An Apoptosis Methylation Prognostic Signature for Early Lung Cancer in the IFCT-0002 Trial

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

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

Mutations in tumor suppressor genes Vhl and Rassf1a cause DNA damage, chromosomal instability and induce gene expression changes characteristic of clear cell renal cell carcinoma

RASSF1A is frequently biallelically inactivated in clear cell renal cell carcinoma (ccRCC) due to loss of chromosome 3p and promoter hypermethylation. Here we investigated the cellular and molecular consequences of single and combined deletion of the Rassf1a and Vhl tumor suppressor genes to model the common ccRCC genotype of combined loss of function of RASSF1A and VHL. In mouse embryonic fibroblasts and in primary kidney epithelial cells, double deletion of Rassf1a and Vhl caused chromosomal segregation defects and increased formation of micronuclei, demonstrating that pVHL and RASSF1A function to maintain genomic integrity. Combined Rassf1a and Vhl deletion in kidney epithelial cells in vivo increased proliferation and caused mild tubular disorganization, but did not lead to the development of kidney tumors. Single cell RNA-sequencing unexpectedly revealed that Rassf1a or Vhl deletion both induce the expression of an overlapping set of genes in a sub-population of proximal tubule cells. Many of these genes are also upregulated in the Vhl/Trp53/Rb1 deficient mouse model of ccRCC. In other subsets of proximal tubule cells, combined Vhl/Rassf1a deletion induced the expression of additional genes that were not upregulated in each of the single knockouts. The expression of the human homologues of Rassf1a-regulated genes correlate negatively with RASSF1 expression levels in human ccRCC. Our results suggest that the loss of RASSF1A function establishes a ccRCC-characteristic gene expression pattern.

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.

Hypoxia-induced activation of NDR2 underlies brain metastases from Non-Small Cell Lung Cancer

The molecular mechanisms induced by hypoxia are misunderstood in non-small cell lung cancer (NSCLC), and above all the hypoxia and RASSF1A/Hippo signaling relationship. We confirmed that human NSCLC (n = 45) as their brain metastases (BM) counterpart are hypoxic since positive with CAIX-antibody (target gene of Hypoxia-inducible factor (HIF)). A severe and prolonged hypoxia (0.2% O2, 48 h) activated YAP (but not TAZ) in Human Bronchial Epithelial Cells (HBEC) lines by downregulating RASSF1A/kinases Hippo (except for NDR2) regardless their promoter methylation status. Subsequently, the NDR2-overactived HBEC cells exacerbated a HIF-1A, YAP and C-Jun-dependent-amoeboid migration, and mainly, support BM formation. Indeed, NDR2 is more expressed in human tumor of metastatic NSCLC than in human localized NSCLC while NDR2 silencing in HBEC lines (by shRNA) prevented the xenograft formation and growth in a lung cancer-derived BM model in mice. Collectively, our results indicated that NDR2 kinase is over-active in NSCLC by hypoxia and supports BM formation. NDR2 expression is thus a useful biomarker to predict the metastases risk in patients with NSCLC, easily measurable routinely by immunohistochemistry on tumor specimens.

Prognostic Factors and Markers in Non-Small Cell Lung Cancer: Recent Progress and Future Challenges

Lung cancer is a highly aggressive neoplasm and, despite the development of recent therapies, tumor progression and recurrence following the initial response remains unsolved. Several questions remain unanswered about non-small cell lung cancer (NSCLC): (1) Which patients will actually benefit from therapy? (2) What are the predictive factors of response to MAbs and TKIs? (3) What are the best combination strategies with conventional treatments or new antineoplastic drugs? To answer these questions, an integrative literature review was carried out, searching articles in PUBMED, NCBI-PMC, Google Academic, and others. Here, we will examine the molecular genetics of lung cancer, emphasizing NSCLC, and delineate the primary categories of inhibitors based on their molecular targets, alongside the main treatment alternatives depending on the type of acquired resistance. We highlighted new therapies based on epigenetic information and a single-cell approach as a potential source of new biomarkers. The current and future of NSCLC management hinges upon genotyping correct prognostic markers, as well as on the evolution of precision medicine, which guarantees a tailored drug combination with precise targeting.

Is Autophagy Always a Barrier to Cisplatin Therapy?

Cisplatin has long been a first-line chemotherapeutic agent in the treatment of cancer, largely for solid tumors. During the course of the past two decades, autophagy has been identified in response to cancer treatments and almost uniformly detected in studies involving cisplatin. There has been increasing recognition of autophagy as a critical factor affecting tumor cell death and tumor chemoresistance. In this review and commentary, we introduce four mechanisms of resistance to cisplatin followed by a discussion of the factors that affect the role of autophagy in cisplatin-sensitive and resistant cells and explore the two-sided outcomes that occur when autophagy inhibitors are combined with cisplatin. Our goal is to analyze the potential for the combinatorial use of cisplatin and autophagy inhibitors in the clinic.

Gene-Specific DNA Methylation Profiles in Pediatric Medulloblastomas

INTRODUCTION

Medulloblastoma is the most common pediatric central nervous tumor of high malignancy that has been classified into both histological subtypes and molecular subgroups by the 2016 World Health Organization classification. However, there is a still need to understand the genomic characteristics and predict the clinical course. The aim of the study is to investigate the significance of the methylation profiles in molecular subclassification and precision medicine of the disease.

METHODS

The study enrolled 47 pediatric medulloblastoma patients. DNA methylation levels of KLF4, SPINT2, RASSF1A, EZH2, ZIC2, and PTCH1 genes were analyzed using methylation-specific pyrosequencing. The significance of the statistical relationship between methylation profiles and clinicopathological parameters including molecular subgroups and histological subtypes, the status of metastasis, and event-free survival were analyzed.

RESULTS

DNA methylation analysis demonstrated that KLF4, PTCH1, and ZIC2 hypermethylation were associated with the SHH-activated subgroup, whereas both SPINT2 and RASSF1A hypermethylation were associated with metastatic disease. EZH2 gene was not methylated in any of the samples.

CONCLUSION

We think that customized DNA methylation profiling may be a useful tool in the molecular subclassification of pediatric medulloblastoma and a potential technical approach in precision medicine.

DNA Methylation in Lung Cancer: Mechanisms and Associations with Histological Subtypes, Molecular Alterations, and Major Epidemiological Factors

Lung cancer is the major leading cause of cancer-related mortality worldwide. Multiple epigenetic factors-in particular, DNA methylation-have been associated with the development of lung cancer. In this review, we summarize the current knowledge on DNA methylation alterations in lung tumorigenesis, as well as their associations with different histological subtypes, common cancer driver gene mutations (e.g., KRAS, EGFR, and TP53), and major epidemiological risk factors (e.g., sex, smoking status, race/ethnicity). Understanding the mechanisms of DNA methylation regulation and their associations with various risk factors can provide further insights into carcinogenesis, and create future avenues for prevention and personalized treatments. In addition, we also highlight outstanding questions regarding DNA methylation in lung cancer to be elucidated in future studies.

Predictive value of unmethylated RASSF1A on disease progression in non-small cell lung cancer patients receiving pemetrexed-based chemotherapy

BACKGROUND AND OBJECTIVE

Chemotherapy remains the basis of the treatment of lung cancer, and screening biomarkers with predictive value for chemotherapy is of great interest. The present study focused on status of genes methylation in NSCLC patients receiving pemetrexed- or gemcitabine-based chemotherapy.

PATIENTS AND METHODS

Promoter methylation of Ras association domain family (RASSF1A) and short stature homeobox 2 (SHOX2) was examined in bronchoalveolar lavage (BAL) from 117 NSCLC patients treated with chemotherapy. Multivariate analysis was used to identify the predictive value of gene methylation. Progression-free survival (PFS) rather than overall survival (OS) was used as the clinical outcome to minimize the impact of chemotherapy on gene methylation.

RESULTS

The methylation of RASSF1A and SHOX2 was significantly associated with shorter PFS (RASSF1A: HR = 2.355, 95% CI: 1.533-3.617, P< 0.0001; SHOX2: HR = 2.123, 95% CI: 1.392-3.236, P= 0.0004). After adjusting for confounding factors, RASSF1A methylation was still a predictive factor for PFS (HR = 1.765, 95% CI: 1.064-2.928, P= 0.0278). In the pemetrexed group, unmethylated RASSF1A could be used to predict longer PFS (P= 0.0001), and no predictive value was found in the gemcitabine group.

CONCLUSION

Unmethylated RASSF1A is a favorable prognostic indicator for patients receiving pemetrexed doublets. Because of the promoting effect of most chemotherapeutic drugs on gene methylation, unmethylated RASSF1A is not suitable as a predictor for gemcitabine doublets.

Identification of prognostic signature of non-small cell lung cancer based on TCGA methylation data

Non–small lung cancer (NSCLC) is a common malignant disease with very poor outcome. Accurate prediction of prognosis can better guide patient risk stratification and treatment decision making, and could optimize the outcome. Utilizing clinical and methylation/expression data in The Cancer Genome Atlas (TCGA), we conducted comprehensive evaluation of early-stage NSCLC to identify a methylation signature for survival prediction. 349 qualified cases of NSCLC with curative surgery were included and further grouped into the training and validation cohorts. We identified 4000 methylation loci with prognostic influence on univariate and multivariate regression analysis in the training cohort. KEGG pathway analysis was conducted to identify the key pathway. Hierarchical clustering and WGCNA co-expression analysis was performed to classify the sample phenotype and molecular subtypes. Hub 5′-C-phosphate-G-3′ (CpG) loci were identified by network analysis and then further applied for the construction of the prognostic signature. The predictive power of the prognostic model was further validated in the validation cohort. Based on clustering analysis, we identified 6 clinical molecular subtypes, which were associated with different clinical characteristics and overall survival; clusters 4 and 6 demonstrated the best and worst outcomes. We identified 17 hub CpG loci, and their weighted combination was used for the establishment of a prognostic model (RiskScore). The RiskScore significantly correlated with post-surgical outcome; patients with a higher RiskScore have worse overall survival in both the training and validation cohorts (P < 0.01). We developed a novel methylation signature that can reliably predict prognosis for patients with NSCLC.

RASSF1A: A promising target for the diagnosis and treatment of cancer

The Ras association domain family 1 isoform A (RASSF1A), a tumor suppressor, regulates several tumor-related signaling pathways and interferes with diverse cellular processes. RASSF1A is frequently demonstrated to be inactivated by hypermethylation in numerous types of solid cancers. It is also associated with lymph node metastasis, vascular invasion, and chemo-resistance. Therefore, reactivation of RASSF1A may be a viable strategy to block tumor progress and reverse drug resistance. In this review, we have summarized the clinical value of RASSF1A for screening, staging, and therapeutic management of human malignancies. We also highlighted the potential mechanism of RASSF1A in chemo-resistance, which may help identify novel drugs in the future.

RASSF1A, puppeteer of cellular homeostasis, fights tumorigenesis, and metastasis-an updated review

The Ras association domain family protein1 isoform A (RASSF1A) is a well-known tumor-suppressor protein frequently inactivated in various human cancers. Consistent with its function as a molecular scaffold protein, referred to in many studies, RASSF1A prevents initiation of tumorigenesis, growth, and dissemination through different biological functions, including cell cycle arrest, migration/metastasis inhibition, microtubular stabilization, and apoptosis promotion. As a regulator of key cancer pathways, namely Ras/Rho GTPases and Hippo signaling without ignoring strong interaction with microtubules, RASSF1A is indeed one of the guardians of cell homeostasis. To date, as we approach the two decade anniversary of RASSF1A's discovery, this review will summarize our current knowledge on the RASSF1A key interactions as a tumor suppressor and discuss their impact on cell fate during carcinogenesis. This could facilitate a deeper understanding of tumor development and provide us with new strategies in cancer treatment by targeting the RASSF1A pathway.

Role of the YAP-1 Transcriptional Target cIAP2 in the Differential Susceptibility to Chemotherapy of Non-Small-Cell Lung Cancer (NSCLC) Patients with Tumor RASSF1A Gene Methylation from the Phase 3 IFCT-0002 Trial

RASSF1 gene methylation predicts longer disease-free survival (DFS) and overall survival (OS) in patients with early-stage non-small-cell lung cancer treated using paclitaxel-based neo-adjuvant chemotherapy compared to patients receiving a gemcitabine-based regimen, according to the randomized Phase 3 IFCT (Intergroupe Francophone de Cancérologie Thoracique)-0002 trial. To better understand these results, this study used four human bronchial epithelial cell (HBEC) models (HBEC-3, HBEC-3-RasV12, A549, and H1299) and modulated the expression of RASSF1A or YAP-1. Wound-healing, invasion, proliferation and apoptosis assays were then carried out and the expression of YAP-1 transcriptional targets was quantified using a quantitative polymerase chain reaction. This study reports herein that gemcitabine synergizes with RASSF1A, silencing to increase the IAP-2 expression, which in turn not only interferes with cell proliferation but also promotes cell migration. This contributes to the aggressive behavior of RASSF1A-depleted cells, as confirmed by a combined knockdown of IAP-2 and RASSF1A. Conversely, paclitaxel does not increase the IAP-2 expression but limits the invasiveness of RASSF1A-depleted cells, presumably by rescuing microtubule stabilization. Overall, these data provide a functional insight that supports the prognostic value of RASSF1 gene methylation on survival of early-stage lung cancer patients receiving perioperative paclitaxel-based treatment compared to gemcitabine-based treatment, identifying IAP-2 as a novel biomarker indicative of YAP-1-mediated modulation of chemo-sensitivity in lung cancer.

Promoter Hypermethylation of Genes Encoding for RASSF/Hippo Pathway Members Reveals Specific Alteration Pattern in Diffuse Gliomas

Ras association domain family (RASSF)/Hippo pathway alterations are poorly characterized in diffuse gliomas. We assayed promoter methylation of LATS1/2, MST1(STK4)/MST2(STK3), RASSF1, RASSF2, Nore1A/RASSF5, RASSF6, and RASSF10 genes in 133 diffuse gliomas. The RASSF/Hippo pathway was highly silenced in gliomas, particularly RASSF1A (79.4%) and LATS2 (35.9%). The most frequent combination of promoter hypermethylation of one RASSF gene and one Hippo pathway member's gene was RASSF1/LATS2-coupled hypermethylation [n = 44 (33.08%)]. Hypermethylated profiles were related to IDH mutation, yet not randomly in IDH-mutated gliomas, because LATS2 promoter hypermethylation was more frequent in oligodendroglioma than in astrocytoma. RASSF1 and LATS2 promoter hypermethylation predicted a longer overall survival (OS). Considering hypermethylation of these two promoters, Cox proportional hazard regression analysis categorized the patients into three prognostic groups: i) high risk of death (n = 24; both RASSF1 and LATS2 unmethylated promoters; median OS, 13 months); ii) intermediate risk of death (n = 65; RASSF1 or LATS2 hypermethylated promoter; median OS, 50.5 months; HR = 3.3; 95% CI, 1.6-6.4; P = 0.001); and iii) low risk of death (n = 44; both RASSF1 and LATS2 hypermethylated promoters; median OS, 119 months; HR = 75.1; 95% CI, 3.3-15.1; P = 0.001). We have thus highlighted a simple two-gene (RASSF1/LATS2) methylation signature as a tool to stratify different prognostic groups of patients with diffuse glioma, adding further prognostic information within the IDH-mutated group.

NDR2 kinase contributes to cell invasion and cytokinesis defects induced by the inactivation of RASSF1A tumor-suppressor gene in lung cancer cells

Background

RASSF1A, a tumor suppressor gene, is frequently inactivated in lung cancer leading to a YAP-dependent epithelial-mesenchymal transition (EMT). Such effects are partly due to the inactivation of the anti-migratory RhoB GTPase via the inhibitory phosphorylation of GEF-H1, the GDP/GTP exchange factor for RhoB. However, the kinase responsible for RhoB/GEF-H1 inactivation in RASSF1A-depleted cells remained unknown.

Methods

NDR1/2 inactivation by siRNA or shRNA effects on epithelial-mesenchymal transition, invasion, xenograft formation and growth in SCID−/− Beige mice, apoptosis, proliferation, cytokinesis, YAP/TAZ activation were investigated upon RASSF1A loss in human bronchial epithelial cells (HBEC).

Results

We demonstrate here that depletion of the YAP-kinases NDR1/2 reverts migration and metastatic properties upon RASSF1A loss in HBEC. We show that NDR2 interacts directly with GEF-H1 (which contains the NDR phosphorylation consensus motif HXRXXS/T), leading to GEF-H1 phosphorylation. We further report that the RASSF1A/NDR2/GEF-H1/RhoB/YAP axis is involved in proper cytokinesis in human bronchial cells, since chromosome proper segregation are NDR-dependent upon RASSF1A or GEF-H1 loss in HBEC.

Conclusion

To summarize, our data support a model in which, upon RASSF1A silencing, NDR2 gets activated, phosphorylates and inactivates GEF-H1, leading to RhoB inactivation. This cascade induced by RASSF1A loss in bronchial cells is responsible for metastasis properties, YAP activation and cytokinesis defects.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1145-8) contains supplementary material, which is available to authorized users.

Prognostic value of RASSF1A methylation status in non-small cell lung cancer (NSCLC) patients: A meta-analysis of prospective studies

Objective: Ras association domain family 1 A (RASSF1A) has been regarded as a biomarker predicting the prognosis of non-small cell lung cancer (NSCLC), but previous findings are inconsistent. This meta-analysis of prospective studies aimed to assess the value of RASSF1A methylation in predicting the prognosis of NSCLC patients. Methods: Studies were searched in PubMed and Web of Science. The estimates of the effects and the corresponding 95% confidence intervals (95% CIs) were used for the analyses. The overall effects of RASSF1A methylation on overall survival (OS) were estimated, after which subgroup analysis based on regions was conducted. Sensitivity analyses were conducted to restrict the studies with certain features. Results: A total of 16 studies with 2210 participants were included in this meta-analysis. The overall analysis result indicated that RASSF1A methylation had no statistically significant effects on OS of NSCLC patients (HR = 1.28; 95% CI 0.86-1.70), which were confirmed by the subgroup analysis. However, the sensitivity analysis indicated that RASSF1A methylation from lung cancer tissues was significantly associated with lower OS (HR = 1.24; 95% CI 1.04-1.45). Conclusion: RASSF1A methylation in lung cancer tissue can serve as a prognostic factor of NSCLC. More studies are needed to uncover the underlying mechanisms.

MST1/Hippo promoter gene methylation predicts poor survival in patients with malignant pleural mesothelioma in the IFCT-GFPC-0701 MAPS Phase 3 trial

BACKGROUND

The Mesothelioma Avastin Cisplatin Pemetrexed Study (MAPS/NCT00651456) phase 3 trial demonstrated the superiority of bevacizumab plus pemetrexed-cisplatin triplet over chemotherapy alone in 448 malignant pleural mesothelioma (MPM) patients. Here, we evaluated the prognostic role of Hippo pathway gene promoter methylation.

METHODS

Promoter methylations were assayed using methylation-specific polymerase chain reaction in samples from 223 MAPS patients, evaluating their prognostic value for overall survival (OS) and disease-free survival in univariate and multivariate analyses. MST1 inactivation effects on invasion, soft agar growth, apoptosis, proliferation, and YAP/TAZ activation were investigated in human mesothelial cell lines.

RESULTS

STK4 (MST1) gene promoter methylation was detected in 19/223 patients tested (8.5%), predicting poorer OS in univariate and multivariate analyses (adjusted HR: 1.78, 95% CI (1.09-2.93), p = 0.022). Internal validation by bootstrap resampling supported this prognostic impact. MST1 inactivation reduced cellular basal apoptotic activity while increasing proliferation, invasion, and soft agar or in suspension growth, resulting in nuclear YAP accumulation, yet TAZ cytoplasmic retention in mesothelial cell lines. YAP silencing decreased invasion of MST1-depleted mesothelial cell lines.

CONCLUSIONS

MST1/hippo kinase expression loss is predictive of poor prognosis in MPM patients, leading to nuclear YAP accumulation and electing YAP as a putative target for therapeutic intervention in human MPM.

A role for RASSF1A in tunneling nanotube formation between cells through GEFH1/Rab11 pathway control

BACKGROUND

By allowing intercellular communication between cells, tunneling nanotubes (TNTs) could play critical role in cancer progression. If TNT formation is known to require cytoskeleton remodeling, key mechanism controlling their formation remains poorly understood.

METHODS

The cells of human bronchial (HBEC-3, A549) or mesothelial (H2452, H28) lines are transfected with different siRNAs (inactive, anti-RASSF1A, anti-GEFH1 and / or anti-Rab11). At 48 h post-transfection, i) the number and length of the nanotubes per cell are quantified, ii) the organelles, previously labeled with specific tracers, exchanged via these structures are monitored in real time between cells cultured in 2D or 3D and in normoxia, hypoxia or in serum deprivation condition.

RESULTS

We report that RASSF1A, a key-regulator of cytoskeleton encoded by a tumor-suppressor gene on 3p chromosome, is involved in TNTs formation in bronchial and pleural cells since controlling proper activity of RhoB guanine nucleotide exchange factor, GEF-H1. Indeed, the GEF-H1 inactivation induced by RASSF1A silencing, leads to Rab11 accumulation and subsequent exosome releasing, which in turn contribute to TNTs formation. Finally, we provide evidence involving TNT formation in bronchial carcinogenesis, by reporting that hypoxia or nutriment privation, two almost universal conditions in human cancers, fail to prevent TNTs induced by the oncogenic RASSF1A loss of expression.

CONCLUSIONS

This finding suggests for the first time that loss of RASSF1A expression could be a potential biomarker for TNTs formation, such TNTs facilitating intercellular communication favoring multistep progression of bronchial epithelial cells toward overt malignancy.

Epigenetic predictive biomarkers for response or outcome to platinum-based chemotherapy in non-small cell lung cancer, current state-of-art

Platinum-based chemotherapy is commonly used to treat non-small cell lung cancer (NSCLC). However, its efficacy is limited and no molecular biomarkers that predict response are available. In this review, we summarize current knowledge concerning potential epigenetic predictive markers for platinum-based chemotherapy response in NSCLC. A systematic search of PubMed and ClinicalTrials.gov using keywords "non-small cell lung cancer" combined with "chemotherapy predictive biomarkers", "chemotherapy epigenetics biomarkers", "chemotherapy microRNA biomarkers", "chemotherapy DNA methylation" and "chemotherapy miRNA biomarkers" revealed 1740 articles from PubMed and 36 clinical trials. Finally, 22 papers and no trials fulfilled the review criteria. Among miRNA, combination of miR-1290, miR-196b and miR-135a in tumor tissue, and miR-21, miR-25, miR27b, and miR-326 in plasma were predictive for response to platinum-based chemotherapy in advanced NSCLC. RASSF1A methylation measured in tumor or blood was predictive for response to neoadjuvant chemotherapy. These biomarkers remain experimental and none have been tested in a prospective trial.

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

Lung cancer is the leading cause of cancer death in the world and there is no current treatment able to efficiently treat the disease as the tumor is often diagnosed at an advanced stage. Moreover, cancer cells are often resistant or acquire resistance to the treatment. Further knowledge of the mechanisms driving lung tumorigenesis, aggressiveness, metastasization, and resistance to treatments could provide new tools for detecting the disease at an earlier stage and for a better response to therapy. In this scenario, Yes Associated Protein (YAP) and Trascriptional Coactivator with PDZ-binding motif (TAZ), the final effectors of the Hippo signaling transduction pathway, are emerging as promising therapeutic targets. Here, we will discuss the most recent advances made in YAP and TAZ biology in lung cancer and, more importantly, on the newly discovered mechanisms of YAP and TAZ inhibition in lung cancer as well as their clinical implications.

EGFL7 and RASSF1 promoter hypermethylation in epithelial ovarian cancer

DNA methylation is one of the epigenetic mechanisms associated with gene expression and plays a key role as in activation and deactivation of oncogenes and tumor suppressor genes, respectively. This study employed DNA methylation array to identify methylated genes which are highly correlated with various phenotypes of epithelial ovarian cancer (EOC) in Thai patients and to quantify promoter CpG-island methylation of candidate genes. Tissues from patients with serous and non-serous EOC showed significantly higher promoter methylation of EGFL7 and RASSF1 compared to benign cases. These results indicate the potential of investigating promoter CpG-island methylation of cancer-associated genes as biomarkers of disease progression and even possibly of early detection.

MSH2/BRCA1 expression as a DNA-repair signature predicting survival in early-stage lung cancer patients from the IFCT-0002 Phase 3 Trial

Introduction

DNA repair is a double-edged sword in lung carcinogenesis. When defective, it promotes genetic instability and accumulated genetic alterations. Conversely these defects could sensitize cancer cells to therapeutic agents inducing DNA breaks.

Methods

We used immunohistochemistry (IHC) to assess MSH2, XRCC5, and BRCA1 expression in 443 post-chemotherapy specimens from patients randomized in a Phase 3 trial, comparing two neoadjuvant regimens in 528 Stage I-II non-small cell lung cancer (NSCLC) patients (IFCT-0002). O6MGMT promoter gene methylation was analyzed in a subset of 208 patients of the same trial with available snap-frozen specimens.

Results

Median follow-up was from 90 months onwards. Only high BRCA1 (n = 221, hazard ratio [HR] = 1.58, 95% confidence interval [CI] [1.07-2.34], p = 0.02) and low MSH2 expression (n = 356, HR = 1.52, 95% CI [1.11-2.08], p = 0.008) significantly predicted better overall survival (OS) in univariate and multivariate analysis. A bootstrap re-sampling strategy distinguished three patient groups at high (n = 55, low BRCA1 and high MSH2, median OS >96 months, HR = 2.5, 95% CI [1.45-4.33], p = 0.001), intermediate (n = 82, median OS = 73.4 p = 0.0596), and low (high BRCA1 and low MSH2, n = 67, median OS = ND, HR = 0.51, 95% CI [0.31-0.83], p = 0.006) risk of death.

Interpretation

DNA repair protein expression assessment identified three different groups of risk of death in early-stage lung cancer patients, according to their tumor MSH2 and BRCA1 expression levels. These results deserve prospective evaluation of MSH2/BRCA1 theranostic value in lung cancer patients treated with combinations of DNA-damaging chemotherapy and drugs targeting DNA repair, such as Poly(ADP-ribose) polymerase (PARP) inhibitors.

[Current knowledge on perioperative treatments of non-small cell lung carcinomas]

Surgery is still the main treatment in early-stage of non-small cell lung cancer with 5-year survival of stage IA patients exceeding 80%, but 5-year survival of stage II patients rapidly decreasing with tumor size, N status, and visceral pleura invasion. The major metastatic risk in such patients has supported clinical research assessing systemic or loco-regional perioperative treatments. Modern phase 3 trials clearly validated adjuvant or neo-adjuvant platinum-based chemotherapy in resected stage I-III patients as a standard treatment of which value has been reassessed several independent meta-analyses, showing a 5% benefit in 5y-survival, and a decrease of the relative risk for death around from 12 to 25%. Conversely perioperative treatments were not validated for stage IA and IB patients. In more advanced stage patients, neo-adjuvant radio-chemotherapy has not been validated either. Adjuvant radiotherapy for N2 patients is currently tested in the large international phase 3 trial Lung-ART/IFCT-0503. The development of video-assisted thoracic surgery (VATS) has helped adjuvant chemotherapies for elderly patients. Perioperative targeted treatments in NSCLC with EGFR or ALK molecular alterations is currently assessed in the U.S. ALCHEMIST prospective trial. Finally, the role of immune check-points inhibitors is currently evaluated in a large international phase 3 trial testing adjuvant anti-PD-L1 monoclonal antibody, the BR31/IFCT-1401 trial, while a proof-of principle neo-adjuvant trial IONESCO/IFCT-1601, has just begun by the end of the 2016 year, with survival results of both trials expected in 5 to 7 years.

RHOB expression controls the activity of serine/threonine protein phosphatase PP2A to modulate mesenchymal phenotype and invasion in non-small cell lung cancers

Metastatic dissemination is the cause of death in the vast majority of cancers, including lung cancers. In order to metastasize, tumor cells must undergo a well-known series of changes, however the molecular details of how they manage to overcome the barriers at each stage remain incomplete. One critical step is acquiring the ability to migrate through the extracellular matrix. Loss of expression of the RAS-related small GTPase RHOB is a common feature of lung cancer progression, and we recently reported that this induces an epithelial-to-mesenchymal transition (EMT) that is dependent on SLUG overexpression and E-Cadherin inhibition and is characterized by 3-dimensional cell shape reorganization and the increased invasiveness of bronchial cells. RHOB loss was found to induce AKT1 activation, which in turn activates RAC1 through its GEF TRIO. Further investigation of this pathway revealed that RHOB interacts with and positively regulates PP2A, one of the major cellular serine-threonine phosphatases, by recruiting its regulatory subunit B55. Here we discuss the role of this newly discovered RHOB/PP2A/AKT1/RAC1 pathway in relation to mesenchymal migration and invasion in lung cancer.

Caspase-related apoptosis genes in gliomas by RNA-seq and bioinformatics analysis

Gliomas are the most common malignant tumors of the brain. The aim of this study is to identify caspase-dependent apoptotic genes and uncover their potential regulatory mechanism in glioma progression. Human glioma cell line U251 was used. Three experiment groups were set as control group, H₂O₂ group (treated with H₂O₂) and caspase inhibitor group (treated with caspase inhibitor). For samples in each group, RNA-sequencing was performed on Illumina platform and differentially expressed genes (DEGs) between any two of the three groups were selected using NOISeq package. By overlapping analysis, the caspase inhibitor-related DEGs were further screened out, followed by enrichment analyses. Drugs associating with these genes were selected by WebGestalt. Protein-protein interaction (PPI) network analysis was conducted based on SRINIG database. A set of 105 caspase inhibitor-related DEGs were identified, which were significantly enriched in cellular components related functions (for example, TUBB2A, RPSA and RPL5); and metabolism related pathways (for example, PSMC3, KHSRP, RPL5 and RPSA). In addition, KHSRP and TUBB2A were significantly associated with several drugs such as cefotaxime, cefacetrile and netilmicin. Besides, PSMC3 and RPL5 were identified as crucial nodes in the PPI network. Several crucial genes in gliomas cells such as TUBB2A, RPSA, RPL5, PSMC3 and KHSRP were identified, which might play significant roles in apoptosis in a caspase-dependent manner. These genes might also involve in the regulation of metabolism related functions and pathways. KHSRP and TUBB2A might be novel targets of three drugs, cefotaxime, cefacetrile and netilmicin.

RASSF1A Suppresses the Invasion and Metastatic Potential of Human Non-Small Cell Lung Cancer Cells by Inhibiting YAP Activation through the GEF-H1/RhoB Pathway

Inactivation of the tumor suppressor gene RASSF1A by promoter hypermethylation represents a key event underlying the initiation and progression of lung cancer. RASSF1A inactivation is also associated with poor prognosis and may promote metastatic spread. In this study, we investigated how RASSF1A inactivation conferred invasive phenotypes to human bronchial cells. RNAi-mediated silencing of RASSF1A induced epithelial-to-mesenchymal transition (EMT), fomenting a motile and invasive cellular phenotype in vitro and increased metastatic prowess in vivo. Mechanistic investigations revealed that RASSF1A blocked tumor growth by stimulating cofilin/PP2A-mediated dephosphorylation of the guanine nucleotide exchange factor GEF-H1, thereby stimulating its ability to activate the antimetastatic small GTPase RhoB. Furthermore, RASSF1A reduced nuclear accumulation of the Hippo pathway transcriptional cofactor Yes-associated protein (YAP), which was reinforced by RhoB activation. Collectively, our results indicated that RASSF1 acts to restrict EMT and invasion by indirectly controlling YAP nuclear shuttling and activation through a RhoB-regulated cytoskeletal remodeling process, with potential implications to delay the progression of RASSF1-hypermethylated lung tumors.

Clinical utility of RASSF1A methylation in human malignancies

The high frequency of RASSF1A methylation has been noted in a vast number of patients in a broad spectrum of malignancies, suggesting that RASSF1A inactivation is associated with cancer pathogenesis. However, whether this recurrent incidence of RASSF1A hypermethylation in human malignancies and its association with more aggressive tumour phenotype is a frequent event across different cancer types has not yet been discussed. In this review, we interrogated existing evidence for association of RASSF1A hypermethylation with clinicopathological characteristics that can indicate more invasive lesions.

Prognostic and predictive biomarkers in early stage non-small cell lung cancer: tumor based approaches including gene signatures

In early stage non-small cell lung cancer (NSCLC) large randomized trials have demonstrated that in patients with radically resected disease adjuvant chemotherapy improves 5-year survival rates. However, a customization of systemic treatment is needed to avoid treatments in patients cured by surgery alone or to justify the use of adjuvant chemotherapy in high risk patients, including those in stage IA. Recently, the possibility of identifying prognostic and predictive factors related to the genetic signatures of the tumor that could affect adjuvant and neo-adjuvant treatment choices for resectable non-small cell lung cancer (NSCLC) has been of interest. This review summarizes the current status and future opportunities for clinical application of genotyping and genomic tests in early NSCLC.

Clinical significance of DAPK promoter hypermethylation in lung cancer: a meta-analysis

Death-associated protein kinase 1 (DAPK) is an important serine/threonine kinase involved in various cellular processes, including apoptosis, autophagy, and inflammation. DAPK expression and activity are deregulated in a variety of diseases including cancer. Methylation of the DAPK gene is common in many types of cancer and can lead to loss of DAPK expression. However, the association between DAPK promoter hypermethylation and the clinicopathological significance of lung cancer remains unclear. In this study, we searched the MEDLINE, PubMed, Web of Science, and Scopus databases, systematically investigated the studies of DAPK promoter hypermethylation in lung cancer and quantified the association between DAPK promoter hypermethylation and its clinicopathological significance by meta-analysis. We observed that the frequency of DAPK methylation was significantly higher in lung cancer than in non-malignant lung tissues (odds ratio 6.02, 95% confidence interval 3.17-11.42, P<0.00001). The pooled results also showed the presence of a prognostic impact of DAPK gene methylation in lung cancer patients (odds ratio 3.63, 95% confidence interval 1.09-12.06, P=0.04). In addition, we summarized these findings and discuss tumor suppressor function, clinicopathological significance, and potential drug targeting of DAPK in lung cancer.

Epigenetic perspectives on cancer chemotherapy response

Epigenetic programs are now widely recognized as being critical to the biological processes of cancer genesis. However, it has not been comprehensively understood how and to what degree they can influence anticancer drugs responses. The development of drugs targeting epigenetic regulation has generated great enthusiasm, with a growing number in clinical development. We highlight here that epigenetic modifications can be involved in the regulation of genes responsible for the absorption, distribution, metabolism and excretion of drugs and for the pathological progression of cancer, thereby affecting anticancer drug responses. The major epigenetic regulatory mechanisms are reviewed, including DNA methylation, miRNA regulation and histone modification, with the aim of promoting rational use of anticancer drugs in the clinic and epigenetic drug development.

RASSF1A promoter hypermethylation is a strong biomarker of poor survival in patients with salivary adenoid cystic carcinoma in a Chinese population

In addition to the clinicopathological parameters, molecular biomarkers are becoming increasingly important in the prognostic evaluation of cancer patients. This study aimed to determine the molecular alterations in the RAS association domain family protein1A gene (RASSF1A) in salivary adenoid cystic carcinoma (ACC) and to evaluate the potential of such alterations as prognostic markers. One hundred and sixty-seven ACC tumor tissues and 50 samples of matched normal salivary gland tissues from the same patients were analyzed for RASSF1A promoter methylation status by bisulfite sequencing PCR (BSP) and/or methylation-specific PCR (MSP). Fifty ACC tumor tissues and matched normal salivary gland tissues were analyzed for loss of heterozygosity (LOH) by examining two microsatellite markers (D3S1478, D3S1621) at 3p21. RASSF1A gene mutations were detected by direct sequencing of all six exons in 50 tumor and normal tissue specimens. Over-all, RASSF1A promoter hypermethylation was detected in 35.3% (59/167) of ACC tissues and was associated with histologically solid tumor pattern (P = 0.002) and advanced TNM stage (P = 0.014). RASSF1A LOH was observed in 18.0% (9/50) of cases, and no somatic mutation of RASSF1A was detected in any cases. RASSF1A promoter methylation was associated with the poor over-all survival (Log-rank test, P <0.001) and disease-free survival (Log-rank test, P <0.001) and identified as an independent predicator of over-all patient survival (P = 0.009) and disease-free survival (P <0.001). It was concluded that RASSF1A methylation is involved in the development, differentiation and progression of ACC and is a strong independent biomarker of poor survival in ACC patients in a Chinese population.

RASSF1A-LATS1 signalling stabilizes replication forks by restricting CDK2-mediated phosphorylation of BRCA2

Genomic instability is a key hallmark of cancer leading to tumour heterogeneity and therapeutic resistance. BRCA2 has a fundamental role in error-free DNA repair but also sustains genome integrity by promoting RAD51 nucleofilament formation at stalled replication forks. CDK2 phosphorylates BRCA2 (pS3291-BRCA2) to limit stabilizing contacts with polymerized RAD51; however, how replication stress modulates CDK2 activity and whether loss of pS3291-BRCA2 regulation results in genomic instability of tumours are not known. Here we demonstrate that the Hippo pathway kinase LATS1 interacts with CDK2 in response to genotoxic stress to constrain pS3291-BRCA2 and support RAD51 nucleofilaments, thereby maintaining genomic fidelity during replication stalling. We also show that LATS1 forms part of an ATR-mediated response to replication stress that requires the tumour suppressor RASSF1A. Importantly, perturbation of the ATR-RASSF1A-LATS1 signalling axis leads to genomic defects associated with loss of BRCA2 function and contributes to genomic instability and 'BRCA-ness' in lung cancers.

Discovery and development of DNA methylation-based biomarkers for lung cancer

Lung cancer remains the primary cause of cancer-related deaths worldwide. Improved tools for early detection and therapeutic stratification would be expected to increase the survival rate for this disease. Alterations in the molecular pathways that drive lung cancer, which include epigenetic modifications, may provide biomarkers to help address this major unmet clinical need. Epigenetic changes, which are defined as heritable changes in gene expression that do not alter the primary DNA sequence, are one of the hallmarks of cancer, and prevalent in all types of cancer. These modifications represent a rich source of biomarkers that have the potential to be implemented in clinical practice. This perspective describes recent advances in the discovery of epigenetic biomarkers in lung cancer, specifically those that result in the methylation of DNA at CpG sites. We discuss one approach for methylation-based biomarker assay development that describes the discovery at a genome-scale level, which addresses some of the practical considerations for design of assays that can be implemented in the clinic. We emphasize that an integrated technological approach will enable the development of clinically useful DNA methylation-based biomarker assays. While this article focuses on current literature and primary research findings in lung cancer, the principles we describe here apply to the discovery and development of epigenetic biomarkers for other types of cancer.

Site-specific methylated reporter constructs for functional analysis of DNA methylation

Methods to experimentally alter and functionally evaluate cytosine methylation in a site-specific manner have proven elusive. We describe a site-specific DNA methylation method, using synthetically methylated primers and high fidelity PCR coupled with ligation of reporter constructs. We applied this method to introduce methylated cytosines into fragments of the respective DAPK and RASSF1A promoters that had been cloned into luciferase reporters. We found that methylation of 3-7 residue CpG clusters that were 5' adjacent to the transcription start site (TSS) of the DAPK gene produced up to a 54% decrease in promoter activity (p<0.01). Similarly, for RASSF1A promoter reporter constructs, the methylation of either of two clusters of four CpGs each, but not an intervening cluster, produced a 63% decrease in promoter activity (p<0.01), suggesting that precise mCpG position is crucial, and factors other than simple proximity to the TSS are at play. Chromatin immunoprecipitation analysis of these reporter constructs demonstrated that transcription factor Oct-1 and Sp1 preferentially bound the unmethylated vs. methylated DAPK or RASSF1A promoter reporter constructs at the functional CpG sites. Histone H1, hnRNP1, and MeCP2 showed preferential binding to methylated sequence at functional sites in these reporter constructs, as well as highly preferential (> 8-80-fold) binding to native methylated vs. unmethylated chromatin. These results suggest that: (1) site-specific, precision DNA methylation of a reporter construct can be used for functional analysis of commonly observed gene promoter methylation patterns; (2) the reporter system contains key elements of the endogenous chromatin machinery.

Molecular biology of lung cancer: Diagnosis and management of lung cancer, 3rd ed: American College of Chest Physicians evidence-based clinical practice guidelines

Based on recent bench and clinical research, the treatment of lung cancer has been refined, with treatments allocated according to histology and specific molecular features. For example, targeting mutations such as epidermal growth factor receptor (EGFR) with tyrosine kinase inhibitors has been particularly successful as a treatment modality, demonstrating response rates in selected patients with adenocarcinoma tumors harboring EGFR mutations that are significantly higher than those for conventional chemotherapy. However, the development of new targeted therapies is, in part, highly dependent on an improved understanding of the molecular underpinnings of tumor initiation and progression, knowledge of the role of molecular aberrations in disease progression, and the development of highly reproducible platforms for high-throughput biomarker discovery and testing. In this article, we review clinically relevant research directed toward understanding the biology of lung cancer. The clinical purposes of this research are (1) to identify susceptibility variants and field molecular alterations that will promote the early detection of tumors and (2) to identify tumor molecular alterations that serve as therapeutic targets, prognostic biomarkers, or predictors of tumor response. We focus on research developments in the understanding of lung cancer somatic DNA mutations, chromosomal aberrations, epigenetics, and the tumor microenvironment, and how they can advance diagnostics and therapeutics.

DNA methylation profiles at precancerous stages associated with recurrence of lung adenocarcinoma

The aim of this study was to clarify the significance of DNA methylation alterations at precancerous stages of lung adenocarcinoma. Using single-CpG resolution Infinium array, genome-wide DNA methylation analysis was performed in 36 samples of normal lung tissue obtained from patients without any primary lung tumor, 145 samples of non-cancerous lung tissue (N) obtained from patients with lung adenocarcinomas, and 145 samples of tumorous tissue (T). Stepwise progression of DNA methylation alterations from normal lung tissue to non-cancerous lung tissue obtained from patients with lung adenocarcinomas, and then tumorous tissue samples, was observed at 3,270 CpG sites, suggesting that non-cancerous lung tissue obtained from patients with lung adenocarcinomas was at precancerous stages with DNA methylation alterations. At CpG sites of 2,083 genes, DNA methylation status in samples of non-cancerous lung tissue obtained from patients with lung adenocarcinomas was significantly correlated with recurrence after establishment of lung adenocarcinomas. Among such recurrence-related genes, 28 genes are normally unmethylated (average β-values based on Infinium assay in normal lung tissue samples was less than 0.2) and their DNA hypermethylation at precancerous stages was strengthened during progression to lung adenocarcinomas (Δβ(T-N)>0.1). Among these 28 genes, we focused on 6 for which implications in transcription regulation, apoptosis or cell adhesion had been reported. DNA hypermethylation of the ADCY5, EVX1, GFRA1, PDE9A, and TBX20 genes resulted in reduced mRNA expression in tumorous tissue samples. 5-Aza-2'-deoxycytidine treatment of lung cancer cell lines restored the mRNA expression levels of these 5 genes. Reduced mRNA expression in tumorous tissue samples was significantly correlated with tumor aggressiveness. These data suggest that DNA methylation alterations at precancerous stages determine tumor aggressiveness and outcome through silencing of specific genes.

Association of RASSF1A and p63 with poor recurrence-free survival in node-negative stage I-II non-small cell lung cancer

PURPOSE

This study was aimed at analyzing the recurrence-related prognostic significance of 12 candidate molecular biomarkers in node-negative stage I-II non-small cell lung cancer (NSCLC).

EXPERIMENTAL DESIGN

We retrospectively analyzed promoter methylation of eight genes using methylation-specific PCR in formalin-fixed and paraffin-embedded tissues from 328 node-negative stage I-II NSCLCs. The expression of Bcl-2, E-cadherin, p53, and p63 proteins was also assessed by immunohistochemistry.

RESULTS

Recurrence was found in 145 (44%) of 328 node-negative stage I-II NSCLCs with a median follow-up period of 6.2 years. No association was found between recurrence and alteration of individual biomarker in univariate analysis. We defined recurrently divergent groups on the basis of recursive partitioning analyses for 12 biomarkers and found a significant association of co-alteration of RASSF1A and p63 with poor recurrence-free survival (RFS). Cox proportional hazards analysis showed that hypermethylation of RASSF1A and negative expression of p63 was associated with poor RFS [HR, 1.93; 95% confidence interval (CI), 1.13-5.47; P = 0.009] compared with those without co-alteration of RASSF1A and p63, after adjusting for age, adjuvant therapy, histology, and tumor size. Random forest classifier including RASSF1A and p63 showed best performance in the prediction of recurrence in node-negative stage I-II NSCLCs: area under receiver operator characteristic curve for random forest was 0.91 and error rate for the model was 17%.

CONCLUSION

The present study suggests that RASSF1A and p63 may be independent prognostic indicators for RFS in node-negative stage I-II NSCLCs.

Aberrant genes promoter methylation in neural crest-derived tumors

Disturbances in the epigenetic landscape by aberrant methylation of CpG islands can lead to inactivation of cancer-related genes in solid tumors. We analyzed the promoter methylation status of 6 genes previously reported as cancer-specific methylated (MCAM, SSBP2, NISCH, B4GALT1, KIF1A and RASSF1A) in 38 neural crest-derived tumors by quantitative methylation-specific real-time PCR (QMSP). The results demonstrated that the determination of the methylation status of RASSF1A is able to distinguish between normal and tumor samples in cutaneous melanomas, lung carcinoids and small bowel carcinoids. MCAM methylation levels were significantly higher in lung carcinoids tumors (p=0.001), suggesting that this alteration may represent a molecular biomarker in this tumor type.