rs6426881 in the 3'-UTR of PBX1 is involved in breast and gastric cancers via altering the binding potential of miR-522-3p

PBX1 as a novel master regulator in cancer: Its regulation, molecular biology, and therapeutic applications

PBX1 is a critical transcription factor at the top of various cell fate-determining pathways. In cancer, PBX1 stands at the crossroads of multiple oncogenic signaling pathways and mediates responses by recruiting a broad repertoire of downstream targets. Research thus far has corroborated the involvement of PBX1 in cancer proliferation, resisting apoptosis, tumor-associated neoangiogenesis, epithelial-mesenchymal transition (EMT) and metastasis, immune evasion, genome instability, and dysregulating cellular metabolism. Recently, our understanding of the functional regulation of the PBX1 protein has advanced, as increasing evidence has depicted a regulatory network consisting of transcriptional, post-transcriptional, and post-translational levels of control mechanisms. Furthermore, accumulating studies have supported the clinical utilization of PBX1 as a prognostic or therapeutic target in cancer. Preliminary results showed that PBX1 entails vast potential as a targetable master regulator in the treatment of cancer, particularly in those with high-risk features and resistance to other therapeutic strategies. In this review, we will explore the regulation, protein-protein interactions, molecular pathways, clinical application, and future challenges of PBX1.

Small nucleolar RNA Snora73 promotes psoriasis progression by sponging miR-3074-5p and regulating PBX1 expression

Chronic psoriasis is a kind of immune-mediated skin illness and the underlying molecular mechanisms of pathogenesis remain incompletely understood. Here, we used small RNA microarray assays to scan the differential expressed RNAs in psoriasis patient samples. The downstream miRNAs and its targets were predicted using bioinformatics analysis from online bases and confirmed using fluorescence in situ hybridization and dual‑luciferase report gene assay. Cell ability of proliferation and migration were detected using CCK-8 and transwell assays. The results showed that a new snoRNA Snora73 was upregulated in psoriasis patient samples. Overexpression of Snora73 significantly increased psoriasis cells viability and migration, while knockdown of Snora73 got the opposite results. Mechanistically, our results showed that Snora73 acted as a sponge for miR-3074-5p and PBX1 is a direct target of miR-3074-5p in psoriasis cells. Furthermore, miR-3074-5p suppressed psoriasis cell proliferation and migration, while PBX1 promoted cell proliferation and migration in psoriasis. Collectively, these findings reveal a crucial role of Snora73 in progression of psoriasis through miR-3074-5p/PBX1 signaling pathway and suggest a potential therapeutic strategy.

MiR-522-3p Targets Transcription Factor 4 to Overcome Cisplatin Resistance of Gastric Cells

Gastric cancer (GC) is a malignancy originating from gastric epithelial tissue. Chemoresistance to cisplatin (DDP) often leads to chemotherapy failure in GC. Previously, miR-522 was found to be associated with chemoresistance in GC cells. Thus, we attempted to clarify miR-522-3p's role underlying chemoresistance of GC cells. RT-qPCR measured the miR-522-3p levels in untreated and DDP-treated AGS cells. RT-qPCR and Western blotting detected transcription factor 4 (TCF4) mRNA and protein levels in GC cells. AGS and AGS/DDP cell proliferation were detected by the colony formation assay. Flow cytometry analysis detected AGS and AGS/DDP cell apoptosis. Bioinformatics and dual luciferase reporter assays predicted and verified the relationship between miR-522-3p and TCF4. Rescue experiments further clarified the regulatory patterns of miR-522-3p/TGF4 in GC cells. miR-522-3p presented a downregulation in GC cells and was positively affected by DDP. TCF4 presented elevation in GC cells and was negatively affected by DDP. Mechanistically, miR-522-3p targeted TCF4 to suppress TCF4 gene expression. miR-522-3p overexpression suppressed GC cell proliferation and resistance to DDP and GC cell apoptosis was facilitated. TCF4 overexpression facilitated GC cell proliferation and resistance to DDP while repressing GC cell apoptosis. TCF4 elevation rescued changes in GC cell proliferation, apoptosis, and chemoresistance due to miR-522-3p overexpression. To sum up, miR-522-3p suppresses GC cell malignancy and resistance to DDP via targeting TCF4. Our research may provide a new biomarker for GC diagnosis and a novel direction for GC chemotherapy.

The TALE never ends: A comprehensive overview of the role of PBX1, a TALE transcription factor, in human developmental defects

PBX1 is a highly conserved atypical homeodomain transcription factor (TF) belonging to the TALE (three amino acid loop extension) family. Dimerized with other TALE proteins, it can interact with numerous partners and reach dozens of regulating sequences, suggesting its role as a pioneer factor. PBX1 is expressed throughout the embryonic stages (as early as the blastula stage) in vertebrates. In human, PBX1 germline variations are linked to syndromic renal anomalies (CAKUTHED). In this review, we summarized available data on PBX1 functions, PBX1-deficient animal models, and PBX1 germline variations in humans. Two types of genetic alterations were identified in PBX1 gene. PBX1 missense variations generate a severe phenotype including lung hypoplasia, cardiac malformations, and sexual development defects (DSDs). Conversely, truncating variants generate milder phenotypes (mainly cryptorchidism and deafness). We suggest that defects in PBX1 interactions with various partners, including proteins from the HOX (HOXA7, HOXA10, etc.), WNT (WNT9B, WNT3), and Polycomb (BMI1, EED) families are responsible for abnormal proliferation and differentiation of the embryonic mesenchyme. These alterations could explain most of the defects observed in humans. However, some phenotype variability (especially DSDs) remains poorly understood. Further studies are needed to explore the TALE family in greater depth.

Implication of microRNAs in Carcinogenesis with Emphasis on Hematological Malignancies and Clinical Translation

MicroRNAs (miRNAs) are evolutionarily conserved small non-coding RNAs, that are involved in the multistep process of carcinogenesis, contributing to all established hallmarks of cancer. In this review, implications of miRNAs in hematological malignancies and their clinical utilization fields are discussed. As components of the complex regulatory network of gene expression, influenced by the tissue microenvironment and epigenetic modifiers, miRNAs are “micromanagers” of all physiological processes including the regulation of hematopoiesis and metabolic pathways. Dysregulated miRNA expression levels contribute to both the initiation and progression of acute leukemias, the metabolic reprogramming of malignantly transformed hematopoietic precursors, and to the development of chemoresistance. Since they are highly stable and can be easily quantified in body fluids and tissue specimens, miRNAs are promising biomarkers for the early detection of hematological malignancies. Besides novel opportunities for differential diagnosis, miRNAs can contribute to advanced chemoresistance prediction and prognostic stratification of acute leukemias. Synthetic oligonucleotides and delivery vehicles aim the therapeutic modulation of miRNA expression levels. However, major challenges such as efficient delivery to specific locations, differences of miRNA expression patterns between pediatric and adult hematological malignancies, and potential side effects of miRNA-based therapies should be considered.