Classification of Breast Cancer Cells on the Basis of a Functional Assay for Estrogen Receptor

Synthesis and Evaluation of Novel Metacetamol Derivatives with Hydrazone Moiety as Anticancer and Antimicrobial Agents

By exploiting the wide biological potential of the hydrazone scaffold, a series of hydrazone derivatives were synthesized, starting from N-(3-hydroxyphenyl)acetamide (metacetamol). The structures of the compounds were determined using IR, 1 H and 13 C-NMR, and mass spectroscopic methods. The obtained molecules (3 a-j) were evaluated for their anticancer potential against MDA-MB-231 and MCF-7 breast cancer cell lines. According to the CCK-8 assay, all tested compounds showed moderate to potent anticancer activity. Among them, N-(3-(2-(2-(4-nitrobenzylidene)hydrazinyl)-2-oxoethoxy)phenyl)acetamide (3 e) was found to be the most effective derivative with an IC50 value of 9.89 μM against MDA-MB-231 cell lines. This compound was further tested for its potential effects on the apoptotic pathway. Molecular docking studies was also carried out for 3 e in the colchicine binding pocket of tubulin. Additionally, compound 3 e also demonstrated effective antifungal activity, particularly against Candida krusei (MIC=8 μg/ml), indicating that nitro group at the 4th  position of the phenyl ring was the most preferable substituent for both cytotoxic and antimicrobial activity. Our preliminary findings suggest that compound 3 e could be exploited as a leading structure for further anticancer and antifungal drug development.

Genistein enhances the radiosensitivity of breast cancer cells via G₂/M cell cycle arrest and apoptosis

The aim of the present study was to investigate the radiosensitizing effect of genistein, and the corresponding mechanisms of action on breast cancer cells with different estrogen receptor (ER) status. Human breast cancer cell lines such as MCF-7 (ER-positive, harboring wild-type p53) and MDA-MB-231 (ER-negative, harboring mutant p53) were irradiated with X-rays in the presence or absence of genistein. Cell survival, DNA damage and repair, cell cycle distribution, cell apoptosis, expression of proteins related to G₂/M cell cycle checkpoint and apoptosis were measured with colony formation assays, immunohistochemistry, flow cytometry and western blot analysis, respectively. Genistein showed relatively weak toxicity to both cell lines at concentrations in the range of 5-20 μM. Using the dosage of 10 μM genistein, the sensitizer enhancement ratios after exposure to X-rays at a 10% cell survival (IC₁₀) were 1.43 for MCF-7 and 1.36 for MDA-MB-231 cells, respectively. Significantly increased DNA damages, arrested cells at G₂/M phase, decreased homologous recombination repair protein Rad51 foci formation and enhanced apoptotic rates were observed in both cell lines treated by genistein combined with X-rays compared with the irradiation alone. The combined treatment obviously up-regulated the phosphorylation of ATM, Chk2, Cdc25c and Cdc2, leading to permanent G₂/M phase arrest, and up-regulated Bax and p73, down-regulated Bcl-2, finally induced mitochondria-mediated apoptosis in both cell lines. These results suggest that genistein induces G₂/M arrest by the activation of the ATM/Chk2/Cdc25C/Cdc2 checkpoint pathway and ultimately enhances the radiosensitivity of both ER+ and ER- breast cancer cells through a mitochondria-mediated apoptosis pathway.

Human 21T breast epithelial cell lines mimic breast cancer progression in vivo and in vitro and show stage-specific gene expression patterns

Early breast cancer progression involves advancement through specific morphological stages including atypical ductal hyperplasia (ADH), ductal carcinoma in situ (DCIS) and invasive mammary carcinoma (IMC), although not necessarily always in a linear fashion. Observational studies have examined genetic, epigenetic and gene expression differences in breast tissues representing these stages of progression, but model systems which would allow for experimental testing of specific factors influencing transition through these stages are scarce. The 21T series cell lines, all originally derived from the same patient with metastatic breast cancer, have been proposed to represent a mammary tumor progression series. We report here that three of the 21T cell lines indeed mimic specific stages of human breast cancer progression (21PT-derived cells, ADH; 21NT-derived cells, DCIS; 21MT-1 cells, IMC) when grown in the mammary fat pad of nude mice, albeit after a year. To develop a more rapid, readily manipulatable in vitro assay for examining the biological differences between these cell lines, we have used a 3D Matrigel system. When the three cell lines were grown in 3D Matrigel, they showed characteristic morphologies, in which quantifiable aspects of stage-specific in vivo behaviors (ie, differences in acinar structure formation, cell polarization, colony morphology, cell proliferation, cell invasion) were recapitulated in a reproducible fashion. Gene expression profiling revealed a characteristic pattern for each of the three cell lines. Interestingly, Wnt pathway alterations are particularly predominant in the early transition from 21PTci (ADH) to 21NTci (DCIS), whereas alterations in expression of genes associated with control of cell motility and invasion phenomena are more prominent in the later transition of 21NTci (DCIS) to 21MT-1 (IMC). This system thus reveals potential therapeutic targets and will provide a means of testing the influences of identified genes on transitions between these stages of pre-malignant to malignant growth.

Dihydroarteannuin ameliorates lupus symptom of BXSB mice by inhibiting production of TNF-alpha and blocking the signaling pathway NF-kappa B translocation

The aim of this study was to investigate the mechanisms of action of Dihydroarteannuin (DHA), a semi-synthesized agent from the starting material artemisinin extracted from the Chinese Traditional Herbs Artemisia annua, on ameliorating the symptoms of lupus on BXSB mice. The concentration of TNF-alpha in the culture supernatant of the peritoneal macrophages and in the sera of BXSB mice was determined by the ELISA method. NF-kappaB protein expression and translocation were assayed by the EMSA method and laser confocal scanning microscopy method, respectively. IkappaB-alpha and NF-kappaB p65 protein expression were determined by the Western blot method. Renal tissue of the BXSB mice was prepared for assaying inhibitory activity of DHA on NF-kappaB, p65 and IkappaB-alpha protein expression in vivo. The peritoneal macrophages were prepared for analysis inhibitory effects of DHA on translocation of NF-kappaB into nuclear in vitro. We found that DHA strongly reduced the production of TNF-alpha in the culture supernatant of the peritoneal macrophages and in the sera of BXSB mice in vitro or in vivo. The results demonstrated that DHA decreased the expression of NF-kappaB subunit p65 protein and the activation of NF-kappaB in the renal tissue of BXSB mice in vivo. DHA effectively inhibited the nuclear translocation of NF-kappaB in peritoneal macrophages of BXSB mice in vitro. Furthermore, it was demonstrated that the degradation of IkappaB-alpha protein was significantly inhibited by DHA. These observations suggested that the inhibitory effects of DHA on TNF-alpha production may result from the block in the NF-kappaB signaling pathway upstream of IkappaB degradation.

Molecular identification of ERalpha-positive breast cancer cells by the expression profile of an intrinsic set of estrogen regulated genes

Estrogens exert a key biological role in mammary gland epithelial cells and promote breast carcinogenesis and tumor progression. We recently identified a new large set of estrogen responsive genes from breast cancer (BC) cells by DNA microarray analysis of the gene expression profiles induced by 17beta-estradiol in ZR-75.1 and MCF-7 cells. The purpose of the present study was to test whether the expression pattern of hormone regulated genes from this set identifies estrogen receptor (ERalpha) positive, hormone responsive BC cells. To this aim, we carried out in silico metanalysis of ERalpha positive and ERalpha negative human BC cell line transcriptomes, focusing on two sets of 171 and 218 estrogen responsive genes, respectively. Results show that estrogen dependent gene activity in hormone responsive BC cells is significantly different from that of non-responsive cells and, alone, allows to discriminate these two cellular phenotypes. Indeed, we have identified 61 genes whose expression profile specifically marks ERalpha positive BC cells, suggesting that this gene set may be exploited for phenotypic characterization of breast tumors. This possibility was tested with data obtained by gene expression profiling of BC surgical samples, where the ERalpha positive phenotypes were highlighted by the expression profile of a subset of 27 such hormone responsive genes and four additional BC marker genes, not including ERs. These results provide direct evidence that the expression pattern of a limited number of estrogen responsive genes can be exploited to assess the estrogen signaling status of BC cells both in vitro and ex-vivo.

Selectivity of antibodies to estrogen receptors alpha and beta (ERalpha and ERbeta) for detecting DNA-bound ERalpha and ERbeta in vitro

Antibodies are widely used to detect estrogen receptor (ER) in ER-DNA complexes in electrophoretic mobility shift assays (EMSA). We compared the specificity of antibodies raised to different regions of ERalpha or ERbeta for detecting recombinant human ERalpha (rhERalpha) and recombinant rat ERbeta (rrERbeta) when bound to a consensus estrogen response element (ERE). ERalpha-specific antibodies specifically slowed the migration of the ER-ERE complex by 32 to 84% and inhibited rhERalpha-ERE binding by 17 to 75%. None of antibodies to ERbeta supershifted rhERalpha-ERE complex. Some ERalpha-specific antibodies increased whereas some decreased rrERbeta-ERE binding. Anti-ERbeta antibodies supershifted different amounts of the rrERbeta-ERE complex. Our results indicate that supershift and inhibition of ER-ERE interaction with a specific antibody are equally reliable in the detection of rhERalpha and rrERbeta. ERalpha antibody Ab10, antisera G20 and AT3B, and ERbeta-antiserum Y19 offered the best discrimination between ERalpha and ERbeta. Comparison of the peptide sequences against which various antibodies were raised indicate directions for new ERalpha and ERbeta- specific antibody development. We conclude that a cognate ER antibody that retards the migration of the ER-ERE complex by at least 40% or inhibits ER-ERE interaction by at least 8% provides a reliable detection of a specific ER isoform in EMSA.

Epidermal growth factor-induced nuclear factor kappa B activation: A major pathway of cell-cycle progression in estrogen-receptor negative breast cancer cells

The epidermal growth factor (EGF) family of receptors (EGFR) is overproduced in estrogen receptor (ER) negative (-) breast cancer cells. An inverse correlation of the level of EGFR and ER is observed between ER- and ER positive (+) breast cancer cells. A comparative study with EGFR-overproducing ER- and low-level producing ER+ breast cancer cells suggests that EGF is a major growth-stimulating factor for ER- cells. An outline of the pathway for the EGF-induced enhanced proliferation of ER- human breast cancer cells is proposed. The transmission of mitogenic signal induced by EGF-EGFR interaction is mediated via activation of nuclear factor kappaB (NF-kappaB). The basal level of active NF-kappaB in ER- cells is elevated by EGF and inhibited by anti-EGFR antibody (EGFR-Ab), thus qualifying EGF as a NF-kappaB activation factor. NF-kappaB transactivates the cell-cycle regulatory protein, cyclin D1, which causes increased phosphorylation of retinoblastoma protein, more strongly in ER- cells. An inhibitor of phosphatidylinositol 3 kinase, Ly294-002, blocked this event, suggesting a role of the former in the activation of NF-kappaB by EGF. Go6976, a well-characterized NF-kappaB inhibitor, blocked EGF-induced NF-kappaB activation and up-regulation of cell-cycle regulatory proteins. This low molecular weight compound also caused apoptotic death, predominantly more in ER- cells. Thus Go6976 and similar NF-kappaB inhibitors are potentially novel low molecular weight therapeutic agents for treatment of ER- breast cancer patients.

Progestin regulation of 11beta-hydroxysteroid dehydrogenase expression in T-47D human breast cancer cells

This study examined the enzymatic characteristics and steroid regulation of the glucocorticoid-metabolizing enzyme 11beta-hydroxysteroid dehydrogenase (11beta-HSD) in the human breast cancer cell line T-47D. In cell homogenates, exogenous NAD significantly increased the conversion of corticosterone to 11-dehydrocorticosterone, while NADP was ineffective. There was no conversion of 11-dehydrocorticosterone to corticosterone either with NADH or NADPH demonstrating the lack of reductase activity. In keeping with these results, RT-PCR analysis indicated a mRNA for 11beta-HSD2 in T-47D cells, while 11beta-HSD1 mRNA levels were undetectable. In T-47D cells treated for 24 h with medroxyprogesterone acetate (MPA), 11beta-HSD catalytic activity was elevated 11-fold, while estrone (E(1)), estradiol (E(2)) and the synthetic glucocorticoid dexamethasone (DEX) were ineffective. The antiprogestin mifepristone (RU486) acted as a pure antagonist of the progestin-enhanced 11beta-HSD activity, but did not exert any agonistic effects of its own. In addition, RT-PCR analysis demonstrated that MPA was a potent inducer of 11beta-HSD2 gene expression, increasing the steady-state levels of 11beta-HSD2 mRNA. Taken together, these results demonstrate that 11beta-HSD2 is the 11beta-HSD isoform expressed by T-47D cells under steady-state conditions and suggest the existence of a previously undocumented mechanism of action of progestins in breast cancer cells.

Calmodulin is essential for estrogen receptor interaction with its motif and activation of responsive promoter

Calmodulin (CaM) has been reported to have affinity for the estrogen receptor (ER). Observations reported here reveal a direct physical interaction between purified CaM and ER. This direct ER-CaM interaction may be an initial event preceding the assembly of ER plus auxiliary proteins into the active ER complex with its DNA motif, the estrogen response element. We demonstrate that CaM is an integral component of this complex by using a system reconstituted from purified ER and nuclear extract from ER-negative breast cancer cells and also with ER-depleted nuclear extract of an ER-positive breast cancer cell line. Although CaM is essential for formation of this complex, it is not sufficient, suggesting roles also of auxiliary proteins. CaM also is functionally required for activation of an ER-responsive promoter, in the 17beta-estradiol-ER pathway of hormone action and regulation of 17beta-estradiol-responsive gene expression that is associated with proliferation of mammary epithelial cells.