Prolactin induces ERα-positive and ERα-negative mammary cancer in transgenic mice (original) (raw)
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Prolactin-induced mouse mammary carcinomas model estrogen resistant luminal breast cancer
Breast Cancer Research, 2011
Introduction: Tumors that express estrogen receptor alpha (ERα+) comprise 75% of breast cancers in women. While treatments directed against this receptor have successfully lowered mortality rates, many primary tumors initially or later exhibit resistance. The paucity of murine models of this "luminal" tumor subtype has hindered studies of factors that promote their pathogenesis and modulate responsiveness to estrogen-directed therapeutics. Since epidemiologic studies closely link prolactin and the development of ERα+ tumors in women, we examined characteristics of the aggressive ERα+ and ERα-carcinomas which develop in response to mammary prolactin in a murine transgenic model (neu-related lipocalin-prolactin (NRL-PRL)). To evaluate their relationship to clinical tumors, we determined phenotypic relationships among these carcinomas, other murine models of breast cancer, and features of luminal tumors in women.
Differential roles of ERα and ERβ in normal and neoplastic development in the mouse mammary gland
PloS one, 2014
The present experiments were performed to determine the roles of estrogen receptors α and β (ERα and ERβ) in normal and neoplastic development in the mouse mammary gland. In wild-type mice, in vivo administration of estradiol (E) + progesterone (P) stimulated mammary ductal growth and alveolar differentiation. Mammary glands from mice in which the ERβ gene has been deleted (βERKO mice) demonstrated normal ductal growth and differentiation in response to E + P. By contrast, mammary glands from mice in which the ERα gene has been deleted (αERKO mice) demonstrated only rudimentary ductal structures that did not differentiate in response to E + P. EGF demonstrates estrogen-like activity in the mammary glands of αERKO mice: treatment of αERKO mice with EGF + P (without E) supported normal mammary gland development, induced expression of progesterone receptor (PR), and increased levels of G-protein-coupled receptor (GPR30) protein. Mammary gland development in βERKO mice treated with EGF ...
Mammary Gland Development and Tumorigenesis in Estrogen Receptor Knockout Mice
1997
Estrogens are important for the development of the mammary gland and strongly associated with oncogenesis in this tissue. The biological effects of estrogens are mediated through the estrogen receptor (ER),3 a member of the nuclear receptor superfamily. The estrogen/ER signaling pathway plays a central role in mammary gland development, regulating the expression and activity of other growth factors and their receptors. The generation of the ER knockout (ERKO) mouse has made it possible to directly understand the contribution of ER in mammary development and has provided an unique opportunity to study estrogen action in carcinogenesis. A mammary oncogene (Wnt-1) was introduced into the ERKO background to determine if the absence of the ER would affect the development of tumors induced by oncogenic stimulation. The development, hyperplasia, and tumorigenesis in mammary glands from the ERKO/Wnt-1 mouse line are described. These studies provide the impetus to evaluate the effect of other oncogenes in mammary tumorigenesis in the absence of estrogen/ER signaling.
Cancer Research, 2001
We have developed an experimental model of mammary carcinogenesis in which the administration of medroxyprogesterone acetate (MPA) to female BALB/c mice induces progestin-dependent ductal metastatic mammary tumors with high levels of estrogen receptor (ER) and progesterone receptor (PR). Through selective transplants in untreated mice, we have obtained progestin-independent variants, still expressing high levels of ER and PR. Primary cultures of the MPA-induced carcinomas C4-HD and C7-HI were set up, and after 3-4 months, several different cell lines were obtained. Four of these, MC4-L1, MC4-L2, MC4-L3, and MC4-L5 were established from C4-HD and a fifth, MC7-L1, from C7-HI. All cells were of epithelial origin, as demonstrated by electron microscopy and by immunocytochemical identification of cytokeratin and cadherin. In vitro MC4-L1, MC4-L3, and MC4-L5 showed a typical epithelial morphology; when transplanted in vivo, they originated metastatic carcinomas with different degrees of differentiation. MC4-L2 and MC7-L1 deviated from the standard epithelial picture; they disclosed a spindle-shaped morphology in vitro and in vivo gave rise to a biphasic spindle cell/tubular carcinoma and an anaplastic carcinoma, respectively; both lines gave rise to metastases. This differential morphology correlated with a higher degree of aggressiveness, as compared with MC4-L1, MC4-L3, and MC4-L5. ERs and PRs were detected by binding, immunocytochemistry, and Western blot. In vitro, MC4-L2 and MC7-L1 were stimulated by MPA (nM to M) and 17-estradiol (nM and 10 nM); no significant stimulation was observed in MC4-L1, MC4-L3, and MC4-L5 under the same experimental conditions. In vivo, MPA significantly stimulated tumor growth in all epithelioid lines but not in MC4-L2 and MC7-L1. A progestin-dependent growth pattern was confirmed for MC4-L1, MC4-L3, and MC4-L5 in successive transplants, whereas MC4-L2 and MC7-L1 behaved as progestin independent. This is the first description of mouse mammary carcinoma cell lines expressing ER and PR. The different in vitro hormone responses as compared with in vivo and the differential effects of 17estradiol in the parental tumors and in cell lines render these lines useful tools for the in vitro and in vivo study of hormone regulation of tumor growth and metastases.
Journal of Endocrinology, 2009
Epidemiologic studies have demonstrated that increased prolactin exposure raises the risk of invasive ERα positive breast cancer in women. However, the mechanism(s) whereby this occurs, and interactions with estrogen itself in this disease remain poorly understood. In order to investigate the role of ovarian hormones in the disease process, we employed a transgenic model (NRL-PRL) in which transgenic prolactin is directed to mammary epithelial cells by the prolactin-and estrogeninsensitive NRL promoter, mimicking the endogenous prolactin expression within the breast observed in women. This high local exposure leads to mammary lesion development and eventually carcinomas. Ovariectomy shortly after puberty did not alter the incidence or latency of prolactininduced mammary carcinomas, consistent with the independence of prolactin from circulating estrogens as a risk factor for invasive breast cancer in women. However, chronic estrogen administration to ovariectomized NRL-PRL females decreased the latency of both ERα positive and negative tumors. We identified multiple mechanisms that may underlie this observation. Elevated estrogen exposure cooperated with prolactin to increase epithelial proliferation and myoepithelial abnormalities, increasing the incidence of preneoplastic lesions. Critical components of the extracellular matrix secreted by the myoepithelium were reduced with age, and transgenic prolactin raised transcripts for tenascin-C and maspin, both associated with tumor progression and poor prognosis in subclasses of clinical breast tumors. Mammary pERK1/2 and pAkt, but not pStat5, were markedly elevated by local prolactin. Together, these findings indicate that prolactin employs multiple mechanisms to promote mammary tumorigenesis.
Hormonal carcinogenesis in breast cancer: cellular and molecular studies of malignant progression
Breast Cancer Research and Treatment, 1994
We have established and characterized a series of variant cell lines in which to identify the critical factors associated with E2-induced malignant progression, and the acquisition to tamoxifen resistance in human breast cancer. Sublines of the hormone-dependent MCF-7 cell line (MCF7/MIII and MCF7/LCC1) form stable, invasive, estrogen independent tumors in the mammary fat pads of ovariectomized athymic nude mice. These cells retain expression of both estrogen (ER) and progesterone receptors (PGR), but retain sensitivity to each of the major structural classes of antiestrogens. The tamoxifen-resistant MCF7/LCC2 cells retain sensitivity to the inhibitory effects of the steroidal antiestrogen ICI 182780. By comparing the parental hormone-dependent and variant hormone-independent cells, we have demonstrated an altered expression of some estrogen regulated genes (PGR, pS2, cathepsin D) in the hormone-independent variants. Other genes remain normally estrogen regulated (ER, laminin receptor, EGF-receptor). These data strongly implicate the altered regulation of a specific subset or network of estrogen regulated genes in the malignant progression of human breast cancer. Some of the primary response genes in this network may exhibit dose-response and induction kinetics similar to pS2, which is constitutively upregulated in the MCF7/MIII, MCF7/LCC1 and MCF7/LCC2 cells.
Conditional Estrogen Receptor Knockout Mouse Model for Studying Mammary Tumorigenesis
2001
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The challenges of modeling hormone receptor-positive breast cancer in mice
Endocrine-Related Cancer
Estrogen receptor-positive (ER+) tumors account for 70–80% of all breast cancer (BC) cases and are characterized by estrogen dependency for their growth. Endocrine therapies using estrogen receptor antagonists or aromatase inhibitors represent a key component of the standard of care for these tumors. The occurrence of de novo or acquired resistance to estrogen withdrawal represents an important clinical problem, impacting on patient survival. In addition, despite an initially favorable outcome, a part of ER+ BC patients present with disease recurrence locally or at distant sites years or even decades after apparent remission. In vivo models that closely mimic human disease are urgently needed to study the biology of these tumors, investigate the molecular mechanisms underlying endocrine resistance and identify patients at risk of recurrence. Despite the similarities in the overall hormonal regulation of mammary gland development between mice and humans, the majority of the mammary c...
Breast Cancer Research, 2007
Introduction About 70% of breast cancers express oestrogen receptor α (ESR1/ERα) and are oestrogen-dependent for growth. In contrast with the highly proliferative nature of ERαpositive tumour cells, ERα-positive cells in normal breast tissue rarely proliferate. Because ERα expression is rapidly lost when normal human mammary epithelial cells (HMECs) are grown in vitro, breast cancer models derived from HMECs are ERαnegative. Currently only tumour cell lines are available to model ERα-positive disease. To create an ERα-positive breast cancer model, we have forced normal HMECs derived from reduction mammoplasty tissue to express ERα in combination with other relevant breast cancer genes.
PLoS ONE, 2013
Androgen receptor (AR) is commonly expressed in both the epithelium of normal mammary glands and in breast cancers. AR expression in breast cancers is independent of estrogen receptor alpha (ERa) status and is frequently associated with overexpression of the ERBB2 oncogene. AR signaling effects on breast cancer progression may depend on ERa and ERBB2 status. Up to 30% of human breast cancers are driven by overactive ERBB2 signaling and it is not clear whether AR expression affects any steps of tumor progression in this cohort of patients. To test this, we generated mammary specific Ar depleted mice (MARKO) by combining the floxed allele of Ar with the MMTV-cre transgene on an MMTV-NeuNT background and compared them to littermate MMTV-NeuNT, Ar fl /+ control females. Heterozygous MARKO females displayed reduced levels of AR in mammary glands with mosaic AR expression in ductal epithelium. The loss of AR dramatically accelerated the onset of MMTV-NeuNT tumors in female MARKO mice. In this report we show that accelerated MMTV-NeuNT-dependent tumorigenesis is due specifically to the loss of AR, as hormonal levels, estrogen and progesterone receptors expression, and MMTV-NeuNT expression were similar between MARKO and control groups. MMTV-NeuNT induced tumors in both cohorts displayed distinct loss of AR in addition to ERa, PR, and the pioneer factor FOXA1. Erbb3 mRNA levels were significantly elevated in tumors in comparison to normal mammary glands. Thus the loss of AR in mouse mammary epithelium accelerates malignant transformation rather than the rate of tumorigenesis.