Protein kinase C-α downregulates estrogen receptor-α by suppressing c-Jun phosphorylation in estrogen receptor-positive breast cancer cells

Identification of key genes involved in tamoxifen-resistant breast cancer using bioinformatics analysis

Background

The purpose of the present study was to investigate the molecular mechanisms of tamoxifen resistance in breast cancer and to identify potential targets for antitamoxifen resistance.

Methods

Differentially expressed genes (DEGs) in tamoxifen-resistant and tamoxifen-sensitive breast cancer cells were assessed using the GSE67916 dataset acquired from the Gene Expression Omnibus database. Gene ontology (GO) and pathway enrichment analyses were applied to investigate the functions and pathways of the DEGs. Subsequently, the protein-protein interaction (PPI) network was constructed using the Search Tool for the Retrieval of Interacting Genes (STRING), and subnetworks were further analyzed by Molecular Complex Detection (MCODE). The PPI network and subnetworks were visualized using Cytoscape software.

Results

In total, 438 DEGs were identified, of which 300 were upregulated and 138 were downregulated. The DEGs were significantly enriched in the protein binding, cellular response to estradiol stimulus, and immune response GO terms while the most significant pathways included the mitogen-activated protein kinase (MAPK) signaling pathway in cancer. The PPI network of DEGs was constructed with 288 nodes and 629 edges, and 2 subnetworks were screened out from the entire network.

Conclusions

A number of significant hub DEGs were identified based on their degree of connectivity in the PPI network, , included MAPK1 (node degree 36), ESR1 (node degree 27), SMARCA4 (node degree 27), RANBP2 (node degree 25), and PRKCA (node degree 21). These critical hub genes were found to be related to tamoxifen resistance in breast cancer. The results of this study further the understanding of tamoxifen resistance at the molecular level and identify potential therapeutic targets for tamoxifen-resistant breast cancer.

Yuanhuacin and Related Anti-Inflammatory and Anticancer Daphnane Diterpenes from Genkwa Flos—An Overview

The dried flower buds of the plant Daphne genkwa Sieb. et Zucc. have been largely used in traditional Chinese medicine for the treatment of inflammatory diseases. Numerous diterpenoids have been isolated from the Genkwa Flos (yuanhua in Chinese), including a series of daphnane-type diterpene designated as yuanhuacin (YC, often improperly designated as yuanhuacine) and analogues with a patronymic name. The series includes ten daphnane-type diterpenes: yuanhuacin, yuanhuadin (YD), yuanhuafin (YF), yuanhuagin (YG), yuanhuahin (YH), yuanhuajin (YJ), yuanhualin (YL), yuanhuamin (YM), yuanhuapin (YP), and yuanhuatin (YT). They are distinct from the rare flavonoid yuanhuanin. The series comprises several anticancer agents, such as the lead compound YC, which has revealed potent activity in vitro and in vivo against models of lung and breast cancers. The main signaling pathways implicated in the antitumor effects have been delineated. Protein kinase C is a key factor of activity for YC, but in general the molecular targets at the origin of the activity of these compounds remain little defined. Promising anticancer effects have been reported with analogues YD and YT, whereas compounds YF and YP are considered more toxic. The pharmacological activity of each compound is presented, as well as the properties of Genkwa Flos extracts. The potential toxic effects associated with the use of these compounds are also underlined.

The role of AKR1 family in tamoxifen resistant invasive lobular breast cancer based on data mining

Background

Tamoxifen (TAM) resistance to invasive lobular cell carcinoma is a challenge for breast cancer treatment. This study explored the role of Aldo-keto reductase family 1 (AKR1) family in tamoxifen-resistant aggressive lobular breast cancer based on data mining.

Methods

TAM-resistant invasive lobular breast cancer gene chip was downloaded from the Gene Expression Omnibus (GEO) database (accession-numbered as GSE96670). The online analytical tool GEO2R was used to screen for differentially expressed genes in TAM-resistant invasive lobular breast cancer cells and TAM-sensitive counterparts. A protein-protein interaction (PPI) networks were constructed using the STRING online platform and the Cytoscape software. GeneMANIA and GSCALite online tools were used to reveal the potential role of these hub genes in breast cancer progression and TAM resistance development. And the used the GSE67916 microarray data set to verify the differentially expression of these hub genes in breast cancer. The protein expression levels of AKR1C1, AKR1C2 and AKR1C3 in TAM-sensitive and resistant breast cancer cells were compared. The TAM sensitivity of breast cancer cells with or without AKR1C1, AKR1C2 or AKR1C3 gene manipulation was evaluated by cell viability assay.

Results

A total of 184 differentially expressed genes were screened. Compared with TAM sensitive breast cancer cells, 162 were up-regulated and 22 were down-regulated. The study identified several hub genes in the PPI network that may be involved in the development of TAM resistance of breast cancer, including signal transducer and activator of transcription 1 (STAT1), estrogen receptor alpha (ESR1), fibronectin1 (FN1), cytochrome P4501B1 (CYP1B1), AKR1C1, AKR1C2, AKR1C3 and uridine diphosphate glucuronosyltransferase (UGT) 1A family genes (UGT1A1, UGT1A3, UGT1A4, UGT1A6, UGT1A7, UGT1A8, UGT1A9, UGT1A10). Compared with TAM-sensitive counterparts, the expression levels of AKR1C1, AKR1C2, and AKR1C3 were up-regulated in TAM-resistant breast cancer cells.

Conclusions

Overexpression of each of these three genes significantly increased the resistance of breast cancer cells to TAM treatment, while their knockdown showed opposite effects, indicating that they are potential therapeutic target for the treatment of TAM-resistant breast cancer.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-09040-8.

A CRISPR/Cas9 zebrafish lamin A/C mutant model of muscular laminopathy

BACKGROUND

Lamin A/C gene (LMNA) mutations frequently cause cardiac and/or skeletal muscle diseases called striated muscle laminopathies. We created a zebrafish muscular laminopathy model using CRISPR/Cas9 technology to target the zebrafish lmna gene.

RESULTS

Heterozygous and homozygous lmna mutants present skeletal muscle damage at 1 day post-fertilization (dpf), and mobility impairment at 4 to 7 dpf. Cardiac structure and function analyses between 1 and 7 dpf show mild and transient defects in the lmna mutants compared to wild type (WT). Quantitative RT-PCR analysis of genes implicated in striated muscle laminopathies show a decrease in jun and nfκb2 expression in 7 dpf homozygous lmna mutants compared to WT. Homozygous lmna mutants have a 1.26-fold protein increase in activated Erk 1/2, kinases associated with striated muscle laminopathies, compared to WT at 7 dpf. Activated Protein Kinase C alpha (Pkc α), a kinase that interacts with lamin A/C and Erk 1/2, is also upregulated in 7 dpf homozygous lmna mutants compared to WT.

CONCLUSIONS

This study presents an animal model of skeletal muscle laminopathy where heterozygous and homozygous lmna mutants exhibit prominent skeletal muscle abnormalities during the first week of development. Furthermore, this is the first animal model that potentially implicates Pkc α in muscular laminopathies.

An HMGA2-p62-ERα axis regulates uterine leiomyomas proliferation

Uterine leiomyomas (ULM) are a major public health issue contributing to high morbidity and poor pregnancy outcomes. However, its molecular pathogenesis is poorly understood. HMGA2-ULM is the second major subtype of human ULM and associates with large sizes, fast-growth, and high percentages of estrogen receptor α (ERα). As altered ERα expression plays a distinct role in ULM growth, here, we investigate a regulatory mechanism driving ULM growth via HMGA2 and ERα. We reveal a positive correlation of HMGA2 with ERα protein and demonstrate that HMGA2 promotes ULM cells proliferation via ERα. In addition, autophagy pathway and p62/SQSTM1 (a selective autophagy receptor) are found to participate in the regulation of HMGA2 and ERα. Moreover, HMGA2 suppresses the transcription of p62 by binding to its promoter, meanwhile, p62 interacts with ERα, and inhibition of p62 increases ERα expression and enhances cell viability in ULM, suggesting a novel mechanism of the HMGA2-p62-ERα axis in ULM proliferation. Notably, rapamycin, a familiar autophagy agonist, reduces ERα levels and the proliferation ability of ULM cells. This study demonstrates a causal role of the HMGA2-p62-ERα axis in preventing autophagy and increasing ERα expression in HMGA2-ULM. Therefore, blocking HMGA2-p62-ERα axis and targeting autophagy pathway establish a roadmap toward HMGA2-ULM medical treatment.

Phosphoproteome profiling reveals critical role of JAK-STAT signaling in maintaining chemoresistance in breast cancer

Breast cancer is responsible for 25% of cancer cases and 15% of cancer death among women. Treatment is usually prolonged and hampered by the development of chemoresistance. The molecular mechanisms maintaining the chemoresistant phenotype remains, however, largely obscure. As kinase signaling in general is highly drugable, identification of kinases essential for maintaining chemoresistance could prove therapeutically useful. Hence we compared cellular kinase activity in chemotherapy resistant MCF7Res cells to chemotherapy-sensitive MCF cells using a peptide array approach that provides an atlas of cellular kinase activities and consequently, predominant pathways can be identified. We observed that peptides phosphorylated by elements of JAK-STAT signaling pathway and PKC signaling pathways are subject to extensive kinase activity in MCF7Res cells as compared to chemotherapy-sensitive MCF cells; and Western blotting confirmed relatively strong activation of these signaling pathways in chemoresistant cells. Importantly, treatment of cells with Tofacitinib, a FDA-approved JAK inhibitor, converted chemoresistant cells to chemosensitive cells, inducing apoptosis when used in conjunction with doxorubicin. Thus our results reveal that chemoresistance in breast cancer is associated with activation of JAK/STAT signaling and suggest that JAK2 may be useful for combating chemoresistance in breast cancer.