Patient-derived tumor organoids: a new avenue for preclinical research and precision medicine in oncology.

Over the past decade, the emergence of patient-derived tumor organoids (PDTOs) has broadened the repertoire of preclinical models and progressively revolutionized three-dimensional cell culture in oncology. PDTO can be grown from patient tumor samples with high efficiency and faithfully recapitulates the histological and molecular characteristics of the original tumor. Therefore, PDTOs can serve as invaluable tools in oncology research, and their translation to clinical practice is exciting for the future of precision medicine in oncology. In this review, we provide an overview of methods for establishing PDTOs and their various applications in cancer research, starting with basic research and ending with the identification of new targets and preclinical validation of new anticancer compounds and precision medicine. Finally, we highlight the challenges associated with the clinical implementation of PDTO, such as its representativeness, success rate, assay speed, and lack of a tumor microenvironment. Technological developments and autologous cocultures of PDTOs and stromal cells are currently ongoing to meet these challenges and optimally exploit the full potential of these models. The use of PDTOs as standard tools in clinical oncology could lead to a new era of precision oncology in the coming decade.

The OVAREX study: Establishment of ex vivo ovarian cancer models to validate innovative therapies and to identify predictive biomarkers.

BACKGROUND: Ovarian cancer is the first cause of death from gynecological malignancies mainly due to development of chemoresistance. Despite the emergence of PARP inhibitors, which have revolutionized the therapeutic management of some of these ovarian cancers, the 5-year overall survival rate remains around 45%. Therefore, it is crucial to develop new therapeutic strategies, to identify predictive biomarkers and to predict the response to treatments. In this context, functional assays based on patient-derived tumor models could constitute helpful and relevant tools for identifying efficient therapies or to guide clinical decision making. METHOD: The OVAREX study is a single-center non-interventional study which aims at investigating the feasibility of establishing in vivo and ex vivo models and testing ex vivo models to predict clinical response of ovarian cancer patients. Patient-Derived Xenografts (PDX) will be established from tumor fragments engrafted subcutaneously into immunocompromised mice. Explants will be generated by slicing tumor tissues and Ascites-Derived Spheroids (ADS) will be isolated following filtration of ascites. Patient-derived tumor organoids (PDTO) will be established after dissociation of tumor tissues or ADS, cell embedding into extracellular matrix and culture in specific medium. Molecular and histological characterizations will be performed to compare tumor of origin and paired models. Response of ex vivo tumor-derived models to conventional chemotherapy and PARP inhibitors will be assessed and compared to results of companion diagnostic test and/or to the patient's response to evaluate their predictive value. DISCUSSION: This clinical study aims at generating PDX and ex vivo models (PDTO, ADS, and explants) from tumors or ascites of ovarian cancer patients who will undergo surgical procedure or paracentesis. We aim at demonstrating the predictive value of ex vivo models for their potential use in routine clinical practice as part of precision medicine, as well as establishing a collection of relevant ovarian cancer models that will be useful for the evaluation of future innovative therapies. TRIAL REGISTRATION: The clinical trial has been validated by local research ethic committee on January 25th 2019 and registered at ClinicalTrials.gov with the identifier NCT03831230 on January 28th 2019, last amendment v4 accepted on July 18, 2023.

Comparative analysis of response to treatments and molecular features of tumor-derived organoids versus cell lines and PDX derived from the same ovarian clear cell carcinoma.

BACKGROUND: In the era of personalized medicine, the establishment of preclinical models of cancer that faithfully recapitulate original tumors is essential to potentially guide clinical decisions. METHODS: We established 7 models [4 cell lines, 2 Patient-Derived Tumor Organoids (PDTO) and 1 Patient-Derived Xenograft (PDX)], all derived from the same Ovarian Clear Cell Carcinoma (OCCC). To determine the relevance of each of these models, comprehensive characterization was performed based on morphological, histological, and transcriptomic analyses as well as on the evaluation of their response to the treatments received by the patient. These results were compared to the clinical data. RESULTS: Only the PDX and PDTO models derived from the patient tumor were able to recapitulate the patient tumor heterogeneity. The patient was refractory to carboplatin, doxorubicin and gemcitabine, while tumor cell lines were sensitive to these treatments. In contrast, PDX and PDTO models displayed resistance to the 3 drugs. The transcriptomic analysis was consistent with these results since the models recapitulating faithfully the clinical response grouped together away from the other classical 2D cell culture models. We next investigated the potential of drugs that have not been used in the patient clinical management and we identified the HDAC inhibitor belinostat as a potential effective treatment based on PDTO response. CONCLUSIONS: PDX and PDTO appear to be the most relevant models, but only PDTO seem to present all the necessary prerequisites for predictive purposes and could constitute relevant tools for therapeutic decision support in the context of these particularly aggressive cancers refractory to conventional treatments.

The TRIPLEX study: use of patient-derived tumor organoids as an innovative tool for precision medicine in triple-negative breast cancer.

BACKGROUND: Triple negative breast cancers (TNBC) account for approximately 15% of all breast cancers and are associated with a shorter median survival mainly due to locally advanced tumor and high risk of metastasis. The current neoadjuvant treatment for TNBC consists of a regimen of immune checkpoint blocker and chemotherapy (chemo-ICB). Despite the frequent use of this combination for TNBC treatment, moderate results are observed and its clinical benefit in TNBC remains difficult to predict. Patient-derived tumor organoids (PDTO) are 3D in vitro cellular structures obtained from patient's tumor samples. More and more evidence suggest that these models could predict the response of the tumor from which they are derived. PDTO may thus be used as a tool to predict chemo-ICB efficacy in TNBC patients. METHOD: The TRIPLEX study is a single-center observational study conducted to investigate the feasibility of generating PDTO from TNBC and to evaluate their ability to predict clinical response. PDTO will be obtained after the dissociation of biopsies and embedding into extra cellular matrix. PDTO will be cultured in a medium supplemented with growth factors and signal pathway inhibitors. Molecular and histological analyses will be performed on established PDTO lines to validate their phenotypic proximity with the original tumor. Response of PDTO to chemo-ICB will be assessed using co-cultures with autologous immune cells collected from patient blood samples. PDTO response will finally be compared with the response of the patient to evaluate the predictive potential of the model. DISCUSSION: This study will allow to assess the feasibility of using PDTO as predictive tools for the evaluation of the response of TNBC patients to treatments. In the event that PDTO could faithfully predict patient response in clinically relevant time frames, a prospective clinical trial could be designed to use PDTO to guide clinical decision. This study will also permit the establishment of a living biobank of TNBC PDTO usable for future innovative strategies evaluation. TRIAL REGISTRATION: The clinical trial (version 1.2) has been validated by local research ethic committee on December 30th 2021 and registered at ClinicalTrials.gov with the identifier NCT05404321 on June 3rd 2022, version 1.2.

Involvement of lncRNAs in cancer cells migration, invasion and metastasis: cytoskeleton and ECM crosstalk.

Cancer is the main cause of death worldwide and metastasis is a major cause of poor prognosis and cancer-associated mortality. Metastatic conversion of cancer cells is a multiplex process, including EMT through cytoskeleton remodeling and interaction with TME. Tens of thousands of putative lncRNAs have been identified, but the biological functions of most are still to be identified. However, lncRNAs have already emerged as key regulators of gene expression at transcriptional and post-transcriptional level to control gene expression in a spatio-temporal fashion. LncRNA-dependent mechanisms can control cell fates during development and their perturbed expression is associated with the onset and progression of many diseases including cancer. LncRNAs have been involved in each step of cancer cells metastasis through different modes of action. The investigation of lncRNAs different roles in cancer metastasis could possibly lead to the identification of new biomarkers and innovative cancer therapeutic options.

ORGAVADS: establishment of tumor organoids from head and neck squamous cell carcinoma to assess their response to innovative therapies.

BACKGROUND: Radiotherapy is one of the cornerstones of the treatment of Head and Neck Squamous Cell Carcinomas (HNSCC). However, radioresistance is associated with a high risk of recurrence. To propose strategies (such as combinations with drugs) that could over intrinsic radioresistance, it is crucial to predict the response to treatment. Patient-Derived Tumor Organoids (PDTO) are in vitro tridimensional microtumors obtained from patient' own cancer samples. They have been shown to serve as reliable surrogates of the tumor response in patients. METHODS: The ORGAVADS study is a multicenter observational trial conducted to investigate the feasibility of generating and testing PDTO derived from HNSCC for the evaluation of sensitivity to treatments. PDTO are obtained after dissociation of resected tumors remaining from tissues necessary for the diagnosis. Embedding of tumor cells is then performed in extracellular matrix and culture in medium supplemented with growth factors and inhibitors. Histological and immunohistochemical characterizations are performed to validate the resemblance between PDTO and their original tumor. Response of PDTO to chemotherapy, radiotherapy and innovating combinations are assessed, as well as response to immunotherapy using co-cultures of PDTO with autologous immune cells collected from patient blood samples. Transcriptomic and genetic analyses of PDTO allow validation of the models compared to patients' own tumor and identification of potential predictive biomarkers. DISCUSSION: This study is designed to develop PDTO models from HNSCC. It will allow comparing the response of PDTO to treatment and the clinical response of the patients from whom they are derived. Our aim is to study the PDTO ability to predict the clinical response to treatment for each patient in view of a personalized medicine as well as to establish a collection of HNSCC models that will be useful for future innovative strategies evaluation. TRIAL REGISTRATION: NCT04261192, registered February 7, 2020, last amendment v4 accepted on June, 2021.

[Patient-derived tumor organoids (or tumoroid), a growing preclinical model for oncology]. / Les tumoroïdes, modèles précliniques en plein essor pour l'oncologie.

The recent emergence of tumor organoid cultures, or tumoroids, has enriched the repertoire of preclinical models in oncology. These microtumors are obtained in vitro by including cells from patient tumor samples in an extracellular matrix and cultured in specific media. Very close to the tumor of origin, tumoroids can be amplified fairly rapidly from a small quantity of tissue, established with high success rate for most tumor types, easily genetically engineered, and stored in biobanks. Tumoroids thus offer numerous possibilities in terms of basic research, such as the study of carcinogenesis or mechanisms of chemoresistance, but also the identification of new targets and preclinical validation of new anti-cancer compounds or personalized medicine. Technological developments and enrichment of tumoroids with other cell types are currently ongoing to optimally exploit the full potential of these models.

Title: Les tumoroïdes, modèles précliniques en plein essor pour l'oncologie. Abstract: La récente émergence des cultures d'organoïdes tumoraux, ou tumoroïdes, a permis d'enrichir le répertoire des modèles précliniques en oncologie. Très proches de la tumeur dont elles dérivent, ces microtumeurs offrent de nombreuses possibilités en termes de recherche fondamentale, telles que l'étude de la carcinogenèse ou de la chimioré-sistance, de validation préclinique de nouvelles molécules à visée anticancéreuse, ou encore de personnalisation des traitements. Divers développements techniques et l'enrichissement des tumoroïdes par l'addition d'autres types cellulaires sont actuellement en cours pour améliorer la pertinence de ces modèles et exploiter de façon optimale leur remarquable potentiel.

[Patient-derived tumor organoids (or tumoroid) as valuable precision medicine tools]. / Les organoïdes dérivés de tumeurs (ou tumoroïdes), des outils de choix pour la médecine de précision en oncologie.

Review of literature shows that it is possible to establish tumor-derived organoids, or tumoroids, from almost any type of tumor, and that these "micro-tumors" could be used to develop functional assays allowing the prediction of the patient response to treatments and/or the identification of predictive molecular signatures associated with the development of these therapies. Although it is still essential to optimize culture conditions to promote and accelerate the establishment of tumoroids, or to recapitulate tumor microenvironment, many applications are now possible in the field of prediction of response to treatments and in guiding therapeutic decision-making. Using tumoroids as standard tools in clinical oncology could make precision oncology enter a new era in the coming decade. Numerous ongoing research and clinical trials conducted throughout the world aim to validate the interest of this approach.

Title: Les organoïdes dérivés de tumeurs (ou tumoroïdes), des outils de choix pour la médecine de précision en oncologie. Abstract: Il est désormais possible d'établir des tumoroïdes à partir de presque tout type de tumeur, notamment en vue de la mise en place de tests fonctionnels prédictifs et/ou de l'identification de signatures moléculaires prédictives. Bien que l'optimisation des conditions de culture ou la complexification du micro-environnement des tumoroïdes soit encore nécessaire, de nombreuses applications sont déjà envisageables dans le domaine de la prédiction de la réponse aux traitements et de l'orientation de la décision thérapeutique. Par l'introduction de leur utilisation en clinique, l'oncologie de précision pourrait bien entrer dans une nouvelle ère dans le courant de la décennie à venir.

Perioperative treatment in resectable gastric cancer with spartalizumab in combination with fluorouracil, leucovorin, oxaliplatin and docetaxel (FLOT): a phase II study (GASPAR).

BACKGROUND: Perioperative chemotherapy and surgery are a standard of care for patients with resectable gastric or gastroesophageal junction (GEJ) adenocarcinoma. However, the prognosis remains poor for this population. The FLOT (fluorouracil, leucovorin, oxaliplatin, and docetaxel) regimen is considered as the new standard chemotherapy regimen for perioperative strategy, despite associated with a 5-year overall survival rate (OS) amounting 45% following radical surgery. Immunotherapy with antibodies that inhibit PD-1/ PD-L1 interaction has recently emerged as a new treatment option with promising and encouraging early trial results for patients with advanced or metastatic gastric or GEJ adenocarcinoma. Currently, no trials have investigated the impact of perioperative immunotherapy in combination with chemotherapy for resectable gastric or GEJ adenocarcinoma. METHODS: GASPAR trial is a multicenter open-label, nonrandomized, phase II trial to evaluate the efficacy and safety of Spartalizumab in combination with the FLOT regimen as perioperative treatment for resectable gastric or GEJ adenocarcinoma. The main endpoint is the proportion of patients with pathological complete regression (pCR) in the primary tumour after preoperative treatment. Systemic treatment will include a pre-operative neoadjuvant and a post-operative adjuvant treatment, during which FLOT regimen will be administered every two weeks for 4 cycles and Spartalizumab every four weeks for 2 cycles. For patients with confirmed tumor resectability on imaging assessment, surgery will be realized within 4-6 weeks after the last dose of preoperative chemotherapy. Post-operative systemic treatment will then be initiated within 4-10 weeks after surgery. Using a Simon's two-stage design, up to 67 patients will be enrolled, including 23 in the first stage. DISCUSSION: Currently, no trials have investigated the impact of immunotherapy in combination with FLOT chemotherapy as perioperative treatment for resectable gastric or GEJ adenocarcinoma. Some studies have suggested a change in the tumor immune micro-environment following neoadjuvant chemotherapy in this setting, reinforcing the relevance to propose a phase II trial evaluating efficacy and safety of Spartalizumab in combination with perioperative chemotherapy, with the aim of improving treatment efficacy and survival outcomes. TRIAL REGISTRATION: NCT04736485, registered February, 3, 2021.

A phase II study of Navitoclax (ABT-263) as single agent in women heavily pretreated for recurrent epithelial ovarian cancer: The MONAVI - GINECO study.

BACKGROUND: There are limited treatment options for ovarian cancer patients with early relapse after platinum chemotherapy. In preclinical studies, we previously demonstrated the promising activity of ABT-737, a Bcl-2/Bcl-xL anti-apoptotic protein inhibitor, in chemo-resistant ovarian cancer cells and tumors, suggesting its potential activity in platinum-resistant patients. METHODS: We conducted a prospective multicenter single-arm phase II study to assess the efficacy of Navitoclax (orally available ABT-737 analogue) monotherapy in 46 heavily pretreated (2-12 lines, median = 4) patients with high-grade serous platinum-resistant ovarian tumors. Navitoclax was administered at the daily dose of 150 mg during a lead-in period (7-14 days) and then increased to 250 mg daily in the absence of dose-limiting thrombocytopenia (

A new pancreatic adenocarcinoma-derived organoid model of acquired chemoresistance to FOLFIRINOX: First insight of the underlying mechanisms.

BACKGROUND INFORMATION: Although improvements have been made in the management of pancreatic adenocarcinoma (PDAC) during the past 20 years, the prognosis of this deadly disease remains poor with an overall 5-year survival under 10%. Treatment with FOLFIRINOX, a combined regimen of 5-fluorouracil, irinotecan (SN-38) and oxaliplatin, is nonetheless associated with an excellent initial tumour response and its use has allowed numerous patients to go through surgery while their tumour was initially considered unresectable. These discrepancies between initial tumour response and very low long-term survival are the consequences of rapidly acquired chemoresistance and represent a major therapeutic frontier. To our knowledge, a model of resistance to the combined three drugs has never been described due to the difficulty of modelling the FOLFIRINOX protocol both in vitro and in vivo. Patient-derived tumour organoids (PDO) are the missing link that has long been lacking in the wide range of epithelial cancer models between 2D adherent cultures and in vivo xenografts. In this work we sought to set up a model of PDO with resistance to FOLFIRINOX regimen that we could compare to the paired naive PDO. RESULTS: We first extrapolated physiological concentrations of the three drugs using previous pharmacodynamics studies and bi-compartmental elimination models of oxaliplatin and SN-38. We then treated PaTa-1818x naive PDAC organoids with six cycles of 72 h-FOLFIRINOX treatment followed by 96 h interruption. Thereafter, we systematically compared treated organoids to PaTa-1818x naive organoids in terms of growth, proliferation, viability and expression of genes involved in cancer stemness and aggressiveness. CONCLUSIONS: We reproductively obtained resistant organoids FoxR that significantly showed less sensitivity to FOLFORINOX treatment than the PaTa-1818x naive organoids from which they were derived. Our resistant model is representative of the sequential steps of chemoresistance observed in patients in terms of growth arrest (proliferation blockade), residual disease (cell quiescence/dormancy) and relapse. SIGNIFICANCE: To our knowledge, this is the first genuine in vitro model of resistance to the three drugs in combined therapy. This new PDO model will be a great asset for the discovery of acquired chemoresistance mechanisms, knowledge that is mandatory before offering new therapeutic strategies for pancreatic cancer.

Drug Repurposing: Deferasirox Inhibits the Anti-Apoptotic Activity of Mcl-1.

INTRODUCTION: With the aim of repositioning commercially available drugs for the inhibition of the anti-apoptotic myeloid cell leukemia protein, Mcl-1, implied in various cancers, five molecules, highlighted from a published theoretical screening, were selected to experimentally validate their affinity toward Mcl-1. RESULTS: A detailed NMR study revealed that only two of the five tested drugs, Torsemide and Deferasirox, interacted with Mcl-1. NMR data analysis allowed the complete characterization of the binding mode of both drugs to Mcl-1, including the estimation of their affinity for Mcl-1. Biological assays evidenced that the biological activity of Torsemide was lower as compared to the Deferasirox, which was able to efficiently and selectively inhibit the anti-apoptotic activity of Mcl-1. Finally, docking and molecular dynamics led to a 3D model for the Deferasirox:Mcl-1 complex and revealed the positioning of the drug in the Mcl-1 P2/P3 pockets as well as almost all synthetic Mcl-1 inhibitors. Interestingly, contrary to known synthetic Mcl-1 inhibitors which interact through Arg263, Deferasirox, establishes a salt bridge with Lys234. CONCLUSION: Deferasirox could be a potential candidate for drug repositioning as Mcl-1 inhibitor.

Structural revision of the Mcl-1 inhibitor MIM1: synthesis and biological studies on ovarian cancer cells with evaluation of designed analogues.

In the area of cancer research, the development of new and potent inhibitors of anti-apoptotic proteins is a very active and promising topic. The small molecule MIM1 has been reported earlier as one of the first selective inhibitors of the anti-apoptotic protein Mcl-1. In the present paper, we first revised the structure of this molecule based on extensive physicochemical analyses. Then we designed and synthesized a focused library of analogues for the corrected structure of MIM1. Next, these molecules were subjected to a panel of in cellulo biological studies, allowing the identification of dual Bcl-xL/Mcl-1 inhibitors, as well as selective Mcl-1 inhibitors. These results have been complemented by fluorescence polarization assays with the Mcl-1 protein. Preliminary structure-activity relationships were discussed and extensive molecular modelling studies allowed us to propose a rationale for the biological activity of this series of new inhibitors, in particular for the selectivity of inhibition of Mcl-1 versus Bcl-xL.

The lncRNA 'UCA1' modulates the response to chemotherapy of ovarian cancer through direct binding to miR-27a-5p and control of UBE2N levels.

Ovarian cancer (OC) is the leading cause of death in patients with gynecologic cancers. Due to late diagnosis and resistance to chemotherapy, the 5-year survival rate in patients with OC is below 40%. We observed that UCA1, a lncRNA previously reported to play an oncogenic role in several malignancies, is overexpressed in the chemoresistant OC cell line OAW42-R compared to their chemotherapy-sensitive counterpart OAW42. Additionally, UCA1 overexpression was related to poor prognosis in two independent patient cohorts. Currently, the molecular mechanisms through which UCA1 acts in OC are poorly understood. We demonstrated that downregulation of the short isoform of UCA1 sensitized OC cells to cisplatin and that UCA1 acted as competing endogenous RNA to miR-27a-5p. Upon UCA1 downregulation, miR-27a-5p downregulated its direct target UBE2N leading to the upregulation of BIM, a proapoptotic protein of the Bcl2 family. The upregulation of BIM is the event responsible for the sensitization of OC cells to cisplatin. In order to model response to therapy in patients with OC, we used several patient-derived organoid cultures, a model faithfully mimicking patient's response to therapy. Inhibition of UBE2N sensitized patient-derived organoids to platinum salts. In conclusion, response to treatment in patients with OC is regulated by the UCA1/miR-27a-5p/UBE2N axis, where UBE2N inhibition could potentially represent a novel therapeutic strategy to counter chemoresistance in OC.

Identifying patients eligible for PARP inhibitor treatment: from NGS-based tests to 3D functional assays.

Within the past few years, poly (ADP-ribose) polymerase inhibitors (PARPi) have been added to the standard of care for cancer patients, mainly for those exhibiting specific genomic alterations in the homologous recombination (HR) pathway. Until now, patients who are eligible to receive PARPi have been identified using next-generation sequencing (NGS) of gene panels. However, NGS analyses do have some limitations, with a subset of patients with negative NGS-based results can exhibit a clinical benefit, responding positively to PARPi, despite the failure to detect dynamic and predictive biomarkers such as mutated BRCA1/2 genes. Furthermore, the sequencing of initial tumour does not allow to detect reversions or secondary mutations that can restore proficient HR and lead to PARPi resistance. Therefore, it is crucial to better identify patients who are likely to benefit from PARPi treatment. In this context, tumour models such as patient-derived xenografts or tumour-derived organoids could help to guide clinicians in their decision making as these models accurately mimic phenotypic and genetic tumour heterogeneity, and could reflect treatment response in an integrative manner. In this Perspective article, we provide an overview of the currently available NGS-based tests that enable the identification of patients who might benefit from PARPi, and outline breakthroughs and discoveries to expand this selection using 3D functional assays. Combining NGS with functional assays could facilitate the efficient identification of patients, thereby improving patient survival.

Bim, Puma and Noxa upregulation by Naftopidil sensitizes ovarian cancer to the BH3-mimetic ABT-737 and the MEK inhibitor Trametinib.

Ovarian cancer represents the first cause of mortality from gynecologic malignancies due to frequent chemoresistance occurrence. Increasing the [BH3-only Bim, Puma, Noxa proapoptotic]/[Bcl-xL, Mcl-1 antiapoptotic] proteins ratio was proven to efficiently kill ovarian carcinoma cells and development of new molecules to imbalance Bcl-2 member equilibrium are strongly required. Drug repurposing constitutes an innovative approach to rapidly develop therapeutic strategies through exploitation of established drugs already approved for the treatment of noncancerous diseases. This strategy allowed a renewed interest for Naftopidil, an α1-adrenergic receptor antagonist commercialized in Japan for benign prostatic hyperplasia. Naftopidil was reported to decrease the incidence of prostate cancer and its derivative was described to increase BH3-only protein expression in some cancer models. Based on these arguments, we evaluated the effects of Naftopidil on ovarian carcinoma and showed that Naftopidil reduced cell growth and increased the expression of the BH3-only proteins Bim, Puma and Noxa. This effect was independent of α1-adrenergic receptors blocking and involved ATF4 or JNK pathway depending on cellular context. Finally, Naftopidil-induced BH3-only members sensitized our models to ABT-737 and Trametinib treatments, in vitro as well as ex vivo, in patient-derived organoid models.

Functional miRNA Screening Identifies Wide-ranging Antitumor Properties of miR-3622b-5p and Reveals a New Therapeutic Combination Strategy in Ovarian Tumor Organoids.

Novel therapeutic strategies are urgently required for the clinical management of chemoresistant ovarian carcinoma, which is the most lethal of the gynecologic malignancies. miRNAs hold promise because they play a critical role in determining the cell phenotype by regulating several hundreds of targets, which could constitute vulnerabilities of cancer cells. A combination of gain-of-function miRNA screening and real-time continuous cell monitoring allows the identification of miRNAs with robust cytotoxic effects in chemoresistant ovarian cancer cells. Focusing on miR-3622b-5p, we show that it induces apoptosis in several ovarian cancer cell lines by both directly targeting Bcl-xL and EGFR-mediating BIM upregulation. miR-3622b-5p also sensitizes cells to cisplatin by inhibiting Bcl-xL in ovarian cancer cell lines escaping BIM induction. miR-3622b-5p also exerts antimigratory capacities by targeting both LIMK1 and NOTCH1. These wide-ranging antitumor properties of miR-3622b-5p in ovarian cancer cells are mimicked by the associations of pharmacologic inhibitors targeting these proteins. The combination of an EGFR inhibitor together with a BH3-mimetic molecule induced a large decrease in cell viability in a panel of ovarian cancer cell lines and several ovarian patient-derived tumor organoids, suggesting the value of pursuing such a combination therapy in ovarian carcinoma. Altogether, our work highlights the potential of phenotype-based miRNA screening approaches to identify lethal interactions which might lead to new drug combinations and clinically applicable strategies.

Structure-guided design of pyridoclax derivatives based on Noxa / Mcl-1 interaction mode.

Protein-protein interactions are attractive targets because they control numerous cellular processes. In oncology, apoptosis regulating Bcl-2 family proteins are of particular interest. Apoptotic cell death is controlled via PPIs between the anti-apoptotic proteins hydrophobic groove and the pro-apoptotic proteins BH3 domain. In ovarian carcinoma, it has been previously demonstrated that Bcl-xL and Mcl-1 cooperate to protect tumor cells against apoptosis. Moreover, Mcl-1 is a key regulator of cancer cell survival and is a known resistance factor to Bcl-2/Bcl-xL pharmacological inhibitors making it an attractive therapeutic target. Here, using a structure-guided design from the oligopyridine lead Pyridoclax based on Noxa/Mcl-1 interaction we identified a new derivative, active at lower concentration as compared to Pyridoclax. This new derivative selectively binds to the Mcl-1 hydrophobic groove and releases Bak and Bim from Mcl-1 to induce cell death and sensitize cancer cells to Bcl-2/Bcl-xL targeting strategies.

Inactivation of the Kinase Domain of CDK10 Prevents Tumor Growth in a Preclinical Model of Colorectal Cancer, and Is Accompanied by Downregulation of Bcl-2.

Cyclin-dependent kinase 10 (CDK10), a CDC2-related kinase, is highly expressed in colorectal cancer. Its role in the pathogenesis of colorectal cancer is unknown. This study examines the function of CDK10 in colorectal cancer, and demonstrates its role in suppressing apoptosis and in promoting tumor growth in vitro and in vivo Modulation of CDK10 expression in colorectal cancer cell lines demonstrates that CDK10 promotes cell growth, reduces chemosensitivity and inhibits apoptosis by upregulating the expression of Bcl-2. This effect appears to depend on its kinase activity, as kinase-defective mutant colorectal cancer cell lines have an exaggerated apoptotic response and reduced proliferative capacity. In vivo, inhibiting CDK10 in colorectal cancer following intratumoral injections of lentivirus-mediated CDK10 siRNA in a patient-derived xenograft mouse model demonstrated its efficacy in suppressing tumor growth. Furthermore, using a tissue microarray of human colorectal cancer tissues, the potential for CDK10 to be a prognostic biomarker in colorectal cancer was explored. In tumors of individuals with colorectal cancer, high expression of CDK10 correlates with earlier relapse and shorter overall survival. The findings of this study indicate that CDK10 plays a role in the pathogenesis in colorectal cancer and may be a potential therapeutic target for treatment. Mol Cancer Ther; 16(10); 2292-303. ©2017 AACR.

Exosomes confer pro-survival signals to alter the phenotype of prostate cells in their surrounding environment.

Prostate cancer (PCa) is the most frequently diagnosed cancer in men. Current research on tumour-related extracellular vesicles (EVs) suggests that exosomes play a significant role in paracrine signaling pathways, thus potentially influencing cancer progression via multiple mechanisms. In fact, during the last decade numerous studies have revealed the role of EVs in the progression of various pathological conditions including cancer. Moreover, differences in the proteomic, lipidomic, and cholesterol content of exosomes derived from PCa cell lines versus benign prostate cell lines confirm that exosomes could be excellent biomarker candidates. As such, as part of an extensive proteomic analysis using LCMS we previously described a potential role of exosomes as biomarkers for PCa. Current evidence suggests that uptake of EV's into the local tumour microenvironment encouraging us to further examine the role of these vesicles in distinct mechanisms involved in the progression of PCa and castration resistant PCa. For the purpose of this study, we hypothesized that exosomes play a pivotal role in cell-cell communication in the local tumour microenvironment, conferring activation of numerous survival mechanisms during PCa progression and development of therapeutic resistance. Our in vitro results demonstrate that PCa derived exosomes significantly reduce apoptosis, increase cancer cell proliferation and induce cell migration in LNCaP and RWPE-1 cells. In conjunction with our in vitro findings, we have also demonstrated that exosomes increased tumor volume and serum PSA levels in vivo when xenograft bearing mice were administered DU145 cell derived exosomes intravenously. This research suggests that, regardless of androgen receptor phenotype, exosomes derived from PCa cells significantly enhance multiple mechanisms that contribute to PCa progression.