A cochlear progenitor pool influences patterning of the mammalian sensory epithelium via MYBL2.

During embryonic development, Wnt signaling influences both proliferation and sensory formation in the cochlea. How this dual nature of Wnt signaling is coordinated is unknown. In this study, we define a novel role for a Wnt-regulated gene, Mybl2, which was already known to be important for proliferation, in determining the size and patterning of the sensory epithelium in the murine cochlea. Using a quantitative spatial analysis approach and analyzing Mybl2 loss-of-function, we show that Mybl2 promoted proliferation in the inner sulcus domain but limited the size of the sensory domain by influencing their adjoining boundary position via Jag1 regulation during development. Mybl2 loss-of-function simultaneously decreased proliferation in the inner sulcus and increased the size of the sensory domain, resulting in a wider sensory epithelium with ectopic inner hair cell formation during late embryonic stages. These data suggest that progenitor cells in the inner sulcus determine boundary formation and pattern the sensory epithelium via MYBL2.

Transcriptome analysis reveals EBF1 ablation-induced injuries in cardiac system.

Rationale: Regulatory processes of transcription factors (TFs) shape heart development and influence the adult heart's response to stress, contributing to cardiac disorders. Despite their significance, the precise mechanisms underpinning TF-mediated regulation remain elusive. Here, we identify that EBF1, as a TF, is highly expressed in human heart tissues. EBF1 is reported to be associated with human cardiovascular disease, but its roles are unclear in heart. In this study, we investigated EBF1 function in cardiac system. Methods: RNA-seq was utilized to profile EBF1 expression patterns. CRISPR/Cas9 was utilized to knock out EBF1 to investigate its effects. Human pluripotent stem cells (hPSCs) differentiated into cardiac lineages were used to mimic cardiac development. Cardiac function was evaluated on mouse model with Ebf1 knockout by using techniques such as echocardiography. RNA-seq was conducted to analyze transcriptional perturbations. ChIP-seq was employed to elucidate EBF1-bound genes and the underlying regulatory mechanisms. Results: EBF1 was expressed in some human and mouse cardiomyocyte. Knockout of EBF1 inhibited cardiac development. ChIP-seq indicated EBF1's binding on promoters of cardiogenic TFs pivotal to cardiac development, facilitating their transcriptional expression and promoting cardiac development. In mouse, Ebf1 depletion triggered transcriptional perturbations of genes, resulting in cardiac remodeling. Mechanistically, we found that EBF1 directly bound to upstream chromatin regions of cardiac hypertrophy-inducing genes, contributing to cardiac hypertrophy. Conclusions: We uncover the mechanisms underlying EBF1-mediated regulatory processes, shedding light on cardiac development, and the pathogenesis of cardiac remodeling. These findings emphasize EBF1's critical role in orchestrating diverse aspects of cardiac processes and provide a promising therapeutic intervention for cardiomyopathy.

Silencing LINC00663 inhibits inflammation and angiogenesis through downregulation of NR2F1 via EBF1 in bladder cancer.

This study is to elucidate the effect of the LINC00663/EBF1/NR2F1 axis on inflammation and angiogenesis in bladder cancer (BC) and related molecular mechanisms. After transfection, functional experiments were conducted to test cell proliferation and invasion, tube formation ability, and content of inflammatory factors, Snail, E-cadherin, and VEGFA. Meanwhile, the relationships among LINC00663, EBF1, and NR2F1 were predicted and verified. In addition, xenograft experiments in nude mice were performed to observe the oncogenicity of 5637 BC cells in vivo. In BC tissues and cells, LINC00663 and NR2F1 were upregulated. Silencing NR2F1 or LINC00663 repressed cell proliferation and invasion, weakened vascular mimicry in vitro, decreased inflammatory factor, Snail, and VEGFA levels, and increased expression of E-cadherin. LINC00663 positively regulated NR2F1 expression through EBF1. Additionally, in vivo experiments showed that NR2F1 upregulation reversed the suppression effects of LINC00663 silencing on tumour growth, inflammation, and angiogenesis. Silencing LINC00663 decreased NR2F1 expression by mediating EBF1, thereby inhibiting BC inflammation and angiogenesis.

IL-2 delivery to CD8+ T cells during infection requires MRTF/SRF-dependent gene expression and cytoskeletal dynamics.

Paracrine IL-2 signalling drives the CD8 + T cell expansion and differentiation that allow protection against viral infections, but the underlying molecular events are incompletely understood. Here we show that the transcription factor SRF, a master regulator of cytoskeletal gene expression, is required for effective IL-2 signalling during L. monocytogenes infection. Acting cell-autonomously with its actin-regulated cofactors MRTF-A and MRTF-B, SRF is dispensible for initial TCR-mediated CD8+ T cell proliferation, but is required for sustained IL-2 dependent CD8+ effector T cell expansion, and persistence of memory cells. Following TCR activation, Mrtfab-null CD8+ T cells produce IL-2 normally, but homotypic clustering is impaired both in vitro and in vivo. Expression of cytoskeletal structural and regulatory genes, most notably actins, is defective in Mrtfab-null CD8+ T cells. Activation-induced cell clustering in vitro requires F-actin assembly, and Mrtfab-null cell clusters are small, contain less F-actin, and defective in IL-2 retention. Clustering of Mrtfab-null cells can be partially restored by exogenous actin expression. IL-2 mediated CD8+ T cell proliferation during infection thus depends on the control of cytoskeletal dynamics and actin gene expression by MRTF-SRF signalling.

[Effects of inhibition of Rho/ROCK pathway on proliferation and migration of airway smooth muscle cells and related mechanisms]. / 抑制Rho/ROCKé€šè·¯å¯¹æ°”é“å¹³æ»‘è‚Œç»†èƒžå¢žæ®–ä¸Žè¿ç§»çš„å½±å“åŠç›¸å ³æœºåˆ¶.

OBJECTIVES: To investigate the effects and molecular mechanisms of inhibition of the Ras homolog gene (Rho)/Rho-associated coiled-coil forming protein kinase (ROCK) pathway on the proliferation and migration of airway smooth muscle cells involving myocardin (MYOCD). METHODS: Human airway smooth muscle cells were infected with the adenoviral vector Ad-ZsGreen-shRNA-hROCK1 in vitro. The cells were randomly divided into four groups: ROCK1 gene silencing control (shNC) group, shNC + arachidonic acid (AA, Rho/ROCK pathway activator) group, ROCK1 gene silencing (shROCK1) group, and shROCK1 + AA group (n=3 each). Quantitative real-time polymerase chain reaction and Western blot were used to detect the expression levels of ROCK1 and MYOCD mRNA and protein. ELISA was employed to measure the levels of globular actin and filamentous actin, while immunofluorescent staining and scratch assays were utilized to assess cell proliferation and migration. RESULTS: Compared to the shNC + AA group, the shROCK1 + AA group exhibited decreased levels of ROCK1 and MYOCD mRNA and protein expression, reduced expression levels of globular actin and filamentous actin, and diminished cell proliferation and migration capabilities (P<0.05). CONCLUSIONS: Inhibition of the Rho/ROCK pathway suppresses the proliferation and migration of airway smooth muscle cells, which may be associated with the downregulation of MYOCD.

Macrophage MKL1 contributes to cardiac fibrosis in a mouse model of myocardial infarction.

AIMS: Cardiac fibrosis is characterized by aberrant collagen deposition in the heart. Macrophage polarization or infiltration is the main reason to accelerate the collagen deposition. We attempted to investigate the involvement of MKL1 in macrophages during the development of cardiac fibrosis. MATERIALS AND METHODS: Cardiac fibrosis is induced by myocardial infarction (MI). The MKL1f/f mice were crossed to the Lyz2-cre mice to generate macrophage conditional MKL1 knockout mice (MKL1ΔMφ). In addition, macrophage conditional MKL1 overexpression mice (MKL1Mϕ-OE) were constructed by crossing Lyz2-cre mice to MKL1ΔN200-Rosa26 mice. KEY FINDINGS: MKL1 expression was significantly increased in macrophages of both ischemic cardiomyopathy (ICM) patients and mice induced to develop myocardial infarction. Deletion of MKL1 in macrophages improved the heart function after MI-induced cardiac fibrosis. Consistently, MKL1Mϕ-OE mice displayed more severe cardiac fibrosis and worsened heart function than the control mice after MI. Moreover, administration of a small-molecule MKL1 inhibitor CCG-1423 also decreased the collagen deposition after MI. SIGNIFICANCE: Our data demonstrate that MKL1 in macrophages contributes to cardiac fibrosis pathogenesis and reinforce the notion that targeting MKL1 may yield effective antifibrotic therapeutics in the heart.

YjbH contributes to Staphylococcus aureus skin pathology and immune response through Agr-mediated α-toxin regulation.

Staphylococcus aureus is the most common cause of skin and soft tissue infections (SSTIs) with Methicillin-Resistant S. aureus (MRSA) strains being a major contributor in both community and hospital settings. S. aureus relies on metabolic diversity and a large repertoire of virulence factors to cause disease. This includes α-hemolysin (Hla), an integral player in tissue damage found in various models, including SSTIs. Previously, we identified a role for the Spx adapter protein, YjbH, in the regulation of several virulence factors and as an inhibitor of pathogenesis in a sepsis model. In this study, we found that YjbH is critical for tissue damage during SSTI, and its absence leads to decreased proinflammatory chemokines and cytokines in the skin. We identified no contribution of YjbI, encoded on the same transcript as YjbH. Using a combination of reporters and quantitative hemolysis assays, we demonstrated that YjbH impacts Hla expression and activity both in vitro and in vivo. Additionally, expression of Hla from a non-native promoter reversed the tissue damage phenotype of the ΔyjbIH mutant. Lastly, we identified reduced Agr activity as the likely cause for reduced Hla production in the ΔyjbH mutant. This work continues to define the importance of YjbH in the pathogenesis of S. aureus infection as well as identify a new pathway important for Hla production.

Innovative Therapeutic Delivery of Metastasis-Associated in Colon Cancer 1-Suppressing miRNA Using High Transmembrane 4 L6 Family Member 5-Targeting Exosomes in Colorectal Cancer Mouse Models.

Elevated metastasis-associated in colon cancer 1 (MACC1) expression in colorectal cancer patients, and high transmembrane 4 L6 family member 5 (TM4SF5) protein expressed on various solid tumors' surface, are linked to aggressive cancer behavior and progression. In this study, adipose-derived stem cells (ASCs) were engineered to produce exosomes (Ex) that target the TM4SF5 protein on tumors. Moreover, MACC1-targeting microRNA was encapsulated within the Ex, resulting in TM4SF5-targeting Ex (MACC1-suppressing miRNA; miR-143). The anticancer effects of these Ex were investigated in vitro using the human colorectal cell line HCT116 and in vivo using colorectal cancer mouse xenograft models. In the in vivo assessment, administration of TM4SF5-targeting Ex[miR-143], referred to as tEx[miR-143] herein, resulted in the smallest tumor size, the lowest tumor growth rate, and the lightest excised tumors compared to other treatments (p < 0.05). It also led to the decreased expression of MACC-1 and anti-apoptotic markers MCL-1 and Bcl-xL while inducing the highest expression of pro-apoptotic markers BAX and BIM. These results were consistent with in vitro findings, where t Ex[miR-143] demonstrated the highest inhibition of HCT116 cell migration and invasion. These findings highlight the potential of tEx[miR-143] as an effective therapeutic strategy for colorectal cancer, demonstrating promising results in both targetability and anti-tumor effects in vitro and in vivo, warranting further investigation in clinical settings.

From iPSCs to Pancreatic ß Cells: Unveiling Molecular Pathways and Enhancements with Vitamin C and Retinoic Acid in Diabetes Research.

Diabetes mellitus, a chronic and non-transmissible disease, triggers a wide range of micro- and macrovascular complications. The differentiation of pancreatic ß-like cells (PßLCs) from induced pluripotent stem cells (iPSCs) offers a promising avenue for regenerative medicine aimed at treating diabetes. Current differentiation protocols strive to emulate pancreatic embryonic development by utilizing cytokines and small molecules at specific doses to activate and inhibit distinct molecular signaling pathways, directing the differentiation of iPSCs into pancreatic ß cells. Despite significant progress and improved protocols, the full spectrum of molecular signaling pathways governing pancreatic development and the physiological characteristics of the differentiated cells are not yet fully understood. Here, we report a specific combination of cofactors and small molecules that successfully differentiate iPSCs into PßLCs. Our protocol has shown to be effective, with the resulting cells exhibiting key functional properties of pancreatic ß cells, including the expression of crucial molecular markers (pdx1, nkx6.1, ngn3) and the capability to secrete insulin in response to glucose. Furthermore, the addition of vitamin C and retinoic acid in the final stages of differentiation led to the overexpression of specific ß cell genes.

USP26 as a hepatitis B virus-induced deubiquitinase primes hepatocellular carcinogenesis by epigenetic remodeling.

Despite recent advances in systemic therapy for hepatocellular carcinoma (HCC), the prognosis of hepatitis B virus (HBV)-induced HCC patients remains poor. By screening a sgRNA library targeting human deubiquitinases, we find that ubiquitin-specific peptidase 26 (USP26) deficiency impairs HBV-positive HCC cell proliferation. Genetically engineered murine models with Usp26 knockout confirm that Usp26 drives HCC tumorigenesis. Mechanistically, we find that the HBV-encoded protein HBx binds to the promoter and induces the production of USP26, which is an X-linked gene exclusively expressed in the testis. HBx consequently promotes the association of USP26 with SIRT1 to synergistically stabilize SIRT1 by deubiquitination, which promotes cell proliferation and impedes cell apoptosis to accelerate HCC tumorigenesis. In patients with HBV-positive HCC, USP26 is robustly induced, and its levels correlate with SIRT1 levels and poor prognosis. Collectively, our study highlights a causative link between HBV infection, deubiquitinase induction and development of HCC, identifying a druggable target, USP26.

Non-redundant roles for the human mRNA decapping cofactor paralogs DCP1a and DCP1b.

Eukaryotic gene expression is regulated at the transcriptional and post-transcriptional levels, with disruption of regulation contributing significantly to human diseases. The 5' m7G mRNA cap is a central node in post-transcriptional regulation, participating in both mRNA stabilization and translation efficiency. In mammals, DCP1a and DCP1b are paralogous cofactor proteins of the mRNA cap hydrolase DCP2. As lower eukaryotes have a single DCP1 cofactor, the functional advantages gained by this evolutionary divergence remain unclear. We report the first functional dissection of DCP1a and DCP1b, demonstrating that they are non-redundant cofactors of DCP2 with unique roles in decapping complex integrity and specificity. DCP1a is essential for decapping complex assembly and interactions between the decapping complex and mRNA cap-binding proteins. DCP1b is essential for decapping complex interactions with protein degradation and translational machinery. DCP1a and DCP1b impact the turnover of distinct mRNAs. The observation that different ontological groups of mRNA molecules are regulated by DCP1a and DCP1b, along with their non-redundant roles in decapping complex integrity, provides the first evidence that these paralogs have qualitatively distinct functions.

The role of male hormones in bacterial infections: enhancing Staphylococcus aureus virulence through testosterone-induced Agr activation.

Staphylococcus aureus is a notorious pathogen predominantly involved in skin and soft tissue infections, exhibiting a distinct innate sex bias. This study explores the influence of testosterone on the virulence of S. aureus and elucidates its underlying mechanisms. Utilizing a skin abscess model in intact and castrated male mice, we assessed the effects of testosterone on S. aureus pathogenicity. Compared to controls, castrated mice showed significantly reduced abscess sizes and decreased bacterial loads, highlighting the role of testosterone in modulating the severity of S. aureus infections. In vitro experiments revealed that testosterone enhances the hemolytic activity, cytotoxicity, and oxidative stress resistance of S. aureus. Real-time quantitative PCR analysis showed a significant upregulation of the genes encoding α-hemolysin (hla) and phenol-soluble modulin (psmα). Importantly, testosterone treatment significantly enhanced the expression of the accessory gene regulator (Agr) quorum-sensing system components (agrC, agrA, agrB, agrD), while the SaeRS system (saeR, saeS, and sbi) exhibited only slight changes. Gene knockout experiments revealed that deletion of agrC, rather than saeRS and agrBD, abolishes the testosterone-induced enhancement of hemolysis and gene expression, underscoring the key role of AgrC. Molecular docking simulations indicated a direct interaction between testosterone and AgrC protein, with a strong binding affinity at the active site residue SER201. This study provides new insights into the mechanistic basis of how testosterone enhances the pathogenicity of S. aureus, potentially contributing to increased male susceptibility to S. aureus infections and offering a targeted approach for therapeutic interventions.

Transcriptional Profiling of Staphylococcus aureus during the Transition from Asymptomatic Nasal Colonization to Skin Colonization/Infection in Patients with Atopic Dermatitis.

Staphylococcus aureus acts both as a colonizing commensal bacterium and invasive pathogen. Nasal colonization is associated with an increased risk of infection caused by the identical strain. In patients with atopic dermatitis (AD), the degree of S. aureus colonization is associated with the severity of the disease. Here, we comparatively analyzed the in vivo transcriptional profile of S. aureus colonizing the nose and non-diseased skin (non-lesional skin) as opposed to the diseased skin (lesional skin-defined here as infection) of 12 patients with AD. The transcriptional profile during the asymptomatic colonization of the nose closely resembled that of the lesional skin samples for many of the genes studied, with an elevated expression of the genes encoding adhesion-related proteins and proteases. In addition, the genes that modify and remodel the cell wall and encode proteins that facilitate immune evasion showed increased transcriptional activity. Notably, in a subgroup of patients, the global virulence regulator Agr (accessory gene regulator) and downstream target genes were inactive during nasal colonization but upregulated in the lesional and non-lesional skin samples. Taken together, our results demonstrate a colonization-like transcriptional profile on diseased skin and suggest a role for the peptide quorum sensing system Agr during the transition from asymptomatic nasal colonization to skin colonization/infection.

Enhanced Insulin Secretion Through Upregulation of Transcription Factors by Hydroalcoholic Extract of Securigera securidaca Seeds in Diabetic Animal Model.

AIM: In previous studies, the researchers observed an increase in insulin secretion in STZ-treated diabetic rats following treatment with the hydroalcoholic extract of Securigera securidaca (HESS) seeds. This study focuses on the relationship between the antioxidant properties of HESS with changes in diabetic pancreatic tissue and the gene expression of factors that impact insulin secretion. METHODS: In this controlled experimental study, three varying doses of HESS were administered to three groups of diabetic rats induced by STZ. Oxidative stress indicators like total antioxidant capacity (TAC), total oxidant status (TOS) and malondialdehyde were assessed in both pancreatic and liver tissues. Pancreatic histology was studied post-haematoxylin staining. Insulin and FGF21 levels in the blood were measured using the ELISA method. The expression of Nrf2 and FGF21 genes in the pancreas and liver, along with MafA and PDX-1 genes in the pancreas, was quantified using real-time PCR. RESULTS: The administration of HESS in varying doses led to a dose-dependent rise in blood insulin levels and a decrease in blood glucose levels and oxidative stress. By reducing oxidative stress, HESS treatment lowered the heightened levels of NRF2 and FGF21 in the liver and pancreas of diabetic rats, improving pancreatic tissue health. As oxidative stress decreased, the expression of MafA and PDX1 genes in the pancreas approached levels seen in healthy rats. CONCLUSION: HESS elicits an increase in insulin secretion through the mitigation of oxidative stress and tissue damage, as well as the modulation of gene expression related to the insulin transcription factors PDX-1 and MafA.

Computational modeling establishes mechanotransduction as a potent modulator of the mammalian circadian clock.

Mechanotransduction, which is the integration of mechanical signals from the external environment of a cell to changes in intracellular signaling, governs many cellular functions. Recent studies have shown that the mechanical state of the cell is also coupled to the cellular circadian clock. To investigate possible interactions between circadian rhythms and cellular mechanotransduction, we have developed a computational model that integrates the two pathways. We postulated that translocation of the transcriptional regulators MRTF (herein referring to both MRTF-A and MRTF-B), YAP and TAZ (also known as YAP1 and WWTR1, respectively; collectively denoted YAP/TAZ) into the nucleus leads to altered expression of circadian proteins. Simulations from our model predict that lower levels of cytoskeletal activity are associated with longer circadian oscillation periods and higher oscillation amplitudes, which is consistent with recent experimental observations. Furthermore, accumulation of YAP/TAZ and MRTF in the nucleus causes circadian oscillations to decay in our model. These effects hold both at the single-cell level and within a population-level framework. Finally, we investigated the effects of mutations in YAP or lamin A, the latter of which result in a class of diseases known as laminopathies. In silico, oscillations in circadian proteins are substantially weaker in populations of cells with mutations in YAP or lamin A, suggesting that defects in mechanotransduction can disrupt the circadian clock in certain disease states; however, reducing substrate stiffness in the model restores normal oscillatory behavior, suggesting a possible compensatory mechanism. Thus, our study identifies that mechanotransduction could be a potent modulatory cue for cellular clocks and that this crosstalk can be leveraged to rescue the circadian clock in disease states.

SPI1-mediated transcriptional activation of CEP55 promotes the malignant growth of triple-negative breast cancer and M2 macrophage polarization.

BACKGROUND: Triple-negative breast cancer (TNBC) is a subtype of breast cancer that lacks the expression of three receptors commonly targeted in breast cancer treatment. In this study, the research focused on investigating the role of centrosomal protein 55 (CEP55) in TNBC progression and its interaction with the transcription factor Spi-1 proto-oncogene (SPI1). METHODS: Various techniques including qRT-PCR, western blotting, and immunohistochemistry assays were utilized to examine gene expression patterns. Functional assays such as wound-healing assay, transwell invasion assay, 5-Ethynyl-2'-deoxyuridine assay, and metabolic assays were conducted to assess the impact of CEP55 on the behaviors of TNBC cells. CD163-positive macrophages were quantified by flow cytometry. The chromatin immunoprecipitation assay and dual-luciferase reporter assay were performed to assess the association of SPI1 with CEP55. A xenograft mouse model experiment was used to analyze the impact of SPI1 on tumor development in vivo. RESULTS: CEP55 and SPI1 expression levels were significantly upregulated in TNBC tissues and cells. The depletion of CEP55 led to decreased TNBC cell migration, invasion, proliferation, glucose metabolism, and M2 macrophage polarization, indicating its crucial role in promoting TNBC progression. Moreover, SPI1 transcriptionally activated CEP55 in TNBC cells, and its overexpression was associated with accelerated tumor growth in vivo. Further, CEP55 overexpression relieved SPI1 silencing-induced inhibitory effects on TNBC cell migration, invasion, proliferation, glucose metabolism, and M2 macrophage polarization. CONCLUSION: SPI1-mediated transcriptional activation of CEP55 plays a key role in enhancing TNBC cell migration, invasion, proliferation, glucose metabolism, and M2 macrophage polarization. These insights provide valuable information for potential targeted therapies to combat TNBC progression by modulating the SPI1-CEP55 axis.

Overlapping hearing and communication profiles for the deletion and the RAI1 variant form of Smith-Magenis Syndrome (SMS).

Smith-Magenis syndrome (SMS), a rare, genetically linked complex developmental disorder is associated with hearing loss and delays in speech-language development. Approximately 70 % of those with SMS have a genetic deletion within chromosome 17p11.2 and 10 % have a single gene mutation in the same area, known as the RAI1 variant form of SMS. Previous studies presented preliminary comparisons of the phenotype of those with deletion versus the mutation form of SMS, but none focused on hearing, speech-language, and communication profiles. The current study examined patient registry data and compared two groups of individuals with SMS to determine if genetic differences influence the communication phenotype and to determine the importance of the RAI1 gene in hearing, speech, and language abilities in children. Speech-language and hearing data from the international SMS Patient Registry for 33 subjects with SMS were analyzed: 23 with a genetic deletion (SMS (del)) and 10 with an RAI1 mutation (SMS (RAI1)). Hearing status, otopathology findings, early speech-language milestones, mode of communication, intelligibility, vocal quality, language abilities, and literacy skills were analyzed. There were small differences between the groups for hearing status, otopathological findings, mode of communication, voice quality, intelligibility, speech-language abilities, and literacy. Overlap in the speech-language phenotype between groups confirms previous hypotheses that suggest haploinsufficiency of the RAI1 gene is responsible for the SMS phenotype and that the RAI1 gene is critical for speech-language development. Future studies should include direct testing of receptive and expressive language abilities, including analyses of language samples, with larger groups of individuals to replicate and extend the current findings.

MYBL2 Drives Prostate Cancer Plasticity: Inhibiting Its Transcriptional Target CDK2 for RB1-Deficient Neuroendocrine Prostate Cancer.

Phenotypic plasticity is a recognized mechanism driving therapeutic resistance in patients with prostate cancer. Although underlying molecular causations driving phenotypic plasticity have been identified, therapeutic success is yet to be achieved. To identify putative master regulator transcription factors (MR-TF) driving phenotypic plasticity in prostate cancer, this work utilized a multiomic approach using genetically engineered mouse models of prostate cancer combined with patient data to identify MYB proto-oncogene like 2 (MYBL2) as a significantly enriched transcription factor in prostate cancer exhibiting phenotypic plasticity. Genetic inhibition of Mybl2 using independent murine prostate cancer cell lines representing phenotypic plasticity demonstrated Mybl2 loss significantly decreased in vivo growth as well as cell fitness and repressed gene expression signatures involved in pluripotency and stemness. Because MYBL2 is currently not druggable, a MYBL2 gene signature was employed to identify cyclin-dependent kinase-2 (CDK2) as a potential therapeutic target. CDK2 inhibition phenocopied genetic loss of Mybl2 and significantly decreased in vivo tumor growth associated with enrichment of DNA damage. Together, this work demonstrates MYBL2 as an important MR-TF driving phenotypic plasticity in prostate cancer. Furthermore, high MYBL2 activity identifies prostate cancer that would be responsive to CDK2 inhibition. SIGNIFICANCE: Prostate cancers that escape therapy targeting the androgen receptor signaling pathways via phenotypic plasticity are currently untreatable. Our study identifies MYBL2 as a MR-TF in phenotypic plastic prostate cancer and implicates CDK2 inhibition as a novel therapeutic target for this most lethal subtype of prostate cancer.

Hippo pathway effectors YAP, TAZ and TEAD are associated with EMT master regulators ZEB, Snail and with aggressive phenotype in phyllodes breast tumors.

BACKGROUND: Phyllodes tumors (PTs) of the breast are uncommon fibroepithelial neoplasms that tend to recur locally and may have metastatic potential. Their pathogenesis is poorly understood. Hippo signaling pathway plays an essential role in organ size control, tumor suppression, tissue regeneration and stem cell self-renewal. Hippo signaling dysfunction has been implicated in cancer. Recent evidence suggests that there is cross-talk between the Hippo signaling key proteins YAP/TAZ and the epithelial-mesenchymal transition (EMT) master regulators Snail and ZEB. In this study we aimed to investigate the expression of Hippo signaling pathway components and EMT regulators in PTs, in relation to tumor grade. METHODS: Expression of Hippo signaling effector proteins YAP, TAZ and their DNA binding partner TEAD was evaluated by immunohistochemistry in paraffin-embedded tissue specimens from 86 human phyllodes breast tumors (45 benign, 21 borderline, 20 malignant), in comparison with tumor grade and with the expression of EMT-related transcription factors ZEB and Snail. RESULTS: Nuclear immunopositivity for YAP, TAZ and TEAD was detected in both stromal and epithelial cells in PTs and was significantly higher in high grade tumors. Interestingly, there was a significant correlation between the expression of YAP, TAZ, TEAD and the expression of ZEB and SNAIL. CONCLUSIONS: Our results originally implicate Hippo signaling pathway in PTs pathogenesis and suggest that an interaction between Hippo signaling key components and EMT regulators may promote the malignant features of PTs.

ABCC1 Is a ΔNp63 Target Gene Overexpressed in Squamous Cell Carcinoma.

The transcription factor ΔNp63 plays a pivotal role in maintaining the integrity of stratified epithelial tissues by regulating the expression of distinct target genes involved in lineage specification, cell stemness, cell proliferation and differentiation. Here, we identified the ABC transporter subfamily member ABCC1 as a novel ΔNp63 target gene. We found that in immortalized human keratinocytes and in squamous cell carcinoma (SCC) cells, ∆Np63 induces the expression of ABCC1 by physically occupying a p63-binding site (p63 BS) located in the first intron of the ABCC1 gene locus. In cutaneous SCC and during the activation of the keratinocyte differentiation program, ∆Np63 and ABCC1 levels are positively correlated raising the possibility that ABCC1 might be involved in the regulation of the proliferative/differentiative capabilities of squamous tissue. However, we did not find any gross alteration in the structure and morphology of the epidermis in humanized hABCC1 knock-out mice. Conversely, we found that the genetic ablation of ABCC1 led to a marked reduction in inflammation-mediated proliferation of keratinocytes, suggesting that ABCC1 might be involved in the regulation of keratinocyte proliferation upon inflammatory/proliferative signals. In line with these observations, we found a significant increase in ABCC1 expression in squamous cell carcinomas (SCCs), a tumor type characterized by keratinocyte hyper-proliferation and a pro-inflammatory tumor microenvironment. Collectively, these data uncover ABCC1 as an additional ∆Np63 target gene potentially involved in those skin diseases characterized by dysregulation of proliferation/differentiation balance.