Downregulation of regulator of G protein signaling 2 expression in breast invasive carcinoma of no special type: Clinicopathological associations and prognostic relevance

Characterization of immune landscape and prognostic value of IL-17-related signature in invasive breast cancer

Background

Recently, interleukin 17 (IL-17) has been found to play a critical role in the development of breast cancer. However, its prognostic significance in invasive breast cancer (IBC) remains unclear. This study aims to determine the role of IL-17-related signatures in IBC to identify novel therapeutic options.

Methods

IBC data from The Cancer Genome Atlas (TCGA), Gene Expression Omnibus (GEO), and Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) were used to identify IL-17-related prognostic genes. A predictive model was developed using TCGA data and validated using METABRIC data. The relationship between IL-17 scores and immune landscape, chemotherapy drug sensitivity [half maximal inhibitory concentration (IC50)], and immune checkpoint gene expression was analyzed. The quantitative reverse transcription polymerase chain reaction (qRT-PCR) was performed to validate key gene expression in breast tumor and normal tissue samples.

Results

The predictive model identified core IL-17-related prognostic genes and successfully estimated the prognosis of IBC patients. The model's validity was confirmed using METABRIC data. Patients with high IL-17 scores had worse overall survival (OS) compared to those with low IL-17 scores. Low IL-17 scores were associated with higher immune checkpoint gene expression and predicted enhanced responses to cytotoxic T-lymphocyte-associated protein 4 (CTLA4) and programmed cell death protein 1 (PD-1) therapies. Patients with low IL-17 scores exhibited a higher abundance of immune microenvironment components. Furthermore, qRT-PCR confirmed the lower expression of OR51E1, NDRG2, RGS2, and TSPAN7 in breast tumors compared to normal tissue.

Conclusions

IL-17-related signatures are promising biomarkers for predicting the prognosis of IBC patients. These findings suggest that IL-17-related markers could be used to guide individualized therapeutic strategies, potentially improving outcomes for IBC patients.

LINC01140 Targeting miR-452-5p/RGS2 Pathway to Attenuate Breast Cancer Tumorigenesis

Background

LINC01140 has been known to be involved in various cancers. However, its underlying molecular mechanism in breast cancer (BC) needs further exploration.

Methods

The LINC01140, miR-452-5p, and RGS2 levels in BC cells and tissues were evaluated by means of RT-qPCR and western blotting. The variations in the biological functions of BC cells were analyzed through CCK-8, transwell, western blotting, and xenograft experiments to observe cell viability, migration, levels of apoptosis-related proteins (Bax and Bcl-2), and tumor growth. The correlations existing among LINC01140, miR-452-5p, and RGS2 were validated through luciferase reporter and RIP assays.

Results

LINC01140 and RGS2 were remarkably downregulated in BC cells and tissues, whereas miR-452-5p was upregulated. LINC01140 overexpression diminished BC cell viability, migration, and tumor growth and facilitated apoptosis. MiR-452-5p upregulation enhanced cell viability and migration and suppressed apoptosis. Nevertheless, the additional upregulation of LINC01140 could reverse the promotive effects of miR-452-5p upregulation. Additionally, RGS2 overexpression inhibited the malignant phenotypes of BC cells, but miR-452-5p upregulation abolished this effect. In terms of mechanisms, LINC01140 acted as a miR-452-5p sponge. Moreover, RGS2 was determined to be miR-452-5p's downstream target gene in BC.

Conclusion

LINC01140 functioned as an antitumor agent in BC by sponging miR-452-5p to release RGS2. This hints that LINC01140 is a promising therapeutic target for BC.

Low Expression of RGS2 Promotes Poor Prognosis in High-Grade Serous Ovarian Cancer

Simple Summary

Recent advances in molecular medicine have indicated G-protein coupled receptors (GPCRs) as possible therapeutic targets in ovarian cancer. The cellular effects of GPCRs are determined by regulator of G protein signaling (RGS) proteins. Especially RGS2 has currently moved into focus of cancer therapy. Therefore, we retrospectively analyzed RGS2 and its association with the prognosis of high-grade serous ovarian cancer (HGSOC). Here, we provide in situ and in silico analyses regarding the expression patterns and prognostic value of RGS2. In silico we found that RGS2 is barely detectable in tumor cells on the mRNA level in bulk and single-cell data. Applying immunohistochemistry in 519 HGSOC patients, we detected moderate to strong protein expression of RGS2 in situ in approximately half of the cohort, suggesting regulation by post translational modification. Furthermore, low protein expression of RGS2 was associated with an inferior overall- and progression-free survival. These results warrant further research of its role and related new therapeutic implications in HGSOC.

Abstract

RGS2 regulates G-protein signaling by accelerating hydrolysis of GTP and has been identified as a potentially druggable target in carcinomas. Since the prognosis of patients with high-grade serous ovarian carcinoma (HGSOC) remains utterly poor, new therapeutic options are urgently needed. Previous in vitro studies have linked RGS2 suppression to chemoresistance in HGSOC, but in situ data are still missing. In this study, we characterized the expression of RGS2 and its relation to prognosis in HGSOC on the protein level by immunohistochemistry in 519 patients treated at Charité, on the mRNA level in 299 cases from TCGA and on the single-cell level in 19 cases from publicly available datasets. We found that RGS2 is barely detectable on the mRNA level in both bulk tissue (median 8.2. normalized mRNA reads) and single-cell data (median 0 normalized counts), but variably present on the protein level (median 34.5% positive tumor cells, moderate/strong expression in approximately 50% of samples). Interestingly, low expression of RGS2 had a negative impact on overall survival (p = 0.037) and progression-free survival (p = 0.058) on the protein level in lower FIGO stages and in the absence of residual tumor burden. A similar trend was detected on the mRNA level. Our results indicated a significant prognostic impact of RGS2 protein suppression in HGSOC. Due to diverging expression patterns of RGS2 on mRNA and protein levels, posttranslational modification of RGS2 is likely. Our findings warrant further research to unravel the functional role of RGS2 in HGSOC, especially in the light of new drug discovery.

The Association of RGS2 and Slug in the Androgen-induced Acquisition of Mesenchymal Features of Breast MDA-MB-453 Cancer Cells

BACKGROUND

Epithelial-mesenchymal transition (EMT) of tumor cells is a prerequisite to cancer cell invasion and metastasis. This process involves a network of molecular alterations. Androgen receptor (AR) plays an important role in the biology of breast cancers, particularly those dependent on AR expression like luminal AR (LAR) breast cancer subtype. We have recently reported that the AR agonist, dihydrotestosterone (DHT), induces a mesenchymal transition of MDA-MB-453 cells, concomitant with transcriptional up-regulation of Slug and regulator of G protein signaling 2 (RGS2).

OBJECTIVE

The role of Slug and RGS2 in mediating the DHT-induced effects in these cells was investigated.

METHODS

MDA-MB-453 cells were used as a model system of LAR breast cancer. Immunofluorescence was used to examine cell morphology and protein localization. Protein expression was analyzed by immunoblotting. Protein localization was confirmed by cell fractionation followed by immunoblotting. Protein-protein interaction was confirmed by co-immunoprecipitation followed by immunoblotting. Transwell membranes were used to assess cell migration. Transfection of cells with siRNA molecules that target Slug and RGS2 mRNA was utilized to delineate the modes of action of these two molecules.

RESULTS

Treatment of MDA-MB-453 cells with DHT induced the expression of both proteins. In addition, AR-Slug, AR-RGS2, and Slug-RGS2 interactions were observed shortly after AR activation. Knocking down Slug abrogated the basal, but not the DHT-induced, cell migration and blocked DHT-induced mesenchymal transition. On the other hand, RGS2 knocked-down cells had an increased level of Slug protein and assumed mesenchymal cell morphology with induced migration, and the addition of DHT further elongated cell morphology and stimulated their migration. Inhibition of AR or β-catenin reverted the RGS2 knocked-down cells to the epithelial phenotype, but only inhibition of AR blocked their DHT-induced migration.

CONCLUSIONS

These results suggest the involvement of RGS2 and Slug in a complex molecular network regulating the DHT-induced mesenchymal features in MDA-MB-453 cells. The study may offer a better understanding of the biological role of AR in breast cancer toward devising AR-based therapeutic strategies.

Caveolin-1: a multifaceted driver of breast cancer progression and its application in clinical treatment

Human breast cancer is one of the most frequent cancer diseases and causes of death among female population worldwide. It appears at a high incidence and has a high malignancy, mortality, recurrence rate and poor prognosis. Caveolin-1 (Cav1) is the main component of caveolae and participates in various biological events. More and more experimental studies have shown that Cav1 plays a critical role in the progression of breast cancer including cell proliferation, apoptosis, autophagy, invasion, migration and breast cancer metastasis. Besides, Cav1 has been found to be involved in chemotherapeutics and radiotherapy resistance, which are still the principal problems encountered in clinical breast cancer treatment. In addition, stromal Cav1 may be a potential indicator for breast cancer patients' prognosis. In the current review, we cover the state-of-the-art study, development and progress on Cav1 and breast cancer, altogether describing the role of Cav1 in breast cancer progression and application in clinical treatment, in the hope of providing a basis for further research and promoting CAV1 gene as a potential target to diagnose and treat aggressive breast cancers.