β Arrestin inhibition induces autophagy, apoptosis, G0/G1 cell cycle arrest in agonist activated V2R receptor in breast cancer cells

Abstract Non-visual arrestins (β-arrestins) are endocytic proteins that mediate agonist activated GPCRs internalization and signaling pathways in an independent manner. The involvement of β-arrestins in cancer invasion and metastasis is increasingly reported. So, it is hypothesized that inhibition of β-arrstins may diminish the survival chances of cancer cells. This study aimed to evaluate the in vitro impact of inhibiting β-arrestins on the autophagic and/or apoptotic responsiveness of breast cancer cells. We used Barbadin to selectively inhibit β-Arr/AP2 interaction in AVP stimulated V2R receptor of triple negative breast cancer cells (MDA MB-231). Autophagy was assessed by the microtubule-associated protein 1 light chain 3-II (LC3II), apoptosis was measured by Annexin-V/PI staining and cell cycle distribution was investigated based upon the DNA content using flow cytometry. Barbadin reduced cell viability to 69.1% and increased the autophagy marker LC3 II and its autophagic effect disappeared in cells transiently starved in Earle's balanced salt solution (EBSS). Also, Barbadin mildly enhanced the expression of P62 mRNA and arrested 63.7% of cells in G0/G1 phase. In parallel, the drug induced apoptosis in 29.9% of cells (by AV/PI) and 27.8% of cells were trapped in sub-G1 phase. The apoptotic effect of Barbadin was enhanced when autophagy was inhibited by the PI3K inhibitor (Wortmannin). Conclusively, the data demonstrate the dual autophagic and apoptotic effects of β-βArr/AP2 inhibition in triple negative breast cancer cells. These observations nominate β-Arrs as selective targets in breast cancer treatment.

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The Potential Prognostic Role of Oligosaccharide-Binding Fold-Containing Protein 2A (OBFC2A) in Triple-Negative Breast Cancer

Frontiers in Oncology ◽

10.3389/fonc.2021.751430 ◽

2021 ◽

Vol 11 ◽

Author(s):

Qianxue Wu ◽

Xin Tang ◽

Wenming Zhu ◽

Qing Li ◽

Xiang Zhang ◽

...

Keyword(s):

Breast Cancer ◽

Cell Cycle ◽

Cancer Cells ◽

Candidate Genes ◽

Triple Negative Breast Cancer ◽

Breast Cancer Cells ◽

Triple Negative ◽

G1 Phase ◽

And Migration

BackgroundPatients with triple-negative breast cancer (TNBC) have poor overall survival. The present study aimed to investigate the potential prognostics of TNBC by analyzing breast cancer proteomic and transcriptomic datasets.MethodsCandidate proteins selected from CPTAC (the National Cancer Institute’s Clinical Proteomic Tumor Analysis Consortium) were validated using datasets from METABRIC (Molecular Taxonomy of Breast Cancer International Consortium). Kaplan-Meier analysis and ROC (receiver operating characteristic) curve analysis were performed to explore the prognosis of candidate genes. GO (Gene Ontology) and KEGG (Kyoto Encyclopedia of Genes and Genomes) enrichment analysis were performed on the suspected candidate genes. Single-cell RNA-seq (scRNA-seq) data from GSE118389 were used to analyze the cell clusters in which OBFC2A (Oligosaccharide-Binding Fold-Containing Protein 2A) was mainly distributed. TIMER (Tumor Immune Estimation Resource) was used to verify the correlation between OBFC2A expression and immune infiltration. Clone formation assays and wound healing assays were used to detect the role of OBFC2A expression on the proliferation, invasion, and migration of breast cancer cells. Flow cytometry was used to analyze the effects of silencing OBFC2A on breast cancer cell cycle and apoptosis.ResultsSix candidate proteins were found to be differentially expressed in non-TNBC and TNBC groups from CPTAC. However, only OBFC2A was identified as an independently poor prognostic gene marker in METABRIC (HR=3.658, 1.881-7.114). And OBFC2A was associated with immune functions in breast cancer. Biological functional experiments showed that OBFC2A might promote the proliferation and migration of breast cancer cells. The inhibition of OBFC2A expression blocked the cell cycle in G1 phase and inhibited the transformation from G1 phase to S phase. Finally, downregulation of OBFC2A also increased the total apoptosis rate of cells.ConclusionOn this basis, OBFC2A may be a potential prognostic biomarker for TNBC.

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