YAP and TAZ in Lung Cancer: Oncogenic Role and Clinical Targeting

EHMT2-mediated transcriptional reprogramming drives neuroendocrine transformation in non-small cell lung cancer

The transformation of lung adenocarcinoma to small cell lung cancer (SCLC) is a recognized resistance mechanism and a hindrance to therapies using epidermal growth factor receptor tyrosine kinase inhibitors (TKIs). The paucity of pretranslational/posttranslational clinical samples limits the deeper understanding of resistance mechanisms and the exploration of effective therapeutic strategies. Here, we developed preclinical neuroendocrine (NE) transformation models. Next, we identified a transcriptional reprogramming mechanism that drives resistance to erlotinib in NE transformation cell lines and cell-derived xenograft mice. We observed the enhanced expression of genes involved in the EHMT2 and WNT/β-catenin pathways. In addition, we demonstrated that EHMT2 increases methylation of the SFRP1 promoter region to reduce SFRP1 expression, followed by activation of the WNT/β-catenin pathway and TKI-mediated NE transformation. Notably, the similar expression alterations of EHMT2 and SFRP1 were observed in transformed SCLC samples obtained from clinical patients. Importantly, suppression of EHMT2 with selective inhibitors restored the sensitivity of NE transformation cell lines to erlotinib and delayed resistance in cell-derived xenograft mice. We identify a transcriptional reprogramming process in NE transformation and provide a potential therapeutic target for overcoming resistance to erlotinib.

YES1 as a potential target to overcome drug resistance in EGFR-deregulated non-small cell lung cancer

Epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs) such as gefitinib and osimertinib have primarily been used as first-line treatments for patients with EGFR-activating mutations in non-small cell lung cancer (NSCLC). Novel biomarkers are required to distinguish patients with lung cancer who are resistant to EGFR-TKIs. The aim of the study is to investigate the expression and functional role of YES1, one of the Src-family kinases, in EGFR-TKI-resistant NSCLC. YES1 expression was elevated in gefitinib-resistant HCC827 (HCC827/GR) cells, harboring EGFR mutations. Moreover, HCC827/GR cells exhibited increased reactive oxygen species (ROS) levels compared to those of the parent cells, resulting in the phosphorylation/activation of YES1 due to oxidation of the cysteine residue. HCC827/GR cells showed elevated expression levels of YES1-associated protein 1 (YAP1), NF-E2-related factor 2 (Nrf2), cancer stemness-related markers, and antioxidant proteins compared to those of the parent cells. Knockdown of YES1 in HCC827/GR cells suppressed YAP1 phosphorylation, leading to the inhibition of Bcl-2, Bcl-xL, and Cyclin D1 expression. Silencing YES1 markedly attenuated the proliferation, migration, and tumorigenicity of HCC827/GR cells. Dasatinib inhibited the proliferation of HCC827/GR cells by targeting YES1-mediated signaling pathways. Furthermore, the combination of gefitinib and dasatinib demonstrated a synergistic effect in suppressing the proliferation of HCC827/GR cells. Notably, YES1- and Nrf2-regulated genes showed a positive regulatory relationship in patients with lung cancer and in TKI-resistant NSCLC cell lines. Taken together, these findings suggest that modulation of YES1 expression and activity may be an attractive therapeutic strategy for the treatment of drug-resistant NSCLC.

Nuclear Localization of Yes-Associated Protein Is Associated With Tumor Progression in Cutaneous Melanoma

Yes-associated protein (YAP), an effector molecule of the Hippo signaling pathway, is expressed at high levels in cutaneous melanoma. However, the role of YAP in melanoma progression according to cellular localization is poorly understood. Tissues from 140 patients with invasive melanoma were evaluated by immunohistochemistry. Flow cytometry, western blotting, viability assays, wound healing assays, verteporfin treatment, and xenograft assays were conducted using melanoma cell lines B16F1 and B16F10 subjected to YapS127A transfection and siYap knockdown. Nuclear YAP localization was identified in 63 tumors (45.0%) and was more frequent than cytoplasmic YAP in acral lentiginous and nodular subtypes (P = .007). Compared with cytoplasmic YAP melanomas, melanomas with nuclear YAP had higher mitotic activity (P = .016), deeper invasion (P < .001), and more frequently metastasized to lymph nodes (P < .001) and distant organs (P < .001). Patients with nuclear YAP melanomas had poorer disease-free survival (P < .001) and overall survival (P < .001). Nuclear YAP was an independent risk factor for distant metastasis (hazard ratio: 3.206; 95% CI, 1.032-9.961; P = .044). Proliferative ability was decreased in siYapB16F1 (P < .001) and siYapB16F10 (P = .001) cells and increased in YapS127AB16F1 (P = .003) and YapS127AB16F10 (P = .002) cells. Cell cycle analysis demonstrated relative G1 retention in siYapB16F1 (P < .001) and siYapB16F10 (P < .001) cells and S retention in YapS127AB16F1 cells (P = .008). Wound healing assays showed that Yap knockdown inhibited cell invasion (siYapB16F1, P = .001; siYapB16F10, P < .001), whereas nuclear YAP promoted it (YapS127AB16F, P < .001; YapS127AB16F1, P = .017). Verteporfin, a direct YAP inhibitor, reduced cellular proliferation in B16F1 (P = .003) and B16F10 (P < .001) cells. Proliferative effects of nuclear YAP were confirmed in xenograft mice (P < .001). In conclusion, nuclear YAP in human melanomas showed subtype specificity and correlated with proliferative activity and proinvasiveness. It is expected that YAP becomes a useful prognostic marker, and its inhibition may be a potential therapy for melanoma patients.

Hippo-YAP/TAZ signalling coordinates adipose plasticity and energy balance by uncoupling leptin expression from fat mass

Adipose tissues serve as an energy reservoir and endocrine organ, yet the mechanisms that coordinate these functions remain elusive. Here, we show that the transcriptional coregulators, YAP and TAZ, uncouple fat mass from leptin levels and regulate adipocyte plasticity to maintain metabolic homeostasis. Activating YAP/TAZ signalling in adipocytes by deletion of the upstream regulators Lats1 and Lats2 results in a profound reduction in fat mass by converting mature adipocytes into delipidated progenitor-like cells, but does not cause lipodystrophy-related metabolic dysfunction, due to a paradoxical increase in circulating leptin levels. Mechanistically, we demonstrate that YAP/TAZ-TEAD signalling upregulates leptin expression by directly binding to an upstream enhancer site of the leptin gene. We further show that YAP/TAZ activity is associated with, and functionally required for, leptin regulation during fasting and refeeding. These results suggest that adipocyte Hippo-YAP/TAZ signalling constitutes a nexus for coordinating adipose tissue lipid storage capacity and systemic energy balance through the regulation of adipocyte plasticity and leptin gene transcription.

Molecular and Pathologic Characterization of YAP1-Expressing Small Cell Lung Cancer Cell Lines Leads to Reclassification as SMARCA4-Deficient Malignancies

PURPOSE

The classification of small cell lung cancer (SCLC) into distinct molecular subtypes defined by ASCL1, NEUROD1, POU2F3, or YAP1 (SCLC-A, -N, -P, or -Y) expression, paves the way for a personalized treatment approach. However, the existence of a distinct YAP1-expressing SCLC subtype remains controversial.

EXPERIMENTAL DESIGN

To better understand YAP1-expressing SCLC, the mutational landscape of human SCLC cell lines was interrogated to identify pathogenic alterations unique to SCLC-Y. Xenograft tumors, generated from cell lines representing the four SCLC molecular subtypes, were evaluated by a panel of pathologists who routinely diagnose thoracic malignancies. Diagnoses were complemented by transcriptomic analysis of primary tumors and human cell line datasets. Protein expression profiles were validated in patient tumor tissue.

RESULTS

Unexpectedly, pathogenic mutations in SMARCA4 were identified in six of eight SCLC-Y cell lines and correlated with reduced SMARCA4 mRNA and protein expression. Pathologist evaluations revealed that SMARCA4-deficient SCLC-Y tumors exhibited features consistent with thoracic SMARCA4-deficient undifferentiated tumors (SMARCA4-UT). Similarly, the transcriptional profile SMARCA4-mutant SCLC-Y lines more closely resembled primary SMARCA4-UT, or SMARCA4-deficient non-small cell carcinoma, than SCLC. Furthermore, SMARCA4-UT patient samples were associated with a YAP1 transcriptional signature and exhibited strong YAP1 protein expression. Together, we found little evidence to support a diagnosis of SCLC for any of the YAP1-expressing cell lines originally used to define the SCLC-Y subtype.

CONCLUSIONS

SMARCA4-mutant SCLC-Y cell lines exhibit characteristics consistent with SMARCA4-deficient malignancies rather than SCLC. Our findings suggest that, unlike ASCL1, NEUROD1, and POU2F3, YAP1 is not a subtype defining transcription factor in SCLC. See related commentary by Rekhtman, p. 1708.

Trans-3, 5, 4'-trimethoxystilbene restrains non-small-cell lung carcinoma progression via suppressing M2 polarization through inhibition of m6A modified circPACRGL-mediated Hippo signaling

BACKGROUND

Non-small-cell lung carcinoma (NSCLC) accounts for ∼85% of all lung carcinomas. Trans-3,5,4'-trimethoxystilbene (TMS) shows strong anti-tumor activity and induces tumor cell apoptosis. However, its function and mechanism in NSCLC still require investigation.

METHODS

PMA was used to treated THP-1 cells for macrophage differentiation. The abundance and m6A modification of circPACRGL were examined with qRT-PCR and MeRIP. Colony forming, transwell, wound healing, and Western blotting assays were applied to analyze proliferation, invasion, migration, and EMT. Macrophage polarization was determined through flow cytometry analysis of M1 and M2 markers. The interplay between circPACRGL, IGF2BP2 and YAP1 was validated by RNA pull-down and RIP assays. Mice received subcutaneous injection of NSCLC cells as a mouse model of subcutaneous tumor.

RESULTS

CircPACRGL was upregulated in NSCLC cells, but it was reduced by TMS treatment. CircPACRGL depletion blocked proliferation, migration, and invasion in H1299 and H1975 cells. TMS suppressed these malignant behaviors, but it was abolished by circPACRGL overexpression. In addition, NSCLC-derived exosomes delivered circPACRGL into THP-1 cells to promote its M2 polarization, but TMS inhibited these effects by downregulating exosomal circPACRGL. Mechanically, exosomal circPACRGL bound to IGF2BP2 to improve the stability of YAP1 mRNA and regulate Hippo signaling in polarized THP-1 cells. TMS inhibited NSCLC growth via suppressing Hippo signaling and M2 polarization in vivo.

CONCLUSION

TMS restrains M2 polarization and NSCLC progression by reducing circPACRGL and inhibiting exosomal circPACRGL-mediated Hippo signaling. Thus, these findings provide a novel mechanism underlying NSCLC progression and potential therapeutic targets.

Oncolytic Newcastle disease virus induced degradation of YAP through E3 ubiquitin ligase PRKN to exacerbate ferroptosis in tumor cells

Ferroptosis, a form of programmed cell death characterized by iron-dependent lipid peroxidation, has recently gained considerable attention in the field of cancer therapy. There is significant crosstalk between ferroptosis and several classical signaling pathways, such as the Hippo pathway, which suppresses abnormal growth and is frequently aberrant in tumor tissues. Yes-associated protein 1 (YAP), the core effector molecule of the Hippo pathway, is abnormally expressed and activated in a variety of malignant tumor tissues. We previously proved that the oncolytic Newcastle disease virus (NDV) activated ferroptosis to kill tumor cells. NDV has been used in tumor therapy; however, its oncolytic mechanism is not completely understood. In this study, we demonstrated that NDV exacerbated ferroptosis in tumor cells by inducing ubiquitin-mediated degradation of YAP at Lys90 through E3 ubiquitin ligase parkin (PRKN). Blocking YAP degradation suppressed NDV-induced ferroptosis by suppressing the expression of Zrt/Irt-like protein 14 (ZIP14), a metal ion transporter that regulates iron uptake. These findings demonstrate that NDV exacerbated ferroptosis in tumor cells by inducing YAP degradation. Our study provides new insights into the mechanism of NDV-induced ferroptosis and highlights the critical role that oncolytic viruses play in the treatment of drug-resistant cancers.IMPORTANCEThe oncolytic Newcastle disease virus (NDV) is being developed for use in cancer treatment; however, its oncolytic mechanism is still not completely understood. The Hippo pathway, which is a tumor suppressor pathway, is frequently dysregulated in tumor tissues due to aberrant yes-associated protein 1 (YAP) activation. In this study, we have demonstrated that NDV degrades YAP to induce ferroptosis and promote virus replication in tumor cells. Notably, NDV was found to induce ubiquitin-mediated degradation of YAP at Lys90 through E3 ubiquitin ligase parkin (PRKN). Our study reveals a new mechanism by which NDV induces ferroptosis and provides new insights into NDV as an oncolytic agent for cancer treatment.

Targeting SMAD-Dependent Signaling: Considerations in Epithelial and Mesenchymal Solid Tumors

SMADs are the canonical intracellular effector proteins of the TGF-β (transforming growth factor-β). SMADs translocate from plasma membrane receptors to the nucleus regulated by many SMAD-interacting proteins through phosphorylation and other post-translational modifications that govern their nucleocytoplasmic shuttling and subsequent transcriptional activity. The signaling pathway of TGF-β/SMAD exhibits both tumor-suppressing and tumor-promoting phenotypes in epithelial-derived solid tumors. Collectively, the pleiotropic nature of TGF-β/SMAD signaling presents significant challenges for the development of effective cancer therapies. Here, we review preclinical studies that evaluate the efficacy of inhibitors targeting major SMAD-regulating and/or -interacting proteins, particularly enzymes that may play important roles in epithelial or mesenchymal compartments within solid tumors.

The Matrix Stiffness Coordinates the Cell Proliferation and PD-L1 Expression via YAP in Lung Adenocarcinoma

The extracellular matrix (ECM) exerts physiological activity, facilitates cell-to-cell communication, promotes cell proliferation and metastasis, and provides mechanical support for tumor cells. The development of solid tumors is often associated with increased stiffness. A stiff ECM promotes mechanotransduction, and the predominant transcription factors implicated in this phenomenon are YAP/TAZ, β-catenin, and NF-κB. In this study, we aimed to investigate whether YAP is a critical mediator linking matrix stiffness and PD-L1 in lung adenocarcinoma. We confirmed that YAP, PD-L1, and Ki-67, a marker of cell proliferation, increase as the matrix stiffness increases in vitro using the lung adenocarcinoma cell lines PC9 and HCC827 cells. The knockdown of YAP decreased the expression of PD-L1 and Ki-67, and conversely, the overexpression of YAP increased the expression of PD-L1 and K-67 in a stiff-matrix environment (20.0 kPa). Additionally, lung cancer cells were cultured in a 3D environment, which provides a more physiologically relevant setting, and compared to the results obtained from 2D culture. Similar to the findings in 2D culture, it was confirmed that YAP influenced the expression of PD-L1 and K-67 in the 3D culture experiment. Our results suggest that matrix stiffness controls PD-L1 expression via YAP activation, ultimately contributing to cell proliferation.

Interstitial flow potentiates TGF-β/Smad-signaling activity in lung cancer spheroids in a 3D-microfluidic chip

Within the tumor microenvironment (TME), cancer cells use mechanotransduction pathways to convert biophysical forces to biochemical signals. However, the underlying mechanisms and functional significance of these pathways remain largely unclear. The upregulation of mechanosensitive pathways from biophysical forces such as interstitial flow (IF), leads to the activation of various cytokines, including transforming growth factor-β (TGF-β). TGF-β promotes in part via a Smad-dependent signaling pathway the epithelial-mesenchymal transition (EMT) in cancer cells. The latter process is linked to increased cancer cell motility and invasion. Current research models have limited ability to investigate the combined effects of biophysical forces (such as IF) and cytokines (TGF-β) in a 3D microenvironment. We used a 3D-matrix based microfluidic platform to demonstrate the potentiating effect of IF on exogenous TGF-β induced upregulation of the Smad-signaling activity and the expression of mesenchymal marker vimentin in A549 lung cancer spheroids. To monitor this, we used stably integrated fluorescent based reporters into the A549 cancer cell genome. Our results demonstrate that IF enhances exogenous TGF-β induced Smad-signaling activity in lung cancer spheroids embedded in a matrix microenvironment. In addition, we observed an increased cell motility for A549 spheroids when exposed to IF and TGF-β. Our 3D-microfluidic model integrated with real-time imaging provides a powerful tool for investigating cancer cell signaling and motility associated with invasion characteristics in a physiologically relevant TME.

YAP co-localizes with the mitotic spindle and midbody to safeguard mitotic division in lung-cancer cells

YES-associated protein (YAP) is a part of the Hippo pathway, with pivotal roles in several developmental processes and dual functionality as both a tumor suppressor and an oncogene. In the present study, we identified YAP activity as a microtubular scaffold protein that maintains the stability of the mitotic spindle and midbody by physically interacting with α-tubulin during mitotic progression. The interaction of YAP and α-tubulin was evident in co-immunoprecipitation assays, as well as observing their co-localization in the microtubular structure of the mitotic spindle and midbody in immunostainings. With YAP depletion, levels of ECT2, MKLP-1, and Aurora B are reduced, which is consistent with YAP functioning in midbody formation during cytokinesis. The concomitant decrease in α-tubulin and increase in acetyl-α-tubulin during YAP depletion occurred at the post-transcriptional level. This suggests that YAP maintains the stability of the mitotic spindle and midbody, which ensures appropriate chromosome segregation during mitotic division. The increase in acetyl-α-tubulin during YAP depletion may provide a lesion-halting mechanism in maintaining the microtubule structure. The depletion of YAP also results in multinuclearity and aneuploidy, which supports its role in stabilizing the mitotic spindle and midbody.

Targeting Hippo signaling in cancer: novel perspectives and therapeutic potential

As highly conserved among diverse species, Hippo signaling pathway regulates various biological processes, including development, cell proliferation, stem cell function, tissue regeneration, homeostasis, and organ size. Studies in the last two decades have provided a good framework for how these fundamental functions of Hippo signaling are tightly regulated by a network with numerous intracellular and extracellular factors. The Hippo signaling pathway, when dysregulated, may lead to a wide variety of diseases, especially cancer. There is growing evidence demonstrating that dysregulated Hippo signaling is closely associated with tumorigenesis, cancer cell invasion, and migration, as well as drug resistance. Therefore, the Hippo pathway is considered an appealing therapeutic target for the treatment of cancer. Promising novel agents targeting the Hippo signaling pathway for cancers have recently emerged. These novel agents have shown antitumor activity in multiple cancer models and demonstrated therapeutic potential for cancer treatment. However, the detailed molecular basis of the Hippo signaling-driven tumor biology remains undefined. Our review summarizes current advances in understanding the mechanisms by which Hippo signaling drives tumorigenesis and confers drug resistance. We also propose strategies for future preclinical and clinical development to target this pathway.

The Telluride YAP/TAZ and TEAD Workshop: A Small Meeting with a Big Impact

Funding the research needed to advance our understanding of rare cancers is very challenging [...].

A phase I/IB trial of binimetinib in combination with erlotinib in NSCLC harboring activating KRAS or EGFR mutations

BACKGROUND

Activating mutations in EGFR or KRAS are highly prevalent in NSCLC, share activation of the MAPK pathway and may be amenable to combination therapy to prevent negative feedback activation.

METHODS

In this phase 1/1B trial, we tested the combination of binimetinib and erlotinib in patients with advanced NSCLC with at least 1 prior line of treatment (unless with activating EGFR mutation which could be treatment-naïve). A subsequent phase 1B expansion accrued patients with either EGFR- or KRAS-mutation using the recommended phase 2 dose (RP2D) from Phase 1. The primary objective was to evaluate the safety of binimetinib plus erlotinib and establish the RP2D.

RESULTS

43 patients enrolled (dose-escalation = 23; expansion = 20). 17 harbored EGFR mutation and 22 had KRAS mutation. The RP2D was erlotinib 100 mg daily and binimetinib 15 mg BID × 5 days/week. Common AEs across all doses included diarrhea (69.8%), rash (44.2%), fatigue (32.6%), and nausea (32.6%), and were primarily grade 1/2. Among KRAS mutant patients, 1 (5%) had confirmed partial response and 8 (36%) achieved stable disease as best overall response. Among EGFR mutant patients, 9 were TKI-naïve with 8 (89%) having partial response, and 8 were TKI-pretreated with no partial responses and 1 (13%) stable disease as best overall response.

CONCLUSIONS

Binimetinib plus erlotinib demonstrated a manageable safety profile and modest efficacy including one confirmed objective response in a KRAS mutant patient. While clinical utility of this specific combination was limited, these results support development of combinations using novel small molecule inhibitors of RAS, selective EGFR- and other MAPK pathway inhibitors, many of which have improved therapeutic indices.

CLINICAL TRIAL REGISTRATION

NCT01859026.

The role of mechano-regulated YAP/TAZ in erectile dysfunction

Phosphodiesterase type 5 inhibitors (PDE5is) constitute the primary therapeutic option for treating erectile dysfunction (ED). Nevertheless, a substantial proportion of patients, approximately 30%, do not respond to PDE5i treatment. Therefore, new treatment methods are needed. In this study, we identified a pathway that contributes to male erectile function. We show that mechano-regulated YAP/TAZ signaling in smooth muscle cells (SMCs) upregulates adrenomedullin transcription, which relaxed the SMCs to maintain erection. Using single-nucleus RNA sequencing, we investigated how penile erection stretches the SMCs, inducing YAP/TAZ activity. Subsequently, we demonstrate that YAP/TAZ plays a role in erectile function and penile rehabilitation, using genetic lesions and various animal models. This mechanism relies on direct transcriptional regulation of adrenomedullin by YAP/TAZ, which in turn modulates penile smooth muscle contraction. Importantly, conventional PDE5i, which targets NO-cGMP signaling, does not promote erectile function in YAP/TAZ-deficient ED model mice. In contrast, by activating the YAP/TAZ-adrenomedullin cascade, mechanostimulation improves erectile function in PDE5i nonrespondent ED model rats and mice. Furthermore, using clinical retrospective observational data, we found that mechanostimulation significantly promotes erectile function in patients irrespective of PDE5i use. Our studies lay the groundwork for exploring the mechano-YAP/TAZ-adrenomedullin axis as a potential target in the treatment of ED.

Bufalin inhibits the proliferation of lung cancer cells by suppressing Hippo-YAP pathway

Lung cancer has high morbidity and mortality. This study demonstrated that Bufalin inhibits the proliferation of lung cancer cells in vivo / in vitro by suppressing Hippo-YAP pathway. Here, we found that Bufalin promoted the binding of LATS and YAP to elevate the level of YAP phosphorylation. Phosphorylated YAP could not successfully enter the nucleus to activate the expression of downstream proliferation-related target genes Cyr61 and CTGF, whereas the YAP retained in the cytoplasm further bound to β-TrCP and underwent ubiquitination and degradation. This study verified the key role of YAP in stimulating the proliferation of lung cancer and revealed the anticancer target of Bufalin. Therefore, this study provides a theoretical basis for the anticancer effect of Bufalin, and suggests that Bufalin can be a potential anticancer drug.

Scaffold hopping of N-benzyl-3,4,5-trimethoxyaniline: 5,6,7-Trimethoxyflavan derivatives as novel potential anticancer agents modulating hippo signaling pathway

Scaffold hopping of N-benzyl-3,4,5-trimethoxyaniline afforded 5,6,7-trimethoxyflavan derivatives that were efficiently synthesized in four linear steps. As lung cancer is the most lethal cancer, twenty-three synthesized compounds were evaluated against a panel of lung cancer cells. Amongst, compounds 8q and 8e showed interesting activity. Hence, compounds 8q and 8e were evaluated against panels of diverse cancers. Compounds 8q and 8e showed broad spectrum anticancer activity. However, compound 8q was more effective and, hence, was advanced for potency evaluation and characterization. Compound 8q showed comparable potencies to gefitinib, and oxaliplatin against lung and colorectal cancers, respectively, and superior potencies to temozolomide, dacarbazine, cisplatin, enzalutamide, methotrexate, imatinib against brain, skin, ovary, prostate, breast, and blood cancers, respectively. Compound 8q increased cleaved PARP, caspase 3, and 7 inducing apoptosis. In addition, it inhibited cyclins A, B₁, H and cdc25c, and increased p53 triggering cell cycle arrest in G₂/M phase. Moreover, it decreased YAP and increased LATS1 and p-mob1/mob1 activating hippo signaling. Furthermore, it decreased p-PI3K/PI3k, p-mTOR/mTOR and p-P70S6K/P70S6K inhibiting PI3k pathway. Together, these findings present compound 8q as a potential anticancer lead compound for further development of potential agents.

NDFIP1 limits cellular TAZ accumulation via exosomal sorting to inhibit NSCLC proliferation

NDFIP1 has been previously reported as a tumor suppressor in multiple solid tumors, but the function of NDFIP1 in NSCLC and the underlying mechanism are still unknown. Besides, the WW domain containing proteins can be recognized by NDFIP1, resulted in the loading of the target proteins into exosomes. However, whether WW domain-containing transcription regulator 1 (WWTR1, also known as TAZ) can be packaged into exosomes by NDFIP1 and if so, whether the release of this oncogenic protein via exosomes has an effect on tumor development has not been investigated to any extent. Here, we first found that NDFIP1 was low expressed in NSCLC samples and cell lines, which is associated with shorter OS. Then, we confirmed the interaction between TAZ and NDFIP1, and the existence of TAZ in exosomes, which requires NDFIP1. Critically, knockout of NDFIP1 led to TAZ accumulation with no change in its mRNA level and degradation rate. And the cellular TAZ level could be altered by exosome secretion. Furthermore, NDFIP1 inhibited proliferation in vitro and in vivo, and silencing TAZ eliminated the increase of proliferation caused by NDFIP1 knockout. Moreover, TAZ was negatively correlated with NDFIP1 in subcutaneous xenograft model and clinical samples, and the serum exosomal TAZ level was lower in NSCLC patients. In summary, our data uncover a new tumor suppressor, NDFIP1 in NSCLC, and a new exosome-related regulatory mechanism of TAZ.

Targeting YAP/TAZ in Combination with PD-L1 Immune Checkpoint Inhibitors in Non-Small Cell Lung Cancer (NSCLC)

The survival of non-small cell lung cancer (NSCLC) patients has improved in the last decade as a result of introducing new therapeutics, such as immune checkpoint inhibitors, in the clinic. Still, some NSCLC patients do not benefit from these therapies due to intrinsic resistance or the development of acquired resistance and their malignant disease progresses. Further research on the molecular underpinnings of NSCLC pathobiology is required in order to discover clinically relevant molecular targets that regulate tumor immunity and to develop reasonable therapeutic combinations that will promote the efficacy of immune checkpoint inhibitors. Yes-associated Protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ), the final effectors of the Hippo signaling transduction pathway, are emerging as key players in NSCLC development and progression. Herein, we overview studies that have investigated the oncogenic role of YAP/TAZ in NSCLC, focusing on immune evasion, and highlight the therapeutic potential of combining YAP/TAZ inhibitory agents with immune checkpoint inhibitors for the management of NSCLC patients.

Efficacy of immunotherapy in oncogene-driven non-small-cell lung cancer

For advanced metastatic non-small-lung cancer, the landscape of actionable driver alterations is rapidly growing, with nine targetable oncogenes and seven approvals within the last 5 years. This accelerated drug development has expanded the reach of targeted therapies, and it may soon be that a majority of patients with lung adenocarcinoma will be eligible for a targeted therapy during their treatment course. With these emerging therapeutic options, it is important to understand the existing data on immune checkpoint inhibitors (ICIs), along with their efficacy and safety for each oncogene-driven lung cancer, to best guide the selection and sequencing of various therapeutic options. This article reviews the clinical data on ICIs for each of the driver oncogene defined lung cancer subtypes, including efficacy, both for ICI as monotherapy or in combination with chemotherapy or radiation; toxicities from ICI/targeted therapy in combination or in sequence; and potential strategies to enhance ICI efficacy in oncogene-driven non-small-cell lung cancers.

The Biology and Therapeutic Potential of the Src-YAP Axis in Non-Small Cell Lung Cancer (NSCLC)

Non-small cell lung cancer (NSCLC) is the most common lung cancer type which accounts for the majority (~85%) of all lung cancer cases [...].

USP36 facilitates esophageal squamous carcinoma progression via stabilizing YAP

Esophageal squamous carcinoma (ESCC) is the major subtype of esophageal cancer in China, accounting for 90% of cases. Recent studies revealed that abnormalities in the Hippo/YAP axis are pervasive in ESCC and are recognized as the important driver of ESCC progression. Since the activity of Hippo signaling is controlled by phosphorylation cascade, it is a mystery why the major effector YAP is still over-activated when the cascade is inhibited. Several studies suggested that in addition to phosphorylation, other protein modifications such as ubiquitination also play important roles in manipulating Hippo/YAP signaling activity. Since YAP protein stability is controlled via an appropriate balance between E3 ubiquitin ligases and deubiquitinases, we performed deubiquitinase siRNA screening and identified USP36 as a deubiquitinase significantly related to Hippo/YAP signaling activity and ESCC progression. USP36 expression was elevated in ESCC samples and correlated with poor differentiation. USP36 expression was correlated with YAP protein levels in ESCC samples. Molecular studies demonstrated that USP36 associated with the YAP protein and enhanced YAP protein stability by blocking the K48-linked polyubiquitination of YAP. In conclusion, our study revealed a novel deubiquitinase in regulating Hippo signaling in ESCC, which could be an encouraging drug target for Hippo-driven ESCC.

Structure-based discovery of a novel small-molecule inhibitor of TEAD palmitoylation with anticancer activity

The paralogous oncogenic transcriptional coactivators YAP and TAZ are the distal effectors of the Hippo signaling pathway, which plays a critical role in cell proliferation, survival and cell fate specification. They are frequently deregulated in most human cancers, where they contribute to multiple aspects of tumorigenesis including growth, metabolism, metastasis and chemo/immunotherapy resistance. Thus, they provide a critical point for therapeutic intervention. However, due to their intrinsically disordered structure, they are challenging to target directly. Since YAP/TAZ exerts oncogenic activity by associating with the TEAD1-4 transcription factors, to regulate target gene expression, YAP activity can be controlled indirectly by regulating TEAD1-4. Interestingly, TEADs undergo autopalmitoylation, which is essential for their stability and function, and small-molecule inhibitors that prevent this posttranslational modification can render them unstable. In this article we report discovery of a novel small molecule inhibitor of YAP activity. We combined structure-based virtual ligand screening with biochemical and cell biological studies and identified JM7, which inhibits YAP transcriptional reporter activity with an IC50 of 972 nMoles/Ltr. Further, it inhibits YAP target gene expression, without affecting YAP/TEAD localization. Mechanistically, JM7 inhibits TEAD palmitoylation and renders them unstable. Cellular thermal shift assay revealed that JM7 directly binds to TEAD1-4 in cells. Consistent with the inhibitory effect of JM7 on YAP activity, it significantly impairs proliferation, colony-formation and migration of mesothelioma (NCI-H226), breast (MDA-MB-231) and ovarian (OVCAR-8) cancer cells that exhibit increased YAP activity. Collectively, these results establish JM7 as a novel lead compound for development of more potent inhibitors of TEAD palmitoylation for treating cancer.

P130cas-FAK interaction is essential for YAP-mediated radioresistance of non-small cell lung cancer

Based on the RNA-sequencing data, previous studies revealed that extracellular matrix receptor interaction and focal adhesion signaling pathways were enriched in radioresistant non-small cell lung cancer (NSCLC) cell lines. As the principal members of these signaling pathways, recent studies showed that FAK controlled YAP's nuclear translocation and activation in response to mechanical activation. However, the underlying mechanisms are largely unknown. This study was designed to determine whether P130cas plays a role in FAK-YAP axis-mediated radioresistance. We found that P130cas promoted proliferation, altered the cell cycle profile, and enhanced tumor growth using cell lines and xenograft mouse models. After treating the cell lines and xenograft models with a single dose of 5 Gy irradiation, we observed that P130cas effectively induced radioresistance in vitro and in vivo. We confirmed that P130cas interacted with and promoted YAP stabilization, thereby facilitating YAP's activation and nuclear translocation and downregulating the radiosensitivity of NSCLC. Our data also revealed that P130cas and FAK directly interacted with each other and worked together to regulate YAP's activation and nuclear translocation. Furthermore, the present study identified that P130cas, FAK and YAP formed a triple complex to induce radioresistance. Using P130cas-ΔSH3, FAK- P712/715A mutant, YAP-ΔSH3bm and YAP-ΔWW mutant, our results showed that targeting P130cas-FAK interaction may be a more cost-effective way to overcome the YAP activation mediated radioresistance in NSCLC. Using the data of the public database and our clinical samples, the present study suggested that the expression of P130cas correlated with YAP expression and indicated a poor overall response rate of NSCLC patients who underwent radiation therapy. Overall, our study extends the knowledge of FAK-YAP interaction and provides new insight into understanding the underlying mechanisms to overcome the radioresistance of NSCLC.

Human Papillomavirus 16 E6 and E7 Oncoproteins Alter the Abundance of Proteins Associated with DNA Damage Response, Immune Signaling and Epidermal Differentiation

The high-risk human papillomaviruses are oncogenic viruses associated with almost all cases of cervical carcinomas, and increasing numbers of anal, and oral cancers. Two oncogenic HPV proteins, E6 and E7, are capable of immortalizing keratinocytes and are required for HPV associated cell transformation. Currently, the influence of these oncoproteins on the global regulation of the host proteome is not well defined. Liquid chromatography coupled with quantitative tandem mass spectrometry using isobaric-tagged peptides was used to investigate the effects of the HPV16 oncoproteins E6 and E7 on protein levels in human neonatal keratinocytes (HEKn). Pathway and gene ontology enrichment analyses revealed that the cells expressing the HPV oncoproteins have elevated levels of proteins related to interferon response, inflammation and DNA damage response, while the proteins related to cell organization and epithelial development are downregulated. This study identifies dysregulated pathways and potential biomarkers associated with HPV oncoproteins in primary keratinocytes which may have therapeutic implications. Most notably, DNA damage response pathways, DNA replication, and interferon signaling pathways were affected in cells transduced with HPV16 E6 and E7 lentiviruses. Moreover, proteins associated with cell organization and differentiation were significantly downregulated in keratinocytes expressing HPV16 E6 + E7. High-risk HPV E6 and E7 oncoproteins are necessary for the HPV-associated transformation of keratinocytes. However their influence on the global dysregulation of keratinocyte proteome is not well documented. Here shotgun proteomics using TMT-labeling detected over 2500 significantly dysregulated proteins associated with E6 and E7 expression. Networks of proteins related to interferon response, inflammation and DNA damage repair pathways were altered.

YAP and TAZ: Monocorial and bicorial transcriptional co-activators in human cancers

The transcriptional regulators YAP and TAZ are involved in numerous physiological processes including organ development, growth, immunity and tissue regeneration. YAP and TAZ dysregulation also contribute to tumorigenesis, thereby making them attractive cancer therapeutic targets. Arbitrarily, YAP and TAZ are often considered as a single protein, and are referred to as YAP/TAZ in most studies. However, increasing experimental evidences documented that YAP and TAZ perform both overlapping and distinct functions in several physiological and pathological processes. In addition to regulating distinct processes, YAP and TAZ are also regulated by distinct upstream cues. The aim of the review is to describe the distinct roles of YAP and TAZ focusing particularly on cancer. Therapeutic strategies targeting either YAP and TAZ proteins or only one of them should be carefully evaluated. Selective targeting of YAP or TAZ may in fact impair different pathways and determine diverse clinical outputs.

The interplay between noncoding RNA and YAP/TAZ signaling in cancers: molecular functions and mechanisms

The Hippo signaling pathway was found coordinately modulates cell regeneration and organ size. Its dysregulation contributes to uncontrolled cell proliferation and malignant transformation. YAP/TAZ are two critical effectors of the Hippo pathway and have been demonstrated essential for the initiation or growth of most tumors. Noncoding RNAs (ncRNAs), including miRNAs, lncRNAs, and circRNAs, have been shown to play critical roles in the development of many cancers. In the past few decades, a growing number of studies have revealed that ncRNAs can directly or indirectly regulate YAP/TAZ signaling. YAP/TAZ also regulate ncRNAs expression in return. This review summarizes the interactions between YAP/TAZ signaling and noncoding RNAs together with their biological functions on cancer progression. We also try to describe the complex feedback loop existing between these components.

Functions of Yes-association protein (YAP) in cancer progression and anticancer therapy resistance

The Hippo pathway, a highly conserved kinase cascade, regulates cell proliferation, apoptosis, organ size, and tissue homeostasis. Dysregulation of this pathway reportedly plays an important role in the progression of various human cancers. Yes-association protein (YAP), the Hippo pathway’s core effector, is considered a marker for cancer therapy and patient prognosis. In addition, studies have indicated that YAP is involved in promoting anticancer drug resistance. This review summarizes current knowledge on YAP’s role in cancer progression, anticancer drug resistance, and advances in the development of YAP-targeting drugs. A thorough understanding of the complex interactions among molecular, cellular, and environmental factors concerning YAP function in cancer progression may provide new insight into the underlying mechanism of anticancer drug resistance. It might lead to improved prognosis through novel combined therapies.

A Potent Histone Deacetylase Inhibitor MPT0E028 Mitigates Emphysema Severity via Components of the Hippo Signaling Pathway in an Emphysematous Mouse Model

Background

Chronic obstructive pulmonary disease (COPD) is a major cause of chronic mortality. The objective of this study was to investigate the therapeutic potential of a novel potent histone deacetylase (HDAC) inhibitor MPT0E028 on emphysema.

Materials and Methods

A mouse model of porcine pancreatic elastase (PPE)-induced emphysema was orally administered 0, 25, or 50 mg/kg body weight (BW) of the MPT0E028 five times/week for 3 weeks. Pulmonary function, mean linear intercept (MLI), chest CT, inflammation, yes-associated protein (YAP), transcriptional coactivator with PDZ-binding motif (TAZ), surfactant protein C (SPC), T1-α, p53, and sirtuin 1 (SIRT1) levels were examined.

Results

50 mg/kg BW of the MPT0E028 significantly decreased the tidal volume in emphysematous mice (p < 0.05). Emphysema severity was significantly reduced from 26.65% (PPE only) to 13.83% (50 mg/kg BW of the MPT0E028). Total cell counts, neutrophils, lymphocytes, and eosinophils significantly decreased with both 25 and 50 mg/kg BW of the MPT0E028 (p < 0.05). Also, 50 mg/kg BW of the MPT0E028 significantly decreased the levels of KC, TNF-α, and IL-6 in lung tissues and serum (p < 0.05). Expressions of p-TAZ/TAZ in lung tissues significantly decreased with 50 mg/kg BW of the MPT0E028 (p < 0.05). Expressions of p53 significantly decreased in alveolar regions with 50 mg/kg BW of the MPT0E028 (p < 0.05), and the expression of SPC increased in alveolar regions with 50 mg/kg BW of the MPT0E028 (p < 0.05).

Conclusions

Our study showed that the potent HDAC inhibitor MPT0E028 reduced the severity and inflammation of emphysema with improvement in lung function, which could be regulated by Hippo signaling pathway. The MPT0E028 may have therapeutic potential for emphysema.

Matrix stiffness regulates macrophage polarization in atherosclerosis

Atherosclerosis is a chronic inflammatory disease and the pathological basis of many fatal cardiovascular diseases. Macrophages, the main inflammatory cells in atherosclerotic plaque, have a paradox role in disease progression. In response to different microenvironments, macrophages mainly have two polarized directions: pro-inflammatory macrophages and anti-inflammatory macrophages. More and more evidence shows that macrophage is mechanosensitive and matrix stiffness regulate macrophage phenotypes in atherosclerosis. However, the molecular mechanism of matrix stiffness regulating macrophage polarization still lacks in-depth research, which hinders the development of new anti-atherosclerotic therapies. In this review, we discuss the important role of matrix stiffness in regulating macrophage polarization through mechanical signal transduction (Hippo, Piezo, cytoskeleton, and integrin) and epigenetic mechanisms (miRNA, DNA methylation, and histone). We hope to provide a new perspective for atherosclerosis therapy by targeting matrix stiffness and macrophage polarization.

PLOD3 regulates the expression of YAP1 to affect the progression of non-small cell lung cancer via the PKCδ/CDK1/LIMD1 signaling pathway

Procollagen-lysine, 2-oxoglutarate 5-dioxygenase (PLOD3) is a crucial oncogene in human lung cancer, whereas protein kinase C δ (PKCδ) acts as a tumor suppressor. In this study, we aimed to explore the regulation by PLOD3 on the expression of YAP1 to affect the progression of non-small cell lung cancer (NSCLC) via the PKCδ/CDK1/LIMD1 signaling pathway. We found that PLOD3, CDK1, and YAP1 were highly expressed, while LIMD1 was poorly expressed in NSCLC tissues. Mechanistic investigation demonstrated that silencing PLOD3 promoted the cleavage of PKCδ in a caspase-dependent manner to generate a catalytically active fragment cleaved PKCδ, enhanced phosphorylation levels of CDK1, and LIMD1 but suppressed nuclear translocation of YAP1. Furthermore, functional experimental results suggested that loss of PLOD3 led to increased phosphorylation levels of CDK1 and LIMD1 and downregulated YAP1, thereby suppressing the proliferation, colony formation, cell cycle entry, and resistance to apoptosis of NSCLC cells in vitro and inhibiting tumor growth in vivo. Taken together, these results show that PLOD3 silencing activates the PKCδ/CDK1/LIMD1 signaling pathway to prevent the progression of NSCLC, thus providing novel insight into molecular targets for treating NSCLC.

Knowledge graph-based recommendation framework identifies drivers of resistance in EGFR mutant non-small cell lung cancer

Resistance to EGFR inhibitors (EGFRi) presents a major obstacle in treating non-small cell lung cancer (NSCLC). One of the most exciting new ways to find potential resistance markers involves running functional genetic screens, such as CRISPR, followed by manual triage of significantly enriched genes. This triage process to identify ‘high value’ hits resulting from the CRISPR screen involves manual curation that requires specialized knowledge and can take even experts several months to comprehensively complete. To find key drivers of resistance faster we build a recommendation system on top of a heterogeneous biomedical knowledge graph integrating pre-clinical, clinical, and literature evidence. The recommender system ranks genes based on trade-offs between diverse types of evidence linking them to potential mechanisms of EGFRi resistance. This unbiased approach identifies 57 resistance markers from >3,000 genes, reducing hit identification time from months to minutes. In addition to reproducing known resistance markers, our method identifies previously unexplored resistance mechanisms that we prospectively validate.

Resistance to EGFR inhibitors presents a major obstacle in treating non-small cell lung cancer. Here, the authors develop a recommender system ranking genes based on trade-offs between diverse types of evidence linking them to potential mechanisms of EGFRi resistance.

Ionizing radiation-induced long noncoding RNA CRYBG3 regulates YAP/TAZ through mechanotransduction

Mechanotransduction sensing of tissue architecture and cellular microenvironment is a fundamental regulator of cell fate, including cancer. Meanwhile, long noncoding RNAs (lncRNAs) play multifunctions during cancer development and treatment. However, the link between lncRNAs and cellular mechanotransduction in the context of cancer progression has not yet been elucidated. In this study, using atomic force microscopy (AFM), we find that ionizing radiation reduces tumor stiffness. Ionizing radiation-induced lncRNA CRYBG3 can blunt YAP/TAZ activity through interference with mechanotransduction, resulting in the inhibition of cell proliferation, invasion, and metastasis of lung cancer cells. In vivo, we found that loss of lncRNA CRYBG3 could power the tumor initiation and metastasis ability, but this was abolished by concomitant deplete TAZ. At the molecular level, lncRNA CRYBG3 that in turn dysregulates F-actin organization, activates the LATS1/2 kinase, all in all resulting in YAP/TAZ nuclear exclusion. Our research proposes that lncRNA CRYBG3 is a mediator of radiotherapy through its control of cancer-tissue mechanotransduction and wiring YAP/TAZ activity to control tumor growth and metastasis.

Hippo Pathway in Regulating Drug Resistance of Glioblastoma

Glioblastoma (GBM) represents the most common and malignant tumor of the Central Nervous System (CNS), affecting both children and adults. GBM is one of the deadliest tumor types and it shows a strong multidrug resistance (MDR) and an immunosuppressive microenvironment which remain a great challenge to therapy. Due to the high recurrence of GBM after treatment, the understanding of the chemoresistance phenomenon and how to stimulate the antitumor immune response in this pathology is crucial. The deregulation of the Hippo pathway is involved in tumor genesis, chemoresistance and immunosuppressive nature of GBM. This pathway is an evolutionarily conserved signaling pathway with a kinase cascade core, which controls the translocation of YAP (Yes-Associated Protein)/TAZ (Transcriptional Co-activator with PDZ-binding Motif) into the nucleus, leading to regulation of organ size and growth. With this review, we want to highlight how chemoresistance and tumor immunosuppression work in GBM and how the Hippo pathway has a key role in them. We linger on the role of the Hippo pathway evaluating the effect of its de-regulation among different human cancers. Moreover, we consider how different pathways are cross-linked with the Hippo signaling in GBM genesis and the hypothetical mechanisms responsible for the Hippo pathway activation in GBM. Furthermore, we describe various drugs targeting the Hippo pathway. In conclusion, all the evidence described largely support a strong involvement of the Hippo pathway in gliomas progression, in the activation of chemoresistance mechanisms and in the development of an immunosuppressive microenvironment. Therefore, this pathway is a promising target for the treatment of high grade gliomas and in particular of GBM.

The role of ferroptosis in lung cancer

Lung cancer is one of the most common cancers in the world. Although medical treatment has made impressive progress in recent years, it is still one of the leading causes of cancer-related deaths in men and women. Ferroptosis is a type of non-apoptotic cell death modality, usually characterized by iron-dependent lipid peroxidation, rather than caspase-induced protein cleavage. Excessive or lack of ferroptosis is associated with a variety of diseases, including cancer and ischaemia-reperfusion injury. Recent preclinical evidence suggests that targeting ferroptotic pathway is a potential strategy for the treatment of lung cancer. In this review, we summarize the core mechanism and regulatory network of ferroptosis in lung cancer cells, and highlight ferroptosis induction-related tumor therapies. The reviewed information may provide new insights for targeted lung cancer therapy.

The anticarcinogenic and anticancer effects of the dietary flavonoid, morin: Current status, challenges, and future perspectives

Flavonoids constitute one of the most important classes of polyphenols, which have been found to have a wide range of biological activities such as anticancer effects. A large body of evidence demonstrates that morin as a pleiotropic dietary flavonoid possesses potent anticarcinogenic and anticancer activities with minimal toxicity against normal cells. The present review comprehensively elaborates the molecular mechanisms underlying antitumorigenic and anticancer effects of morin. Morin exerts its anticarcinogenic effects through multiple cancer preventive mechanisms, including reduction of oxidative stress, activation of phase II enzymes, induction of apoptosis, attenuation of inflammatory mediators, and downregulation of p-Akt and NF-κB expression. A variety of molecular targets and signaling pathways such as apoptosis, cell cycle, reactive oxygen species (ROS), matrix metalloproteinases (MMPs), epithelial-mesenchymal transition (EMT), and microRNAs (miRNAs) as well as signal transducer and activator of transcription 3 (STAT3), NF-κB, phosphatidylinositol 3-kinase (PI3K)/Akt, mitogen-activated protein kinase (MAPK), and Hippo pathways have been found to be involved in the anticancer effects of morin. In the adjuvant therapy, morin has been shown to have synergistic anticancer effects with several chemotherapeutic drugs. The findings of this review indicate that morin can act as a promising chemopreventive and chemotherapeutic agent.

Decoding m6A mRNA methylation by reader proteins in cancer

N⁶-methyladenosine (m⁶A), the most prevalent internal modification in eukaryotic mRNAs, regulates gene expression at the post-transcriptional level. The reader proteins of m⁶A, mainly YTH domain-containing proteins, specifically recognize m⁶A-modified mRNAs and regulate their metabolism. Recent studies have highlighted essential roles of m⁶A readers in the initiation and development of human cancers. In this review, we summarize recent findings about the biological functions of YTH domain proteins in cancers, the underlying mechanisms, and clinical implications. Gene expression reprogramming by dysregulated m⁶A reader proteins offers potential targets for cancer treatment, while targeted m⁶A editors and readers provide tools to manipulate m⁶A metabolism in cancers.

Inhibition of yes-associated protein suppresses migration, invasion, and metastasis in non-small cell lung cancer in vitro and in vivo

Non-small cell lung cancer (NSCLC) is a highly aggressive cancer with one of the most prevalent malignant tumors. Metastasis in NSCLC is the major cause of treatment failure and cancer-related deaths. Yes-associated protein (YAP) is a transcriptional coactivator regulated by the evolutionarily conserved Hippo signaling pathway that regulates organ size, growth, and regeneration. YAP is highly expressed in several malignant tumor types. Furthermore, YAP promotes tumor initiation and/or progression in various types of cancer. However, it is unclear whether YAP contributes to the metastasis in NSCLC and serves as a useful therapeutic target. Here, we investigated whether levels of YAP correlate with metastatic phenotype in NSCLC cells and serve as a useful therapeutic target. We found that high levels of YAP associate with high cell migration, invasion, and metastasis in NSCLC cell lines. Furthermore, YAP siRNA decreased the migration and invasion in NSCLC cells. Additionally, verteporfin, an agent used for the treatment of symptomatic polypoidal choroidal vasculopathy, decreased the expression of YAP and inhibited migration, invasion, and metastasis in NSCLC cells. Thus, the study suggests that targeting YAP may present a new avenue to develop therapeutics against metastasis in NSCLC and that verteporfin has potential molecular therapeutic strategy for the treatment of metastatic NSCLC.

Multi-omic analysis of lung tumors defines pathways activated in neuroendocrine transformation

Lineage plasticity is implicated in treatment resistance in multiple cancers. In lung adenocarcinomas (LUADs) amenable to targeted therapy, transformation to small cell lung cancer (SCLC) is a recognized resistance mechanism. Defining molecular mechanisms of neuroendocrine (NE) transformation in lung cancer has been limited by a paucity of pre-/post-transformation clinical samples. Detailed genomic, epigenomic, transcriptomic, and protein characterization of combined LUAD/SCLC tumors, as well as pre-/post-transformation samples, support that NE transformation is primarily driven by transcriptional reprogramming rather than mutational events. We identify genomic contexts in which NE transformation is favored, including frequent loss of the 3p chromosome arm. We observed enhanced expression of genes involved in PRC2 complex and PI3K/AKT and NOTCH pathways. Pharmacological inhibition of the PI3K/AKT pathway delayed tumor growth and NE transformation in an EGFR-mutant patient-derived xenograft model. Our findings define a novel landscape of potential drivers and therapeutic vulnerabilities of neuroendocrine transformation in lung cancer.

PDS5B inhibits cell proliferation, migration, and invasion via upregulation of LATS1 in lung cancer cells

PDS5B (precocious dissociation of sisters 5B) plays a pivotal role in carcinogenesis and progression. However, the biological functions of PDS5B in lung cancer and its underlying mechanisms are not fully elucidated. In the present study, we used MTT assays, wound-healing assays, and transwell migration and invasion approach to examine the cell viability, migration, and invasion of non-small cell lung cancer (NSCLC) cells after PDS5B modulation. Moreover, we investigated the function of PDS5B overexpression in vivo. Furthermore, we detected the expression of PDS5B in tissue samples of lung cancer patients by immunohistochemical study. We found that upregulation of PDS5B repressed cell viability, migration, and invasion in NSCLC cells, whereas downregulation of PDS5B had the opposite effects. We also observed that PDS5B overexpression retarded tumor growth in nude mice. Notably, PDS5B positively regulated LATS1 expression in NSCLC cells. Strikingly, low expression of PDS5B was associated with lymph node metastasis in lung cancer patients. Our findings suggest that PDS5B might be a therapeutic target for lung cancer.

An Updated Understanding of the Role of YAP in Driving Oncogenic Responses

Simple Summary

In 2020, the global cancer database GLOBOCAN estimated 19.3 million new cancer cases worldwide. The discovery of targeted therapies may help prognosis and outcome of the patients affected, but the understanding of the plethora of highly interconnected pathways that modulate cell transformation, proliferation, invasion, migration and survival remains an ambitious goal. Here we propose an updated state of the art of YAP as the key protein driving oncogenic response via promoting all those steps at multiple levels. Of interest, the role of YAP in immunosuppression is a field of evolving research and growing interest and this summary about the current pharmacological therapies impacting YAP serves as starting point for future studies.

Abstract

Yes-associated protein (YAP) has emerged as a key component in cancer signaling and is considered a potent oncogene. As such, nuclear YAP participates in complex and only partially understood molecular cascades that are responsible for the oncogenic response by regulating multiple processes, including cell transformation, tumor growth, migration, and metastasis, and by acting as an important mediator of immune and cancer cell interactions. YAP is finely regulated at multiple levels, and its localization in cells in terms of cytoplasm–nucleus shuttling (and vice versa) sheds light on interesting novel anticancer treatment opportunities and putative unconventional functions of the protein when retained in the cytosol. This review aims to summarize and present the state of the art knowledge about the role of YAP in cancer signaling, first focusing on how YAP differs from WW domain-containing transcription regulator 1 (WWTR1, also named as TAZ) and which upstream factors regulate it; then, this review focuses on the role of YAP in different cancer stages and in the crosstalk between immune and cancer cells as well as growing translational strategies derived from its inhibitory and synergistic effects with existing chemo-, immuno- and radiotherapies.

Simultaneous Pharmacologic Inhibition of Yes-Associated Protein 1 and Glutaminase 1 via Inhaled Poly(Lactic-co-Glycolic) Acid-Encapsulated Microparticles Improves Pulmonary Hypertension

Background Pulmonary hypertension (PH) is a deadly disease characterized by vascular stiffness and altered cellular metabolism. Current treatments focus on vasodilation and not other root causes of pathogenesis. Previously, it was demonstrated that glutamine metabolism, as catalyzed by GLS1 (glutaminase 1) activity, is mechanoactivated by matrix stiffening and the transcriptional coactivators YAP1 (yes-associated protein 1) and transcriptional coactivator with PDZ-binding motif (TAZ), resulting in pulmonary vascular proliferation and PH. Pharmacologic inhibition of YAP1 (by verteporfin) or glutaminase (by CB-839) improved PH in vivo. However, systemic delivery of these agents, particularly YAP1 inhibitors, may have adverse chronic effects. Furthermore, simultaneous use of pharmacologic blockers may offer additive or synergistic benefits. Therefore, a strategy that delivers these drugs in combination to local lung tissue, thus avoiding systemic toxicity and driving more robust improvement, was investigated. Methods and Results We used poly(lactic-co-glycolic) acid polymer-based microparticles for delivery of verteporfin and CB-839 simultaneously to the lungs of rats suffering from monocrotaline-induced PH. Microparticles released these drugs in a sustained fashion and delivered their payload in the lungs for 7 days. When given orotracheally to the rats weekly for 3 weeks, microparticles carrying this drug combination improved hemodynamic (right ventricular systolic pressure and right ventricle/left ventricle+septum mass ratio), histologic (vascular remodeling), and molecular markers (vascular proliferation and stiffening) of PH. Importantly, only the combination of drug delivery, but neither verteporfin nor CB-839 alone, displayed significant improvement across all indexes of PH. Conclusions Simultaneous, lung-specific, and controlled release of drugs targeting YAP1 and GLS1 improved PH in rats, addressing unmet needs for the treatment of this deadly disease.

Hippo signaling pathway in companion animal diseases, an under investigated signaling cascade

The Hippo pathway is a highly conserved kinase cascade in mammals with the proteins YAP and TAZ as its most important downstream effectors that shuttle between cytoplasma and nucleus. It has a crucial role in processes such as embryogenesis, organ size control, homeostasis and tissue regeneration, where mechanosensing and/or cell-cell interactions are involved. As the pathway is associated with many essential functions in the body, its dysregulation is related to many diseases. In contrast to human pathology, a PubMed-search on Hippo, YAP/TAZ and companion animals (horse, equine, dog, canine, cat, feline) retrieved few publications. Because of its high level of functional conservation, it is anticipated that also in veterinary sciences aberrant Hippo YAP/TAZ signaling would be implicated in animal pathologies. Publications on Hippo YAP/TAZ in companion animals are mainly in cats and dogs and related to oncology. Here, we emphasize the important role of YAP/TAZ in liver diseases. First the liver has a remarkable regeneration capacity and a strict size control and the liver has a moderate liver cell renewal (homeostasis). The last years numerous papers show the importance of YAP/TAZ in hepatocellular carcinoma (HCC), hepatocyte differentiation and bile duct epithelial (BEC) cell survival. YAP/TAZ signaling is involved in activation of hepatic stellate cells crucial in fibrogenesis. The availability of drugs (e.g. verteporfin) targeting the YAP/TAZ pathway are described as is their potential usage in veterinary medicine. The aim of this overview is to stimulate researchers' and clinicians' interest in the potential role of Hippo YAP/TAZ signaling in veterinary medicine.

The Hippo Pathway: A Master Regulatory Network Important in Cancer

The Hippo pathway is pervasively activated and has been well recognized to play critical roles in human cancer. The deregulation of Hippo signaling involved in cancer development, progression, and resistance to cancer treatment have been confirmed in several human cancers. Its biological significance and deregulation in cancer have drawn increasing interest in the past few years. A fundamental understanding of the complexity of the Hippo pathway in cancer is crucial for improving future clinical interventions and therapy for cancers. In this review, we try to clarify the complex regulation and function of the Hippo signaling network in cancer development, including its role in signal transduction, metabolic regulation, and tumor development, as well as tumor therapies targeting the Hippo pathway.

Hippo pathway: Regulation, deregulation and potential therapeutic targets in cancer

Hippo pathway is a master regulator of development, cell proliferation, stem cell function, tissue regeneration, homeostasis, and organ size control. Hippo pathway relays signals from different extracellular and intracellular events to regulate cell behavior and functions. Hippo pathway is conserved from Protista to eukaryotes. Deregulation of the Hippo pathway is associated with numerous cancers. Alteration of the Hippo pathway results in cell invasion, migration, disease progression, and therapy resistance in cancers. However, the function of the various components of the mammalian Hippo pathway is yet to be elucidated in detail especially concerning tumor biology. In the present review, we focused on the Hippo pathway in different model organisms, its regulation and deregulation, and possible therapeutic targets for cancer treatment.

Immunotherapy in Treating EGFR-Mutant Lung Cancer: Current Challenges and New Strategies

Lung cancer is the leading cause of cancer-related deaths worldwide. Immune checkpoint inhibitors, including monoclonal antibodies against programmed death-1 (PD-1) and programmed death ligand-1 (PD-L1), have dramatically improved the survival and quality of life of a subset of non-small cell lung cancer (NSCLC) patients. Multiple predictive biomarkers have been proposed to select the patients who may benefit from the immune checkpoint inhibitors. EGFR-mutant NSCLC is the most prevalent molecular subtype in Asian lung cancer patients. However, patients with EGFR-mutant NSCLC show poor response to anti-PD-1/PD-L1 treatment. While small-molecule EGFR tyrosine kinase inhibitors (TKIs) are the preferred initial treatment for EGFR-mutant NSCLC, acquired drug resistance is severely limiting the long-term efficacy. However, there is currently no further effective treatment option for TKIs-refractory EGFR-mutant NSCLC patients. The reasons mediating the poor response of EGFR-mutated NSCLC patients to immunotherapy are not clear. Initial investigations revealed that EGFR-mutated NSCLC has lower PD-L1 expression and a low tumor mutational burden, thus leading to weak immunogenicity. Moreover, the use of PD-1/PD-L1 blockade prior to or concurrent with osimertinib has been reported to increase the risk of pulmonary toxicity. Furthermore, emerging evidence shows that PD-1/PD-L1 blockade in NSCLC patients can lead to hyperprogressive disease associated with dismal prognosis. However, it is difficult to predict the treatment toxicity. New biomarkers are urgently needed to predict response and toxicity associated with the use of PD-1/PD-L1 immunotherapy in EGFR-mutated NSCLC. Recently, promising data have emerged to suggest the potentiation of PD-1/PD-L1 blockade therapy by anti-angiogenic agents and a few other novel therapeutic agents. This article reviews the current investigations about the poor response of EGFR-mutated NSCLC to anti-PD-1/PD-L1 therapy, and discusses the new strategies that may be adopted in the future.

A miR-375/YAP axis regulates neuroendocrine differentiation and tumorigenesis in lung carcinoid cells

Lung carcinoids are variably aggressive and mechanistically understudied neuroendocrine neoplasms (NENs). Here, we identified and elucidated the function of a miR-375/yes-associated protein (YAP) axis in lung carcinoid (H727) cells. miR-375 and YAP are respectively high and low expressed in wild-type H727 cells. Following lentiviral CRISPR/Cas9-mediated miR-375 depletion, we identified distinct transcriptomic changes including dramatic YAP upregulation. We also observed a significant decrease in neuroendocrine differentiation and substantial reductions in cell proliferation, transformation, and tumor growth in cell culture and xenograft mouse disease models. Similarly, YAP overexpression resulted in distinct and partially overlapping transcriptomic changes, phenocopying the effects of miR-375 depletion in the same models as above. Transient YAP knockdown in miR-375-depleted cells reversed the effects of miR-375 on neuroendocrine differentiation and cell proliferation. Pathways analysis and confirmatory real-time PCR studies of shared dysregulated target genes indicate that this axis controls neuroendocrine related functions such as neural differentiation, exocytosis, and secretion. Taken together, we provide compelling evidence that a miR-375/YAP axis is a critical mediator of neuroendocrine differentiation and tumorigenesis in lung carcinoid cells.