YAP/TAZ Signaling and Resistance to Cancer Therapy

Mechanisms of radioresistance and radiosensitization strategies for Triple Negative Breast Cancer

Breast cancer is one of the most common malignant tumors in women. Triple-negative breast cancer (TNBC) is a molecular subtype of breast cancer that is characterized by a high risk of recurrence and poor prognosis. With the increasingly prominent role of radiotherapy in TNBC treatment, patient resistance to radiotherapy is an attractive area of clinical research. Gene expression changes induced by multiple mechanisms can affect the radiosensitivity of TNBC cells to radiotherapy through a variety of ways, and the enhancement of radioresistance is an important factor in the malignant progression of TNBC. The above pathways mainly include DNA damage repair, programmed cell death, cancer stem cells (CSC), antioxidant function, tumor microenvironment, and epithelial-mesenchymal transition (EMT) pathway. Tumor cells can reduce the damage of radiotherapy to themselves through the above ways, resulting in radioresistance. Therefore, in this review, we aim to summarize the strategies for immunotherapy combined with radiotherapy, targeted therapy combined with radiotherapy, and epigenetic therapy combined with radiotherapy to identify the best treatment for TNBC and improve the cure and survival rates of patients with TNBC. This review will provide important guidance and inspiration for the clinical practice of radiotherapy for TNBC, which will help deepen our understanding of this field and promote its development.

Knocking Down Ferredoxin 1 Inhibits the Progression of Colorectal Cancer and Regulates Cuproptosis via Mediating the Hippo Signaling Pathway

Cuproptosis is a form of programmed cell death dependent on mitochondrial respiration and is crucial in cancer treatment. The study attempted to screen cuproptosis-associated genes in colorectal cancer (CRC) and reveal regulatory pathways. Weighted gene co-expression network analysis (WGCNA) was applied to screen the co-expression modules based on gene expression in CRC patients. The cuproptosis-associated genes were screened at the intersection of co-expression modules and cuproptosis gene data set. RNA sequencing was performed to assess the transcriptome changes, followed by functional enrichment analyses to reveal the potential pathways. Ferredoxin 1 (FDX1) was knocked down in in vivo and in vitro experiments to investigate the effects of FDX1 knockdown on CRC progression and cuproptosis. FDX1 was found as a cuproptosis-associated gene and was highly expressed in CRC tumor and CRC cells. Knockdown of FDX1 regulated cuproptosis in CRC cells, and inhibited CRC cell growth, migration and invasion. We screened 1956 upregulated DEGs and 2201 downregulated DEGs in si-FDX1 cells, which were mainly enriched in mitogen-activated protein kinase (MAPK) signaling pathway, tumor necrosis factor (TNF) signaling pathway and Hippo signaling pathway. Knockdown of FDX1 inhibited CRC progression by increasing the levels of dihydrolipoamide S-succinyltransferase (DLST), lipoic acid synthetase (LIAS) and phosphorylation Yes-associated protein (pYAP)/YAP, and downregulated transcriptional coactivator with a PDZ-binding domain (TAZ). The inhibitor of Hippo pathway GA-017 blocked this process. Knocking down FDX1 regulated cuproptosis and inhibited CRC progression by mediating the Hippo signaling pathway, which shed new insights into the development of biomarkers for CRC treatment.

SOX5 inhibition overcomes PARP inhibitor resistance in BRCA-mutated breast and ovarian cancer

Poly (ADP-ribose) polymerase (PARP) inhibitors are effective in cells with homologous recombination (HR) deficiency, including BRCA1/2 mutation. However, PARP inhibitors remain a therapeutic challenge in breast and ovarian cancer due to inevitably acquired resistance in most cases. Therefore, strategies to overcome PARP inhibitor resistance are unmet clinical need. SRY-box transcription factor 5 (SOX5) plays a crucial role in development of various cancers but the role of SOX5 in PARP inhibitor resistance is poorly understood. This study identified SOX5 as a potential biomarker associated with PARP inhibitor resistance and addressed potential treatment strategies to overcome PARP inhibitor resistance using the olaparib-resistant preclinical model. We observed that SOX5 was significantly upregulated in olaparib-resistant cells and contributed to PARP inhibitor resistance by upregulating DNA repair pathway genes. Ectopic SOX5 overexpression contributed to PARP inhibitor resistance by suppressing DNA double-strand breaks (DSBs) in BRCA-mutated breast and ovarian cancer. SOX5 small interfering RNA combined with olaparib sensitized olaparib-resistant cells and suppressed the growth of olaparib-resistant xenografts in mice via increased DSBs represented by ɣH2AX formation. Mechanistically, SOX5 directly interacted with yes-associated protein 1 (YAP1) and promoted its nuclear translocation by suppressing the Hippo pathway. YAP1, in association with TEA domain family members (TEAD), upregulated HR-related gene expression and conferred PARP inhibitor resistance. Furthermore, the clinical relevance of SOX5 as a therapeutic target was supported by a significant association between SOX5 overexpression and poor prognosis in ovarian cancer on public mRNA microarray data sets. Therefore, we propose SOX5 as a promising therapeutic target for overcoming PARP inhibitor resistance in BRCA1/2-mutated breast and ovarian cancer.

It's all downstream from here: RTK/Raf/MEK/ERK pathway resistance mechanisms in glioblastoma

BACKGROUND

The receptor tyrosine kinase (RTK)/Ras/Raf/MEK/ERK signaling pathway is one of the most tumorigenic pathways in cancer, with its hyperactivation strongly linked to the aggressive nature of glioblastoma (GBM). Although extensive research has focused on developing therapeutics targeting this pathway, clinical success remains elusive due to the emergence of resistance mechanisms.

OBJECTIVE

This review investigates how inhibition of the RTK/Ras/Raf/MEK/ERK pathway alters transcription factors, contributing to acquired resistance mechanisms in GBM. It also highlights the critical role of transcription factor dysregulation in therapeutic resistance.

METHODS & RESULTS

Findings from key studies on the RTK/Ras/Raf/MEK/ERK pathway in GBM were synthesized to explore the role of transcription factor dysregulation in resistance to targeted therapies, radiation, and chemotherapy. The review highlights that transcription factors undergo significant dysregulation following RTK/Ras/Raf/MEK/ERK pathway inhibition, contributing to therapeutic resistance.

CONCLUSION

Transcription factors are promising targets for overcoming treatment resistance in GBM, with cotreatment strategies combining RTK/Ras/Raf/MEK/ERK pathway inhibitors and transcription factor-targeted therapies presenting a novel approach. Despite the challenges of targeting complex structures and interactions, advancements in drug development and precision technologies hold great potential. Continued research is essential to refine these strategies and improve outcomes for GBM and other aggressive cancers.

MISP Suppresses Ferroptosis via MST1/2 Kinases to Facilitate YAP Activation in Non-Small Cell Lung Cancer

Despite advances in non-small cell lung cancer (NSCLC) therapies, resistance remains a major challenge. Ferroptosis, a form of regulated cell death, plays a key role in cancer progression and treatment response. However, the mechanisms governing ferroptosis in NSCLC are not fully understood. The Hippo pathway, which regulates cell proliferation, has recently been implicated in ferroptosis regulation. In this study, we identify Mitotic Spindle Positioning (MISP) as a critical inhibitor of ferroptosis in NSCLC. MISP is upregulated in NSCLC tissues, and its loss sensitizes cells to ferroptosis, reducing cell proliferation in vitro and in vivo. Mechanistically, MISP binds to the SARAH domain of MST1/2 kinases, inhibiting their homodimerization and autophosphorylation, leading to sustained activation of YAP, a transcriptional coactivator in the Hippo pathway. YAP activation increases SLC7A11 expression, which protects cells from ferroptosis. We also identify a mutant MISP-R390/391A that disrupts MISP-MST1/2 binding, further illustrating the MST1/2-dependent inhibition of Hippo signaling. Notably, MISP is a target of YAP, creating a feedback loop that amplifies YAP signaling. Our findings suggest a novel MISP-YAP axis regulating ferroptosis, positioning MISP as a potential therapeutic target for NSCLC, especially in cases with dysregulated YAP.

An Agrin-YAP/TAZ Rigidity Sensing Module Drives EGFR-Addicted Lung Tumorigenesis

Despite epidermal growth factor receptor (EGFR) is a pivotal oncogene for several cancers, including lung adenocarcinoma (LUAD), how it senses extracellular matrix (ECM) rigidity remain elusive in the context of the increasing role of tissue rigidity on various hallmarks of cancer development. Here it is shown that EGFR dictates tumorigenic agrin expression in lung cancer cell lines, genetically engineered EGFR-driven mouse models, and human specimens. Agrin expression confers substrate stiffness-dependent oncogenic attributes to EGFR-reliant cancer cells. Mechanistically, agrin mechanoactivates EGFR through epidermal growth factor (EGF)-dependent and independent modes, thereby sensitizing its activity toward localized cancer cell-ECM adherence and bulk rigidity by fostering interactions with integrin β1. Notably, a feed-forward loop linking agrin-EGFR rigidity response to YAP-TEAD mechanosensing is essential for tumorigenesis. Together, the combined inhibition of EGFR-YAP/TEAD may offer a strategy to reduce lung tumorigenesis by disrupting agrin-EGFR mechanotransduction, uncovering a therapeutic vulnerability for EGFR-addicted lung cancers.

Revenge unraveling the fortress: Exploring anticancer drug resistance mechanisms in BC for enhanced therapeutic strategies

Breast cancer (BC) is the most prevalent form of cancer in women worldwide and the main cause of cancer-related fatalities in females. BC can be classified into various types based on where cancer has begun to grow or spread, specific characteristics that influence how cancer behaves, and treatment choices. BC is multifaceted, and due to its diverse nature, the mechanisms involved are complex and have not yet been understood. Overexpression and expression of various factors involved in the functioning of mechanisms lead to abnormal changes, providing an environment supporting cancer cell growth. Understanding BC risk factors and early diagnosis through screening techniques like mammography and diagnostic techniques such as imaging and biopsies has advanced significantly. A wide range of treatment options, including surgery, radiation, chemotherapy, targeted treatments, and hormonal therapies, are now available. Daily advancements are being made in the clinical treatment of BC. Still, BC drug resistance cases remain highly prevalent and are currently one of the biggest problems faced by medical science. To increase response rates and possibly lengthen survival, there is a critical requirement for novel medicines with minimal sensitivity to overcome drug resistance. This review classifies different mechanisms that are involved in the development of BC and workable pharmacological targets and explains how they relate to the development of BC drug resistance. By concentrating on the mechanisms covered in this review, we can have a deep understanding of different mechanisms and learn innovative ways to develop novel therapeutics for the disease to combat medication resistance.

An Overview of Cellular and Molecular Determinants Regulating Chemoresistance in Pleural Mesothelioma

Malignant pleural mesothelioma (PM) is a highly aggressive disease of the lung pleura associated with poor prognosis. Despite advances in improving the clinical management of this malignancy, there is no effective chemotherapy for refractory or relapsing PM. The acquisition of resistance to standard and targeted therapy in this disease is a foremost concern; therefore, a deeper understanding of the complex factors surrounding the emergence of drug resistance is deemed necessary. In this review, we will present broad insights into various cellular and molecular concepts, accounting for the recalcitrance of PM to chemotherapy, including signaling networks regulating drug tolerance, drug resistance-associated proteins, genes, and miRNAs, as well as the critical role of cancer stem cells. Identification of the biological determinants and their associated mechanisms may provide a framework for the development of appropriate treatment.

CLK1 Activates YAP to Promote Intrahepatic Cholangiocarcinogenesis

Cdc2-like kinase 1 (CLK1) has dual-specificity kinase ability to phosphorylate tyrosine and serine/threonine protein residues. CLK1 regulates many physiologic processes and has been shown to contribute to multiple types of cancer. In this study, we investigated the functional role of CLK1 during intrahepatic cholangiocarcinoma (ICC) development. The expression of CLK1 was elevated in ICC tumors, and patients with high expression of CLK1 demonstrated poor prognosis. In hydrodynamically transfected mouse models, CLK1 alone was insufficient to induce ICC, whereas CLK1 cooperated with AKT (AKT/CLK1) to trigger ICC initiation. In addition, overexpression of CLK1 in ICC cells facilitated proliferation in vitro and tumor growth in vivo, whereas loss of CLK1 elicited the opposite effects. Moreover, RNA sequencing analysis indicated that high levels of CLK1 corresponded with activation of the Hippo-Yes-associated protein (YAP) signaling pathway. Consistently, AKT/CLK1 murine tumors displayed upregulation of YAP as well as its downstream targets. Furthermore, loss or pharmacologic inhibition of YAP in ICC cells inhibited CLK1-induced growth, and deletion of Yap completely retarded the induction of AKT/CLK1 tumors. Mechanistically, 4D label-free mass spectrometry and coimmunoprecipitation assays revealed WWC2 as a potential mediator of the CLK1-YAP cascade. Collectively, the current findings identify a critical role for CLK1 in promoting ICC development and indicate that inhibiting YAP might be an effective approach for perturbing CLK1-mediated tumorigenesis. Significance: CLK1 drives intrahepatic cholangiocarcinoma initiation and progression by increasing YAP activity, suggesting that targeting YAP could be a potential strategy for treating and preventing CLK1-driven intrahepatic cholangiocarcinoma.

Gracillin suppresses cancer progression through inducing Merlin/LATS protein-protein interaction and activating Hippo signaling pathway

Gene therapy, epigenetic therapies, natural compounds targeted therapy, photodynamic therapy, nanoparticles, and precision medicines are becoming available to diagnose and treat cancer. Gracillin, a natural steroidal saponin extracted from herbs, has shown potent efficacy against a range of malignancies. In this study, we investigated the molecular anticancer mechanisms of gracillin. We showed that gracillin dose-dependently suppressed proliferation, migration, and invasion in breast cancer, liver cancer, and glioblastoma cells with IC50 values around 1 μM, which were associated with MST-independent activation of Hippo signaling pathway and subsequent decreased YAP activity. We demonstrated that gracillin activated the Hippo signaling by inducing Merlin/LATS protein-protein interaction (PPI). A competitive inhibitory peptide (SP) derived from the binding interface of the PPI, disrupted the interaction, abolishing the anticancer activity of gracillin. In nude mice bearing MDA-MB-231, HCCLM3, or U87MG xenograft tumor, administration of gracillin (5, 10 mg·kg-1·d-1, i.g. for 21 days) dose-dependently suppressed the tumor growth, associated with the induced Merlin/LATS PPI, activated Hippo signaling, as well as decreased YAP activity in tumor tissues. Our data demonstrate that gracillin is an efficacious therapeutic agent for cancer treatment, induction of Merlin/LATS PPI might provide proof-of-concept in developing therapeutic agent for cancer treatment.

The Hippo pathway: Organ size control and beyond

The Hippo signaling pathway is a highly conserved signaling network for controlling organ size, tissue homeostasis, and regeneration. It integrates a wide range of intracellular and extracellular signals, such as cellular energy status, cell density, hormonal signals, and mechanical cues, to modulate the activity of YAP/TAZ transcriptional coactivators. A key aspect of Hippo pathway regulation involves its spatial organization at the plasma membrane, where upstream regulators localize to specific membrane subdomains to regulate the assembly and activation of the pathway components. This spatial organization is critical for the precise control of Hippo signaling, as it dictates the dynamic interactions between pathway components and their regulators. Recent studies have also uncovered the role of biomolecular condensation in regulating Hippo signaling, adding complexity to its control mechanisms. Dysregulation of the Hippo pathway is implicated in various pathological conditions, particularly cancer, where alterations in YAP/TAZ activity contribute to tumorigenesis and drug resistance. Therapeutic strategies targeting the Hippo pathway have shown promise in both cancer treatment, by inhibiting YAP/TAZ signaling, and regenerative medicine, by enhancing YAP/TAZ activity to promote tissue repair. The development of small molecule inhibitors targeting the YAP-TEAD interaction and other upstream regulators offers new avenues for therapeutic intervention. SIGNIFICANCE STATEMENT: The Hippo signaling pathway is a key regulator of organ size, tissue homeostasis, and regeneration, with its dysregulation linked to diseases such as cancer. Understanding this pathway opens new possibilities for therapeutic approaches in regenerative medicine and oncology, with the potential to translate basic research into improved clinical outcomes.

Pharmacological Dissection Identifies Retatrutide Overcomes the Therapeutic Barrier of Obese TNBC Treatments through Suppressing the Interplay between Glycosylation and Ubiquitylation of YAP

Triple-negative breast cancer (TNBC) in obese patients remains challenging. Recent studies have linked obesity to an increased risk of TNBC and malignancies. Through multiomic analysis and experimental validation, a dysfunctional Eukaryotic Translation Initiation Factor 3 Subunit H (EIF3H)/Yes-associated protein (YAP) proteolytic axis is identified as a pivotal junction mediating the interplay between cancer-associated adipocytes and the response to anti-cancer drugs in TNBC. Mechanistically, cancer-associated adipocytes drive metabolic reprogramming resulting in an upregulated hexosamine biosynthetic pathway (HBP). This aberrant upregulation of HBP promotes YAP O-GlcNAcylation and the subsequent recruitment of EIF3H deubiquitinase, which stabilizes YAP, thus promoting tumor growth and chemotherapy resistance. It is found that Retatrutide, an anti-obesity agent, inhibits HBP and YAP O-GlcNAcylation leading to increased YAP degradation through the deprivation of EIF3H-mediated deubiquitylation of YAP. In preclinical models of obese TNBC, Retatrutide downregulates HBP, decreases YAP protein levels, and consequently decreases tumor size and enhances chemotherapy efficacy. This effect is particularly pronounced in obese mice bearing TNBC tumors. Overall, these findings reveal a critical interplay between adipocyte-mediated metabolic reprogramming and EIF3H-mediated YAP proteolytic control, offering promising therapeutic strategies to mitigate the adverse effects of obesity on TNBC progression.

WISP1 inhibition of YAP phosphorylation drives breast cancer growth and chemoresistance via TEAD4 activation

Wnt1-inducible signaling pathway protein 1 (WISP1) promotes breast cancer. The Hippo signaling pathway demonstrates a potential connection with WISP1, necessitating an exploration of their interaction. This study hypothesized that WISP1 boosts breast cancer by modulating the Hippo signaling pathway. The Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) databases were used to analyze WISP1 expression and Hippo signaling in breast cancer patients. WISP1, yes-associated protein (YAP), and domain family member 4 (TEAD4) were overexpressed or silenced in breast cancer cells. Epithelial-mesenchymal transition (EMT), and chemoresistance of breast cancer cells were evaluated. Immunofluorescence, PCR, immunoprecipitation, and western blot were used to detect the expression of WISP1 and key Hippo signaling factors and their interactions. Enrichment analysis indicated activation of WISP1 and Hippo signaling pathway and correlated with a worse prognosis in breast cancer. WISP1 overexpression facilitated EMT and chemotherapy resistance in breast cancer. Importantly, overexpression of WISP1 promoted YAP's nuclear translocation. TEAD4 expression in YAP precipitates from nuclear of WISP1-overexpressing MCF-7 cells increased. The promoting effect of WISP1 on breast cancer was counteracted by silencing YAP or TEAD4. Moreover, in WISP1 small interfering RNA-transfected MCF-7 cells, p-YAP expression increased, while interaction between YAP and TEAD4 decreased. WISP1 silencing led to ubiquitin increase and TEAD reduction in the p-YAP precipitates. In conclusion, WISP1 promotes YAP nuclear translocation and binding with TEAD4 by inhibiting YAP phosphorylation, reducing ubiquitin recruitment, and participating in transcriptional regulation in breast cancer.

YAP acts as an independent prognostic marker and regulates growth and metastasis of gastrointestinal stromal tumors via FBXW7-YAP pathway

BACKGROUND

Although imatinib (IM) and subsequent tyrosine kinase inhibitors (TKIs) significantly improve the prognosis of GIST patients by delaying metastasis and recurrence, most patients experience limited efficacy due to toxicity and secondary resistance. We evaluated Yes-associated protein (YAP), a coactivator of the Hippo pathway accounting for IM resistance and aggressive GIST phenotypes, in GISTs. The degradation of YAP is mediated by FBXW7, and FBXW7 predicts recurrence and IM efficacy for GIST patients. Here, we aimed to identify the potential of YAP as a prognostic marker for patients with GISTs, and the molecular mechanism of FBXW7-YAP pathway in GIST cells.

METHODS

We measured YAP expression in 167 GIST cases using immunohistochemical staining, correlated its expression levels with clinicopathological features, and the molecular mechanism underlying the FBXW7-YAP pathway was further examined in vitro and in vivo.

RESULTS

Compared to 80 (47.9%) cases in the low YAP expression group, 87 (52.1%) cases with high YAP expression associated with a poorer prognosis in terms of overall survival (P = 0.004) and recurrence-free survival (P = 0.003). YAP expression was identified as a significant independent factor affecting the 5-year overall survival (P = 0.005) and recurrence-free survival rates (P = 0.007). Moreover, YAP was directly targeted by FBXW7 to affect proliferation, invasion, and migration in GIST cells. High YAP expression correlated with FBXW7 deficiency, as shown in xenograft and metastasis mouse models.

CONCLUSIONS

YAP expression serves as a predictive marker of recurrence for GIST patients with curative resection, highlighting its potential as a novel therapeutic target that warrants further investigation.

Molecular mechanisms of Hippo pathway in tumorigenesis: therapeutic implications

The Hippo signaling pathway is a pivotal regulator of tissue homeostasis, organ size, and cell proliferation. Its dysregulation is profoundly implicated in various forms of cancer, making it a highly promising target for therapeutic intervention. This review extensively evaluates the mechanisms underlying the dysregulation of the Hippo pathway in cancer cells and the molecular processes linking these alterations to tumorigenesis. Under normal physiological conditions, the Hippo pathway is a guardian, ensuring controlled cellular proliferation and programmed cell death. However, numerous mutations and epigenetic modifications can disrupt this equilibrium in cancer cells, leading to unchecked cell proliferation, enhanced survival, and metastatic capabilities. The pathway's interaction with other critical signaling networks, including Wnt/β-catenin, PI3K/Akt, TGF-β/SMAD, and EGFR pathways, further amplifies its oncogenic potential. Central to these disruptions is the activation of YAP and TAZ transcriptional coactivators, which drive the expression of genes that promote oncogenesis. This review delves into the molecular mechanisms responsible for the dysregulation of the Hippo pathway in cancer, elucidating how these disruptions contribute to tumorigenesis. We also explore potential therapeutic strategies, including inhibitors targeting YAP/TAZ activity and modulators of upstream signaling components. Despite significant advancements in understanding the Hippo pathway's role in cancer, numerous questions remain unresolved. Continued research is imperative to unravel the complex interactions within this pathway and to develop innovative and effective therapies for clinical application. In conclusion, the comprehensive understanding of the Hippo pathway's regulatory mechanisms offers significant potential for advancing cancer therapies, regenerative medicine, and treatments for chronic diseases. The translation of these insights into clinical practice will necessitate collaborative efforts from researchers, clinicians, and pharmaceutical developers to bring novel and effective therapies to patients, ultimately improving clinical outcomes and advancing the field of oncology.

Cooperation between the Hippo and MAPK pathway activation drives acquired resistance to TEAD inhibition

TEAD (transcriptional enhanced associate domain) transcription factors (TEAD1-4) serve as the primary effectors of the Hippo signaling pathway in various cancers. Targeted therapy leads to the emergence of resistance and the underlying mechanism of resistance to TEAD inhibition in cancers is less characterized. We uncover that upregulation of the AP-1 (activator protein-1) transcription factors, along with restored YAP (yes-associated protein) and TEAD activity, drives resistance to GNE-7883, a pan-TEAD inhibitor. Acute GNE-7883 treatment abrogates YAP-TEAD binding and attenuates FOSL1 (FOS like 1) activity. TEAD inhibitor resistant cells restore YAP and TEAD chromatin occupancy, acquire additional FOSL1 binding and exhibit increased MAPK (mitogen-activated protein kinase) pathway activity. FOSL1 is required for the chromatin binding of YAP and TEAD. This study describes a clinically relevant interplay between the Hippo and MAPK pathway and highlights the key role of MAPK pathway inhibitors in mitigating resistance to TEAD inhibition in Hippo pathway dependent cancers.

Decoding gene expression profiles of Hippo signaling pathway components in breast cancer

INTRODUCTION

The Hippo signaling pathway is an evolutionarily conserved, tumor suppressor, stem cell pathway. This is the very less explored pathway in Breast Cancer. It is a crucial regulator of several biological processes, such as organ size, differentiation, tissue homeostasis, cellular proliferation, and stemness. Interestingly, deregulation of this pathway leads to tumorigenesis. Hence, the present study aims to identify the role of the Hippo signaling pathway in Breast Cancer.

MATERIALS AND METHODS

The mRNA expression of the Hippo signaling pathway molecules was evaluated in 120 pre-therapeutic patients by quantitative real-time PCR. Statistical analysis was carried out using SPSS 23. The association between the gene expression and clinicopathological parameters was analyzed by the paired sample t-test, and Pearson chi-square test. ROC curve analysis was carried out using Med Cal. A p-value of ≤ 0.05 was considered statistically significant.

RESULTS

The hippo signaling pathway contains 10 core components i.e.SAV1, MOB1A, MOB1B, MST1, MST2, LATS1, LATS2, YAP, TAZ, and TEAD1 which were downregulated in malignant tissues as compared to adjacent normal tissue in breast cancer. In the correlation of hippo signaling pathway molecules with clinico pathological parameters, only LATS1, MST1, and SAV1 were found to be significantly negatively associated with stages of Breast Cancer. MOB1B was found to be significantly positively correlated with stages of Breast Cancer. ROC curve analysis of YAP, TAZ, LATS2, and TEAD showed significant discrimination between adjacent normal and malignant tissue.

CONCLUSION

In the current study, all the molecules of the hippo signaling pathway i.e. YAP, TAZ, LATS1, LATS2, MST1, MST2, SAV1, MOB1, MOB1B, TEAD1 were downregulated in BC suggesting the activation of hippo pathway which played a significant role in tumor suppression.

The Hippo pathway promotes platinum-based chemotherapy by inhibiting MTF1-dependent heavy metal response

The platinum-based compounds are widely used in treating various types of cancer through their heavy metal component platinum. However, the development of chemoresistance often limits their clinical effectiveness. In this study, we report the roles of heavy metal response and its associated Hippo pathway in regulating platinum-based chemotherapy. Our data show that the MTF1-dependent heavy metal response induces cancer cell resistance to platinum-based compounds both in vitro and in vivo. This resistance is mitigated by Hippo pathway-mediated phosphorylation of MTF1. Moreover, pharmacological activation of the Hippo pathway sensitizes cancer cells to platinum-based compounds. Clinically, lung adenocarcinoma (LUAD) patients with high MTF1 activity exhibit poor overall survival rates, and Hippo pathway inactivation is positively correlated with elevated MTF1 transcriptional activity in platinum-treated LUAD patients. Collectively, our findings not only unveil a critical role of the Hippo-MTF1 pathway in regulating the response to platinum-based chemotherapy, but also suggest new strategies to enhance its efficacy by targeting the heavy metal response.

Dimethyl fumarate promotes the degradation of HNF1B and suppresses the progression of clear cell renal cell carcinoma

Clear cell renal cell carcinoma (ccRCC) is the most lethal subtype of renal cancer, and its treatment options remain limited. Therefore, there is an urgent need to discover therapeutic agents for ccRCC treatment. Here, we demonstrate that dimethyl fumarate (DMF), an approved medication for multiple sclerosis [1] and psoriasis, can inhibit the proliferation of ccRCC cells. Mechanistically, hepatocyte nuclear factor 1β (HNF1B), a transcription factor highly expressed in ccRCC, is succinated by DMF at cysteine residues, leading to its proteasomal degradation. Furthermore, HNF1B interacts with and stabilizes Yes-associated protein (YAP), thus DMF-mediated HNF1B degradation decreases YAP protein level and the expression of its target genes, resulting in the suppression of ccRCC cell proliferation. Importantly, oral administration of DMF sensitizes ccRCC to sunitinib treatment and enhances its efficacy in mice. In summary, we provide evidences supporting DMF as a potential drug for clinical treatment of ccRCC by targeting HNF1B and reveal a previously unrecognized role of HNF1B in regulating YAP in ccRCC.

TNBC response to paclitaxel phenocopies interferon response which reveals cell cycle-associated resistance mechanisms

Paclitaxel is a standard of care neoadjuvant therapy for patients with triple negative breast cancer (TNBC); however, it shows limited benefit for locally advanced or metastatic disease. Here we used a coordinated experimental-computational approach to explore the influence of paclitaxel on the cellular and molecular responses of TNBC cells. We found that escalating doses of paclitaxel resulted in multinucleation, promotion of senescence, and initiation of DNA damage induced apoptosis. Single-cell RNA sequencing (scRNA-seq) of TNBC cells after paclitaxel treatment revealed upregulation of innate immune programs canonically associated with interferon response and downregulation of cell cycle progression programs. Systematic exploration of transcriptional responses to paclitaxel and cancer-associated microenvironmental factors revealed common gene programs induced by paclitaxel, IFNB, and IFNG. Transcription factor (TF) enrichment analysis identified 13 TFs that were both enriched based on activity of downstream targets and also significantly upregulated after paclitaxel treatment. Functional assessment with siRNA knockdown confirmed that the TFs FOSL1, NFE2L2 and ELF3 mediate cellular proliferation and also regulate nuclear structure. We further explored the influence of these TFs on paclitaxel-induced cell cycle behavior via live cell imaging, which revealed altered progression rates through G1, S/G2 and M phases. We found that ELF3 knockdown synergized with paclitaxel treatment to lock cells in a G1 state and prevent cell cycle progression. Analysis of publicly available breast cancer patient data showed that high ELF3 expression was associated with poor prognosis and enrichment in programs associated with cell cycle progression. Together these analyses disentangle the diverse aspects of paclitaxel response and identify ELF3 upregulation as a putative biomarker of paclitaxel resistance in TNBC.

YAP/TEAD4/SP1-induced VISTA expression as a tumor cell-intrinsic mechanism of immunosuppression in colorectal cancer

Hyperactivation of the YAP/TEAD transcriptional complex in cancers facilitates the development of an immunosuppressive tumor microenvironment. Herein, we observed that the transcription factor SP1 physically interacts with and stabilizes the YAP/TEAD complex at regulatory genomic loci in colorectal cancer (CRC). In response to serum stimulation, PKCζ (protein kinase C ζ) was found to phosphorylate SP1 and enhance its interaction with TEAD4. As a result, SP1 enhanced the transcriptional activity of YAP/TEAD and coregulated the expression of a group of YAP/TEAD target genes. The immune checkpoint V-domain Ig suppressor of T-cell activation (VISTA) was identified as a direct target of the SP1-YAP/TEAD4 complex and found to be widely expressed in CRC cells. Importantly, YAP-induced VISTA upregulation in human CRC cells was found to strongly suppress the antitumor function of CD8+ T cells. Consistently, elevated VISTA expression was found to be correlated with hyperactivation of the SP1-YAP/TEAD axis and associated with poor prognosis of CRC patients. In addition, we found by serendipity that enzymatic deglycosylation significantly improved the anti-VISTA antibody signal intensity, resulting in more accurate detection of VISTA in clinical tumor samples. Overall, our study identified SP1 as a positive modulator of YAP/TEAD for the transcriptional regulation of VISTA and developed a protein deglycosylation strategy to better detect VISTA expression in clinical samples. These findings revealed a new tumor cell-intrinsic mechanism of YAP/TAZ-mediated cancer immune evasion.

Cell confinement by micropatterning induces phenotypic changes in cancer-associated fibroblasts

Recent advances in single-cell studies have revealed the vast transcriptomic heterogeneity of cancer-associated fibroblasts (CAFs), with each subset likely having unique roles in the tumor microenvironment. However, it is still unclear how different CAF subsets should be cultured in vitro to recapitulate their in vivo phenotype. The inherent plasticity of CAFs, or their ability to dynamically change their phenotype in response to different environmental stimuli, makes it highly challenging to induce and maintain a specific CAF state in vitro. In this study, we investigated how cell shape and confinement on two-dimensional culture substrates with different stiffnesses influence CAF transcriptomic profile and phenotype. Using micropatterning of polyacrylamide hydrogels to induce shape- and confinement-dependent changes in cell morphology, we observed that micropatterned CAFs exhibited phenotypic shifts towards more desmoplastic and inflammatory CAF subsets. Additionally, micropatterning enabled control over a range of CAF-specific markers and pathways. Lastly, we report how micropatterned and non-micropatterned CAFs respond differently to anti-cancer drugs, highlighting the importance of phenotype-oriented therapy that considers for CAF plasticity and regulatory networks. Control over CAF morphology offers a unique opportunity to establish highly robust CAF phenotypes in vitro, facilitating deeper understanding of CAF plasticity, heterogeneity, and development of novel therapeutic targets. STATEMENT OF SIGNIFICANCE: Cancer-associated fibroblasts (CAFs) are the dominant stromal cell type in many cancers, and recent studies have revealed that they are highly heterogeneous and comprise several subpopulations. It is still unclear how different subsets of CAFs should be cultured in vitro to recapitulate their in vivo phenotype. In this study, we investigated how cell shape and confinement affect CAF transcriptomic profile and phenotype. We report that micropatterned CAFs resemble desmoplastic and inflammatory CAF subsets observed in vivo and respond differently to anti-cancer drugs as compared to non-patterned CAFs. Control over CAF morphology enables the generation of highly robust CAF phenotypes in vitro, facilitating deeper understanding of CAF plasticity and heterogeneity.

Positive feedback between arginine methylation of YAP and methionine transporter SLC43A2 drives anticancer drug resistance

Yes-associated protein (YAP) activation confers resistance to chemotherapy and targeted therapy. Methionine participates in cellular processes by converting to methyl donor for the methylation of DNA, RNA and protein. However, it remains unclear whether methionine affects drug resistance by influencing YAP activity. In this study, we report that methionine deprivation remarkably suppresses the transcriptional activity of YAP-TEAD in cancer cells. Methionine promotes PRMT1-catalyzed asymmetric dimethylation at R124 of YAP (YAP R124me2a). Mimicking of YAP methylation abolishes the reduction effect of methionine-restricted diet on YAP-induced drug resistance. YAP activates the transcription of SLC43A2, the methionine transporter, to increase methionine uptake in cancer cells. Knockdown of SLC43A2 decreases the level of YAP R124me2a. BCH, the inhibitor of SLC43A2, sensitizes tumors to anticancer drugs. Thus, our results unravel the positive feedback between YAP R124 methylation and SLC43A2 that contributes to anticancer drug resistance. Disrupting this positive feedback could be a potential strategy for cancer therapy.

Advances in research on the carcinogenic mechanisms and therapeutic potential of YAP1 in bladder cancer (Review)

Bladder cancer is the most common malignant tumor of the urinary system with high morbidity and no clear pathogenesis. The Hippo signaling pathway is an evolutionarily conserved pathway that regulates organ size and maintains tissue homeostasis. Yes‑associated protein 1 (YAP1) is a key effector of this pathway and regulates downstream target genes by binding to transcriptional co‑activators with PDZ binding sequences (TAZ). Several studies have demonstrated that YAP1 is overexpressed in bladder cancer and is involved in adverse outcomes such as bladder cancer occurrence, progression, resistance to cisplatin and the recurrence of tumours. The present review summarized the involvement of YAP1 in bladder cancer disease onset and progression, and the mechanism of YAP1 involvement in bladder cancer treatment. In addition, this study further explored the potential of YAP1 in the diagnosis and treatment of bladder cancer. This study aimed to explore the potential mechanism of YAP1 in the treatment of bladder cancer.

The Prognostic Impact of SIRT1, STAT3, and YAP1 in Colorectal Carcinoma

Colorectal cancer (CRC) is the most common gastrointestinal malignancy with a complicated behavior including relapse, metastasis, and development of resistance to chemotherapeutic drugs. Silent information regulator 2 homologue 1 (SIRT1), signal transducer and activator of transcription 3 (STAT3), and yes-associated protein (YAP) are cancer-related genes that have unclarified actions and even controversial roles in many human cancers including CRC. The current study aimed to evaluate the prognostic roles of SIRT1, STAT3, and YAP in CRC. Hundred and 13 CRC archival blocks were processed by TMA technique and immunostained with SIRT1, STAT3, and YAP antibodies. SIRT1, STAT3, and YAP are expressed in both tumor and stromal cells. SIRT1 expression in both the epithelial and stromal compartments was associated with favorable prognostic parameters, including longer overall and recurrence-free survival. In contrast, the epithelial and stromal expression of both STAT3 and YAP1 was associated with poor prognostic parameters, including short overall and recurrence-free survival. STAT3 and YAP epithelial expression showed a positive correlation with one another, but a negative correlation with epithelial SIRT1. While SIRT1 stromal expression was inversely correlated with stromal YAP expression, STAT3 and YAP concurrent stromal expression demonstrated a positive correlation with one another. There is crosstalk between CRC tumor and stromal cells by the coparallel expression of molecules such as SIRT1, STAT3, and YAP. There is a synergism between the STAT3 and YAP pathways in CRC at the level of the tumor and stroma. The tumor microenvironment of CRC could modulate tumor behavior by expressing markers suppressing invasion, such as SIRT1 or enhancing invasion, such as STAT3 and YAP.

Targeting Fibrosis: From Molecular Mechanisms to Advanced Therapies

As the final stage of disease-related tissue injury and repair, fibrosis is characterized by excessive accumulation of the extracellular matrix. Unrestricted accumulation of stromal cells and matrix during fibrosis impairs the structure and function of organs, ultimately leading to organ failure. The major etiology of fibrosis is an injury caused by genetic heterogeneity, trauma, virus infection, alcohol, mechanical stimuli, and drug. Persistent abnormal activation of "quiescent" fibroblasts that interact with or do not interact with the immune system via complicated signaling cascades, in which parenchymal cells are also triggered, is identified as the main mechanism involved in the initiation and progression of fibrosis. Although the mechanisms of fibrosis are still largely unknown, multiple therapeutic strategies targeting identified molecular mechanisms have greatly attenuated fibrotic lesions in clinical trials. In this review, the organ-specific molecular mechanisms of fibrosis is systematically summarized, including cardiac fibrosis, hepatic fibrosis, renal fibrosis, and pulmonary fibrosis. Some important signaling pathways associated with fibrosis are also introduced. Finally, the current antifibrotic strategies based on therapeutic targets and clinical trials are discussed. A comprehensive interpretation of the current mechanisms and therapeutic strategies targeting fibrosis will provide the fundamental theoretical basis not only for fibrosis but also for the development of antifibrotic therapies.

Unraveling the Role of the Tumor Extracellular Matrix to Inform Nanoparticle Design for Nanomedicine

The extracellular matrix (ECM)-and its mechanobiology-regulates key cellular functions that drive tumor growth and development. Accordingly, mechanotherapy is emerging as an effective approach to treat fibrotic diseases such as cancer. Through restoring the ECM to healthy-like conditions, this treatment aims to improve tissue perfusion, facilitating the delivery of chemotherapies. In particular, the manipulation of ECM is gaining interest as a valuable strategy for developing innovative treatments based on nanoparticles (NPs). However, further progress is required; for instance, it is known that the presence of a dense ECM, which hampers the penetration of NPs, primarily impacts the efficacy of nanomedicines. Furthermore, most 2D in vitro studies fail to recapitulate the physiological deposition of matrix components. To address these issues, a comprehensive understanding of the interactions between the ECM and NPs is needed. This review focuses on the main features of the ECM and its complex interplay with NPs. Recent advances in mechanotherapy are discussed and insights are offered into how its combination with nanomedicine can help improve nanomaterials design and advance their clinical translation.

Targeting the Hippo pathway in cancer: kidney toxicity as a class effect of TEAD inhibitors?

The Hippo pathway has emerged as a critical player in both cancers and targeted therapy resistance. Recent drug discovery efforts have led to the development of TEAD inhibitors, several of which have already progressed to the clinic. To truly leverage their potential as anticancer therapeutics, safety considerations, particularly in regard to the kidney, warrant additional investigation. This review explores the Hippo pathway's role in cancers, its therapeutic potential, role in kidney development, and the need to evaluate the best strategies to translate its clinical application for long-term patient benefit.

YAP/TEAD involvement in resistance to paclitaxel chemotherapy in lung cancer

The Yes-associated protein (YAP) oncoprotein has been linked to both metastases and resistance to targeted therapy of lung cancer cells. We aimed to investigate the effect of YAP pharmacological inhibition, using YAP/TEA domain (TEAD) transcription factor interaction inhibitors in chemo-resistant lung cancer cells. YAP subcellular localization, as a readout for YAP activation, cell migration, and TEAD transcription factor functional transcriptional activity were investigated in cancer cell lines with up-regulated YAP, with and without YAP/TEAD interaction inhibitors. Parental (A549) and paclitaxel-resistant (A549R) cell transcriptomes were analyzed. The half-maximal inhibitory concentration (IC50) of paclitaxel or trametinib, which are Mitogen-Activated protein kinase and Erk Kinase (MEK) inhibitors, combined with a YAP/TEAD inhibitor (IV#6), was determined. A three-dimensional (3D) microfluidic culture device enabled us to study the effect of IV#6/paclitaxel combination on cancer cells isolated from fresh resected lung cancer samples. YAP activity was significantly higher in paclitaxel-resistant cell lines. The YAP/TEAD inhibitor induced a decreased YAP activity in A549, PC9, and H2052 cells, with reduced YAP nuclear staining. Wound healing assays upon YAP inhibition revealed impaired cell motility of lung cancer A549 and mesothelioma H2052 cells. Combining YAP pharmacological inhibition with trametinib in K-Ras mutated A549 cells recapitulated synthetic lethality, thereby sensitizing these cells to MEK inhibition. The YAP/TEAD inhibitor lowered the IC50 of paclitaxel in A549R cells. Differential transcriptomic analysis of parental and A549R cells revealed an increased YAP/TEAD transcriptomic signature in resistant cells, downregulated upon YAP inhibition. The YAP/TEAD inhibitor restored paclitaxel sensitivity of A549R cells cultured in a 3D microfluidic system, with lung cancer cells from a fresh tumor efficiently killed by YAP/TEAD inhibitor/paclitaxel doublet. Evidence of the YAP/TEAD transcriptional program's role in chemotherapy resistance paves the way for YAP therapeutic targeting.

YAP/TAZ mediates resistance to KRAS inhibitors through inhibiting proapoptosis and activating the SLC7A5/mTOR axis

KRAS mutations are frequent in various human cancers. The development of selective inhibitors targeting KRAS mutations has opened a new era for targeted therapy. However, intrinsic and acquired resistance to these inhibitors remains a major challenge. Here, we found that cancer cells resistant to KRAS G12C inhibitors also display cross-resistance to other targeted therapies, such as inhibitors of RTKs or SHP2. Transcriptomic analyses revealed that the Hippo-YAP/TAZ pathway is activated in intrinsically resistant and acquired-resistance cells. Constitutive activation of YAP/TAZ conferred resistance to KRAS G12C inhibitors, while knockdown of YAP/TAZ or TEADs sensitized resistant cells to these inhibitors. This scenario was also observed in KRAS G12D-mutant cancer cells. Mechanistically, YAP/TAZ protects cells from KRAS inhibitor-induced apoptosis by downregulating the expression of proapoptotic genes such as BMF, BCL2L11, and PUMA, and YAP/TAZ reverses KRAS inhibitor-induced proliferation retardation by activating the SLC7A5/mTORC1 axis. We further demonstrated that dasatinib and MYF-03-176 notably enhance the efficacy of KRAS inhibitors by reducing SRC kinase activity and TEAD activity. Overall, targeting the Hippo-YAP/TAZ pathway has the potential to overcome resistance to KRAS inhibitors.

Advances towards potential cancer therapeutics targeting Hippo signaling

Decades of research into the Hippo signaling pathway have greatly advanced our understanding of its roles in organ growth, tissue regeneration, and tumorigenesis. The Hippo pathway is frequently dysregulated in human cancers and is recognized as a prominent cancer signaling pathway. Hence, the Hippo pathway represents an ideal molecular target for cancer therapies. This review will highlight recent advancements in targeting the Hippo pathway for cancer treatment and discuss the potential opportunities for developing new therapeutic modalities.

Induction of the TEAD Coactivator VGLL1 by Estrogen Receptor-Targeted Therapy Drives Resistance in Breast Cancer

Resistance to endocrine therapies (ET) is common in estrogen receptor (ER)-positive breast cancer, and most relapsed patients die with ET-resistant disease. Although genetic mutations provide explanations for some relapses, mechanisms of resistance remain undefined in many cases. Drug-induced epigenetic reprogramming has been shown to provide possible routes to resistance. By analyzing histone H3 lysine 27 acetylation profiles and transcriptional reprogramming in models of ET resistance, we discovered that selective ER degraders, such as fulvestrant, promote expression of vestigial-like 1 (VGLL1), a coactivator for TEF-1 and AbaA domain (TEAD) transcription factors. VGLL1, acting via TEADs, promoted the expression of genes that drive the growth of fulvestrant-resistant breast cancer cells. Pharmacological disruption of VGLL1-TEAD4 interaction inhibited VGLL1/TEAD-induced transcriptional programs to prevent the growth of resistant cells. EGFR was among the VGLL1/TEAD-regulated genes, and VGLL1-directed EGFR upregulation sensitized fulvestrant-resistant breast cancer cells to EGFR inhibitors. Taken together, these findings identify VGLL1 as a transcriptional driver in ET resistance and advance therapeutic possibilities for relapsed ER+ breast cancer patients. Significance: Transcriptional reprogramming mediated by the upregulation of the TEAD coactivator VGLL1 confers resistance to estrogen receptor degraders in breast cancer but provides alternative therapeutic options for this clinically important patient group.

Mechano-assisted strategies to improve cancer chemotherapy

Chemotherapy remains a cornerstone in cancer treatment; however, its effectiveness is frequently undermined by the development of drug resistance. Recent studies underscores the pivotal role of the tumor mechanical microenvironment (TMME) and the emerging field of mechanical nanomedicine in tackling chemo-resistance. This review offers an in-depth analysis of mechano-assisted strategies aimed at mitigating chemo-resistance through the modification of the TMME and the refinement of mechanical nanomedicine delivery systems. We explore the potential of targeting abnormal tumor mechanical properties as a promising avenue for enhancing the efficacy of cancer chemotherapy, which offers novel directions for advancing future cancer therapies, especially from the mechanomedicine perspective.

The potential role of HPV oncoproteins in the PD-L1/PD-1 pathway in cervical cancer: new perspectives on cervical cancer immunotherapy

Cervical cancer (CC) is a common malignant tumour of the female reproductive system that is highly harmful to women's health. The efficacy of traditional surgery, radiotherapy and chemotherapy is limited, especially for recurrent and metastatic CC. With continuous progress in diagnostic and treatment technology, immunotherapy has become a new approach for treating CC and has become a new therapy for recurrent and metastatic CC. However, immunotherapy is not effective for all patients with CC. Therefore, factors related to immunotherapy efficacy in CC patients have become the focus of researchers. High-risk human papillomavirus (HPV) infection is an important factor that drives CC development and affects its progression and prognosis. Increasing attention has been given to the mechanism of the E5, E6 and E7 proteins, which are encoded by the HPV gene, in the occurrence and development of CC and their interaction with programmed cell death ligand-1/programmed cell death-1 (PD-L1/PD-1). Although some preliminary studies have been conducted on these topics, a comprehensive and systematic review of these topics is not available. This review comprehensively summarizes related articles from journals with impact factors greater than 3 and published in the past 5 years; it also reviews studies on the mechanism of HPV and CC, the mechanism of PD-L1/PD-1 axis regulation in CC, and the mechanism by which the interaction between HPV-related oncoproteins and the PD-L1/PD-1 pathway affects the development and prognosis of CC. This study provides theoretical support for the use of immunotherapies for CC, provides a basis for the selection of specific medications that target different HPV-related proteins, and provides a new perspective for the discovery of new immunotherapy targets for CC.

Increased spatial coupling of integrin and collagen IV in the immunoresistant clear-cell renal-cell carcinoma tumor microenvironment

BACKGROUND

Immunotherapy has improved survival for patients with advanced clear cell renal cell carcinoma (ccRCC), but resistance to therapy develops in most patients. We use cellular-resolution spatial transcriptomics in patients with immunotherapy naïve and exposed primary ccRCC tumors to better understand immunotherapy resistance.

RESULTS

Spatial molecular imaging of tumor and adjacent stroma samples from 21 tumors suggests that viable tumors following immunotherapy harbor more stromal CD8 + T cells and neutrophils than immunotherapy naïve tumors. YES1 is significantly upregulated in immunotherapy exposed tumor cells. Spatial GSEA shows that the epithelial-mesenchymal transition pathway is spatially enriched and the associated ligand-receptor transcript pair COL4A1-ITGAV has significantly higher autocorrelation in the stroma after exposure to immunotherapy. More integrin αV + cells are observed in immunotherapy exposed stroma on multiplex immunofluorescence validation. Compared to other cancers in TCGA, ccRCC tumors have the highest expression of both COL4A1 and ITGAV. Assessing bulk RNA expression and proteomic correlates in CPTAC databases reveals that collagen IV protein is more abundant in advanced stages of disease.

CONCLUSIONS

Spatial transcriptomics of samples of 3 patient cohorts with cRCC tumors indicates that COL4A1 and ITGAV are more autocorrelated in immunotherapy-exposed stroma compared to immunotherapy-naïve tumors, with high expression among fibroblasts, tumor cells, and endothelium. Further research is needed to understand changes in the ccRCC tumor immune microenvironment and explore potential therapeutic role of integrin after immunotherapy treatment.

The molecular features of lung cancer stem cells in dedifferentiation process-driven epigenetic alterations

Cancer stem cells (CSCs) may be dedifferentiated somatic cells following oncogenic processes, representing a subpopulation of cells able to promote tumor growth with their capacities for proliferation and self-renewal, inducing lineage heterogeneity, which may be a main cause of resistance to therapies. It has been shown that the "less differentiated process" may have an impact on tumor plasticity, particularly when non-CSCs may dedifferentiate and become CSC-like. Bidirectional interconversion between CSCs and non-CSCs has been reported in other solid tumors, where the inflammatory stroma promotes cell reprogramming by enhancing Wnt signaling through nuclear factor kappa B activation in association with intracellular signaling, which may induce cells' pluripotency, the oncogenic transformation can be considered another important aspect in the acquisition of "new" development programs with oncogenic features. During cell reprogramming, mutations represent an initial step toward dedifferentiation, in which tumor cells switch from a partially or terminally differentiated stage to a less differentiated stage that is mainly manifested by re-entry into the cell cycle, acquisition of a stem cell-like phenotype, and expression of stem cell markers. This phenomenon typically shows up as a change in the form, function, and pattern of gene and protein expression, and more specifically, in CSCs. This review would highlight the main epigenetic alterations, major signaling pathways and driver mutations in which CSCs, in tumors and specifically, in lung cancer, could be involved, acting as key elements in the differentiation/dedifferentiation process. This would highlight the main molecular mechanisms which need to be considered for more tailored therapies.

A Role for the Hippo/YAP1 Pathway in the Regulation of In Vitro Vasculogenic Mimicry in Glioblastoma Cells

The Hippo pathway plays a tumorigenic role in highly angiogenic glioblastoma (GBM), whereas little is known about clinically relevant Hippo pathway inhibitors' ability to target adaptive mechanisms involved in GBM chemoresistance. Their molecular impact was investigated here in vitro against an alternative process to tumour angiogenesis termed vasculogenic mimicry (VM) in GBM-derived cell models. In silico analysis of the downstream Hippo signalling members YAP1, TAZ and TEAD1 transcript levels in low-grade glioblastoma (LGG) and GBM tumour tissues was performed using GEPIA. TAZ transcript levels did not differ between the healthy and tumour tissues data analysed. In contrast, YAP1 transcript levels were elevated in GBM tissues, whereas TEAD1 levels were high in both LGG and GBM. All three Hippo pathway inhibitors tested, GNE7883, VT107 and IAG933 effectively inhibited U87 and U251 cell migration and in vitro VM as assessed on Cultrex matrix. YAP1 gene and protein expression were induced upon VM, and its translocation to the nucleus was inhibited by the Hippo pathway inhibitors tested. SiRNA-mediated transient silencing of YAP1 repressed cell migration, VM formation and CTGF and Cyr61 transcription. In conclusion, targeting of VM using Hippo pathway inhibitors could help circumvent GBM chemoresistance and effectively complement other brain cancer treatments.

The Hippo pathway as an antitumor target: time to focus on

INTRODUCTION

The Hippo signaling governs the expression of genes critically important for cell proliferation and survival. The components of this pathway are considered antitumor drug targets. However, the design of Hippo inhibitors is a challenge given the complexity of the network and redundancy of its elements.

AREAS COVERED

We review the current state-of-the-art in the structure of the Hippo pathway, the microenvironment-induced extracellular cues, the strategies to design pharmacological instruments for inactivation of the Hippo signaling using small molecular weight modulators, as well as the results of initial clinical trials.

EXPERT OPINION

One special characteristic of the Hippo signaling is the adverse role of phosphorylation: opposite to classical kinase cascades that activate the transcription factors, the Hippo kinases retain their partners in a transcriptionally inactive state. Therefore, approaches for pharmacological or genetic inhibition of Hippo protein kinases are counterproductive. The developing alternatives such as disruption of protein-protein interactions or PROTAC techniques are straightforward for preventing the Hippo signaling in cancer therapy.

Traditional Chinese medicine and its components effectively reduce resistance mediated by immune checkpoint inhibitors

Immunotherapy has become a global focus in cancer treatment and research, with promising results from targeting immune checkpoints in tumors like non-small cell lung cancer, colon cancer, and melanoma. However, resistance to immune checkpoint inhibitors (ICIs) remains a significant challenge. Traditional Chinese medicine (TCM), known for its low toxicity and minimal side effects, shows promise in enhancing cancer treatment when combined with modern therapies. This study reviews recent research on ICIs resistance mechanisms and highlights TCM's potential in overcoming this resistance, aiming to improve ICIs efficacy while minimizing toxicity.

The E3 ubiquitin ligase RNF6 facilitates the progression of cervical cancer by inhibiting the Hippo/Yap pathway

PURPOSE

Cervical cancer (CC), a significant global health threat, necessitates comprehensive understanding for improved therapeutic interventions. Many research indicates that dysregulation of the Hippo-YAP1 pathway leads to uncontrolled proliferation and invasion of tumor cells, promoting the progression of various cancers. This article aims to elucidate the role of RNF6 in CC and its regulation of the Hippo-YAP1 signaling pathway.

METHODS

The public tumor dataset analyses, immunohistochemistry, and western blotting were used to explore the expression of RNF6 in CC. Gain- and loss-of-function assays were conducted to elucidate the role of RNF6 in the proliferation and invasion of CC cells. Transcriptome sequencing was used to explore RNF6's role in cervical cancer, with validation of its regulation of the Hippo-YAP1 pathway through western blotting and RT-qPCR. Co-transfection of YAP overexpression plasmids into RNF6-silenced CC cells were preformed to confirm YAP1's pivotal role in RNF6-mediated CC progression. Animal experiments were preformed to further validate RNF6 interference's inhibitory effect on CC proliferation in vivo.

RESULTS

Clinical samples and bioinformatics analysis revealed high expression of RNF6 in CC, and closely associated with advanced FIGO (International Federation of Gynecology and Obstetrics) stage, larger tumor size, and poor prognosis. Cellular functional experiments demonstrate that RNF6 promotes the proliferation, invasion, and migration of CC cells, while knockdown of RNF6 yields the opposite effect. Transcriptome sequencing further reveals that RNF6 may promote CC progression through the Hippo-YAP signaling pathway. Western blotting and RT-qPCR further unveil that RNF6 enhances the upregulation of YAP1 protein levels, thereby activating downstream oncogenes CTGF and CYR61 transcription. Additionally, exogenous overexpression of YAP1 reverses the inhibitory effect of RNF6 silencing on CC proliferation and invasion. Furthermore, RNF6 interference significantly attenuates tumor growth in vivo experiments.

CONCLUSION

Our research reveals that RNF6 is highly expressed in CC, driving malignant progression by upregulating YAP1 protein expression and enhancing the transcription of downstream target genes CTGF and CYR61, offering potential therapeutic targets for CC treatment.

YAP-TEAD inhibition is associated with upregulation of an androgen receptor mediated transcription program providing therapeutic escape

Cholangiocarcinoma (CCA) is a highly aggressive form of liver cancer and is an increasing cause of cancer-related death worldwide. Despite its increasing incidence globally and alarming mortality, treatment options for CCA have largely remained unchanged, stressing the importance of developing new effective therapies. YAP activation is common in CCA, and its major transcriptional signaling partners are the TEAD proteins. CA3 is a small-molecule YAP-TEAD disrupter discovered utilizing a TEAD reporter assay. Utilizing CCA, gastric cancer cell lines, and patient-derived xenograft models (PDX), we demonstrate that CA3 is effective in inducing cell death and delaying tumor growth in both FGFR2 fusion and wild-type models. CA3 was associated with on-target decreases in YAP-TEAD target gene expression, TEAD reporter activity, and overall TEAD levels. Hippo pathway signaling was not altered as there was no change in YAP phosphorylation status in the cells exposed to CA3. RNA sequencing of gastric cancer and CCA models demonstrated upregulation of an androgen receptor-mediated transcriptional program following exposure to CA3 in five unique models tested. Consistent with this upstream regulator analysis, CA3 exposure in CCA cells was associated with increased AR protein levels, and combinatorial therapy with CA3 and androgen receptor blockade was associated with increased cancer cell death. CA3 behaves functionally as a YAP-TEAD disrupter in the models tested and demonstrated therapeutic efficacy. Exposure to CA3 was associated with compensatory androgen receptor signaling and dual inhibition improved the therapeutic effect.

YAP activation is robust to dilution

The concentration of many transcription factors exhibits high cell-to-cell variability due to differences in synthesis, degradation, and cell size. Whether the functions of these factors are robust to fluctuations in concentration, and how this may be achieved, is poorly understood. Across two independent panels of breast cancer cells, we show that the average whole cell concentration of YAP decreases as a function of cell area. However, the nuclear concentration distribution remains constant across cells grouped by size, across a 4-8 fold size range, implying unperturbed nuclear translocation despite the falling cell wide concentration. Both the whole cell and nuclear concentration was higher in cells with more DNA and CycA/PCNA expression suggesting periodic synthesis of YAP across the cell cycle offsets dilution due to cell growth and/or cell spreading. The cell area - YAP scaling relationship extended to melanoma and RPE cells. Integrative analysis of imaging and phospho-proteomic data showed the average nuclear YAP concentration across cell lines was predicted by differences in RAS/MAPK signalling, focal adhesion maturation, and nuclear transport processes. Validating the idea that RAS/MAPK and cell cycle regulate YAP translocation, chemical inhibition of MEK or CDK4/6 increased the average nuclear YAP concentration. Together, this study provides an example case, where cytoplasmic dilution of a protein, for example through cell growth, does not limit a cognate cellular function. Here, that same proteins translocation into the nucleus.

Strategies that regulate Hippo signaling pathway for novel anticancer therapeutics

As a highly conserved signaling network across different species, the Hippo pathway is involved in various biological processes. Dysregulation of the Hippo pathway could lead to a wide range of diseases, particularly cancers. Extensive researches have demonstrated the close association between dysregulated Hippo signaling and tumorigenesis as well as tumor progression. Consequently, targeting the Hippo pathway has emerged as a promising strategy for cancer treatment. In fact, there has been an increasing number of reports on small molecules that target the Hippo pathway, exhibiting therapeutic potential as anticancer agents. Importantly, some of Hippo signaling pathway inhibitors have been approved for the clinical trials. In this work, we try to provide an overview of the core components and signal transduction mechanisms of the Hippo signaling pathway. Furthermore, we also analyze the relationship between Hippo signaling pathway and cancers, as well as summarize the small molecules with proven anti-tumor effects in clinical trials or reported in literatures. Additionally, we discuss the anti-tumor potency and structure-activity relationship of the small molecule compounds, providing a valuable insight for further development of anticancer agents against this pathway.

Blocking CXCR4-CARM1-YAP axis overcomes osteosarcoma doxorubicin resistance by suppressing aerobic glycolysis

Osteosarcoma, recognized for its aggressiveness and resistance to chemotherapy, notably doxorubicin, poses significant treatment challenges. This comprehensive study investigated the CXCR4-CARM1-YAP signaling axis and its pivotal function in controlling aerobic glycolysis, which plays a crucial role in doxorubicin resistance. Detailed analysis of Dox-resistant 143b/MG63-DoxR cells has uncovered the overexpression of CXCR4. Utilizing a combination of molecular biology techniques including gene silencing, aerobic glycolysis assays such as Seahorse experiments, RNA sequencing, and immunofluorescence staining. The study provides insight into the mechanistic pathways involved. Results demonstrated that disrupting CXCR4 expression sensitizes cells to doxorubicin-induced apoptosis and alters glycolytic activity. Further RNA sequencing revealed that CARM1 modulated this effect through its influence on glycolysis, with immunofluorescence of clinical samples confirming the overexpression of CXCR4 and CARM1 in drug-resistant tumors. Chromatin immunoprecipitation studies further highlighted the role of CARM1, showing it to be regulated by methylation at the H3R17 site, which in turn affected YAP expression. Crucially, in vivo experiments illustrated that CARM1 overexpression could counteract the tumor growth suppression that resulted from CXCR4 inhibition. These insights revealed the intricate mechanisms at play in osteosarcoma resistance to doxorubicin and pointed toward potential new therapeutic strategies that could target this metabolic and signaling network to overcome drug resistance and improve patient outcomes.

Targeted degradation of specific TEAD paralogs by small molecule degraders

The transcription factors, TEAD1-4 together with their co-activator YAP/TAZ function as key downstream effectors of the Hippo pathway. Hyperactivation of TEAD-YAP/TAZ activity is observed in many human cancers. TEAD1-4 possess distinct physiological and pathological functions, with conserved sequences and structures. Targeting specific isoforms within TEAD1-4 can serve as valuable chemical probes for investigating TEAD-related functions in both development and diseases. We report the TEAD-targeting proteolysis targeting chimera (PROTAC), HC278, which achieves effective and specific targeting of TEAD1 and TEAD3 at low nanomolar doses while weakly degrading TEAD2 and TEAD4 at higher doses. Proteomic analysis of >6000 proteins confirmed their highly selective TEAD1 and TEAD3 degradation. Consistently, HC278 can suppress the proliferation of YAP-dependent NCI-H226 mesothelioma cells. Mechanistic exploration revealed that both CRBN and proteasome systems are involved in the TEAD degradation induced by HC278. Moreover, RNA-seq and Gene Set Enrichment Analysis (GSEA) revealed that the YAP signature genes such as CTGF, CYR61, and ANKRD1 are significantly downregulated by HC278 treatment. Overall, HC278 serves as a valuable chemical tool for unraveling the intricate biological roles of TEAD1 and TEAD3 and holds the potential as a lead compound for developing targeted therapy for TEAD1/3-driven pathologies.

Bioactive sphingolipids as emerging targets for signal transduction in cancer development

Sphingolipids, crucial components of cellular membranes, play a vital role in maintaining cellular structure and signaling integrity. Disruptions in sphingolipid metabolism are increasingly implicated in cancer development. Key bioactive sphingolipids, such as ceramides, sphingosine-1-phosphate (S1P), ceramide-1-phosphate (C1P), and glycosphingolipids, profoundly impact tumor biology. They influence the behavior of tumor cells, stromal cells, and immune cells, affecting tumor aggressiveness, angiogenesis, immune modulation, and extracellular matrix remodeling. Furthermore, abnormal expression of sphingolipids and their metabolizing enzymes modulates the secretion of tumor-derived extracellular vesicles (TDEs), which are key players in creating an immunosuppressive tumor microenvironment, remodeling the extracellular matrix, and facilitating oncogenic signaling within in situ tumors and distant pre-metastatic niches (PMNs). Understanding the role of sphingolipids in the biogenesis of tumor-derived extracellular vesicles (TDEs) and their bioactive contents can pave the way for new biomarkers in cancer diagnosis and prognosis, ultimately enhancing comprehensive tumor treatment strategies.

Mechanism and application of feedback loops formed by mechanotransduction and histone modifications

Mechanical stimulation is the key physical factor in cell environment. Mechanotransduction acts as a fundamental regulator of cell behavior, regulating cell proliferation, differentiation, apoptosis, and exhibiting specific signature alterations during the pathological process. As research continues, the role of epigenetic science in mechanotransduction is attracting attention. However, the molecular mechanism of the synergistic effect between mechanotransduction and epigenetics in physiological and pathological processes has not been clarified. We focus on how histone modifications, as important components of epigenetics, are coordinated with multiple signaling pathways to control cell fate and disease progression. Specifically, we propose that histone modifications can form regulatory feedback loops with signaling pathways, that is, histone modifications can not only serve as downstream regulators of signaling pathways for target gene transcription but also provide feedback to regulate signaling pathways. Mechanotransduction and epigenetic changes could be potential markers and therapeutic targets in clinical practice.

FATP5 modulates biological activity and lipid metabolism in prostate cancer through the TEAD4-mediated Hippo signaling

Introduction

Prostate cancer (PCa), one of the most prevalent malignant tumors in the genitourinary system, is characterized by distant metastasis and the development of castration-resistant prostate cancer (CRPC), which are major determinants of poor prognosis. Current treatment approaches for PCa primarily involve surgery and endocrine therapy, but effective strategies for managing distant metastasis and CRPC remain limited.

Methods

We utilized qPCR, WB, and other methods to measure the expression levels of respective proteins, concurrently assessing lipid metabolism to validate the role of FATP5 in lipid metabolism. Additionally, we employed bioinformatics analysis and WB techniques to explore the corresponding mechanisms.

Results

In this study, we conducted an analysis of clinical samples and public databases to identify differential expression of FATP5 and further investigated its association with clinical outcomes. Through biochemical and functional experiments, we elucidated the potential underlying mechanisms by which FATP5 facilitates the progression of PCa. Our findings demonstrate that specific upregulation of FATP5 significantly enhances proliferation, migration, and invasion of PCa cell lines, while also modulating lipid metabolism in PCa. Mechanistically, the expression of FATP5 is closely associated with the Hippo signaling pathway, as it promotes the nuclear accumulation of YAP1 by inhibiting AMPK and facilitating the activation of β-catenin and RHOA. Furthermore, the transcription of FATP5 is mediated by TEAD4, and this transcriptional activation requires the involvement of YAP1.

Discussion

FATP5 is highly expressed in prostate cancer and can enhance the biological activity and lipid metabolism of prostate cancer. We have also elucidated that FATP5 is regulated by the Hippo signaling pathway. This provides a new potential target for the treatment of prostate cancer.

YAP activation in Müller cells protects against NMDA-induced retinal ganglion cell injury by regulating Bcl-xL expression

Retinal neurodegeneration, characterized by retinal ganglion cell (RGC) death, is a leading cause of vision impairment and loss in blind diseases, such as glaucoma. Müller cells play crucial roles in maintaining retinal homeostasis. Thus, dysfunction of Müller cells has been implicated as one of the causes of retinal diseases. Yes-associated protein 1 (YAP), a nuclear effector of the Hippo pathway, regulates mammalian cell survival. In this study, we investigated the role of YAP in Müller cells during N-methyl-D-aspartic acid (NMDA)-induced excitotoxic RGC injury in rats. We found that YAP expression increased and was activated in Müller cells after NMDA-induced RGC injury. This YAP response was partly due to an increase in Yap mRNA levels, although it may be independent of the Hippo pathway and β-TrCP-mediated YAP degradation. Morphological analysis revealed that verteporfin, a selective YAP inhibitor, exacerbated NMDA-induced RGC degeneration, suggesting that YAP activation in Müller cells contributes to RGC survival in NMDA-treated retinas. Studies in the rat Müller cell line (rMC-1) demonstrated that overexpression of YAP increased the levels of Bcl-xL, while verteporfin decreased the levels of Bcl-xL and cell viability and increased the levels of cytochrome c released from mitochondria and cleaved caspase-3. Finally, we found that Bcl-xL expression increased slightly in NMDA-treated retinas, whereas intravitreal injection of verteporfin suppressed this increase. Our findings suggest that activated YAP in Müller cells protects against NMDA-induced RGC injury by upregulating Bcl-xL expression.