Association of circulating Progesterone Receptor Membrane Component-1 (PGRMC1) with breast tumor characteristics and comparison with known tumor markers

The WHO claims estrogens are 'carcinogenic': is this true?

Estrogens are in the list of carcinogenic chemicals from the World Health Organization (WHO). However, estrogens require additional factors such as stromal factors or progestogens to increase the ratio of proliferation/apoptosis for initiation of replication errors and consequent mutations to occur. These mutations require at least 5-10 years to develop into clinically detectable cancer, whereby this review is focused on breast cancer. The US National Cancer Institute highlighted a second mechanism of carcinogenicity: certain estrogen metabolites are capable of inducing DNA damage, even in low concentration. They can be assessed in the tissue and circulation. However, those deleterious reactions require excessive unrestricted oxidative cell stress, for example in industrial areas with heavy pollution. We have shown that this can be avoided using transdermal instead of oral estradiol treatment, especially important in smokers. The spectrum of metabolites is also influenced by other exogenous factors such as nutrition, physical activity and certain diseases. Reduction of breast cancer risk as demonstrated in the Women's Health Initiative (WHI) was explained by pro-apoptotic estrogen effects working after a certain 'time gap'. In addition, certain estrogen metabolites are carcinoprotective, if no genetic polymorphisms would impair their beneficial activities. Thus, since additional factors are required for both main pathways of carcinogenicity and because estrogens can even have carcinoprotective effects, we cannot agree with the statement from the WHO.

PGRMC1 promotes triple-negative breast cancer cell growth via suppressing ferroptosis

OBJECTIVE

Triple-negative breast cancer (TNBC) is the most malignant form of breast cancer with increasing incidence and mortality worldwide. The progesterone receptor membrane component-1 (PGRMC1) is a well-identified hormone receptor with unknown functions in TNBC. The current study aims to explore the involvement of PGRMC1 in regulation of glutathione metabolism and ferroptosis during development of TNBC, providing new therapy options for TNBC patients.

METHODS

Bioinformatic analysis, cell proliferation assay, western blot assay and other biochemistry methods were performed in TNBC cells.

RESULTS

Our results revealed that the expression of PGRMC1 is higher in TNBC than the other subtypes of breast cancer. Interestingly, as an iron binding protein, increased PGRMC1 expression in TNBC cells leads to resistance to ferroptosis inducer. On the contrary, silenced PGRMC1 expression enhanced sensitivity of MDA-MB231 cells to Erastin. Mechanistically, overexpression of PGRMC1 decreased the intracellular free iron concentration, which was reduced by AG205 treatment.

CONCLUSIONS

PGRMC1 increases the possibility of TNBC development through binding to intracellular iron and suppressing ferroptosis, providing the molecular basis of combined treatment for TNBC.

PGRMC1: An enigmatic heme-binding protein

Progesterone Receptor Membrane Component 1 (PGRMC1) is a heme-binding protein that has been implicated in a wide range of cell and tissue functions, including cytochromes P450 activity, heme homeostasis, cancer, female reproduction, and protein quality control. Despite an extensive body of literature, a relative lack of mechanistic insight means that how PGRMC1 functions in these different aspects of biology is largely unknown. This review provides an overview of the PGRMC1 literature, highlighting what information is rigorously supported by experimental evidence and where additional investigation is warranted. The central role of PGRMC1 in supporting cytochrome P450 activity is discussed at length. Building on existing models of PGRMC1 function, a speculative model is proposed using the reviewed literature in which PGRMC1 functions as a heme chaperone to shuttle heme from its site of synthesis in the mitochondrion to other subcellular compartments. By spotlighting knowledge gaps, this review will motivate investigators to better understand this enigmatic protein.

Primary choice of estrogen and progestogen as components for HRT: a clinical pharmacological view

Prescribing hormone replacement therapy (HRT) requires consideration of the selection of its two components, the estrogen and the progestogen. In terms of the estrogen, the decision is mainly whether to use estradiol (E2) or conjugated equine estrogens (CEE). These are the components needed to efficiently treat climacteric symptoms or/and prevent osteoporosis, currently the only labeled indications. There is still controversy regarding the adequate dosages comparing E2 and CEE; however, the consensus is that the differences in the efficacy of E2 and CEE are not a real issue. Therefore, other criteria have to be used. The first reason to add the progestogen is to avoid the development of endometrial cancer (i.e. to achieve 'endometrial safety'). Any available 'fixed-combined' HRT preparation has to be tested for sufficient endometrial efficacy, because the first question the health authorities ask before product registration relates to endometrial safety. We can generally rely on the endometrial safety of these fixed-combined products. However, it could be that we want to use 'free' combinations, which are necessary if we use transdermal E2 (patches, gel, spray), but also to individualize schedules, for example when treating bleeding problems. The question here is how to attain knowledge about the endometrial efficacy of the different progestogens and how to monitor therapy. We will try to answer these two questions from a 'clinical pharmacology' point of view, as a discipline which preferably considers pharmacological properties, but also relating to clinical practice, to achieve individualized therapy with optimal efficacy, best tolerability and minimal risks.

Ultrasound-triggered microbubble destruction enhances the radiosensitivity of glioblastoma by inhibiting PGRMC1-mediated autophagy in vitro and in vivo

BACKGROUND

Ultrasound-triggered microbubble destruction (UTMD) is a widely used noninvasive technology in both military and civilian medicine, which could enhance radiosensitivity of various tumors. However, little information is available regarding the effects of UTMD on radiotherapy for glioblastoma or the underlying mechanism. This study aimed to delineate the effect of UTMD on the radiosensitivity of glioblastoma and the potential involvement of autophagy.

METHODS

GL261, U251 cells and orthotopic glioblastoma-bearing mice were treated with ionizing radiation (IR) or IR plus UTMD. Autophagy was observed by confocal microscopy and transmission electron microscopy. Western blotting and immunofluorescence analysis were used to detect progesterone receptor membrane component 1 (PGRMC1), light chain 3 beta 2 (LC3B2) and sequestosome 1 (SQSTM1/p62) levels. Lentiviral vectors or siRNAs transfection, and fluorescent probes staining were used to explore the underlying mechanism.

RESULTS

UTMD enhanced the radiosensitivity of glioblastoma in vitro and in vivo (P < 0.01). UTMD inhibited autophagic flux by disrupting autophagosome-lysosome fusion without impairing lysosomal function or autophagosome synthesis in IR-treated glioblastoma cells. Suppression of autophagy by 3-methyladenine, bafilomycin A1 or ATG5 siRNA had no significant effect on UTMD-induced radiosensitization in glioblastoma cells (P < 0.05). Similar results were found when autophagy was induced by rapamycin or ATG5 overexpression (P > 0.05). Furthermore, UTMD inhibited PGRMC1 expression and binding with LC3B2 in IR-exposed glioblastoma cells (P < 0.01). PGRMC1 inhibitor AG-205 or PGRMC1 siRNA pretreatment enhanced UTMD-induced LC3B2 and p62 accumulation in IR-exposed glioblastoma cells, thereby promoting UTMD-mediated radiosensitization (P < 0.05). Moreover, PGRMC1 overexpression abolished UTMD-caused blockade of autophagic degradation, subsequently inhibiting UTMD-induced radiosensitization of glioblastoma cells. Finally, compared with IR plus UTMD group, PGRMC1 overexpression significantly increased tumor size [(3.8 ± 1.1) mm² vs. (8.0 ± 1.9) mm², P < 0.05] and decreased survival time [(67.2 ± 2.6) d vs. (40.0 ± 1.2) d, P = 0.0026] in glioblastoma-bearing mice.

CONCLUSION

UTMD enhanced the radiosensitivity of glioblastoma partially by disrupting PGRMC1-mediated autophagy.

E2 + norethisterone promotes the PI3K-AKT pathway via PGRMC1 to induce breast cancer cell proliferation

OBJECTIVE

This study aimed to find evidence that progesterone receptor membrane component 1 (PGRMC1) promotes estradiol (E2) + norethisterone (NET)-induced breast cancer proliferation through activation of the phosphatidylinositol-3-kinase (PI3K)-AKT pathway.

METHODS

PGRMC1-mediated breast cancer cellular proliferation and phosphorylation of PGRMC1 were studied using wild-type (hemagglutinin [HA]-tagged) MCF-7 cells, which were stably transfected with expression vector containing HA (MCF-7-HA cells), PGRMC1 (MCF-7-PGRMC1 cells) and Ser181 point mutated PGRMC1 (MCF-7-PGRMC1-S181A cells). Bioinformatics, cell proliferation, western blot, isobaric tags for relative and absolute quantitation (iTRAQ)-based RNA sequencing, real-time quantitative polymerase chain reaction (RT-qPCR) and cell cycle in vitro assays were performed to indicate the function of PGRMC1 and its possible mechanisms in breast cancer.

RESULTS

NET + E2 elicited a significant proliferation in MCF-7-Vec at 10^-6 M and 10^-10 M, respectively. MCF-7-PGRMC1 did increase the phosphorylation of AKT or ERK, which can be blocked by treatment with casein kinase 2 (CK2) inhibitor quinalizarin or in MCF-7-PGRMC1-S181A cells. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that the PI3K-AKT pathway is upregulated in MCF-7-PGRMC1 cells. Importantly, upregulation of the PI3K-AKT pathway mainly through promotion of cell cycle regulation strongly promoted cell proliferation in MCF-7-PGRMC1 cells.

CONCLUSIONS

CK2 is involved in phosphorylation of PGRMC1 at S181. The mechanism for the action of PGRMC1 for mediating proliferative progestogen effects obviously starts with promotion cell cycle regulation, and then activation of the PI3K-AKT pathway.

Solving the Puzzle: What Is the Role of Progestogens in Neovascularization?

Ovarian sex steroids can modulate new vessel formation and development, and the clarification of the underlying mechanism will provide insight into neovascularization-related physiological changes and pathological conditions. Unlike estrogen, which mainly promotes neovascularization through activating classic post-receptor signaling pathways, progesterone (P4) regulates a variety of downstream factors with angiogenic or antiangiogenic effects, exerting various influences on neovascularization. Furthermore, diverse progestins, the synthetic progesterone receptor (PR) agonists structurally related to P4, have been used in numerous studies, which could contribute to unequal actions. As a result, there have been many conflicting observations in the past, making it difficult for researchers to define the exact role of progestogens (PR agonists including naturally occurring P4 and synthetic progestins). This review summarizes available evidence for progestogen-mediated neovascularization under physiological and pathological circumstances, and attempts to elaborate their functional characteristics and regulatory patterns from a comprehensive perspective.

Molecular Characterization of Membrane Steroid Receptors in Hormone-Sensitive Cancers

Cancer is one of the most common causes of death worldwide, and its development is a result of the complex interaction of genetic factors, environmental cues, and aging. Hormone-sensitive cancers depend on the action of one or more hormones for their development and progression. Sex steroids and corticosteroids can regulate different physiological functions, including metabolism, growth, and proliferation, through their interaction with specific nuclear receptors, that can transcriptionally regulate target genes via their genomic actions. Therefore, interference with hormones’ activities, e.g., deregulation of their production and downstream pathways or the exposition to exogenous hormone-active substances such as endocrine-disrupting chemicals (EDCs), can affect the regulation of their correlated pathways and trigger the neoplastic transformation. Although nuclear receptors account for most hormone-related biologic effects and their slow genomic responses are well-studied, less-known membrane receptors are emerging for their ability to mediate steroid hormones effects through the activation of rapid non-genomic responses also involved in the development of hormone-sensitive cancers. This review aims to collect pre-clinical and clinical data on these extranuclear receptors not only to draw attention to their emerging role in cancer development and progression but also to highlight their dual role as tumor microenvironment players and potential candidate drug targets.

An Analysis of the Multifaceted Roles of Heme in the Pathogenesis of Cancer and Related Diseases

Heme is an essential prosthetic group in proteins and enzymes involved in oxygen utilization and metabolism. Heme also plays versatile and fascinating roles in regulating fundamental biological processes, ranging from aerobic respiration to drug metabolism. Increasing experimental and epidemiological data have shown that altered heme homeostasis accelerates the development and progression of common diseases, including various cancers, diabetes, vascular diseases, and Alzheimer's disease. The effects of heme on the pathogenesis of these diseases may be mediated via its action on various cellular signaling and regulatory proteins, as well as its function in cellular bioenergetics, specifically, oxidative phosphorylation (OXPHOS). Elevated heme levels in cancer cells intensify OXPHOS, leading to higher ATP generation and fueling tumorigenic functions. In contrast, lowered heme levels in neurons may reduce OXPHOS, leading to defects in bioenergetics and causing neurological deficits. Further, heme has been shown to modulate the activities of diverse cellular proteins influencing disease pathogenesis. These include BTB and CNC homology 1 (BACH1), tumor suppressor P53 protein, progesterone receptor membrane component 1 protein (PGRMC1), cystathionine-β-synthase (CBS), soluble guanylate cyclase (sGC), and nitric oxide synthases (NOS). This review provides an in-depth analysis of heme function in influencing diverse molecular and cellular processes germane to disease pathogenesis and the modes by which heme modulates the activities of cellular proteins involved in the development of cancer and other common diseases.

Suppressed estrogen supply via extra-ovarian progesterone receptor membrane component 1 in menopause

In post-menopausal women, intra-mammary estrogen, which is converted from extra-ovarian estrone (E1), promotes the growth of breast cancer. Since the aromatase inhibitor letrozole does not suppress 17β-estradiol (E2) production from E1, high intra-mammary E1 concentrations impair letrozole's therapeutic efficacy. Progesterone receptor membrane component 1 (Pgrmc1) is a non-classical progesterone receptor associated with breast cancer progression. In the present study, we introduced a Pgrmc1 heterozygous knockout (hetero KO) murine model exhibiting low Pgrmc1 expression, and observed estrogen levels and steroidogenic gene expression. Naïve Pgrmc1 hetero KO mice exhibited low estrogen (E2 and E1) levels and low progesterone receptor (PR) expression, compared to wild-type mice. In contrast, Pgrmc1 hetero KO mice that have been ovariectomized (OVX), including letrozole-treated OVX mice (OVX-letrozole), exhibited high estrogen levels and PR expression. Increased extra-ovarian estrogen production in Pgrmc1 hetero KO mice was observed with the induction of steroid sulfatase (STS). In MCF-7 cell, letrozole suppressed PR expression, but PGRMC1 knockdown increased PR and STS expression. Our presented results highlight the important role of Pgrmc1 in modulating estrogen production when ovary-derived estrogen is limited, thereby suggesting a potential therapeutic approach for letrozole resistance.

Association of circulating Progesterone Receptor Membrane Component-1 (PGRMC1) with PGRMC1 expression in breast tumour tissue and with clinical breast tumour characteristics

OBJECTIVES

Progesterone receptor membrane component-1 (PGRMC1) in breast cancer tissue has been suggested to predict a worse prognosis. The aim of this study was to assess for the first time whether PGRMC1 expressed in cancer tissue is associated with PGRMC1 blood concentrations and whether both are correlated with clinical tumour characteristics known to predict a worse outcome.

METHODS

In total, 201 patients with invasive breast cancer and 65 with benign breast disease (control group) were recruited. PGRMC1 blood concentrations were measured by a recently developed ELISA, PGRMC1 in breast cancer tissue was assessed by immunohistochemistry, and the correlation between the two was calculated. Receiver-operating characteristic (ROC) curve analysis was used to assess area under the curve (AUC). Furthermore, PGRMC1 was correlated with tumour characteristics such as tumour diameter, tumour grade and metastatic status, and with known blood tumour markers.

RESULTS

AUC for the breast cancer group was 0.713, which was significantly higher than in the control group (p < 0.01). Blood PGRMC1 concentrations had a strong (positive) correlation with tissue PGRMC1 expression (p < 0.01) but were not associated with serum tumour markers CEA, CA125, CA153 and TPS. Tissue PGRMC1, ER and cancer stage were positively associated with blood PGRMC1 (p < 0.05).

CONCLUSIONS

As PGRMC1 expression levels in cancer tissue were significantly correlated with PGRMC1 in blood, and because concentrations in blood were also positively associated with breast tumour characteristics known to predict a worse prognosis, PGRMC1 may be valuable as a new tumour marker and may be superior to known tumour markers such as CEA, CA125, CA153 and TPS.

Progesterone receptor membrane component 1 (PGRMC1) expression in canine mammary tumors: A preliminary study

Canine mammary tumors (CMT) represent the most common neoplasms in female dogs and their diagnosis and classification relies on histopathological examination. Recently, PGRMC1 has been considered to be a putative biomarker for diagnosis and prognosis in many human cancers as it is expressed in a wide variety of tumors. This study represents the first description of PGRMC1 expression in CMT. PGRMC1 expression was initially assessed by immunohistochemistry in healthy or hyperplastic tissues and in four major histopathological types of CMT: simple and complex adenomas and carcinomas. PGRMC1 staining was represented by a scoring system that considered the percentage of positive cells and staining intensity. PGRMC1 expression was defined as either weak, moderate or strong. In healthy and hyperplastic tissues almost 100% of the epithelial cells stained intensely for PGRMC1. Adenomas showed similar features but with a more variable intensity. In tubular areas of adenocarcinomas, a lower percentage of epithelial cells (30-60%) stained for PGRMC1 with a weak intensity. Both the percentage of cells and intensity of PGRMC1 staining became progressively negative in the solid parts of the tumor. Western blot analysis of healthy and neoplastic mammary tissue (carcinomas samples) revealed the presence of the 25 kDa PGRMC1 band in both types of tissue, while the 50 kDa form was mainly detected in the healthy counterpart. This study reveals that PGRMC1 is expressed in CMT and its expression pattern changes depending on the pattern of growth of CMT. Further studies are now needed to determine PGRMC1's putative role and usefulness for typing and prognosis of different CMT subtypes.

Identification of the Biomarkers and Pathological Process of Heterotopic Ossification: Weighted Gene Co-Expression Network Analysis

Heterotopic ossification (HO) is the formation of abnormal mature lamellar bone in extra-skeletal sites, including soft tissues and joints, which result in high rates of disability. The understanding of the mechanism of HO is insufficient. The aim of this study was to explore biomarkers and pathological processes in HO+ samples. The gene expression profile GSE94683 was downloaded from the Gene Expression Omnibus database. Sixteen samples from nine HO- and seven HO+ subjects were analyzed. After data preprocessing, 3,529 genes were obtained for weighted gene co-expression network analysis. Highly correlated genes were divided into 13 modules. Finally, the cyan and purple modules were selected for further study. Gene ontology functional annotation and Kyoto Encyclopedia of Genes and Genomes pathway enrichment indicated that the cyan module was enriched in a variety of components, including protein binding, membrane, nucleoplasm, cytosol, poly(A) RNA binding, biosynthesis of antibiotics, carbon metabolism, endocytosis, citrate cycle, and metabolic pathways. In addition, the purple module was enriched in cytosol, mitochondrion, protein binding, structural constituent of ribosome, rRNA processing, oxidative phosphorylation, ribosome, and non-alcoholic fatty liver disease. Finally, 10 hub genes in the cyan module [actin related protein 3 (ACTR3), ADP ribosylation factor 4 (ARF4), progesterone receptor membrane component 1 (PGRMC1), ribosomal protein S23 (RPS23), mannose-6-phosphate receptor (M6PR), WD repeat domain 12 (WDR12), synaptosome associated protein 23 (SNAP23), actin related protein 2 (ACTR2), siah E3 ubiquitin protein ligase 1 (SIAH1), and glomulin (GLMN)] and 2 hub genes in the purple module [proteasome 20S subunit alpha 3 (PSMA3) and ribosomal protein S27 like (RPS27L)] were identified. Hub genes were validated through quantitative real-time polymerase chain reaction. In summary, 12 hub genes were identified in two modules that were associated with HO. These hub genes could provide new biomarkers, therapeutic ideas, and targets in HO.