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PubMed1990

Specific binding sites for insulin-like growth factor I in the ovarian stroma of women with polycystic ovarian disease and stromal hyperthecosis.

Women with polycystic ovarian disease and hyperthecosis have hyperinsulinemia and insulin resistance. It is possible that insulin in supraphysiologic concentration exerts its steroidogenic action on ovarian stromal cells through insulin-like growth factor I receptors. We undertook this study to investigate whether the ovarian stroma of women with hyperthecosis has specific binding sites for insulin or insulin-like growth factor I. Ovarian stromal tissue was obtained from seven women with normal ovulatory cycles and from five women with hyperthecosis of the ovaries. Binding studies with insulin tagged with iodine 125 and insulin-like growth factor I tagged with iodine 125 revealed specific binding sites both for insulin and insulin-like growth factor I in the ovarian stroma. The binding of insulin tagged with iodine 125 in the ovarian stroma of women with hyperthecosis (3.4% +/- 1.1% (+/- SE) per 100 micrograms protein) was significantly (p less than 0.04) lower than that observed in normal premenopausal women (8.3% +/- 1.6% per 100 micrograms protein). By contrast, the specific binding of insulin-like growth factor I tagged with iodine 125 in the ovarian stroma of women with hyperthecosis (7.1% +/- 1.7% per 100 micrograms protein) was higher than that observed in the ovarian stroma from normal women (4.5% +/- 1.7% per 100 micrograms protein), although the difference was not statistically significant. The affinity constants for these high-affinity receptors were similar (1.2 to 3.6 x 10(9) L/mol) in the two groups of women. These results indicate that (1) the ovarian stroma has specific binding sites both for insulin and for insulin-like growth factor I; (2) in women with hyperthecosis, the ovarian stroma has decreased binding sites for insulin but has normal concentrations of insulin-like growth factor I receptors; and (3) in women with hyperthecosis, stimulation of ovarian androgen synthesis by insulin may be mediated through the insulin-like growth factor I receptors.

Adult↗
PubMed1994

5 alpha-reductase inhibition by finasteride (Proscar) in epithelium and stroma of human benign prostatic hyperplasia.

Finasteride is a specific 5 alpha-reductase inhibitor that has been shown to reduce the size of human benign prostatic hyperplasia (BPH) by inhibiting the intraprostatic conversion of testosterone to 5 alpha-dihydrotestosterone. The aim of the present in vitro study was to describe in more detail the inhibitory effect of finasteride on 5 alpha-reductase in epithelium and stroma of human BPH. 5 alpha-Reductase activity in epithelium and stroma was inhibited dose-dependently by finasteride. The mean IC50 (50% inhibitory concentration) values, determined in the presence of various testosterone concentrations, were generally 2- to 4-fold lower in epithelium than in stroma. With finasteride concentrations greater than 5 nM, competitive inhibition of 5 alpha-reductase occurred both in epithelium and stroma. The mean inhibition constant Ki[nM +/- SEM] was 7 +/- 3 and 31 +/- 3 in epithelium and stroma, respectively. In the presence of finasteride concentrations < or = 5 nM, the epithelial 5 alpha-reductase seems to be inhibited in an uncompetitive manner, whereas such low finasteride concentrations cause either no inhibition (1-2 nM) or competitive inhibition (5 nM) in stroma. Our present study provides evidence that the inhibitory effect of finasteride on 5 alpha-reductase is much stronger in epithelium than in stroma. Therefore, it is conceivable that the global size-reduction of BPH under finasteride treatment is primarily due to the regression of BPH epithelium.

5-alpha Reductase Inhibitors↗
PubMed2001

In vitro modulation of steroid 5alpha-reductase activity by phospholipases in epithelium and stroma of human benign prostatic hyperplasia.

Membrane components, such as phospholipids, play an important role in the regulation of prostatic 5alpha-reductase activity. To describe in more detail the impact of such regulation on 5alpha-reductase activity, epithelial and stromal cell homogenates of human BPH were treated with phospholipases to specifically alter the structure of cellular phospholipid components. Phospholipase A(2) (PLA(2)) was used to alter the structure of the nonpolar, hydrophobic region of the membrane bilayer. Various types of phospholipase C (PLC) affect the polar, hydrophilic region of phospholipids. In epithelium and stroma, 5alpha-reductase activity was dose-dependently inhibited by PLA(2) and PLC type III. In epithelium and stroma, the mean IC(50) values of PLA(2) were 9.4 +/- 1.1 and 13.9 +/- 2.6 [U/mg protein +/- SEM], respectively. The mean IC(50) values of PLC type III in epithelium and stroma were 4.5 +/- 1.2 and 1.7 +/- 0.2 [U/mg protein +/- SEM], respectively. In epithelium as well as in stroma, 5alpha-reductase activity was more greatly inhibited by PLC type III than by PLA(2). Both in epithelium and stroma, PLA(2) significantly decreased the V(max) of 5alpha-reductase whereas its K(m) remained unaffected. A similar decrease in V(max) was found with PLC type III in epithelium and stroma. Furthermore, the K(m) of epithelial 5alpha-reductase increased significantly following the addition of PLC type III. The two phospholipases, with their specific substrate affinities and sites of hydrolysis, exhibited significantly different effects on 5alpha-reductase, indicating that 5alpha-reductase activity is not unspecifically affected by modification of the hydrophilic milieu. Rather, 5alpha-reductase activity is specifically modulated by various phospholipids and/or phospholipolysis mediated degradation products. These findings suggest that the structural composition of the lipid environment plays a fundamental role in the post-translational regulation of 5alpha-reductase activity in the epithelium and stroma of human BPH. Thus, changes in membrane phospholipid content seem to be instrumental in the expression of DHT-dependent processes.

Epithelium↗
PubMed1997

Perturbation in the ability of bone marrow stroma from patients with acute myeloid leukemia but not chronic myeloid leukemia to support normal early hematopoietic progenitor cells.

The ability of bone marrow (BM) stroma derived from patients with acute myeloid leukemia (AML) or chronic myeloid leukemia (CML) to support normal hematopoiesis was investigated using a two-stage long-term bone marrow culture (LTBMC) procedure. Of particular interest was whether leukemia-derived stroma were capable of supporting the very immature, uncommitted hematopoietic progenitor cells (HPC) which are considered to have a higher dependence and association with the BM stroma than the more mature committed HPC. Confluent stromal layers were recharged with selected populations of normal HPC enriched for the CD34+CD38- cells (immature, uncommitted HPC) or the CD34+CD38+ cells (mature, committed HPC). The weekly output of clonable granulocyte-macrophage progenitor cells (CFU-GM) was used as an indicator of the hematopoietic-supporting ability of the cultures. Stromal layers derived from 5/7 patients newly diagnosed with AML, showed significantly depressed ability to support the CD34+CD38- cells compared to stroma derived from normal donors. The supporting function of the AML-derived stroma for the more mature CD34+CD38+ cells was similar to that of the normal stroma (3/3 cases). Stromal layers derived from patients with chronic-phase CML showed normal or enhanced supporting function for the CD34+CD38- cells (5/6 cases), and likewise for the CD34+CD38+ cells (3/3 cases). This study revealed a selective defect in the ability of BM stroma from patients with AML to support the maturation of normal early uncommitted HPC, represented by the CD34+CD38- cells, whilst the ability to support the committed CD34+CD38+ cells was not affected. This suggests that the BM microenvironment may be implicated in the disease mechanism of AML. It does not, however, appear to be as clearly implicated in chronic-phase CML.

Acute Disease↗
PubMed1999

Characterization of the stage in natural killer cell development in 14.5-day mouse fetal liver using adult bone marrow stroma.

Nonstimulated fetal liver (FL) from 14.5-day gestation mice had no natural killer (NK) cell activity and <3% expressed NK1.1. Even after short-term (3-4 day) culture of FL with the late-acting cytokines, interleukin (IL)-15 or IL-2, little or no NK activity was detected. However, longer-term (13 day) culture with IL-2 plus stroma derived from bone marrow (BM) of adult mice, resulted in extensive proliferation and differentiation to mature NK cells. Cell numbers began to increase after 4 days, and by day 13, they had increased 40-fold and 69% of the cells were NK1.1+ with high NK activity and 5%-10% were NK1.1- B220+. With stroma, but no IL-2, equivalent proliferation occurred, but differentiated cells were predominantly NK1.1- B220+, not NK cells. Culture for 13 days without stroma, but with either IL-2, IL-15, FLTK3-ligand (L) or stroma-conditioned medium, resulted in less than fivefold expansion, and minimal NK activity. Culture with combinations of FLTK3-L or ckit-L plus IL-15 or IL-2 increased both cell number and NK activity, but the increase in cell number was less than that seen with stroma plus IL-2. By limiting dilution assay on stroma plus IL-2, the precursor frequency was 1/(2660+/-292) whole FL cells and the absolute number, but not the frequency, increased during culture on stroma without IL-2. The NK cell progenitors were found in sorted NK1.1- and Sca-1+ c-kit+ lineage- subpopulations at a frequency of 1/(156+/-52.5). Together, these data suggest that the NK lineage cells in FL are primarily in early stages of development. They are highly proliferative, respond to early acting cytokines and express stem cell markers.

Animals↗
PubMed1998

In vitro inhibition of androstenedione 5alpha-reduction by finasteride in epithelium and stroma of human benign prostatic hyperplasia.

Finasteride is a well known steroid 5alpha-reductase inhibitor. In this context, recently we have shown that in human benign prostatic hyperplasia (BPH) finasteride inhibits the 5alpha-reduction of testosterone to dihydrostestosterone (DHT) more effectively in the epithelium as compared to the stroma. The aim of the present study was to describe in epithelium and stroma of human BPH the effect of finasteride on the 5alpha-reduction of androstenedione, that is the second main circulating androgen in men, to androstanedione. Using a finasteride concentration of 75 nM and an androstenedione concentration of 220 nM, the mean inhibition [% +/- SEM] of 5alpha-reductase activity was significantly higher in epithelium (69 +/- 2) than in stroma (52 +/- 4). Both in epithelium and stroma, this inhibition of 5alpha-reductase activity was dose-dependent and competitive. Dixon plots as well as slope replots of Lineweaver-Burk plots showed that the mean inhibition constant Ki (nM +/- SEM) was significantly lower in epithelium (10 +/- 1 and 11 +/- 2, respectively) than in stroma (33 +/- 7 and 28 +/- 4, respectively) indicating a significantly stronger inhibitory effect of finasteride in epithelium. From those mean Ki values, it follows that in human BPH finasteride inhibits equally well both the 5alpha-reduction of androstenedione to androstanedione and testosterone to DHT. Based on these inhibition studies, there is no evidence for the coexistence of substrate-specific 5alpha-reductases converting either testosterone or androstenedione. However, the striking difference in finasteride sensitivity of the 5alpha-reduction between epithelium and stroma could be due to a cell-type specific expression of structurally different 5alpha-reductases as well as to a different access of finasteride to 5alpha-reductase in epithelium and stroma where, compared to each other, the lipid environment is significantly different.

Aged↗
PubMed1996

The role of sheep stroma in human haemopoiesis in the human/sheep chimaeras.

We have previously reported on the successful engraftment and long-term expression of human HSC (haemopoietic stem cells) in sheep following transplantation into pre-immune fetuses. The mechanism(s) underlying the support/maintenance of human haemopoiesis in sheep is not understood. In these studies we examined the ability of sheep stroma to support human haemopoiesis in vitro and compared this with support provided by human stroma. We found that, overall, human stroma was significantly more effective than sheep stroma in supporting human haemopoiesis in vitro. Nevertheless, stroma established from bone marrow of normal sheep was capable of lower-level support of the proliferation and multilineage differentiation of highly purified (CD34+, CD38-) preparations of human HSC in vitro. At lower concentrations, sheep stroma conditioned media (CM) induced human bone marrow mononuclear cells enriched for the CD34-positive fraction to enter the cell cycle at levels comparable to that of human stroma CM. However, unlike human CM, at higher concentrations, sheep CM inhibited human cells from initiating the cell cycle. These results provide a possible explanation for the long-term maintenance of low levels of human haemopoietic cell activity in human/sheep chimaeras.

Animals↗
PubMed2002

Prostate tumor-stroma interaction: molecular mechanisms and opportunities for therapeutic targeting.

Maintenance of cell and tissue homeostasis is dependent upon the dynamic balance of cell proliferation, differentiation, and apoptosis through interactions between cells and their microenvironment. The unique prostatic cellular phenotypes are induced and maintained by interaction between epithelium and adjacent stroma through intimate intercellular signaling pathways. In this article, we summarize current advances in the tumor-stroma interaction and its biologic and therapeutic implications. We specifically emphasize current studies of the possible factors driving the "vicious cycle" between stroma and emerging prostate tumor epithelial cells that may be responsible for carcinogenesis and metastasis to bone. Stroma responds both genotypically and phenotypically to tumor epithelium upon co-culture under 3-D conditions. Likewise, the emerging carcinoma responds to stromal signals that drive progression to malignancy. A vicious cycle mediated by soluble and insoluble molecules secreted by tumor cells and stroma appear be the critical factors supporting and sustaining tumor colonization in bone. Co-targeting tumor and stroma with therapeutic agents has yielded promising results both in pre-clinical models of prostate cancer and bony metastasis and in clinical trials of patients treated with a dual tumor and stroma targeting strategies. In conclusion, understanding and targeting the interaction of the tumor and its stromal microenvironmant may improve the prognosis, reduce the suffering and increase the survival of patients with advanced cancer metastasis.

Cell Communication↗
PubMed2005

Analysis of differential gene expression patterns in colon cancer and cancer stroma using microdissected tissues.

BACKGROUND AND AIMS: The surrounding cancer stroma is increasingly recognized as playing an important role in cancer proliferation, invasion, and metastasis. Here, we analyzed patterns of gene expression in colon cancer cells, surrounding stroma, and normal mucosa and normal stroma using laser capture microdissection. METHODS: Tissues were fixed from 11 patients undergoing colorectal resection for cancer, and laser capture microdissection was performed. Samples (4 per patient) were extracted for RNA, which was then used for focused gene arrays. In addition, protein expression of selected genes was determined by Western blot or immunohistochemistry. RESULTS: We showed differential expression patterns in cancer cells and surrounding stroma compared with their normal counterparts. Genes contributing to angiogenesis, cell cycle regulation, and proliferation were significantly increased in cancer cells compared with the adjacent normal mucosa. Genes contributing to angiogenesis, cancer invasion, and metastasis were significantly increased in surrounding cancer stromal cells compared with normal stroma. CONCLUSIONS: Delineating the differential patterns of gene expression between colon cancers and the surrounding reactive stroma will better determine the role of the stromal components in the progression of colon cancers and may lead to chemopreventive therapy targeted specifically to the stroma.

Adenocarcinoma↗
PubMed1993

Functional properties of isolated stroma and epithelium from rat ventral prostate during androgen deprivation and estrogen treatment.

To identify the functional activities of prostatic stroma under different hormonal conditions, isolated stroma and epithelium from rat ventral prostate (RVP, intact or one week castrated or estrogen-treated), were studied in metabolic labeling experiments. Using a semiquantitative stereological procedure, the relative proportion of the epithelial and stromal compartment was determined in situ. In addition, the distribution of the androgen receptor was visualized by in situ hybridization and by immunocytochemistry. In castrated animals protein biosynthesis of the stroma and epithelium exceeded the control value by a factor 7 and 5, respectively. In estrogen-treated animals protein biosynthesis was reduced, reaching only between one tenth and one fifth of the control value. The amount of stroma obtained from these animals was very low. These results were confirmed by stereological findings and indicate a differential regulation of prostatic stroma and epithelium after estrogen challenge and androgen deprivation. Estrogen receptor was induced in epithelium and stroma in estrogenized animals whereas the androgen receptor was reduced in experimental specimens. During estrogenization the biosynthetic activity of both stroma and epithelium is depressed, while estrogen responsivity of the epithelium in terms of estrogen receptor expression is increased. Androgen withdrawal results in active transformation of the gland through increased stromal biosynthetic activity and epithelial regression.

Androgens↗
PubMed1968

Hemopoietic colony studies. V. Effect of hemopoietic organ stroma on differentiation of pluripotent stem cells.

In heavily irradiated mice, bone marrow regeneration of either endogenous or exogenous origin was shown to occur in discrete foci comparable to the more intensively studied spleen colonies. The number of endogenous bone marrow colonies was inversely related to dose of whole body X-irradiation. Endogenous marrow colonies were found after higher doses of irradiation than were endogenous spleen colonies. Most of them were granulocytic in nature. Exogenous bone marrow colonies in lethally irradiated mice injected with bone marrow cells were proportional in number to the dose of cells injected, appeared at a time comparable to spleen colonies like which, at 7 or 8 days, they were of single differentiated cell line, either granuloid or erythroid or megakaryocytic, with a small percentage of "mixed" colonies. Whereas erythroid colonies outnumber granuloid colonies in spleen, either in situ or subcutaneously transplanted (E:G colony ratio of about 3.5), granuloid colonies outnumber erythroid in bone marrow (E:G colony ratio of about 0.7). The characteristic E:G colony ratios of spleen and marrow appear more likely to be the result of a hemopoietic organ stromal influence on pluripotent colony forming units (CFU's) than of selective lodgment of committed (unipotent) granuloid and erythroid CFU's in bone marrow and spleen, respectively, as indicated by the following. Bone marrow stem cells (CFU) which had reseeded the marrow cavity of irradiated primary recipients 18-24 hr earlier, were reharvested and retransplanted intravenously into irradiated secondary hosts. The E:G colony ratio of the colonies formed in the spleen of the secondary hosts was typical of primary spleen colonies (2.8), that of the colonies formed in the marrow cavity was typical of bone marrow colonies (0.6). Pieces of marrow stroma containing reseeded CPU's from the contralateral femur of these same primary recipients were implanted by trocar directly into the spleens of other irradiated secondary recipients. Those CPU's that developed in the intrasplenic-implanted marrow stroma yielded an. E:G colony ratio of 0.1. Those that migrated into the contiguous and remote portions of the spleen gave E:G colony ratios of 2.9 and 2.4, respectively. Irradiated marrow stroma and normal spleen CPU's (a 1 mm cube of spleen) were loaded into the same trocar and implanted directly into the spleens of irradiated mice. The spleen CFU's that migrated into the implanted marrow stroma yielded five granuloid and two mixed colonies. The larger number that developed in the host spleen yielded an E:G colony ratio of 2.9 or higher. Of those 19 mixed colonies that bridged the junction of spleen and implanted marrow stroma in each of the above two experiments, in every case, the erythroid portion of the colony was in the splenic stroma, the granuloid portion was in the marrow stroma.

Animals↗
PubMed2004

Inhibin expression in ovarian-type stroma in mucinous cystic neoplasms of the pancreas.

Mucinous cystic neoplasms (MCNs) of the pancreas are typically found in middle-aged to elderly women and contain ovarian-type stroma in the cyst wall. Whether the resemblance of this stroma to ovarian stroma is only morphologic or has more functional similarity is still unclear. Estrogen receptors (ER) and progesterone receptors (PR) have been shown to be expressed in a wide variety of tissues and tumors, including the ovarian-type stroma of MCN. Inhibin, on the other hand, has been shown to have a more restricted expression, limited to ovarian sex cord-stromal components and placental cells, and has recently been shown to be expressed in pancreatic MCNs. However, it is still unclear whether this expression is limited to MCNs of the pancreas and whether it has any diagnostic role. Seven cases of MCN (4 mucinous cystadenoma, 2 borderline MCN, and 1 mucinous cystadenocarcinoma with microinvasion), 6 cases of intraductal papillary mucinous tumor, 1 of mucinous cystic tumor of uncertain classification, 2 of mucinous noncystic adenocarcinoma, 4 of serous cystadenoma, and 4 solid pseudopapillary neoplasms were selected for this study. Five cases with normal pancreatic tissue were included as controls. Immunohistochemical stains for alpha-inhibin, ER, and PR were performed on a representative section from each case on formalin-fixed, paraffin-embedded tissue sections using a standard indirect immunoperoxidase method. All cases of MCN were in female patients with an average age of 55.3 years, showing ovarian-type stroma and clusters of alpha-inhibin-positive luteinized theca-like cells. In all these cases, moderate to strong PR positivity was also noted in the ovarian-type stroma, including many of the alpha-inhibin-positive luteinized theca-like cells. ER was expressed in 2 cases. The epithelial cells of MCNs were all negative for ER, PR, and alpha-inhibin staining. Of the other tumors, 4 solid pseudopapillary neoplasms showed positivity for only PR in the tumor cells. The remaining tumors were negative for all markers. In conclusion, the finding of alpha-inhibin positivity in MCN with ovarian-type stroma further supports its similarity to true ovarian stromal tissue and may suggest a role of complex hormonal interaction in the pathogenesis. In addition, its limited expression in MCNs of the pancreas may be diagnostically useful in difficult cases.

Adult↗
PubMed2004

The constant proportion of grana and stroma lamellae in plant chloroplasts.

The relative proportion of stroma lamellae and grana end membranes was determined from electron micrographs of 58 chloroplasts from 21 different plant species. The percentage of grana end membranes varied between 1 and 21% of the total thylakoid membrane indicating a large variation in the size of grana stacks. By contrast the stroma lamellae account for 20.3 +/- 2.5 (sd)% of the total thylakoid membrane. A plot of percentage stroma lamellae against percentage of grana end membranes fits a straight line with a slope of zero showing that the proportion of stroma lamellae is independent of the size of the grana stacks. That stroma lamellae account for about 20% of the thylakoid membrane is in agreement with fragmentation and separation analysis (Gadjieva et al. Biochim. Biophys. Acta 144: 92-100, 1999). Chloroplasts from spinach, grown under high or low light, were fragmented by sonication and separated by countercurrent distribution into two vesicle populations originating from grana and stroma lamellae plus end membranes, respectively. The separation diagrams were very similar lending independent support for the notion that the proportion of stroma lamellae is constant. The results are discussed in relation to the composition and function of the chloroplast in plants grown under different environmental conditions, and in relation to a recent quantitative model for the thylakoid (Albertsson, Trends Plant Sci. 6: 349-354, 2001).

Journal Article↗
PubMed1991

Mammary stroma modulates hormonal responsiveness of mammary epithelium in vivo in the mouse.

Several lines of evidence indicate that there may be important stromal influences on epithelial behavior in a number of adult organs. The present studies were undertaken to examine the contribution of mammary gland stroma to mammary epithelial cell hormonal responsiveness in vivo. To accomplish this, mouse mammary epithelium from a developmental state that is not responsive to estrogen (E)-regulation of progesterone receptors (3-week-old) was surgically recombined with mammary stroma from a developmental state that is E-responsive (10-week-old) and vice versa. The recombinants were then tested in vivo for the ability of E to regulate epithelial progesterone receptors. The results demonstrate that when immature nonresponsive epithelium is transplanted to mature stroma of E-responsive mice, the epithelium prematurely acquires E responsiveness. When the converse experiment was carried out, mature E-responsive epithelium retained its responsiveness when transplanted to stroma of immature nonresponsive mice. The contribution of the host systemic milieu to changes observed upon transplantation was also assessed. To do this, mature stroma was transplanted to nonresponsive mice before transplantation with nonresponsive epithelium. Under these conditions, the mature stroma was still able to promote responsiveness. Analysis of mammary gland morphology of the surgical recombinants revealed no significant differences in epithelial structures or organization that could account for the observed differences in hormone responsiveness. From these results we conclude that the local environment of mammary stroma has the capacity to influence mammary epithelial cell behavior and can modulate epithelial hormonal responsiveness in vivo. The mechanisms underlying stromal influences on epithelial behavior remain to be elucidated.

Aging↗
PubMed1986

Insulin stimulates androgen accumulation in incubations of ovarian stroma obtained from women with hyperandrogenism.

The effects of insulin and insulin-like growth factors (IGFs) on ovarian androgen production were examined in ovarian stroma obtained from four women with hyperandrogenism and three women without hyperandrogenism. In incubations of stroma obtained from all four hyperandrogenic patients, insulin alone (500 ng/ml) significantly stimulated androstenedione and testosterone release. LH alone (25 ng/ml) significantly stimulated androstenedione release in incubations of stroma obtained from three of the four hyperandrogenic patients and testosterone release in incubations of stroma obtained from one of the four hyperandrogenic patients. In stromal incubations from three of the four hyperandrogenic patients, insulin alone (500 ng/ml) resulted in a significantly greater release of androstenedione and testosterone than did LH alone (25 ng/ml). Dihydrotestosterone was released in measurable quantities in incubations of stromal tissue obtained from three of the four hyperandrogenic women. In all three instances in which dihydrotestosterone was detectable, insulin alone (500 ng/ml), but not LH alone (25 ng/ml), significantly stimulated dihydrostestosterone release. Incubations of stroma obtained from three nonhyperandrogenic, normally cycling women demonstrated low levels of androstenedione release and negligible testosterone and dihydrotestosterone release. Insulin alone (500 ng/ml) and LH alone (25 ng/ml) produced no significant increase in androstenedione release. Insulin (500 ng/ml) plus LH (25 ng/ml) significantly stimulated androstenedione accumulation in stroma obtained from two of the nonhyperandrogenic women. One insulin dose-response experiment was performed using stromal tissue obtained from a hyperandrogenic woman. In this experiment, insulin, at a dose of 50 ng/ml, was as effective as insulin at a dose of 500 ng/ml in stimulating androstenedione and testosterone release. In addition to insulin, IGF-I/somatomedin C (50 ng/ml) stimulated androstenedione and testosterone release. Relaxin (1 microgram/ml) and multiplication-stimulating activity (50 ng/ml) did not stimulate androstenedione and testosterone release. These studies suggest that human ovarian stroma may be a target tissue for insulin and IGF-I, and that hyperinsulinemia may be an important factor contributing to ovarian hyperandrogenism.

Adult↗
PubMed1993

Effect of aging on endogenous level of 5 alpha-dihydrotestosterone, testosterone, estradiol, and estrone in epithelium and stroma of normal and hyperplastic human prostate.

It is widely believed that benign prostatic hyperplasia (BPH) is associated with aging. Thus, the question arises whether or not a correlation exists between the well known prostatic androgen and estrogen accumulation and aging. To address this question, we measured 5 alpha-dihydrotestosterone (DHT), testosterone, estradiol, and estrone in epithelium and stroma of six normal (NPR) and 19 BPH and correlated the values with the age of the donors (26-87 yr). The mean DHT level in NPR epithelium was significantly higher than in NPR stroma, and also significantly higher than in epithelium and stroma of BPH. The epithelial DHT level of NPR and BPH decreased with age, the correlation being statistically significant. The stromal DHT level of NPR and BPH showed no correlation with age. Concerning testosterone, generally rather low values were found which showed no correlation with age. The mean levels of estradiol and estrone were significantly higher in BPH stroma as compared to BPH epithelium as well as to NPR epithelium and stroma. In NPR, the mean levels of estradiol and estrone were significantly higher in epithelium than stroma. In NPR and BPH, the stromal estradiol and estrone levels increased significantly with age. In epithelium such a correlation between the estrogen levels and age was not found. Our results indicate that the prostatic accumulation of DHT, estradiol, and estrone is in part intimately correlated with aging, leading with increasing age to a dramatic increase of the estrogen/androgen ratio particularly in stroma of BPH.

Adult↗
PubMed1999

Differential expression of the growth hormone receptor and growth hormone-binding protein in epithelia and stroma of the mouse mammary gland at various physiological stages.

Increasing evidence suggests that GH is important in normal mammary gland development. To investigate this further, we studied the distribution and levels of growth hormone receptor (GHR) and GH-binding protein (GHBP) in the mouse mammary gland. At three weeks of age, the epithelial component of the right fourth inguinal mammary gland of female mice was removed. These animals were then either maintained as virgins until they were killed or they were mated. One group of the mated mice was killed on day 18 of pregnancy and the remaining mated animals were allowed to carry their pups until term and were killed on day 6 of lactation. At the time of death, both the intact left and the de-epithelialized right mammary glands were collected from all three groups. Some of the intact glands served as a source of epithelial cells, free of stroma. The mRNA levels for GHR and GHBP were measured in intact glands, epithelia-cleared fat pads, and isolated mammary epithelial cells. GHR and GHBP mRNAs were expressed in both the mammary epithelium and stroma. However, the levels of both GHR and GHBP mRNAs were significantly higher in the stroma as compared with the epithelium component. This increase for both mRNAs was from 3- to 12-fold at each physiological state examined. In the intact gland, both GHR and GHBP transcripts were highest in virgins, declined during late pregnancy, and the lowest levels were found in the lactating gland. GHBP and GHR protein concentrations were also assessed in intact glands and epithelia-free fat pads. Similar to the mRNAs, GHR and GHBP protein levels (means+/-s.e.m.) in intact glands were highest in virgin mice (0.891+/-0.15 pmoles/mg protein and 0.136+/-0.26 pmoles/mg protein respectively), declined during late pregnancy (0. 354+/-0.111 pmoles/mg protein and 0.178+/-0.039 pmoles/mg protein respectively), and were lowest during lactation (0.096+0.037 pmoles/mg protein and 0.017+0.006 pmoles/mg protein respectively). Immunocytochemistry utilizing specific antisera against mouse (m) GHR and mGHBP revealed that the two proteins are localized to both the stroma and parenchyma of mouse mammary glands, with similar patterns of immunostaining throughout the different physiological stages analyzed. GHR immunolocalized to the plasma membrane and cytosol of mammary epithelial cells and adipocytes, whereas the GHBP immunostaining was nuclear and cytosolic. In conclusion, we report here that GHR and GHBP mRNAs and proteins are expressed in both the epithelium and the stroma of mammary glands of virgin, pregnant, and lactating mice. In intact glands, GHR and GHBP proteins, as well as their transcripts are higher in abundance in virgin relative to lactating mice. At all physiological stages, GHR and GHBP mRNA levels are higher in the stroma compared with the parenchyma. These findings indicate that the actions of GH in the mammary gland are both direct through its binding to the epithelia, and indirect by binding to the stroma and stimulation of IGF-I production which, in turn, affects mammary epithelial development.

Animals↗
PubMed1985

Stimulation of proliferation and differentiation of acute myeloid leukemia cells on a bone marrow stroma in culture.

Purified acute myeloid leukemia (AML) blasts were placed in Dexter cultures with and without a preestablished normal bone marrow stroma to investigate whether their proliferation was dependent on a stroma, as is the case with normal marrow cells. It was also studied whether AML cells were induced to differentiate under a stromal influence. Ten patients with untreated AML were included in the study. In most cases, AML cells were maintained at higher levels when a normal stroma was present. Cell recoveries varied widely between patients. Net cell production was apparent in nine of ten stroma cultures. In most paired cultures without a preestablished stroma, cell numbers decreased. Leukemic colony-forming cells (L-CFU) (clonogenic cells) were also recovered in higher numbers from stroma cultures, but decreased rapidly. The peak of L-CFU preceded that of AML nucleated cells. Cytogenetic analysis (three cases) confirmed the AML karyotype of cultured cells. AML blasts were tested weekly with a number of monoclonal antibodies. During culture, the percentage of cells expressing mature monocytic and granulocytic surface antigens increased markedly, suggesting progressive maturation. Morphologic maturation at the same time was incomplete. Thus, AML cells proliferate and differentiate in vitro under the influence of a normal bone marrow stroma, a property which these cells share with normal bone marrow cells.

Adult↗