Nuclear Receptors Are Differentially Expressed and Activated in KAIMRC1 Compared to MCF7 and MDA-MB231 Breast Cancer Cells

Role of PAX2 in breast cancer verified by bioinformatics analysis and in vitro validation

Background

Breast cancer (BC) is the most frequently diagnosed cancer in women and the second most common cancer among newly diagnosed cancers worldwide. Studies have shown that paired box 2 (PAX2) participates in the tumorigenesis of some cancer cells, but its role in BC is still unclear.

Methods

Transcriptome expression profiles and clinicopathological information of BC were downloaded from The Cancer Genome Atlas (TCGA) database to explore the expression level and prognostic value of PAX2. Gene set enrichment analysis (GSEA) and functional enrichment analysis were performed to investigate the functions and pathways of PAX2. Moreover, real-time reverse transcriptase-polymerase chain reaction (RT-qPCR) was used to determine the expression of PAX2 in BC tissues, and the predictive value of PAX2 in clinical samples was assessed. Cell Counting Kit-8 (CCK-8) assay was used to evaluate cell growth. The migration and invasive capacities of cells were assessed by wound healing assay and Transwell assay.

Results

PAX2 was upregulated in the TCGA-BC datasets. GSEA suggested that PAX2 may be involved in the regulation of signaling pathways such as MAPK. Moreover, PAX2 was overexpressed in BC tissues, and PAX2 expression was associated with tumor size and lymph node metastasis. PAX2 deficiency could promote the growth, migration, and invasion of BC cells.

Conclusions

Upregulation of PAX2 inhibited BC cell growth, migration, and invasion, making PAX2 a potential therapeutic target for BC.

The Role of Glucocorticoids in Breast Cancer Therapy

Glucocorticoids (GCs) are anti-inflammatory and immunosuppressive steroid molecules secreted by the adrenal gland and regulated by the hypothalamic-pituitary-adrenal (HPA) axis. GCs present a circadian release pattern under normal conditions; they increase their release under stress conditions. Their mechanism of action can be via the receptor-independent or receptor-dependent pathway. The receptor-dependent pathway translocates to the nucleus, where the ligand-receptor complex binds to specific sequences in the DNA to modulate the transcription of specific genes. The glucocorticoid receptor (GR) and its endogenous ligand cortisol (CORT) in humans, and corticosterone in rodents or its exogenous ligand, dexamethasone (DEX), have been extensively studied in breast cancer. Its clinical utility in oncology has mainly focused on using DEX as an antiemetic to prevent chemotherapy-induced nausea and vomiting. In this review, we compile the results reported in the literature in recent years, highlighting current trends and unresolved controversies in this field. Specifically, in breast cancer, GR is considered a marker of poor prognosis, and a therapeutic target for the triple-negative breast cancer (TNBC) subtype, and efforts are being made to develop better GR antagonists with fewer side effects. It is necessary to know the type of breast cancer to differentiate the treatment for estrogen receptor (ER)-positive, ER-negative, and TNBC, to implement therapies that include the use of GCs.

Identification and characterization of alternative splicing variants of buffalo LXRα expressed in mammary gland

Liver X receptor α (LXRα) is a ligand-dependent transcription factor and plays an important role in the regulation of cholesterol homeostasis, fatty acid biosynthesis and glucose metabolism. In this study, transcripts of LXRα gene were cloned and characterized from buffalo mammary gland, and three alternative splicing transcripts of buffalo LXRα gene were identified, named LXRα1, LXRα2 and LXRα3. The structure of the LXRα transcripts of buffalo and cattle was highly similar. Bioinformatics analysis showed that LXRα1 contains two complete functional domains of LXRα, one is the DNA-binding domain (NR_DBD_LXR) and the other is the ligand-binding domain (NR_LBD_LXR). The reading frame of LXRα2 is altered due to the skipping of exon 9, which truncates its encoding protein prematurely at the 400th amino acid residue, making it contain a complete DNA-binding domain and part of a ligand-binding domain. Due to the deletion of exon 4, the protein encoded by LXRα3 lacks 89 amino acid residues and contains only a complete ligand-binding domain, which makes it lose its transcriptional regulation function. In addition, motifs and conserved domains of three LXRα variants of buffalo were highly consistent with those of corresponding transcripts from other mammal species. Subcellular localization analysis showed that LXRα1 plays a functional role in the nucleus of buffalo mammary epithelial cells, while LXRα2 and LXRα3 are distributed in the nucleus and cytoplasm. Compared with non-lactating period, the mRNA abundance of the three LXRα transcripts in the mammary gland tissue of buffalo increased during lactating period, revealing that they play a key role in the synthesis of buffalo milk fat. Among the three LXRα transcripts, LXRα1 has the highest expression in the mammary gland, indicating that it is the major transcript in the mammary gland and has important regulatory functions, while LXRα2 and LXRα3 may have regulatory effects on the function of LXRα1. This study highlights the key role of LXRα alternative splicing in the post-transcriptional regulation of buffalo lactation.

New Born Calf Serum Can Induce Spheroid Formation in Breast Cancer KAIMRC1 Cell Line

Three-dimensional (3D) cell culture systems have become very popular in the field of drug screening and discovery. There is an immense demand for highly efficient and easy methods to produce 3D spheroids in any cell format. We have developed a novel and easy method to produce spheroids from the newly isolated KAIMRC1 cell line in vitro. It can be used as a 3D model to study proliferation, differentiation, cell death, and drug response of cancer cells. Our procedure requires growth media supplemented with 10% new born calf serum (NBCS) and regular cell culture plates to generate KAIMRC1 spheroids without the need for any specialized 3D cell culture system. This procedure generates multiple spheroids within a 12–24-h culture. KAIMRC1 spheroids are compact, homogeneous in size and morphology with a mean size of 55.8 µm (±3.5). High content imaging (HCI) of KAIMRC1 spheroids treated with a panel of 240 compounds resulted in the identification of several highly specific compounds towards spheroids. Immunophenotyping of KAIMRC1 spheroids revealed phosphorylation of FAK, cJUN, and E-cadherin, which suggests the involvement of JNK/JUN pathway in the KAIMRC1 spheroids formation. Gene expression analysis showed upregulation of cell junction genes, GJB3, DSC1, CLDN5, CLDN8, and PLAU. Furthermore, co-culture of KAIMRC1 cells with primary cancer-associated-fibroblasts (CAFs) showcased the potential of these cells in drug discovery application.

Discovery of a novel potentially transforming somatic mutation in CSF2RB gene in breast cancer

The colony stimulating factor 2 receptor subunit beta (CSF2RB) is the common signaling subunit of the cytokine receptors for IL-3, IL-5, and GM-CSF. Several studies have shown that spontaneous and random mutants of CSF2RB can lead to ligand independence in vitro. To date, no report(s) have been shown for the presence of potentially transforming and oncogenic CSF2RB mutation(s) clinically in cancer patients until the first reported case of a leukemia patient in 2016 harboring a germline-activating mutation (R461C). We combined exome sequencing, pathway analyses, and functional assays to identify novel somatic mutations in KAIMRC1 cells and breast tumor specimen. The patient's peripheral blood mononuclear cell (PBMC) exome served as a germline control in the identification of somatic mutations. Here, we report the discovery of a novel potentially transforming and oncogenic somatic mutation (S230I) in the CSF2RB gene of a breast cancer patient and the cell line, KAIMRC1 established from her breast tumor tissue. KAIMRC1 cells are immortalized and shown to survive and proliferate in ligand starvation condition. Immunoblot analysis showed that mutant CSF2RB signals through JAK2/STAT and PI3K/mTOR pathways in ligand starvation conditions. Screening a small molecule kinase inhibitor library revealed potent JAK2 inhibitors against KAIMRC1 cells. We, for the first time, identified a somatic, potentially transforming, and oncogenic CSF2RB mutation (S230I) in breast cancer patients that seem to be an actionable mutation leading to the development of new therapeutics for breast cancer.

Metabolites Profiling, In Vitro, In Vivo, Computational Pharmacokinetics and Biological Predictions of Aloe perryi Resins Methanolic Extract

Background: Aloe perryi is a traditional herb that has various biological and pharmacological properties such as anti-inflammatory, laxative, antiviral, antidiabetic, and antitumor effects, which have not been deliberated before. The current investigation aims to evaluate in vitro cytotoxicity against several cancer cell lines in addition to in vivo anti-inflammatory activities of Aloe perryi extract using a rat animal model. Moreover, the pharmacokinetic properties of bioactive constituents and possible biological targets were assessed and evaluated. The methanolic extract of Aloe perryi was prepared by maceration, to tentatively identify the biomolecules of the Aloe perryi extract, analytical LC–QTOF-MS method was employed for Aloe perryi methanolic extract. The cytotoxic activity was examined in six cancer cell lines using Titer-Glo assay and the IC_50s were calculated in addition to in silico target predictions and in vivo anti-inflammatory activity assessment. Subsequently, the pharmacokinetics of the identified active components of Aloe perryi were predicted using SwissADME, and target prediction using the Molinspiration webserver. The cytotoxic activity on HL60 and MDA-MB-231 was moderately affected by the Aloe perryi extract with IC₅₀ of 63.81, and 89.85 μg/mL, respectively, with no activity on other cells lines. Moreover, the Aloe perryi extract exhibited a significant increase in wound contraction, hair growth, and complete re-epithelization when compared with the negative control. The pharmacokinetic properties of the bioactive constituents suggested a good pharmaceutical profile for the active compounds and nuclear receptors and enzymes were the two main possible targets for these active compounds. Our results demonstrated the promising activity of Aloe perryi extract with cytotoxic and anti-inflammatory properties, indicating a potential therapeutic utility of this plant in various disease conditions.