Estrogen suppresses breast cancer proliferation through GPER / p38 MAPK axis during hypoxia

Utility of G protein-coupled oestrogen receptor 1 as a biomarker for pan-cancer diagnosis, prognosis and immune infiltration: a comprehensive bioinformatics analysis

BACKGROUND

The G protein-coupled oestrogen receptor (GPER) 1 mediates non-genomic oestrogen-related signalling and plays an important role in the regulation of cell growth and programmed cell death through multiple downstream pathways. Despite the increasing interest in the role of GPER1 in cancer development, no pan-cancer analysis has been available for GPER1.

METHODS

In this study we performed a comprehensive analysis of the role of GPER1 in pan-cancer via Human Protein Atlas (HPA), The Cancer Genome Atlas (TCGA), University of California, Santa Cruz Xena (UCSC XENA), Genotype-Tissue Expression (GTEx), MethSurv, The University of Alabama at Birmingham CANcer data analysis Portal (UALCAN), cBioPortal, STRING and TISIDB detabases, followed by enrichment analysis using R software.

RESULTS

GPER1 was widely expressed in tissues and organs and differed in expression from normal tissue in a variety of cancers. In diagnostic assessment, it's Area Under the Curve (AUC) surpassed 0.9 in nine cancer types. Survival analysis showed that GPER1 was correlated with the prognosis of 11 cancer types. Moreover, GPER1 expression was associated with immune infiltration in multiple cancers.

CONCLUSIONS

In summary, GPER1 has good diagnostic or prognostic value across various malignancies. Together with its extensive correlation with immune components, the aforementioned results suggests that GPER1 shows promise in tumour diagnosis and prognosis, providing new ideas for precise and personalised anti-tumour strategies.

GPER induces mitochondrial fission through p44/42 MAPK - Drp1 pathway in breast cancer cells

Understanding GPER biology in breast cancer is rather limited in compassion to the classic estrogen receptors. Mitochondrial dynamics play a critical role in determining cell survival and death under various microenvironmental conditions. We present evidence that GPER-induce mitochondrial fission in breast cancer cells. GPER mediated mitochondrial fission through activating Drp1 by phosphorylating S616 residue and down-regulates fusion proteins Mfn1 and Mfn2 levels. GPER-induced Drp1 activation mediated by p44/42 MAPK and inhibition of this signalling axis completely reverse the mitochondrial fission induced by GPER. Further, mitochondrial fission is required for GPER-induced cell death in breast cancer cells. To conclude, GPER induces mitochondrial fission through p44/42 MAPK - Drp1 signalling, and mitochondrial fission is critical for GPER-induced cell death in breast cancer cells. GENERAL SIGNIFICANCE: First time we report GPER's role in mitochondrial dynamics in cancer cells. Mitochondrial dynamics play a critical role in cancer progression including tamoxifen resistance. Exploring a detailed mechanistic understanding of GPER signalling may help to design new therapy for advanced cancers.

Tamoxifen modulates mitochondrial dynamics through AMPK and MAPK during nutrition deprivation

The interaction of cancer cells with their tumor microenvironment determines key events in the progression of the disease, therapeutic efficacy, and the development of drug resistance. Here, we presented evidence that tamoxifen support breast cancer growth during nutrition deprivation by modulating mitochondrial dynamics through AMPK and MAPK signaling. Tamoxifen enhances mitochondrial fusion under nutrition-deprived conditions by suppressing Drp1 ser616 phosphorylation and upregulating Mfn1 levels. Tamoxifen-induced mitochondrial fusion is mediated by the activation of AMPK as evident by the pharmacological inhibition of AMPK reverse mitochondrial fusion. Interestingly, JNK activation by tamoxifen controls the mitochondrial fusion morphology by downregulating Mfn2. Collectively, tamoxifen support cell growth by enhancing mitochondrial fusion by regulating stress kinase signaling under nutrition deprivation condition.

Estrogen/ER in anti-tumor immunity regulation to tumor cell and tumor microenvironment

As the essential sexual hormone, estrogen and its receptor has been proved to participate in the regulation of autoimmunity diseases and anti-tumor immunity. The adjustment of tumor immunity is related to the interaction between cancer cells, immune cells and tumor microenvironment, all of which is considered as the potential target in estrogen-induced immune system regulation. However, the specific mechanism of estrogen-induced immunity is poorly understood. Typically, estrogen causes the nuclear localization of estrogen/estrogen receptor complex and alternates the transcription pattern of target genes, leading to the reprogramming of tumor cells and differentiation of immune cells. However, the estrogen-induced non-canonical signal pathway activation is also crucial to the rapid function of estrogen, such as NF-κB, MAPK-ERK, and β-catenin pathway activation, which has not been totally illuminated. So, the investigation of estrogen modulatory mechanisms in these two manners is vital for the tumor immunity and can provide the potential for endocrine hormone targeted cancer immunotherapy. Here, this review summarized the estrogen-induced canonical and non-canonical signal transduction pathway and aimed to focus on the relationship among estrogen and cancer immunity as well as immune-related tumor microenvironment regulation. Results from these preclinical researches elucidated that the estrogen-target therapy has the application prospect of cancer immunotherapy, which requires the further translational research of these treatment strategies.

G protein-coupled estrogen receptor 1 (GPER-1) and agonist G-1 inhibit growth of ovarian cancer cells by activation of anti-tumoral transcriptome responses: impact of GPER-1 mRNA on survival

PURPOSE

The present study intended to further elucidate the role of G protein-coupled estrogen receptor 1 (GPER-1) in ovarian cancer by comparing the effects of a GPER-1 knockdown and treatment with its agonist G-1 on cell growth, apoptosis, and the transcriptome of two ovarian cancer cell lines. Furthermore, the role of GPER-1 in ovarian cancer survival was examined.

METHODS

GPER-1 expression in OVCAR-3 and OAW-42 ovarian cancer cells was knocked down by RNAi. The effects on cell growth were measured by means of the fluorimetric cell titer blue assay and on the transcriptome by Affymetrix GeneChip analysis. The effect of GPER-1 on patient's survival was examined using open source mRNA and clinical data of 1657 ovarian cancer patients.

RESULTS

GPER-1 knockdown resulted in a significant growth stimulation of both cell lines, whereas treatment with agonist G-1 decreased growth of both cell lines in a dose-dependent manner. Transcriptome analyses revealed a set of 18 genes being conversely regulated after GPER-1 knockdown and G-1 treatment. Generally, treatment with G-1 led to a transcriptome response associated with growth inhibition. In contrast, knockdown of GPER-1 exerted opposite effects, stimulating pathways activating mitosis, but inhibiting pathways associated with apoptosis or interferon signaling. Further analyses using open-access mRNA and clinical data by bioinformatical online tools revealed a longer OS (HR = 0.86, p = 0.057) and PFS (HR = 0.81, p = 0.0035) of ovarian cancer patients with high GPER-1 mRNA expression.

CONCLUSIONS

The results of this study clearly support the hypothesis that GPER-1 acts as a tumor suppressor in ovarian cancer.

Expression and Role of the G Protein-Coupled Estrogen Receptor (GPR30/GPER) in the Development and Immune Response in Female Reproductive Cancers

Cancer is a major public health issue and represents the second leading cause of death in women worldwide, as female reproductive-related neoplasms are the main cause of incidence and mortality. Female reproductive cancers have a close relationship to estrogens, the principal female sex steroid hormones. Estrogens exert their actions by the nuclear estrogen receptor alpha (ERα) and estrogen receptor beta (ERβ). ERα, and ERβ act as transcription factors mediating genomic effects. Besides, the G protein-coupled estrogen receptor (GPER, formerly known as GPR30) was recently described as a seven-transmembrane receptor that mediates non-genomic estrogenic signaling, including calcium mobilization, cAMP synthesis, cleavage of matrix metalloproteinases, transactivation of epidermal growth factor receptor (EGFR), and the subsequent activation of PI3K and MAPK signaling pathways, which are the reasons why it is related to cellular processes, such as cell-cycle progression, cellular proliferation, differentiation, apoptosis, migration, and invasion. Since its discovery, selective agonists and antagonists have been found and developed. GPER has been implicated in a variety of hormone-responsiveness tumors, such as breast, endometrial, ovarian, cervical, prostate, and testicular cancer as well as lung, hepatic, thyroid, colorectal, and adrenocortical cancers. Nevertheless, GPER actions in cancer are still debatable due to the conflicting information that has been reported to date, since many reports indicate that activation of this receptor can modulate carcinogenesis. In contrast, many others show that its activation inhibits tumor activity. Besides, estrogens play an essential role in the regulation of the immune system, but little information exists about the role of GPER activation on its modulation within cancer context. This review focuses on the role that the stimulation of GPER plays in female reproductive neoplasms, specifically breast, endometrial, ovarian, and cervical cancers, in its tumor activity and immune response regulation.

G protein-coupled estrogen receptor in colon function, immune regulation and carcinogenesis

Estrogens play important roles in the development and progression of multiple tumor types. Accumulating evidence points to the significance of estrogen action not only in tumors of hormonally regulated tissues such as the breast, endometrium and ovary, but also in the development of colorectal cancer (CRC). The effects of estrogens in physiological and pathophysiological conditions are mediated by the nuclear estrogen receptors α and β, as well as the membrane-bound G protein-coupled estrogen receptor (GPER). The roles of GPER in CRC development and progression, however, remain poorly understood. Studies on the functions of GPER in the colon have shown that this estrogen receptor regulates colonic motility as well as immune responses in CRC-associated diseases, such as Crohn’s disease and ulcerative colitis. GPER is also involved in cell cycle regulation, endoplasmic reticulum stress, proliferation, apoptosis, vascularization, cell migration, and the regulation of fatty acid and estrogen metabolism in CRC cells. Thus, multiple lines of evidence suggest that GPER may play an important role in colorectal carcinogenesis. In this review, we present the current state of knowledge regarding the contribution of GPER to colon function and CRC.

Protective role and related mechanism of Gnaq in neural cells damaged by oxidative stress

Gnaq is a member of G protein family and is rich in brain tissue. It has attracted the attention of many researchers in melanoma due to its high ratio of mutation. We have previously reported that the expression level of Gnaq in the mouse forebrain cortex was significantly decreased with age. Oxidative stress (OS) is the main cause leading to brain aging and related diseases. The roles and mechanisms of Gnaq in antioxidation in the brain have not been fully explored. In the present study, gene recombinant technique and lentivirus transfection technique were used to generate a Gnaq-overexpression cell model (Gnaq-SY5Y) coupled with H2O2 to build an OS model. The viability of cells, concentration of reactive oxygen species (ROS), apoptosis-related proteins (Bcl-2 and Bax), and signal pathways (NF-κB and Erk1/2) were compared between model cells and control cells. Results showed that the antioxidative ability of Gnaq-SY5Y cells was significantly improved. Concomitantly, the ROS level in Gnaq-SY5Y cells was significantly decreased whether the cells were subject to or not to H2O2 treatment. Anti-apoptotic protein Bcl-2 was up-regulated and apoptosis-promoting protein Bax was down-regulated in Gnaq-SY5Y cells after treatment with H2O2. NF-κB and phosphorylated Erk1/2 (p-Erk1/2) was significantly down-regulated in Gnaq-SY5Y cells. H2O2 treatment decreased Gnaq expression but increased NF-κB and p-Erk1/2 expressions in Gnaq-SY5Y cells. It is therefore concluded that Gnaq plays a pivotal role in antioxidation in neural cells. A possible mechanism for this would be that the overexpressed Gnaq inhibits the cellular damaging effect mediated by NF-κB and Erk1/2 signal pathways.

GLUL Promotes Cell Proliferation in Breast Cancer

Glutamate-ammonia ligase (GLUL) belongs to the glutamine synthetase family. It catalyzes the synthesis of glutamine from glutamate and ammonia in an ATP-dependent reaction. Here, we found higher expression of GLUL in the breast cancer patients was associated with larger tumor size and higher level of HER2 expression. In addition, GLUL was heterogeneously expressed in various breast cancer cells. The mRNA and protein expression levels of GLUL in SK-BR-3 cells were obviously higher than that in the other types of breast cancer cells. Results showed GLUL knockdown in SK-BR-3 cells could significantly decrease the proliferation ability. Furthermore, GLUL knockdown markedly inhibited the p38 MAPK and ERK1/ERK2 signaling pathways in SK-BR-3 cells. Thus, GLUL may represent a novel target for selectively inhibiting p38 MAPK and ERK1/ERK2 signaling pathways and the proliferation potential of breast cancer cells. J. Cell. Biochem. 118: 2018-2025, 2017. © 2016 Wiley Periodicals, Inc.