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Biomedical subjects

S Saez

Publications and source records attributed to S Saez.

At least 19 recordsLinked to original sources
PubMed1992

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH, E.C. 1.2.1.12.) gene expression in two malignant human mammary epithelial cell lines: BT-20 and MCF-7. Regulation of gene expression by 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3).

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a key enzyme in the control of glycolysis. Its gene expression was analyzed in two breast cancer cell lines of human origin, BT-20 and MCF-7. We used a cDNA probe of 1.3 kb for Northern blot hybridization. It is found that GAPDH mRNA is overexpressed only in the poorly differentiated BT-20 cell line and that treatment of these cells by 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) stimulates GAPDH mRNA expression in a dose-and time-dependent manner. The present investigation on the BT-20 cells indicates that the expression of GAPDH is sensitive to 1,25-(OH)2D3 and up-regulated by low doses of this steroid.

Breast Neoplasms↗
PubMed1992

[Cancer of the breast at the time of diagnosis. A national CANAM study: analysis of 3007 cases].

Between April 1988 and February 1990, 3,007 cases of female breast cancer were recorded among people insured by CANAM*; 118 cancers were bilateral from the start and 2,889 were unilateral. At the time of diagnosis the patients' age ranged from 24 to 101 years (median: 60 years), and 35.6 percent of the tumours were virtually subclinical. Lymph node involvement was clinically absent in 75 percent of the cases and histologically absent in 57 percent. In women under 50 the proportion of small TO-T1 tumours was greater than 40 percent, which pleaded for detection before the age of 50 years. Conversely, in economically weak populations and in women who were followed up for cancerous disease, breast cancer was diagnosed at a later stage. In older (retired) women (median age: 74), who accounted for 44 percent of the whole population, the proportion of advanced tumours was practically doubled (T4: 11 percent versus 6 percent), and the probability of metastases at the time of diagnosis had risen from 4.2 to 6.1 percent. In these patients, clinical examination once a year should contribute to an earlier diagnosis.

Adult↗
PubMed1992

Measurement of occupied and non-occupied epidermal growth factor receptor sites in 216 human breast cancer biopsies.

The epidermal growth factor (EGF) is one of several growth factors involved in normal breast epithelial development and tumor proliferation. EGF and EGF-like peptide TGF alpha bind and activate the same membrane receptor protein. This receptor (EGF-R) has been recently studied in breast tumor biopsies and its detectability reported as a prognostic indicator. However, normal and tumor tissue themselves produce EGF and related peptides in variable amount. This suggests that the standard measurement of EGF-R by binding assay should reflect only the number of non-occupied receptor sites. Based on this observation, the presence of occupied sites (EGF-R2) has been assessed in 216 human mammary tumor biopsies simultaneously with the direct measurement of non occupied EGF receptor sites (EGF-R1) and the results compared to estrogen and progesterone receptor status (ER, PGR). EGF-R1 and EGF-R2 were evaluated by 2 separate (125I) EGF binding assays performed on 2 aliquots of tumor crude membrane fraction, the first one directly, the other after dissociation of the endogenously bound ligand. The validity of the method has been assessed on membrane fractions prepared from human placenta. It is shown that the dissociation does not modify the binding dissociation constant. ER and PGR were measured by the dextran coated charcoal method. Results greater than 10 fmol/mg of membrane or cytosol protein were considered as positive. It is found that EGF-R1 and EGF-R2 are detectable in 54 and 90% of the cases, indicating that EGF-R is masked by endogenous ligand in 36% of the tumors.(ABSTRACT TRUNCATED AT 250 WORDS)

Binding Sites↗
PubMed1992

[Adjuvant therapy of breast cancer with tamoxifen and endometrial carcinoma].

Twenty cases of endometrial carcinoma are reported, observed in women who had received long term tamoxifen treatment as adjuvant therapy for breast cancer. Furthermore, a specific study was carried out on an homogeneous group of 790 women with an operable breast cancer, 318 receiving tamoxifen as adjuvant treatment. Five endometrium carcinoma were observed in the group under tamoxifen versus none in the other group. From an analysis of these cases, authors will carry out a case control study to evaluate the relative risk of endometrial carcinoma for patients under tamoxifen. They underline the importance of gynecologic follow up procedures for all women receiving this endocrine therapy.

Adenocarcinoma↗
PubMed1991

1,25-Dihydroxyvitamin D3 increases epidermal growth factor receptor gene expression in BT-20 breast carcinoma cells.

In the breast cancer cell line BT-20 which displays a high number of Epidermal Growth Factor Receptors (EGF-R), we have previously observed that 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) at low concentration (0.1 nM) significantly reduces the proliferation rate while it upregulates the EGF binding capacity. The aim of the present investigation was to analyze EGF-R mRNA expression in 1,25-(OH)2D3 treated BT-20 cells. It is found that in cells treated for several days, the EGF-R mRNA levels are increased in relation to the dose from 0.01 to 1 nM. To investigate the time course of the response, cells received the drug only once and were harvested at different times. The data suggest that the stimulation of EGF-R mRNA expression is dose- and time-dependent. Therefore, the increased EGF binding capacity previously demonstrated can be related to the increase of EGF-R transcript levels.

Blotting, Northern↗
PubMed1991

Status of sex steroid hormone receptors in large bowel cancer.

To determine the potential role of sex steroid hormones in the development of colorectal tumors in humans, specific androgen (AR), estrogen (ER), and progesterone (PGR) receptors were investigated in normal mucosa (NM) and in tumor (T) paired biopsy specimens from 94 patients. Androgen receptors were detected in 98% and 96% of NM and T samples, ER in 91% and 83% of NM and T biopsy samples, whereas PGR were detected only in 14% and 10% of NM and T specimens, respectively. These incidences are independent of the sex and age of the patients. They are not related to tumor localization, histologic grade, or stages of Dukes' classification. Scatchard analysis of labeled ligand binding indicated the existence of one single class of high affinity binding sites; the calculated dissociation constant (Kd) was 1.7 +/- 0.6 10(-9) molar concentration (M) for 5 alpha-dihydrotestosterone (DHT) and 0.6 +/- 0.3 10(-9) M for estradiol (E2). These values were identical in NM and T tissue for both AR and ER. The binding capacity for DHT was 148 +/- 67 and 93 +/- 43 fmol/mg of cytosol protein in NM and T tissues, respectively (P less than 0.05). The ER content was lower and similar in NM and T biopsy specimens: 19 +/- 9 and 18 +/- 10 fmol/mg protein, respectively. The PGR content was 10 +/- 4 in NM versus 17.5 +/- 6 fmol/mg protein in T specimens. It is observed that the elevated AR in normal mucosa is not related to any known function for androgens in the digestive tract. The receptor pattern observed in tumors does not support the hypothesis previously raised in the case of chemically induced colonic tumors in rodents.

Adenocarcinoma↗
PubMed1991

Sex steroid and 1,25-dihydroxyvitamin D3 receptors in human colorectal adenocarcinoma and normal mucosa.

In order to determine the potential role of sex steroid and 1,25-dihydroxyvitamin D3 in the spreading of colorectal cancer, previously hypothesized from epidemiological and experimental data, specific androgen (AR, n = 94), estrogen (ER, n = 60), progesterone (PGR, n = 50), and 1,25-dihydroxyvitamin D3 receptors (VDR, (n = 111) were investigated in human colorectal adenocarcinoma (AC) and compared with the normal adjacent mucosa (NM). Scatchard analysis and competition studies of binding data did not reveal any difference between the biochemical behavior (affinity, specificity, and sedimentation coefficient) of the normal and tumoral tissue receptors. For ARs and ERs, high incidences were found (92 of 94 and 90 of 94 in NM versus 46 of 60 and 40 of 60 in AC, respectively) in both classes of tissues, while they were low for progesterone (7 of 50 and 5 of 50 in NM versus AC). While for sex steroid receptors the incidences did not vary with sex and age of the patients or the location and histopathological grade of the tumor, the VDR incidence was lower in AC (35 of 111) than in NM (99 of 111) and decreased significantly from the right colon to the rectum in adenocarcinoma. Binding capacities were similar in NM and AC for ERs and VDRs, whereas AR levels in NM were significantly higher than in AC. The expression of VDRs in some colorectal tumors suggests a possible clinical significance. No known function for sex steroid receptors is related to their presence in human colorectal tissues and their pattern in carcinoma does not support any hypothesis previously raised in the case of chemically induced colonic tumors in rodents.

Adenocarcinoma↗
PubMed1991

1,25-Dihydroxyvitamin D3 receptors and human colon adenocarcinoma.

Epidemiological evidence suggests that dietary calcium and 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) might have a protective effect against colorectal cancers. Since the presence of receptors is required for steroid action, specific 1,25-(OH)2D3 receptors (RD3) were investigated in biopsies taken at different levels of the colon. The study involved 90 biopsies from patients operated on for colorectal adenocarcinoma. They were paired biopsies from adenocarcinoma tissue and adjacent normal mucosa. In addition, 26 normal intestinal mucosa biopsies from patients without cancer were examined. RD3 receptors were assayed in tissue extract by the dextran-coated charcoal technique and also characterized by sucrose density gradient sedimentation. Scatchard analysis showed a single class of specific high affinity-low capacity sites binding for 1,25-(OH)2D3. The incidence of RD3 was 86 per cent in normal mucosa (n = 77) and lower in carcinoma (n = 34), for which the incidence decreased significantly (P less than 0.001) from right colon (58 per cent) to left colon (37 per cent) and rectum (19 per cent). These data suggest that the normal colon is a potential target organ for 1,25-(OH)2D3 which might modulate calcium transport in the colon. Loss of receptivity to 1,25-(OH)2D3 is associated with malignant transformation.

Adenocarcinoma↗
PubMed1991

Effects of an androgenic derivative on pre-established mammary tumours chemically induced in the rat.

The effects were studied of an androgenic derivative--danazol--administered at doses of 10-12 mg kg-1 day-1 during 97 days to rats with dimethylbenz[a] anthracene-induced mammary tumours. Our main observations were as follows. (a) Danazol did not influence ovarian function at the end of the assay. (b) The treatment with danazol reduced the incidence (P less than 0.05), number of tumours (P less than 0.05) and volume of malignant mammary tumours; on the other hand, the values of these parameters for benign tumours and those of doubtful expression were similar in both experimental groups. (c) Such differential action of Danazol seems to be due to the different incidence and/or content of receptors of both types of tumours. (d) The latter results lead to a hypothesis for the mechanism of action of danazol based on its behaviour at different levels.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1990

Influence of experimental conditions on osteoblast activity in human primary bone cell cultures.

Primary bone cell cultures were derived from human bone explants. Cellular activity was characterized by the alkaline phosphatase (AP) activity, osteocalcin, and type I and III collagen secretions in the supernatant. The determination of bone cell activity was performed in three different wells. No significant difference was noted between wells: the coefficient of variation was 8.0 +/- 2.9% for AP activity, 18.3 +/- 1.9% for osteocalcin secretion, and 22.5 +/- 14.3% for collagen. The AP activity and osteocalcin secretion significantly decreased with the number of passages: they were the highest after the first passage. Between each subject, the coefficient of variation was 85% for AP activity and osteocalcin secretion and 63 and 57% for type I and III collagen secretion, respectively. The AP activity did not differ with the age or sex of the donor. In contrast, osteocalcin secretion was significantly lower in females than in males. In males, osteocalcin significantly decreased with the age of the donor (r = -0.61; p less than 0.05). Cellular activity did not depend on the site of the biopsy. When bone explants from one donor were cultured in two different petri dishes, the activity of cells was similar in both dishes, except in one case. Primary cell cultures derived from human bone explants are the only model providing untransformed osteoblastlike cells of human origin. Because of the experimental conditions, some factors may have influenced the cellular activity and they must be taken into account to validate further in vitro studies.

Adolescent↗
PubMed1990

Evidence of 1,25-dihydroxyvitamin D3-receptors in human digestive mucosa and carcinoma tissue biopsies taken at different levels of the digestive tract, in 152 patients.

Epidemiological and experimental data suggest that dietary calcium and 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) are protective against colorectal cancers, while their activity on colon mucosa still remains unknown. Since the presence of receptors is required for steroid action, specific 1,25-(OH)2D3 receptors were investigated in biopsies taken at different levels of the digestive tract from the oesophagus to the rectum and in pancreas. The total study involved biopsies from 152 patients. In 82% of the cases they were paired biopsies in adenocarcinoma tissue and in adjacent normal mucosa (NM). There were 120 operated on for colorectal adenocarcinoma (HCRA). 1,25-(OH)2D3 receptor was assayed in tissue extract by the dextran-coated charcoal (DCC) technique and also characterised by sucrose density gradient centrifugation. Scatchard analyses showed a single class of specific high affinity-low capacity sites binding for 1,25-(OH)2D3 with a Kd = 1.48 +/- 0.8 x 10(-10) M (n = 119). The sedimentation coefficient of the steroid receptor complex was approximately 3.2 S. The incidence of 1,25-(OH)2D3 receptors was significantly higher in NM (82.5%) than in HCRA (34.5%). In HCRA this incidence decreased from right colon (64.7%) to left colon (27.7%) and rectum (15%). All positive HCRA in left colon and rectum (16/76) were histologically well differentiated. The receptor content in NM and HCRA was in the same range: (median) 10-314 (58) and 13-175 (64) fmol/mg protein. These data suggest that 1,25-(OH)2D3 may modulate calcium transport in colon, as in the intestine. Also, loss of receptivity to 1,25-(OH)2D3 is observed as associated with malignant transformation of the human colorectal mucosa.

Biopsy↗
PubMed1990

Insulin like growth factor I hormonal regulation by growth hormone and by 1,25(OH)2D3 and activity on human osteoblast-like cells in short-term cultures.

IGF-1 has been shown to be locally produced in several tissues and to play a role in the regulation of cellular activity. We have investigated its production in short-term cultures of human bone derived cells, and the regulation of this production by growth hormone (GH) and by 1,25 dihydroxyvitamin D3 (1,25(OH)2D3). Bone cells obtained from surgical bone biopsies produced and secreted IGF-1 in their culture media. In four days cultures of bone-derived cells recombinant human r-IGF-1 at 20 ng/mL increased the alkaline phosphatase activity and the osteocalcin (bone gla protein) secretion, two specific markers of bone formation. This stimulation occurred only in the presence of 1,25(OH)2D3. Human bone cells exposed to GH increased their alkaline phosphatase activity, but no osteocalcin was detectable. However, in the presence of 1,25(OH)2D3 (1 nM), GH in concentrations of 8 to 40 nM increased by 30-50% the alkaline phosphatase activity and by 50 to 100% the osteocalcin secretion of human bone cells. At the same concentrations, GH also increased by 140% endogenous IGF-1 levels in cell culture supernatants, 1,25(OH)2D3 (10 nM) also increased time- and dose-dependently, IGF-1 levels in human bone cell supernatants, and stimulated dose-dependently alkaline phosphatase activity and osteocalcin secretion. It is therefore suggested that by regulating local production of growth factors such as IGF-1, GH and 1,25(OH)2D3 may modulate the metabolism of human bone cells.

Adult↗
PubMed1990

[Comparative study of the content of 1,25-dihydroxyvitamin D3 receptors in digestive mucosa and adenocarcinoma].

We have studied and compared the 1,25-dihydroxyvitamin D3 receptor (RD3) content of 154 human digestive carcinoma with the normal mucosa one, removed at distance from the same surgical specimen. The distribution of biopsies is as follows: 5 oesophagus, 10 stomach, 6 small bowel, 35 right colon, 47 left colon, 40 rectum and 11 pancreas. RD3 were measured by the Dextran Coated Charcoal method and characterized by sucrose gradient ultracentrifugation. One single class of high affinity binding sites (kD = 1.5 +/- 0.7 x 10(-10) M) was defined, with a sedimentation coefficient of approximately 3.4 S. The RD3 was present in the 6 samples of small bowel and in 82% of whole normal mucosa, whatever their localization along the digestive tract and pancreas, while in the tumoral tissue, the RD3 was positive in only 32% of the cases. In these tumor specimens the incidence decreases from 64% in the right colon to 27% in the left colon and only 15% in the rectum (P less than 0.001). RD3 rates vary slightly with the localization and are of the same level in normal tissues and in tumors: 10-314 (median = 59) vs 13-175 (median = 64) (P greater than 0.005) respectively. No significative variations relating to age or sex of patients were found. However, all RD3 positive tumors from left colon and rectum were well differentiated histologically. These results show that the normal colonic mucosa is a potential target for 1,25-dihydroxyvitamin D3, which can play a role in the metabolism of calcium and other ions. They also suggest that vitamin D3 could be a modulator of colorectal cell growth and differentiation and its receptor is frequently lost during malignant transformation.

Adenocarcinoma↗
PubMed1990

[Antihormonal treatments in breast cancer in the woman. Role of estrogen antagonists].

Hormone treatment of breast cancer has been common practice for many years. More recently, findings on the hormonal mechanism of action on the target cells have provided a better approach of hormone-dependency and prognosis. Moreover, new hormonal synthetic molecules are now available. They are effective on specific activities of the endocrine system in well defined conditions. Administration of these drugs requires caution and previous evaluation of the patients' hormonal status conjugated to biological data of the tumor itself in view of obtaining efficient control of tumor growth.

Breast Neoplasms↗
PubMed1989

The effect of 1.25 dihydroxyvitamin D3 on binding and internalization of epidermal growth factor in cultures cells. Studies on BT-20 cells using quantitative electron microscope autoradiography.

The biological effects of 1.25 (OH)2D3 on epidermal growth receptor (EGF-R) and on EGF internalization were examined in human mammary carcinoma BT-20 cells. In this cell line, with known amplification of the epidermal growth factor receptor gene. EGF was not stimulatory for growth. Biological assay and quantitative EM autoradiography combined with iodinated ligand binding to specific receptors demonstrated that the number of binding sites unit of length of plasma membrane was 2.48-fold higher in treated than in control cells. I-EGF was progressively internalized in a time-and temperature-dependent manner after selective association with the membrane-coated pits. No modification of the time course of I-EGF internalization was noted in the control and in the treated cells, but a different distribution of the labeling in the subcellular compartment was observed in treated cells. In 1.25(OH)2D3-treated batches, the grain density remained low in the receptosomes throughout the experiment, whereas it was high and occurred early in the lysosomes. On the other hand, in control cells, the grain density of the receptosomes was high, whereas it occurred late and was relatively low in the lysosomes. These data suggest that 1.25(OH)2D3 is a regulator of EGF-R level in BT-20 cell line, but it cannot affirmed whether this effect is direct or mediated by other parameters.

Autoradiography↗
PubMed1989

Increased epidermal growth factor receptor level in breast cancer cells treated by 1,25-dihydroxyvitamin D3.

The effects of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) on epidermal growth factor receptor (EGF-R) level regulation was investigated on a human breast cancer cell line (BT-20). These cells display a great number of EGF-R (1 +/- 0.4 x 10(6) sites per cell). Scatchard analysis of binding data indicates the presence of two classes of sites: one of high affinity (Kd = 0.48 +/- 0.2 nM), the other of low affinity and higher capacity (Kd = 2.24 +/- 0.93 nM). Treatment of cells by 1,25(OH)2D3 for several days induces a progressive increase of the EGF-R number of sites per cell. This effect is dose and time dependent and results in a 3-fold enhancement of EGF-R binding in cells treated for 15 days, which involves the two classes of binding sites in the same proportion. This effect is not due to modifications of the EGF internalization and degradation processes. Inhibition of the effect of 1,25(OH)2D3 by cycloheximide suggests that it is dependent on new protein synthesis. There are no data in favor of a reduced occupancy of EGF-R sites by EGF-like substance accounting for the increase of unoccupied sites. Analysis of 125I binding by quantitative transmission electron microscope autoradiography illustrates the observation of a higher number of sites on the plasma membrane in treated than in control cells.

Autoradiography↗
PubMed1989

In vitro study of effects of 1,25 dihydroxyvitamin D3 on the morphology of human breast cancer cell line BT.20.

The morphological effect induced by 1,25 dihydroxycholecalciferol - 1,25(OH)2VitD3 - on the malignant human breast cell line BT.20 was studied. This cell line is devoid of oestrogen (ER) and progesterone (PGR) receptors. This effect, which requires treatment for at least 3 days, was evidenced by an increase in the cell projection surface, assessed on scanning electron microscopy (SEM) and by quantimetric analysis, for optimal final concentrations of 1.25(OH)2VitD3 in the medium of the order of 10(-11)M. The cells became more spread out and rounded with many junctional systems; there was occlusion of the intercellular space, but hardly any cells overlapped. The cytoskeleton was considerably developed, with microtubules running parallel to the cell surfaces associated with microfilaments. This positive action on cell differentiation was very similar to that noted regarding the reduction in growth under 1,25(OH)2VitD3 treatment. The two actions were, however, observed at different times and with different concentrations of 1,25(OH)2VitD3 in the medium.

Breast Neoplasms↗