[Promoting home support for elderly people with neurocognitive disorders: Caregiver perception of the help-seeking process]. / Favoriser le maintien à domicile des personnes âgées atteintes de troubles neurocognitifs. Perception par les proches aidants de leur processus de recherche d'aide.

BACKGROUND: Caregivers play an essential role in maintaining home care for elderly people with dementia. However, it is difficult for caregivers to target their own needs as well as those of the person with neurocognitive disorders they support on a daily basis. Identifying the needed resources can also be difficult. In order to better assist caregivers in identifying resources needed to support their role, this study aims to understand the factors that influence their help-seeking process. METHODS: This qualitative and descriptive study focuses on the point of view of the main people affected by this problem: caregivers. Eleven caregivers of elderly people with dementia living at home were recruited by convenience sampling. Semi-structured interviews were conducted, and the data were analyzed according to Mast's typology. RESULTS: The factors influencing caregivers help-seeking process were categorized into five themes: 1) service-related (e.g. wait times); 2) personal (e.g. feeling intrusive); 3) experiential (e.g. positive use of a service); 4) relational (e.g. rejection of the elder), and 5) informational (e.g. directed to the right service). CONCLUSION: Caregivers face many challenges in their help-seeking process and want to be more proactively accompanied in a way adapted to their changing needs.

Main-Ion Intrinsic Toroidal Rotation Profile Driven by Residual Stress Torque from Ion Temperature Gradient Turbulence in the DIII-D Tokamak.

Intrinsic toroidal rotation of the deuterium main ions in the core of the DIII-D tokamak is observed to transition from flat to hollow, forming an off-axis peak, above a threshold level of direct electron heating. Nonlinear gyrokinetic simulations show that the residual stress associated with electrostatic ion temperature gradient turbulence possesses the correct radial location and stress structure to cause the observed hollow rotation profile. Residual stress momentum flux in the gyrokinetic simulations is balanced by turbulent momentum diffusion, with negligible contributions from turbulent pinch. The prediction of the velocity profile by integrating the momentum balance equation produces a rotation profile that qualitatively and quantitatively agrees with the measured main-ion profile, demonstrating that fluctuation-induced residual stress can drive the observed intrinsic velocity profile.

Trapped electron mode turbulence driven intrinsic rotation in Tokamak plasmas.

Progress from global gyrokinetic simulations in understanding the origin of intrinsic rotation in toroidal plasmas is reported. The turbulence-driven intrinsic torque associated with nonlinear residual stress generation due to zonal flow shear induced asymmetry in the parallel wave number spectrum is shown to scale close to linearly with plasma gradients and the inverse of the plasma current, qualitatively reproducing experimental empirical scalings of intrinsic rotation. The origin of current scaling is found to be enhanced k(∥) symmetry breaking induced by the increased radial variation of the safety factor as the current decreases. The intrinsic torque is proportional to the pressure gradient because both turbulence intensity and zonal flow shear, which are two key ingredients for driving residual stress, increase with turbulence drive, which is R/L(T(e)) and R/L(n(e)) for the trapped electron mode.

Transforming function of the LSM1 oncogene in human breast cancers with the 8p11-12 amplicon.

Amplification of the 8p11-12 region occurs in 15-20% of breast cancers, but the driving oncogene at this locus has yet to be definitively identified. We mapped the 8p11-12 amplicon in breast cancer cell lines and primary human breast cancers and identified the candidate oncogene human Sm-like protein (hLsm1, LSM1) based on increases in copy number and expression level relative to human mammary epithelial cells. To examine the oncogenic role of LSM1, we overexpressed this gene in MCF10A mammary epithelial cells and inhibited its production in the SUM44 breast cancer cell line, which has a natural amplification and overexpression of LSM1. Our data confirmed that LSM1 is an oncogene from the 8p11-12 amplicon by showing that hLsm1 overexpression induced growth factor-independent proliferation and soft agar colony formation in MCF10A cells, and hLsm1 inhibition in SUM44 cells dramatically reduced soft agar growth. Little is known about hLsm1 function other than its involvement in mRNA degradation; therefore, we used expression microarray analysis to investigate how hLsm1 affects cell transformation in MCF10A and SUM44 cells. We identified numerous genes altered following hLsm1 overexpression common to SUM44 breast cancer cells that play important roles in cell cycle regulation, cell proliferation and other cancer-promoting processes. Future work will continue to characterize these important changes to achieve a more complete understanding of the mechanism of hLsm1's effect on cancer progression.

The flashing Brownian ratchet and Parrondo's paradox.

A Brownian ratchet is a one-dimensional diffusion process that drifts towards a minimum of a periodic asymmetric sawtooth potential. A flashing Brownian ratchet is a process that alternates between two regimes, a one-dimensional Brownian motion and a Brownian ratchet, producing directed motion. These processes have been of interest to physicists and biologists for nearly 25 years. The flashing Brownian ratchet is the process that motivated Parrondo's paradox, in which two fair games of chance, when alternated, produce a winning game. Parrondo's games are relatively simple, being discrete in time and space. The flashing Brownian ratchet is rather more complicated. We show how one can study the latter process numerically using a random walk approximation.

The PHSRN sequence induces extracellular matrix invasion and accelerates wound healing in obese diabetic mice.

The PHSRN sequence of the plasma fibronectin (pFn) cell-binding domain induces human keratinocytes and fibroblasts to invade the naturally serum-free extracellular matrices of sea urchin embryos. The potency of acetylated, amidated PHSRN (Ac-PHSRN-NH(2)) is significantly increased, making it more active on a molar basis than the 120-kDa cell-binding domain of pFn. Arginine is important to this activity because PHSAN and PHSEN are inactive, as is a randomized sequence peptide, Ac-HSPNR-NH(2). One treatment with Ac-PHSRN-NH(2) stimulates reepithelialization and contraction of dermal wounds in healing-impaired, obese diabetic C57BL6/KsJ db/db mice. Wound closure is equally rapid in treated db/db and db/+ mice and may be more rapid than in untreated nondiabetic db/+ littermates. In contrast, treatment with either Ac-HSPNR-NH(2) or normal saline (NS) has no effect. Analysis of sectioned db/db wounds shows that, in contrast to treatment with Ac-HSPNR-NH(2) or NS, a single Ac-PHSRN-NH(2) treatment stimulates keratinocyte and fibroblast migration into wounds, enhances fibroplasia and vascularization in the provisional matrix, and stimulates the formation of prominent fibers that may be associated with wound contraction.

Her4 mediates ligand-dependent antiproliferative and differentiation responses in human breast cancer cells.

The function of the epidermal growth factor receptor (EGFR) family member HER4 remains unclear because its activating ligand, heregulin, results in either proliferation or differentiation. This variable response may stem from the range of signals generated by HER4 homodimers versus heterodimeric complexes with other EGFR family members. The ratio of homo- and heterodimeric complexes may be influenced both by a cell's EGFR family member expression profile and by the ligand or even ligand isoform used. To define the role of HER4 in mediating antiproliferative and differentiation responses, human breast cancer cell lines were screened for responses to heregulin. Only cells that expressed HER4 exhibited heregulin-dependent antiproliferative responses. In-depth studies of one line, SUM44, demonstrated that the antiproliferative and differentiation responses correlated with HER4 activation and were abolished by stable expression of a kinase-inactive HER4. HB-EGF, a HER4-specific ligand in this EGFR-negative cell line, also induced an antiproliferative response. Moreover, introduction and stable expression of HER4 in HER4-negative SUM102 cells resulted in the acquisition of a heregulin-dependent antiproliferative response, associated with increases in markers of differentiation. The role of HER2 in these heregulin-dependent responses was examined through elimination of cell surface HER2 signaling by stable expression of a single-chain anti-HER2 antibody that sequestered HER2 in the endoplasmic reticulum. In the cell lines with either endogenously (SUM44) or exogenously (SUM102) expressed HER4, elimination of HER2 did not alter HER4-dependent decreases in cell growth. These results suggest that HER4 is both necessary and sufficient to trigger an antiproliferative response in human breast cancer cells.

Primary culture and serial passage of normal and carcinogen-treated rat mammary epithelial cells in vitro.

A newly developed culture system was used to examine the proliferative potential of rat mammary epithelial (RME) cells in vitro. RME cells were obtained by enzymatic dissociation of mammary tissues of 45- to 50-year-old virgin female LEW rats. The tissues were dissociated to small aggregates (10-50 cells per aggregate) separated from stromal cells and plated at a density of 10(5) cells per 60-mm tissue culture dish. The cells were grown in Ham's medium F12 supplemented with 5% fetal bovine serum, insulin, hydrocortisone, epidermal growth factor, prolactin, progesterone, and cholera toxin. Plating of 10(5) cells as small aggregates resulted in the attachment of 1,000-1,500 aggregates per plate. When grown on tissue culture plastic, approximately 1-2% of these aggregates gave rise to rapidly proliferating epithelial colonies. Individual colonies expanded with a population-doubling time of 24-34 hours and grew for about 3 weeks. Although these cells grew well in primary culture, they were not subculturable. When RME cells were plated onto dishes coated with type I collagen, the number of rapidly proliferating epithelial colonies per dish increased fivefold to tenfold. Cells grown on type I collagen-coated dishes expanded with a population-doubling time of approximately 27 hours and after 2 weeks in primary culture were nearly confluent. Unlike cells grown on plastic, RME cells grown on type I collagen were readily subculturable and serial subculture resulted in the cells undergoing 15-20 population doublings (5-6 passages) before exhibiting any loss of growth potential. Continued feeding of senescent cultures resulted in the emergence of discrete RME cell foci that retained proliferative potential and that eventually developed into rapidly growing cell strains. Exposure of primary cultures to the carcinogen N-methyl-N'-nitro-N'-nitrosoguanidine (CAS: 70-25-7) enhanced the proliferative potential of RME cells in early passages and in later passages either delayed or eliminated the "senescent" phase of cell growth. Carcinogen treatment of RME cells also facilitated the establishment of rapidly growing cell strains with long-term growth potential (greater than 20 passages).

Growth factor synthesis and human breast cancer progression.

Data obtained using long-established human breast cancer cell lines have suggested that autocrine growth factors secreted by the cells are important for their growth in vitro. Such data alone cannot definitively establish a role for autocrine growth factors in human breast cancer cell proliferation in vivo, but they create a paradigm that can be tested by analysis of data obtained with primary breast cancer cells and tissues. This review is aimed at examining experimental data obtained using fresh human breast cancer cells and tissues to determine whether the results obtained are consistent with predictions made by autocrine models of human breast cancer cell proliferation. Conceptually, for autocrine loops to be of primary importance in human breast cancer cell proliferation, breast cancer cells in vivo must 1) synthesize biologically active growth factors that are available to growth factor receptors, 2) synthesize the cognate growth factor receptors, 3) require the specific factors for proliferation, and 4) express the autocrine loop as a pathologic, rather than a physiologic, process. Since the proportion of tumors that express growth factors of a given family is consistently higher than the proportion of tumors that express the cognate receptors, it is likely that growth factor synthesis has an important, nonautocrine role in breast cancer progression as well. Data obtained with primary human breast cancer specimens indicate that growth factors synthesized by breast cancer cells have an important role in tumor development and progression but that these factors act in a true autocrine fashion only in a subset of tumors.

Induction of mammary tumors in virgin female BALB/c mice by single low doses of 7,12-dimethylbenz[a]anthracene.

The induction of mammary tumors in virgin female inbred BALB/c mice after administration of 7,12-dimethylbenz[a]anthracene (DMBA) over a wide range of doses was studied. Mice were exposed at 12 weeks of age to single or multiple doses of DMBA ranging from 0.0025 to 12.0 mg by gastric intubation and were checked regularly for mammary tumors. The experiment was terminated when the mice were 800 days of age. In the dose range of 0.0025--0.125 mg DMBA, the incidence of mammary tumors was dose-dependent. At higher doses, the mammary tumor incidence became less dose-dependent and was nearly independent of doses above the 0.25-mg level. Analysis of the data for the rate of appearance of mammary tumors with age of the animals and for the age at death of non-mammary tumor-bearing animals indicated that in the low dose range induction of mammary tumors was the predominant effect of DMBA exposure, whereas at moderate to high doses the toxic and carcinogenic effects of DMBA on other tissues significantly influenced the final incidence of mammary tumors. Greater than 90% of the tumors that resulted from administration of low doses of DMBA were adenocarcinomas. In contrast, adenocarcinomas and adenoacanthomas were found in approximately equal proportions following administration of high doses of DMBA.

Factors influencing expression of mammary ductal dysplasia in cell dissociation-derived murine mammary outgrowths.

The expression of mammary ductal dysplasia has been shown to be enhanced in mammary outgrowths derived from enzymatically dissociated mammary cells and influenced by the number of cells used to derive the outgrowths. The present study was designed to examine this cell dose effect further and to determine if the developmental state of the outgrowths or the time between carcinogen administration and cell dissociation affects the expression and persistence of the ductal dysplasias. Mammary outgrowths were derived by injecting 10(4) or 10(5) enzymatically dissociated mammary cells into gland-free fat pads of 3-week-old female BALB/c mice. Donor animals were untreated or were exposed to either 7,12-dimethylbenz(a)anthracene or gamma-ray irradiation. The outgrowths were examined at 4.5, 8, 10, or 16 weeks after transplantation, depending on the experiment, and classified as having normal or dysplastic growth. The data indicated that expression of ductal dysplasia was greater in outgrowths derived from 10(4) than from 10(5) cells regardless of the developmental state of the outgrowths. When 24 hr elapsed between carcinogen exposure and cell dissociation, expression of lesions in outgrowths derived from 10(4) cells required active ductal growth, in that lesions that were present in developing outgrowths remodeled and were no longer detectable when the outgrowths completely filled the fat pad. When second-transplant-generation outgrowths were derived from cells of full (non-growing) first-generation outgrowths, ductal dysplasias were reexpressed but, once again, only within developing outgrowths. Increasing the time between carcinogen treatment and cell dissociation, i.e., 6 days or longer, resulted in both increased frequencies of ductal dysplasias and substantial numbers of lesions which persisted within full outgrowths. These results suggested that the acquisition of the altered growth potential which resulted in ductal dysplasias and the ability of these lesions to gain some autonomy from growth-regulatory mechanisms were separate events that occurred at different times after carcinogen treatment.

Detection of ductal dysplasia in mammary outgrowths derived from carcinogen-treated virgin female BALB/c mice.

These studies were undertaken to determine if altered growth potential of mammary epithelial cells could be detected in outgrowths derived from monodispersed mammary cells of virgin female BALB/c mice previously exposed to ionizing radiation or 7, 12-dimethylbenz(a)anthracene (DMBA). Monodispersed mammary epithelial cells were obtained by enzymatic dissociation of mammary tissues of 12-week-old virgin female BALB/c mice. Twenty-four hr prior to cell dissociation, donor animals were exposed to either 100 rads of gamma-ray irradiation, 0.25 mg of DMBA, or 0.075 mg of DMBA. Control donors were untreated. Mammary outgrowths were then derived from these donor cells by injecting either 10(5) or 10(4) cells into the gland-free mammary fat pads of three-week-old virgin female BALB/c mice. Ten weeks after the injection of cells, the outgrowths were examined and classified. Mammary outgrowths were classified either as having a normal ductal architecture or as having ductal dysplasia. Ductal dysplasias were further classified on the basis of an index of severity, which was an arbitrary index based on the number of abnormal ductal structures within each lesion. The data indicated that treatment of donor animals with either gamma-radiation or DMBA increased the frequency of ductal lesions over control levels; however, both the frequency and severity of the lesions depended on the number of cells which were injected into the fat pad. When outgrowths were derived by injection of 10(5) cells into the gland-free fat pads, lesion frequencies in outgrowths from control and treated cells were: 3.3%, control; 15.7%, gamma-rays; 5.3%, 0.25 mg DMBA; in these groups only a few severe lesions were detected. In outgrowths derived from 10(4) cells, less severe lesions (Class I lesions) were common in all groups and occurred in approximately 10 to 15% of the outgrowths. The frequency of severe (Class II and III) ductal dysplasia, however, was increased by treatment in these groups, occurring in 4.5% of control outgrowths in 15.6, 14.9, an 14.3% of the outgrowths derived from donor cells treated with 100 rads gamma-rays, 0.075 mg DMBA, nd 0.25 mg DMBA, respectively. Thus, these data indicated that ductal dysplasias were more common and more severe in outgrowths derived from 10(4) rather than 10(5) cells. The ductal lesions observed in this study resembled both morphologically and histologically ductal abnormalities which have been associated with the pathogenesis of mammary carcinoma in both rats and mice.

Importance of extended growth potential and growth factor independence on in vivo neoplastic potential of primary rat mammary carcinoma cells.

Recently developed culture systems that allow extended growth of normal rat mammary epithelial (RME) cells were used to directly compare the proliferative potentials and growth factor requirements of primary normal and primary neoplastic rat mammary cells. RME cells were obtained from 45- to 55-day-old inbred female Lew rats and rat mammary tumor (RMT) cells from 7,12-dimethylbenz(a)anthracene- or N-nitroso-methylurea-induced mammary carcinomas. To compare the proliferative lifespan of RME and RMT cells, colony forming efficiencies were determined after consecutive passages over a 70-day culture period. Whereas the proliferative potential of RME cells declined with time in culture, RMT cells from five separate mammary carcinomas had colony forming efficiencies that increased with serial passage. By the end of the 70-day culture period, colony forming efficiencies for RMT cells were 100- to 1000-fold higher than those for RME cells. To compare the growth factor requirements for RME and RMT cells, a serum-free culture medium that supports RME cell growth was used and the influence of specific growth factors was examined by deletion experiments. Cells from 5 of 18 primary mammary carcinomas exhibited requirements for insulin, epidermal growth factor, and cholera toxin identical to those of RME cells. In contrast, cells from 9 of 18 tumors expressed independence of one, two, or all three of these factors for growth in serum-free culture. To examine the in vivo growth potential of primary RMT cells, samples of the cell suspensions used to initiate primary cultures were transplanted into the interscapular white fat pads of syngeneic female recipients. Transplantation of cells from growth factor dependent tumors yielded nonneoplastic mammary outgrowths. In contrast, transplantation of growth factor independent tumor cells yielded grossly visible tumors in 100% of the recipients within 4 weeks of transplantation. Thus, our results indicate that cells from all primary mammary carcinomas have dramatically enhanced growth potential in long-term culture relative to RME cells. Furthermore, a subset of these tumors are also independent of growth factors required by RME cells, and expression of growth factor independence is associated with high neoplastic potential in vivo.

Role of growth factor synthesis in the acquisition of insulin/insulin-like growth factor I independence in rat mammary carcinoma cells.

In previous work, we demonstrated that a subset of carcinogen-induced rat mammary carcinomas consists of cells that are independent of growth factors strictly required by normal rat mammary epithelial (RME) cells for long-term growth in serum-free medium. Furthermore, only those tumors that expressed growth factor independence in vitro were serially transplantable in vivo. The present studies were aimed at determining if the independence of insulin (IN)/insulin-like growth factor I (IGF-I) is mediated by autocrine factors synthesized by the rat mammary tumor (RMT) cells. The results of these experiments indicate that IN/IGF-I-independent RMT cells do not synthesize IGF-I that is detectable at the message or peptide level. Both normal and neoplastic cells do, however, secrete IGF-I-binding activity. Conditioned medium, cell lysates, and cell extracts obtained from growth factor-independent cells do not contain growth factor activity that can substitute for IN for growth of IN-dependent RMT cells. Growth factor-independent cells do not express a density dependence for growth in IN-free medium nor do they respond to exogenous IN or IGF-I in low density growth assays. By contrast, growth factor-dependent cells that were rendered IN/IGF-I independent by transfection with an expression vector containing the IGF-I gene secrete IGF-I-like biological activity that is readily detectable and maintain responsiveness to exogenous IN at low densities. Taken together, these results suggest that growth factor-independent RMT cells are truly autonomous of IN/IGF-I for growth and are not synthesizing a growth factor that satisfies their IN/IGF-I requirement in an autocrine manner.

Morphological and histological characteristics of mammary dysplasias occurring in cell dissociation-derived murine mammary outgrowths.

The morphological and histological characteristics of ductal dysplasias that were observed in mammary outgrowths derived from monodispersed mammary cells of carcinogen-treated mice are described. Mammary outgrowths were derived by injecting either 10(4) or 10(5) enzymatically dissociated mammary cells, obtained from control or carcinogen-treated BALB/c mice, into gland-free mammary fat pads of syngeneic hosts. The mammary dysplasias observed varied considerably in morphological and histological characteristics. The majority of the lesions were ductal in origin and were associated with epithelial hyperplasia which ranged from mild hyperplasia, in which only a few extra layers of epithelium were present, to severe hyperplasia, in which the ducts and end buds were occluded and distended with epithelial cells. In addition, papillary and lobular lesions were observed which were also associated with varying degrees of hyperplasia. The range of mammary dysplasias observed in these outgrowths closely resembles that of lesions associated with the pathogenesis of mammary carcinoma in mice, rats, and humans.

Enhanced in vitro proliferation and in vivo tumorigenic potential of mammary epithelium from BALB/c mice exposed in vivo to gamma-radiation and/or 7,12-dimethylbenz[a]anthracene.

Virgin female BALB/c mice were exposed in vivo to whole body gamma-radiation and/or to 7,12-dimethylbenz[a]anthracene (DMBA) p.o. Mammary epithelial cells were isolated and assayed for carcinogen altered cell populations both in vitro by an epithelial focus assay and in vivo by injection into cleared fat pads of syngeneic host mice. Five groups of mice were exposed as follows: (a) sham controls; (b) 50-rad gamma-radiation; (c) 100-rad gamma-radiation; (d) 75 micrograms DMBA; or (e) 50-rad gamma-radiation followed in 1 week by 75 micrograms DMBA. Mammary epithelial cells were isolated and assayed at 24 h and at 1, 4, 16, and 52 weeks after in vivo exposure. Four to 12 mice per treatment per time point were individually assayed. Altered in vitro growth potential was characterized by the proliferation of carcinogen exposed (but not control) cells as epithelial foci which persisted at least 12 weeks in primary culture. Epithelial foci which could then be subcultured at least four times were termed subculturable epithelial foci. Altered in vivo morphogenic potential was characterized by dysplastic or neoplastic growth in host fat pads. With increased time in situ between exposure and assay, cell populations emerged which exhibited both increased in vitro subculturability and enhanced tumorigenic potential including a host response upon injection in vivo. Further, combined radiation and DMBA resulted in higher frequencies of subculturable epithelial foci than either treatment alone. The relevance of these progressive cellular changes to the process of mammary tumor development is discussed.

erbB family receptor expression and growth regulation in a newly isolated human breast cancer cell line.

A new human breast cancer cell line (SUM-52PE), originating from a malignant pleural effusion specimen, that can be cultured under serum-free conditions has been isolated. Experiments were conducted to examine the relationship between expression of the erbB family of growth factor receptors and growth regulation in these cells. SUM-52PE cells are epidermal growth factor receptor negative but express single copy levels of erbB-2 protein. Southern blot analysis indicates that the erbB-2 gene is not amplified in these cells. The cells also express mRNA for both erbB-3 and erbB-4. Phosphotyrosine Western blot analysis of membrane protein obtained from SUM-52PE cells indicates the presence of a constitutively tyrosine phosphorylated M(r) 185,000 protein. Immunoprecipitation, using antibodies to erbB-2 or erbB-3, coupled to phosphotyrosine Western blot analysis indicates that both erbB-2 and erbB-3 are constitutively tyrosine phosphorylated in proliferating SUM-52PE cells. Conditioned medium obtained from SUM-52PE cells does not induce tyrosine phosphorylation of p185erbB-2 in a sensitive indicator cell line, suggesting that an erbB-2 activating factor is not secreted by these cells. However, neu differentiation factor/heregulin (NDF/HRG) mRNA is expressed by the cells, and Western blot analysis of SUM-52PE membrane protein revealed the presence of a M(r) 90,000 immunoreactive NDF/HRG protein. Thus, SUM-52PE cells synthesize a membrane bound form of NDF/HRG that may activate erbB-2 and erbB-3 via a juxtacrine mechanism. The addition of exogenous beta-2-NDF/HRG to the culture medium of SUM-52PE cells yields enhanced tyrosine phosphorylation of p185erbB-2/erbB-3 but has only a small stimulatory effect on the proliferation of these cells. By contrast, an erbB-2 monoclonal antibody that binds to the extracellular domain of erbB-2 is potently mitogenic for these cells. SUM-52PE cells were also found, by phosphotyrosine Western blot analysis, to express an inordinately large number of tyrosine phosphoproteins. Direct measurement of phosphotyrosine phosphatase (PTPase) activity in SUM-52PE cell membrane protein revealed 2-3-fold lower levels of PTPase activity compared to other normal and neoplastic breast epithelial cell lines. Thus, SUM-52PE cells exhibit altered growth phenotypes not identified previously in human breast cancer cells. The constitutive activation of erbB-2 and erbB-3 in these cells, coupled with their low, membrane-associated, PTPase activity are likely to play direct roles in driving proliferation of these breast cancer cells.

Role of epidermal growth factor receptor and STAT-3 activation in autonomous proliferation of SUM-102PT human breast cancer cells.

This report describes the isolation and characterization of a new human breast cancer cell line, SUM-102PT, obtained from a minimally invasive human breast carcinoma. SUM-102PT cells have a near diploid karyotype, and early-passage cells had minor chromosomal abnormalities including a 5, 12 and a 6, 16 reciprocal translocation. The cells were isolated and have been continually cultured in three defined media, one of which contains exogenous epidermal growth factor (EGF). SUM-102PT cells have also been carried in an EGF-free medium supplemented with progesterone. All SUM-102PT cells require EGF receptor (EGFR) activation for continuous growth, because incubation of the cells with EGFR-neutralizing antibodies or with EGFR kinase inhibitors blocks growth of these cells. Southern analysis indicates that the EGFR gene is not amplified in these cells; however, these cells express high levels of EGFR mRNA. Thus, SUM-102PT is representative of a class of human breast cancers characterized by high level EGFR expression in the absence of gene amplification. SUM-102PT cells cultured in EGF-free, progesterone-containing medium express high levels of constitutively active EGFR. Conditioned medium from SUM-102PT cells contains an EGF-like mitogen that binds to a heparin-agarose affinity matrix with high affinity. Northern analysis for various EGF family members indicates that SUM-102PT cells synthesize heparin binding (HB)-EGF mRNA. HB-EGF protein is detectable on the surface of these cells by immunohistochemistry, and SUM-102PT cells are killed by diphtheria toxin, which acts by binding to HB-EGF. Furthermore, HB-EGF antibodies partially neutralize the mitogenic activity of the conditioned medium. Thus, EGFR activation in SUM-102PT cells is mediated, at least in part, by autocrine/juxtacrine stimulation by HB-EGF. SUM-102PT cells also express constitutively active STAT-3 homodimers. Constitutively tyrosine-phosphorylated STAT-3 homodimers were also detected in another breast cancer cell line, MDA468, which has an EGFR amplification and also has constitutive EGFR activity. Thus, SUM-102PT is a new human breast cancer cell line that expresses activated EGFR as a result of an autocrine/juxtacrine interaction with HB-EGF which, in turn, results in activation of STAT-3.

Presence of an insulin-like growth factor I autocrine loop predicts uterine fibroid responsiveness to tamoxifen.

Uterine leiomyoma is an estrogen-responsive tumor, and the present studies examine the ability of the antiestrogen tamoxifen to modulate leiomyoma cell growth. Tamoxifen is an effective form of hormonal therapy for breast cancer, although the mechanism by which tamoxifen inhibits tumor growth is not well understood and may involve mechanisms other than the action of tamoxifen as an estrogen antagonist. Tamoxifen was found to inhibit the proliferation of three of five leiomyoma-derived cell lines (ELT cell lines) in vitro, including an estrogen receptor-negative cell line. The ability of tamoxifen to decrease leiomyoma growth was found to correlate with expression of insulin-like growth factor I (IGF-I) by the tumor cells, suggesting that the inhibitory effects of tamoxifen were associated with expression of this growth factor. The existence of an IGF-I autocrine loop in the cells was investigated, because transcripts for both IGF-I and its cognate receptor were expressed in the tamoxifen-responsive cell lines. An IGF-I RIA demonstrated secreted IGF-I protein in serum-free medium conditioned by the IGF-I-expressing cell line ELT 3, and this same medium supported the growth of IGF-requiring MCF-10A cells, indicating the presence of biologically active IGF-I in the conditioned medium. Exogenous IGF-I stimulated ELT 3 cell proliferation, confirming that this growth factor is mitogenic for leiomyoma cells. IGF-I neutralizing antibody inhibited ELT 3 growth, indicating that the levels of IGF-I produced by the leiomyoma cells were physiologically significant. These data demonstrate the existence of an IGF-I autocrine loop in tamoxifen-sensitive leiomyoma cells, supporting the hypothesis that the presence of an IGF-I autocrine loop predicts uterine fibroid responsiveness to tamoxifen.

Differential isolation of normal luminal mammary epithelial cells and breast cancer cells from primary and metastatic sites using selective media.

The present studies were aimed at determining if the use of a cell culture medium that supports proliferation of human mammary epithelial cells of the luminal lineage would allow routine isolation of breast cancer cells from primary and metastatic tumor specimens. Results obtained with mammary epithelial cells derived from reduction mammoplasty specimens and primary breast carcinomas indicated that growth of cells on type I collagen-coated dishes in Ham's F-12 medium supplemented with insulin, hydrocortisone, epidermal growth factor, cholera toxin, and 5% fetal bovine serum resulted in the growth and serial passage of cells that stained positively for the luminal cell marker cytokeratin 19. By contrast, growth of mammary epithelial cells in a growth factor-supplemented serum-free medium resulted in the emergence of mammary epithelial cell colonies that were uniformly negative for keratin 19. Filter isolation methods were used to isolate individual keratin-19-positive colonies from primary cultures derived from breast cancer specimens. All of the luminal mammary epithelial cells isolated from breast cancer tissues expressed characteristics of normal cells. Keratin-19-positive colonies isolated from several different tumors all grew rapidly for 30 to 60 days in culture and then senesced. Cells were isolated from one tumor that was known to have undergone a loss of heterozygosity at a specific locus in the p53 gene. All colonies isolated from this specimen contained both p53 alleles, which was consistent with their origin from normal luminal cells. Cells were also isolated from one tumor in which the c-erbB2 protein was drastically overexpressed in the neoplastic cells. Once again, keratin-19-positive colonies isolated from this tumor did not overexpress the c-erbB-2 protein. Experiments were then performed with cells derived from pleural effusions and metastatic lymph nodes. Results obtained with these specimens indicated that the growth conditions that support the growth of normal luminal mammary epithelial cells do not support the growth of neoplastic cells. However, the omission of cholera toxin, epidermal growth factor, and type I collagen substratum resulted in the isolation of two long-term cell lines. Both cell lines have population doubling times of approximately 100 h, are hyperdiploid, and stain positively for cytokeratin 19. Thus, culture conditions that support the growth of normal luminal mammary epithelial cells do not, in general, support the growth of breast cancer cells.