Effects of oestradiol and progesterone on the alkaline phosphatase activity of a human endometrial cancer cell-line

G protein-coupled estrogen receptor-selective ligands modulate endometrial tumor growth

Endometrial carcinoma is the most common cancer of the female reproductive tract. GPER/GPR30 is a 7-transmembrane spanning G protein-coupled receptor that has been identified as the third estrogen receptor, in addition to ERα and ERβ. High GPER expression is predictive of poor survival in endometrial and ovarian cancer, but despite this, the estrogen-mediated signaling pathways and specific estrogen receptors involved in endometrial cancer remain unclear. Here, employing ERα-negative Hec50 endometrial cancer cells, we demonstrate that GPER mediates estrogen-stimulated activation of ERK and PI3K via matrix metalloproteinase activation and subsequent transactivation of the EGFR and that ER-targeted therapeutic agents (4-hydroxytamoxifen, ICI182,780/fulvestrant, and Raloxifene), the phytoestrogen genistein, and the “ERα-selective” agonist propylpyrazole triol also function as GPER agonists. Furthermore, xenograft tumors of Hec50 cells yield enhanced growth with G-1 and estrogen, the latter being inhibited by GPER-selective pharmacologic antagonism with G36. These results have important implications with respect to the use of putatively ER-selective ligands and particularly for the widespread long-term use of “ER-targeted” therapeutics. Moreover, our findings shed light on the potential mechanisms of SERM/SERD side effects reported in many clinical studies. Finally, our results provide the first demonstration that pharmacological inhibition of GPER activity in vivo prevents estrogen-mediated tumor growth.

Downregulation of vasohibin-2, a novel angiogenesis regulator, suppresses tumor growth by inhibiting angiogenesis in endometrial cancer cells

The vasohibin-2 (VASH2) gene was originally found to be expressed in infiltrating mononuclear cells of a mouse model of hypoxia-induced subcutaneous angiogenesis. These cells are mobilized from bone marrow to promote angiogenesis. Recently, VASH2 has been demonstrated to be expressed in several types of cancer in which it promotes tumor development through angiogenesis. However, its role in endometrial cancer remains unknown. Using quantitative reverse transcription-polymerase chain reaction (RT-PCR), we found that VASH2 was overexpressed in several human endometrial cancer cell lines, including the HEC50B cell line, which we used to further examine the role of VASH2. Although knockdown of VASH2 with stable transfection of shRNA had little effect on the proliferation of HEC50B cells in vitro, knockdown in an in vivo murine xenograft model inhibited tumor growth by decreasing tumor angiogenesis. In addition, the supernatant from HEC50B cells that expressed VASH2 significantly promoted the proliferation of human umbilical vein endothelial cells. By contrast, knockdown of VASH2 significantly attenuated the proliferative effect. These results indicate that VASH2 contributes to the development of endometrial cancer by promoting angiogenesis through a paracrine mode of action. Consequently, VASH2 may be considered to be a novel molecular target for endometrial cancer therapy.

Development of a mouse model for lymph node metastasis with endometrial cancer

Controlling lymph node metastasis is currently a key issue in cancer therapy. Lymph node metastasis is one of the most important prognostic factors in various types of cancers, including endometrial cancer. Vascular endothelial growth factor-C (VEGF-C) plays a crucial role in lymphangiogenesis, and is implicated to play an important role in lymph node metastasis. To evaluate the role of VEGF-C in lymph node metastasis, we developed an animal model by using an endometrial cancer cell line, HEC1A. This cell line is not invasive by nature and secretes moderate amounts of VEGF-C; intrauterine injection of HEC1A cells into Balb/c nude mice resulted in uterine cancer with lymph node metastasis after 8 weeks. To analyze the contribution of VEGF-C to lymph node metastasis, its corresponding gene was stably introduced into HEC1A cells (HEC1A/VEGF-C), which then produced more than 10 times the amount of VEGF-C. The number of lymph node metastases was significantly higher in HEC1A/VEGF-C cells than in HEC1A cells (3.2 vs 1.1 nodes/animal, respectively). Augmented lymphangiogenesis was observed within tumors when HEC1A/VEGF-C cells were inoculated. These results indicate that VEGF-C plays a critical role in lymph node metastasis, in addition to serving as a platform to test the efficacy of various therapeutic modalities against lymph node metastasis.

HEC-1 cells

HEC-1 cell line was the first in vitro cell line of a human endometrial adenocarcinoma which enabled us to perform research work on the endometrium and endometrial carcinoma at a simplified cellular system, contributing cell and molecular biological studies on endometrial carcinoma. Once a cell line is established, it provides a stable experimental system that facilitates and progresses in the study of the tissues and/or neoplasias from which they are derived. In this article we report how HEC-1 cells have been established and cleared the proposed requirements to characterize the established cell line. Also to show the usefulness of the cell line for research work, once it was established, we illustrate these concepts by recalling results obtained with HEC-1 cells and reviewing the literature on what has been achieved by using these cells.

ETN-1: a new human endometrial carcinoma cell line producing ascites and distant metastases in nude mice

A human carcinoma cell line (ETN-1) has been established from a skin metastasis of a moderately differentiated adenocarcinoma of endometrial origin. The cell line has been so far maintained for 27 months through 55 passages, growing as a monolayer as well as in 3-dimensional clusters with a population doubling time of 72 hr. The number of chromosomes per cell varied from 39 to 107 (average number 61.0 +/- 19.8), with a modal number of 46-48. Seven clonal marker chromosomes were detected. Flow cytometric analysis revealed a population of pseudo-tetraploid cells (DNA index 2.1) next to a pseudo-diploid population (DNA index 1.1). The epithelial character of the cells was confirmed by a positive immunocytochemical reaction using monoclonal antibodies (MAbs) to different keratins, the epithelial cell markers BW 495/36 and HMFG-2, as well as by the presence of many junctional complexes. The tumour cells retained a positive reaction with the anti-ovarian carcinoma OV-TL 3, OV-TL 10 and OC 125 MAbs, although the reaction was markedly diminished in comparison with the original tumour. Tumour cells inoculated subcutaneously in nude mice produced well differentiated adenomatous tumour nodules with formation of glandular lumina and basal lamina. Tumour cells injected intraperitoneally produced malignant ascites and regional as well as distant metastases of adenomatous character.

Cytogenetics of an endometrial adenocarcinoma cell line and its implications

Despite the fact that adenocarcinoma of the endometrium is currently the most common gynecologic malignancy in the United States, few chromosomal studies have been done to date characterizing this disease. HEC-1A, a cell line used by many laboratories as a reference cell line for endometrial carcinoma, has never been subjected to definitive karyotyping. For this reason, with the use of improved banding techniques, this has now been accomplished, and several consistent abnormalities have been identified. There was a marker chromosome formed from an insertion of 2q21, probably representing an insertion of the lacking chromosome 14. In addition, there was a translocation to the telomeric region of 1p; and trisomies of 3, 7, and 17. Many of these abnormalities are known to consistently be associated with other primary malignancies. In addition, the chromosomes in which trisomy is noted carry genes associated with epidermal growth factor and estrogen receptors, which also bear marked homology to known oncogenes. It would appear that further detailed studies of various grades and stages of endometrial carcinoma, as well as histologic types and "precursor lesions," may lead to an understanding of those chromosomal changes associated with disease initiation and progression.

Ornithine decarboxylase activity in human endometrium and endometrial cancer cells

Ornithine decarboxylase (ODC) activities were significantly higher in proliferative endometrium during the estrogen-dominated follicular phase of the menstrual cycle than in secretory endometrium after the formation of the progesterone-secreting corpus luteum. The enzymatic activity was increased about fivefold by renewal of the medium during incubations of endometrial fragments or isolated endometrial glands. Endometrial adenocarcinoma cells (HEC-1, HEC-50), both in monolayers and suspension, also responded to medium renewal by increasing ODC activity about 10-fold after 4 h, with subsequent reduction to control levels after 7 h. These effects were blocked by actinomycin D and cycloheximide. Endometrial stromal cells exhibited highly variable ODC activities at different passages. Difluoromethylornithine (DFMO) and sodium molybdate had marked antiproliferative effects in HEC-50 cultures, reducing cell numbers to 10 to 20% of control values 11 d after plating and inhibiting ODC activity by approximately 80% on Day 7. The antiproliferative effect of DFMO, but not that of molybdate, was reversed by 10 microM putrescine, the product of ODC activity. In contrast to DFMO, molybdate had no effect on ODC activity of cell homogenates. Molybdate did not elicit antizyme formation in HEC-50 cells under conditions in which putrescine did. These results indicate that ODC activity, present in both epithelial and stromal cells, as shown analytically and also by autoradiography after labeling with [3H]DFMO, may be related to cell proliferation in vivo and that proliferation of human endometrial cancer cells in culture can be arrested by DFMO and by molybdate.

KLE: a cell line with defective estrogen receptor derived from undifferentiated endometrial cancer

KLE is a cell line derived from a poorly differentiated endometrial carcinoma that is aneuploid with chromosome numbers ranging from 51 to 66 and 6-8 marker chromosomes demonstrated by G banding. Tumors harvested from five of five nude mice bearing an inoculum for more than a month resemble the original specimen, and electron microscopy shows microvilli, many junctional processes, glycogenation, and a prominent nucleolonema. The cell cytosol contains a specific binder for estradiol, but there is no estrogen receptor in the nucleus and in a study reported elsewhere (Raam et al., Breast Cancer Res. Treat. 2, 277 (1982) ) translocation to the nucleus fails to occur. The enzyme phenotype of this cell is human, non-HeLa.

Effects of estrogen and progesterone on thymidine kinase activity in the immature rat uterus

The effects of progesterone and/or 17 beta-estradiol on thymidine kinase activity and autoradiograms were investigated in immature rats. Thymidine kinase activity increased more than thirtyfold above the control level 30 hours after 17 beta-estradiol injection. The enzyme activity induced by 17 beta-estradiol was suppressed by progesterone, the dose of which was approximately 1,000-fold that of 17 beta-estradiol. The specific thymidine kinase isozyme, which was separated from 17 beta-estradiol-induced uterine thymidine kinase by diethylaminoethyl (DEAE) cellulose column chromatography and not affected by deoxycytidine triphosphate, was involved in the DNA replication and inhibited by progesterone. The autoradiogram revealed many grains due to 3H-thymidine in the endometrial epithelium, stroma, and the myometrium in the immature rat 30 hours after 17 beta-estradiol injection, whereas progesterone reduced remarkably the number of grains induced by 17 beta-estradiol in the epithelium. Progesterone seems to inhibit the increment of the specific thymidine kinase isozyme induced by 17 beta-estradiol in the endometrial epithelium.

Insensitivity to interferon of two subclones of human endometrial carcinoma cell line, HEC-1

Two cloned cell lines, HEC-IC and HEC-ID, derived from the human endometrial adenocarcinoma cell line HEC-I, were found to be as resistant to the antiviral and anticellular activities of interferon (IFN) as were the parental cells, and 2'-5' oligoadenylate (2-5A) synthetase was not induced in these clones by IFN treatment. They were sensitive to the cytotoxicity of natural killer (NK) cells but their sensitivity was not changed by treatment of the cell lines with IFN. Binding of [3H]-leucine-labelled IFN-alpha to HEC-IC cells was examined, and Scatchard plot analysis showed that HEC-IC cells did not have any high-affinity binding sites for IFN-alpha. The cells had hyperploid chromosomes. HEC-IC had three copies of chromosome 21 while HEC-ID had only one copy of chromosome 21. The results suggest that these clones may have the structural gene for the IFN receptor but that functional receptor sites may be absent.