Breast Carcinoma Cell Line MCF-7 Research Articles

A thermally responsive Tat-elastin-like polypeptide fusion protein induces membrane leakage, apoptosis, and cell death in human breast cancer cells

The thermally responsive elastin-like polypeptide (ELP) has great potential as a macromolecular drug delivery vehicle due to its ability to be actively targeted to solid tumors by application of focused hyperthermia. Since, the toxicity properties of a new therapeutic delivery vehicle are crucial to its utility as an effective delivery vehicle, we evaluated the cytotoxicity of a thermally responsive Tat-ELP1 in various cell lines in response to hyperthermia. We report that Tat-ELP1 was not cytotoxic at 37°C in SK-MEL-2, SKOV-3 and WI-38 cells, and only mildly toxic in the MCF-7 breast carcinoma cell line. Application of hyperthermia (42°C) in combination with Tat-ELP1 resulted in cytotoxicity in all cell lines tested, and this toxicity was most prominent in the MCF-7 cell line, which was chosen to study the mechanism behind this increased toxicity. We found that Tat-ELP1 combined with hyperthermia caused membrane leakage and apoptosis, resulting in cell death, but no hemolytic effect was observed on murine erythrocytes.

Effects of Panax notoginseng, ginsenoside Rb1, and notoginsenoside R1 on proliferation of human breast carcinoma MCF-7 cells

In this study, we evaluated the antiproliferative effects of Panax notoginseng, ginsenoside Rb1, and notoginsenoside R1 in the human breast carcinoma MCF-7 cell line. Our results indicated that both Panax notoginseng radix extract (NRE) and Panax notoginseng rhizoma extract (NRhE) possess significant antiproliferative activities in MCF-7 cells. Compared to control group (100%), at the concentrations of 0.05, 0.5, and 1.0 mg/ml NRE, cell growth was concentration-dependently reduced to 81.0 6.1 (P 4.8 (P 1.9 (P

Decidualized and pre-decidualized normal endometrial stromal cells produce more O-linked N-acetylglucosamine containing epitope H than non-decidualized normal endometrial stromal cells.

The epitope H contains an O-linked N-acetylglucosamine residue in a specific conformation and/or environment recognized by the monoclonal antibody H (mAbH). mAbH stains two bands with Mr x10(-3) of 209 and 62 in lysates of cultured rat astrocytes. In addition, in extracts of cultured MCF-7 breast carcinoma cell line cells it stains cytokeratin 8 and five polypeptides originating from Triton X-100-soluble (Mr x10(-3) of 232, 67 and 37) and from the Triton X-100-insoluble (Mr x10(-3) of 51 and 50) fractions, respectively. In our previous studies we used the mAbH to investigate by immunostaining the expression of the epitope H in normal human brains, human brains with a variety of lesions, astrocytic tumors, infiltrating ductal breast carcinomas, fibroadenomas, and mitochondria-rich normal, metaplastic and neoplastic cells. In order to gain further insight into the expression patterns of the epitope H in human tissues we used the mAbH to investigate the immunohistochemical expression of the epitope H in normal human endometrium, including 30 cases of proliferative endometrium, 30 cases of early secretory endometrium, 30 cases of mid secretory endometrium, 30 cases of late secretory endometrium and 30 cases of decidual tissues. The main results were the following: 1) The decidual stromal cells presented in all cases high cytoplasmic expression of the epitope H; 2) The pre-decidual stromal cells presented in all cases of late secretory endometrium significant cytoplasmic expression of the epitope H ranging from moderate to high expression; 3) The non pre-decidual stromal cells of the functional endometrial layer presented in all cases insignificant cytoplasmic expression of the epitope H ranging from null to low expression; 4) The stromal cells of the basal layer of the endometrium and decidua did not express the epitope H in any case; 5) The endometrial stromal granulocytes did not express the epitope H in any case and 6) The blood vessel wall cells (endothelial and smooth muscle) of the endometrium through the whole duration of the menstrual cycle and of the decidua presented high cytoplasmic expression of the epitope H. It is concluded that decidualized and pre-decidualized human normal endometrial stromal cells show increased expression of the O-linked N-acetylglucosamine containing epitope H compared to non-decidualized endometrial stromal cells. These findings suggest that the expression of the epitope H may be under positive progesteronic control in normal human endometrium. Further investigation of the antigens bearing the epitope H might help to gain further insight into the histophysiology and the pathology of human endometrium.

Cell-cycle progression and response of germ cell tumors to cisplatin in vitro

Testicular germ cell tumors (GCTs) are highly sensitive to cisplatin-based chemotherapy. It has been suggested that the chemosensitivity of GCTs can be partially attributed to the preference of apoptosis induction over a p21-mediated G1/S phase cell-cycle arrest following induction of p53. Since cell-cycle progression can be manipulated by a growing number of targeted agents, a thorough understanding of the impact of cell-cycle progression on drug-induced cell death might help to enhance the efficacy of chemotherapy. The aim of this study was to assess the cell-cycle dependence of cisplatin-induced cell death in an in vitro model of GCTs. Cell-cycle progression and induction of apoptosis were assessed by flow cytometry and Western blot analysis of PARP cleavage in the GCT derived cell lines, NT2 and 2102 EP, and compared with the breast carcinoma cell line MCF-7. Response to treatment was assessed in different phases of the cell cycle after synchronization by serum depletion and contact inhibition. Following cisplatin exposure, unsynchronized cells accumulated in G2/M after 28 h. This arrest was reversible at sublethal cisplatin doses (0.5-4.5 microM for 2 h). At higher concentrations, cells accumulated in G2 and died in G2/M-arrest. A 2-h exposure of cells in G2/M with 10 microM cisplatin resulted in a higher apoptotic index 70 h after treatment (74 and 70% for NT2 and 2102 EP, respectively) compared to treatment in G1/S (34 and 38%). Synchronized cells treated in G1 showed PARP cleavage after 48 h following cisplatin exposure, whereas treatment in G2 resulted in PARP cleavage already after 24 h. Cisplatin-induced cell death in GCTs is highly dependent on cell-cycle phase. All crucial events are restricted to the G2/M phase: cisplatin-induced DNA-damage is sensed, the apoptotic process is initiated and eventually executed in this phase of the cell cycle. The cells are most sensitive to cisplatin in this phase of the cell cycle. As far as the development of targeted agents is concerned, inhibition of the cell cycle in G1/S phase is likely to result in a protective effect against cisplatin, whereas agents arresting cells in G2/M may exert a synergistic effect.

Proteomics analysis of a novel compound: Cyclic RGD in breast carcinoma cell line MCF-7

In studies of cell adhesion, migration, growth, differentiation, and apoptosis, synthetic peptides containing the RGD (Arg-Gly-Asp) motif have been extensively used as the inhibitors of integrin-ligand interactions. The RGD motif is an integrin-recognition motif found in many ligands, so that the RGD-containing peptides can be used to probe integrin functions in various biological systems. A linear RGD is a tripeptide consisting of a flexible structure that makes the motif bind to its receptor with inefficient chelating affinity. Therefore, we designed a cyclic-RGD peptide (Tpa-RGDWPC, cRGD) with rigid skeleton to closely bind with its receptor. The cRGD was obtained by solid-phase peptide synthesis method using Rink amide resin. We showed that the cRGD exerts more potency than linear RGD on inhibiting cell growth of MCF-7 breast carcinoma cells. This stimulated us to question how cRGD inhibits cell growth of MCF-7 cells. Moreover, understanding what molecular mechanism underlies the effect that RGD motif exerts on MCF-7 cells is also of considerable importance. We used proteomics and bioinformatics to survey the global changes in proteins after cRGD treatment in MCF-7 cells. The classification of these proteins is shown according to the different biological processes in which they are involved. Most of the proteins that appear to be strongly influenced by cRGD treatment are involved in metabolism, cell growth, responsive to external stimulus, cell communication, reproduction and cell death. This is the first report which monitors the protein expression profile of MCF-7 cells in response to treatment with RGD-containing peptides in a time-course analysis. The clustering data indicated temporal patterns of altered protein expression that can be categorized into early, intermediate and late response proteins. These patterns of protein expression may be important for predicting its response to cRGD. In summary, these results provide a molecular explanation for the properties of cRGD in breast cancer cells and present a valuable in-depth description of their possible impact on breast cancer therapy.

Identification of a new HLA-A2–restricted T-cell epitope within HM1.24 as immunotherapy target for multiple myeloma

The aim of this study was identification of human leukocyte antigen (HLA)-A2-restricted T-cell epitopes within the HM1.24 antigen as target for multiple myeloma (MM)-directed specific peptide-based immunotherapy. The HM1.24 sequence was scanned for immunogenic peptides using the HLA-binding prediction software SYFPEITHI and BIMAS. Peripheral blood mononuclear cells from HLA-A2(+) healthy volunteers/blood donors (ND) were stimulated with autologous HM1.24-peptide-loaded dendritic cells, and expanded in vitro. Activation of T cells was assessed by ELISpot and cytotoxicity by (51)Chromium ((51)Cr)-release assays. T2-cells pulsed with irrelevant peptide, the HM1.24(-)/HLA-A2(+) breast carcinoma cell line MCF-7 and the HM1.24(+)/HLA-A2(-) myeloma cell line RPMI-8226 were used as controls. Expression of the HM1.24 gene (BST2) was assessed using purified plasma cells and Affymetrix-U133A+B microarrays. Frequency of peptide-specific CD8(+) T cells was detected using the flow-cytometric tetramer technique. Of eight nona-peptides with the highest probability of binding to HLA-A2, the HM1.24 aa22-30 peptide (LLLGIGILV) showed the most frequent activation of CD8(+) T cells in healthy volunteers (specific activation in 8 of 11 [73%] ND; compared with 5-19% for the 7 other HM1.24 peptides). Antigen recognition by the HM1.24 aa22-30-specific CD8(+) T cells was HLA-A2-restricted (ELISpot with HLA-A2-blocking antibodies: median, 15; range, 14-18 spots/well; isotype-control antibodies: median, 47; range, 44-48). HM1.24-aa22-30-specific CD8(+) T cells lysed HLA-A2(+) myeloma-derived cell lines ((51)Cr-release assay: XG-1 vs MCF-7, 91% vs 0%; U266 vs MCF-7, 38% vs 4.2%; IM-9 vs RPMI-8226, 22% vs 0%). Using the cross-reactive Neisseria meningitidis peptide LLSLGIGILV-specific CD8(+) T cells recognizing target cells loaded with the HM1.24 aa22-30 peptide (LLLGIGILV) as well as the myeloma-derived cell line U266 could be expanded from MM patients. The HM1.24 gene was expressed at comparable levels by plasma cells from 65 MM patients, 7 patients with monoclonal gammopathy of undetermined significance, and 7 ND. HM1.24 aa22-30 is a newly identified HLA-A2-restricted T-cell epitope that is processed and presented by major histocompatibility complex class I. Specifically activated CD8(+) T cells are able to lyse MM cell lines. We conclude that HM1.24 aa22-30 represents a suitable candidate target for a specific peptide-based immunotherapy of MM.

Optimisation of Fixation Period on Biological Cells via Time-Lapse Elasticity Mapping

Chemical fixing is a standard approach for preserving the structural integrity of biological samples for downstream microscopy and analysis. However, the standard protocols are typically geared towards regular optical or fluorescence microscopy and this can lead to topographical artifacts during scanning probe microscopy imaging. Furthermore, there are many different fixatives and protocols available, and determining which is the most appropriate for a particular cell line (that will subsequently require imaging by scanning probe microscopy) is often important. The rationale for this study was to review fixation approaches in the context of probe microscopy and to determine whether elasticity mapping is a useful tool for estimating the optimal fixing duration. Our findings suggest that, for the human breast carcinoma cell line MCF7 fixed in 4% fresh buffered formaldehyde, the degree of cross linking approaches completeness within 30 min. Knowledge of this is important, particularly in the context of the adjunct technique of fluorescence microscopy as under fixation causes the loss of signals and poor preservation of morphological detail, whereas over fixation causes the loss of signals and increases background noise from non specific signals. Thus, such measurements represent the best compromise for fixation approaches in preparation for tandem scanning probe and fluorescence/confocal studies.

Camptothecin Induces Nuclear Export of Prohibitin Preferentially in Transformed Cells through a CRM-1-dependent Mechanism

Prohibitin is a growth-suppressive protein that has multiple functions in the nucleus and the mitochondria. Our earlier studies had shown that prohibitin represses the activity of E2F transcription factors while enhancing p53-mediated transcription. At the same time, prohibitin has been implicated in mediating the proper folding of mitochondrial proteins. We had found that treatment of cells with camptothecin, a topoisomerase 1 inhibitor, led to the export of prohibitin and p53 from the nucleus to the mitochondria. Here we show that the camptothecin-induced export of prohibitin occurs preferentially in transformed cell lines, but not in untransformed or primary cells. Cells that did not display the translocation of prohibitin were refractive to the apoptotic effects of camptothecin. The translocation was mediated by a putative nuclear export signal at the C-terminal region of prohibitin; fusion of the nuclear export signal (NES) of prohibitin to green fluorescence protein led to its export from the nucleus. Leptomycin B could inhibit the nuclear export of prohibitin showing that it was a CRM-1-dependent event driven by Ran GTPase. Confirming this, prohibitin was found to physically interact with CRM-1, and this interaction was significantly higher in transformed cells. Delivery of a peptide corresponding to the NES of prohibitin prevented the export of prohibitin to cytoplasm and protected cells from apoptosis. These results suggest that the regulated translocation of prohibitin from the nucleus to the mitochondria facilitates its pleiotropic functions and might contribute to its anti-proliferative and tumor suppressive properties.

Synthesis of the Proposed Structure of Mucoxin via Regio- and Stereoselective Tetrahydrofuran Ring-Forming Strategies

An enantioselective total synthesis of the proposed structure of mucoxin (1) is described. Mucoxin, an annonaceous acetogenin isolated from bioactive leaf extracts of Rollinia mucosa, is the first acetogenin containing a hydroxylated trisubstituted tetrahydrofuran (THF) ring. This natural product is a highly potent and specific antitumor agent against MCF-7 (breast carcinoma) cell lines (ED50 = 3.7 x 10(-3) microg/mL compared to adriamycin, ED50 = 1.0 x 10(-2) microg/mL). The total synthesis described herein features two regio- and stereoselective THF ring-forming reactions. The 2,3,5-trisubstituted THF portion (C13-C17) was accessed using a highly regioselective cyclization of a methylene-interrupted epoxydiol, and the 2,5-disubstituted THF ring (C8-C12) was conveniently assembled via a 1,2-n-triol cyclization strategy. The spectral data of the synthetic material and two of its diastereomers did not match the reported data for the natural product. On the basis of detailed spectroscopic analysis of the synthesized molecule, we reason that the spectral discrepancies are due to stereochemical misassignment of the natural product.

Triterpene Acids from the Leaves ofPlanchonella Duclitan(Blanco) Bakhuizan

From the methanolic extract of the leaves of Planchonella duclitan, 2α,3α,19α,23-tetrahydroxy-13,27-cyclours-11-en-28-oic acid (1), myrianthic acid (2), 2-hydroxyursolic acid (3), ursolic acid (4), pomolic acid (5), rotundic acid (6), andjacoumaric acid (7) were isolated, and their structures were elucidated on the basis of their spectroscopic analysis. Among them, compound 1 was a new cyclopropyl ursane-type triterpene acid. Additionally, compounds 4 and 7 showed significant cytotoxicity toward human colorectal carcinoma cell line HT29 and human breast carcinoma cell line MCF-7 with IC 50 values ranging from 5.8 ± 1.4 to 6.5 ± 1.9 μM.

Estrogenic effect of procymidone through activation of MAPK in MCF-7 breast carcinoma cell line

Procymidone modifies sexual differentiation in vitro and induces estrogenic activity in primary cultured rainbow trout hepatocytes, as shown by an increase in the contents of vitellogenin and heat shock proteins. Since this dicarboximide fungicide is found in human tissues, it was considered of interest to investigate its ability to induce endocrine damage in the MCF-7 human cell line. The mechanism of this estrogenic action was also evaluated. Procymidone 100 μM stimulated cell growth from day 3 up to day 12 and raised the level of pS2 on day 3. Although procymidone does not bind the estrogen receptor (ER), the antiestrogen ICI 182780 inhibited its effect on cell growth and pS2 content, suggesting that the ER is involved indirectly in these effects. In exploring the mechanism of ER indirect activation we found that the antibody against c-Neu receptor (9G6) did not modify procymidone's effects on cell growth and pS2 expression. Thus, procymidone does not bind the c-Neu membrane receptor, excluding this indirect ER activation pathway. We also found that procymidone induced mitogen-activated protein kinase (MAPK) at 15 and 30 min, and that PD 98059, a MAPK (Erk1/2) inhibitor, prevented procymidone's effects on cell growth and pS2, indicating that MAPK activation is responsible for procymidone ER activation. The production of reactive oxygen species (ROS) with these times and elimination of the phenomenon by α-tocopherol (α-T), a ROS scavenger, is proof that oxygen free-radical production is at the basis of the MAPK activation by procymidone.

Effects of combined treatment with rapamycin and cotylenin A, a novel differentiation-inducing agent, on human breast carcinoma MCF-7 cells and xenografts

IntroductionRapamycin, an inhibitor of the serine/threonine kinase target of rapamycin, induces G1 arrest and/or apoptosis. Although rapamycin and its analogues are attractive candidates for cancer therapy, their sensitivities with respect to growth inhibition differ markedly among various cancer cells. Using human breast carcinoma cell line MCF-7 as an experimental model system, we examined the growth-inhibitory effects of combinations of various agents and rapamycin to find the agent that most potently enhances the growth-inhibitory effect of rapamycin.MethodWe evaluated the growth-inhibitory effect of rapamycin plus various agents, including cotylenin A (a novel inducer of differentiation of myeloid leukaemia cells) to MCF-7 cells, using either MTT assay or trypan blue dye exclusion test. The cell cycle was analyzed using propidium iodide-stained nuclei. Expressions of several genes in MCF-7 cells with rapamycin plus cotylenin A were studied using cDNA microarray analysis and RT-PCR. The in vitro results of MCF-7 cells treated with rapamycin plus cotylenin A were further confirmed in vivo in a mouse xenograft model.ResultsWe found that the sensitivity of rapamycin to MCF-7 cells was markedly affected by cotylenin A. This treatment induced growth arrest of the cells at the G1 phase, rather than apoptosis, and induced senescence-associated β-galactosidase activity. We examined the gene expression profiles associated with exposure to rapamycin and cotylenin A using cDNA microarrays. We found that expressions of cyclin G2, transforming growth factor-β-induced 68 kDa protein, BCL2-interacting killer, and growth factor receptor-bound 7 were markedly induced in MCF-7 cells treated with rapamycin plus cotylenin A. Furthermore, combined treatment with rapamycin and cotylenin A significantly inhibited the growth of MCF-7 cells as xenografts, without apparent adverse effects.ConclusionRapamycin and cotylenin A cooperatively induced growth arrest in breast carcinoma MCF-7 cells in vitro, and treatment with rapamycin and cotylenin A combined more strongly inhibited the growth of MCF-7 cells as xenografts in vivo than treatment with rapamycin or cotylenin A alone, suggesting that this combination may have therapeutic value in treating breast cancer. We also identified several genes that were markedly modulated in MCF-7 cells treated with rapamycin plus cotylenin A.

Activity of [1,2-di(cyclopentadienyl)-1,2-di(p-N,N-dimethylaminophenyl)-ethanediyl] titanium dichloride against tumor colony-forming units

[1,2-di(cyclopentadienyl)-1,2-di(p-N,N-dimethylaminophenyl)-ethanediyl] titanium dichloride is a newly synthesized transition metal-based anti-cancer drug. We studied the anti-tumor activity of this drug (final concentrations: 25, 250 and 2,500 micromol/l) against freshly explanted human tumors, using an in vitro soft agar cloning system. A total of eight tumor samples were evaluated using 1-h exposures. Additionally, the breast carcinoma cell line MCF-7 was examined with regard to sensitivity. The tested compound was markedly active against one renal cancer sample, whereas other renal tumors were resistant. Concentration-dependent anti-tumor activity was demonstrated for all samples except for melanoma. At concentrations of 250 micromol/l or less, the compound was less active than cisplatin or equally active at 0.2 microg/ml, whereas at 2,500 micromol/l it showed a significant cytotoxic activity against a wide spectrum of tumor types. The highest activity was observed against renal carcinomas (three of three tumor specimens inhibited at 2,500 micromol/l). Sensitivity was also highly remarkable in the breast cancer cell line MCF-7 inhibited in a range of 25-2,500 micromol/l, whereas melanoma cells seemed to be profoundly resistant. Further clinical development of this drug appears warranted because of the broad cytotoxic activity shown.

Human embryonic stem cell genes OCT4, NANOG, STELLAR, and GDF3 are expressed in both seminoma and breast carcinoma

The seminoma class of testicular germ cell tumor (TGCT) are characterized by a morphological resemblance to primordial germ cells (PGCs) or gonocytes, and chromosome duplications at 12p. Recently, it was determined that human embryonic stem cells (hESCs) express genes in common with PGCs, and that three of these genes, GDF3, STELLAR, and NANOG, are located on 12p. The current study was designed to identify whether expression of these 12p genes were elevated in seminoma relative to normal testis, and to determine whether elevated expression was unique to seminoma. Real-time polymerase chain reaction (PCR) and immunohistochemistry were used to assess gene expression in seminoma samples relative to normal testis and endpoint PCR was used to identify the presence or absence of these genes in breast carcinoma. GDF3 expression was increased in eight of nine seminomas compared with normal testis, whereas NANOG, OCT4, or both were expressed at the highest levels in seminoma compared with all other markers analyzed. In addition, the NANOG protein was expressed in the majority of seminoma cells. The adult meiotic germ cell markers BOULE and TEKT1 were undetectable in seminoma, whereas the embryonic and adult germ cell markers DAZL and VASA were significantly reduced. Analysis of these markers in breast carcinoma and the MCF7 breast carcinoma cell line revealed that a core hESC-transcriptional profile could be identified consisting of OCT4, NANOG, STELLAR, and GDF3 and that NANOG protein could be detected in breast carcinoma. These observations suggest that seminoma and breast carcinoma express a common stem cell profile and that the expression of DAZL and VASA in seminoma mark the germ cell origin of seminoma that is absent in breast carcinoma. Our findings suggest that stem cell genes may either play a direct role in different types of carcinoma progression or serve as valuable markers of tumorigenesis.

Antitumor Activity of C-Methyl-β-d-ribofuranosyladenine Nucleoside Ribonucleotide Reductase Inhibitors

A series of adenosine derivatives substituted at the 1'-, 2'-, or 3'-position of the ribose ring with a methyl group was synthesized and evaluated for antitumor activity. From this study 3'-C-methyladenosine (3'-Me-Ado) emerged as the most active compound, showing activity against human myelogenous leukemia K562, multidrug resistant human leukemia K562IU, human promyelocytic leukemia HL-60, human colon carcinoma HT-29, and human breast carcinoma MCF-7 cell lines with IC(50) values ranging from 11 to 38 muM. Structure-activity relationship studies showed that the structure of 3'-Me-Ado is crucial for the activity. Substitution of a hydrogen atom of the N(6)-amino group with a small alkyl or cycloalkyl group, the introduction of a chlorine atom in the 2-position of the purine ring, or the moving of the methyl group from the 3'-position to other ribose positions brought about a decrease or loss of antitumor activity. The antiproliferative activity of 3'-Me-Ado appears to be related to its ability to deplete both intracellular purine and pyrimidine deoxynucleotides through ribonucleotide reductase inhibition.

Protein profile changes in the human breast cancer cell line MCF‐7 in response to SEL1L gene induction

The ectopic expression of the gene SEL1L in the human breast carcinoma cell line MCF-7 resulted in a reduction of the aggressive behaviour of these cells in vitro. In addition, in vivo analysis on a series of primary breast carcinomas revealed an association between the SEL1L protein levels and the patient's overall survival. We aimed to find those proteins, associated with SEL1L, which may be involved in modulating the aggressive or invasive behaviour of breast cancer cells. For this purpose, we used both the proteomic and microarray approaches. Image analysis of two-dimensional electropherograms revealed the presence of 27 qualitative and 35 quantitative variations between the MCF7-SEL1L expressing cells compared to control. Mass spectrometry identified 32 changing proteins mostly involved in cytoskeletal and metabolic activities, stress response and protein folding, selenoprotein synthesis and cellular proliferation. Five of these also showed changes in transcript levels, as assessed by Affymetrix microarray analysis. Interestingly, seven proteins: carbonic anhydrase (CA) II, ovarian/breast septin, S100A16 calcium binding protein, 14-3-3 protein sigma, proteasome subunit beta type 6, Hsp60 and protein disulphide-isomerase A3 merit particular attention since they are known to be involved in cancer, in response to cellular stress and in protein folding.

The extracellular matrix composition and responsiveness to breast carcinoma therapy

It is established that stroma surrounding breast carcinoma can be altered in comparison with its normal counterpart, and histological observations recognize lesions with loose stroma rich in hyaluronic acid (HA) and recognize lesions with dense stroma rich in fibulin-1, collagens, laminins, fibronectin and fibrillins. Previous studies have shown that adhesion of tumor cells to different extracellular matrix (ECM) components interferes with drug responses. Thus, to address the functional and biological behavior of the breast cancer-related ECM proteins in response to cytotoxic treatments, the breast carcinoma cell line MDAMB361 was injected into athymic mice in the presence of a matrix containing high levels of fibulin-1, laminin-1 and collagens. The grown tumors displayed significantly (P = 0.01) reduced sensitivity to DXR compared with the same cells injected without the matrix, strongly indicating that the ECM milieu of tumor impacts the responsiveness of tumor cells to drugs. The analysis of changes in the ECM components in response to DXR treatment revealed that the human breast carcinoma cell lines SKBR-3, MCF-7, MDAMB157 and MDAMB361 upmodulated fibulin-1 transcript [1] and protein levels, particularly in a form exhibiting a molecular weight (about 50 kDa) lower than expected (about 74 kDa), thus suggesting that tumor cells may actively reorganize their matrix environment. In parallel with the increase of fibulin-1 the same stress conditions determined decreased expression of hyaluronan synthetases, the enzymes involved in the synthesis of HA. These preliminary findings provide support for a role of ECM in response to drugs and suggest that reorganization of the ECM following chemotherapy is the basis of drug-induced resistance.

RACK1-mediated Integration of Adhesion and Insulin-like Growth Factor I (IGF-I) Signaling and Cell Migration Are Defective in Cells Expressing an IGF-I Receptor Mutated at Tyrosines 1250 and 1251

The scaffolding protein receptor for activated C kinase (RACK1) has been proposed to mediate the integration of insulin-like growth factor I receptor (IGF-IR) and adhesion signaling. Here we investigated the mechanism of this integration of signaling, by using an IGF-IR mutant (Y1250F/Y1251F) that is deficient in anti-apoptotic and transforming function. RACK1 was found to associate with the IGF-IR only in adherent cells and did not associate with the IGF-IR in nonadherent cells, lymphocytic cells, or cells expressing the Y1250F/Y1251F mutant. In R- cells transiently expressing the Y1250F/Y1251F mutant RACK1 became constitutively associated with beta1 integrin and did not associate with Shc, Src, or Shp2. This was accompanied by the loss of formation of a complex containing the IGF-IR, RACK1, and beta1 integrin; loss of migratory capacity; enhanced Src and FAK activity; enhanced Akt phosphorylation; and decreased p38 mitogen-activated protein kinase activity. Shc was not phosphorylated in response to IGF-I in cells expressing the Y1250F/Y1251F mutant and remained associated with protein phosphatase 2A. Similar alterations in signaling were observed in cells that were stimulated with IGF-I in nonadherent cultures. Our data suggest that disruption of RACK1 scaffolding function in cells expressing the Y1250F/Y1251F mutant results in the loss of adhesion signals that are necessary to regulate Akt activity and to promote turnover of focal adhesions and cell migration.

Predictive value of serum interleukin-8 levels in ovarian cancer patients treated with paclitaxel-containing regimens

Previous findings showed that paclitaxel induces interleukin-8 (IL-8) transcription and secretion in ovarian cancer cellsin vitro. We hypothesized that paclitaxel treatment, which is a standard care for ovarian cancer patients, may increase the secretion of IL-8, resulting in the elevated serum IL-8 levels. In this study, we investigated the relationship between paclitaxel exposure and IL-8 levels of an ovarian and a breast carcinoma cell linein vitroand serums of patients with ovarian carcinoma. Both MDAH 2774 ovarian and MCF-7 breast carcinoma cell lines were sensitive to paclitaxel-mediated cytotoxicity. However, supernatant levels of IL-8 assessed by enzyme-linked immunosorbent assay before and after treatment with different concentrations of paclitaxel were significantly lower in MCF-7 than in MDAH 2774. Serum IL-8 levels were measured in serum samples from patients with ovarian carcinoma before and after paclitaxel-containing treatment regimens. Forty-eight patients were included in the study. The basal level of IL-8 after paclitaxel-containing treatment was found to be significantly higher in the serums of patients who had high tumor burden than in patients who had optimal debulking surgery and low tumor burden. These data strongly suggest that IL-8 may be an important predictive marker for tumor volume as well as sensitivity to paclitaxel.

Predictive value of serum interleukin-8 levels in ovarian cancer patients treated with paclitaxel-containing regimens

Previous findings showed that paclitaxel induces interleukin-8 (IL-8) transcription and secretion in ovarian cancer cells in vitro. We hypothesized that paclitaxel treatment, which is a standard care for ovarian cancer patients, may increase the secretion of IL-8, resulting in the elevated serum IL-8 levels. In this study, we investigated the relationship between paclitaxel exposure and IL-8 levels of an ovarian and a breast carcinoma cell line in vitro and serums of patients with ovarian carcinoma. Both MDAH 2774 ovarian and MCF-7 breast carcinoma cell lines were sensitive to paclitaxel-mediated cytotoxicity. However, supernatant levels of IL-8 assessed by enzyme-linked immunosorbent assay before and after treatment with different concentrations of paclitaxel were significantly lower in MCF-7 than in MDAH 2774. Serum IL-8 levels were measured in serum samples from patients with ovarian carcinoma before and after paclitaxel-containing treatment regimens. Forty-eight patients were included in the study. The basal level of IL-8 after paclitaxel-containing treatment was found to be significantly higher in the serums of patients who had high tumor burden than in patients who had optimal debulking surgery and low tumor burden. These data strongly suggest that IL-8 may be an important predictive marker for tumor volume as well as sensitivity to paclitaxel.