Quantification of cell death and proliferation of patient-derived ovarian cancer organoids through 3D imaging and image analysis

Patient-derived organoids (PDOs) are ideal ex vivo model systems to study cancer progression and drug resistance mechanisms. Here, we present a protocol for measuring drug efficacy in three-dimensional (3D) high-grade serous ovarian cancer PDO cultures through quantification of cytotoxicity using propidium iodide incorporation in dead cells. We also provide detailed steps to analyze proliferation of PDOs using the Ki67 biomarker. We describe steps for sample processing, immunofluorescent staining, high-throughput confocal imaging, and image-based quantification for 3D cultures. For complete details on the use and execution of this protocol, please refer to Lahtinen et al. (2023).1.

Activation of invasion by oncogenic reprogramming of cholesterol metabolism via increased NPC1 expression and macropinocytosis

Cancer cells are dependent on cholesterol, and they possess strictly controlled cholesterol homeostasis mechanisms. These allow them to smoothly switch between cholesterol synthesis and uptake to fulfill their needs and to adapt environmental changes. Here we describe a mechanism of how cancer cells employ oncogenic growth factor signaling to promote uptake and utilization of extracellular cholesterol via Myeloid Zinc Finger 1 (MZF1)-mediated Niemann Pick C1 (NPC1) expression and upregulated macropinocytosis. Expression of p95ErbB2, highly oncogenic, standard-treatment resistant form of ErbB2 mobilizes lysosomes and activates EGFR, invasion and macropinocytosis. This is connected to a metabolic shift from cholesterol synthesis to uptake due to macropinocytosis-enabled flow of extracellular cholesterol. NPC1 increase facilitates extracellular cholesterol uptake and is necessary for the invasion of ErbB2 expressing breast cancer spheroids and ovarian cancer organoids, indicating a regulatory role for NPC1 in the process. The ability to obtain cholesterol as a byproduct of increased macropinocytosis allows cancer cells to direct the resources needed for the energy-consuming cholesterol synthesis towards other activities such as invasion. These results demonstrate that macropinocytosis is not only an alternative energy source for cancer cells but also an efficient way to provide building material, such as cholesterol, for its macromolecules and membranes.

Evolutionary states and trajectories characterized by distinct pathways stratify patients with ovarian high grade serous carcinoma

Ovarian high-grade serous carcinoma (HGSC) is typically diagnosed at an advanced stage, with multiple genetically heterogeneous clones existing in the tumors long before therapeutic intervention. Herein we integrate clonal composition and topology using whole-genome sequencing data from 510 samples of 148 patients with HGSC in the prospective, longitudinal, multiregion DECIDER study. Our results reveal three evolutionary states, which have distinct features in genomics, pathways, and morphological phenotypes, and significant association with treatment response. Nested pathway analysis suggests two evolutionary trajectories between the states. Experiments with five tumor organoids and three PI3K inhibitors support targeting tumors with enriched PI3K/AKT pathway with alpelisib. Heterogeneity analysis of samples from multiple anatomical sites shows that site-of-origin samples have 70% more unique clones than metastatic tumors or ascites. In conclusion, these analysis and visualization methods enable integrative tumor evolution analysis to identify patient subtypes using data from longitudinal, multiregion cohorts.

Kinase Inhibitors in the Treatment of Ovarian Cancer: Current State and Future Promises

Ovarian cancer is the deadliest gynecological cancer, the high-grade serous ovarian carcinoma (HGSC) being its most common and most aggressive form. Despite the latest therapeutical advancements following the introduction of vascular endothelial growth factor receptor (VEGFR) targeting angiogenesis inhibitors and poly-ADP-ribose-polymerase (PARP) inhibitors to supplement the standard platinum- and taxane-based chemotherapy, the expected overall survival of HGSC patients has not improved significantly from the five-year rate of 42%. This calls for the development and testing of more efficient treatment options. Many oncogenic kinase-signaling pathways are dysregulated in HGSC. Since small-molecule kinase inhibitors have revolutionized the treatment of many solid cancers due to the generality of the increased activation of protein kinases in carcinomas, it is reasonable to evaluate their potential against HGSC. Here, we present the latest concluded and on-going clinical trials on kinase inhibitors in HGSC, as well as the recent work concerning ovarian cancer patient organoids and xenograft models. We discuss the potential of kinase inhibitors as personalized treatments, which would require comprehensive assessment of the biological mechanisms underlying tumor spread and chemoresistance in individual patients, and their connection to tumor genome and transcriptome to establish identifiable subgroups of patients who are most likely to benefit from a given therapy.

Abstract 192: Ex vivo screening and analysis of novel effective treatments for ovarian cancer

Purpose: Ovarian cancer is the most lethal gynecological cancer. Histologically, about 90% of the ovarian cancers have epithelial origin and more than 75% are characterized as high-grade serous ovarian cancer (HGSOC). Despite having a good primary response to the standard platinum-taxane based chemotherapy, almost all HGSOC patients experience a relapsed disease. The 5-year survival rate of ovarian cancer is only 38% globally, indicating need for the development of novel efficient treatments to fight the resistance. Here we have established a personalized drug screening and evaluation platform using HGSOC patient samples and medicines approved for treatment of different types of cancers.

Methods: Tissues collected from ovarian cancer patients were grown as 3-dimensional (3D) ex vivo long-term tumor organoid cultures. Seven HGSOC cell lines were additionally grown as spheroids or as xenograft tumors to establish them as 3D tumor organoid cultures for drug efficiency evaluation. Cancer stemness and further classification of samples were determined via immunofluorescent staining with relevant antibodies (pax8, Ki67, acetylated tubulin, p53, cytokeratin-8) and consequent high-throughput imaging using the ImageXpress Micro Confocal microscope (Molecular Devices). The images were analyzed and quantified using MetaXpress software. Organoid growth and response to tested treatments was validated via invasive growth and survival assays. Both assays were used to monitor resistance of organoids towards cisplatin and carboplatin treatment and towards suggested potential new treatments. Cancer drugs were selected according to suggestions based on RNA seq, DNA and/or drug screenings done in cancer cell lines. A preclinical mouse model (in immunodeficient NOD/Shi-scid/IL-2Rγnull (NOG) mice) was set up to be used for in vivo validation by monitoring the tumor growth in response to the treatment.

Results: Currently, 20 patient tumor samples received from Turku University Hospital, Finland (KH, JH) have been cultured in 4 different culture media to obtain highest possible survival rates for each sample. Organoids from ovarian cancer cell lines are characterized for their resistance to increasing concentrations of platinum treatment. Notably, organoid analysis protocols and screening conditions have been setup for the high-throughput microscopy. These include organoid growth, survival, and invasiveness/aggressiveness. We are currently set up for screening organoids with the first drugs suggested by bioinformatics-based genetic pathway analysis and drug screening studies in cancer cell lines. The results of the screen will be presented. This study is a part of a large EU-funded ovarian cancer project DECIDER (https://www.deciderproject.eu/).

Citation Format: Aikaterini Skorda, Kaisa Huhtinen, Wojciech Senkowski, Krister Wennerberg, Sampsa Hautaniemi, Johanna Hynninen, Tuula Kallunki. Ex vivo screening and analysis of novel effective treatments for ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 192.

Non-lethal proteasome inhibition activates pro-tumorigenic pathways in multiple myeloma cells

Multiple myeloma (MM) is a haematological malignancy being characterized by clonal plasma cell proliferation in the bone marrow. Targeting the proteasome with specific inhibitors (PIs) has been proven a promising therapeutic strategy and PIs have been approved for the treatment of MM and mantle‐cell lymphoma; yet, while outcome has improved, most patients inevitably relapse. As relapse refers to MM cells that survive therapy, we sought to identify the molecular responses induced in MM cells after non‐lethal proteasome inhibition. By using bortezomib (BTZ), epoxomicin (EPOX; a carfilzomib‐like PI) and three PIs, namely Rub999, PR671A and Rub1024 that target each of the three proteasome peptidases, we found that only BTZ and EPOX are toxic in MM cells at low concentrations. Phosphoproteomic profiling after treatment of MM cells with non‐lethal (IC₁₀) doses of the PIs revealed inhibitor‐ and cell type‐specific readouts, being marked by the activation of tumorigenic STAT3 and STAT6. Consistently, cytokine/chemokine profiling revealed the increased secretion of immunosuppressive pro‐tumorigenic cytokines (IL6 and IL8), along with the inhibition of potent T cell chemoattractant chemokines (CXCL10). These findings indicate that MM cells that survive treatment with therapeutic PIs shape a pro‐tumorigenic immunosuppressive cellular and secretory bone marrow microenvironment that enables malignancy to relapse.