Estrogen mitogenic action. ii. negative regulation of the steroid hormone-responsive growth of cell lines derived from human and rodent target tissue tumors and conceptual implications

Carcinogenesis explained within the context of a theory of organisms

For a century, the somatic mutation theory (SMT) has been the prevalent theory to explain carcinogenesis. According to the SMT, cancer is a cellular problem, and thus, the level of organization where it should be studied is the cellular level. Additionally, the SMT proposes that cancer is a problem of the control of cell proliferation and assumes that proliferative quiescence is the default state of cells in metazoa. In 1999, a competing theory, the tissue organization field theory (TOFT), was proposed. In contraposition to the SMT, the TOFT posits that cancer is a tissue-based disease whereby carcinogens (directly) and mutations in the germ-line (indirectly) alter the normal interactions between the diverse components of an organ, such as the stroma and its adjacent epithelium. The TOFT explicitly acknowledges that the default state of all cells is proliferation with variation and motility. When taking into consideration the principle of organization, we posit that carcinogenesis can be explained as a relational problem whereby release of the constraints created by cell interactions and the physical forces generated by cellular agency lead cells within a tissue to regain their default state of proliferation with variation and motility. Within this perspective, what matters both in morphogenesis and carcinogenesis is not only molecules, but also biophysical forces generated by cells and tissues. Herein, we describe how the principles for a theory of organisms apply to the TOFT and thus to the study of carcinogenesis.

Combined 17α-hydroxylase/17,20-lyase deficiency with short stature: case study

BACKGROUNDS

17α-hydroxylase/17,20-lyase deficiency (17-OHD) is an uncommon form of congenital adrenal hyperplasia. Most patients are tall owing to delayed closure of epiphyses as a result of deficiency of sex hormones.

METHODS

We present a 17-OHD case with unusual short stature and reviewed related literature.

RESULTS

A 17-year-old female patient presented with primary amenorrhea, hypertension, hypokalemia and hypergonadotropic hypogonadism (HH). Sequencing of the CYP17A1 gene identified a homozygous c.985_987delTACinsAA in exon 6 that confirmed the diagnosis of 17-OHD. However, her height (148 cm, height standard deviation score [HSDS] -2.28) was unusually low compared with that of other 17-OHD patients. Levels of growth hormone (GH) and insulin-like growth factor (IGF)-1 were normal, and the GH provocation test excluded the possibility of GH deficiency. She underwent glucocorticoid and sex-hormone replacement therapy, reaching a final height of 152 cm (HSDS -1.59). These data suggest that tall stature is not a requisite characteristic of 17-OHD. Further studies are needed to clarify the effects of sex hormone on linear bone growth (LBG) in 17-OHD patients.

Expression and effects of JMJD2A histone demethylase in endometrial carcinoma

Previous studies have demonstrated that JMJD2A is a potential oncogene and is overexpressed in human tumors. However, its role in the endometrial carcinoma remains largely unknown. In this study, we discovered that JMJD2A was overexpressed in endometrial carcinoma, using immunohistochemistry, quantitative real- time polymerase chain reaction, and western blotting. Downregulation of JMJD2A led to reduced endometrial carcinoma RL95-2 and ISK cell proliferation, invasion and metastasis as asessed with cell counting kit-8, cell migration and invasive assays. Collectively, our results support that JMJD2A is a promoter of endometrial carcinoma cell proliferation and survival, and is a potential novel drug target.

Minireview: Putting physiology back into estrogens' mechanism of action

After decades of research, the mechanism by which estrogens stimulate the proliferation of epithelial cells in the endometrium and mammary gland, and in the carcinomas that arise in those tissues, is still not understood. Cells do not proliferate in response to 17β-estradiol (E2) alone, and although it is widely recognized that growth factors play a role in E2's proliferative effect, exactly how they are involved is unclear. It has long been known that the proliferation of endometrial epithelial cells is preceded by dramatic increases in blood flow and microvascular permeability, filling the subepithelial stroma with plasma and the proteins it contains, such as IGF-I, which is known to synergize with E2 in the induction of cell proliferation. The hyperpermeability is caused by vascular endothelial growth factor (VEGF), which is rapidly induced by E2, via the transcription factors hypoxia-inducible factor 1 and estrogen receptor α, in luminal epithelial cells in vivo. As we recently showed, VEGF is also strongly induced in endometrial cancer cells in vitro when excessive degradation of hypoxia-inducible factor 1α, caused by the abnormally high oxygen level to which cultured cells are exposed, is prevented. Putting these facts together, we now propose a new model of E2-induced proliferation in which VEGF-induced vascular hyperpermeability plays an essential role. E2 first induces the expression by endometrial epithelial cells of VEGF, which then acts in a paracrine manner to induce interendothelial cell gaps in subepithelial blood vessels, through which plasma and the proteins therein enter the adjacent stroma. Plasma carries even more E2, which circulates bound to proteins, and IGF-l, which together drive epithelial cells completely through the cell cycle.

Characterization of a plasma membrane-resident albumin-binding protein associated with the proliferation of estrogen-target, serum-sensitive cells

Estrogens control the proliferation of their target cells through a receptor-mediated pathway. Recently presented evidence suggests that estradiol cancels the proliferative inhibition exerted by human albumin (HA) and recombinant human albumin (rHA) on estrogen-target serum-sensitive cells (indirect-negative hypothesis). We postulate that this mechanism requires the presence of a plasma membrane estrogen receptor (mER) and a plasma membrane albumin-binding protein (mABP). Direct evidence confirming the presence of mERalpha in MCF7 cells has recently been presented. Herein, we now show that Western blot analysis of purified T47D membrane proteins with the C542 ERalpha specific monoclonal antibody also revealed specific, multiple M(r) mERs (67, 110, and 130k M(r)). In addition, Western blot analysis with an ABP antiserum revealed a potential 60k M(r) ABP in both MCF7 and T47D plasma membrane extracts. No such evidence was observed in similar extracts from ER-negative, serum-insensitive MDA-MB231 cells. Ligand blot analysis of similar plasma membrane extracts with bovine serum albumin confirmed the presence of a 60k M(r) ABP in MCF7 and T47D cells; again, no such evidence was observed in comparable extracts from MDA-MB231 cells. Fluorescence and confocal microscopy of MCF7 cells fixed in 2.0% paraformaldehyde/0.1% glutaraldehyde identified specific membrane ABP antigenic sites by immunocytochemistry. Serum-insensitive MDA-MB231 cells fixed and labeled similarly did not exhibit this mABP. These results suggest that the proposed mABP is expressed only in serum-sensitive estrogen-target cells and is not expressed in cells insensitive to the proliferative inhibition of HA and rHA. Also, the present data suggest that the proposed mABP may be the recognition mechanism by which both HA and rHA inhibit MCF7 and T47D cell proliferation.

Estrogen mitogenic action. III. is phenol red a "red herring"?

The reported estrogenic action of phenol red and/or its lipophilic contaminants has led to the widespread use of indicator-free culture medium to conduct endocrine studies in vitro. Because we have recently developed methods to measure large-magnitude estrogen effects in the tissue culture medium containing phenol red, we concluded that the indicator issue required further evaluation. To do this, we selected nine estrogen receptor positive (ER+) cell lines representing four target tissues and three species. We investigated phenol red using five different experimental protocols. First, 17beta-estradiol (E2) responsive growth of all nine ER+ cells lines was compared in the medium with and without the indicator. Second, using representative lines we asked if phenol red was mitogenic in the indicator-free medium. The dose-response effects of phenol red were compared directly to those of E2. Third, we asked if tamoxifen-inhibited growth equally in phenol red-containing and indicator-free medium. This study was based on a report indicating that antiestrogen effects should be seen only in phenol red-containing medium. Fourth, we asked if phenol red displaced the binding of 3H-E2 using ERK intact human breast cancer cells. Fifth, we compared E2 and phenol red as inducers of the progesterone receptor using a human breast cancer cell line. All the experiments presented in this report support the conclusion that the concentration of phenol red contaminants in a standard culture medium available today is not sufficient to cause estrogenic effects. In brief, our studies indicate that the real issue of how to demonstrate estrogenic effects in culture resides elsewhere than phenol red. We have found that the demonstration of sex steroid hormone-mitogenic effects in culture depends upon conditions that maximize the effects of a serum-borne inhibitor(s). When the effects of the inhibitor are optimized, the presence or absence of phenol red makes no everyday difference to the demonstration of estrogen mitogenic effects with several target cell types from diverse species.