Distinct genes related to drug response identified in ER positive and ER negative breast cancer cell lines

Breast cancer patients have different responses to chemotherapeutic treatments. Genes associated with drug response can provide insight to understand the mechanisms of drug resistance, identify promising therapeutic opportunities, and facilitate personalized treatment. Estrogen receptor (ER) positive and ER negative breast cancer have distinct clinical behavior and molecular properties. However, to date, few studies have rigorously assessed drug response genes in them. In this study, our goal was to systematically identify genes associated with multidrug response in ER positive and ER negative breast cancer cell lines. We tested 27 human breast cell lines for response to seven chemotherapeutic agents (cyclophosphamide, docetaxel, doxorubicin, epirubicin, fluorouracil, gemcitabine, and paclitaxel). We integrated publicly available gene expression profiles of these cell lines with their in vitro drug response patterns, then applied meta-analysis to identify genes related to multidrug response in ER positive and ER negative cells separately. One hundred eighty-eight genes were identified as related to multidrug response in ER positive and 32 genes in ER negative breast cell lines. Of these, only three genes (DBI, TOP2A, and PMVK) were common to both cell types. TOP2A was positively associated with drug response, and DBI was negatively associated with drug response. Interestingly, PMVK was positively associated with drug response in ER positive cells and negatively in ER negative cells. Functional analysis showed that while cell cycle affects drug response in both ER positive and negative cells, most biological processes that are involved in drug response are distinct. A number of signaling pathways that are uniquely enriched in ER positive cells have complex cross talk with ER signaling, while in ER negative cells, enriched pathways are related to metabolic functions. Taken together, our analysis indicates that distinct mechanisms are involved in multidrug response in ER positive and ER negative breast cells.     

Induction of kinetochore positive and negative micronuclei in mouse bone marrow cells by salicylazosulfapyridine and sulfapyridine.

Salicylazosulfapyridine (SASP) and its major metabolite sulfapyridine (SP) have been shown to induce chromosomal damage in vivo. Both chemicals were tested in the micronucleus (MN)/kinetochore (KC) staining test to gain insight into the question of whether chromosomal breakage, aneuploidy-inducing events, or both were important to the observed production of MN in bone marrow cells of mice. In this test, both SASP and SP were shown to be strong inducers of kinetochore positive (KC+) MN. Although small increases in kinetochore negative (KC-) MN were also observed in SP treated mice, as well as in mice receiving the highest dose of SASP tested, the results suggest that both chemicals induce predominantly aneuploidogenic type damage.     

Isolation and characterization of stem-like cells from a human ovarian cancer cell line

Increasing evidence supports the existence of a subpopulation of cancer cells capable of self-renewal and differentiation into diverse cell lineages. These cancer stem-like or cancer-initiating cells (CICs) also demonstrate resistance to chemo- and radiotherapy and may function as a primary source of cancer recurrence. We report here on the isolation and in vitro propagation of multicellular ovarian cancer spheroids from a well-established ovarian cancer cell line (OVCAR-3). The spheroid-derived cells (SDCs) display self-renewal potential, the ability to produce differentiated progeny, and increased expression of genes previously associated with CICs. SDCs also demonstrate higher invasiveness, migration potential, and enhanced resistance to standard anticancer agents relative to parental OVCAR-3 cells. Furthermore, SDCs display up-regulation of genes associated with epithelial-to-mesenchymal transition (EMT), anticancer drug resistance and/or decreased susceptibility to apoptosis, as well as, down-regulation of genes typically associated with the epithelial cell phenotype and pro-apoptotic genes. Pathway and biological process enrichment analyses indicate significant differences between the SDCs and precursor OVCAR-3 cells in TGF-beta-dependent induction of EMT, regulation of lipid metabolism, NOTCH and Hedgehog signaling. Collectively, our results indicate that these SDCs will be a useful model for the study of ovarian CICs and for the development of novel CIC-targeted therapies.     

Isolation and molecular characterization of a mouse renal microvascular endothelial cell line

Murine endothelial cells (ECs) have proven difficult to obtain and maintain in culture. Long-term maintenance of normal ECs remains a difficult task. In this article we report the establishment of the first cellular line of renal microvascular endothelium obtained from normal tissue. Cells were isolated, cloned, and maintained by serial passages for longer than 24 mo, using endothelial cell growth supplement (ECGS) and gelatin-coated plates. Their morphology and ultrastructure, expression of von Willebrand factor, presence of smooth muscle alpha-actin, vimentin, cytokeratin filaments, capillary structures formed on Matrigel, and some typical ECs surface molecules were the criteria used to characterize cultured ECs. When examined for responsiveness to Shiga toxin-1, 13-20% of cytotoxicity was observed when coincubated with lipopolysaccharides. This cytotoxicity was not observed for normal lung ECs (1G11). Consequently, REC-A4 line retains characteristics of resting microvascular ECs and represents a useful in vitro model to study biological and physiopathological properties of renal endothelium.     

Isolation and characterization of an adriamycin-resistant breast tumor cell line

Summary An adriamycin-resistant human breast tumor cell line MDA-A1 ^R was generated by step-wise selection in increasing concentrations of drug from the parent cell line MDA-MB-231. MDA-A1 ^R cells grow as loosely attached cell aggregates with a doubling time of 28–32 h; the MDA-MB-231 parent cell line grows as a standard monolayer culture with a 20-h doubling time. The MDA-A1 ^R cell line is highly resistant to adriamycin compared to the parent cell line, and is cross-resistant to velban and colchicine suggestive of a multidrug resistance (MDR) phenotype. MDA-A1 ^R cells exhibit reduced net adriamycin conent as compared to the parent cell line. The MDR-associated P-glycoprotein gene is amplified approximately 10-to 30-fold in MDA-A1 ^R cells. P-glycoprotein sequences are overexpressed in the resistant cells and are stable for up to 13 wk after drug removal. Moreover, MDA-A1 ^R cells show the presence of very high levels of P-glycoprotein. MDA-A1 ^R is thus an in vitro model system to study the mechanism of MDR in human breast cancer. This work was supported in part by grant C30195 from the National Institute of health, Bethesda, MD. Portion of this study appeared as a poster presentation at the Tissue Culture Association meeting, Las Vegas, 1988.     

CXCR4 positive cells from Lewis lung carcinoma cell line have cancer metastatic stem cell characteristics

There is increasing evidence that cancer stem cells contribute to the initiation and propagation of many tumor. Therefore, to find out and identify the metastatic tumor stem-like cells in Lewis lung cancer cell line (LLC), the expression of CXCR4 was measured in LLC by flow cytometry and observed by laser scanning confocal microscope (LSCM). After the CXCR4(+) LLC cell was isolated from LLC by magnetic cell sorting, its properties were evaluated by their tumorigenic and metastatic potentials. CXCR4(+) cells were counted for 0.18% of the total number of LLC, and immunofluorescent staining cells were identified by LSCM. CXCR4(+) LLC suspension cultured in a serum-free medium, cell spheres expressed a high level of Sca-1. The chemotherapy sensitivity to cisplatin of CXCR4(+) LLC was lower than that of CXCR4(-) LLC. The expression of ABCG2 and IGF1R mRNA in CXCR4(+) LLC was higher than that in CXCR4(-) LLC (P < 0.01). Most of CXCR4(+) LLC cells were close to vascular endothelial cells, aberrant vasculature around it was forming. The expression of VEGF and MMP9 mRNA in CXCR4(+) LLC was higher than that in CXCR4(-) LLC (P < 0.05), the microvessel density (MVD) of CXCR4(+) subsets growing were higher than that of CXCR4(-) subsets growing tumor tissue (P < 0.01). The tumor size, volume, and metastatic foci in the lungs of CXCR4(+) LLC was significantly higher than that in CXCR4(-) LLC (P < 0.001). Similarly, elevated expression of MMP9 and VEGF was also positively associated with CXCR4(+) LLC. Our results demonstrated that CXCR4(+) cells from Lewis lung carcinoma cell line exhibit cancer metastatic stem cell characteristics.     

Isolation and genetic characterization of dibucaine-resistant variants of a mouse lymphocytic cell line

A series of dibucaine-resistant (Dib^R) variants of the mouse lymphoid cell line L5178Y have been induced by mutagen (EMS) and isolated by selection for resistance to a short (48 h), high concentration (0.045 mM) drug pulse. Dib^R isolates grow exponentially in the presence of 0.025-– 0.030 mM dibucaine, drug concentrations that are toxic to the parent cell line. Like L5178Y, these variants are pseudodiploid. The dibucaine-resistant phenotype has remained stable in four independently derived populations, subcultured for 7 or 11 months in growth medium without drug. Also, the frequency of Dib^R variants increases as the concentration of inducing mutagen is increased. These latter two findings suggest, but do not prove, that the dibucaine-resistant phenotype occurs because of gene mutation. All Dib^R isolates were found to be cross-resistant to the growth-inhibiting effects of tetracaine, but sensitive to procaine and benzocaine. Chromosome number or cell size is an important consideration in evaluating the cytotoxicity of dibucaine because normal pseudotetraploid cells are more tolerant to the toxic effects of this drug than are wild-type pseudodiploid cell populations. Hybridization studies indicate that the dibucaine-resistant phenotype of one variant may be dominant, and that of another recessive. Dib^R variants will be important for future studies of the mechanism of local anesthetic action.     

Isolation and characterization of lectin-resistant mouse cell lines defective in their ability to yield hybrid cells

Lectin-resistant variants of the mouse mammary tumor cell line FM3A in suspension were isolated after multiple-step selection using toxic concentrations of phytohemagglutinin (PHA) and concanavalin A (Con A). In fusion experiments, both PHA- and Con A-resistant lines were found to have lost the ability to yield hybrids with suspension-grown cells, although they were capable of yielding hybrids with monolayer-grown cells. This phenotype of PHA-resistant lines was stable during a long period of culture in the absence of PHA.     

TNF inhibitor suppresses bone metastasis in a breast cancer cell line

In the evolution of cancer, tumor necrosis factor-alpha (TNF-α) plays a paradoxical role. High doses induce significant anticancer effects, but conversely, physiologic and pathologic levels of TNF-α may be involved in cancer promotion, tumor growth, and metastasis.Infliximab is a chimeric murine monoclonal antibody that binds with high affinity to soluble and membrane TNF-α and inhibits binding of TNF-α to its receptors. In the present study, we investigated the effect of infliximab, a TNF-α antagonist, on breast cancer aggressiveness and bone metastases.Infliximab greatly reduced cell motility and bone metastases in a metastatic breast cancer cell line, MDA-MB-231. The mechanism of bone metastasis inhibition involved decreased expression of CXC chemokine receptor 4 (CXCR4) and increased expression of decorin, which is the prototype of an expanding family of small leucine-rich proteoglycans. These results suggest a novel role for TNF-α inhibition in the reduction or prevention of bone metastases in this breast cancer model. Our study suggests that inhibition of TNF-α using infliximab may become a preventive therapeutic option for breast cancer.     

Isolation and characterization of mesenchymal stem cells from chicken bone marrow

The bone marrow mesenchymal stem cells (BMSCs) are multipotent stem cells, which can differentiate in vitro into many cell types. However, the vast majority of experimental materials were obtained from human, mouse, rabbit and other mammals, but rarely in poultry. So, in this study, Thirty- to sixty-day old chicken was chosen as experimental animal, to isolate and characterize BMSCs from them. To investigate the biological characteristics of chicken BMSCs, immunofluorescence and RT-PCR were used to detect the characteristic surface markers of BMSCs. Growth curves were drawn in accordance with cell numbers. To assess the differentiation capacity of the BMSCs, cells were induced to differentiate into osteoblasts, adipocytes, and endothelial cells. The surface markers of BMSCs, CD29, CD44, CD31, CD34, CD71 and CD73, were detected by immunofluorescence and RT-PCR assays. The growth curves of different passages were all typically sigmoidal. Karyotype analysis showed that these in vitro cultured cells were genetically stable. In addition, BMSCs were successfully induced to differentiate into osteoblasts, adipocytes, and endothelial cells. The results suggest that the BMSCs isolated from chicken possess similar biological characteristics with those separated from other species, and their multi-lineage differentiation potentiality herald a probable application for cellular transplant therapy in tissue engineering.     

TNF inhibitor suppresses bone metastasis in a breast cancer cell line

C-reactive protein (CRP) is one of the most important biomarker for cardiovascular diseases. Recent studies have shown that CRP affects cell survival, differentiation and apoptosis. However, the effect of CRP on the cell cycle has not been studied yet. We investigated the cell cycle alterations and cellular mechanisms induced by CRP in H9c2 cardiac myocytes. Flow cytometry analysis showed that CRP-treated H9c2 cells displayed cell cycle arrest in G0/G1 phase. CRP treatment resulted in a significant reduction in the levels of CDK4, CDK6 and cyclin D1 in a concentration-dependent manner. Interestingly, CRP caused an increase in the p53 accumulation and its phosphorylation on Ser15, leading to induce p21 upregulation. Treatment with a specific p53 inhibitor, PFT-α restored the levels of CDK4 and CDK6. A significant increase of ERK1/2 phosphorylation level was detected in CRP-treated cells. Furthermore, pretreatment of a specific ERK inhibitor resulted in decreased p53 phosphorylation and p21 induction. ERK inhibitor pretreatment induced significant restoration of protein levels of CDK4 and CDK6, leading to re-entry into the cell cycle. In addition, increased phosphorylation of p53 and ERK induced by CRP was considerably reversed by Fc gamma receptor IIIa (FcγRIIIa) knock-down using siRNA. FcγRIIIa siRNA transfection also restored the levels of cell cycle proteins. Our study has provided the first proposal on the novel insights into how CRP directly affects cell cycle in cells.     

Isolation of osteoprogenitors from murine bone marrow by selection of CD11b negative cells

Selection of cells having the most osteogenic potential is a strategy used in bone tissue engineering. Preclinical studies using murine bone marrow cells must consider the large amount of hematopoietic cells in the adherent fraction. The aim of this study was to enrich a murine bone marrow cell population with osteoprogenitors by using a simple and reliable method. Bone marrow from C57Bl/6 mice was extracted and cells which adhered onto plastic were expanded in primary culture for 14 days. Immunolabeling of the CD11b surface antigen was performed and the CD11b⁻ cell fraction was isolated by FACS. Sorted and unsorted populations were analyzed for gene expression of osteoblast differentiation, alkaline phosphatase (AlkP) activity and matrix mineralization capacities. Selection of CD11b⁻ cells increased the number of AlkP⁺ cells from the plastic adherent fraction from 6.3% ± 0.8 to 56% ± 3.3 with a sevenfold increase in AlkP activity. mRNA analysis revealed a significant increase in the CD11b⁻ fraction for Osterix (41-fold), RANKL (17-fold), M-CSF (8-fold) and Runx-2 (8-fold). An osteogenic population was obtained with improved capacities to produce a mineralized extracellular matrix in vitro, independently of the presence of glucocorticoids in the culture medium.     

DNA-repair kinetics and the sensitivity of cells to X-ray-induced chromosome aberrations: a mouse myeloid leukemia cell line and normal mouse bone marrow cells

The frequency of X-ray-induced chromosome aberrations in G1 ML-1 mouse myeloid leukemia cells and normal mouse bone marrow cells increased with post-irradiation incubation with the DNA-repair resynthesis inhibitor 1-beta-D-arabinofuranosylcytosine (araC), but the frequency of aberrations in the leukemic cells increased with quite a different time response compared to the normal cells. Irradiated normal mouse bone marrow cells had a rapid increase in the frequency of chromosome exchanges and deletions with increasing araC incubation time, for example, an increase was observed with 0.5 h araC incubation. In contrast, the ML-1 cells did not have a significant increase in aberrations until 1-2 h post-irradiation incubation with araC. These results suggest that the ML-1 cells, per unit time, initially undergo less repair of the X-ray-induced DNA damage that can be converted into chromosome aberrations. We previously showed that the ML-1 cells have a higher frequency of X-ray-induced chromosome aberrations compared to normal cells and the results presented here indicate that a slower rate of repair resynthesis is contributing to the increased sensitivity of the ML-1 cells.     

Isolation and enrichment of skeletal muscle progenitor cells from mouse bone marrow

There is great interest in the therapeutic potential of non-hematopoietic stem cells obtained from bone marrow called mesenchymal stem cells (MSCs). Rare myogenic progenitor cells in MSC cultures have been shown to convert into skeletal muscle cells in vitro and also in vivo after transplantation of bone marrow into mice. To be clinically useful, however, isolation and expansion of myogenic progenitor cells is important to improve the efficacy of cell transplantation in generating normal skeletal muscle cells. We introduced into MSCs obtained from mouse bone marrow, a plasmid vector in which an antibiotic (Zeocin) resistance gene is driven by MyoD and Myf5 enhancer elements, which are selectively active in skeletal muscle progenitor cells. Myogenic precursor cells were then isolated by antibiotic selection, expanded in culture, and shown to differentiate appropriately into multinucleate myotubes in vitro. Our results show that using a genetic selection strategy, an enriched population of myogenic progenitor cells, which will be useful for cell transplantation therapies, can be isolated from MSCs.     

Isolation and characterisation of mesenchymal stem cells from adult mouse bone marrow

The future use of adult mesenchymal stem cells (MSCs) for human therapies depends on the establishment of preclinical studies with other mammals such as mouse. Surprisingly, purification and characterisation of murine MSCs were only poorly documented. The aim of this study was to purify mouse MSCs from adult bone marrow and to functionally characterise their abilities to differentiate along diverse lineages. Adherent cells from adult C57Bl/6J mouse bone marrow were depleted of granulo-monocytic cells and subsequently allowed to grow on fibronectin-coated dishes in presence of fetal bovine serum and growth factors. The growing fibroblastoid cell population primarily consisted of spindle- and star-shaped cells with significant renewal capacity as they were cultured until 30 passages (about 60 doubling population). We fully demonstrated the MSC phenotype of these cells by inducing them to differentiate along osteoblastic, adipocytic, and chondrocytic pathways. Mouse MSCs (mMSCs) sharing the same morphological and functional characteristics as human MSCs can be successfully isolated from adult bone marrow without previous mouse or bone marrow treatment. Therefore, mMSCs will be an important tool to study the in vivo behaviour and fate of this cell type after grafting in mouse pathology models.