Routine culturing of normal, dysplastic and malignant human mammary epithelial cells from small tissue samples

Short-term spheroid culture of primary colorectal cancer cells as an in vitro model for personalizing cancer medicine

Chemotherapy treatment of cancer remains a challenge due to the molecular and functional heterogeneity displayed by tumours originating from the same cell type. The pronounced heterogeneity makes it difficult for oncologists to devise an effective therapeutic strategy for the patient. One approach for increasing treatment efficacy is to test the chemosensitivity of cancer cells obtained from the patient’s tumour. 3D culture represents a promising method for modelling patient tumours in vitro. The aim of this study was therefore to evaluate how closely short-term spheroid cultures of primary colorectal cancer cells resemble the original tumour. Colorectal cancer cells were isolated from human tumour tissue and cultured as spheroids. Spheroid cultures were established with a high success rate and remained viable for at least 10 days. The spheroids exhibited significant growth over a period of 7 days and no difference in growth rate was observed for spheroids of different sizes. Comparison of spheroids with the original tumour revealed that spheroid culture generally preserved adenocarcinoma histology and expression patterns of cytokeratin 20 and carcinoembryonic antigen. Interestingly, spheroids had a tendency to resemble tumour protein expression more closely after 10 days of culture compared to 3 days. Chemosensitivity screening using spheroids from five patients demonstrated individual response profiles. This indicates that the spheroids maintained patient-to-patient differences in sensitivity towards the drugs and combinations most commonly used for treatment of colorectal cancer. In summary, short-term spheroid culture of primary colorectal adenocarcinoma cells represents a promising in vitro model for use in personalized medicine.

Superficial scrapings from breast tumors is a source for biobanking and research purposes

Breast cancer is a unique tumor disease in terms of the stringent requirement of predictive biomarker assessments. As recommended by current international guidelines, the established markers consist of estrogen receptor (ER), progesterone receptor, human epidermal growth factor and Ki67, and are primarily analyzed by immunohistochemistry. However, new diagnostic methods based on microarray or next-generation sequencing on DNA and mRNA level are gaining ground. These analyses require fresh-frozen tumor tissue that is generally not available from tumors <10 mm in diameter, comprising almost 25% of all resected breast cancer at our department. We here present a simple and standardized method to generate material from small tumors without risking the histopathological examination. Furthermore, we show that the quality of this material is sufficient for subsequent analysis on mRNA, DNA, and epigenetic level. We were also able to use this method for isolation and expansion of cancer stem cells from the majority of tumors. Consequently, researches can be provided with clinically relevant material for translational studies. In conclusion, this method opens up a new possibility for usage of valuable fresh tumor material for research purposes, biobanking, and next-generation sequencing.

Colostrogenesis: candidate genes for IgG1 transcytosis mechanisms in primary bovine mammary epithelial cells

Bovine colostrogenesis is distinguished by the specific transfer of IgG1 from the blood to mammary secretions. The process has been shown to be initiated by hormones and occurs during the last weeks of pregnancy when steroid concentrations of estradiol (E2 ) and progesterone (P4 ) are highly elevated. Rodent intestinal uptake of immunoglobulin G is mediated by a receptor termed Fc fragment of IgG, Receptor, Transporter, alpha (FcGRT) and supported by light chain Beta-2-Microglobulin (β2M). We hypothesized that steroid hormone treatments (E2 and P4 ) of bovine mammary epithelial cells in vitro would induce up-regulation of IgG1 transcytosis candidate gene mRNA expression suggesting involvement in IgG1 transcytosis. Two different primary bovine mammary epithelial cell cultures were cultured on plastic and rat tail collagen and treated with hormonal combinations (steroids/lactogenic hormones). Evaluated mRNA components were bLactoferrin (bLf: a control), bFcGRT, β2M, and various small GTPases; the latter components are reported to direct endosomal movements in eukaryotic cells. All tested transcytosis components showed strong expression of mRNA in the cells. Expression of bFcGRT, bRab25 and bRhoB were significantly up-regulated (p < 0.05) by steroid hormones. bRab25 and bRhoB showed increased expression by steroid treatments, but also with lactogenic hormones. Analysis for the oestrogen receptor (ER) mRNA was mostly negative, but 25% of the cultures tested exhibited weak expression, while the progesterone receptor (PR) mRNA was always detected. bRab25 and bRhoB and likely bFcGRT are potential candidate genes for IgG1 transcytosis in bovine mammary cells.

Characterization of human breast cancer epithelial cells (HBCEC) derived from long term cultured biopsies

INTRODUCTION

For a more individualized therapeutic approach we explored a protease-free method to culture primary cells from breast cancer biopsies.

METHODS AND RESULTS

Tumor tissue from breast cancer patients after surgery was cultured ex vivo without enzymatic digestion for more than one year and revealed the continuous outgrowth of adherent and proliferating primary cell populations. Immunofluorescence staining of these human breast cancer-derived epithelial cells (HBCEC) and quantification by flow cytometry revealed nearly exclusively cytokeratin-expressing cells. Analysis of surface markers during long term tumor culture of primary HBCEC (more than 476d) demonstrated a prominent expression of CD24, CD44 and MUC1 (CD227). According to aging markers, expression of senescence-associated beta-galactosidase revealed little if any positive staining in a primary tumor-derived HBCEC population after 722d in culture, whereas the majority of normal human mammary epithelial cells (HMEC) demonstrated senescent cells already after a culture period of 32d. In this context, HBCEC populations derived from a tumor culture after 152d and 308d, respectively, exhibited a significant telomerase activity, suggesting continuous proliferative capacity. Treatment with several chemotherapeutic compounds and their combinations revealed distinct cytotoxic effects among HBCEC from different breast cancer patients, indicating an individualized response of these tumor-derived primary cells.

CONCLUSION

The protease-free outgrowth of primary HBCEC offers a patient-specific approach to optimize an individually-designed cancer therapy. Moreover, HBCEC from long term breast tumor tissue cultures resemble tumor cell-like properties by an intact ECM formation and a stable cell surface protein expression providing a reproducible screening platform to identify new biomarkers and to test new therapeutics in individual tumor samples.

Alteration of expression levels of the oxidative phosphorylation system (OXPHOS) in breast cancer cell mitochondria

Mitochondria are dynamic intracellular organelles playing a central role in cell metabolism by generating ATP, through the oxidative phosphorylation system (OXPHOS). Altered mitochondrial functions have been identified as causative or contributing factors in some degenerative diseases and are becoming crucial to understanding cancer mechanisms. We report on distinct expression differences between mitochondria of normal and breast-infiltrating ductal carcinoma (IDC) cells. Mitochondria isolated from HMC (human mammary carcinoma) and HMEC (human mammary epithelial cell) cultures were assayed for expression levels of the multi-protein OXPHOS complexes using Western blot and densitometric analyses. Depressed expression levels were detected for all HMC OXPHOS complexes. Drastic signal reduction was observed for the succinate-dehydrogenase complex II iron-sulphur protein SDH-B (3.38%), while decreasing was reported for the NADH-ubiquinone oxidoreductase complex I Fe-S protein 3 NDUFS3 (32.78%) and the ubiquinol-cytochrome c reductase complex III protein 2 UQCRC2 (50.34%). A significant signal dropping was detected for the ATP-synthase complex V F(1)beta subunit (18.07%). For the cytochrome-oxidase complex IV (CO), near-depletion of the mitochondrial-encoded COI (4.37%) and no apparent variation of the COIV (97.26%) subunits were observed. CO and ATP-synthase were also assayed by cryo-immunoelectron microscopy (CIEM) on unfractionated HMC and HEMC cell mitochondria. COI and F(1)beta differential expression, invariance of COIV levels were corroborated, while HMC mitochondria morphology deterioration was highlighted. MitoTracker Red and fluorescence immunolabelling merging confirmed CIEM data. MitoTracker Red and Green co-staining showed mitochondria membrane property modulation. These data describe bioenergetic and phenotypic alterations of IDC cell mitochondria, possibly providing new cancer hallmarks.

Myoepithelial cells: autocrine and paracrine suppressors of breast cancer progression

Host cellular paracrine regulation of tumor progression is an important determinant of tumor biology but one cell that has been ignored in this regulation is the myoepithelial cell. Myoepithelial cells surround normal ducts and precancerous lesions, especially of the breast and form a natural border separating proliferating epithelial cells from proliferating endothelial cells (angiogenesis). Myoepithelial cells may thus negatively regulate tumor invasion and metastasis. Whereas epithelial cells are susceptible targets for transforming events, myoepithelial cells are resistant. Therefore, it can be said that myoepithelial cells function as both autocrine as well as paracrine tumor suppressors. Our laboratory has found that myoepithelial cells secrete a number of suppressor molecules including high amounts of diverse proteinase inhibitors and angiogenic inhibitors but low amounts of proteinases and angiogenic factors compared to common malignant cell lines. This observation has been made in vitro, in mice, and in humans and suggests that myoepithelial cells exert pleiotropic suppressive effects on tumor progression. The gene expression profile of myoepithelial cells may explain the pronounced anti-invasive and anti-angiogenic effects of myoepithelial cells on carcinoma cells and may also account for the reduced malignancy of myoepithelial tumors, which are devoid of appreciable angiogenesis and invasive behavior.

Mitogenic properties of insulin-like growth factors I and II, insulin-like growth factor binding protein-3 and epidermal growth factor on human breast stromal cells in primary culture

Insulin-like growth factors I and II (IGF-I and IGF-II) are growth factors implicated in both normal mammary gland development and breast cancer. We have previously reported on the effects of components of the IGF system on breast epithelial cells. Since data suggests that stromal-epithelial interactions play a crucial role in breast cancer, we have now investigated the mitogenic properties of IGF-I, IGF-II, insulin-like growth factor binding protein-3 (IGFBP-3) and epidermal growth factor (EGF) on human breast stromal cells in primary culture. We show that, under serum-free conditions, stromal cells are stimulated to grow in response to IGF-I and IGF-II in a dose-dependent manner. IGF-I and EGF, a potent stimulator of human breast epithelial cell growth in primary culture and also associated with breast cancer, appear to stimulate stromal cell growth in a synergistic manner. IGFBP-3 does not inhibit the stimulation of growth by IGF-I, or IGF-I plus EGF. However, IGFBP-3 does inhibit the stimulation of growth by IGF-II. In contrast to our previous results with human breast epithelial cells, IGFBP-3 does not have an IGF-independent inhibitory effect on stromal cell growth. This study is the first to address the effects of IGF-I, IGF-II and IGFBP-3 alone and in combination with EGF on human breast stromal cell growth in primary culture. Characterizing the role of the IGF system in both normal breast epithelial cells and stromal cells will aid in our understanding of the mechanisms behind the role of the IGF system in breast cancer.

Effects of estradiol and tamoxifen on proliferation of human breast cancer cells and human endometrial cells

The effects of estradiol and tamoxifen on the proliferation of estrogen receptor positive cells and the relationship between the tamoxifen tolerance and cell origin were investigated. The tissues of human endometrium and breast cancer were randomly selected following dissection for primary cell culture. After the breast cancer cells and endometrial cells were treated with 1 x 10(-8) mol/L estradiol and/or 1 x 10(-6) tamoxifen, 3H-labelled thymine nucleotide was used to trace the kinetics of cell proliferation. There was no significant difference in the inhibition on the human endometrial cells between tamoxifen-treated group (6.3%) and control group (6.4%), but tamoxifen could significantly inhibit the proliferation of the human breast cancer cells (45.84%) as compared with control group (52.72%). Moreover, tamoxifen could significantly stimulate the proliferation of tamoxifen resistant breast cancer cells (9.64%) as compared with control group (6.32%). Estradiol could significantly stimulate the proliferation of all the three kinds of cells as compare with control group. The combined use of estradiol and tamoxifen could inhibit the proliferation of the endometrial cells and breast cancer cells as compared with estradiol used alone, but on the tamoxifen resistant breast cancer cells, they could more significantly stimulate the proliferation than E2. It was concluded that E2 could stimulate the proliferation of these three kinds of cells. However, the inhibitive effects of tamoxifen on the proliferation of these cells were dependent on the estradiol.

Breast cancer cell lines: friend or foe?

The majority of breast cancer research is conducted using established breast cancer cell lines as in vitro models. An alternative is to use cultures established from primary breast tumours. Here, we discuss the pros and cons of using both of these models in translational breast cancer research.

Mitogenic properties of insulin-like growth factors I and II, insulin-like growth factor binding protein-3 and epidermal growth factor on human breast epithelial cells in primary culture

Insulin-like growth factor-I (IGF-I) and insulin-like growth factor-II (IGF-II) are growth factors implicated in mammary gland development and are believed to be involved in breast cancer. However, the interactions between components of the IGF system and breast epithelial cells, which give rise to breast cancer, are not well understood. We have investigated the mitogenic properties of IGF-I, IGF-II, IGF binding protein-3 (IGFBP-3) and epidermal growth factor (EGF) on human breast epithelial cells (HBEC) in primary culture. We show that, under serum-free conditions, HBEC are stimulated to grow in response to IGF-I and IGF-II in a dose-dependent manner. IGF-I and EGF, a potent stimulator of HBEC growth in primary culture and also associated with breast cancer, appear to stimulate HBEC in a synergistic manner. IGFBP-3 inhibits the stimulation by IGF-I, IGF-II and IGF-I plus EGE In addition, it appears that IGFBP-3 has an inhibitory effect on HBEC growth that is IGF-independent. This study is the first to address the effects of IGF-I, IGF-II and IGFBP-3 alone and in combination with EGF on HBEC growth in primary culture. Characterizing the role of the IGF system in normal breast biology is significant because the system has been implicated in breast cancer and a number of the anti-estrogens used in treatment are believed to function through the IGF system.

Intracellular flow cytometric analysis of primary cultured breast tumor cells

Cell lines are traditionally used as tools for in vitro studies of breast cancer. It is highly debatable however, because of the genetic drift that occurs in such long term cultures how representative these cell lines are of breast cancer in vivo. For this reason primary cultures are generally regarded as a better model. Here we have used a primary culture technique (Int. J. Cancer, 66 (1996) 551; Br. J. Cancer, 78 (1998) 1421) to obtain primary breast cancer cells from 13 breast cancer biopsies. We then describe the development and use of methodology to confirm the purity of the cultures. The acquisition of a highly pure population of epithelial cells was confirmed by flow cytometric analysis of intracellular vimentin and cytokeratin 19. The methodology described will have many applications in studies requiring a highly pure population of epithelial breast cancer cells, as well as wide use in other cancers.

Altered regulation of cyclin G in human breast cancer and its specific localization at replication foci in response to DNA damage in p53+/+ cells

Cyclin G, a recent addition to the cyclin family, was initially identified in screens for new src kinase family members and soon thereafter by differential screening for transcriptional targets of the tumor suppressor gene, p53. We have identified cyclin G as being overexpressed in breast and prostate cancer cells using differential display polymerase chain reaction screening. We demonstrate here that cyclin G is overexpressed in human breast and prostate cancer cells and in cancer cells in situ from tumor specimens. Cyclin G expression was tightly regulated throughout the cell cycle in normal breast cells, peaking at the S and G2/M phases of the cell cycle with lower levels in G1. The cell cycle-dependent expression was absent in breast cancer cells. Following DNA damage in normal p53+/+ cells, cyclin G is triggered to cluster in discrete nuclear DNA replication foci that contain replication-associated proteins such as proliferating cell nuclear antigen (PCNA). While p53-/- cells displayed a faint cyclin G nuclear staining pattern, there was no increased expression and no change in distribution of the staining pattern after DNA damage. The specific subcellular localization of cyclin G at DNA replication foci provides an additional link between p53-mediated growth arrest and cell cycle regulation and suggests that cyclin G may act as an effector of p53-mediated events by functional association with replication foci protein(s).

Short-term primary culture of epithelial cells derived from human breast tumours

As experimental models for breast cancer, most studies rely on established human breast cancer cell lines. However, many of these lines were established over 20 years ago, many from pleural effusions rather than the primary tumour, so the validity of using them as representative models is questionable. This paper describes our experiences, over a 3-year period, in establishing short-term epithelial-cell-enriched preparations from primary breast tumours based on differential centrifugation followed by culture in selective media. Epithelial cells were successfully cultured from 55% of samples, but culture success did not appear to be correlated with tumour histology, stage, grade or node status. Epithelial cell-enriched cultures were immunopositive for broad-spectrum cytokeratin and epithelial membrane antigen (EMA). Positivity for keratin 19 confirmed that the cultures contained tumour-derived cells, which additionally showed significantly higher activity of the reductive pathway of the steroid-converting enzyme 17beta-hydroxysteroid dehydrogenase type I. That the cultures contained tumour and not normal epithelial cells was further substantiated by the complete absence of the calmodulin-like gene NB-1 in tumour-derived cultures; this is only associated with normal breast epithelia. Eighty-five per cent of cultures established from oestrogen receptor (ER)-positive tumours expressed ER in vitro; this was functional in 66% of cultures, although ER-positive phenotype was gradually lost over time. In conclusion, epithelial cells can be isolated and maintained as short-term cultures from primary breast tumours irrespective of histopathological or clinical details, providing a model system with a greater biological and clinical relevance than breast cancer cell lines.

Activity and gene expression of 17beta-hydroxysteroid dehydrogenase type I in primary cultures of epithelial and stromal cells derived from normal and tumourous human breast tissue: the role of IL-8

17Beta-hydroxysteroid dehydrogenase (17-HSD) type I is present and active in most breast cancer cell lines where it modulates local estrogen availability. Currently no information is available on its expression in primary cultures. We have quantitatively determined the cellular localisation of both enzyme activity and expression of the 17-HSD type I gene using a series of primary epithelial and stromal cells derived from normal and tumourous breast. Regulation of 17-HSD type I by IL-8 in tumour-derived cultures was also studied. Reversible 17-HSD activity was observed in most samples. In cultures derived from normal breast, the oxidative pathway predominated by up to 51-fold in epithelial and 28-fold in stromal cells. In tumour-derived cultures, the reductive pathway predominated by up to 24-fold in epithelial and 20-fold in stromal cultures, with no preferred direction in the remaining samples. Expression of the 17-HSD type I gene was determined by quantitative RT-PCR. Although this was constitutively expressed by all samples from both tissue types, significantly higher levels of the gene were observed in tumour-derived cultures (P = 0.008, epithelial; P < 0.0001 stromal vs corresponding normal culture). IL-8 upregulated gene expression in epithelial cells but it was downregulated in stroma. This was reflected in 17-HSD type I activity. Thus, 17-HSD type I is constitutively expressed and active in normal and tumourous breast and can be regulated by IL-8.

Phenotypic and functional characterization in vitro of a multipotent epithelial cell present in the normal adult human breast

The developmental relationships between the different mammary epithelial cell lineages in the human mammary gland are not well defined. To characterize human breast epithelial cells (HBEC) with progenitor activity, we used flow cytometry and single cell sorting to analyze the distribution of cellular phenotypes in primary cultures of reduction mammoplasties and their associated ability to generate colonies in 2-dimensional (D) and 3-D (collagen gel) culture systems. This approach allowed two distinct types of HBEC progenitor populations to be distinguished on the basis of their differential expression of the MUC-1 glycoprotein, CALLA/CD10 and epithelial-specific antigen (ESA). The first type of progenitor, which is enriched in the MUC-1+/CAL-LA-/ESA+ subpopulation, generated colonies of tightly arranged cells in 2-D cultures and small alveolar-like colonies with a central lumen when cultured in a collagen matrix. The cells produced in the colonies and derived from these MUC-1+/CALLA-/ESA+ progenitors were found to express typical luminal epitopes (keratin 8/18, keratin 19, MUC-1, ESA) and showed low levels of expression of myoepithelial epitopes (keratin 14 and CD44v6). The second type of progenitor, which is present in the MUC-1-to +/-/CALLA +/- to +/ESA+ subpopulation, generated mixed colonies of both luminal and myoepithelial cells when seeded in 2-D and 3-D cultures. In 2-D cultures, the centrally located cells exhibited a luminal morphology and expressed ESA, but were heterogeneous in their expression of MUC-1. Radiating from the periphery of these ESA+ HBEC were highly refractile ESA- teardrop-shaped myoepithelial-like cells. When cultured in a collagen matrix, these bipotent progenitors generated large branched colonies composed of a heterogeneous population of cells, with some of the progeny cells expressing luminal epitopes (keratin 8/18, keratin 19 and MUC-1) and others expressing myoepithelial epitopes (keratin 14 and CD44v6). A third type of progenitor, which became apparent is passaged HBEC cultures and was enriched in the MUC-1-/CALLA+/ESA- subpopulation, was found to generate colonies of cells with an exclusively myoepithelial phenotype. These results provide definitive evidence for the existence of multilineage HBEC progenitors in normal adult human mammary tissue. The phenotypic profile of these cells suggest that these multilineage progenitors are a relatively undifferentiated cell since they express low levels of MUC-1 and that they have a luminal location within the mammary epithelium since they are ESA+. Furthermore, we suggest that the MUC-1+/CALLA-/ESA+ and the MUC-1- to +/-/CALLA +/- to +/ESA+ progenitors we have identified and characterized are candidate in vivo alveolar and ductal progenitors, respectively.

Correlation of CD44 expression with proliferative activity of normal human breast epithelial cells in culture

A number of studies have shown that certain variant isoforms of CD44 are overexpressed in human breast cancer, suggesting their use as indicators of the presence of malignant cells. We now show that CD44 isoform mRNA and protein expression is upregulated in normal human breast epithelial cells (HBEC) when these cells are stimulated to proliferate in culture. Reverse transcription-PCR analysis of cultured normal HBEC revealed complex patterns of CD44 mRNA expression that were indistinguishable from patterns previously shown to be characteristic of tissue samples containing malignant HBEC. CD44v6-expressing cells were identified in cultures generated from FACS-purified populations of either normal luminal (CALLA-MUC-1+) or myoepithelial (CALLA+MUC-1-) cells, even though immunohistochemical analysis of normal breast tissue sections confirmed CD44v6 expression to be limited to the myoepithelium in vivo. Increased expression of both CD44v mRNA and protein in cultured populations of normal HBEC was shown to correlate positively with the proportion of cells that were proliferating (Ki-67+) independent of cell density. These results indicate that activation of CD44 variant isoform expression in HBEC occurs as a normal response to factors that stimulate their proliferation and suggests caution in the use of this marker to identify malignant cells.

Isolation and analysis of different subpopulations of normal human breast epithelial cells after their infection with a retroviral vector encoding a cell surface marker

The use of gene transfer procedures has greatly facilitated the investigation of cell lineage relationships and other developmental processes in a variety of primary tissues. In this report we described the infection and selection of primary human breast epithelial cells using retroviral vectors (Jzen-HSA-NEO and MSCV-HSA.NEO) containing the complete 228 bp coding sequence of a murine cell surface marker (Heat Stable Antigen, HSA) as well as the neomycin resistance (neo(r)) gene. Expression of the transduced HSA gene was detectable using either flow cytometry or immunohistochemistry after staining cells with an anti-murine HSA-specific antibody (M1/69). Expression of the transduced neo(r) gene conferred resistance to G418. In initial experiments with the MCF-7 breast cancer cell line, continued expression of both markers was demonstrated in a high proportion of cells for at least 4 weeks after their infection by positive M1/69 staining of cells that had been selected by prior incubation in G418. Evidence of gene transfer to early stage (< 9 days old) primary cultures of normal human breast epithelial cells (15 experiments with cells from 12 normal individuals) was also obtained using an infection protocol in which these calls were exposed to helper-free viral supernatants (2 incubations, 4 to 6 hr each) after being subcultured for 12 to 18 hr to increase their rate of proliferation. The presence of 5-50% (mean = 26%) HSA+ cells was demonstrated in these experiments within 5 days after their infection and the HSA+ populations included both myoepithelial and luminal phenotypes. The transduced (HSA+) cells within both of these subpopulations could also be separately isolated by FACS and subcultured. These results should provide an important starting point for future studies of genetically modified or marked primary human breast epithelial cell populations.

Separated human breast epithelial and myoepithelial cells have different growth factor requirements in vitro but can reconstitute normal breast lobuloalveolar structure

In order to investigate the specific factors controlling the growth of normal breast cell types, purified populations of human breast epithelial and myoepithelial cells from reduction mammoplasties were grown in primary culture in three defined media and their response to foetal calf serum (FCS), epidermal growth factor (EGF) and basic fibroblast growth factor (FGF2) measured using MTT growth assays. Epithelial and myoepithelial cells differed markedly in their growth requirements. Whereas epithelial cell survival was dependent on the presence of FCS, myoepithelial cell growth was dramatically inhibited by serum. EGF and FGF2 were mitogenic for epithelial cells but not myoepithelial cells, the addition of insulin being the only essential supplement required for myoepithelial cell growth. Heparin inhibited FGF2-stimulated epithelial cell growth but also basal myoepithelial cell proliferation and this inhibition could be overcome by the addition of EGF. Neutralizing antibodies to EGF also inhibited basal myoepithelial cell growth. This suggests the possibility of an autocrine role for a heparin-binding member of the EGF family in the growth of myoepithelial cells. Purified cells combined to form lobuloalveolar structures when incubated in a reconstituted basement membrane matrix (Matrigel) in the presence of EGF and FGF2.

Growth requirements and neoplastic transformation of two types of normal human breast epithelial cells derived from reduction mammoplasty

A chemically defined culture medium was developed to support the growth of two distinctly different types of normal human breast epithelial cells (HBEC) derived from reduction mammoplasty. Type I cells expressed luminal epithelial cell markers and were deficient in gap junctional intercellular communication (GJIC), whereas Type II cells expressed basal epithelial cell markers and were efficient in GJIC. In this study, we examined and compared the growth factor and hormone requirements of these two types of cells and a series of cell lines that were obtained by sequential transfection with SV40 DNA (extended lifespan, nontumorigenic), treatment with 5-bromodeoxyuridine (BrdU)/black light (immortal and weakly tumorigenic), and infection of a virus carrying the neu oncogene (highly tumorigenic). Growth of Type I cells was inhibited by withdrawing epidermal growth factor (EGF), hydrocortisone (HC), or insulin (INS) from the culture media, but was enhanced by fetal bovine serum (FBS) supplementation. Growth of Type II cells was inhibited by withdrawal of EGF, HC, or INS from the media, and was inhibited by FBS supplementation. Withdrawal of human transferrin (HT) or 17 beta-estradiol (E2) from the media did not alter the growth of Type I or Type II cells. SV40 transfected Type I cell lines still required EGF, HC, or INS for optimal growth. However, the highly tumorigenic cell line did not show a growth dependence on EGF, HC, or INS but did appear to require HT and 3,3',5-triiodo-D.L. thyronine (T3) for optimal growth. In addition, FBS stimulated the growth of these cell lines. Thus, this study shows that Type I HBEC are distinctly different from Type II HBEC in growth response to FBS and that neoplastically transformed Type I cells could become growth factor and hormone independent.

Selective growth of freshly isolated human breast epithelial cells cultured at low concentrations in the presence or absence of bone marrow cells

In this study, we show that conditions previously found to promote the selective growth of human breast epithelial cells (HBEC) in serum-free primary cultures established from normal or malignant tissue can be extended to cultures initiated at low seeding densities (< 5000 cells/cm2). The epithelial nature of the cells produced was documented by their positive staining with antibodies specific for keratins 8, 14, and 18, and 2 antibodies that recognize epithelial-specific antigens (Ber-EP4 and HB8630). HBEC growth was not affected, either positively or negatively, by the use of a medium containing a combination of fetal calf and horse serum, which promotes the growth of many types of stromal cells and associated hematopoietic precursors, or by the inclusion in the initial cell suspension of marrow cells at HBEC to marrow cell ratios typical of bone marrow samples from patients with metastatic breast cancer. The presence of fibroblast feeders from a variety of sources enhanced the growth of HBEC to different degrees. In cultures initiated with low numbers of cells obtained from samples of breast carcinoma, HBEC growth was generally reduced by comparison to cultures of normal HBEC. With the detection methods used, it was not possible to determine the extent to which this decreased growth was due to a reduced frequency of malignant HBEC with in vitro precursor activity, or the presence of reduced numbers of residual normal HBEC precursors, or both. However, preliminary data indicate that this approach also allows the detection of some breast carcinoma cells with proliferative ability that are present in the marrow or pleural effusions of some breast cancer patients. These studies demonstrate the feasibility of detecting normal and malignant HBEC with growth potential when these are cultured at low density and/or as rare contaminants of marrow cell suspensions, and provide a starting point for their further characterization.

The effects of cyclosporin A, tamoxifen, and medroxyprogesterone acetate on the enhancement of adriamycin cytotoxicity in primary cultures of human breast epithelial cells

Adriamycin (Adr), the single most active agent used in the treatment of breast cancer, may become ineffective as treatment progresses due to the development of multidrug resistant (MDR) tumors. A major mechanism associated with MDR is increased P-glycoprotein (Pgp) expression. This study examined the abilities of the anti-estrogen tamoxifen (TAM) and the progestin medroxyprogesterone acetate (MPA) as well as cyclosporin A (CsA), a known resistance modifier, to enhance the cytotoxic effects of Adr on human breast epithelial cells (HBEC) in primary culture. Pgp and estrogen receptor (ER) expression were determined in each of the cultures by immunocytochemical assays using the monoclonal antibodies C219 and H222 Sp gamma, respectively. The Adr-sensitive, Pgp-, ER+ MCF-7 cell line and the Adr-resistant, Pgp+, ER- MCF7-AdrR cell line were used as controls. Primary cultures were categorized as HBEC from tissues with or without previous chemotherapy. Pgp was detected in 1 of the 15 cell cultures from tissues without previous chemotherapy and in 5 of the 6 cell cultures from tissues previously exposed to chemotherapy. Incubation with either CsA or MPA plus Adr enhanced Adr toxicity in Pgp+ but not Pgp- cell cultures, whereas TAM had no effect on the sensitivity of any of the cultures. Of the 21 primary cultures of HBEC, 3 were ER+. There was no correlation between the enhancement of Adr cytotoxicity and ER status. The data suggest that MPA as well as CsA may be useful as modifying agents in overcoming Pgp-associated multidrug resistance.

A comparative study of cytokine gene transcripts in normal and malignant breast tissue and primary cell cultures derived from the same tissue samples

Using a differential centrifugation method followed by culture in selective medium, we have successfully isolated and maintained individual epithelial and stromal cells from normal (n = 10) and malignant (n = 6) human breast tissue and characterised their phenotype by immunocytochemistry. Further, we have studied expression of the cytokine genes IL-1beta, IL-6, IL-8 and TNF-beta in each cell fraction by RT-PCR and have compared these results with cytokine gene expression in tissue extracts from which primary cultures were derived. In breast tumours, there was near complete absence of IL-1beta in both whole tissue and cell fractions, and in normals it was present in only 3/10 tissue preparations, with increased expression in stromal (6/10) and epithelial (5/10) cell samples. IL-6 was constitutively expressed in all tumour-derived breast tissue samples but down-regulated in tumour cell cultures, with the opposite result in normal breast. Near identical levels of IL-8 expression were found throughout each preparation, irrespective of tissue origin. TNF-beta was expressed in all normal tissue samples, in 9/10 epithelial preparations but in only 6/10 stromal preparations. In tumours, TNF-beta was associated predominantly with whole tissue or stromal samples, with reduced expression in epithelial preparations. Our data confirm that primary cultures of normal and malignant human breast tissue can be successfully separated into epithelial and mesenchymal cell populations and their phenotype can be maintained in culture for up to 30 days. However, this cellular separation does alter the cytokine profiles; therefore, experimental findings with isolated cells should be treated with a caveat.

Human breast cancers respond to growth factors in vivo but not in vitro

Growth response of human breast cancer cells to epidermal growth factor (EGF) and transforming growth factor-alpha (TGF-alpha) was tested both in culture and in vivo in nude mice. Human breast cancer cells were obtained from palpable tumors resulting from xenografted primary breast cancers in nude mice. In collagen gel culture, the breast cancer cells grew autonomously as expanding spherical masses of loosely adherent cells in the basal medium and the supplementation of growth factors had no additional stimulatory effect. To determine whether this in vitro response is reflected in vivo, the collagen gel embedded human breast cancer cells were transplanted into athymic nude mice and the growth response to EGF was studied in vivo. In contrast to the situation in vitro, exogenous EGF was growth promoting in vivo. Our results demonstrate the importance of the combined in vitro-in vivo approach in studying physiologically relevant growth regulation. In addition, the use of collagen gel embedded human breast cancer cells for transplantation studies may more closely model the clinical situation in view of the close histopathological resemblance of the recovered gels to the surgical breast specimens.

Effects of lymphocytes and fibroblasts on the growth of human mammary carcinoma cells studied in short-term primary cultures

Breast carcinomas commonly contain varying amounts of fibrous stroma and infiltrates of lymphoid cells. Dickson and Lippman (Endocrine Rev., 8,29, 1987) have proposed a model of growth regulation in breast cancer involving interactions between stroma and carcinoma cells. This model is based on results obtained with established cell lines. In an effort to bring experimentation closer to the clinical situation we have used short-term primary cultures from human breast cancer in co-cultures with lymphocytes and fibroblasts. Cultures were established in a chemically defined serum-free medium (CDM3). Cell types were characterized on the basis of live morphology and expression of vimentin and keratin 18. A semi-quantitative system was developed for measuring growth of epithelial cells, thus defining two indices: maximal growth index (GI-max) and growth rate (GR). Moderate-to-good growth was obtained from 34 out of 46 carcinoma samples (74%) and 30 out of 38 parallel samples of non-cancerous tissue (79%). Success in culture was negatively correlated with the amount of hard stroma but unrelated to age of patient or clinical status. Malignant epithelium was clearly identified in 12 out of 34 (35%) carcinoma samples. For the evaluation of responses of epithelial cells in co-cultures, the cultures from each sample were ranked according to GI-max.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of estrogen, epidermal growth factor, and transforming growth factor-alpha on the growth of human breast epithelial cells in primary culture

Since 17 beta-estradiol (E2)-stimulated growth in human breast cancer cell lines has been shown to be accompanied by increased production of epidermal growth factor (EGF) and transforming growth factor-alpha (TGF-alpha) and their receptor, we investigated the effects of E2 and these growth factors on the growth of human breast epithelial cells (HBEC) in primary culture. HBEC from normal, benign, and malignant tissues were cultured in serum-free medium [DME:F12(1:1), 5 mg/ml BSA, 10 ng/ml cholera toxin, 0.5 micrograms/ml cortisol, 10 micrograms/ml insulin] in the presence and absence of E2, EGF, and TGF-alpha. Tritiated-thymidine ([3H]TdR) incorporation into DNA was used as a measure of cell growth. E2 did not stimulate growth of any of the cultures at all concentrations examined (10(-9) to 10(-6) M). In contrast, EGF ranging from 1 to 100 ng/ml consistently increased the growth of cells of all three breast tissue types in a dose-dependent manner. The EGF stimulation was inhibited by MAb 528, a monoclonal antibody against the EGF receptor. TGF-alpha was equally or more effective in stimulating proliferation, although its dose-response range was different than that of EGF. E2 and EGF together acted in a synergistic manner in 50% of the samples examined. These studies suggest that E2 can exert effects on HBEC growth via modulation of the cells' response to EGF.