Drug For Breast Cancer Therapy Research Articles

A Novel Strategy to Co-target Estrogen Receptor and Nuclear Factor κB Pathways with Hybrid Drugs for Breast Cancer Therapy.

Nearly 75% of breast tumors express estrogen receptor (ER), and will be treated with endocrine therapy, such as selective estrogen receptor modulator (SERM), tamoxifen, or aromatase inhibitors. Despite their proven success, as many as 40-50% of ER+ tumors fail to respond to endocrine therapy and eventually recur as aggressive, metastatic cancers. Therefore, preventing and/or overcoming endocrine resistance in ER+ tumors remains a major clinical challenge. Deregulation or activation of the nuclear factor κB (NFκB) pathway has been implicated in endocrine resistance and poor patient outcome in ER+ tumors. As a consequence, one option to improve on existing anti-cancer treatment regimens may be to introduce additional anti-NFκB activity to endocrine therapy drugs. Our approach was to design and test SERM-fumarate co-targeting hybrid drugs capable of simultaneously inhibiting both ER, via the SERM, raloxifene, and the NFκB pathway, via fumarate, in breast cancer cells. We find that the hybrid drugs display improved anti-NFκB pathway inhibition compared to either raloxifene or fumarate. Despite some loss in potency against the ER pathway, these hybrid drugs maintain anti-proliferative activity in ER+ breast cancer cells. Furthermore, these drugs prevent clonogenic growth and mammosphere formation of ER+ breast cancer cells. As a proof-of-principle, the simultaneous inhibition of ER and NFκB via a single bifunctional hybrid drug may represent a viable approach to improve the anti-inflammatory activity and prevent therapy resistance of ER-targeted anti-cancer drugs.

Mechanisms of the anti-tumor activity of Methyl 2-(-5-fluoro-2-hydroxyphenyl)-1 H-benzo[d]imidazole-5-carboxylate against breast cancer in vitro and in vivo.

Microtubule Targeting Agents (MTAs) induce cell death through mitotic arrest, preferentially affecting rapidly dividing cancer cells over slowly proliferating normal cells. Previously, we showed that Methyl 2-(−5-fluoro-2-hydroxyphenyl)-1H-benzo[d]imidazole-5-carboxylate (MBIC) acts as a potential MTA. In this study, we demonstrated that MBIC exhibits greater toxicity towards non-aggressive breast cancer cell-line, MCF-7 (IC50 = 0.73 ± 0.0 μM) compared to normal fibroblast cell-line, L-cells (IC50 = 59.6 ± 2.5 μM). The IC50 of MBIC against the aggressive breast cancer cell-line, MDA-MB-231 was 20.4 ± 0.2 μM. We hypothesized that the relatively high resistance of MDA-MB-231 cells to MBIC is associated with p53 mutation. We investigated p53 and three of its downstream proteins: survivin, cyclin dependent kinase (Cdk1) and cyclin B1. Following treatment with MBIC, survivin co-immunoprecipitated with caspases with higher affinity in MDA-MB-231 compared to MCF-7 cells. Furthermore, silencing survivin caused a 4.5-fold increase in sensitivity of MDA-MB-231 cells to MBIC (IC50 = 4.4 ± 0.3). In addition, 4 weeks of MBIC administration in MDA-MB-231 cells inoculated BALB/c nude mice resulted in 79.7% reduction of tumor volume compared to the untreated group with no severe sign of toxicity. Our results demonstrated MBIC has multiple anti-tumor actions and could be a potential drug in breast cancer therapy.

Sinomenine hydrochloride inhibits breast cancer metastasis by attenuating inflammation-related epithelial-mesenchymal transition and cancer stemness.

Sinomenine hydrochloride (SH) has been investigated for its anti-tumor growth effect. We have previously reported that SH inhibited breast cancer cell proliferation via MAPKs signaling. However, whether SH could inhibit tumor metastasis has not been fully explored. In this study, we found that SH suppressed the metastasis potential of breast cancer cells. The wound healing and transwell assays showed that SH inhibited the migration and invasion ability of both 4T1 and MDA-MB-231 breast cancer cells. The orthotopic mouse model of 4T1 and the experimental mouse model of MDA-MB-231-luc (MDA-MB-231 cell line expressing firefly luciferase) demonstrated that SH treatment inhibited breast cancer metastasis by inhibiting epithelial–mesenchymal transition (EMT) and cancer stem cell (CSC) properties without obvious hepatotoxicity and renal toxicity. We also found that SH decreased spleen volume and weight in both mouse models, especially in the 4T1 mouse model. IL-6, a strong inflammatory factor causing EMT, was remarkably reduced. Overall, this anti-metastasis effect of SH could be possibly caused by attenuating inflammatory reaction, which led to inhibition of EMT and CSC characteristics of breast cancer cells. This study, together with our previous one, provides more evidence of SH as a potential drug for breast cancer therapy.

Oxymatrine Promotes S-Phase Arrest and Inhibits Cell Proliferation of Human Breast Cancer Cells in Vitro through Mitochondria-Mediated Apoptosis.

Breast cancer is one of the most lethal malignancies in the world. Oxymatrine is the major effective and toxic alkaloid component which is derived from the root of Sophora flavescens AIT, a traditional Chinese medicine which is widely distributed in Asia and the Pacific Islands. In the current research study, we investigated the effects and mechanisms of action of oxymatrine on breast cancer cells. We demonstrated that the viability and single cell proliferation capability of MCF-7 and MDA-MB-231, two breast cancer cell lines which are widely used in in vitro study, were significantly suppressed in a time- and concentration-dependent manner. Furthermore, the cell cycle of breast cancer cells treated with oxymatrine was arrested at the S-phase of the cell cycle. Oxymatrine also triggered apoptosis in breast cancer cells by modulating apoptosis-related proteins, such as cleaved Caspase-3, cleaved Caspase-9 and poly(ADP-ribose)polymerase (PARP). The remarkable reduction in the ratio of Bcl-2/Bax was also observed in oxymatrine treated breast cancer cells. In conclusion, our research demonstrated that oxymatrine plays a critical role in suppressing carcinogenesis of breast cancer cells through cell cycle arrest and induction of mitochondria-mediated apoptosis, which suggests a promising application of this drug in breast cancer therapy.

Self-delivering prodrug-nanoassemblies fabricated by disulfide bond bridged oleate prodrug of docetaxel for breast cancer therapy

Breast cancer leads to high mortality of women in the world. Docetaxel (DTX) has been widely applied as one of the first-line chemotherapeutic drugs for breast cancer therapy. However, the clinical outcome of DTX is far from satisfaction due to its poor drug delivery efficiency. Herein, a novel disulfide bond bridged oleate prodrug of DTX was designed and synthesized to construct self-delivering prodrug-based nanosystem for improved anticancer efficacy of DTX. The uniquely engineered prodrug-nanoassemblies showed redox-responsive drug release, increased cellular uptake and comparable cytotoxicity against 4T1 breast cancer cells when compared with free DTX. In vivo, oleate prodrug-based nanoparticles (NPs) demonstrated significantly prolonged systemic circulation and increased accumulation in tumor site. As a result, prodrug NPs produced a notable antitumor activity in 4T1 breast cancer xenograft in BALB/c mice. This prodrug-based self-assembly and self-delivery strategy could be utilized to improve the delivery efficiency of DTX for breast cancer treatment.

Raddeanoside R13 inhibits breast cancer cell proliferation, invasion, and metastasis.

Pulsatilla chinensis is one of the 50 famous fundamental herbs used in traditional Chinese medicine. Saponins are the main components of P. chinensis. Although the anti-proliferative function of saponins has been established in plenty types of cancer, the role of saponins on tumor invasion and metastasis has not been reported, and the mechanisms of how saponins exert the anti-tumor functions are still poorly characterized. Here, we demonstrate that, in breast cancer (BC) cells, raddeanoside R13, a component of saponins extracted from P. chinensis, exhibits strong anti-proliferative and anti-metastasis ability, accompanied by cell cycle arrest, apoptosis, autophagy, and reversion of epithelial-mesenchymal transition (EMT). Raddeanoside R13 (R13) inhibits BC cell proliferation via the activation of G1/S checkpoint transitions, concomitant with a marked decrease of the positive cell cycle regulators, including cyclin D1, cyclin A, and cyclin B1. R13 induces BC cell apoptosis accompanied by the increased levels of cleaved PARP and caspase-3. R13 inhibits BC cell migration and invasion and regulates the expression of the markers of EMT, which plays a critical role in cancer cell migration and invasion. Moreover, R13 suppresses BC tumor growth and metastasis in nude mice. These data highlight the important role of R13 in BC cell proliferation and progression and suggest that R13 may be a useful drug for BC therapy.

Role of nuclear receptors in breast cancer stem cells.

The recapitulation of primary tumour heterogenity and the existence of a minor sub-population of cancer cells, capable of initiating tumour growth in xenografts on serial passages, led to the hypothesis that cancer stem cells (CSCs) exist. CSCs are present in many tumours, among which is breast cancer. Breast CSCs (BCSCs) are likely to sustain the growth of the primary tumour mass, as well as to be responsible for disease relapse and metastatic spreading. Consequently, BCSCs represent the most significant target for new drugs in breast cancer therapy. Both the hypoxic condition in BCSCs biology and pro-inflammatory cytokine network has gained increasing importance in the recent past. Breast stromal cells are crucial components of the tumours milieu and are a major source of inflammatory mediators. Recently, the anti-inflammatory role of some nuclear receptors ligands has emerged in several diseases, including breast cancer. Therefore, the use of nuclear receptors ligands may be a valid strategy to inhibit BCSCs viability and consequently breast cancer growth and disease relapse.

MiRNA oligonucleotide and sponge for miRNA-21 inhibition mediated by PEI-PLL in breast cancer therapy

MicroRNA-21 (miR-21) inhibition is a promising biological strategy for breast cancer therapy. However its application is limited by the lack of efficient miRNA inhibitor delivery systems. As a cationic polymer transfection material for nucleic acids, the poly (l-lysine)-modified polyethylenimine (PEI-PLL) copolymer combines the high transfection efficiency of polyethylenimine (PEI) and the good biodegradability of polyllysine (PLL). In this work, PEI-PLL was successfully synthesized and confirmed to transfect plasmid and oligonucleotide more effectively than PEI in MCF-7 cells (human breast cancer cells). In this regard, two kinds of miR-21 inhibitors, miR-21 sponge plasmid DNA (Sponge) and anti-miR-21 oligonucleotide (AMO), were transported into MCF-7 cells by PEI-PLL respectively. The miR-21 expression and the cellular physiology were determined post transfection. Compared with the negative control, PEI-PLL/Sponge or PEI-PLL/AMO groups exhibited lower miR-21 expression and cell viability. The anti-tumor mechanism of PEI-PLL/miR-21 inhibitors was further studied by cell cycle and western blot analyses. The results indicated that the miR-21 inhibition could induce the cell cycle arrest in G1 phase, upregulate the expression of Programmed Cell Death Protein 4 (PDCD4) and thus active the caspase-3 apoptosis pathway. Interestingly, the PEI-PLL/Sponge and PEI-PLL/AMO also sensitized the MCF-7 cells to anti-tumor drugs, doxorubicin (DOX) and cisplatin (CDDP). These results demonstrated that PEI-PLL/Sponge and PEI-PLL/AMO complexes would be two novel and promising gene delivery systems for breast cancer gene therapy based on miR-21 inhibition. Statement of SignificanceThis work was a combination of the high transfection efficiency of polyethylenimine (PEI), the good biodegradability of polyllysine (PLL) and the breast cancer-killing effect of miR-21 inhibitors. The poly (l-lysine)-modified polyethylenimine (PEI-PLL) copolymer was employed as the vector of miR-21 sponge plasmid DNA (Sponge) or anti-miR-21 oligonucleotide (AMO). PEI-PLL showed more transfection efficiency and lower cytotoxicity in human breast cancer cells than PEI. Moreover, the breast cancer cells exhibited significantly lower miR-21 expression and cell viability post transfection with sponge or AMO. Interestingly, the PEI-PLL/miR-21 inhibitor complexes also sensitized the cancer cells to anti-cancer chemotherapy drugs, doxorubicin (DOX) and cisplatin (CDDP). This synergistic effect provides a good application prospect of co-delivery miR-21 inhibitors and chemical drugs in breast cancer therapy.

Random laser in biological tissues impregnated with a fluorescent anticancer drug

We have demonstrated that chemically modified anticancer drugs can provide random laser (RL) when infiltrated in a biological tissue. A fluorescent biomarker has been covalently bound to tamoxifen, which is one of the most frequently used drugs for breast cancer therapy. The light emitted by the drug-dye composite is scattered in tissue, which acts as a gain medium. Both non-coherent and coherent RL regimes have been observed. Moreover, the analysis of power Fourier transforms of coherent RL spectra indicates that the tissues show a dominant random laser cavity length of about 18 µm, similar to the average size of single cells. These results show that RL could be obtained from other drugs, if properly marked with a fluorescent tag, which could be appealing for new forms of combined opto-chemical therapies.

Abstract 771: TLR4 activation by paclitaxel promotes breast cancer recurrence and metastasis

Abstract Background: Paclitaxel (PXL) is a widely-used drug for breast cancer therapy. Resistance, however, occurs frequently and the evasion mechanisms remain unclear. PXL is known to activate Toll-like Receptor-4 (TLR4), a major signaling receptor expressed on immune cells responding to lipopolysaccharide (LPS). LPS activation of TLR4 in the immune cells substantially enhances their migratory, invasive, proliferative, and pro-survival functions as necessary for the body defense. Since PXL is a functional LPS mimetic, we hypothesized that acquisition of such phenotype by TLR4-expressing cancer cells promotes tumor growth, metastasis, and resistance to therapy. Methods: We tested this hypothesis in two breast cancer luciferase-tagged models genetically modified to either suppress TLR4 expression in a positive line, MDA-MB-231, or overexpress it in a negative line, HCC1806. Modified cell lines and their controls were orthotopically implanted in mice followed by measuring tumor growth prior and post-PXL treatment. Incidence and burden of lymph node (LN) and lung metastases were quantified by measuring luciferase activity in respective organs. TLR4-induced inflammation was assessed by measuring cytokines in blood, tumor lysates, and metastatic organs using RT-qPCR and ELISA. Cell composition of spleens and bone marrow from control and treated mice were analyzed by FACS. TLR4-induced changes in tumor vasculature were determined by immunostaining for blood and lymphatic vessel markers. Results: TLR4 expressed in tumor cells significantly increased rate of recurrence and metastasis, an event augmented by PXL treatment. Local inflammation was also enhanced by the PXL•TLR4 axis as illustrated by a 276-fold increase in IL-6 in lysates of TLR4+ tumors from treated mice as compared with samples of isogenic tumors with depleted TLR4. Activation of this pathway also increased cytokine levels in the blood and distant organs as indicted by 3-6 fold increase in IL-4 and IL-10 in LNs and lungs. These pro-inflammatory systemic changes promoted generation of myeloid progenitors in bone marrow and spleen evident by 4-5 fold increase in Ly6C+ cell population in TLR4-overexpressing tumors compared with those lacking TLR4. Importantly, activation of the PXL•TLR4 axis induced intratumoral formation of lymphatic vessels in HCC1806 tumors absent in all other experimental groups. Conclusion: These data imply that PXL therapy activates TLR4 often overexpressed in breast cancer. Activation of this pathway substantially increases local tumor and systemic inflammation leading to generation of myeloid progenitors that can promote metastasis by inducing angiogenesis and lymphatic vessel formation, particularly inside the tumor. These findings suggest that tumor expression of TLR4 may indicate poor prognosis and response to therapy, and that blocking the TLR4 pathway may improve current anti-cancer treatments. Citation Format: Sandeep Rajput, Lisa Volk-Draper, Kelly Hall, Sophia Ran. TLR4 activation by paclitaxel promotes breast cancer recurrence and metastasis. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 771. doi:10.1158/1538-7445.AM2014-771

PEG–PCL based micelle hydrogels as oral docetaxel delivery systems for breast cancer therapy

In this study, a composite drug delivery system was developed and evaluated for oral delivery of docetaxel: docetaxel-loaded micelles in pH-responsive hydrogel (DTX-micelle–hydrogel). Docetaxel was successfully loaded in micelles with small particle size of 20 nm and high drug loading of 7.76%, which contributed to the drug absorption in the intestinal tract. The experiments of cytotoxicity on 4T1 cells demonstrated the effective antitumor activity of DTX micelles. Meanwhile, a pH-responsive hydrogel was synthesized and optimized for incorporating the docetaxel micelles. The pH-responsiveness and reversibility of the hydrogel were investigated under the pH conditions of the gastrointestinal tract. Furthermore, the DTX-micelle–hydrogel system showed much quicker diffusion of micelles in simulated intestinal fluid than in simulated gastric fluid, which was mainly caused by the change of pH value. The docetaxel released from the micelle–hydrogel system quite slowly, so it had little influence on the absorption of DTX micelles in small intestine. More important, the pharmacokinetic study revealed that the DTX-micelle–hydrogel significantly improved the oral bioavailability of docetaxel (75.6%) about 10 times compared to DTX micelles, and this increase in bioavailability was probably due to the small intestine targeting release of the pH-responsive hydrogel. Consequently, the oral DTX-micelle–hydrogel system was effective in inhibiting tumor growth in subcutaneous 4T1 breast cancer model, and decreased systemic toxicity compared with intravenous treatment. The apoptosis cells in the immunofluorescent studies and the proliferation-positive cells in the immunohistochemical studies were also consistent with the results. Therefore, the DTX-micelle–hydrogel system might be a promising candidate oral drug for breast cancer therapy.

Anti-proliferative and apoptosis-inducing effects of camptothecin-20(s)-O-(2-pyrazolyl-1)acetic ester in human breast tumor MCF-7 cells.

Camptothecin-20(s)-O-(2-pyrazolyl-1)acetic ester (CPT6) is a novel semi-synthetic analog of camptothecin. In a previous report, CPT6 possessed higher cytotoxic activity in vitro towards human breast tumor MCF-7 cells than topotecan. In this study, the antitumor activity of CPT6 on the human breast tumor MCF-7 cell line was analyzed using the MTT method. The underlying mechanism of CPT6 action was investigated by analyzing the cell cycle distribution, apoptotic proportion, changes in mitochondrial membrane potential, and intracellular Ca2+ concentration using flow cytometry. Nuclear and mitochondrial morphologies were also observed by laser scanning confocal and transmission electron microscopy. DNA damage was observed in MCF-7 cells treated with CPT6. Low-dose CPT6 had a significant cytotoxic effect and could inhibit proliferation and induce apoptosis in MCF-7 cells, possibly through cell nucleus fragmentation and DNA damage. CPT6 thus appears to display potent antitumor activity against human breast tumor MCF-7 cells via the induction of apoptosis, and may be a useful alternative drug for breast cancer therapy.

In silico study of curcumol, curcumenol, isocurcumenol, and β-sitosterol as potential inhibitors of estrogen receptor alpha of breast cancer

Background: Based on data from the Hospital Information System (HIS) in 2007, breast cancer is the top ranked diagnosed cancer in Indonesia. Estrogen receptor alpha (ERα) is associated with breast cancer because it is found in high levels in cancer tissues. Curcumol, curcumenol, isocurcumenol of white tumeric rhizomes ( Curcuma zedoaria ( Christm .) Roscoe ), and β-sitosterol from seeds of pumpkin ( Cucurbita pepo L. ) have been reported to have inhibitory activity against cancer cells. This study presents the in silico study of these compounds as inhibitors of ERα. Methods: Docking simulations are carried out in this paper to visualize molecular-level interactions between the four compounds with ERα. Docking simulations between estradiol and tamoxifen on ERα are carried out as well. Results: Docking results indicated that curcumol, curcumenol, isocurcumenol, and β-sitosterol showed inhibitory activity againts estrogen receptor alpha (ERα). The order of potency is shown consecutively by isocurcumenol, curcumol, curcumenol, and β-sitosterol with values 0.584 M, 1.36 M, 1.61 M, and 7.35 M respectively. Curcumenol and estradiol interacts with ERα through hydrogen bonds and hydrophobic interactions, whereas curcumol, isocurcumenol, β-sitosterol and tamoxifen through hydrophobic interactions in succession. Conclusion: Natural products containing all four compounds have the potential to be used as drugs or adjuvant drugs in breast cancer therapy. Keywords: β-sitosterol, breast cancer, curcumol, curcumenol, estradiol, ERα, isocurcumenol

Estrogen receptor β agonists affect growth and gene expression of human breast cancer cell lines

Expression of estrogen receptor β (ERβ) has been described to reduce growth of cancer cell lines derived from hormone-dependent tumors, like breast cancer. In this study we tested to what extent two ERβ agonists, androgen derivative 3β-Adiol and flavonoid Liquiritigenin, would affect growth and gene expression of different ERβ-positive human breast cancer cell lines. Under standard cell culture conditions, we observed 3β-Adiol to inhibit growth of MCF-7 cells in a dose-dependent manner, whereas growth of BT-474 and MCF-10A cells was suppressed by the maximum concentration (100nM) only. When treated in serum-free medium, all cell lines except of MDA-MB-231 were responsive to 1nM 3β-Adiol, and ZR75-1 cells exhibited a dose-dependent antiproliferative response. Providing putative mechanisms underlying the observed growth-inhibitory effect, expression of Ki-67 or cyclins A2 and B1 was downregulated after 3β-Adiol treatment in all responsive lines. In contrast, treatment with lower doses of Liquiritigenin did not affect growth. In MCF-7 cells, the highest dose of this flavonoid exerted proliferative effects accompanied by increased expression of cyclin B1, PR and PS2, indicating unspecific activation of ERα. In conclusion, the ERβ agonists tested exerted distinct concentration-dependent and cell line-specific effects on growth and gene expression. The observed inhibitory effects of 3β-Adiol on breast cancer cell growth encourage further studies on the potential of this and other ERβ agonists as targeted drugs for breast cancer therapy.

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.

Breast Cancer Therapy Based on Melatonin

The usefulness of melatonin and melatoninergic drugs in breast cancer therapy is based on its Selective Estrogen Receptor Modulator (SERM) and Selective Estrogen Enzyme Modulator (SEEM) properties. Because of the oncostatic properties of melatonin, its nocturnal suppression by light-at-night (LAN) has been considered a risk-factor for breast cancer. Melatonin's SERM actions include modulation of estrogen-regulated cell proliferation, invasiveness and expression of proteins, growth factors and proto-oncogenes (hTERT, p53, p21, TGFβ, E-cadherin, etc.). These actions are observable with physiologic doses of melatonin only in cells expressing ERα, and mediated by MT1 melatonin receptors. Melatonin acts like a SEEM, inhibiting expression and activity of P450 aromatase, estrogen sulfatase and type 1, 17β- hydroxysteroid dehydrogenase, but stimulating that of estrogen sulfotransferase. This double action mechanism (SERM and SEEM), and the specificity for ERα bestows melatonin with potential advantages for breast cancer treatments, associated with other antiestrogenic drugs, and idea already patented. LAN enhances the growth of rat mammary tumors by decreasing or suppressing melatonin production. Epidemiologic studies have also described increased breast cancer risk in women exposed to LAN. Since the strongest suppression of nocturnal melatonin occurs with wavelength light of the blue spectral region, optical and lightening devices filtering the blue light spectrum have been proposed to avoid the risks of light-induced suppression of nocturnal melatonin.

Abstract 3834: JKA97, a novel anti-cancer candidate, induces G1 arrest via up-regulation of p21 in a p53-independent manner

Abstract Breast cancer is one of the most commonly diagnosed cancers and the leading causes of cancer death in women worldwide. Natural product-oriented synthetic derivatives have played an important role in cancer drug discovery. JKA97, a benzylidene analog of harmine, is a novel anti-cancer candidate. The initial studies have shown its inhibitory effects on tumor growth in experimental models. However, the underlying molecular mechanisms are not fully elucidated. In this study, we determined the anti-cancer effects of JKA97 on human breast cancer in vitro and in vivo. Our data showed that, in a dose-dependent manner, JKA97 efficiently inhibited the growth and proliferation of human breast cancer cells with different p53 status, including MCF7 (p53 wild-type), MCF7 (p53 knockdown) and MDA-MB-468 (p53 mutant) cells. We also found that JKA97 induced apoptosis in human breast cancer cells independent of p53 and that JKA97 treatment resulted in G1 phase arrest in all the three breast cancer cell lines. In vivo, JKA97 significantly suppressed the growth of both breast cancer MCF7 and MDA-MB-468 xenograft tumors. Mechanistically, JKA97 modulated the levels of various cell-cycle regulators involved in G1 to S phase progression, such as p21, p27, cyclinE, and cyclinD1. Our results indicated that p21 and p27were up-regulated while cyclinE and cyclinD1 were down-regulated by JKA97 treatment. Using quantitative PCR and luciferase reporter assays, we demonstrated that the major mechanism for G1 phase arrest by JKA97 was induction of p21 at the transcriptional level, independent of p53. We further confirmed the role of p21 in JKA97-induced G1 phase arrest by using HCT116 cells with or without p21 expression. Taken together, these findings suggest that JKA97 inhibits human breast cancer by inducing cell cycle arrest through up-regulation of p21, regardless of p53 status. Considering that more than 50% human cancers have no or mutant p53 expression, our results provide a basis for further development of this compound as potential drug for breast cancer therapy. (This work was supported in part by NIH/NCI grants R01 CA112029 and R01 CA121211, R15 CA100102 and a grant (BCTR070731) from Susan G Komen for the Cure.) Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3834. doi:1538-7445.AM2012-3834

Clinicopathological and Biological Significance of Human Voltage-gated Proton Channel Hv1 Protein Overexpression in Breast Cancer

In our previous work, we showed for the first time that the voltage-gated proton channel Hv1 is specifically expressed in highly metastatic human breast tumor tissues and cell lines. However, the contribution of Hv1 to breast carcinogenesis is not well known. In this study, we showed that Hv1 expression was significantly correlated with the tumor size (p = 0.001), tumor classification (p = 0.000), lymph node status (p = 0.000), clinical stage (p = 0.000), and Her-2 status (p = 0.045). High Hv1 expression was associated significantly with shorter overall (p = 0.000) and recurrence-free survival (p = 0.000). In vitro, knockdown of Hv1 expression in the highly metastatic MDA-MB-231 cells decreased the cell proliferation and invasiveness, inhibited the cell proton secretion and intracellular pH recovery, and blocked the cell capacity of acidifying extracellular milieu. Furthermore, the gelatinase activity in MDA-MB-231 cells that suppressed Hv1 was reduced. In vivo, the breast tumor size of the implantation of the MDA-MB-231 xenografts in nude mice that were knocked down by Hv1 was dramatically smaller than that in the control groups. The results demonstrated that the inhibition of Hv1 function via knockdown of Hv1 expression can effectively retard the cancer growth and suppress the cancer metastasis by the decrease of proton extrusion and the down-regulation of gelatinase activity. Based on these results, we came to the conclusion that Hv1 is a potential biomarker for prognosis of breast cancer and a potential target for anticancer drugs in breast cancer therapy.

Direct spectroscopic evidence for binding of anastrozole to the iron heme of human aromatase. Peering into the mechanism of aromatase inhibition

Aromatase (CYP19A1), is a microsomal cytochrome P450 catalysing the conversion of androgens to estrogens. Non-steroidal inhibitors, such as anastrozole, are important drugs in breast cancer therapy. Using hyperfine sublevel correlation (HYSCORE) spectroscopy we provide the first experimental evidence of the binding of anastrozole to the iron heme of human aromatase.

Is it Time to Test Metformin in Breast Cancer Prevention Trials? a Reply to the Authors

To the Editor: We read with great interest the article by Cazzaniga et al. (1) on the potential use of the insulin sensitizing agent metformin for therapeutic and chemopreventive purposes in breast cancer. We found that the safety profile of metformin was inadequately elicited and poorly supported by the cited references. This was particularly striking with regard to lactic acidosis, defined by the authors as “the only potential adverse event in metformin therapy.” The authors further refer to this condition in terms of a rare event, which primarily occurs in patients with renal and hepatic disorders. The reported evidence was not exhaustive and the only cited reference was taken from an article published in 1996 (2). Given the current use of metformin in several common pathologic conditions associated with insulin resistance (e.g., type 2 diabetes and polycystic ovary syndrome) as well as the great potential of this drug in breast cancer therapy and prevention, the relation between metformin use and lactic acidosis in both diabetic and non diabetic patients is in urgent need of clarification particularly in light of much more recent and comprehensive scientific evidence.The Cochrane Collaboration has conducted a systematic review evaluating the risk of fatal and nonfatal acidosis attributed to metformin use compared with placebo and other agents in type 2 diabetes patients. Salpenter et al. (3) pooled data for a total of 59,321 patient-years of metformin use and 51,627 patient-years in the nonmetformin group. They found no evidence of the association between metformin use and risk of lactic acidosis.In nondiabetic patients, lactic acidosis occurs in association with pathologic conditions leading to tissue hypoxia, such as infections, heart failure, liver failure, and renal failure. In these cases, mortality is predicted by the severity of the underlying hypoxia and does not correlate with metformin accumulation (4, 5).In conclusion, when referring to the association between this drug use and lactic acidosis in an evaluation of the timeliness of testing metformin in breast cancer prevention trials, the following message should be clearly conveyed: although circumstantial evidence has linked metformin treatment with lactic acidosis, no causal relationship has been shown thus far, either in patients with type 2 diabetes or in nondiabetic patients. Conversely, this drug has been proven to reduce cardiovascular mortality in type 2 diabetes patients and, when considered in a preclinical setting, to possess anticarcinogenic properties on breast, colon, and prostate (1).No potential conflicts of interest were disclosed.