[Show abstract][Hide abstract] ABSTRACT: Distant metastases arise in 20-30% of patients with squamous cell carcinoma of the head and neck (HNSCC) in the 2 years following treatment. Therapeutic options are limited and the outcome of the patients is poor. The identification of predictive biomarkers of patient at risk for distant metastasis and therapies are urgently needed. We previously identified a clinical subgroup, called "R1" characterized by high propensity for rapid distant metastasis. Here, we showed that "R1" patients do not or at very low level express caveolin-1 (Cav1). Low or no expression of Cav1 is of bad prognosis. Disappearance of Cav1 enables cells to undergo epithelial-mesenchymal transition (EMT). EMT is associated with enhanced migration and invasion. Our study uncovered a new target, α5β1 integrin. Targeting α5β1 integrins might not only prevent metastasis of HNSCC but also delay the development of the primary tumor by reducing tumor cell viability. Cav1 detection might be taken into consideration in the future in the clinic not only to identify patients at high risk of metastasis but also to select patient who might benefit from an anti-integrin therapy.
[Show abstract][Hide abstract] ABSTRACT: Estrogen receptor alpha36 (ERalpha36), a variant of estrogen receptor alpha (ER) is expressed in about half of breast tumors, independently of the [ER+]/[ER-] status. In vitro, ERalpha36 triggers mitogenic non-genomic signaling and migration ability in response to 17beta-estradiol and tamoxifen. In vivo, highly ERalpha36 expressing tumors are of poor outcome especially as [ER+] tumors are submitted to tamoxifen treatment which, in turn, enhances ERalpha36 expression.
Our study aimed to validate ERalpha36 expression as a reliable prognostic factor for cancer progression from an estrogen dependent proliferative tumor toward an estrogen dispensable metastatic disease. In a retrospective study, we tried to decipher underlying mechanisms of cancer progression by using an original modeling of the relationships between ERalpha36, other estrogen and growth factor receptors and metastatic marker expression. Nonlinear correlation analyses and mutual information computations led to characterize a complex network connecting ERalpha36 to either non-genomic estrogen signaling or to metastatic process.
This study identifies ERalpha36 expression level as a relevant classifier which should be taken into account for breast tumors clinical characterization and [ER+] tumor treatment orientation, using a generic approach for the rapid, cheap and relevant evaluation of any candidate gene expression as a predictor of a complex biological process.
Preview · Article · Jun 2015 · BMC Systems Biology
[Show abstract][Hide abstract] ABSTRACT: The molecular response to hypoxia is a critical cellular process implicated in cancer, and a target for drug development. The activity of the major player, HIF1α, is regulated at different levels by various factors, including the transcription factor ELK3. The molecular mechanisms of this intimate connection remain largely unknown. Whilst investigating global ELK3-chromatin interactions, we uncovered an unexpected connection that involves the microRNA hsa-miR-155-5p, a hypoxia-inducible oncomir that targets HIF1α. One of the ELK3 chromatin binding sites, detected by Chromatin Immuno-Precipitation Sequencing (ChIP-seq) of normal Human Umbilical Vein Endothelial Cells (HUVEC), is located at the transcription start site of the MIR155HG genes that expresses hsa-miR-155-5p. We confirmed that ELK3 binds to this promoter by ChIP and quantitative polymerase chain reaction (QPCR). We showed that ELK3 and hsa-miR-155-5p form a double-negative regulatory loop, in that ELK3 depletion induced hsa-miR-155-5p expression and hsa-miR-155-5p expression decreased ELK3 expression at the RNA level through a conserved target sequence in its 3'-UTR. We further showed that the activities of hsa-miR-155-5p and ELK3 are functionally linked. Pathway analysis indicates that both factors are implicated in related processes, including cancer and angiogenesis. Hsa-miR-155-5p expression and ELK3 depletion have similar effects on expression of known ELK3 target genes, and on in-vitro angiogenesis and wound closure. Bioinformatic analysis of cancer RNA-seq data shows that hsa-miR-155-5p and ELK3 expression are significantly anti-correlated, as would be expected from hsa-miR-155-5p targeting ELK3 RNA. Finally, hypoxia (0% oxygen) down-regulates ELK3 mRNA in a microRNA and hsa-miR-155-5p dependent manner. These results tie ELK3 into the hypoxia response pathway through an oncogenic microRNA and into a circuit implicated in the dynamics of the hypoxic response. This crosstalk could be important for the development of new treatments for a range of pathologies.
[Show abstract][Hide abstract] ABSTRACT: Breast cancer is the main cause of cancer-induced morbidity and mortality in women. Breast tumors are usually classified according to their ERa66 status. Such a classification led to the use of endocrine therapeutic agents against ER-positive tumors [ER+]. Nevertheless, numerous therapeutic failures are observed due to unclear resistance mechanism. ERa66 was considered as the unique functional estrogen receptor in hormone sensitive breast tumor until the recent identification of membrane bound new estrogen receptors: the G protein coupled estrogen receptor (GPER) and the 36kDa ERa splice variant (ERa36). Surprisingly, ERa36 stimulates cell proliferation in response to tamoxifen treatment and could therefore be involved in the acquired resistance to this compound. Moreover, a high ERa36 expression level correlates with a short term survival for ERa66-negative patients as well as enhanced tumorigenesis and metastatic potential of triple-negative cells in vitro. The aim of our project was to improve the classification of so-called "ER-positive" breast tumors by taking into account the key role of ERa36 and GPER in the control of non genomic estrogen response and metastatic potential. We set up a retrospective study, performed on hundreds of breast tumor samples, in order to better define the field of acceptance of [ER+] versus [ER-] classification and to help the clinicians choosing the best therapeutic compounds. We addressed two main questions: 1- Are ERa36 and GPER predictive markers of therapeutic response in ER-positive tamoxifen-treated patients [ER+,TAM+]? 2- Is a high ERa36 or/and GPER expression level of poor prognosis because these receptors stimulate tumor progression and metastatic potential? ERa36, GPER and metastatic marker expressions were measured by real-time PCR in almost 100 [ER+,TAM] as well as 60 triple-negatives [ER-,TAM-] tumor samples. Then, we performed statistical analyses between gene expression levels and clinical parameters (grade, survival, treatment). Modeling of the potential relationship between the genes tested using nonlinear correlation analyses, Bayesian inference and transfer entropy computation led to the characterization of complex network connecting non genomic estrogen signaling and metastatic process. Hence, ERa36 expression is strongly related to GPER, Snail1, Vim and MMP9A in [ER+, TAM+] samples. This suggests that, after tamoxifen treatment, ERa36 may stimulate the metastatic potential of [ER+] tumor in vivo. Such a model will be first tested in vitro in hormone-dependent or triple negative cell lines. Taken together, the results from this project should lead to (i) a better understanding of the breast tumor hormone sensitive status, (ii) a validation of new predictive markers of response in order to improve therapeutic orientation, (iii) the potential discovery of new therapeutic targets in triple-negative tumors.
[Show abstract][Hide abstract] ABSTRACT: The DNA repair protein DDB2 has been implicated in promoting cell cycle progression by regulating gene expression. DDB2 is selectively overexpressed in breast tumor cells that are non-invasive, but not in those that are invasive. We found that its overexpression in invasive human breast tumor cells limited their motility and invasiveness in vitro and blocked their ability to colonize lungs in vivo, defining a new function for DDB2 in malignant progression. DDB2 overexpression attenuated the activity of NF-kB and the expression of its target matrix metalloprotease MMP9. Mechanistic investigations indicated that DDB2 decreased NF-kB activity by upregulating expression of IkBa by binding the proximal promoter of this gene. This effect was causally linked to invasive capacity. Indeed, knockdown of DDB2-induced IkBa gene expression restored NF-kB activity and MMP9 expression, along with the invasive properties of breast tumor cells overexpressing DDB2. Taken together, our findings enlighten understanding of how breast cancer cells progress to an invasive phenotype and underscore potential clinical interest in DDB2 as a prognostic marker or therapeutic target in this setting.
[Show abstract][Hide abstract] ABSTRACT: Purpose:
Distant metastasis after treatment is observed in about 20% of squamous cell carcinoma of the head and neck (HNSCC). In the absence of any validated robust biomarker, patients at higher risk for metastasis cannot be provided with tailored therapy. To identify prognostic HNSCC molecular subgroups and potential biomarkers, we have conducted genome-wide integrated analysis of four omic sets of data.
Using state-of-the-art technologies, a core set of 45 metastasizing and 55 nonmetastasizing human papillomavirus (HPV)-unrelated HNSCC patient samples were analyzed at four different levels: gene expression (transcriptome), DNA methylation (methylome), DNA copy number (genome), and microRNA (miRNA) expression (miRNome). Molecular subgroups were identified by a model-based clustering analysis. Their clinical relevance was evaluated by survival analysis, and functional significance by pathway enrichment analysis.
Patient subgroups selected by transcriptome, methylome, or miRNome integrated analysis are associated with shorter metastasis-free survival (MFS). A common subgroup, R1, selected by all three omic approaches, is statistically more significantly associated with MFS than any of the single omic-selected subgroups. R1 and non-R1 samples display similar DNA copy number landscapes, but more frequent chromosomal aberrations are observed in the R1 cluster (especially loss at 13q14.2-3). R1 tumors are characterized by alterations of pathways involved in cell-cell adhesion, extracellular matrix (ECM), epithelial-to-mesenchymal transition (EMT), immune response, and apoptosis.
Integration of data across several omic profiles leads to better selection of patients at higher risk, identification of relevant molecular pathways of metastasis, and potential to discover biomarkers and drug targets.
Full-text · Article · Jun 2013 · Clinical Cancer Research
[Show abstract][Hide abstract] ABSTRACT: Patients with human papillomavirus (HPV)-related oropharyngeal tumors display improved prognosis. The biological basis of this tumor phenotype is poorly understood. We investigated whether increased lymphocyte infiltrate in HPV-positive oropharyngeal squamous cell carcinomas could account for better prognosis. We previously identified, in an Affymetrix GeneChip analysis of 83 HPV-unrelated and 11 HPV-related squamous cell carcinoma of the oropharynx, several candidate genes, including CD8α and CD3ζ. Their expression was validated in this study by qRT-PCR on an independent clinical series of 144 oropharyngeal tumors. Immunohistochemical staining of tumor specimens was performed to evaluate infiltration of tumor stroma by CD8+ and CD4+ lymphocytes. The prognostic value of CD8α and CD3ζ expression levels was measured by Kaplan-Meier and Cox regression model analyses. Immune response-related signaling pathways were found to be deregulated in HPV-positive oropharyngeal tumors. Expression of CD8α, CD3ζ, granzyme K, CD28 and integrin αL RNAs was upregulated in HPV-positive lesions when compared with HPV-unrelated tumors (p < 0.05). Stroma of HPV-positive tumors was frequently and strongly infiltrated by CD8α- and CD3ζ-positive T cells. CD8α RNA expression correlated with both improved global (Kaplan-Meier; p = 0.005; Cox regression: p = 0.003) and disease-free (Cox regression: p = 0.04) survival. CD3ζ RNA expression correlated with improved overall survival (Cox regression: p = 0.024). These results suggest that an increased cytotoxic T-cell-based antitumor immune response is involved in improved prognosis of patients with HPV-positive tumors.
Full-text · Article · Jan 2013 · International Journal of Cancer
[Show abstract][Hide abstract] ABSTRACT: Human papillomavirus (HPV)-related oropharyngeal cancer represents a distinct head and neck squamous cell carcinoma (HNSCC) subpopulation, with improved disease-free and overall survival. In general, HPV-positive HNSCCs express wild-type TP53, which could explain its increased radiosensitivity. However, the molecular mechanisms underlying this higher sensitivity remain elusive. We have previously shown that HPV-related oropharyngeal carcinomas express decreased levels of the NEDD8-activating enzyme 1/amyloid β precursor protein-binding protein 1 (NAE1/APP-BP1) gene. NAE1/APP-BP1 function is required for the NEDDylation of target proteins, and has been shown to be a negative regulator of p53 transcriptional activity. In this study, we addressed the hypothesis that NAE1/APP-BP1 expression levels regulate p53 activity and cell survival upon ionizing irradiation. We used the radiosensitive and naturally HPV16-infected UPCI:SCC90 cell line and the radioresistant and HPV-negative SQ20B cell line as the control. NAE1/APP-BP1 expression levels were modulated with expression constructs and siRNAs. Radiosensitivity was evaluated with clonogenic survival assays. p53 transcriptional activity was measured with a luciferase assay. The overexpression of NAE1/APP-BP1 in UPCI:SCC90 cells resulted in the increased NEDDylation of p53, inhibition of p53 activity and increased cell resistance to ionizing radiation. Conversely, the inhibition of NAE1/APP-BP1 expression in SQ20B cells induced p53-dependent cell death after treatment with X-rays. Taken together, these results indicate that NAE1/APP-BP1 and NEDDylation are invovled in modulating p53 activity and regulating its role in the response of cells to ionizing radiation. Our findings bring new insights in the molecular mechanisms underlying the increased radiosensitivity of HPV-related oropharyngeal tumors. This is of importance, as no reliable and robust predictive biomarkers for tumor response to radiotherapy are currently available. These results also have potential clinical significance, as drugs targeting NAE1/APP-BP1 have recently emerged as a novel therapeutic modality in cancer treatment.
Preview · Article · Aug 2012 · International Journal of Oncology
[Show abstract][Hide abstract] ABSTRACT: The infection of the head and neck epithelium by high-risk human papillomaviruses (HPV) is a risk factor for cancer onset and development. The incidence of HPV-related head and neck squamous cell carcinoma is currently increasing. These lesions display distinct clinical features. HPV positive patients are often younger and have a smaller history of tobacco smoking and alcohol drinking, but have a history of virus-transmitting sex practices. HPV-related tumours are mainly found in the oropharynx, are more associated to a local lymph node invasion and display a poorly differentiated morphology. Despite these more aggressive features, HPV-positive head and neck squamous cell carcinomas correlate with an improved local control, disease-free and global survival. It is thought that HPV-driven specific biologic abnormalities underlie higher tumour sensitivity to chemotherapeutic drugs and ionizing radiations. The expression of the HPV E6 and E7 oncoproteins induce cell transformation by interfering with cell signalling pathways involved in apoptosis, cell cycle, angiogenesis and induce the overexpression of the CDKN2A gene. Therefore, alternative treatments based on therapies targeting these pathways in combination with radiation dose de-escalation could be proposed to HPV-positive patients, if they are properly and reliably identified.
No preview · Article · Feb 2012 · Cancer/Radiothérapie