Advances in immune regulation of the G protein-coupled estrogen receptor.

Estrogen and related receptors have been shown to have a significant impact on human development, reproduction, metabolism and immune regulation and to play a critical role in tumor development and treatment. Traditionally, the nuclear estrogen receptors (nERs) ERα and ERß have been thought to be involved in mediating the estrogenic effects. However, our group and others have previously demonstrated that the G protein-coupled estrogen receptor (GPER) is the third independent ER, and estrogen signaling mediated by GPER is known to play an important role in normal physiology and a variety of abnormal diseases. Interestingly, recent studies have progressively revealed GPER involvement in the maintenance of the normal immune system, abnormal immune diseases, and inflammatory lesions, which may be of significant clinical value primarily in the immunotherapy of tumors. In this article, we review current advances in GPER-related immunomodulators and provide a theoretical basis and potential clinical targets to ameliorate immune-related diseases and immunotherapy for tumors.

Prognostic and risk factor analysis of cancer patients after unplanned ICU admission: a real-world multicenter study.

To investigate the occurrence and 90-day mortality of cancer patients following unplanned admission to the intensive care unit (ICU), as well as to develop a risk prediction model for their 90-day prognosis. We prospectively analyzed data from cancer patients who were admitted to the ICU without prior planning within the past 7 days, specifically between May 12, 2021, and July 12, 2021. The patients were grouped based on their 90-day survival status, and the aim was to identify the risk factors influencing their survival status. A total of 1488 cases were included in the study, with an average age of 63.2 ± 12.4 years. The most common reason for ICU admission was sepsis (n = 940, 63.2%). During their ICU stay, 29.7% of patients required vasoactive drug support (n = 442), 39.8% needed invasive mechanical ventilation support (n = 592), and 82 patients (5.5%) received renal replacement therapy. We conducted a multivariate COX proportional hazards model analysis, which revealed that BMI and a history of hypertension were protective factors. On the other hand, antitumor treatment within the 3 months prior to admission, transfer from the emergency department, general ward, or external hospital, high APACHE score, diagnosis of shock and respiratory failure, receiving invasive ventilation, and experiencing acute kidney injury (AKI) were identified as risk factors for poor prognosis within 90 days after ICU admission. The average length of stay in the ICU was 4 days, while the hospital stay duration was 18 days. A total of 415 patients died within 90 days after ICU admission, resulting in a mortality rate of 27.9%. We selected 8 indicators to construct the predictive model, which demonstrated good discrimination and calibration. The prognosis of cancer patients who are unplanned transferred to the ICU is generally poor. Assessing the risk factors and developing a risk prediction model for these patients can play a significant role in evaluating their prognosis.

Role of G Protein-Coupled Estrogen Receptor in Digestive System Carcinomas: A Minireview.

Digestive system carcinomas are one of the leading causes of cancer-related deaths worldwide. G protein-coupled estrogen receptor (GPER), a novel estrogen receptor, has been recognized as an important mediator in numerous cancer types. Recently, the function and clinical significance of GPER in digestive system carcinomas has been a subject of interest. Increasing evidence has revealed that GPER plays an important role as a potential biomarker in digestive system carcinomas. This work summarizes the recent literature and focuses on the emerging functional role of GPER in digestive system carcinomas, including gastric cancer, hepatocellular carcinoma, pancreatic cancer, and colorectal cancer. The potential application of GPER in novel strategies for the diagnosis and treatment of digestive system carcinomas is discussed and highlighted.

GPER-Induced ERK Signaling Decreases Cell Viability of Hepatocellular Carcinoma.

Hepatocellular carcinoma (HCC) is an aggressive malignancy with a poor prognosis. Effective biomarkers and specific therapeutic targets for HCC are therefore urgently needed. G protein-coupled estrogen receptor (GPER) plays a crucial role in numerous cancer types; however, its functions in HCC require further exploration. In the present study, we found a remarkable difference in GPER staining between tumor tissue (100/141, 70.9%) and matched non-tumor tissue (27/30, 90.0%). Compared with the GPER-negative patients, the GPER-positive patients with HCC were closely associated with female sex, negative hepatitis B surface antigen, small tumor size, low serum alpha fetoprotein level, and longer overall survival. Treatment with GPER-specific agonist G1 led to the sustained and transient activation of the EGFR/ERK and EGFR/AKT signaling pathways, respectively, in the HCC cell lines HCCLM3 and SMMC-7721, which express high levels of GPER. Interestingly, G1-induced EGFR/ERK signaling, rather than EGFR/AKT signaling mediated by GPER, was involved in decreasing cell viability by blocking cell cycle progression, thereby promoting apoptosis and inhibiting cell growth. Clinical analysis indicated that simultaneous high expression of GPER and phosphorylated-ERK (p-ERK) predicted improved prognosis for HCC. Finally, the activation of GPER/ERK signaling remarkably suppressed tumor growth in an HCC xenograft model, and this result was consistent with the in vitro data. Our findings suggest that specific activation of the GPER/ERK axis may serve as a novel tumor-suppressive mechanism and that this axis could be a therapeutic target for HCC.

GPER mediates decreased chemosensitivity via regulation of ABCG2 expression and localization in tamoxifen-resistant breast cancer cells.

Rescue chemotherapy is usually the preferred treatment for patients with advanced estrogen receptor-positive (ER+) breast cancer with endocrinotherapy resistance. However, these patients often simultaneously show a poor response to cytotoxic drugs, and thus the detailed mechanism of this resistance needs to be further investigated. Our previous research indicated that the G-protein-coupled estrogen receptor (GPER) is a novel mediator of the development of multidrug resistance, including resistance to both endocrinotherapy and chemotherapy, and ATP binding cassette subfamily G member 2 (ABCG2) has been identified as an engine that confers cancer cells with chemoresistance by expelling xenobiotics and chemotherapeutics. Here, we are the first to show that the expression levels of GPER and ABCG2 are markedly increased in tamoxifen-resistant ER + metastases compared to the corresponding primary tumors. A plasma membrane expression pattern of GPER and ABCG2 was observed in patients with metastases. Furthermore, both ER modulator tamoxifen, GPER-specific agonist G1 and pure ER antagonist ICI 182,780 significantly enhanced ABCG2 expression in tamoxifen-resistant breast cancer cells (MCF-7R) but not in tamoxifen-sensitive cells (MCF-7). The activated downstream GPER/EGFR/ERK and GPER/EGFR/AKT signaling pathways were responsible for regulating the expression and cell membrane localization of ABCG2, respectively, in MCF-7R cells. Interestingly, the above phenomenon could be alleviated by inhibitors of both the indicated signaling pathways and by knockdown of GPER in MCF-7R cells. More importantly, the tamoxifen-induced GPER/ABCG2 signaling axis was shown to play a pivotal role in the development of chemotherapy (doxorubicin) resistance both in vitro and in vivo. The clinical data further revealed that tamoxifen-resistant patients with high GPER/ABCG2 signaling activation had poor progression-free survival (PFS) when given rescue anthracycline chemotherapy. Therefore, our data provide novel insights into GPER-mediated chemoresistance and provide a rationale for the GPER/ABCG2 signaling axis being a promising target for reversing chemoresistance in patients with advanced ER + tamoxifen-resistant breast cancer.