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Biomedical subjects

Pirkko Härkönen

Publications and source records attributed to Pirkko Härkönen.

10 recordsLinked to original sources
PubMed2006

Effects of estradiol and medroxyprogesterone acetate on morphology, proliferation and apoptosis of human breast tissue in organ cultures.

BACKGROUND: Human breast tissue undergoes phases of proliferation, differentiation and regression regulated by changes of the levels of circulating sex hormones during the menstrual cycle or aging. Ovarian hormones also likely play a key role in the etiology and biology of breast cancer. Reports concerning the proliferative effects of steroid hormones on the normal epithelium of human breast have been conflicting. Some studies have shown that steroid hormones may predispose breast epithelial cells to malignant changes by stimulating their proliferation, which is known to be regulated tightly by stromal cells. The aim of this study was to investigate the effects of 17beta-estradiol and medroxyprogesterone acetate on proliferation, apoptosis, expression of differentiation markers and steroid hormone receptors in breast epithelium using an in vitro model of freshly isolated human breast tissue, in which a proper interaction of breast epithelium and stroma has been maintained. METHODS: Human breast tissues were obtained from women undergoing surgery for breast tumours. Peritumoral tissues were excised and explants were cultured for 3 weeks in medium supplemented with E2 or MPA or with E2+MPA. Endpoints included histopathological, histomorphometric and immunohistochemical assessment of the breast explants. RESULTS: Culture of breast explants for 14 or 21 days with steroid hormones increased proliferative activity and the thickness of acinar and ductal epithelium. E2-treatment led to hyperplastic epithelial morphology, MPA to hypersecretory single-layered epithelium and E2+MPA to multilayered but organised epithelium. The proliferative response to E2 in comparison to control (p < 0.001) was more pronounced than to MPA (p < 0.05) or E2+MPA (p < 0.05) at 7 and 14 days for Ki-67 and PCNA. E2 treatment also decreased the proportion of apoptotic cells after 7 (p < 0.01) and 14 (p < 0.01) days. In addition, the relative number of ERalpha, ERbeta and PR positive epithelial cells was decreased by all hormonal treatments. CONCLUSION: Organ culture system provides a model for studying the direct effects of steroid hormones and their analogues on postmenopausal human breast tissue. Addition of E2 or MPA or E2+MPA to breast explants caused characteristic changes in morphology, stimulated epithelial proliferation, lowered apoptosis ratio and decreased the relative number of epithelial cells expressing ERalpha, ERbeta and PR.

Apoptosis↗
PubMed2005

In vitro bioactivity-guided fractionation and characterization of polyphenolic inhibitory fractions from Acacia nilotica (L.) Willd. ex Del.

The present study was undertaken to evaluate antimutagenic and cytotoxic effects of different extracts/fractions of Acacia nilotica prepared by maceration method. The potency order of different extracts was more or less similar in Ames assay as well as in cytotoxic assay. Considering the maximum potential of acetone extract in both the assays, the studies were initiated to fractionate this extract. Two pure fractions, namely AN-1 and AN-2, were obtained from acetone extract, of which AN-2 was found to be of gallic acid and AN-1 fraction is still to be identified. In conclusion, the antimutagenic and cytotoxic activities exhibited by acetone extract may partially be ascribed to the presence of gallic acid and other polyphenols.

Acacia↗
PubMed2005

Cleavable ErbB4 isoform in estrogen receptor-regulated growth of breast cancer cells.

ErbB1 and ErbB2 receptors are well-characterized targets for anticancer drugs, but the clinical relevance of the related ErbB4 receptor is unknown. Here, we have assessed the clinical significance of the proteolytically cleavable ErbB4 isoforms in breast cancer patients and investigated their functions in vitro. The expression of transcripts encoding the cleavable ErbB4 isoforms associated with estrogen receptor-alpha (ER) expression (P < 0.001) and a high histologic grade of differentiation (P </= 0.002) in real-time reverse transcription-PCR analysis of 62 breast cancer samples. Despite high ErbB4 mRNA expression levels in a subset of samples, ErbB4 gene amplification was not observed. High ErbB4 protein expression levels, as assessed by immunohistochemistry, associated with a favorable outcome in ER-positive cases from a series of 458 breast cancer patients (P = 0.01), whereas no association between ErbB4 expression and survival was found among women with ER-negative cancer (P = 0.86). However, nuclear ErbB4 immunoreactivity was associated with poor survival as compared with women whose cancer had membranous ErbB4 staining (P = 0.04). In vitro, overexpression of a cleavable ErbB4 isoform in ER-positive breast cancer cells resulted in translocation of a proteolytically released intracellular ErbB4 receptor fragment into the nucleus, as well as, enhanced proliferation, anchorage-independent growth, and estrogen response element-mediated transcriptional activity. These results suggest that the association of ErbB4 expression with clinical outcome is dependent on the subcellular localization of ErbB4 and that a proteinase-cleavable ErbB4 isoform promotes growth of ER-positive breast cancer and enhances ER-mediated gene transcription.

Alternative Splicing↗
PubMed2005

Sex specific expression of progesterone receptor in mouse lower urinary tract.

Progesterone receptor (PR) was investigated immunohistochemically in the lower urinary tract of the male and female mouse. Estrogen receptor (ER)-subtype-deficient mice (ERKO, BERKO) were used to determine the possible regulation of PR expression in an ER-subtype-specific manner. PR was found to be co-expressed with ERalpha in cell nuclei of urothelium, lamina propria fibroblasts and smooth muscle cells in the female urethra. Only few PR positive cells were seen in female ERKO mice. Ovariectomy reduced and estrogen treatment restored the urethral PR expression in female wild type and BERKO mice. Thus, the expression of PR in the female urethra is estrogen-inducible via ERalpha. In male urethra, PR was co-expressed with ERbeta in the rhabdosphincter. In male, no evidence was obtained for the ER-linked control of the PR expression. No PR-positive cells were observed in the body of the bladder of either sex or any strain.

Animals↗
PubMed2005

Effects of ospemifene and raloxifene on hormonal status, lipids, genital tract, and tolerability in postmenopausal women.

OBJECTIVE: To compare ospemifene and raloxifene regarding their effects on hormones, lipids, genital tract, and tolerability in postmenopausal women. DESIGN: A randomized, double-blind study in which 118 healthy postmenopausal women received 30 (n = 29), 60 (n = 30), or 90 mg (n = 30) of ospemifene or 60 mg (n = 29) of raloxifene for 3 months. RESULTS: There were no significant differences in the baseline characteristics between study groups. In comparison with raloxifene, follicle-stimulating hormone levels decreased significantly more in the 90-mg ospemifene group and sex hormone-binding globulin levels increased more in all ospemifene groups. Total cholesterol and low-density lipoprotein cholesterol levels decreased more in raloxifene than in ospemifene groups, although the difference in low-density lipoprotein cholesterol between 90-mg ospemifene and raloxifene was not significant. Endometrial thickness did not change in any study group and endometrial biopsies showed atrophy in the majority of subjects at 3 months. All ospemifene groups demonstrated a clear estrogenic effect on the vaginal epithelium, as seen in Pap smears. This was in sharp contrast to the raloxifene group, which had no effect on the vaginal epithelium. Kupperman index decreased in all study groups during treatment. The adverse events were mild, mainly single cases, and no clustering of events was observed. There were no clinically significant abnormal findings in laboratory safety parameters. CONCLUSIONS: Ospemifene, at the dose of 90 mg/day, was more estrogenic than raloxifene, as shown by changes in serum follicle-stimulating hormone and sex hormone-binding globulin levels. Neither agent stimulated endometrium, but in contrast to raloxifene, ospemifene had a clear estrogenic effect in the vagina. Further studies with ospemifene are needed in subjects with vaginal atrophy.

Double-Blind Method↗
PubMed2005

Estrogen responsiveness of bone formation in vitro and altered bone phenotype in aged estrogen receptor-alpha-deficient male and female mice.

OBJECTIVE: Although the beneficial effects of estrogen on bone are well known, the roles of estrogen receptors (ERs) in mediating these effects are not fully understood. METHODS: To study the effects of long-term ER alpha deficiency, bone phenotype was studied in aged ER alpha knockout (ERKO) mice. In addition, ERKO osteoclasts and osteoblasts were cultured in vitro. DESIGN AND RESULTS: Histomorphometric analysis showed that the trabecular bone volume and thickness were significantly increased and the rate of bone formation enhanced in both male and female ERKO mice in comparison to the wild-type animals. In ERKO males, however, the bones were thinner and their maximal bending strengths decreased. Consistent with previous reports, the bones of knockout mice, especially of female mice, were shorter than those of wild-type mice. In addition, the growth plates were totally absent in the tibiae of aged ERKO females, whereas the growth plate cartilages were detectable in wild-type females as well as in all the males. Analysis of cultured bone marrow cells from 10- to 12-week-old mice demonstrated that 17 beta-estradiol could stimulate osteoblastic differentiation of bone marrow cells derived from ERKO mice relatively to the same extent as those derived from wild-type mice. This was demonstrated by increases in synthesis of type I collagen, activity of alkaline phosphatase and accumulation of calcium in cultures. Total protein content was, however, reduced in ERKO osteoblast cultures. CONCLUSIONS: These results show altered bone phenotype in ERKO mice and demonstrate the stimulatory effect of estrogen on osteoblasts even in the absence of full-length ER alpha.

Animals↗
PubMed2004

alpha-Trinositol inhibits FGF-stimulated growth of smooth muscle and breast cancer cells.

alpha-Trinositol (d-myo-inositol-1,2,6-trisphosphate), an isomer of the intracellular messenger IP(3), has been studied for its anti-inflammatory and other effects in animal experiments and in human. The mechanisms of action remain unknown. Several human pathologies are associated with uncontrolled production of fibroblast growth factors (FGFs). FGF-2 induces vascular smooth muscle cell proliferation, which contributes to restenosis after coronary balloon angioplasty. The expression of several FGFs is also increased in tumors. We studied the effects of the water- and lipid-soluble derivatives of alpha-trinositol on the FGF-2- and/or FGF-8-induced proliferation of human pulmonary artery smooth muscle cells (HPASMC) and S115 mouse breast cancer cells. alpha-Trinositol decreased the FGF-mediated proliferation of HPASMC and S115 cells. Membrane permeability did not seem obligatory since the lipid-soluble form of alpha-trinositol was less effective than the water-soluble derivative. These results suggest a new biological function for certain phosphoinositides in the modulation of FGF-regulated processes.

Animals↗
PubMed2004

68Ga-labeled oligonucleotides for in vivo imaging with PET.

UNLABELLED: The biologic evaluation in living rats of (68)Ga-labeled oligonucleotides as imaging agents for PET is reported. METHODS: (68)Ga, a positron-emitting radionuclide (half-life, 68 min), along with a macrocyclic chelating agent, 1,4,7,10-tetraazacyclododecane-N,N',N",N"'-tetraacetic acid (DOTA), was used for labeling of antisense oligonucleotides targeting activated human K-ras oncogene. The biologic properties of 3 different forms of the oligonucleotides-that is, 2'-deoxyphosphodiester (PO), 2'-deoxyphosphorothioate (PS), and 2'-O-methyl phosphodiester (OMe)-were studied first. The biodistribution and biokinetics were evaluated in vivo in athymic rats, each bearing a tumor of A549 cells, containing K-ras point mutation in codon 12, and a tumor of BxPC-3 cells, containing wild-type K-ras. Dynamic PET imaging lasting up to 2 h was performed immediately after intravenous injection of (68)Ga-oligonucleotide. Blank studies were performed using (68)GaCl(3) or (68)Ga-DOTA alone without oligonucleotide. The (68)Ga-antisense oligonucleotide uptake in tumors was also compared with the (18)F-FDG and (68)Ga-sense oligonucleotide uptakes. In addition, oligonucleotide binding to human plasma proteins and to human albumin was examined by means of ultrafiltration. RESULTS: The oligonucleotides can be stably labeled with (68)Ga and DOTA chelate. Intravenously injected (68)Ga-oligonucleotides of 17-mer length revealed high-quality PET images, allowing quantification of the biokinetics in major organs and in tumors. The biodistribution and biokinetics of intravenously administered (68)Ga-oligonucleotide varied considerably with the nature of the oligonucleotide backbone. CONCLUSION: We conclude that (68)Ga labeling of oligonucleotides is a convenient approach for in vivo imaging and quantification of oligonucleotide biokinetics in living animals with PET.

Animals↗
PubMed2002

Inhibition of cancer cell growth by crude extract and the phenolics of Terminalia chebula retz. fruit.

A 70% methanol extract of Terminalia chebula fruit, was studied for its effects on growth in several malignant cell lines including a human (MCF-7) and mouse (S115) breast cancer cell line, a human osteosarcoma cell line (HOS-1), a human prostate cancer cell line (PC-3) and a non-tumorigenic, immortalized human prostate cell line (PNT1A) using assays for proliferation ([(3)H]-thymidine incorporation and coulter counting), cell viability (ATP determination) and cell death (flow cytometry and Hoechst DNA staining). In all cell lines studied, the extract decreased cell viability, inhibited cell proliferation, and induced cell death in a dose dependent manner. Flow cytometry and other analyses showed that some apoptosis was induced by the extract at lower concentrations, but at higher concentrations, necrosis was the major mechanism of cell death. ATP assay guided chromatographic fractionation of the extract yielded ellagic acid, 2,4-chebulyl-beta-D-glucopyranose (a new natural product), and chebulinic acid which were tested by ATP assay on HOS-1 cell line in comparison to three known antigrowth phenolics of Terminalia, gallic acid, ethyl gallate, luteolin, and tannic acid. Chebulinic acid (IC(50) = 53.2 microM +/- 0.16) > tannic acid (IC(50) = 59.0 microg/ml +/- 0.19) > and ellagic acid (IC(50) = 78.5 microM +/- 0.24), were the most growth inhibitory phenolics of T. chebula fruit in our study.

Adenosine Triphosphate↗