YAP1 inhibition radiosensitizes triple negative breast cancer cells by targeting the DNA damage response and cell survival pathways

CYR61 confers chemoresistance by upregulating survivin expression in triple-negative breast cancer

Cysteine-rich angiogenic inducer 61 (CYR61) is a protein from the CCN family of matricellular proteins that play diverse regulatory roles in the extracellular matrix. CYR61 is involved in cell adhesion, migration, proliferation, differentiation, apoptosis, and senescence. Here, we show that CYR61 induces chemoresistance in triple-negative breast cancer (TNBC). We observed that CYR61 is overexpressed in TNBC patients, and CYR61 expression correlates negatively with the survival of patients who receive chemotherapy. CYR61 knockdown reduced cell migration, sphere formation and the cancer stem cell (CSC) population and increased the chemosensitivity of TNBC cells. Mechanistically, CYR61 activated Wnt/β-catenin signaling and increased survivin expression, which are associated with chemoresistance, the epithelial-mesenchymal transition, and CSC-like phenotypes. Altogether, our study demonstrates a novel function of CYR61 in chemotherapy resistance in breast cancer.

Targeting the Hippo pathway to prevent radioresistance brain metastases from the lung (Review)

The prognosis for patients with non‑small cell lung cancer (NSCLC), a cancer type which represents 85% of all lung cancers, is poor with a 5‑year survival rate of 19%, mainly because NSCLC is diagnosed at an advanced and metastatic stage. Despite recent therapeutic advancements, ~50% of patients with NSCLC will develop brain metastases (BMs). Either surgical BM treatment alone for symptomatic patients and patients with single cerebral metastases, or in combination with stereotactic radiotherapy (RT) for patients who are not suitable for surgery or presenting with fewer than four cerebral lesions with a diameter range of 5‑30 mm, or whole‑brain RT for numerous or large BMs can be administered. However, radioresistance (RR) invariably prevents the action of RT. Several mechanisms of RR have been described including hypoxia, cellular stress, presence of cancer stem cells, dysregulation of apoptosis and/or autophagy, dysregulation of the cell cycle, changes in cellular metabolism, epithelial‑to‑mesenchymal transition, overexpression of programmed cell death‑ligand 1 and activation several signaling pathways; however, the role of the Hippo signaling pathway in RR is unclear. Dysregulation of the Hippo pathway in NSCLC confers metastatic properties, and inhibitors targeting this pathway are currently in development. It is therefore essential to evaluate the effect of inhibiting the Hippo pathway, particularly the effector yes‑associated protein‑1, on cerebral metastases originating from lung cancer.

Nuclear phosphoinositide signaling promotes YAP/TAZ-TEAD transcriptional activity in breast cancer

The Hippo pathway effectors Yes-associated protein 1 (YAP) and its homolog TAZ are transcriptional coactivators that control gene expression by binding to TEA domain (TEAD) family transcription factors. The YAP/TAZ-TEAD complex is a key regulator of cancer-specific transcriptional programs, which promote tumor progression in diverse types of cancer, including breast cancer. Despite intensive efforts, the YAP/TAZ-TEAD complex in cancer has remained largely undruggable due to an incomplete mechanistic understanding. Here, we report that nuclear phosphoinositides function as cofactors that mediate the binding of YAP/TAZ to TEADs. The enzymatic products of phosphoinositide kinases PIPKIα and IPMK, including phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) and phosphatidylinositol 3,4,5-trisphosphate (P(I3,4,5)P3), bridge the binding of YAP/TAZ to TEAD. Inhibiting these kinases or the association of YAP/TAZ with PI(4,5)P2 and PI(3,4,5)P3 attenuates YAP/TAZ interaction with the TEADs, the expression of YAP/TAZ target genes, and breast cancer cell motility. Although we could not conclusively exclude the possibility that other enzymatic products of IPMK such as inositol phosphates play a role in the mechanism, our results point to a previously unrecognized role of nuclear phosphoinositide signaling in control of YAP/TAZ activity and implicate this pathway as a potential therapeutic target in YAP/TAZ-driven breast cancer.

Differential Sensitivity to Ionizing Radiation in Gemcitabine-Resistant and Paclitaxel-Resistant Pancreatic Cancer Cells

PURPOSE

Chemoresistance remains a major challenge in treating pancreatic ductal adenocarcinoma (PDAC). Although chemoradiation has proven effective in other tumor types, such as head and neck squamous cell carcinoma, its role in PDAC and effect on acquired chemoresistance have yet to be fully explored. In this study, we investigated the sensitivity of gemcitabine-resistant (GR) and paclitaxel-resistant (PR) PDAC cells to ionizing radiation (IR) and their underlying mechanisms.

METHODS AND MATERIALS

GR and PR clones were generated from PANC-1, PATU-T, and SUIT2-007 pancreatic cancer cell lines. Cell survival after radiation was assessed using clonogenic assay, sulforhodamine B assay, apoptosis, and spheroid growth by bioluminescence. Radiation-induced DNA damage was assessed using Western blot, extra-long polymerase chain reaction, reactive oxygen species production, and immunofluorescence. Autophagy and modulation of the Hippo signaling pathway were investigated using proteomics, Western blot, immunofluorescence, and reverse-transcription quantitative polymerase chain reaction.

RESULTS

In both 2- and 3-dimensional settings, PR cells were more sensitive to IR and showed decreased β-globin amplification, indicating more DNA damage accumulation compared with GR or wild-type cells after 24 hours. Proteomic analysis of PR PATU-T cells revealed that the protein MST4, a kinase involved in autophagy and the Hippo signaling pathway, was highly downregulated. A differential association was found between autophagy and radiation treatment depending on the cell model. Interestingly, increased yes-associated protein nuclear localization and downstream Hippo signaling pathway target gene expression were observed in response to IR.

CONCLUSIONS

This was the first study investigating the potential of IR in targeting PDAC cells with acquired chemoresistance. Our results demonstrate that PR cells exhibit enhanced sensitivity to IR due to greater accumulation of DNA damage. Additionally, depending on the specific cellular context, radiation-induced modulation of autophagy and the Hippo signaling pathway emerged as potential underlying mechanisms, findings with potential to inform personalized treatment strategies for patients with acquired chemoresistance.

Modern Stereotactic Radiotherapy for Brain Metastases from Lung Cancer: Current Trends and Future Perspectives Based on Integrated Translational Approaches

Brain metastases (BMs) represent the most frequent metastatic event in the course of lung cancer patients, occurring in approximately 50% of patients with non-small-cell lung cancer (NSCLC) and in up to 70% in patients with small-cell lung cancer (SCLC). Thus far, many advances have been made in the diagnostic and therapeutic procedures, allowing improvements in the prognosis of these patients. The modern approach relies on the integration of several factors, such as accurate histological and molecular profiling, comprehensive assessment of clinical parameters and precise definition of the extent of intracranial and extracranial disease involvement. The combination of these factors is pivotal to guide the multidisciplinary discussion and to offer the most appropriate treatment to these patients based on a personalized approach. Focal radiotherapy (RT), in all its modalities (radiosurgery (SRS), fractionated stereotactic radiotherapy (SRT), adjuvant stereotactic radiotherapy (aSRT)), is the cornerstone of BM management, either alone or in combination with surgery and systemic therapies. We review the modern therapeutic strategies available to treat lung cancer patients with brain involvement. This includes an accurate review of the different technical solutions which can be exploited to provide a "state-of-art" focal RT and also a detailed description of the systemic agents available as effective alternatives to SRS/SRT when a targetable molecular driver is present. In addition to the validated treatment options, we also discuss the future perspective for focal RT, based on emerging clinical reports (e.g., SRS for patients with many BMs from NSCLC or SRS for BMs from SCLC), together with a presentation of innovative and promising findings in translational research and the combination of novel targeted agents with SRS/SRT.

Yes-Associated Protein 1 Inhibition Induces Immunogenic Cell Death and Synergizes With Radiation and PD-1 Blockade

PURPOSE

Danger signals released by ionizing radiation (IR) can theoretically stimulate immune activation in the tumor environment (TME), but IR alone is not sufficient to induce an effective immune response in clinical practice. In this study, we investigated whether inhibition of yes-associated protein 1 (YAP1) could induce immunogenic cell death (ICD) and whether the combination of YAP1 inhibition with IR could increase in vivo immune infiltration and thereby boost a tumor response to immunotherapy.

METHODS AND MATERIALS

First, the expression of ICD markers, markers of T-cell activation, and key proteins involved in innate immune signaling were measured after YAP1 inhibition. Next, the expression level of YAP1 protein was measured after different doses of IR. Then, the antitumor effect of YAP1 inhibition combined with IR was investigated in vivo, and the immune status of the TME was evaluated. Finally, the efficacy of a triple therapy including YAP1 inhibition combined with IR and programmed cell death protein 1 blockade in the treatment of resistant tumors was determined.

RESULTS

We found that YAP1 inhibition induced ICD and increased the levels of antigen presentation machinery, effectively causing the activation of T cells. Mechanistically, YAP1 inhibition induced cell DNA damage and activated the cyclic GMP-AMP synthase (cGAS)/stimulator of interferon genes (STING) pathway. Surprisingly, IR upregulated YAP1 expression. IR combined with YAP1 inhibition significantly inhibited cancer growth and prolonged survival, which was related to the augmented infiltration, activation, and function of CD8+ T cells in the TME. Moreover, the addition of YAP1 inhibition significantly improved the efficacy of pancreatic cancer treatment when neither radiation nor programmed cell death protein 1 inhibitors were ideal.

CONCLUSIONS

YAP1 inhibition could trigger ICD and is a potential approach to potentiating the therapeutic efficacy of radiation therapy and anti-PD1 immunotherapy.

Reduced YAP1 and FOLR1 in gliomas predict better response to chemotherapeutics

Gliomas harbouring mutations in IDH1 (isocitrate dehydrogenase 1) are characterized by greater sensitivity to chemotherapeutics. These mutants also exhibit diminished levels of transcriptional coactivator YAP1 (yes-associated protein 1). Enhanced DNA damage in IDH1 mutant cells, as evidenced by γH2AX formation (phosphorylation of histone variant H2A.X) and ATM (serine/threonine kinase; ataxia telangiectasia mutated) phosphorylation, was accompanied by reduced FOLR1 (folate receptor 1) expression. Diminished FOLR1, concomitant with heightened γH2AX levels, was also observed in patient-derived IDH1 mutant glioma tissues. Chromatin immunoprecipitation, overexpression of mutant YAP1, and treatment with YAP1-TEAD (TEA domain transcription factors) complex inhibitor verteporfin demonstrated regulation of FOLR1 expression by YAP1 and its partner transcription factor TEAD2. TCGA (The Cancer Genome Atlas) data analysis demonstrated better patient survival with reduced FOLR1 expression. Depletion of FOLR1 rendered IDH1 wild-type gliomas more susceptible to temozolomide-mediated death. Despite heightened DNA damage, IDH1 mutants exhibited reduced levels of IL6 (interleukin 6) and IL8 (interleukin 8) - pro-inflammatory cytokines known to be associated with persistent DNA damage. While both FOLR1 and YAP1 influenced DNA damage, only YAP1 was involved in regulating IL6 and IL8. ESTIMATE and CIBERSORTx analyses revealed the association between YAP1 expression and immune cell infiltration in gliomas. By identifying the influence of YAP1-FOLR1 link in DNA damage, our findings suggest that simultaneous depletion of both could amplify the potency of DNA damaging agents, while concomitantly reducing the release of inflammatory mediators and potentially affecting immune modulation. This study also highlights the novel role of FOLR1 as a probable prognostic marker in gliomas, predicting responsiveness to temozolomide and other DNA damaging agents.

Hypoxia-induced YAP activation and focal adhesion turnover to promote cell migration in mesenchymal TNBC cells

BACKGROUND

Hypoxia is commonly characterized by malignant tumors that promote the aggressiveness and metastatic potential of cancer. Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer, with approximately 46% capacity related to distant metastasis. Transcriptional factor yes-associated protein (YAP), a core component of the Hippo pathway, is associated with poor prognosis and outcome in cancer metastasis. Here, we explored the effect of hypoxia-mediated YAP activation and focal adhesions (FAs) turnover in mesenchymal TNBC cell migration.

METHODS

We characterized the effect of hypoxia on YAP in different breast cancer cell lines using a hypoxia chamber and CoCl₂ .

RESULTS

Hypoxia-induced YAP nuclear translocation is significantly observed in normal breast epithelial cells, non-TNBC cells, mesenchymal TNBC cells, but not in basal-like TNBC cells. Functionally, we demonstrated that YAP activation was required for hypoxia to promote mesenchymal TNBC cell migration. Furthermore, hypoxia induced the localization of FAs at the leading edge of mesenchymal TNBC cells. In contrast, verteporfin (VP), a YAP inhibitor, significantly reduced the migration and the recruitment of nascent FAs at the cell periphery under hypoxia conditions, which only showed in mesenchymal TNBC cells.

CONCLUSIONS

Our data support the hypothesis that YAP is novel factor and positively responsible for hypoxia-promoting mesenchymal TNBC cell migration. Our findings provide further evidence and outcomes to help prevent the progression of TNBC.

Effect of mechanical forces on cellular response to radiation

While the cellular interactions and biochemical signaling has been investigated for long and showed to play a major role in the cell's fate, it is now also evident that mechanical forces continuously applied to the cells in their microenvironment are as important for tissue homeostasis. Mechanical cues are emerging as key regulators of cellular drug response and we aimed to demonstrate in this review that such effects should also be considered vital for the cellular response to radiation. In order to explore the mechanobiology of the radiation response, we reviewed the main mechanoreceptors and transducers, including integrin-mediated adhesion, YAP/TAZ pathways, Wnt/β-catenin signaling, ion channels and G protein-coupled receptors and showed their implication in the modulation of cellular radiosensitivity. We then discussed the current studies that investigated a direct effect of mechanical stress, including extracellular matrix stiffness, shear stress and mechanical strain, on radiation response of cancer and normal cells and showed through preliminary results that such stress effectively can alter cell response after irradiation. However, we also highlighted the limitations of these studies and emphasized some of the contradictory data, demonstrating that the effect of mechanical cues could involve complex interactions and potential crosstalk with numerous cellular processes also affected by irradiation. Overall, mechanical forces alter radiation response and although additional studies are required to deeply understand the underlying mechanisms, these effects should not be neglected in radiation research as they could reveal new fundamental knowledge for predicting radiosensitivity or understanding resistance to radiotherapy.

Radiation therapy affects YAP expression and intracellular localization by modulating lamin A/C levels in breast cancer

The microenvironment of breast cancer actively participates in tumorigenesis and cancer progression. The changes observed in the architecture of the extracellular matrix initiate an oncogene-mediated cell reprogramming, that leads to a massive triggering of YAP nuclear entry, and, therefore, to cancer cell proliferation, invasion and probably to increased radiation-resistance. However, it is not yet fully understood how radiotherapy regulates the expression and subcellular localization of YAP in breast cancer cells experiencing different microenvironmental stiffnesses. To elucidate the role of extracellular matrix stiffness and ionizing radiations on YAP regulation, we explored the behaviour of two different mammary cell lines, a normal epithelial cell line (MCF10A) and a highly aggressive and invasive adenocarcinoma cell line (MDA-MB-231) interacting with polyacrylamide substrates mimicking the mechanics of both normal and tumour tissues (∼1 and ∼13 kPa). We report that X-ray radiation affected in a significant way the levels of YAP expression, density, and localization in both cell lines. After 24 h, MCF10A and MDA-MB-231 increased the expression level of YAP in both nucleus and cytoplasm in a dose dependent manner and particularly on the stiffer substrates. After 72 h, MCF10A reduced mostly the YAP expression in the cytoplasm, whereas it remained high in the nucleus of cells on stiffer substrates. Tumour cells continued to exhibit higher levels of YAP expression, especially in the cytoplasmic compartment, as indicated by the reduction of nuclear/cytoplasmic ratio of total YAP. Then, we investigated the existence of a correlation between YAP localization and the expression of the nuclear envelope protein lamin A/C, considering its key role in modulating nuclear deformability and changes in YAP shuttling phenomena. As supposed, we found that the effects of radiation on YAP nucleus/cytoplasmic expression ratio, increasing in healthy cells and decreasing in tumour ones, were accompanied by lower and higher lamin A/C levels in MCF10A and MDA-MB-231 cells, respectively. These findings point to obtain a deeper knowledge of the role of the extracellular matrix and the effects of X-rays on YAP and lamin A/C expression that can be used in the design of doses and timing of radiation therapy.

Relationship between Yes-Associated Protein 1 and Prognosis of Digestive System Neoplasm: Quantitative Analysis and Bioinformatics Analysis Based on 4023 Patients

Yes-associated protein 1 (YAP1) is involved in the development of a variety of malignancies. However, the prognosis of malignant digestive tumors with YAP1 expression is still controversial. This study searched 31 articles with 36 data sets of 4023 patients to explore the role of YAP1 expression on the prognosis of digestive malignant tumors by searching the PubMed, Embase, Web of Science, Google Scholar, and Cochrane Library databases. Specifically, relevant cancer expression matrix data were downloaded from The Cancer Genome Atlas (TCGA) database. In this meta-analysis, quantitative analysis showed that the overexpression of YAP1 was not conducive to OS (1.62, 95% CI (1.38, 1.90), P=0.001) and DFS (1.59, 95% CI (1.31, 1.93), P=0.001) in patients with digestive malignant tumors. In addition, TCGA database analysis showed that YAP1 was overexpressed in gastric cancer, cholangiocarcinoma, and colorectal cancer. Survival analysis showed that the patients with high expression of YAP1 in pancreatic cancer have a poor OS (MST: 394 vs. 691 days, P < 0.0001) and DFS (MST: 371 vs. 542 days, P=0.026) prognosis. YAP1 may be a molecular marker that effectively predicts the survival of malignant digestive tumors, especially pancreatic cancer, and is a potential therapeutic target for malignant digestive tumors.

ANKHD1 contributes to the malignant phenotype of triple-negative breast cancer cells

Ankyrin repeat and KH domain-containing protein 1, ANKHD1, has been identified as a regulator of signaling pathways and cellular processes of relevance in carcinogenesis. However, the role of ANKHD1 in breast cancer remains unclear. The aim of the present study was to characterize the expression pattern and involvement of ANKHD1 in the malignant phenotype of breast cancer cell lines and to investigate the clinical relevance of ANKHD1 in a breast cancer context. Gene and protein expressions were assessed in the cell lines by quantitative reverse transcription PCR and Western blot analysis, respectively, and ANKHD1 silencing through siRNA transfection was conducted for further in vitro functional assays. The expression of ANKHD1 was identified in non-tumorigenic breast epithelium and breast cancer cell lines, but differences in cellular localization were found among the neoplasia subtypes. ANKHD1 silencing reduced the viability, clonogenicity, and migration of triple-negative breast cancer (TNBC) cells. Bioinformatics analyses demonstrated that patients with triple-negative basal-like 2 and mesenchymal breast cancer subtypes had high ANKHD1 expression associated with poor recurrence-free survival. Therefore, these data indicate that ANKHD1 relevance in breast cancer varies among its subtypes, indicating the importance of ANKHD1 in TNBC.

Analysis of Yes-Associated Protein-1 (YAP1) Target Gene Signature to Predict Progressive Breast Cancer

Breast cancers are treated according to the ER/PR or HER2 expression and show better survival outcomes with targeted therapy. Triple-negative breast cancers (TNBCs) with a lack of expression of ER/PR and HER2 are treated with systemic therapy with unpredictable responses and outcomes. It is essential to investigate novel markers to identify targeted therapies for TNBC. One such marker is YAP1, a transcription co-activator protein that shows association with poor prognosis of breast cancer. YAP1 transcriptionally regulates the expression of genes that drive the oncogenic phenotypes. Here, we assess a potential YAP target gene signature to predict a progressive subset of breast tumors from METABRIC and TCGA datasets. YAP1 target genes were shortlisted based on expression correlation and concordance with YAP1 expression and significant association with survival outcomes of patients. Hierarchical clustering was performed for the shortlisted genes. The utility of the clustered genes was assessed by survival analysis to identify a recurring subset. Expression of the shortlisted target genes showed significant association with survival outcomes of HER2-positive and TNBC subset in both datasets. The shortlisted genes were verified using an independent dataset. Further validation using IHC can prove the utility of this potential prognostic signature to identify a recurrent subset of HER2-positive and TNBC subtypes.

Exosomal-microRNA transcriptome profiling of Parental and CSC-like MDA-MB-231 cells in response to cisplatin treatment

Triple negative breast cancer (TNBC) is the most aggressive breast cancer subtype with higher risk of metastasis and cancer reoccurrence. Cisplatin is one of the potential anticancer drugs for treating TNBC, where its effectiveness remains challenged by frequent occurrence of cisplatin resistance. Since acquirement of drug resistance often being associated with presence of cancer stem cells (CSCs), investigation has been conducted, suggesting CSC-like subpopulation to be more resistant to cisplatin than their parental counterpart. On the other hand, plethora evidences showed the transmission of exosomal-miRNAs are capable of promoting drug resistance in breast cancers. In this study, we aim to elucidate the differential expression of exosomal-microRNAs profile and reveal the potential target genes in correlation to cisplatin resistance associated with CSC-like subpopulation by using TNBC cell line (MDA-MB-231). Utilizing next generation sequencing and Nanostring techniques, cisplatin-induced dysregulation of exosomal-miRNAs were evaluated in maximal for CSC-like subpopulation as compared to parental cells. Intriguingly, more oncogenic exosomal-miRNAs profile was detected from treated CSC-like subpopulation, which may correlate to enhancement of drug resistance and maintenance of CSCs. In treated CSC-like subpopulation, unique clusters of exosomal-miRNAs namely miR-221-3p, miR-196a-5p, miR-17-5p and miR-126-3p were predicted to target on six genes (ATXN1, LATS1, GSK3β, ITGA6, JAG1 and MYC), aligned with previous finding which demonstrated dysregulation of these genes in treated CSC-like subpopulation. Our results highlight the potential correlation of exosomal-miRNAs and their target genes as well as novel perspectives of the corresponding pathways that may be essential to contribute to the attenuated cytotoxicity of cisplatin in CSC-like subpopulation.

The Hippo pathway effectors YAP and TAZ interact with EGF-like signaling to regulate expansion-related events in bovine cumulus cells in vitro

PURPOSE

To determine if the inhibition of the interaction between the Hippo effector YAP or its transcriptional co-activator TAZ with the TEAD family of transcription factors is critical for the cumulus expansion-related events induced by the EGF network in cumulus-oocyte complexes (COCs).

METHODS

We performed a series of experiments using immature bovine COCs subjected to an IVM protocol for up 24 h in which cumulus expansion was stimulated with EGF recombinant protein or FSH.

RESULTS

The main results indicated that EGFR activity stimulation in bovine cumulus cells (CC) increases mRNA levels encoding the classic YAP/TAZ-TEAD target gene CTGF. To determine if important genes for cumulus expansion are transcriptional targets of YAP/TAZ-TEAD interaction in CC, COCs were then subjected to IVM in the presence of FSH with or without distinct concentrations of Verteporfin (VP; a small molecule inhibitor that interferes with YAP/TAZ binding to TEADs). COCs were then collected at 6, 12, 18, and 24 h for total RNA extraction and RT-qPCR analyses. This experiment indicated that VP inhibits in a time- and concentration-dependent manner distinct cumulus expansion and oocyte maturation-related genes, by regulating EGFR and CTGF expression in CC.

CONCLUSIONS

Taken together, the results presented herein represent considerable insight into the functional relevance of a completely novel signaling pathway underlying cumulus expansion and oocyte maturation in monovulatory species. YAP/TAZ or CTGF may represent potential targets to improve the efficiency of IVM systems, not only for monovulatory species of agricultural importance as the cow, but for human embryo production.

An innovative targeted therapy for fluoroscopy-induced chronic radiation dermatitis

Fluoroscopy-induced chronic radiation dermatitis (FICRD) is a complication of fluoroscopy-guided intervention. Unlike acute radiation dermatitis, FICRD is different as delayed onset and usually appears without preexisting acute dermatitis. Unfortunately, the chronic and progressive pathology of FICRD makes it difficult to treat, and some patients need to receive wide excision and reconstruction surgery. Due to lack of standard treatment, investigating underlying mechanism is needed in order to develop an effective therapy. Herein, the Hippo pathway is specifically identified using an RNA-seq analysis in mild damaged skin specimens of patients with FICRD. Furthermore, specific increase of the Yes-associated protein (YAP1), an effector of the Hippo pathway, in skin region with mild damage plays a protective role for keratinocytes via positively regulating the numerous downstream genes involved in different biological processes. Interestingly, irradiated-keratinocytes inhibit activation of fibroblasts under TGF-β1 treatment via remote control by an exosome containing YAP1. More importantly, targeting one of YAP1 downstream genes, nuclear receptor subfamily 3 group C member 1 (NR3C1), which encodes glucocorticoid receptor, has revealed its therapeutic potential to treat FICRD by inhibiting fibroblasts activation in vitro and preventing formation of radiation ulcers in a mouse model and in patients with FICRD. Taken together, this translational research demonstrates the critical role of YAP1 in FICRD and identification of a feasible, effective therapy for patients with FICRD. KEY MESSAGES: • YAP1 overexpression in skin specimens of radiation dermatitis from FICRD patient. • Radiation-induced YAP1 expression plays protective roles by promoting DNA damage repair and inhibiting fibrosis via remote control of exosomal YAP1. • YAP1 positively regulates NR3C1 which encodes glucocorticoid receptor expression. • Targeting glucocorticoid receptor by prednisolone has therapeutic potential for FICRD patient.

Long Noncoding-RNA Component of Mitochondrial RNA Processing Endoribonuclease Promotes Carcinogenesis in Triple-Negative Breast Cancer Cells via the Competing Endogenous RNA Mechanism

Purpose

Triple-negative breast cancer (TNBC) is a subtype of breast cancer. Increasing evidence supports that dysregulation of long noncoding RNAs (lncRNAs) plays a vital role in cancer progression. RNA component of mitochondrial RNA processing endoribonuclease (RMRP), a lncRNA, is characterized as a tumor-propeller in some cancers, but its mechanism in TNBC remains poorly understood. This study aimed to determine whether and how RMRP functions in TNBC.

Methods

Cell proliferation was determined by cell counting kit-8 (CCK-8) and colony formation assays and cell apoptosis by flow cytometry analysis and terminal deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) assay. Cell migration and invasion were determined by transwell assays. RNA-binding protein immunoprecipitation (RIP), luciferase reporter, and RNA pulldown assays were implemented to assess the interaction of RMRP with other molecules in TNBC cells.

Results

RMRP expression was elevated in TNBC cells. RMRP knockdown repressed cell proliferation, migration, and invasion, but induced apoptosis in TNBC. In addition, RMRP was found to target microRNA-766-5p (miR-766-5p) in TNBC cells. Silencing miR-766-5p enhanced cell viability and decreased apoptosis, whereas miR-766-5p overexpression had opposite effects. Furthermore, miR-766-5p was found to bind to yes-associated protein 1 (YAP1). Moreover, miR-766-5p inhibition reversed the repressive effect of RMRP knockdown on the malignant progression of TNBC.

Conclusion

The present study manifested that RMRP promotes the growth, migration, and invasion of TNBC cells via the miR-766-5p/YAP1 axis. These findings provide novel perspectives for TNBC treatment.

Verteporfin suppresses osteosarcoma progression by targeting the Hippo signaling pathway

Verteporfin (VP) is a specific inhibitor of yes-associated protein 1 (YAP1) that suppresses tumor progression by inhibiting YAP1 expression. The present study aimed to determine the inhibitory effect of VP on osteosarcoma and the underlying mechanism of its anticancer effects. Cell viability, cell cycle and apoptosis and cell migration and invasion were analyzed using the MTT assay, flow cytometry, wound healing assay and Transwell assay, respectively. Expressions of YAP1 and TEA domain transcription factor 1 (TEAD1) were measured using reverse transcription-quantitative PCR and western blotting, while their interaction was identified by the co-immunoprecipitation assay. In vivo mouse xenograft experiments were performed to evaluate the effect of VP on osteosarcoma growth. The results demonstrated that YAP1 and TEAD1 were highly expressed in osteosarcoma cells and tissues, whereas VP significantly downregulated the expression levels of YAP1 and TEAD1 in the osteosarcoma cell line Saos-2 compared with those in untreated control cells. In addition, compared with those in the control group, VP suppressed the viability, migration and invasion, induced cell cycle arrest in the G1 phase and promoted apoptosis in Saos-2 cells. In addition, VP inhibited mouse xenograft tumor growth in vivo compared with that observed in the control group. Notably, VP downregulated the levels of CYR61 expression in Saos-2 cells, whereas CYR61 overexpression mitigated the inhibitory effects of VP on osteosarcoma cells, as indicated by the increased viability and reduced apoptotic rates in Saos-2 cells overexpressing CYR61 compared with those in the control group. In summary, VP suppressed osteosarcoma by downregulating the expression of YAP1 and TEAD1. Additionally, CYR61 may mediate the effects of VP on osteosarcoma progression.

An insight into the cancer stem cell survival pathways involved in chemoresistance in triple-negative breast cancer

Triple-negative breast cancer (TNBC) is the most complex, aggressive and fatal subtype of breast cancer. Owing to the lack of targeted therapy and heterogenic nature of TNBC, chemotherapy remains the sole treatment option for TNBC, with taxanes and anthracyclines representing the general chemotherapeutic regimen in TNBC therapy. But unfortunately, patients develop resistance to the existing chemotherapeutic regimen, resulting in approximately 90% treatment failure. Breast cancer stem cells (BCSCs) are one of the major causes for the development of chemoresistance in TNBC patients. After surviving the chemotherapy damage, the presence of BCSCs results in relapse and recurrence of TNBC. Several pathways are known to regulate BCSCs' survival, such as the Wnt/β-catenin, Hedgehog, JAK/STAT and HIPPO pathways. Therefore it is imperative to target these pathways in the context of eliminating chemoresistance. In this review we will discuss the novel strategies and various preclinical and clinical studies to give an insight into overcoming TNBC chemoresistance. We present a detailed account of recent studies carried out that open an exciting perspective in relation to the mechanisms of chemoresistance.

Clinical significance of YAP1 and TAZ in esophageal squamous cell carcinoma

BACKGROUND

Esophageal cancer is the eighth most frequent and sixth most fatal cancer worldwide. This study aimed to investigate the clinical characteristics and prognostic significance of yes related protein 1 (YAP1) and transcriptional co-activator with PDZ binding motif (TAZ) in patients with esophageal squamous cell carcinoma (ESCC).

METHODS

A total of 306 ESCC pathological specimens and adjacent tissues (as control; tissues from the esophageal mucosa >5 cm from the edge of the tumor) were collected between January, 2008 and December, 2018. Immunohistochemical staining was used to assess the expression of YAP1 and TAZ proteins in the ESCC and adjacent tissues, and their relationship with clinicopathological parameters was evaluated using SPSS 21.0 software.

RESULTS

YAP1 and TAZ proteins were highly expressed in ESCC, and their expression was closely related to TNM stage and lymph node metastasis. Expression of YAP1 was associated with tumor size (P = .029), differentiation (P = .000), depth of invasion (P = .001), and TNM stage (P = .000). Expression of TAZ was associated with tumor size (P = .034), differentiation (P = .000), depth of invasion (P = .029), lymph node metastasis (P = .006), and ethnicity (P < .001). The expression of YAP1 protein was positively correlated with the expression of TAZ protein (r = 0.257, P < .05). YAP1 and TAZ expression (P = .039 and .000, respectively), tumor size (P = .041), and lymph node metastasis (P = .001) significantly affected the overall survival of patients with ESCC, and represent independent factors for overall survival.

CONCLUSION

YAP1 and TAZ proteins are highly expressed in ESCC, and closely related to the clinical and pathological parameters such as the diameter of the tumor, degree of differentiation, and depth of invasion, indicating that YAP1 and TAZ may be involved in the development of ESCC. YAP1 and TAZ may be used as prognostic markers in ESCC.

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.

miR-497 inhibits proliferation and invasion in triple-negative breast cancer cells via YAP1

MicroRNA (miR)-497 has been reported as a tumor suppressor in various cancer types. Nonetheless, the regulation of triple-negative breast cancer (TNBC) by miR-497 remains poorly understood. The present study aimed to investigate the potential function and mechanism of miR-497 in TNBC. A total of 36 TNBC and matched non-cancerous tissue samples were collected for analysis. Reverse transcription-quantitative PCR was performed to detect the miR-497 levels in TNBC tissue. The association between miR-497 expression, clinical characteristics and survival was then analyzed. To investigate the role of miR-497 in TNBC, MTT, colony formation, Transwell invasion, cell cycle and cell apoptosis assays were conducted following transfection of miR-497 mimics into the MDA-MB-231 and MDA-MB-468 cell lines. Luciferase reporter assays and western blot analysis were used to confirm the regulation of a putative target of miR-497. The results indicated that the expression of miR-497 was downregulated in the TNBC specimens. Further analysis demonstrated that the expression of miR-497 was downregulated in patients with advanced TNBC stages and that low miR-497 was associated with poor prognosis in patients with TNBC. Transfection of miR-497 mimics inhibited TNBC cell proliferation and increased cell apoptosis in MDA-MB-231 and MDA-MB-468 cells. Moreover, cell migration was inhibited following overexpression of miR-497, which also led to the arrest of the breast cancer cells in the G₀/G₁ phase of the cell cycle. Yes-associated protein 1 (YAP1), a critical molecule in the Hippo pathway, was identified as a target of miR-497. Notably, the protein and mRNA expression levels of YAP1 in MDA-MB-231 and MDA-MB-468 cells were downregulated following overexpression of miR-497. Overall, the findings of the present study indicated that miR-497 inhibited TNBC cell proliferation and migration and induced cell apoptosis by negatively regulating YAP1 expression. Thus, targeting miR-497 may represent a potential strategy for the treatment of TNBC.

Increased YAP1 expression is significantly associated with breast cancer progression, metastasis and poor survival

YAP1 plays a key role as a transcriptional coactivator in the Hippo pathway. Based on conflicting reports regarding YAP1 function in cancer, this study discerned its role in breast carcinogenesis. First, a systematic review of salient breast cancer studies targeting YAP1 dysregulation was performed. Additionally, freshly excised tumor specimens of approximately 200 breast cancer patients were processed for quantification of YAP1 expression at mRNA and protein levels using quantitative PCR and immunohistochemistry, respectively. YAP1 expression was nine folds higher in tumors versus controls and significantly associated with metastasis (p < 0.05) and poor survival in Pakistani breast cancer patients. These findings establish the role of YAP1 overexpression in tumorigenesis and metastasis. Hence, YAP1 inhibition may be considered a possible therapeutic strategy.

Local Treatment of Triple-Negative Breast Cancer

ABSTRACT

Triple-negative breast cancer, compared with other molecular subtypes, poses particular challenges for optimizing the timing and the extent of locoregional treatments. In the past, the combination of increased rates of both locoregional and distant recurrences led to a preference of radical surgery and extensive radiation therapy; however, since the introduction of more effective chemotherapy, a sharp de-escalation in the extent of locoregional treatments followed. Current evidence confirms that less aggressive surgery in combination with tailored radiation therapy offers improved oncological outcomes combined with better quality of life. However, further research is required to optimize locoregional treatments, considering the significant heterogeneity in biological behavior and tumor response to systemic treatments.

Targeting Yes1 Associated Transcriptional Regulator Inhibits Hepatocellular Carcinoma Progression and Improves Sensitivity to Sorafenib: An in vitro and in vivo Study

Purpose

The aim of this study was to investigate the role of Yes1 associated transcriptional regulator (YAP1) in the pathology of hepatocellular carcinoma (HCC) and its potential as a therapeutic target.

Methods

YAP1 expression in HCC and adjacent tissues was determined via immunohistochemistry; in HCC and human normal liver cell lines, expression was examined via Western blotting. The effects of YAP1 knockdown and overexpression were detected following transfection of HCC cells with siRNA-YAP1 recombinants or pcDNA3.1-YAP1 plasmids. A tumor xenograft model was constructed by implanting YAP1-knockdown lentivirus-infected Hep-3B cells into nude mice, and the animals were treated with sorafenib.

Results

In patients with HCC, YAP1 was upregulated in tumor tissue compared with adjacent tissue, and its high expression in the tumor was associated with increased Edmonson grade. In vitro, YAP1 expression was increased in Hep-3B, SK-HEP-1 and Huh7 cells, while it was similar in SMMC-7721 cells and LO2 cells. Meanwhile, YAP1 increased cell proliferation and invasion, promoted the progression of epithelial-mesenchymal transition, and inhibited cell apoptosis in HCC cells; furthermore, YAP1 knockdown combined with the administration of sorafenib decreased cell viability and increased cell apoptosis compared with YAP1 knockdown or treatment with sorafenib alone. In vivo, YAP1 knockdown inhibited tumor growth and metastasis, whereas it promoted apoptosis; meanwhile, YAP1 knockdown synergized with sorafenib to suppress tumor progression in HCC mice.

Conclusion

YAP1 is upregulated in both HCC tumor tissues and cell lines. Moreover, it promotes cell proliferation and invasion and promoted the progression of epithelial-mesenchymal transition in vitro. Furthermore, targeting YAP1 inhibits HCC progression and improves sensitivity to sorafenib in vitro and in vivo.

Clinicopathologic significance of nuclear HER4 and phospho-YAP(S127) in human breast cancers and matching brain metastases

Background

Human epidermal growth factor receptor-4 (HER4) and yes-associated protein-1 (YAP) are candidate therapeutic targets in oncology. YAP's transcriptional coactivation function is modulated by the HER4 intracellular domain (HER4-ICD) in vitro, but the clinical relevance of this has not been established. This study investigated the potential for targeting the HER4-YAP pathway in brain metastatic breast cancer.

Methods

We performed immuno-phenotypic profiling of pathway markers in a consecutive breast cancer series with 25 years of clinical follow up (n = 371), and patient-matched breast and metastatic brain tumours (n = 91; 30 pairs).

Results

Membrane localisation of phospho-HER4 [pHER4(Y¹¹⁶²)] was infrequent in primary breast cancer, but very frequent in brain metastases (5.9% versus 75% positive), where it was usually co-expressed with pHER3(Y¹²⁸⁹) (p < 0.05). The presence of YAP in tumour cell nuclei was associated directly with nuclear pERK5(T²¹⁸/Y²¹⁰) (p = 0.003). However, relationships with disease-specific survival depended on oestrogen receptor (ER) status. Nuclear pYAP(S¹²⁷) was associated with smaller, good prognostic ER+ breast tumours (log-rank hazard-ratio 0.53; p = 9.6E^-03), but larger, poor prognostic triple-negative cancers (log-rank hazard-ratio 2.78; p = 1.7E^-02), particularly when co-expressed with nuclear HER4-ICD (p = 0.02). This phenotype was associated with stemness and mitotic instability markers (vimentin, SOX9, ID1, SPAG5, TTK, geminin; p < 0.05). YAP expression in brain metastases was higher than matched primary tumours; specifically, nuclear pYAP(S¹²⁷) in ER-negative cases (p < 0.05). Nuclear YAP was detected in ~70% of ER-negative, HER4-activated brain metastases.

Discussion

Our findings suggest that the canonical-mechanism where Hippo pathway-mediated phosphorylation of YAP ostensibly excludes it from the nucleus is dysfunctional in breast cancer. The data are consistent with pYAP(S¹²⁷) having independent transcriptional functions, which may include transducing neuregulin signals in brain metastases. Consistent with mechanistic studies implicating it as an ER co-factor, nuclear pYAP(S¹²⁷) associations with breast cancer clinical outcomes were dependent on ER status.

Conclusion

Preclinical studies investigating HER4 and nuclear YAP combination therapy strategies are warranted.

The Role of the Hippo Pathway in Breast Cancer Carcinogenesis, Prognosis, and Treatment: A Systematic Review

Background

The Hippo pathway is a developmental pathway recently discovered in Drosophila melanogaster; in mammals it normally controls organ development and wound healing. Hippo signaling is deregulated in breast cancer (BC). MST1/2 and LATS1/2 kinases are the upstream molecular elements of Hippo signaling which phosphorylate and regulate the two effectors of Hippo signaling, YAP1 and TAZ cotranscriptional activators. The two molecular effectors of the Hippo pathway facilitate their activity through TEAD transcription factors. Several molecular pathways with known oncogenic functions cross-talk with the Hippo pathway.

Methods

A systematic review studying the correlation of the Hippo pathway with BC tumorigenesis, prognosis, and treatment was performed.

Results

Recent literature highlights the critical role of Hippo signaling in a wide spectrum of biological mechanisms in BC.

Discussion

The Hippo pathway has a crucial position in BC molecular biology, cellular behavior, and response to treatment. Targeting the Hippo pathway could potentially improve the prognosis and outcome of BC patients.

IGF-1/IGF-1R/FAK/YAP Transduction Signaling Prompts Growth Effects in Triple-Negative Breast Cancer (TNBC) Cells

Triple-negative breast cancer (TNBC) is an aggressive breast tumor subtype that currently lacks targeted treatment options. The role played by the insulin-like growth factor-1 (IGF-1) and its cognate receptor IGF-1R in TNBC has been reported. Nevertheless, the molecular mechanisms by which the IGF-1/IGF-1R system may contribute to TNBC progression still remains to be fully understood. By computational analysis of the vast cancer genomics information in public databases (TCGA and METABRIC), we obtained evidence that high IGF-1 or IGF-1R levels correlate with a worse clinical outcome in TNBC patients. Further bioinformatics analysis revealed that both the focal adhesion and the Hippo pathways are enriched in TNBC harboring an elevated expression of IGF-1 or IGF-1R. Mechanistically, we found that in TNBC cells, the IGF-1/IGF-1R system promotes the activation of the FAK signal transduction pathway, which in turn regulates the nuclear accumulation of YAP (yes-associated protein/yes-related protein) and the expression of its target genes. At the biological level, we found that the IGF-1/IGF-1R-FAK-YAP network cascade triggers the growth potential of TNBC cells, as evaluated in different experimental systems. Overall, our results suggest that the IGF-1/IGF-1R/FAK/YAP axis may contribute to the progression of the aggressive TNBC subtype.

RASSF1A Tumour Suppressor: Target the Network for Effective Cancer Therapy

The RASSF1A tumour suppressor is a scaffold protein that is involved in cell signalling. Increasing evidence shows that this protein sits at the crossroad of a complex signalling network, which includes key regulators of cellular homeostasis, such as Ras, MST2/Hippo, p53, and death receptor pathways. The loss of expression of RASSF1A is one of the most common events in solid tumours and is usually caused by gene silencing through DNA methylation. Thus, re-expression of RASSF1A or therapeutic targeting of effector modules of its complex signalling network, is a promising avenue for treating several tumour types. Here, we review the main modules of the RASSF1A signalling network and the evidence for the effects of network deregulation in different cancer types. In particular, we summarise the epigenetic mechanism that mediates RASSF1A promoter methylation and the Hippo and RAF1 signalling modules. Finally, we discuss different strategies that are described for re-establishing RASSF1A function and how a multitargeting pathway approach selecting druggable nodes in this network could lead to new cancer treatments.

Phytochemicals inhibit migration of triple negative breast cancer cells by targeting kinase signaling

BACKGROUND

Cell migration and invasion are essential processes for metastatic dissemination of cancer cells. Significant progress has been made in developing new therapies against oncogenic signaling to eliminate cancer cells and shrink tumors. However, inherent heterogeneity and treatment-induced adaptation to drugs commonly enable subsets of cancer cells to survive therapy. In addition to local recurrence, these cells escape a primary tumor and migrate through the stroma to access the circulation and metastasize to different organs, leading to an incurable disease. As such, therapeutics that block migration and invasion of cancer cells may inhibit or reduce metastasis and significantly improve cancer therapy. This is particularly more important for cancers, such as triple negative breast cancer, that currently lack targeted drugs.

METHODS

We used cell migration, 3D invasion, zebrafish metastasis model, and phosphorylation analysis of 43 protein kinases in nine triple negative breast cancer (TNBC) cell lines to study effects of fisetin and quercetin on inhibition of TNBC cell migration, invasion, and metastasis.

RESULTS

Fisetin and quercetin were highly effective against migration of all nine TNBC cell lines with up to 76 and 74% inhibitory effects, respectively. In addition, treatments significantly reduced 3D invasion of highly motile TNBC cells from spheroids into a collagen matrix and their metastasis in vivo. Fisetin and quercetin commonly targeted different components and substrates of the oncogenic PI3K/AKT pathway and significantly reduced their activities. Additionally, both compounds disrupted activities of several protein kinases in MAPK and STAT pathways. We used molecular inhibitors specific to these signaling proteins to establish the migration-inhibitory role of the two phytochemicals against TNBC cells.

CONCLUSIONS

We established that fisetin and quercetin potently inhibit migration of metastatic TNBC cells by interfering with activities of oncogenic protein kinases in multiple pathways.

Verteporfin-Loaded Polymeric Microparticles for Intratumoral Treatment of Brain Cancer

Glioblastoma (GBMs) is the most common and aggressive type of primary brain tumor in adults with dismal prognosis despite radical surgical resection coupled with chemo- and radiotherapy. Recent studies have proposed the use of small-molecule inhibitors, including verteporfin (VP), to target oncogenic networks in cancers. Here we report efficient encapsulation of water-insoluble VP in poly(lactic- co-glycolic acid) microparticles (PLGA MP) of ∼1.5 μm in diameter that allows tunable, sustained release. Treatment with naked VP and released VP from PLGA MP decreased cell viability of patient-derived primary GBM cells in vitro by ∼70%. Moreover, naked VP treatment significantly increased radiosensitivity of GBM cells, thereby enhancing overall tumor cell killing ability by nearly 85%. Our in vivo study demonstrated that two intratumoral administrations of sustained slow-releasing VP-loaded PLGA MPs separated by two weeks significantly attenuated tumor growth by ∼67% in tumor volume in a subcutaneous patient-derived GBM xenograft model over 26 d. Additionally, our in vitro data indicate broader utility of VP for treatment for other solid cancers, including chordoma, malignant meningioma, and various noncentral nervous system-derived carcinomas. Collectively, our work suggests that the use of VP-loaded PLGA MP may be an effective local therapeutic strategy for a variety of solid cancers, including unresectable and orphan tumors, which may decrease tumor burden and ultimately improve patient prognosis.

miR-195 inhibits esophageal cancer cell proliferation and promotes apoptosis by downregulating YAP1

OBJECTIVE

Yes-associated protein 1 (YAP1) regulates a variety of genes related to cell proliferation, cycle and apoptosis, and plays a role in the pathogenesis of esophageal cancer. It was found that the expression of miR-195 was significantly decreased in esophageal cancer tissues, suggesting its anti-cancer effect. Bioinformatics analysis revealed the targeted relationship between miR-195 and the 3'-UTR of YAP1. This study investigated the role of miR-195 in regulating YAP1 expression and affecting proliferation and apoptosis of esophageal cancer cells.

METHODS

The tumor tissue and the adjacent tissue of patients with esophageal cancer were collected to detect the expressions of miR-195 and YAP1. Dual luciferase reporter gene assay was adopted to validate the targeted regulation between miR-195 and YAP1. Esophageal cancer EC9706 cells and normal esophageal epithelial HEEC cells were cultured in vitro to measure the expression of miR-195 and YAP1. EC9706 cells were divided into miR-NC group and miR-195 mimic group followed by analysis of cell apoptosis by flow cytometry and cell proliferation by EdU staining.

RESULTS

Compared with adjacent tissues, miR-195 was significantly decreased, while YAP1 mRNA and protein were significantly upregulated in esophageal cancer tissues. Dual luciferase reporter gene assay confirmed that there was a targeted relationship between miR-195 and YAP1. Compared with HEEC cells, miR-195 expression was declined, whereas YAP1 was elevated in EC9706 cells. Transfection of miR-195 mimic significantly downregulated YAP1 expression, resulting in increased apoptosis and decreased proliferation of EC9706 cells.

CONCLUSION

Decreased expression of miR-195 plays a regulatory role in increasing YAP1 expression and promoting the pathogenesis of esophageal cancer. Elevation of miR-195 inhibites the expression of YAP1, restrains cell proliferation, and promotes cell apoptosis.

Aberrant Promoter Methylation of YAP Gene and its Subsequent Downregulation in Indian Breast Cancer Patients

BACKGROUND

YAP, a potent oncogene and major downstream effector of the mammalian Hippo tumor suppressor pathway can act as either oncogene or tumor suppressor gene based on the type of tissue involved. Despite various studies, the role and mechanism through which YAP mediates its tumor suppressor or oncogenic effects are not yet fully understood. Therefore in the present study we aimed to investigate YAP at DNA, mRNA and protein level and also attempted to correlate our molecular findings with various clinicopathological variables of the patients.

METHODS

The study comprised of a total 137 genetically unrelated women with sporadic breast cancer cases and normal adjacent tissues not infiltrated with tumor. Mutation of YAP gene was analyzed by automated DNA sequencing. YAP promoter methylation was studied using MS-PCR. Expression at mRNA and protein level was studied using qPCR and IHC respectively.

RESULTS

In our study YAP mRNA expression was found to be 8.65 ± 6.17 fold downregulated in 67.15% cases. The expression of YAP when analyzed at the protein level by IHC was found to be absent in 78.83% cases. Results from MS-PCR analysis showed that YAP promoter methylation plays an important role in declining the expression of YAP protein. The absence of YAP protein coincided with 86.60% methylated cases thereby showing a very strong correlation (p = 0.001). We also investigated YAP mutation at the major check point sites in the Hippo pathway and observed no mutation. A significant association was observed on correlating mRNA expression with clinical stages (p = 0.038) and protein expression with ER status (p = 0.018) among Indian breast cancer patients.

CONCLUSION

The expression of YAP was found to be downregulated in response to aberrant promoter methylation. The downregulation of YAP are consistent with previous studies suggesting it to have a tumor suppressive role in breast cancer. We did not observe any mutation at the major check point sites in the Hippo pathway.

Personalizing Breast Cancer Irradiation Using Biology: From Bench to the Accelerator

While adjuvant treatments of early breast cancers (BCs) had significantly improved patients’ overall survival, some of them will still develop locoregional relapses and/or severe late radio-induced toxicities. Here, we propose to review how to personalize locoregional treatment by identifying patients at high and low risk of locoregional relapse, patients at risk of late radio-induced side effects. We will, therefore, discuss how to enhance BC radiosensitivity. Finally, we will address how personalized radiotherapy could be implemented in prospective clinical trials.