xenografts to constant light, the rate of tumor growth markedly increased relative to the L:D group. Tumor LA uptake and its metabolism to the mitogen 13-hydroxyoctadecadienoic acid (13-HODE) were also substantially higher under constant light conditions. This is the first biological evidence for a potential link between constant light exposure and increased human breast oncogenesis involving MLT suppression and stimulation of tumor LA metabolism.

The novel anti-oestrogen idoxifene inhibits the growth of human MCF-7 breast cancer xenografts and reduces the frequency of acquired anti-oestrogen resistance.

The effect of idoxifene, a novel anti-oestrogen with less agonist activity than tamoxifen, was compared with that of tamoxifen on the growth of hormone-dependent MCF-7 breast cancer xenografts. Forty tumours were established with oestradiol support in ovariectomized athymic mice, allowed to grow to a median volume of 420 mm3 and then continued with oestradiol, no support, tamoxifen or idoxifene delivered by 1.5-cm silastic capsule. Tumour regression occurred with both anti-oestrogens, although maximum regression was observed following oestradiol withdrawal alone. While prolonged anti-oestrogen therapy was associated with static growth, tumour volumes were significantly lower with idoxifene (P=0.01). After 6 months, 0/10 idoxifene-treated tumours developed acquired resistance compared with 3/10 tumours treated with tamoxifen. In separate experiments, 94 animals were treated initially with oestradiol, tamoxifen, idoxifene or placebo following implantation with 1-mm3 pieces of either wild-type (WT) or tamoxifen-resistant (TR) MCF-7 tumour. After 4 months, only 1/11 WT tumours became established with idoxifene compared with 4/11 with tamoxifen, 8/12 with oestradiol and 0/12 with placebo. Likewise, fewer TR tumours were supported by idoxifene (3/12) than by tamoxifen (8/12) or oestrogen (11/12). These data indicate that, compared with tamoxifen, idoxifene shows reduced growth support of MCF-7 xenografts and may share only partial cross-resistance. Furthermore, the development of acquired anti-oestrogen resistance may be reduced during long-term idoxifene therapy. The drug's reduced agonist activity may, in part, explain these observations and indicate a preferable biochemical profile for breast cancer treatment.