Publications by authors named "Tobias Busenbender"

Background: Advanced stages of prostate cancer (PCa), in particular metastatic castration-resistant prostate cancer (mCRPC), are associated with significant morbidity and mortality. The androgen receptor (AR) signaling pathway is a cornerstone of therapeutic intervention, but resistance mechanisms and disease progression demand increasingly complex treatment strategies.

Methods: This narrative review is based on expert consensus, supported by a literature search in PubMed (MEDLINE) and the abstract databases of ASCO, ASCO GU and ESMO.

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The Warburg effect is a shift from oxidative phosphorylation to anaerobic glycolysis, accompanied by an enormous increase in glucose uptake into cancer cells. We have utilized this effect to design a new group of targeted 1,4-naphthoquinone-glucose derivatives conjugated with a novel thiomethylene linker that are cytotoxic to prostate cancer cells. Compound PeS-9 revealed the highest efficacy and selectivity, which was conditioned by a GLUT-1-mediated uptake.

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Purpose: New biomarkers for the detection and monitoring of aggressive variant prostate cancer (AVPC) including therapy-induced neuroendocrine prostate cancer (NEPC) are urgently needed, as measuring prostate-specific antigen (PSA) is not reliable in androgen-indifferent diseases. Molecular analysis of circulating tumor cells (CTC) enables repeated analysis for monitoring and allows to capture the heterogeneity of the disease.

Experimental Design: 102 blood samples from 76 metastatic prostate cancer (mPC) patients, including 37 samples from histologically proven NEPC, were collected and CTCs were enriched using label-dependent and label-independent methods.

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Article Synopsis
  • Fascaplysin is a red pigment from the marine sponge Fascaplysinopsis sp. with anticancer properties, and recent analysis links its cytotoxicity to its interaction with DNA.
  • Two derivatives, 6- and 7-tert-butylfascaplysins, were synthesized and showed strong toxicity against drug-resistant prostate cancer cells without improved cancer cell selectivity.
  • The study suggests a complex relationship between fascaplysin derivatives' structure, their mechanisms of action, and proposes further research on combination therapies targeting the ATR/CHK1 axis in cancers that are sensitive to DNA damage.
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Rhizochalinin (Rhiz) is a recently discovered cytotoxic sphingolipid synthesized from the marine natural compound rhizochalin. Previously, Rhiz demonstrated high in vitro and in vivo efficacy in various cancer models. Here, we report Rhiz to be highly active in human glioblastoma cell lines as well as in patient-derived glioma-stem like neurosphere models.

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Marine fungi serve as a valuable source for new bioactive molecules bearing various biological activities. In this study, we report on the isolation of a new indole diketopiperazine alkaloid deoxy-14,15-dehydroisoaustamide () from the marine-derived fungus KMM 4689 associated with a soft coral. The structure of this metabolite, including its absolute configuration, was determined by HR-MS, 1D and 2D NMR as well as CD data.

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N-methylpretrichodermamide B (NB) is a biologically active epidithiodiketopiperazine isolated from several strains of the algae-derived fungus sp. Recently, we reported the first data on its activity in human cancer cells lines in vitro. Here, we investigated the activity, selectivity, and mechanism of action of NB in human prostate cancer cell lines, including drug-resistant subtypes.

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Article Synopsis
  • * Two specific compounds showed high effectiveness against human prostate cancer cells, including those resistant to hormonal therapy and docetaxel, and worked by causing cell death through a process called caspase-dependent apoptosis.
  • * These compounds not only suppressed the androgen receptor signaling but also inhibited drug resistance mechanisms, indicating their potential for use in combination with standard chemotherapy treatments like docetaxel.
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Marine alkaloid fascaplysin and its derivatives are known to exhibit promising anticancer properties in vitro and in vivo. However, toxicity of these molecules to non-cancer cells was identified as a main limitation for their clinical use. Here, for the very first time, we synthesized a library of fascaplysin derivatives covering all possible substituent introduction sites, i.

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Development of resistance to currently available standard therapies in advanced prostate cancer (PCa) emphasizes the need for novel therapeutic options. Here, we report the synthesis of new hybrid molecules consisting of 2-chloroethylthio and 1,4-naphthoquinone pharmacophores and describe their activity in PCa. In screening analyses, the introduction of one 2-chloroethylthio group improved the anticancer properties of 1,4-naphthoquinones, whereas the introduction of a second 2-chloroethylthio moiety rather decreased activity.

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Article Synopsis
  • The marine alkaloid 3,10-dibromofascaplysin (DBF) shows potential anticancer activity against human prostate cancer cells, even those resistant to standard therapies.
  • DBF primarily targets JNK1/2 pathways without activating p38 and ERK1/2 MAPKs, and its effectiveness is enhanced when combined with PARP-inhibitor olaparib and platinum-based drugs.
  • Additionally, DBF can inhibit androgen receptor signaling and resensitize resistant prostate cancer cells to enzalutamide, suggesting it could be a valuable new treatment option for advanced prostate cancer.
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Monanchoxymycalin C (MomC) is a new marine pentacyclic guanidine alkaloid, recently isolated from marine sponge Monanchora pulchra by us. Here, anticancer activity and mechanism of action was investigated for the first time using a human prostate cancer (PCa) model. MomC was active in all PCa cell lines at low micromolar concentrations and induced an unusual caspase-independent, non-apoptotic cell death.

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New bicyclic guanidine alkaloid, urupocidin C (Ur-C) along with the previously known urupocidin A (Ur-A) were isolated from the rare deep-sea marine sponge Monanchora pulchra, harvested in Northwestern Pacific waters. The unique structure of Ur-C was elucidated using 1D and 2D NMR spectroscopy as well as mass spectra. We discovered a promising selectivity of both alkaloids for human prostate cancer (PCa) cells, including highly drug-resistant lines, compared to non-malignant cells.

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Article Synopsis
  • The Warburg effect describes how tumor cells consume high levels of sugar due to their reliance on glycolysis, even in the presence of oxygen.
  • Researchers have developed new sugar-based compounds, specifically designed to target this effect, which show promise in selectively killing prostate cancer cells, even those resistant to traditional drugs.
  • The mechanism of action involves disrupting mitochondrial function, leading to the activation of processes that induce apoptosis, paving the way for potential clinical development of these compounds.
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From a root bark of Turch we isolated two new (7 and 8) and six previously known compounds (1-6) belonging to the group of prenylated polyphenols. Their structures were elucidated using mass spectrometry, nuclear magnetic resonance and circular dichroism spectroscopy. These natural compounds selectively inhibited human drug-resistant prostate cancer in vitro.

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Treatment of castration-resistant prostate cancer (CRPC) remains challenging due to the development of drug resistance. The Warburg effect describes the ability of cancer cells to consume larger amounts of glucose compared to normal tissues. We identified derivatives of natural 1,4-naphthoquinones to be active in CRPC and further synthetically modified them via glucose conjugation to increase selectivity by Warburg effect targeting.

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