TSPAN8+ myofibroblastic cancer-associated fibroblasts promote chemoresistance in patients with breast cancer

Cancer-associated fibroblasts (CAFs) are abundant stromal cells in the tumor microenvironment that promote cancer progression and relapse. However, the heterogeneity and regulatory roles of CAFs underlying chemoresistance remain largely unclear. Here, we performed a single-cell analysis using high-dimensional flow cytometry analysis and identified a distinct senescence-like tetraspanin-8 (TSPAN8)+ myofibroblastic CAF (myCAF) subset, which is correlated with therapeutic resistance and poor survival in multiple cohorts of patients with breast cancer (BC). TSPAN8+ myCAFs potentiate the stemness of the surrounding BC cells through secretion of senescence-associated secretory phenotype (SASP)-related factors IL-6 and IL-8 to counteract chemotherapy. NAD-dependent protein deacetylase sirtuin 6 (SIRT6) reduction was responsible for the senescence-like phenotype and tumor-promoting role of TSPAN8+ myCAFs. Mechanistically, TSPAN8 promoted the phosphorylation of ubiquitin E3 ligase retinoblastoma binding protein 6 (RBBP6) at Ser772 by recruiting MAPK11, thereby inducing SIRT6 protein destruction. In turn, SIRT6 down-regulation up-regulated GLS1 and PYCR1, which caused TSPAN8+ myCAFs to secrete aspartate and proline, and therefore proved a nutritional niche to support BC outgrowth. By demonstrating that TSPAN8+SIRT6low myCAFs were tightly associated with unfavorable disease outcomes, we proposed that the combined regimen of anti-TSPAN8 antibody and SIRT6 activator MDL-800 is a promising approach to overcome chemoresistance. These findings highlight that senescence contributes to CAF heterogeneity and chemoresistance and suggest that targeting TSPAN8+ myCAFs is a promising approach to circumvent chemoresistance.

Resistance of HNSCC cell models to pan-FGFR inhibition depends on the EMT phenotype associating with clinical outcome

BACKGROUND

Focal adhesion signaling involving receptor tyrosine kinases (RTK) and integrins co-controls cancer cell survival and therapy resistance. However, co-dependencies between these receptors and therapeutically exploitable vulnerabilities remain largely elusive in HPV-negative head and neck squamous cell carcinoma (HNSCC).

METHODS

The cytotoxic and radiochemosensitizing potential of targeting 10 RTK and β1 integrin was determined in up to 20 3D matrix-grown HNSCC cell models followed by drug screening and patient-derived organoid validation. RNA sequencing and protein-based biochemical assays were performed for molecular characterization. Bioinformatically identified transcriptomic signatures were applied to patient cohorts.

RESULTS

Fibroblast growth factor receptor (FGFR 1-4) targeting exhibited the strongest cytotoxic and radiosensitizing effects as monotherapy and combined with β1 integrin inhibition, exceeding the efficacy of the other RTK studied. Pharmacological pan-FGFR inhibition elicited responses ranging from cytotoxicity/radiochemosensitization to resistance/radiation protection. RNA sequence analysis revealed a mesenchymal-to-epithelial transition (MET) in sensitive cell models, whereas resistant cell models exhibited a partial epithelial-to-mesenchymal transition (EMT). Accordingly, inhibition of EMT-associated kinases such as EGFR caused reduced adaptive resistance and enhanced (radio)sensitization to FGFR inhibition cell model- and organoid-dependently. Transferring the EMT-associated transcriptomic profiles to HNSCC patient cohorts not only demonstrated their prognostic value but also provided a conclusive validation of the presence of EGFR-related vulnerabilities that can be strategically exploited for therapeutic interventions.

CONCLUSIONS

This study demonstrates that pan-FGFR inhibition elicits a beneficial radiochemosensitizing and a detrimental radioprotective potential in HNSCC cell models. Adaptive EMT-associated resistance appears to be of clinical importance, and we provide effective molecular approaches to exploit this therapeutically.

Quantification of oxygen consumption in head and neck cancer using fluorescent sensor foil technology

Introduction

Head and neck squamous cell carcinoma (HNSCC) patients suffer from frequent local recurrences that negatively impact on prognosis. Hence, distinguishing tumor and normal tissue is of clinical importance as it may improve the detection of residual tumor tissue in surgical resection margins and during imaging-based surgery planning. Differences in O2 consumption (OC) can be used to this aim, as they provide options for improved surgical, image-guided approaches.

Methods

In the present study, the potential of a fluorescent sensor foil-based technology to quantify OC in HNSCC was evaluated in an in vitro 3D model and in situ in patients.

Results

In vitro measurements of OC using hypopharyngeal and esophageal cell lines allowed a specific detection of tumor cell spheroids embedded together with cancer-associated fibroblasts in type I collagen extracellular matrix down to a diameter of 440 µm. Pre-surgery in situ measurements were conducted with a handheld recording device and sensor foils with an oxygen permeable membrane and immobilized O2-reactive fluorescent dyes. Lateral tongue carcinoma and carcinoma of the floor of the mouth were chosen for analysis owing to their facilitated accessibility. OC was evaluated over a time span of 60 seconds and was significantly higher in tumor tissue compared to healthy mucosa in the vicinity of the tumor.

Discussion

Hence, OC quantification using fluorescent sensor foil-based technology is a relevant parameter for the differentiation of tumor tissue of the head and neck region and may support surgery planning.

Longitudinal detection of subcategorized CD44v6+ CTCs and circulating tumor endothelial cells (CTECs) enables novel clinical stratification and improves prognostic prediction of small cell lung cancer: A prospective, multi-center study

Current management of small cell lung cancer (SCLC) remains challenging. Effective biomarkers are needed to subdivide patients presenting distinct treatment response and clinical outcomes. An understanding of heterogeneous phenotypes of aneuploid CD31- circulating tumor cells (CTCs) and CD31+ circulating tumor endothelial cells (CTECs) may provide novel insights in the clinical management of SCLC. In the present translational and prospective study, increased cancer metastasis-related cell proliferation and motility, accompanied with up-regulated mesenchymal marker vimentin but down-regulated epithelial marker E-cadherin, were observed in both lentivirus infected SCLC and NSCLC cells overexpressing the stemness marker CD44v6. Aneuploid CTCs and CTECs expressing CD44v6 were longitudinally detected by SE-iFISH in 120 SCLC patients. Positive detection of baseline CD44v6+ CTCs and CD44v6+ CTECs was significantly associated with enhanced hepatic metastasis. Karyotype analysis revealed that chromosome 8 (Chr8) in CD44v6+ CTCs shifted from trisomy 8 towards multiploidy in post-therapeutic patients compared to pre-treatment subjects. Furthermore, the burden of baseline CD44v6+ CTCs (t0) or amid the therapy (t1-2), the ratio of baseline CD31+ CTEC/CD31- CTC (t0), and CTC-WBC clusters (t0) were correlated with treatment response and distant metastases, particularly brain metastasis, in subjects with limited disease (LD-SCLC) but not in those with extensive disease (ED-SCLC). Multivariate survival analysis validated that longitudinally detected CD44v6+/CD31- CTCs was an independent prognostic factor for inferior survival in SCLC patients. Our study provides evidence for the first time that comprehensive analyses of CTCs, CTECs, and their respective CD44v6+ subtypes enable clinical stratification and improve prognostic prediction of SCLC, particularly for potentially curable LD-SCLC.

5'-Ectonucleotidase CD73/NT5E supports EGFR-mediated invasion of HPV-negative head and neck carcinoma cells

BACKGROUND

Epithelial-to-mesenchymal transition (EMT) of malignant cells is a driving force of disease progression in human papillomavirus-negative (HPV-negative) head and neck squamous cell carcinomas (HNSCC). Sustained hyper-activation of epidermal growth factor receptor (EGFR) induces an invasion-promoting subtype of EMT (EGFR-EMT) characterized by a gene signature ("'EGFR-EMT_Signature'") comprising 5´-ectonucleotidase CD73. Generally, CD73 promotes immune evasion via adenosine (ADO) formation and associates with EMT and metastases. However, CD73 regulation through EGFR signaling remains under-explored and targeting options are amiss.

METHODS

CD73 functions in EGFR-mediated tumor cell dissemination were addressed in 2D and 3D cellular models of migration and invasion. The novel antagonizing antibody 22E6 and therapeutic antibody Cetuximab served as inhibitors of CD73 and EGFR, respectively, in combinatorial treatment. Specificity for CD73 and its role as effector or regulator of EGFR-EMT were assessed upon CD73 knock-down and over-expression. CD73 correlation to tumor budding was studied in an in-house primary HNSCC cohort. Expression correlations, and prognostic and predictive values were analyzed using machine learning-based algorithms and Kaplan-Meier survival curves in single cell and bulk RNA sequencing datasets.

RESULTS

CD73/NT5E is induced by the EGF/EGFR-EMT-axis and blocked by Cetuximab and MEK inhibitor. Inhibition of CD73 with the novel antagonizing antibody 22E6 specifically repressed EGFR-dependent migration and invasion of HNSCC cells in 2D. Cetuximab and 22E6 alone reduced local invasion in a 3D-model. Interestingly, combining inefficient low-dose concentrations of Cetuximab and 22E6 revealed highly potent in invasion inhibition, substantially reducing the functional IC50 of Cetuximab regarding local invasion. A role for CD73 as an effector of EGFR-EMT in local invasion was further supported by knock-down and over-expression experiments in vitro and by high expression in malignant cells budding from primary tumors. CD73 expression correlated with EGFR pathway activity, EMT, and partial EMT (p-EMT) in malignant single HNSCC cells and in large patient cohorts. Contrary to published data, CD73 was not a prognostic marker of overall survival (OS) in the TCGA-HNSCC cohort when patients were stratified for HPV-status. However, CD73 prognosticated OS of oral cavity carcinomas. Furthermore, CD73 expression levels correlated with response to Cetuximab in HPV-negative advanced, metastasized HNSCC patients.

CONCLUSIONS

In sum, CD73 is an effector of EGF/EGFR-mediated local invasion and a potential therapeutic target and candidate predictive marker for advanced HPV-negative HNSCC.

A transcriptomic pan-cancer signature for survival prognostication and prediction of immunotherapy response based on endothelial senescence

BACKGROUND

The microvascular endothelium inherently controls nutrient delivery, oxygen supply, and immune surveillance of malignant tumors, thus representing both biological prerequisite and therapeutic vulnerability in cancer. Recently, cellular senescence emerged as a fundamental characteristic of solid malignancies. In particular, tumor endothelial cells have been reported to acquire a senescence-associated secretory phenotype, which is characterized by a pro-inflammatory transcriptional program, eventually promoting tumor growth and formation of distant metastases. We therefore hypothesize that senescence of tumor endothelial cells (TEC) represents a promising target for survival prognostication and prediction of immunotherapy efficacy in precision oncology.

METHODS

Published single-cell RNA sequencing datasets of different cancer entities were analyzed for cell-specific senescence, before generating a pan-cancer endothelial senescence-related transcriptomic signature termed EC.SENESCENCE.SIG. Utilizing this signature, machine learning algorithms were employed to construct survival prognostication and immunotherapy response prediction models. Machine learning-based feature selection algorithms were applied to select key genes as prognostic biomarkers.

RESULTS

Our analyses in published transcriptomic datasets indicate that in a variety of cancers, endothelial cells exhibit the highest cellular senescence as compared to tumor cells or other cells in the vascular compartment of malignant tumors. Based on these findings, we developed a TEC-associated, senescence-related transcriptomic signature (EC.SENESCENCE.SIG) that positively correlates with pro-tumorigenic signaling, tumor-promoting dysbalance of immune cell responses, and impaired patient survival across multiple cancer entities. Combining clinical patient data with a risk score computed from EC.SENESCENCE.SIG, a nomogram model was constructed that enhanced the accuracy of clinical survival prognostication. Towards clinical application, we identified three genes as pan-cancer biomarkers for survival probability estimation. As therapeutic perspective, a machine learning model constructed on EC.SENESCENCE.SIG provided superior pan-cancer prediction for immunotherapy response than previously published transcriptomic models.

CONCLUSIONS

We here established a pan-cancer transcriptomic signature for survival prognostication and prediction of immunotherapy response based on endothelial senescence.

Isolation and characterization of head and neck cancer-derived peritumoral and cancer-associated fibroblasts

Introduction

Head and neck squamous cell carcinomas (HNSCC) are characterized by strong cellular and molecular heterogeneity and treatment resistance entailing poor survival. Besides cell-intrinsic properties, carcinoma cells receive important cues from non-malignant cells within the tumor microenvironment (TME). Cancer-associated fibroblasts (CAFs) are a major component of the TME that impact on the molecular make-up of malignant cells and have a decisive function in tumor progression. However, the potential functionality of fibroblasts within tumor-adjacent, macroscopically normal tissue remains poorly explored.

Methods

Here, we isolated primary peritumoral fibroblasts (PtFs) from macroscopically normal tissue in vicinity of primary human papillomavirus-negative and -positive oropharyngeal HNSCC and compared their phenotype and functionality with matched CAFs (n = 5 pairs) and with human oral fibroblasts (hOFs).

Results

Expression patterns of CD90, CD73, CD105, smooth muscle actin, Vimentin, and S100A4 were comparable in PtFs, CAFs, and hOFs. Cell proliferation and doubling times of CAFs and PtFs were heterogeneous across patients (n =2 PtF>CAF; n = 1 CAF>PtF; n = 2 CAF=PtF) and reflected inferior growth than hOFs. Furthermore, PtFs displayed an reduced heterogeneity in cell size compared to matched CAFs, which were characterized by the presence of single large cells. Overall, conditioned supernatants from CAFs had more frequently growth-promoting effects on a panel of carcinoma cell lines of the upper aerodigestive tract carcinoma cell lines (Cal27, Cal33, FaDu, and Kyse30), whereas significant differences in migration-inducing effects demonstrated a higher potential of PtFs. Except for Kyse30, CAFs were significantly superior to hOFs in promoting proliferation, while PtFs induced stronger migration than hOFs in all carcinoma lines tested. Analysis of soluble factors demonstrated significantly increased VEGF-A production in CAFs (except in pat.8), and significantly increased PDGF-BB production in PtFs of two patients. Tube formation assays confirmed a significantly enhanced angiogenic potential of conditioned supernatants from CAFs compared to hOFs on human umbilical vascular endothelial cells (HUVECs) in vitro.

Discussion

Hence, matched CAFs and PtFs present in HNSCC patients are heterogeneous in their proliferation-, migration-, and angiogenesis-promoting capacity. Despite this heterogeneity, CAFs induced stronger carcinoma cell proliferation and HUVEC tube formation overall, whereas PtFs promoted migration of tumor cells more strongly.

A transcriptomic map of EGFR-induced epithelial-to-mesenchymal transition identifies prognostic and therapeutic targets for head and neck cancer

Background

Epidermal growth factor receptor (EGFR) is both a driver oncogene and a therapeutic target in advanced head and neck squamous cell carcinoma (HNSCC). However, response to EGFR treatment is inconsistent and lacks markers for treatment prediction. This study investigated EGFR-induced epithelial-to-mesenchymal transition (EMT) as a central parameter in tumor progression and identified novel prognostic and therapeutic targets, and a candidate predictive marker for EGFR therapy response.

Methods

Transcriptomic profiles were analyzed by RNA sequencing (RNA-seq) following EGFR-mediated EMT in responsive human HNSCC cell lines. Exclusive genes were extracted via differentially expressed genes (DEGs) and a risk score was determined through forward feature selection and Cox regression models in HNSCC cohorts. Functional characterization of selected prognostic genes was conducted in 2D and 3D cellular models, and findings were validated by immunohistochemistry in primary HNSCC.

Results

An EGFR-mediated EMT gene signature composed of n = 171 genes was identified in responsive cell lines and transferred to the TCGA-HNSCC cohort. A 5-gene risk score comprising DDIT4, FADD, ITGB4, NCEH1, and TIMP1 prognosticated overall survival (OS) in TCGA and was confirmed in independent HNSCC cohorts. The EGFR-mediated EMT signature was distinct from EMT hallmark and partial EMT (pEMT) meta-programs with a differing enrichment pattern in single malignant cells. Molecular characterization showed that ITGB4 was upregulated in primary tumors and metastases compared to normal mucosa and correlated with EGFR/MAPK activity in tumor bulk and single malignant cells. Preferential localization of ITGB4 together with its ligand laminin 5 at tumor-stroma interfaces correlated with increased tumor budding in primary HNSCC tissue sections. In vitro, ITGB4 knock-down reduced EGFR-mediated migration and invasion and ITGB4-antagonizing antibody ASC8 impaired 2D and 3D invasion. Furthermore, a logistic regression model defined ITGB4 as a predictive marker of progression-free survival in response to Cetuximab in recurrent metastatic HNSCC patients.

Conclusions

EGFR-mediated EMT conveyed through MAPK activation contributes to HNSCC progression upon induction of migration and invasion. A 5-gene risk score based on a novel EGFR-mediated EMT signature prognosticated survival of HNSCC patients and determined ITGB4 as potential therapeutic and predictive target in patients with strong EGFR-mediated EMT.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12943-022-01646-1.

Liquid BIOpsy for MiNimal RESidual DiSease Detection in Head and Neck Squamous Cell Carcinoma (LIONESS)-a personalised circulating tumour DNA analysis in head and neck squamous cell carcinoma

BACKGROUND

Head and neck squamous cell carcinoma (HNSCC) remain a substantial burden to global health. Cell-free circulating tumour DNA (ctDNA) is an emerging biomarker but has not been studied sufficiently in HNSCC.

METHODS

We conducted a single-centre prospective cohort study to investigate ctDNA in patients with p16-negative HNSCC who received curative-intent primary surgical treatment. Whole-exome sequencing was performed on formalin-fixed paraffin-embedded (FFPE) tumour tissue. We utilised RaDaR^TM, a highly sensitive personalised assay using deep sequencing for tumour-specific variants, to analyse serial pre- and post-operative plasma samples for evidence of minimal residual disease and recurrence.

RESULTS

In 17 patients analysed, personalised panels were designed to detect 34 to 52 somatic variants. Data show ctDNA detection in baseline samples taken prior to surgery in 17 of 17 patients. In post-surgery samples, ctDNA could be detected at levels as low as 0.0006% variant allele frequency. In all cases with clinical recurrence to date, ctDNA was detected prior to progression, with lead times ranging from 108 to 253 days.

CONCLUSIONS

This study illustrates the potential of ctDNA as a biomarker for detecting minimal residual disease and recurrence in HNSCC and demonstrates the feasibility of personalised ctDNA assays for the detection of disease prior to clinical recurrence.

Therapy-related transcriptional subtypes in matched primary and recurrent head and neck cancer

PURPOSE

The genetic relatedness between primary and recurrent head and neck squamous cell carcinomas (HNSCC) reflects the extent of heterogeneity and therapy-driven selection of tumor subpopulations. Yet, current treatment of recurrent HNSCC ignores the molecular characteristics of therapy-resistant tumor populations.

EXPERIMENTAL DESIGN

From 150 tumors, 74 primary HNSCCs were RNA-sequenced and 38 matched primary/recurrent tumor pairs were both, whole-exome and RNA-sequenced. Transcriptome analysis determined the predominant classical (CL), basal (BA) and inflamed-mesenchymal (IMS) transcriptional subtypes according to an established classification. Genomic alterations and clonal compositions of tumors were evaluated from whole-exome data.

RESULTS

While CL and IMS subtypes were more common in primary HNSCC with low recurrence rates, the BA subtype was more prevalent and stable in recurrent tumors. The BA subtype was associated with a transcriptional signature of partial epithelial-to-mesenchymal transition (p-emt) and early recurrence. In 44% of matched cases, the dominant subtype changed from primary to recurrent tumors, preferably from IMS to BA or CL. Gene set enrichment analysis identified upregulation of Hypoxia, p-emt and radiation resistance signatures and downregulation of tumor inflammation in recurrences compared to index tumors. A relevant subset of primary/recurrent tumor pairs presented no evidence for a common clonal origin.

CONCLUSIONS

Our study showed a high degree of genetic and transcriptional heterogeneity between primary/recurrent tumors, suggesting therapy-related selection of a transcriptional subtype with characteristics unfavorable for therapy. We conclude that therapy decisions should be based on genetic and transcriptional characteristics of recurrences rather than primary tumors to enable optimally tailored treatment strategies.

Uncoupled biological and chronological aging of neutrophils in cancer promotes tumor progression

Background

Beyond their fundamental role in homeostasis and host defense, neutrophilic granulocytes (neutrophils) are increasingly recognized to contribute to the pathogenesis of malignant tumors. Recently, aging of mature neutrophils in the systemic circulation has been identified to be critical for these immune cells to properly unfold their homeostatic and anti-infectious functional properties. The role of neutrophil aging in cancer remains largely obscure.

Methods

Employing advanced in vivo microscopy techniques in different animal models of cancer as well as utilizing pulse-labeling and cell transfer approaches, various ex vivo/in vitro assays, and human data, we sought to define the functional relevance of neutrophil aging in cancer.

Results

Here, we show that signals released during early tumor growth accelerate biological aging of circulating neutrophils, hence uncoupling biological from chronological aging of these immune cells. This facilitates the accumulation of highly reactive neutrophils in malignant lesions and endows them with potent protumorigenic functions, thus promoting tumor progression. Counteracting uncoupled biological aging of circulating neutrophils by blocking the chemokine receptor CXCR2 effectively suppressed tumor growth.

Conclusions

Our data uncover a self-sustaining mechanism of malignant neoplasms in fostering protumorigenic phenotypic and functional changes in circulating neutrophils. Interference with this aberrant process might therefore provide a novel, already pharmacologically targetable strategy for cancer immunotherapy.

Interactome analysis reveals endocytosis and membrane recycling of EpCAM during differentiation of embryonic stem cells and carcinoma cells

Transmembrane epithelial cell adhesion molecule (EpCAM) is expressed in epithelia, carcinoma, teratoma, and embryonic stem cells (ESCs). EpCAM displays spatiotemporal patterning during embryogenesis, tissue morphogenesis, cell differentiation, and epithelial-to-mesenchymal transition (EMT) in carcinomas. Potential interactors of EpCAM were identified in murine F9 teratoma cells using a stable isotope labeling with amino acids in cell culture-based proteomic approach (n = 77, enrichment factor >3, p value ≤ 0.05). Kyoto Encyclopedia of Genes and Genomes and gene ontology terms revealed interactions with regulators of endosomal trafficking and membrane recycling, which were further validated for Rab5, Rab7, and Rab11. Endocytosis and membrane recycling of EpCAM were confirmed in mF9 cells, E14TG2α ESC, and Kyse30 carcinoma cells. Reduction of EpCAM during mesodermal differentiation and TGFβ-induced EMT correlated with enhanced endocytosis and block or reduction of recycling in ESCs and esophageal carcinoma cells. Hence, endocytosis and membrane recycling are means of regulation of EpCAM protein levels during differentiation of ESC and EMT induction in carcinoma cells.

Role of aneuploid circulating tumor cells and CD31+ circulating tumor endothelial cells in predicting and monitoring anti-angiogenic therapy efficacy in advanced NSCLC

Prognosticating the efficacy of anti‐angiogenic therapy through longitudinal monitoring and early detection of treatment resistance in cancer patients remain highly challenging. In this study, co‐detection and comprehensive phenotypic and karyotypic molecular characterization of aneuploid circulating tumor cells (CTCs) and circulating tumor endothelial cells (CTECs) were conducted on non‐small cell lung cancer (NSCLC) patients receiving bevacizumab plus chemotherapy. Prognostic values of the cell‐based significant univariate risk factors identified by Cox regression analyses were progressively investigated. Subjects showing an increase in total post‐therapeutic platelet endothelial cell adhesion molecule‐1 (CD31)^– CTCs and CD31⁺ CTECs exhibited a significantly reduced median progression‐free survival (mPFS) and overall survival. Further stratification analyses indicated that pretherapeutic patients bearing vimentin (Vim)⁺ CTECs (mesenchymal M‐type) at baseline revealed a significantly shortened mPFS compared with patients with Vim^– CTECs. Post‐therapeutic patients harboring epithelial cell adhesion molecule (EpCAM)⁺ CTCs and CTECs (epithelial E‐type), regardless of Vim expression or not, showed a significantly reduced mPFS. Post‐therapeutic patients possessing de novo EpCAM⁺/Vim⁺ (hybrid E/M‐type) CTECs displayed the shortest mPFS. Patients harboring either pre‐ or post‐therapeutic EpCAM^–/Vim^– null CTECs (N‐type) exhibited a better response to therapy compared to patients harboring EpCAM⁺ and/or Vim⁺ CTECs. The presented results support the notion that baseline Vim⁺ CTECs and post‐therapeutic EpCAM⁺ CTCs and CTECs are predictive biomarkers for longitudinal monitoring of response to anti‐angiogenesis combination regimens in NSCLC patients.

SLUG-related partial epithelial-to-mesenchymal transition is a transcriptomic prognosticator of head and neck cancer survival

Partial epithelial‐to‐mesenchymal transition (pEMT) contributes to cellular heterogeneity that is associated with nodal metastases and unfavorable clinical parameters in head and neck squamous cell carcinomas (HNSCCs). We developed a single‐cell RNA sequencing signature‐based pEMT quantification through cell type‐dependent deconvolution of bulk RNA sequencing and microarray data combined with single‐sample scoring of molecular phenotypes (Singscoring). Clinical pEMT‐Singscores served as molecular classifiers in multivariable Cox proportional hazard models and high scores prognosticated poor overall survival and reduced response to irradiation as independent parameters in large HNSCC cohorts [The Cancer Genome Atlas (TCGA), MD Anderson Cancer Centre (MDACC), Fred Hutchinson Cancer Research Center (FHCRC)]. Differentially expressed genes confirmed enhanced cell motility and reduced oxidative phosphorylation and epithelial differentiation in pEMT^high patients. In patients and cell lines, the EMT transcription factor SLUG correlated most strongly with pEMT‐Singscores and promoted pEMT, enhanced invasion, and resistance to irradiation in vitro. SLUG protein levels in HNSCC predicted disease‐free survival, and its peripheral expression at the interphase to the tumor microenvironment was significantly increased in relapsing patients. Hence, pEMT‐Singscores represent a novel risk predictor for HNSCC stratification regarding clinical outcome and therapy response that is partly controlled by SLUG.

Abstract 553: Personalized circulating tumor DNA analysis in head and neck squamous cell carcinoma: Preliminary results of the Liquid BIOpsy for MiNimal RESidual DiSease Detection in Head and NeckSquamous Cell Carcinoma (LIONESS) study

Introduction

Head and neck squamous cell carcinoma (HNSCC) remains a substantial burden to global health. Despite evolving therapies, 5-year survival is less than 50% and unlike other cancers, reliable biomarkers to monitor treatment response do not exist. Cell-free circulating tumor DNA (ctDNA) is an emerging biomarker but has not yet been studied sufficiently for HNSCC. The detection of ctDNA as a marker of minimal residual disease following curative-intent treatment holds promise for identifying patients at an increased risk of relapse, who may benefit from adjuvant radio(chemo)therapy or facilitate close monitoring with repeat resection if needed.

Methods

We conducted a single-center prospective experimental evidence-generating cohort study to assess ctDNA in 30 patients with p16-negative HNSCC (stages I-IVB) who received primary surgical treatment with curative intent at our institution. Whole exome sequencing (WES) was performed on formalin-fixed paraffin-embedded tumor tissue to a median depth of 250x. For each patient, we selected up to 48 somatic variants for personalized ctDNA assay design. We used the RaDaRTM assay to analyze serial pre- and post-operative plasma samples (range 2-6) for evidence of minimal residual disease or recurrence.

Results

In a subset of patients analyzed to evaluate the performance of RaDaR, personalized panels were designed with between 34 and 48 somatic variants (median 48). Preliminary data shows 100% ctDNA detection in baseline samples taken prior to surgery at tumor fractions ranging from 312 ppm (equivalent to 0.03% AF) to 7579 ppm (equivalent to 0.76% AF). In post-surgery samples, ctDNA could be detected at levels as low as 26 ppm (equivalent to 0.0026% AF). Analysis of follow-up plasma samples will be presented along with data from the full patient cohort.

Conclusions

This study illustrates the potential of ctDNA as a biomarker in HNSCC and demonstrates the feasibility of personalized ctDNA assays for the detection of minimal residual disease post-treatment and for monitoring for early detection of relapse.

Citation Format: Susanne Flach, Karen Howarth, Sophie Hackinger, Christodoulos Pipinikas, Kirsten McLay, Giovanni Marsico, Christoph Walz, Olivier Gires, Martin Canis, Philipp Baumeister. Personalized circulating tumor DNA analysis in head and neck squamous cell carcinoma: Preliminary results of the Liquid BIOpsy for MiNimal RESidual DiSease Detection in Head and NeckSquamous Cell Carcinoma (LIONESS) study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 553.

High-resolution spatiotemporal pHe and pO2 imaging in head and neck and oesophageal carcinoma cells

Background

pO₂ and pH are physiological parameters relevant for different processes in health and disease, including wound healing and cancer progression. Head and neck squamous cell carcinomas (HNSCC) and oesophageal squamous cell carcinomas (ESCC) have a high rate of local recurrence that is partly related to treatment-resistant residual tumour cells. Hence, novel diagnostic tools are required to visualise potential residual tumour cells and thereby improve treatment outcome for HNSCC and ESCC patients. We developed a device to spatiotemporally measure oxygen consumption rates (OCR) and extracellular acidification rates (ECAR) to distinguish HNSCC and ESCC cells from healthy cells in vitro, exploiting general metabolic differences between cancer cells and healthy cells.

Methods

OCR and ECAR were measured via a newly developed device named STO₂p-Q (SpatioTemporal O₂ and pH Quantification) using the VisiSens technology based on ratiometric fluorescence imaging, facilitating spatiotemporal resolution. Results were confirmed using extracellular flux analyses (Seahorse technology).

Results

STO₂p-Q is described and used to measure OCR and ECAR in HNSCC and ESCC cell lines and normal fibroblast and epithelial cells as components of the tumour microenvironment. OCR measurements showed differences amongst HNSCC and ESCC cell lines and between HNSCC/ESCC and normal cells, which on average had lower OCR than HNSCC/ESCC cells. Both OCR and ECAR measurements were independently verified using the Seahorse technology. Additionally, using STO₂p-Q, HNSCC/ESCC, and normal cells could be spatially resolved with a resolution in the low millimetre range.

Conclusions

We developed a method to spatiotemporally measure OCR and ECAR of cells, which has many potential in vitro applications and lays the foundation for the development of novel diagnostic tools for the detection of cancerous tissue in HNSCC and ESCC patients in vivo.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40170-021-00257-6.

Prevalence and reclassification of BRCA1 and BRCA2 variants in a large, unselected Chinese Han breast cancer cohort

Accurate interpretation of BRCA1/2 variants is critical for risk assessment and precise treatment of breast cancer (BC). Hence, the establishment of an ethnicity-based BRCA1/2 variant database of the Chinese population is of paramount importance. In this study, panel-based sequencing served to detect BRCA1/2 variants in a Chinese multicenter cohort of 21,216 BC patients and 6434 healthy controls. Overall, the percentage of subjects carrying pathogenic variants was 5.5% (1174/21,216) in BC patients and 1.1% (71/6434) in healthy controls. We identified 13 pathogenic variants as high-frequency variants that had a frequency of > 0.45‰ in BC patients (≥ 10 in 21,216 patients), none of which has been reported in Caucasians. Pathogenic BRCA1/2 variants correlated with younger onset age, higher frequencies of bilateral and triple-negative BC (TNBC), invasive carcinomas, high histological grades, and family history of BC and other cancers. Furthermore, the percentage of the subjects carrying VUS was 9.8% (2071/21,216) in BC patients and 6.9% (446/6434) in healthy controls. Based on our cohort study, we unambiguously reclassified 7 out of the 858 VUS resulting in lower VUS ratio in patients (from 9.8 to 7.9%) as well as in healthy control (from 6.9 to 5.3%). We also re-analyzed the 100 variants in 13 exons (2–5 and 15–23) of the BRCA1 genes using a functional assay (saturation genome editing; SGE). 55 of the 59 VUS had distinct status in the SGE study: 24 (43.6%) were pathogenic, and 31 (56.4%) were benign. Strong ethnicity-specific occurrences of pathogenic BRCA1/2 variants were identified in the Chinese population. Hence, the findings provide rationale and sequencing information for the implementation of BRCA1/2 variants tailored to the Chinese population into clinical risk assessment.

Digital scoring of EpCAM and slug expression as prognostic markers in head and neck squamous cell carcinomas

Head and neck squamous cell carcinomas (HNSCCs) have poor clinical outcome owing to therapy resistance and frequent recurrences that are among others attributable to tumor cells in partial epithelial‐to‐mesenchymal transition (pEMT). We compared side‐by‐side software‐based and visual quantification of immunohistochemistry (IHC) staining of epithelial marker EpCAM and EMT regulator Slug in n = 102 primary HNSCC to assess optimal analysis protocols. IHC scores incorporated expression levels and percentages of positive cells. Digital and visual evaluation of membrane‐associated EpCAM yielded correlating scorings, whereas visual evaluation of nuclear Slug resulted in significantly higher overall scores. Multivariable Cox proportional hazard analysis defined the median EpCAM expression levels resulting from visual quantification as an independent prognostic factor of overall survival. Slug expression levels resulting from digital quantification were an independent prognostic factor of recurrence‐free survival, locoregional recurrence‐free survival, and disease‐specific survival. Hence, we propose to use visual assessment for the membrane‐associated EpCAM protein, whereas nuclear protein Slug assessment was more accurate following digital measurement.

Expression and function of epithelial cell adhesion molecule EpCAM: where are we after 40 years?

EpCAM (epithelial cell adhesion molecule) was discovered four decades ago as a tumor antigen on colorectal carcinomas. Owing to its frequent and high expression on carcinomas and their metastases, EpCAM serves as a prognostic marker, a therapeutic target, and an anchor molecule on circulating and disseminated tumor cells (CTCs/DTCs), which are considered the major source for metastatic cancer cells. Today, EpCAM is reckoned as a multi-functional transmembrane protein involved in the regulation of cell adhesion, proliferation, migration, stemness, and epithelial-to-mesenchymal transition (EMT) of carcinoma cells. To fulfill these functions, EpCAM is instrumental in intra- and intercellular signaling as a full-length molecule and following regulated intramembrane proteolysis, generating functionally active extra- and intracellular fragments. Intact EpCAM and its proteolytic fragments interact with claudins, CD44, E-cadherin, epidermal growth factor receptor (EGFR), and intracellular signaling components of the WNT and Ras/Raf pathways, respectively. This plethora of functions contributes to shaping intratumor heterogeneity and partial EMT, which are major determinants of the clinical outcome of carcinoma patients. EpCAM represents a marker for the epithelial status of primary and systemic tumor cells and emerges as a measure for the metastatic capacity of CTCs. Consequentially, EpCAM has reclaimed potential as a prognostic marker and target on primary and systemic tumor cells.

Safety and Efficacy of Blue Light Laser Treatment in Hereditary Hemorrhagic Telangiectasia

BACKGROUND AND OBJECTIVES

Hereditary hemorrhagic telangiectasia (HHT) is a hereditary condition that is associated with arteriovenous malformations. A common site for these malformations is the nasal mucosa, which is associated with severe epistaxis and debilitation for affected patients. We evaluated the efficacy and safety of blue light laser technology in treating these endonasal manifestations in a retrospective chart analysis. Additionally, we compared blue light laser technology to bipolar coagulation in an animal model.

STUDY DESIGN/MATERIALS AND METHODS

We performed a retrospective chart analysis of all patients that were diagnosed with HHT and received endonasal blue light laser treatment between 10/2017 and 04/2019. In addition, we performed bipolar or blue light laser coagulation of all macroscopically visible vessels on thyroid gland lobes (n = 4) from Dunkin-Hartley Guinea Pigs. Hematoxylin-eosin (HE) staining was then used to visualize depth and area of coagulation surrounding these vessels.

RESULTS

One hundred and fifty-one treatments in 23 patients were analyzed. Under regular blue light laser treatment, quality of life (QOL), indicated on a visual analog scale from 1 to 10, gradually increased significantly from 5.6 ± 0.5 (before the first treatment) to 7.5 ± 0.9 (after the second treatment). Following this, QOL remained steady throughout additional treatments. Adverse effects were not recorded. HE staining showed that coagulation depth (162 ± 56 vs. 586 ± 192 µm) and area (74 ± 35 vs. 1015 ± 449 µm² ) were significantly lower after laser treatment.

CONCLUSION

Blue light laser therapy is safe and efficient in treating HHT. Damage to the surrounding tissue is significantly lower compared with bipolar coagulation. © 2020 The Authors. Lasers in Surgery and Medicine published by Wiley Periodicals LLC.

Cigarette Smoke Reduces the Efficacy of Cisplatin in Head and Neck Cancer Cells - Role of ABCG2

BACKGROUND/AIM

We evaluated the influence of smoking on head and neck squamous cell carcinomas (HNSCC), which are in their majority tobacco-driven. Tobacco smoke is expected to influence the expression of ABCG2-transporters involved in multidrug resistance. The aim of the study was to evaluate the effect of cigarette smoke condensate (CSC) on ABCG2 expression on HNSCC cells, to demonstrate the adverse effects of cigarette smoke during anticancer treatment in vitro and to assess the prevalence of ABCG2 expression in HNSCC.

MATERIALS AND METHODS

HNSCC cell lines were treated with CSC and basal and induced ABCG2 expression was examined. The impact of CSC on cellular viability/proliferation during cytotoxic drug treatment was also evaluated. ABCG2 expression levels in HNSCC were correlated with the smoking history of patients.

RESULTS

HNSCC cells showed low basal ABCG2 expression. CSC treatment resulted in a threefold increase in the expression of ABCG2 and in resistance to cisplatin. Tumor samples of never smokers showed significantly higher ABCG2 expression compared to ever smokers. ABCG2 expression correlated with pack years of cigarette consumption.

CONCLUSION

Tobacco consumption is linked to an inducible and increased ABCG2 protein expression and has an impact on drug resistance.

Molecular Characterization of Lipoaspirates Used in Regenerative Head and Neck Surgery

Importance

Adipose-derived mesenchymal stem cells (ASCs) have been used commonly in regenerative medicine and increasingly for head and neck surgical procedures. Lipoaspiration with centrifugation is purported to be a mild method for the extraction of ASCs used for autologous transplants to restore tissue defects or induce wound healing. The content of ASCs, their paracrine potential, and cellular potential in wound healing have not been explored for this method to our knowledge.

Objective

To evaluate the characteristics of lipoaspirates used in reconstructive head and neck surgical procedures with respect to wound healing.

Design, Setting, and Participants

This case series study included 15 patients who received autologous fat injections in the head and neck during surgical procedures at a tertiary referral center. The study was performed from October 2017 to November 2018, and data were analyzed from October 2017 to February 2019.

Main Outcomes and Measures

Excessive material of lipoaspirates from subcutaneous abdominal fatty tissue was examined. Cellular composition was analyzed using immunohistochemistry (IHC) and flow cytometry, and functionality was assessed through adipose, osteous, and chondral differentiation in vitro. Supernatants were tested for paracrine ASC functions in fibroblast wound-healing assays. Enzyme-linked immunosorbent assay measurement of tumor necrosis factor (TNF), vascular endothelial growth factor (VEGF), stromal-derived factor 1α (SDF-1α), and transforming growth factor β3 (TGF-β3) was performed.

Results

Among the 15 study patients (8 [53.3%] male; mean [SD] age at the time of surgery, 63.0 [2.8] years), the stromal vascular fraction (mean [SE], 53.3% [4.2%]) represented the largest fraction within the native lipoaspirates. The cultivated cells were positive for CD73 (mean [SE], 99.90% [0.07%]), CD90 (99.40% [0.32%]), and CD105 (88.54% [2.74%]); negative for CD34 (2.70% [0.45%]) and CD45 (1.74% [0.28%]) in flow cytometry; and negative for CD14 (10.56 [2.81] per 300 IHC score) and HLA-DR (6.89 [2.97] per 300 IHC score) in IHC staining; they differentiated into osteoblasts, adipocytes, and chondrocytes. The cultivated cells showed high expression of CD44 (mean [SE], 99.78% [0.08%]) and CD273 (82.56% [5.83%]). The supernatants were negative for TNF (not detectable) and SDF-1α (not detectable) and were positive for VEGF (mean [SE], 526.74 [149.84] pg/mL for explant supernatants; 528.26 [131.79] pg/106 per day for cell culture supernatants) and TGF-β3 (mean [SE], 22.79 [3.49] pg/mL for explant supernatants; 7.97 [3.15] pg/106 per day for cell culture supernatants). Compared with control (25% or 50% mesenchymal stem cell medium), fibroblasts treated with ASC supernatant healed the scratch-induced wound faster (mean [SE]: control, 1.000 [0.160]; explant supernatant, 1.369 [0.070]; and passage 6 supernatant, 1.492 [0.094]).

Conclusions and Relevance

The cells fulfilled the international accepted criteria for mesenchymal stem cells. The lipoaspirates contained ASCs that had the potential to multidifferentiate with proliferative and immune-modulating properties. The cytokine profile of the isolated ASCs had wound healing-promoting features. Lipoaspirates may have a regenerative potential and an application in head and neck surgery.

Level of Evidence

NA.

Epithelial-type systemic breast carcinoma cells with a restricted mesenchymal transition are a major source of metastasis

Carcinoma cells undergo epithelial-mesenchymal transition (EMT); however, contributions of EMT heterogeneity to disease progression remain a matter of debate. Here, we addressed the EMT status of ex vivo cultured circulating and disseminated tumor cells (CTCs/DTCs) in a syngeneic mouse model of metastatic breast cancer (MBC). Epithelial-type CTCs with a restricted mesenchymal transition had the strongest lung metastases formation ability, whereas mesenchymal-type CTCs showed limited metastatic ability. EpCAM expression served as a surrogate marker to evaluate the EMT heterogeneity of clinical samples from MBC, including metastases, CTCs, and DTCs. The proportion of epithelial-type CTCs, and especially DTCs, correlated with distant metastases and poorer outcome of patients with MBC. This study fosters our understanding of EMT in metastasis and underpins heterogeneous EMT phenotypes as important parameters for tumor prognosis and treatment. We further suggest that EpCAM-dependent CTC isolation systems will underestimate CTC numbers but will quantify clinically relevant metastatic cells.

Fibroblast growth factor receptor 4 single nucleotide polymorphism Gly388Arg in head and neck carcinomas

BACKGROUND

Head and neck squamous cell carcinoma (HNSCC) is considered to be a progressive disease resulting from alterations in multiple genes regulating cell proliferation and differentiation like receptor tyrosine kinases (RTKs) and members of the fibroblast growth factor receptors (FGFR)-family. Single-nucleotide polymorphism (SNP) Arg388 of the FGFR4 is associated with a reduced overall survival in patients with cancers of various types. We speculate that FGFR4 expression and SNP is associated with worse survival in patients with HSNCC.

AIM

To investigate the potential clinical significance of FGFR4 Arg388 in the context of tumors arising in HNSCC, a comprehensive analysis of FGFR4 receptor expression and genotype in tumor tissues and correlated results with patients’ clinical data in a large cohort of patients with HNSCC was conducted.

METHODS

Surgical specimens from 284 patients with HNSCC were retrieved from the Institute of Pathology at the Ludwig-Maximilian-University in Germany. Specimens were analyzed using immunohistochemistry and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The expression of FGFR4 was analyzed in 284 surgical specimens of HNSCC using immunohistochemstry. FGFR4 polymorphism was detected by PCR-RFLP. Patients’ clinical data with a minimum follow-up of 5 years were statistically evaluated with a special emphasis on survival analysis employing Kaplan-Meier estimator and Cox regression analysis.

RESULTS

Concerning the invasive tumor areas the intensity of the FGFR4 expression was evaluated in a four-grade system: no expression, low expression, intermediate and high expression. FGFR4 expression was scored as “high” (+++) in 74 (26%), “intermediate” (++) in 103 (36.3%), and “low” (+) in 107 (36.7%) cases. Analyzing the FGFR4 mutation it was found in 96 tumors (33.8%), 84 of them (29.6%) having a heterozygous and 12 (4.2%) homozygous mutated Arg388 allele. The overall frequency concerning the mutant alleles demonstrated 65% vs 34% mutated alleles in general. FGFR4 Arg388 was significantly associated with advanced tumor stage (P < 0.004), local metastasis (P < 0.0001) and reduced disease-free survival (P < 0.01). Furthermore, increased expression of FGFR4 correlated significantly with worse overall survival (P < 0.003).

CONCLUSION

In conclusion, the FGFR4 Arg388 genotype and protein expression of FGFR4 impacts tumor progression in patients with HNSCC and may present a useful target within a multimodal therapeutic intervention.

Membrane-associated epithelial cell adhesion molecule is slowly cleaved by γ-secretase prior to efficient proteasomal degradation of its intracellular domain

Regulated intramembrane proteolysis (RIP) is a key mechanism for activating transmembrane proteins such as epithelial cell adhesion molecule (EpCAM) for cellular signaling and degradation. EpCAM is highly expressed in carcinomas and progenitor and embryonic stem cells and is involved in the regulation of cell adhesion, proliferation, and differentiation. Strictly sequential cleavage of EpCAM through RIP involves initial shedding of the extracellular domain by α-secretase (ADAM) and β-secretase (BACE) sheddases, generating a membrane-tethered C-terminal fragment EpCTF. Subsequently, the rate-limiting γ-secretase complex catalyzes intramembrane cleavage of EpCTF, generating an extracellular EpCAM-Aβ-like fragment and an intracellular EpICD fragment involved in nuclear signaling. Here, we have combined biochemical approaches with live-cell imaging of fluorescent protein tags to investigate the kinetics of γ-secretase-mediated intramembrane cleavage of EpCTF. We demonstrate that γ-secretase-mediated proteolysis of exogenously and endogenously expressed EpCTF is a slow process with a 50% protein turnover in cells ranging from 45 min to 5.5 h. The slow cleavage was dictated by γ-secretase activity and not by EpCTF species, as indicated by cross-species swapping experiments. Furthermore, both human and murine EpICDs generated from EpCTF by γ-secretase were degraded efficiently (94-99%) by the proteasome. Hence, proteolytic cleavage of EpCTF is a comparably slow process, and EpICD generation does not appear to be suited for rapidly transducing extracellular cues into nuclear signaling, but appears to provide steady signals that can be further controlled through efficient proteasomal degradation. Our approach provides an unbiased bioassay to investigate proteolytic processing of EpCTF in single living cells.

EpCAM ectodomain EpEX is a ligand of EGFR that counteracts EGF-mediated epithelial-mesenchymal transition through modulation of phospho-ERK1/2 in head and neck cancers

Head and neck squamous cell carcinomas (HNSCCs) are characterized by outstanding molecular heterogeneity that results in severe therapy resistance and poor clinical outcome. Inter- and intratumoral heterogeneity in epithelial-mesenchymal transition (EMT) was recently revealed as a major parameter of poor clinical outcome. Here, we addressed the expression and function of the therapeutic target epidermal growth factor receptor (EGFR) and of the major determinant of epithelial differentiation epithelial cell adhesion molecule (EpCAM) in clinical samples and in vitro models of HNSCCs. We describe improved survival of EGFR^low/EpCAM^high HNSCC patients (n = 180) and provide a molecular basis for the observed disparities in clinical outcome. EGF/EGFR have concentration-dependent dual capacities as inducers of proliferation and EMT through differential activation of the central molecular switch phosphorylated extracellular signal–regulated kinase 1/2 (pERK1/2) and EMT transcription factors (EMT-TFs) Snail, zinc finger E-box-binding homeobox 1 (Zeb1), and Slug. Furthermore, soluble ectodomain of EpCAM (EpEX) was identified as a ligand of EGFR that activates pERK1/2 and phosphorylated AKT (pAKT) and induces EGFR-dependent proliferation but represses EGF-mediated EMT, Snail, Zeb1, and Slug activation and cell migration. EMT repression by EpEX is realized through competitive modulation of pERK1/2 activation strength and inhibition of EMT-TFs, which is reflected in levels of pERK1/2 and its target Slug in clinical samples. Accordingly, high expression of pERK1/2 and/or Slug predicted poor outcome of HNSCCs. Hence, EpEX is a ligand of EGFR that induces proliferation but counteracts EMT mediated by the EGF/EGFR/pERK1/2 axis. Therefore, the emerging EGFR/EpCAM molecular cross talk represents a promising target to improve patient-tailored adjuvant treatment of HNSCCs.

Head and neck squamous cell carcinomas (HNSCCs) display poor survival, with death rates above 55%. Major factors affecting survival are metastases’ formation and therapy resistance. Phenotypic changes during partial epithelial-mesenchymal transition (EMT) provide tumor cells with increased migration, invasion, and therapy resistance. Understanding molecular mechanisms of EMT, as a central process of the metastatic cascade and the development of therapy resistance, is therefore important. In the present work, we identified molecular cross talk between epidermal growth factor receptor (EGFR) and epithelial cell adhesion molecule (EpCAM) as a novel determinant of clinical outcome in HNSCCs. Low levels of EGFR but high levels of EpCAM (EGFR^low/EpCAM^high) were associated with favorable prognosis, with survival rates above 90%, whereas EGFR^high/EpCAM^low correlated with poor survival, below 10%. EGFR was shown to have a concentration-dependent capacity to induce proliferation and EMT. Proteolytic cleavage of the extracellular domain of EpCAM (EpEX) produces a ligand of EGFR that induces EGFR-dependent proliferation but counteracts EGF-induced EMT. We delineate an EGFR/extracellular signal–regulated kinase 1/2 (ERK1/2)/EpCAM signaling axis that may be a promising therapeutic target for HNSCCs.

Abstract 1059: EpCAM differentially expressed on circulating and disseminated tumor cells promotes tumor metastasis in breast cancer patients

To investigate the role of EpCAM expressed on both circulating tumor cells (CTCs) in peripheral blood and disseminated tumor cells (DTCs) in bone marrow with respect to tumor metastases, the integrated subtraction enrichment and immunostaining-FISH (SE-iFISH) was performed to quantify, phenotypically and karyotypically characterize cytogenetically abnormal CTCs and DTCs expressing EpCAM in breast cancer patients. In a cohort of 34 recruited late stage patients, consisting of 32 metastatic and 2 non-metastatic subjects, the average number of detected CTCs in metastatic vs non-metastatic patients was 25 and 18 cells, respectively. Among those CTCs in metastatic subjects, 23.4% of them showed EpCAM+, whereas none of EpCAM+ CTCs was detected in non-metastatic patients. There were total of 49 CTC clusters detected in metastatic patients, and 33% of those clusters were EpCAM+, however, only 3 CTC clusters were found in non-metastatic patients, and none of them was EpCAM+. In the case of DTCs, the average number of 2224 and 364 DTCs per subject was detected in metastatic vs non-metastatic subjects, with EpCAM+ ratio of 66.53% in metastatic and 8% in non-metastatic patients. Analysis of DTC clusters indicated that the average of 226 and 21 DTC clusters/subject were identified in metastatic and non-metastatic patients, respectively, and metastatic subjects showed 62% of DTC clusters EpCAM+, whereas 37% of clusters were EpCAM+ in non-metastatic patients. Comparing to the breast cancer serum biomarker CA15-3 detected in 32 metastatic cancer patients, showing positivity (≥28 ng/ml) of only 41% (13 out of 32), both CTCs (≥5) and DTCs (≥5) had a positivity rate of 81 (26 out of 32) and 97% (31 out of 32), respectively. Obtained results indicated that EpCAM+ CTCs and DTCs are reliable markers in terms of evaluating therapeutic efficacy and predicting cancer patients' prognosis.

Citation Format: Peter P. Lin, Junjian Li, Daisy Wang, Olivier Gires, Hongxia Wang. EpCAM differentially expressed on circulating and disseminated tumor cells promotes tumor metastasis in breast cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1059.

A high-content screen for small-molecule regulators of epithelial cell-adhesion molecule (EpCAM) cleavage yields a robust inhibitor

Epithelial cell-adhesion molecule (EpCAM) is a transmembrane protein that regulates cell cycle progression and differentiation and is overexpressed in many carcinomas. The EpCAM-induced mitogenic cascade is activated via regulated intramembrane proteolysis (RIP) of EpCAM by ADAM and γ-secretases, generating the signaling-active intracellular domain EpICD. Because of its expression pattern and molecular function, EpCAM is a valuable target in prognostic and therapeutic approaches for various carcinomas. So far, several immunotherapeutic strategies have targeted the extracellular domain of EpCAM. However, targeting the intracellular signaling cascade of EpCAM holds promise for specifically interfering with EpCAM's proliferation-stimulating signaling cascade. Here, using a yellow fluorescence protein-tagged version of the C-terminal fragment of EpCAM, we established a high-content screening (HCS) of a small-molecule compound library (n = 27,280) and characterized validated hits that target EpCAM signaling. In total, 128 potential inhibitors were initially identified, of which one compound with robust inhibitory effects on RIP of EpCAM was analyzed in greater detail. In summary, our study demonstrates that the development of an HCS for small-molecule inhibitors of the EpCAM signaling pathway is feasible. We propose that this approach may also be useful for identifying chemical compounds targeting other disorders involving membrane cleavage-dependent signaling pathways.

Circulating and disseminated tumor cells: diagnostic tools and therapeutic targets in motion

Enumeration of circulating tumor cells (CTCs) in peripheral blood with the gold standard CellSearchTM has proven prognostic value for tumor recurrence and progression of metastatic disease. Therefore, the further molecular characterization of isolated CTCs might have clinical relevance as liquid biopsy for therapeutic decision-making and to monitor disease progression. The direct analysis of systemic cancer appears particularly important in view of the known disparity in expression of therapeutic targets as well as epithelial-to-mesenchymal transition (EMT)-based heterogeneity between primary and systemic tumor cells, which all substantially complicate monitoring and therapeutic targeting at present. Since CTCs are the potential precursor cells of metastasis, their in-depth molecular profiling should also provide a useful resource for target discovery. The present review will discuss the use of systemically spread cancer cells as liquid biopsy and focus on potential target antigens.

Confocal laser endomicroscopy in head and neck malignancies using FITC-labelled EpCAM- and EGF-R-antibodies in cell lines and tumor biopsies

Intraoperative detection of residual malignant cells at tumor margins following excision of primary tumors could help improving surgery and thus patients' outcome. The feasibility of the tumor antigens epidermal growth factor receptor (EGF-R) and epithelial cell adhesion molecule (EpCAM) for antibody-dependent confocal laser scanning endomicroscopy (CLE)-mediated visualization of malignant cells was addressed. Both tumor antigens are highly and frequently expressed in the majority of carcinomas, including head and neck squamous cell carcinomas (HNSCC), and represent prognostic and therapeutic tumor target molecules. FITC-conjugated EGF-R- and EpCAM-specific antibodies served as molecular tools for the detection of antigen-positive cells using the CLE technology. Specificity of both antibodies and their ability to discriminate tumor from non-tumor cells were assessed in vitro with human fibroblasts and PCI-1 HNSCC cell lines, and ex vivo on primary HNSCC samples (n = 11) and healthy mucosa (n = 5). Antigen specificity of the used EpCAM-specific antibody was superior to that of the EGF-R-specific antibody both in vitro and ex vivo (100% vs. 31.25%), and allowed visualization of cellular structures in CLE measurements. These results hold promise for possible future applications in humans.

Characterization of Rare, Dormant, and Therapy-Resistant Cells in Acute Lymphoblastic Leukemia

Tumor relapse is associated with dismal prognosis, but responsible biological principles remain incompletely understood. To isolate and characterize relapse-inducing cells, we used genetic engineering and proliferation-sensitive dyes in patient-derived xenografts of acute lymphoblastic leukemia (ALL). We identified a rare subpopulation that resembled relapse-inducing cells with combined properties of long-term dormancy, treatment resistance, and stemness. Single-cell and bulk expression profiling revealed their similarity to primary ALL cells isolated from pediatric and adult patients at minimal residual disease (MRD). Therapeutically adverse characteristics were reversible, as resistant, dormant cells became sensitive to treatment and started proliferating when dissociated from the in vivo environment. Our data suggest that ALL patients might profit from therapeutic strategies that release MRD cells from the niche.

Cleavage and cell adhesion properties of human epithelial cell adhesion molecule (HEPCAM)

Human epithelial cell adhesion molecule (HEPCAM) is a tumor-associated antigen frequently expressed in carcinomas, which promotes proliferation after regulated intramembrane proteolysis. Here, we describe extracellular shedding of HEPCAM at two α-sites through a disintegrin and metalloprotease (ADAM) and at one β-site through BACE1. Transmembrane cleavage by γ-secretase occurs at three γ-sites to generate extracellular Aβ-like fragments and at two ϵ-sites to release human EPCAM intracellular domain HEPICD, which is efficiently degraded by the proteasome. Mapping of cleavage sites onto three-dimensional structures of HEPEX cis-dimer predicted conditional availability of α- and β-sites. Endocytosis of HEPCAM warrants acidification in cytoplasmic vesicles to dissociate protein cis-dimers required for cleavage by BACE1 at low pH values. Intramembrane cleavage sites are accessible and not part of the structurally important transmembrane helix dimer crossing region. Surprisingly, neither chemical inhibition of cleavage nor cellular knock-out of HEPCAM using CRISPR-Cas9 technology impacted the adhesion of carcinoma cell lines. Hence, a direct function of HEPCAM as an adhesion molecule in carcinoma cells is not supported and appears to be questionable.

TKTL1 expression in human malign and benign cell lines

Background

Overexpression of transketolase-like 1 protein TKTL1 in cancer cells has been reported to correlate with enhanced glycolysis and lactic acid production. Furthermore, enhanced TKTL1 expression was put into context with resistance to chemotherapy and ionizing radiation. Here, a panel of human malign and benign cells, which cover a broad range of chemotherapy and radiation resistance as well as reliance on glucose metabolism, was analyzed in vitro for TKTL1 expression.

Methods

17 malign and three benign cell lines were characterized according to their expression of TKTL1 on the protein level with three commercially available anti-TKTL1 antibodies utilizing immunohistochemistry and Western blot, as well as on mRNA level with three published primer pairs for RT-qPCR. Furthermore, sensitivities to paclitaxel, cisplatin and ionizing radiation were assessed in cell survival assays. Glucose consumption and lactate production were quantified as surrogates for the “Warburg effect”.

Results

Considerable amounts of tktl1 mRNA and TKTL1 protein were detected only upon stable transfection of the human embryonic kidney cell line HEK293 with an expression plasmid for human TKTL1. Beyond that, weak expression of endogenous tktl1 mRNA was measured in the cell lines JAR and U251. Western blot analysis of JAR and U251 cells did not detect TKTL1 at the expected size of 65 kDa with all three antibodies specific for TKTL1 protein and immunohistochemical staining was observed with antibody JFC12T10 only. All other cell lines tested here revealed expression of tktl1 mRNA below detection limits and were negative for TKTL1 protein. However, in all cell lines including TKTL1-negative HEK293-control cells, antibody JFC12T10 detected multiple proteins with different molecular weights. Importantly, JAR and U251 did neither demonstrate an outstanding production of lactic acid nor increased resistance against chemotherapeutics or to ionizing radiation, respectively.

Conclusion

Using RT-qPCR and three different antibodies we observed only exceptional occurrence of TKTL1 in a panel of malignant human cell lines in vitro. The presence of TKTL1 was unrelated to either the rate of glucose consumption/lactic acid production or resistance against chemo- and radiotherapy.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2407-15-2) contains supplementary material, which is available to authorized users.

Reducing tumor growth and angiogenesis using a triple therapy measured with Contrast-enhanced ultrasound (CEUS)

Background

To evaluate the in vivo response by detecting the anti-angiogenic and invasion-inhibiting effects of a triple-combination-therapy in an experimental-small-animal-squamous-cell-carcinoma-model using the “flash-replenishment” (FR) method to assess tissue hemodynamics via contrast-enhanced-ultrasound (CEUS).

Methods

Human hypopharynx-carcinoma-cells were subcutaneously injected into the left flank of 22-female-athymic-nude-rats. After seven days of subcutaneous tumor growth, FR-measurements were performed on each rat. Treatment-group and control-group were treated every day for a period of one week, with the treatment-group receiving solvents containing a triple therapy of Upamostat®, Celecoxib® and Ilomastat® and the control-group solvents only. On day seven, follow-up measurements were performed using the same measurement protocol to assess the effects of the triple therapy. VueBox® was used to quantify the kinetic parameters and additional immunohistochemistry analyses were performed for comparison with and validation of the CEUS results against established methods (Proliferation/Ki-67, vascularization/CD31, apoptosis/caspase3).

Results

Compared to the control-group, the treatment-group that received the triple-therapy resulted in a reduction of tumor growth by 48.6% in size. Likewise, the immunohistochemistry results showed significant decreases in tumor proliferation and vascularization in the treatment-group in comparison to the control-group of 26%(p≤0.05) and 32.2%(p≤0.05) respectively. Correspondingly, between the baseline and follow-up measurements, the therapy-group was associated with a significant(p ≤ 0.01) decrease in the relative-Blood-Volume(rBV) in both the whole tumor(wt) and hypervascular tumor(ht) areas (p≤0.01), while the control-group was associated with a significant (p≤0.01) increase of the rBV in the wt area and a non-significant increase (p≤0.16) in the ht area. The mean-transit-time (mTT) of the wt and the ht areas showed a significant increase (p≤0.01) in the follow-up measurements in the therapy group.

Conclusion

The triple-therapy is feasible and effective in reducing both tumor growth and vascularization. In particular, compared with the placebo-group, the triple-therapy-group resulted in a reduction in tumor growth of 48.6% in size when assessed by CEUS and a significant reduction in the number of vessels in the tumor of 32% as assessed by immunohistochemistry. As the immunohistochemistry supports the CEUS findings, CEUS using the “flash replenishment”(FR) method appears to provide a useful assessment of the anti-angiogenic and invasion-inhibiting effects of a triple combination therapy.

EpCAM and the biology of hepatic stem/progenitor cells

Epithelial cell adhesion molecule (EpCAM) is a transmembrane glycoprotein, which is frequently and highly expressed on carcinomas, tumor-initiating cells, selected tissue progenitors, and embryonic and adult stem cells. During liver development, EpCAM demonstrates a dynamic expression, since it can be detected in fetal liver, including cells of the parenchyma, whereas mature hepatocytes are devoid of EpCAM. Liver regeneration is associated with a population of EpCAM-positive cells within ductular reactions, which gradually lose the expression of EpCAM along with maturation into hepatocytes. EpCAM can be switched on and off through a wide panel of strategies to fine-tune EpCAM-dependent functional and differentiative traits. EpCAM-associated functions relate to cell-cell adhesion, proliferation, maintenance of a pluripotent state, regulation of differentiation, migration, and invasion. These functions can be conferred by the full-length protein and/or EpCAM-derived fragments, which are generated upon regulated intramembrane proteolysis. Control by EpCAM therefore not only depends on the presence of full-length EpCAM at cellular membranes but also on varying rates of the formation of EpCAM-derived fragments that have their own regulatory properties and on changes in the association of EpCAM with interaction partners. Thus spatiotemporal localization of EpCAM in immature liver progenitors, transit-amplifying cells, and mature liver cells will decisively impact the regulation of EpCAM functions and might be one of the triggers that contributes to the adaptive processes in stem/progenitor cell lineages. This review will summarize EpCAM-related molecular events and how they relate to hepatobiliary differentiation and regeneration.

Dynamic EpCAM expression on circulating and disseminating tumor cells: causes and consequences

Formation of metastasis is the most important and lethal step in cancer progression. Circulating and disseminated cancer cells (CTCs/DTCs) in blood and bone marrow are considered as potential metastases-inducing cells. Their detection and characterization has, therefore, become a field of major interest in translational and clinical research in oncology. The main strategy to detect these cells relies thus far on the epithelial characteristics of carcinoma cells and epithelial cell adhesion molecule (EpCAM) represents the most commonly used epithelial marker to capture CTCs/DTCs. Recent data, however, demonstrated a dynamic expression of EpCAM associated with a loss during epithelial-to-mesenchymal transition. The present review summarizes the potential mechanisms and reasons for a dynamic expression of EpCAM.

Regulated intramembrane proteolysis and degradation of murine epithelial cell adhesion molecule mEpCAM

Epithelial cell adhesion molecule EpCAM is a transmembrane glycoprotein, which is highly and frequently expressed in carcinomas and (cancer-)stem cells, and which plays an important role in the regulation of stem cell pluripotency. We show here that murine EpCAM (mEpCAM) is subject to regulated intramembrane proteolysis in various cells including embryonic stem cells and teratocarcinomas. As shown with ectopically expressed EpCAM variants, cleavages occur at α-, β-, γ-, and ε-sites to generate soluble ectodomains, soluble Aβ-like-, and intracellular fragments termed mEpEX, mEp-β, and mEpICD, respectively. Proteolytic sites in the extracellular part of mEpCAM were mapped using mass spectrometry and represent cleavages at the α- and β-sites by metalloproteases and the b-secretase BACE1, respectively. Resulting C-terminal fragments (CTF) are further processed to soluble Aβ-like fragments mEp-β and cytoplasmic mEpICD variants by the g-secretase complex. Noteworthy, cytoplasmic mEpICD fragments were subject to efficient degradation in a proteasome-dependent manner. In addition the γ-secretase complex dependent cleavage of EpCAM CTF liberates different EpICDs with different stabilities towards proteasomal degradation. Generation of CTF and EpICD fragments and the degradation of hEpICD via the proteasome were similarly demonstrated for the human EpCAM ortholog. Additional EpCAM orthologs have been unequivocally identified in silico in 52 species. Sequence comparisons across species disclosed highest homology of BACE1 cleavage sites and in presenilin-dependent γ-cleavage sites, whereas strongest heterogeneity was observed in metalloprotease cleavage sites. In summary, EpCAM is a highly conserved protein present in fishes, amphibians, reptiles, birds, marsupials, and placental mammals, and is subject to shedding, γ-secretase-dependent regulated intramembrane proteolysis, and proteasome-mediated degradation.

High EpCAM expression is linked to proliferation and lauren classification in gastric cancer

BACKGROUND

The association of EpCAM expression with the progression of gastric cancer remains unclear. Here, we investigated the expression of EpCAM in gastric cancer subtypes and correlated the data to tumor cell proliferation and clinicopathologic factors.

METHODS

The intratumoral expression of EpCAM was assessed in 163 primary gastric cancers (61 diffuse-, 62 intestinal-, 32 mixed-type and 8 unclassified tumors) by immunohistochemistry, using the monoclonal antibody Ber-EP4. Intensity of staining was classified according the HercepTest-score using a standardized scoring system. Ki-67 was used to examine the proliferation in tumor tissue.

RESULTS

Strong EpCAM expression was observed in 77% of the tumors and in 85% of the corresponding lymph nodes. Of the primary tumors, 58% (n=74) presented a homogeneous intratumoral EpCAM expression while 42% were characterised by a heterogenous expression pattern. Tumors with high EpCAM expression at the invasive front were associated with significantly (p=0.03) higher proportion of lymph node metastases and lower median overall survival (p=0.001). Diffuse type tumors presented a significantly higher EpCAM expression at the invasion front compared with the tumor centre (p=0.036). Multivariate survival analysis identified high EpCAM expression at the invasive front as an independent prognostic factor.We observed a significant (p=0.001) correlation between high EpCAM expression and higher tumor cell proliferation.

CONCLUSION

High EpCAM expression associates with proliferation and progression of gastric cancer, especially in the diffuse type. Considering the discontenting results of the current adjuvant concepts for gastric cancer patients, EpCAM might be target in the adjuvant therapy of this malignant disease.

CD133 is a predictor of poor survival in head and neck squamous cell carcinomas

BACKGROUND

The pentaspan protein CD133 (Prominin-1) is a predictive marker and part of the signature of tumour-initiating cells (TICs) for various cancer entities.

METHODS

The correlation of CD133 expression with clinical parameters was assessed in primary samples of head and neck squamous cell carcinomas (n=98) and normal mucosas (n=24).

RESULTS

A gradual and inversely proportional correlation between CD133 expression in primary tumours and decreased overall survival was observed, along with a positive correlation with the presence of lymph node metastases.

CONCLUSIONS

CD133 has the potential of being a novel clinically relevant prognostic marker for head and neck malignancies, which is possibly involved in regulation of tumourigenicity.

Rapid and non-enzymatic in vitro retrieval of tumour cells from surgical specimens

The study of tumourigenesis commonly involves the use of established cell lines or single cell suspensions of primary tumours. Standard methods for the generation of short-term tumour cell cultures include the disintegration of tissue based on enzymatic and mechanical stress. Here, we describe a simple and rapid method for the preparation of single cells from primary carcinomas, which is independent of enzymatic treatment and feeder cells. Tumour biopsies are processed to 1 mm(3) cubes termed explants, which are cultured 1-3 days on agarose-coated well plates in specified medium. Through incisions generated in the explants, single cells are retrieved and collected from the culture supernatant and can be used for further analysis including in vitro and in vivo studies. Collected cells retain tumour-forming capacity in xenotransplantation assays, mimic the phenotype of the primary tumour, and facilitate the generation of cell lines.

MMP7 is a target of the tumour-associated antigen EpCAM

Epithelial cell adhesion molecule (EpCAM) is a single-transmembrane protein, which is involved in numerous cellular processes including cell adhesion, proliferation, maintenance of stemness of embryonic cells and progenitors, migration and invasion. Activation of signal transduction by EpCAM is warranted by regulated intramembrane proteolysis and nuclear translocation of the intracellular domain EpICD. Here, we describe matrix metalloproteinase 7 (MMP7) as a target gene of EpCAM signalling viaEpICD nuclear translocation. EpCAM and MMP7 expression pattern and levels positively correlated in vitro and in vivo, and were strongly elevated in primary carcinomas of the head and neck area. Hence, MMP7 is a novel target of EpCAM signalling.

Lessons from common markers of tumor-initiating cells in solid cancers

Tumor-initiating cells (TICs) have emerged as the driving force of carcinomas, which appear as hierarchically structured. TICs as opposed to the tumor bulk display tumor forming potential, which is linked to a certain degree of self-renewal and differentiation, both major features of stem cells. Markers such as CD44, CD133, CD24, EpCAM, CD166, Lgr5, CD47, and ALDH have been described, which allow for the prospective enrichment of TICs. It is conspicuous that the same markers allow for an enrichment of TICs in various entities and, on the other hand, that different combinations of these markers were independently reported for the same tumor entity. Potential functions of these markers in the regulation of TIC phenotypes remained somewhat neglected although they might give insights in common molecular themes of TICs. The present review discusses major TIC markers with respect to their function and potential contributions to the tumorigenic phenotype of TICs.