Detection and Outcome Markers . Metastasis . EMT . Aberrant Glycosylation, Drugs and Treatment . Therapeutic Targets

Ovarian Cancer Research

Ovarian cancer (OC) is the most lethal gynecological malignancy and the 5th leading cause of cancer death in women. OC is typically diagnosed at late stage, when the cancer has spread into the peritoneal cavity and complete surgical removal is difficult. The 5-year overall survival for patients diagnosed at this stage is 30%, in contrast to 90% 5-year survival for patients diagnosed at early stage. The disease recurrence is usually high due to insufficient therapies and risk to metastasis is considerable. Cancer screening and early detection have the potential to greatly decrease the mortality and morbidity from cancer, but currently available early detection markers like CA-125 or HE4 do not seem reliable enough.

The etiology of OC is until today not fully understood despite several decades of intensive research. Recent data suggest that OC arises from transformed epithelial cells in the fallopian tube rather than from the ovarian surface epithelium. At risk are women with germ line mutations in BRCA genes and somatic mutations in BRCA andTP53. Clinical management of patients with OC is by cytoreductive surgery and chemotherapy and rarely radiotherapy; immune therapeutic approaches are currently under clinical evaluation.

Metastasis is apart from therapy resistance a major obstacle and causative for OC-related death in OC treatment. OC preferably metastasizes (disseminates) into the peritoneal cavity and in particular to the omentum. The omentum is a layer of fatty tissue that covers and supports the intestines and organs in the lower abdominal area and that is lined by a monolayer of mesothelial cells. This may occur through different routes (lymphatic spread, hematogenous spread, and passive dissemination via ascites flow) and involves the shedding of tumor cells or clusters from the primary tumor and the colonization and establishment of secondary tumor (metastasis) at distant sites (e.g. omentum) via orchestrated processes including epithelial-to-mesenchymal transition.

The Ovarian Cancer Research (OCR) Group led by Prof. Viola Heinzelmann-Schwarz and her deputy Dr. Francis Jacob combines basic, translational, and clinical approaches to:

  • identify biomarkers and molecular signatures for early detection and prognostic outcome of OC (survival, therapy response, or relapse)
  • dissect the mechanisms of OC metastasis and identify potential routes of therapeutic Intervention
  • search for alternative and novel (precision medicine-driven) diagnostic and therapeutic approaches to the best benefit for OC patients
  • investigate biological roles of (aberrant) protein and lipid glycosylation in OC metastasis and resistance

 

Selected research projects

Basic and translational

Ovarian cancer – molecular signatures, prognosis, and treatment

We are specifically interested in subgroups of OC patients who live longer (long-term survivors, LTS) or respond much better to a given therapeutic regimen than others. We hypothesize that for instance LTS OC patients share distinct genetic and molecular signatures and have recently shown that in contrast to MELK (Kohler et al., 2016) expression of LATS does not associate with better prognosis (Montavon et al., 2019). We provide further evidence that serous ovarian and serous peritoneal cancer, although they are currently treated as one disease, are indeed distinct diseases with unique molecular signatures, suggesting that these diseases should be treated differently (Jacob et al., under review).

 

OC metastasis in the omentum

The omentum is the preferred site of OC dissemination, but it is unknown how this occurs and what the biological prerequisites are. In an interdisciplinary project (“Sinergia”) we aim reconstructing an ex vivo functional 3D omentum-model in order to investigate: (i) the mechanisms by which cancer cells colonize the omentum and form tumors, (ii) the key genes that transform “normal” fallopian tube cells into cancer cells, (iii) the key proteins and the key glycosylation signatures that govern these processes, and (iv) how these processes can be (therapeutically) inhibited. The experimental approaches include the disintegration of omental tissue derived from OC patients into its components (cancer cells, immune cells, adipocytes, and fibroblasts) using proteomics and single cell technologies. This knowledge is the basis for reconstruction of an ex vivo model by tissue engineering and 3D-bioprinting to study the network of various cell types in the presence of cancer cells. CRISPR/Cas9-mediated gene engineering is employed to investigate the key processes of metastasis.

 In particular, we currently investigate the role of integrin-alpha2 and specific ECM (extracellular matrix) proteins and their functional significance underlying molecular mechanisms in the colonization of the omentum with tumor cells. Preliminary data suggest that loss of integrin-alpha2 confers OC cells a mesenchymal phenotype, abrogates the interaction of tumor cells with collagen, and inhibits the mesothelial clearance, an experimental setup mimicking the colonization of the omentum with tumor cells.

 

Glycosylation of lipids and cell surface membrane proteins in cancer

The function and biological significance of cancer-associated (aberrant) glycosylation of key proteins (e.g. E-cadherin and integrins) and of glycosphingolipids (GSL) in OC metastasis are poorly understood. We have previously shown that globoside GSL are essential for an epithelial state and that the loss of them can shift in particular intermediate/hybrid ovarian cancer cells towards a mesenchymal state and phenotype (Jacob et al., 2018). We currently investigate the role of ganglioside GSL in MET. The data indicate that loss of gangliosides associates with a shift from a mesenchymal to an epithelial phenotype. Drug resistance, tumor hypoxia and tumor acidosis are critical obstacles in cancer management. We investigate the biological significance of glycosphingolipids in cellular responses to chemotherapeutic agents, hypoxia, and acidosis in OC cells. For instance, do chemo-resistant and -sensitive cells have different GSL profiles, does sustained exposure to drugs, hypoxia, and acidosis alter the GSL profile, and do cells from primary and metastatic tumors have a different GSL profile? The current results suggest that GSL modulate cellular responses to these stressors.

Beside the functional role of integrin-alpha2 glycosylation in ovarian cancer metastasis to the omentum and peritoneum, we are dissecting the endogenous and exogenous protein glycosylation (e.g. for E-cadherin) in various cancer cell line models (glycol-gene knock-outs, glycoprotein knock-ins, and mutated glyco-sites) during drug resistance acquisition and at metastases in ex vivo models and in vivo tumor xenografts.

 

Clinical Research and Trials

A more detailed overview on clinical trials is given elsewhere.

 

Selected Collaborations/Network

Interdisciplinary project to establish 3D-reconstructed functional omentum model to study omental metastasis of ovarian cancer and the underlying mechanisms (Uwe Pieles, FHNW Muttenz; Barbara Rothen-Rutishauser, Institute Adolphe Merkle, Fribourg; Ivan Martin, DBM, USB, Basel)

Interdisciplinary and interinstitutional project aimed at the molecular dissection of melanoma, ovarian cancer, and AML in order to genetically and molecularly dissect the tumors on single-cell level and to support clinicians in the best choice of therapy (ETH Zurich, Roche AG Schweiz)

Zebrafish embryo tumor xenografts (Claudia Lengerke, DBM, USB, Basel)

Investigation of OC metastasis in mouse models and design of radionuclid- and drug-coupled antibodies (Paul Scherrer Institute PSI; Jürgen Grünberg, Villingen, Switzerland)

Single Cell Technologies (Christian Beisel, ETH Basel), Franziska Singer (NEXUS))Analysis of glycosylated key cell surface proteins in metastasis (Daniel Kolarich, Arun Everest-Dass, Mark von Itzstein, Griffith University, Gold Coast, Australia) Role of mesothelin in ovarian cancer progression and metastasis (Leonor David, Porto, Portugal)

A feasibility study for investigating circulating tumor DNA (ctDNA) exposure in peripheral blood using a novel process (Quantgene Inc., Delaware Corporation, Berkeley, CA, USA)

Ovarian cancer stem cell markers and relation with histopathological parameters and patients’ prognosis (Ugo Cavallaro, Milan, Italy)

The biology of E-cadherin glycosylation (Henrik Clausen, Adnan Halim, University of Copenhagen, Copenhagen, Denmark)

Impact of integrin glycosylation in mouse metastatic xenograft models (Tobias Lange, University Medical Center Hamburg-Eppendorf, Hamburg, Germany)

Elucidiate molecular mechanisms of ascites development (Jan Hengstler, Leibniz Research Centre for Working Environment and Human Factors, Dortmund)

 

Specilities and Ressources

We have a large biobank with blood, tissue (frozen and embedded, TMA, ascites, urine samples, and primary tumor cells (frozen) from over 3’000 patients of 3 different locations (Sydney AUS, Zurich and Basel), including matched and longitudinal samples.

Our research laboratory has methodological expertise in molecular and translational cancer biology, glycobiology, and drug resistance; and employs modern lab technologies including CRISPR-Cas9-genome editing (silencing, activation, knock-out, knock-in, and library screens), fluorescence and live cell imaging, cultivation of primary cultures, zebrafish embryo tumor xenografts, and standard technologies such as fluorescence activated cell sorting.

 

Current Grants and Support

  • Swiss GO Trial Group (2019-2024; MATAO trial; MAintenance Therapy with Aromatase inhibitor in epithelial Ovarian cancer: a Randomized Double-blinded Placebo-controlled Phase III Trial)
  • MATAO trial; MAintenance Therapy with Aromatase inhibitor in epithelial Ovarian cancer: a Randomized Double-blinded Placebo-controlled Phase III Trial (supported by a.o. Helsana Krankenkasse; Krebsforschung Schweiz, Anticancer Fund/Reliable Cancer Therapies, Belgium/Switzerland; AGO Deutschland; Stiftung Fürstlicher Kommerzienrat Giudo Feger, Liechtenstein)
  • PHRT ETH Pioneer Project Grant (2020-2021; dissect longitudinal evolutionary trajectories in ovarian cancer patients using integrated proteogenomics)
  • FreeNovation Novartis (2020-2021; An approach towards single cell glycomics)
  • Swiss National Science Foundation SNF (Sinergia CRSII5_171037-1, 2018-2021; the underestimated role of the human omentum in metastatic spread)
  • Krebsforschung Schweiz (2017-2021; functional characterization of bisecting GlcNAc-dependent signalling pathways for the intervention of serous ovarian cancer omental metastasis)
  • Wilhelm Sander-Stiftung (2019-2020; Der Einfluss von Glykosphingolipiden auf molekulare und zelluläre Wirkmechanismen beim metastasierenden Ovarialkarzinom)

 

News and Opportunities

Paper “Outcome in serous ovarian cancer is not associated with LATS expression by Montavon et al) published (10/2019)

FreeNovation Grant “an approach towards single cell glycomics” to Ch Beisel (ETH Basel) and F. Jacob (OCR, DBM) (9/2019)

EACR Travel Fellowship “Glycosphingolipids (GSLs) study in ovarian cancer samples by direct visualization of GSLs with the novel MALDI imaging in matched collected SNAP frozen tissue sample” to C. Cumin (OCR, DBM (8/2019)

Best Poster Award to Y-L “Eddie” Huang (OCR, DBM) (29th Joint Glycobiology Meeting, Gent, Belgium, 10/2018)

 

 

 

 

 

 

Figure: MGAT3 transcription start site is hypermethylated (black circles) in OVCAR8 and poorly methylated (white) in OVCAR4 and BG1 cells (A) Demethylation by 5-Aza in hypermethylated OVCAR8 recovers MGAT3 expression (B) and bisecting GlcNAc expression (C: red arrow in insert). Boxplot of MGAT3 expression in TCGA PANCAN12 data set (n=3587): lowest expression in head and neck squamous cell cancer (top) to highest in ovarian serious cystadenocarcinoma (red frame) (D). Kaplan-Meier: low MGAT3 expression (grey line) associates with poor survival (various cancers combined) (E). Some high-grade serous ovarian cancer patients have low MGAT3 expression (grey) and are “long-term survivors” (F). Kohler et al., 2016.