Progesterone differentially regulates the membrane-type matrix metalloproteinase-1 (MT1 -MMP) compartment of proMMP-2 activation in MG-63 cells

Progesterone modulates the proliferation and differentiation of human periodontal ligament cells

Hormone deficiency has been recognized as a risk factor for periodontal disease in postmenopausal women. However, the anabolic effects of progesterone on human periodontal ligament cells (hPDLCs) are still unclear. Therefore, the objective of this study was to detect the expression of progesterone receptor (PgR) in hPDLCs and investigate the bone-sparing effects of progesterone. We detected PgR expression in hPDLCs by reverse transcriptase-polymerase chain reaction and immunocytochemistry. After progesterone stimulation, the percentage of hPDLCs entering the S + G2M phase of the cell cycle increased significantly, accompanied by an increased cell growth curve. In both basic culture medium and osteogenic medium, progesterone activated alkaline phosphatase-positive cells and alizarin red-positive nodules. Moreover, mineralization-related markers were up-regulated by progesterone in both time-dependent and dose-dependent manners. In contrast, these effects of progesterone were blocked by the PgR antagonist (RU486). Our results demonstrated that the PgR is expressed in hPDLCs at the gene and protein level, and that progesterone can stimulate the proliferation and differentiation of the hPDLCs. These findings suggest that progesterone may play a significant role in osteoblastic function of hPDLCs and may influence the maintenance of alveolar bone mass.

Effects of the components of hormone therapy on matrix metalloproteinases in breast-cancer cells: an in vitro study

A combination of E and progestogens significantly increased matrix metalloproteinase (MMP)-2 in both T47D cells (E(2)-medroxyprogesteroneacetate [MPA] and E(2)-P) and MCF-7 cells (E(2)-MPA, E(2)-P, and equilin-MPA). All combinations resulted in higher MMP-9 levels in MCF-7 cells, but higher MMP-9 levels resulted only with equilin-norethinderone in T47D cells.

Oral hormone therapy with 17??-estradiol and 17??-estradiol in combination with norethindrone acetate in the prevention of bone loss in early postmenopausal women: dose-dependent effects

OBJECTIVE

A 2-year multicenter, double-blind, randomized, placebo-controlled study examined the efficacy and safety of different doses of 17beta-estradiol (E(2)) alone and continuous-combined oral formulations of E(2) and norethindrone acetate (NETA) versus placebo in the prevention of bone loss in newly menopausal women.

DESIGN

Patients were randomized to one of seven groups: placebo, E(2) 0.25 mg, E2 0.5 mg, E(2) 1 mg, E(2) 1 mg/NETA 0.25 mg, E(2) 1 mg/NETA 0.5 mg, or E(2) 2 mg/NETA 1 mg. Treatment was a once-daily tablet taken for 26 months. The primary efficacy endpoint was the change in bone mineral density (BMD) at the lumbar spine, measured by dual-energy x-ray absorptiometry, at screening and at 13, 19, and 26 months. BMD changes at the femoral neck and trochanter were also assessed. Biochemical markers of bone metabolism were measured at baseline, and at 3, 6, 13, 19, and 26 months. Histological diagnoses of endometrial samples were tabulated for each treatment group.

RESULTS

A total of 327 women were randomized and 189 women completed the 2-year trial. BMD at the lumbar spine decreased 2.3% in the placebo group. The lowest dose of unopposed E(2) prevented bone loss at the spine and hip. Significant increases in spine BMD compared with placebo occurred in all groups of treatment with E(2) and were more pronounced in the combination groups. Compared with placebo, women receiving active treatment experienced greater reductions in bone resorption markers. The effects were evident by 6 months and generally remained stable thereafter. Adverse events, primarily associated with the endometrium, were the most common reasons for discontinuation.

CONCLUSIONS

There is a dose-dependent effect of E(2) on BMD. The addition of NETA seems to enhance the response in BMD observed with E(2). Low doses of E(2) (1 mg and lower) can be considered for the prevention of osteoporosis, while titrating the hormone dose to individual patient's needs.

Effects of 17 beta-estradiol on the expression of interstitial collagenases-8 and -13 (MMP-8 and MMP-13) and tissue inhibitor of metalloproteinase-1 (TIMP-1) in ovariectomized rat osteoblastic cells

Estrogen plays an important role in maintaining normal bone metabolism via the direct or indirect regulation of bone cells. Osteoblastic cells, as the target cells of estrogen, can secrete multiple matrix metalloproteinases (MMPs) that participate in bone remodeling. It has been demonstrated that bone loss induced by estrogen deficiency is closely related to the abnormal expression of multiple MMPs in osteoblastic cells. However, the regulating action of estrogen on the expression of interstitial collagenases MMP-8 and MMP-13 in osteoblastic cells in vivo remains unclear. We used an ovariectomized osteoporotic rat model to analyze the changes in the histomorphometric parameters of bone after and without treatment with 17beta-estradiol (E(2)); We also used immunohistochemistry and in situ hybridization to observe changes in the expression of mRNA and the proteins MMP-8, MMP-13 and TIMP-1 in osteoblastic cells in rat proximal tibia. In this study, we found that in the ovariectomized rat the expression of MMP-13 mRNA and protein increased markedly, whereas the expression of MMP-8 and TIMP-1 mRNA and protein did not change significantly. Our analysis showed that the expression of MMP-13 protein was correlated positively to bone trabecular separation, osteoid surface area, and negatively to trabecular numbers and the percentage of trabecula bone volume/total tissue volume. Our results suggest that MMP-13 plays an important role in estrogen deficiency-induced bone loss, while estrogen can inhibit bone resorption and reduce bone turnover rate by down-regulating the expression of MMP-13 in osteoblastic cells.

Effects of progesterone and 18-methyl levonorgestrel on osteoblastic cells

OBJECTIVE

To study the effects of progesterone (P) and 18-methyl levonorgestrel (LNG) on the expression of P receptors (PRA and PRB), c-fos, c-jun, and osteocalcin in the human osteosarcoma cell line MG-63 and human normal osteoblasts in order to understand the mechanism of progestin action on the proliferation and differentiation of osteoblasts.

METHODS

Cell proliferation was tested by MTT assay. The expression of PR, c-fos, c-jun, and osteocalcin was measured by semi-quantitative RT-PCR, Western immunoblot or immunocytochemistry.

RESULTS

Progesterone and LNG (10(-10)-10(-6)M) stimulated cell proliferation in a dose-dependent manner. Progesterone and LNG did not affect the expression of PRA and PRB mRNA and protein, but c-fos and c-jun mRNA and protein were upregulated in a dose-dependent manner. The expression of osteocalcin mRNA was also increased in human osteoblasts in a dose and time-dependent manner with greater effects of LNG than P, while the expression of osteocalcin mRNA in MG-63 cells was not changed by P or LNG.

CONCLUSION

Progesterone and LNG promote osteocalcin gene transcription by stimulating the expression of c-fos and c-jun, and result in osteoblast proliferation and differentiation.

Recombinant matrix metalloproteinase-14 catalytic domain induces apoptosis in human osteoblastic SaOS-2 cells

Our study previously showed that estrogen and progesterone stimulated the production of matrix metalloproteinase-14 [MMP-14, or also named membrane type matrix metalloproteinses-1 (MT1-MMP)] in osteoblastic cells. MMP-14 was implied to regulate the function of osteoblasts by degrading bone matrix or growth factors, but the mechanism is unclear. Since MMP-14 plays a role primarily through the catalytic domain, and truncated MMP-14 containing the catalytic domain and lacking transmembrane domain can be secreted into medium by cultured cells, our present study was performed to observe the direct effects of recombinant MMP-14 catalytic domain on cultured human osteoblastic osteogenic sarcoma (SaOS)-2 cells. Our data showed that recombinant MMP-14 catalytic domain activated proMMP-2 secreted into media by SaOS-2 cells, and this process was blocked by ethylenediamine tetraacetic acid (EDTA) treatment. Recombinant MMP-14 catalytic domain inhibited the adhesion of SaOS-2 cells to immobilized type I collagen or fibronectin in a dose-dependent manner, and these effects on SaOS-2 cells were abolished by EDTA. Recombinant MMP-14 catalytic domain induced SaOS-2 cells apoptosis in a dose-dependent manner, and apoptosis-inducing activity of MMP-14 catalytic domain was blocked if it was treated with EDTA. In conclusion, we revealed that recombinant MMP-14 catalytic domain induced SaOS-2 cells apoptosis. We also indirectly showed the activity of MMP-14 catalytic domain to degrade extracellular matrix (ECM) in cultures of SaOS-2 cells through Gelatin Zymograms and adhesion assay. This suggests that since adhesion of cells to ECM serves as a survival mechanism in osteoblasts, the catalytic activity of recombinant MMP-14 catalytic domain on matrix proteins contributes to its apoptosis-inducing activity.

1alpha,25-dihydroxyvitamin D3 regulates the expression of membrane-type matrix metalloproteinase-1 in normal human osteoblast-like cells

Recently, membrane-type matrix metalloproteinase-1 (MT1-MMP) was identified, and found that it can activate proMMP-2 on the cell membrane, degrade bone matrix, and participate in bone formation. Since bone is a target tissue of 1alpha,25-dihydroxyvitamin D3 [1alpha,25(OH)2D3], in the present study we observed the effects of 1alpha,25(OH)2D3 on MTI-MMP expression, and proMMP-2 activation in normal human ostcoblast-like cells (hOB). Western immunoblots showed 1alpha,25(OH)2D3 time and dose dependently stimulated MTI-MMP production. By ELISA, we found that the activation of proMMP-2 in cultures of hOB was intensified by 1alpha,25(OH)2D3. Our studies suggest that 1alpha,25(OH)2D3 induces MMP-2 activation in part by up-regulating MTI-MMP expression, and since MTI-MMP plays a role in bone metabolism, the induction of MT1-MMP levels by 1alpha,25(OH)2D3 in hOB cells may contribute to a new mechanism by which 1alpha,25(OH)2D3 promotes bone formation and stimulates bone resorption.

Effects of estriol on the proliferation and differentiation of human osteoblastic MG-63 cells

Estriol has been showed to prevent bone loss in osteoporotic rats and postmenopausal women, but the mechanisms remain unclear. In the present study, we evaluated the effect of estriol on osteoblastic MG-63 cells in vitro, and compared its action with 17beta-estradiol (E2). Cell proliferation was determined by measuring total cell numbers and [3H]thymidine incorporation. Cell function was studied by measuring alkaline phosphatase (ALP) activity and secreted osteocalcin. Our data showed that estriol stimulated MG-63 cells proliferation in a dose-dependent manner, but had no influence on ALP activity in MG-63 cells and osteocalcin production. Compared with estriol treatment, E2 showed a stronger proliferation. Estrogen receptor (ER) alpha and beta expression in MG-63 cells can be detected by Western immunoblot analysis, and the proliferative response to E2 and estriol can be all abrogated by ER antagonist ICI 182,780. In conclusion, estriol stimulates osteoblastic MG-63 cells proliferation, but has no effects on differentiation. The proliferative response to estriol is mediated by the ER. These results suggest that estriol has an effect on osteoblastic proliferation, and this may contribute to its actions on prevention of bone loss.

Expression of gelatinases and their tissue inhibitors in rat corpus luteum during pregnancy and postpartum

Extensive tissue remodeling occurs in the corpus luteum (CL) during both formation and luteolysis. Matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) are believed to play pivotal roles in these processes. In the present study, to evaluate the potential roles of matrix degrading proteases in luteal development and regression, we examined gelatinases and TIMP-1, -2, -3 mRNA expressions, as well as gelatinase activity in rat CL during pregnancy and postpartum using Northern blot, in situ hybridization, and gelatin zymography, respectively. The results showed that MMP-2 mRNA was only expressed at the early stages of pregnancy; TIMP-2 mRNA was highly expressed at the early and late pregnancy and day 1 postpartum, but could not be detected during the mid-phase of pregnancy; TIMP-3 mRNA expression was abundant during early pregnancy and peaked at day 7, but was absent from other time points examined. MMP-9 and TIMP-1 mRNAs in rat CL were below detectable level in the current study. Furthermore, the active MMP-2 was only present during the early stages of pregnancy, and no MMP-9 activity was observed in the zymogram. Taken together, our results suggest that MMP-2 and TIMP-3 may have functional roles in rat luteal formation, while TIMP-2 may be implicated in both formation and regression of the pregnant CL.

Bovine membrane-type 1 matrix metalloproteinase: molecular cloning and expression in the corpus luteum

Matrix metalloproteinase-2 (MMP-2) is produced as a zymogen, which is subsequently activated by membrane-type 1 metalloproteinase (MT1-MMP). The objectives of the present study were to clone bovine MT1-MMP and to investigate its expression in the corpus luteum. Corpora lutea were harvested from nonlactating dairy cows on Days 4, 10, and 16 of the estrous cycle (Day 0 = estrus; n = 3 for each age). The bovine MT1-MMP cDNA contained an open reading frame of 1749 base pairs, which encoded a predicted protein of 582 amino acids. Northern blotting revealed no differences (P > 0.05) in MT1-MMP mRNA levels between any ages of corpora lutea. Western blotting demonstrated that two species of MT1-MMP, the latent form ( approximately 63 kDa) and the active form ( approximately 60 kDa), were present in corpora lutea throughout the estrous cycle. Active MT1-MMP was lower (P < 0.05) in early stages of the corpus luteum than the mid and late stages, where MMP-2 activity, as revealed by gelatin zymography, was also elevated. Furthermore, immunohistochemistry revealed that MT1-MMP was localized in endothelial, large luteal, and fibroblast cells of the corpus luteum at different stages. Taken together, the differential expression and localization of MT1-MMP in the corpus luteum suggest that it may have multiple functions throughout the course of the estrous cycle, including activation of pro-MMP-2.