Progesterone Receptor Membrane Component 1 Levels Research Articles

New Insights as to Why Progesterone Receptor Modulators, such as Mifepristone, Seem to Be More Effective in Treating Cancers that Are Devoid of the Classical Nuclear Progesterone Receptor.

Mifepristone treatment for advanced cancer has demonstrated considerable improvement in both length and quality of life in patients who no longer have any other treatment options. The target is the progesterone induced blocking factor (PIBF), which helps the tumor to invade the normal tissue and proliferate and suppress cellular immunity. Most of the benefit has been observed in cancers not associated with the classical nuclear progesterone receptor (nPR). There are data showing that the presence of a nPR may be associated with a better prognosis. Membrane PRs seem to be responsible for PIBF secretion. Mifepristone, possibly fails to block another P associated protein that enables the tumor to proliferate, e.g., the progesterone receptor membrane component-1 (PGRMC-1) protein. One hypothesis is that the nPR helps to inhibit tumor production of PGRMC-1 protein. Thus, mifepristone may inhibit tumor spread by suppressing PIBF, but this may be negated by blocking the nPR, allowing PGRMC-1 levels to increase.

Progesterone receptor membrane component 1 promotes the growth of breast cancers by altering the phosphoproteome and augmenting EGFR/PI3K/AKT signalling.

BackgroundIncreased expression of the progesterone receptor membrane component 1 (PGRMC1) has been linked to multiple cancers, including breast cancer. Despite being a regulatory receptor and a potential therapeutic target, the oncogenic potential of PGRMC1 has not been studied.MethodsThe impact of PGRMC1 on breast cancer growth and progression was studied following chemical inhibition and alteration of PGRMC1 expression, and evaluated by using online-based gene expression datasets of human breast cancer tissue. MTS, flow cytometry, qPCR, Western blotting, confocal microscopy and phosphoproteome analysis were performed.ResultsWe observed higher PGRMC1 levels in both ER-positive ZR-75-1 and TNBC MDA-MB-468 cells. Both chemical inhibition and silencing decreased cell proliferation, induced cell-cycle arrest, promoted apoptosis and reduced the migratory and invasive capabilities of ZR-75-1 and MDA-MB-468 cells. Further, phosphoproteome analysis demonstrated an overall decrease in activation of proteins involved in PI3K/AKT/mTOR and EGFR signalling pathways. In contrast, overexpression of PGRMC1 in non-malignant MCF10A cells resulted in increased cell proliferation, and enhanced activity of PI3K/AKT/mTOR and EGFR signalling pathways.ConclusionsOur data demonstrate that PGRMC1 plays a prominent role in regulating the growth of cancer cells by altering the PI3K/AKT/mTOR and EGFR signalling mechanisms in both ER-positive and TNBC cells.

Expression of genes that regulate follicle development and maturation during ovarian stimulation in poor responders

Research questionSex hormone-binding globulin (SHBG), androgen receptor (AR), LH beta polypeptide (LHB), progesterone receptor membrane component 1 (PGRMC1) and progesterone receptor membrane component 2 (PGRMC2) regulate follicle development and maturation. Their mRNA expression was assessed in peripheral blood mononuclear cells (PBMC) of normal and poor responders, during ovarian stimulation. DesignFifty-two normal responders and 15 poor responders according to the Bologna criteria were enrolled for IVF and intracytoplasmic sperm injection and stimulated with 200 IU of follitrophin alpha and gonadotrophin-releasing hormone antagonist. HCG was administered for final oocyte maturation. On days 1, 6 and 10 of stimulation, blood samples were obtained, serum hormone levels were measured, RNA was extracted from PBMC and real-time polymerase chain reaction was carried out to identify the mRNA levels. Relative mRNA expression of each gene was calculated by the comparative 2−DDCt method. ResultsDifferences between mRNA levels of each gene on the same time point between the two groups were not significant. PGRMC1 and PGRMC2 mRNA levels were downregulated, adjusted for ovarian response and age. Positive correlations between PGRMC1 and AR (standardized beta = 0.890, P < 0.001) from day 1 to 6 and PGRMC1 and LHB (standardized beta = 0.806, P < 0.001) from day 1 to 10 were found in poor responders. PGRMC1 and PGRMC2 were positively correlated on days 6 and 10 in normal responders. ConclusionsPGRMC1 and PGRMC2 mRNA are significantly decreased during ovarian stimulation, with some potential differences between normal and poor responders.

Abstract 3481: Sigma-2 ligands sensitize triple negative breast cancer cells to PARP inhibitor treatment

Abstract Triple-negative breast cancer (TNBC) accounts for 15-25% of breast cancer cases. Effective targeted treatment for TNBC is lacking. Poly (ADP-ribose) polymerase (PARP) is a key enzyme involved in single-strand DNA break repair. PARP inhibitors have been used in combination with various chemotherapeutic agents in TNBC with limited success. The sigma-2 receptor is associated with cellular proliferation and quiescence and has been used as the target for imaging solid tumors by positron emission tomography. The sigma-2 receptor has been identified as progesterone receptor membrane component 1 (PGRMC1) protein complex. Recent work has suggested that the sigma-2 receptor may also be an effective therapeutic target. In this study we looked for potential synergy between PARP inhibitors and sigma-2 ligands using a triple negative breast cancer cell line, MDA-MB231. We showed that the sigma-2 ligand, SW43, and a PGRMC1 ligand, AG205, induced cell toxicity and caspase 3 activation in a dose-dependent manner. The combination of SW43 and PARP inhibitor, Olaparib, resulted in additive cytotoxicity by cell viability assay and colony forming assay. Olaparib inhibited PARP activity in MDA-MB231 cell line, suggesting that the single-strand DNA break repair may be inhibited. SW43 and AG205 treatment decreased PGRMC1 and EGFR protein levels, suggesting that sigma-2/PGRMC1 ligands reduce growth factor signaling. In conclusion, SW43 and Olaparib induce cell death by separate signaling pathways. Sigma-2 ligands may selectively sensitize tumors to PARP inhibitor treatment in triple negative breast cancer patients. Citation Format: Chenbo Zeng, Julia Mankoff, Robert H. Mach. Sigma-2 ligands sensitize triple negative breast cancer cells to PARP inhibitor treatment. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3481. doi:10.1158/1538-7445.AM2015-3481

PGRMC1 Elevation in Multiple Cancers and Essential Role in Stem Cell Survival.

Cancer is one of the leading causes of death in America, and there is an urgent need for new therapeutic approaches. The progesterone receptor membrane component 1 (PGRMC1) is a cytoch-rome b5 related protein that binds heme and is associated with signaling, apoptotic suppression and autophagy. PGRMC1 is essential for tumor formation, invasion and metastasis, and is upregulated in breast, colon, lung and thyroid tumors. In the present study, we have analyzed PGRMC1 levels in over 600 tumor sections, including a larger cohort of lung tumors than in previous studies, and report the first clinical analysis of PGRMC1 levels in human oral cavity and ovarian tumors compared to corresponding nonmalignant tissues. PGRMC1 was highly expressed in lung and ovarian cancers and correlated with patient survival. PGRMC1 has been previously associated with drug resistance, a characteristic of cancer stem cells. The stem cell theory proposes that a subset of cancerous stem cells contribute to drug resistance and tumor maintenance, and PGRMC1 was detected in lung-tumor derived stem cells. Drug treatment with a PGRMC1 inhibitor, AG-205, triggered stem cell death whereas treatment with erlotinib and the ERK inhibitor, PD98059, did not, suggesting a specific role for PGRMC1 in cancer stem cell viability. Together, our data demonstrate PGRMC1 as a potential tumor biomarker across a variety of tumors, as well as a therapeutic target for cancer stem cells.

Progesterone Regulation of Progesterone Receptor Membrane Component 1 (PGRMC1) Sumoylation and Transcriptional Activity in Spontaneously Immortalized Granulosa Cells

Progesterone (P4) receptor membrane component (PGRMC)1 is detected as a 22-kDa band as well as higher molecular mass bands (>50 kDa) in spontaneously immortalized granulosa cells. That these higher molecular mass bands represent PGRMC1 is supported by the findings that they are not detected when either the primary antibody is omitted or the PGRMC1 antibody is preabsorbed with recombinant PGRMC1. Some but not most of the higher molecular mass bands are due to oligomerization. At least one of the higher molecular mass bands is sumoylated, because PGRMC1 coimmunoprecipitates with small ubiquitin-like modifier protein-1. Moreover, in situ proximity ligation assays reveal a direct interaction between PGRMC1 and small ubiquitin-like modifier protein-1. This interaction is increased by P4. Finally, the higher molecular mass forms of PGRMC1 localize to the nucleus. An analysis of transcription factor activity demonstrates that P4 suppresses T-cell factor/lymphoid enhancer factor (Tcf/Lef) activity through a PGRMC1-dependent mechanism, because treatment with PGRMC1 small interfering RNA depletes PGRMC1 levels and attenuates P4's effects on Tcf/Lef activity. In addition, transfection of a PGRMC1-Flag fusion protein enhances basal Tcf/Lef activity, which is suppressed by P4 treatment. Conversely, transfection of a PGRMC1-Flag protein in which all the sumoylation sites are mutated increases basal Tcf/Lef activity but attenuates P4's ability to suppress Tcf/Lef activity. Therefore, the ability to suppress Tcf/Lef activity is likely an essential part of the mechanism through which P4 activation of PGRMC1 regulates the gene cascades that control granulosa cell function with this action being dependent in part on the sumoylation status of PGRMC1.

Progesterone Receptor Membrane Component 1 Modulates Human Cytochrome P450 Activities in an Isoform-Dependent Manner

Cytochromes P450 (P450s) catalyze the metabolism of a wide spectrum of compounds. Recently, progesterone receptor membrane component 1 (PGRMC1), which shares a key structural motif with cytochrome b(5), has been reported to bind to sterol- or steroid-synthesizing P450s, enhancing their activities. In this study, we investigated whether PGRMC1 affects human drug-metabolizing P450 activities. Using coexpression systems for PGRMC1 and P450s (CYP3A4, CYP2C9, or CYP2E1) in HepG2 cells, we found that PGRMC1 decreased the V(max) values and increased the K(m) values of the CYP3A4 activities, and it decreased the V(max) values but did not affect the K(m) values of the CYP2C9 activities. In contrast, PGRMC1 hardly affected the CYP2E1 activities. These results suggest that PGRMC1 negatively modulates the drug-metabolizing activities of P450, although it was isoform but not substrate dependent. It is worth noting that coimmunoprecipitation analysis using coexpression systems for FLAG-PGRMC1 and Myc-P450s in human embryonic kidney 293 cells revealed that PGRMC1 interacts with all three P450s, although the affinity seemed to vary. In 29 human liver microsomes (HLMs), there was a 5-fold variability in the PGRMC1 protein levels. By the correlation analyses using the P450 activities and the PGRMC1 levels, we could neither observe the contribution of PGRMC1 to the P450 activities in HLMs nor that of the NADPH-cytochrome P450 reductase or cytochrome b(5). In conclusion, in contrast to sterol- or steroid-synthesizing P450s, we found that PGRMC1 negatively modulates the human drug-metabolizing activities of P450 through direct interaction. Further studies are needed to determine the clinical significance of PGRMC1 in the pharmacokinetics of drugs.

Changes in PGRMC1, a potential progesterone receptor, in human myometrium during pregnancy and labour at term and preterm

This study assesses the role of progesterone receptor membrane component 1 (PGRMC1) in actions of progesterone (P4) on human myometrium during pregnancy and labour. Myometrial tissues were obtained from non-pregnant patients during hysterectomy or pregnant women undergoing C-section at term and preterm, before and during labour. PGRMC1 expression in myometrial tissues and in a human myometrial cell line (HM9) was assessed by western blots and RT-PCR. The subcellular localization of PGRMC1 in HM9 was performed by immunofluorescence staining. Isometric contractions of myometrial tissues were obtained in response to P4 with and without addition of specific antibodies against PGRMC1. Endogenous and over-expressed PGRMC1 proteins are detected by western blots in myometrial tissues, HM9 and 293 cells, respectively. PGRMC1 is localized to the plasma membrane, cytoplasm and nuclear membranes. PGRMC1 is lower in myometrium of women at term either not in labour (P = 0.004) or in labour (P = 0.005) compared with tissues from women in preterm non-labour. PGRMC1 levels are also decreased (P = 0.02) in myometrial tissues from women during preterm labour compared with preterm non-labour. P4 rapidly inhibits contractions of myometrial tissues compared with control (P < 0.05) in vitro. Pretreatment of myometrial strips with PGRMC1 antibody, suppresses the P4-induced relaxation (P < 0.05). PGRMC1 may mediate the non-genomic action of P4 and the relaxation effect on human myometrium during pregnancy. A decrease in PGRMC1 during term or preterm labour might contribute to the 'functional withdrawal' of P4 action and shift the balance to a state of heightened uterine contractility.

Down-regulation of progesterone receptor membrane component 1 (PGRMC1) in peripheral nucleated blood cells associated with premature ovarian failure (POF) and polycystic ovary syndrome (PCOS)

BackgroundProgesterone receptor membrane component 1 (PGRMC1) is a member of a progesterone-binding complex implicated in female reproduction. We aimed i) to determine the natural expression of PGRMC1 in peripheral nucleated blood cells throughout the menstrual cycle and ii) to investigate any association between PGRMC1 levels in leukocytes and conditions characterized by reduced fertility.MethodsWe analyzed PGRMC1 expression in peripheral leukocytes from 15 healthy cycling women over four weeks. Additionally, we determined PGRMC1 levels in samples from patients with premature ovarian failure (POF) and polycystic ovary syndrome (PCOS) as well as in healthy postmenopausal women and male controls. The levels of PGRMC1 protein in nucleated peripheral blood cells were quantified by Western blot analysis.ResultsPGRMC1 levels did not vary significantly throughout the menstrual cycle. We observed a significant down-regulation of PGRMC1 in postmenopausal women and in patients with premature ovarian failure (POF) and polycystic ovary syndrome (PCOS) when compared to early follicular phase of healthy women.ConclusionThis study suggests that reduced levels of PGRMC1 in peripheral leukocytes are associated with perturbed ovulatory function.