In this thesis, different preclinical strategies were explored aiming at the identification of putative novel therapies for prostate and bladder cancer. The first part of this thesis (Chapter 2 and... Show moreIn this thesis, different preclinical strategies were explored aiming at the identification of putative novel therapies for prostate and bladder cancer. The first part of this thesis (Chapter 2 and Chapter 3) describes the generationof preclinical, patient-derived model systems of prostate and bladder cancer. In Chapter 2, an overview is provided of the most commonly used patient-derived model systems for urological tumors, and a framework on how these patient derived tumor models can be employed to address preclinical and clinical unmet needs is presented. In Chapter 3, we developed and optimized the culture of ex vivo tumor tissue slices and employed this model to detect anti-tumor responses of chemotherapeutic agents Docetaxel and Gemicitabin. Subsequently in Chapters 4, 5 and 6, we describe the use of multiple preclinical translational models, including patient-derived tumor models. In Chapter 4 and 5 the translational potential of the approved antipsychotic drug penfluridol was determined in bladder and prostate cancer. In Chapter 6, the use of oncolytic reovirus jin-3 as putative novel therapeutic strategy for the treatment of prostate is investigated. Finally, in Chapter 7, we describe a novel preclinical screening strategy based on E-cadherin (re)induction and inhibition of invasion for the identification of a new class of small molecules for the treatment of aggressive epithelial cancers. Show less
Merbel, A.F. van de; Horst, G. van der; Mark, M.H. van der; Bots, S.T.F.; Wollenberg, D.J.M. van den; Ridder, C.M.A. de; ... ; Pluijm, G. van der 2021
Treatment of castration-resistant prostate cancer remains a challenging clinical problem. Despite the promising effects of immunotherapy in other solid cancers, prostate cancer has remained largely... Show moreTreatment of castration-resistant prostate cancer remains a challenging clinical problem. Despite the promising effects of immunotherapy in other solid cancers, prostate cancer has remained largely unresponsive. Oncolytic viruses represent a promising therapeutic avenue, as oncolytic virus treatment combines tumour cell lysis with activation of the immune system and mounting of effective anti-tumour responses. Mammalian Orthoreoviruses are non-pathogenic human viruses with a preference of lytic replication in human tumour cells. In this study, we evaluated the oncolytic efficacy of the bioselected oncolytic reovirus mutant jin-3 in multiple human prostate cancer models. The jin-3 reovirus displayed efficient infection, replication, and anti-cancer responses in 2D and 3D prostate cancer models, as well as in ex vivo cultured human tumour slices. In addition, the jin-3 reovirus markedly reduced the viability and growth of human cancer cell lines and patient-derived xenografts. The infection induced the expression of mediators of immunogenic cell death, interferon-stimulated genes, and inflammatory cytokines. Taken together, our data demonstrate that the reovirus mutant jin-3 displays tumour tropism, and induces potent oncolytic and immunomodulatory responses in human prostate cancer models. Therefore, jin-3 reovirus represents an attractive candidate for further development as oncolytic agent for treatment of patients with aggressive localised or advanced prostate cancer. Show less
Merbel, A.F. van de; Hooij, O. van; Horst, G. van der; Rijt-van de Westerlo, C.C.M. van; Mark, M.H. van der; Cheung, H.; ... ; Pluijm, G. van der 2021
Transformed epithelial cells can activate programs of epithelial plasticity and switch from a sessile, epithelial phenotype to a motile, mesenchymal phenotype. This process is linked to the... Show moreTransformed epithelial cells can activate programs of epithelial plasticity and switch from a sessile, epithelial phenotype to a motile, mesenchymal phenotype. This process is linked to the acquisition of an invasive phenotype and the formation of distant metastases. The development of compounds that block the acquisition of an invasive phenotype or revert the invasive mesenchymal phenotype into a more differentiated epithelial phenotype represent a promising anticancer strategy. In a high-throughput assay based on E-cadherin (re)induction and the inhibition of tumor cell invasion, 44,475 low molecular weight (LMW) compounds were screened. The screening resulted in the identification of candidate compounds from the PROAM02 class. Selected LMW compounds activated E-cadherin promoter activity and inhibited cancer cell invasion in multiple metastatic human cancer cell lines. The intraperitoneal administration of selected LMW compounds reduced the tumor burden in human prostate and breast cancer in vivo mouse models. Moreover, selected LMW compounds decreased the intra-bone growth of xenografted human prostate cancer cells. This study describes the identification of the PROAM02 class of small molecules that can be exploited to reduce cancer cell invasion and metastases. Further clinical evaluation of selected candidate inhibitors is warranted to address their safety, bioavailability and antitumor efficacy in the management of patients with aggressive cancers. Show less
Horst, G. van der; Merbel, A.F. van de; Ruigrok, E.; Mark, M.H. van der; Ploeg, E.; Appelman, L.; ... ; Zwarthoff, E.C. 2020
More effective therapy for patients with either muscle-invasive or high-risk non-muscle-invasive urothelial carcinoma of the bladder (UCB) is an unmet clinical need. For this, drug repositioning of... Show moreMore effective therapy for patients with either muscle-invasive or high-risk non-muscle-invasive urothelial carcinoma of the bladder (UCB) is an unmet clinical need. For this, drug repositioning of clinically approved drugs represents an interesting approach. By repurposing existing drugs, alternative anticancer therapies can be introduced in the clinic relatively fast, because the safety and dosing of these clinically approved pharmacological agents are generally well known. Cationic amphiphilic drugs (CADs) dose-dependently decreased the viability of a panel of human UCB linesin vitro. CADs induced lysosomal puncta formation, a hallmark of lysosomal leakage. Intravesical instillation of the CAD penfluridol in an orthotopic mouse xenograft model of human UCB resulted in significantly reduced intravesical tumor growth and metastatic progression. Furthermore, treatment of patient-derivedex vivocultured human UCB tissue caused significant partial or complete antitumor responses in 97% of the explanted tumor tissues. In conclusion, penfluridol represents a promising treatment option for bladder cancer patients and warrants further clinical evaluation. Show less
Urological malignancies, including prostate and bladder carcinoma, represent a major clinical problem due to the frequent occurrence of therapy resistance and the formation of incurable distant... Show moreUrological malignancies, including prostate and bladder carcinoma, represent a major clinical problem due to the frequent occurrence of therapy resistance and the formation of incurable distant metastases. As a result, there is an urgent need for versatile and predictive disease models for the assessment of the individualized drug response in urological malignancies. Compound testing on ex vivo cultured patient-derived tumor tissues could represent a promising approach. In this study, we have optimized an ex vivo culture system of explanted human prostate and bladder tumors derived from clinical specimens and human cancer cell lines xenografted in mice. The explanted and cultured tumor slices remained viable and tissue architecture could be maintained for up to 10 days of culture. Treatment of ex vivo cultured human prostate and bladder cancer tissues with docetaxel and gemcitabine, respectively, resulted in a dose-dependent anti-tumor response. The dose-dependent decrease in tumor cells upon administration of the chemotherapeutic agents was preceded by an induction of apoptosis. The implementation and optimization of the tissue slice technology may facilitate the assessment of anti-tumor efficacies of existing and candidate pharmacological agents in the complex multicellular neoplastic tissues from prostate and bladder cancer patients. Our model represents a versatile "near-patient" tool to determine tumor-targeted and/or stroma-mediated anti-neoplastic responses, thus contributing to the field of personalized therapeutics. Show less
Merbel, A.F. van de; Horst, G. van der; Mark, M.H. van der; Uhm, J.I.M. van; Gennep, E.J. van; Kloen, P.; ... ; Pluijm, G. van der 2018
Urological malignancies, including prostate and bladder carcinoma, represent a major clinical problem due to the frequent occurrence of therapy resistance and the formation of incurable distant... Show moreUrological malignancies, including prostate and bladder carcinoma, represent a major clinical problem due to the frequent occurrence of therapy resistance and the formation of incurable distant metastases. As a result, there is an urgent need for versatile and predictive disease models for the assessment of the individualized drug response in urological malignancies. Compound testing on ex vivo cultured patient-derived tumor tissues could represent a promising approach. In this study, we have optimized an ex vivo culture system of explanted human prostate and bladder tumors derived from clinical specimens and human cancer cell lines xenografted in mice. The explanted and cultured tumor slices remained viable and tissue architecture could be maintained for up to 10 days of culture. Treatment of ex vivo cultured human prostate and bladder cancer tissues with docetaxel and gemcitabine, respectively, resulted in a dose-dependent anti-tumor response. The dose-dependent decrease in tumor cells upon administration of the chemotherapeutic agents was preceded by an induction of apoptosis. The implementation and optimization of the tissue slice technology may facilitate the assessment of anti-tumor efficacies of existing and candidate pharmacological agents in the complex multicellular neoplastic tissues from prostate and bladder cancer patients. Our model represents a versatile “near-patient” tool to determine tumor-targeted and/or stroma-mediated anti-neoplastic responses, thus contributing to the field of personalized therapeutics. Show less
Altered microRNA (miRNA; miR) expression is associated with tumor formation and progression of various solid cancers. A major challenge in miRNA expression profiling of bulk tumors is represented... Show moreAltered microRNA (miRNA; miR) expression is associated with tumor formation and progression of various solid cancers. A major challenge in miRNA expression profiling of bulk tumors is represented by the heterogeneity of the subpopulations of cells that constitute the organ, as well as the tumor tissue. Here, we analyzed the expression of miRNAs in a subpopulation of epithelial stem/progenitor-like cells in human prostate cancer [prostate cancer stem cell (PCSC)] and compared their expression profile to more differentiated cancer cells. In both cell lines and clinical prostate cancer specimens, we identified that miR-25 expression in PCSCs was low/absent and steadily increased during their differentiation into cells with a luminal epithelial phenotype. Functional studies revealed that overexpression of miR-25 in prostate cancer cell lines and selected subpopulation of highly metastatic and tumorigenic cells (ALDH(high)) strongly affected the invasive cytoskeleton, causing reduced migration in vitro and metastasis via attenuation of extravasation in vivo. Here, we show, for the first time, that miR-25 can act as a tumor suppressor in highly metastatic PCSCs by direct functional interaction with the 3'-untranslated regions of proinvasive αv- and α6-integrins. Taken together, our observations suggest that miR-25 is a key regulator of invasiveness in human prostate cancer through its direct interactions with αv- and α6-integrin expression. Show less
Zoni, E.; Merbel, A.F. van de; Horst, G. van der; Rane, J.; Visakorpi, T.; Snaar, E.B.; ... ; Pluijm, G. van der 2014
