Monanchocidin A (MonA) is a novel alkaloid recently isolated from the marine sponge Monanchora pulchra. The compound reveals cytotoxic activity in genitourinary cancers including cisplatin-sensitive ...and -resistant germ cell tumor (GCT) cell lines, hormone-sensitive and castration-resistant prostate carcinoma cell lines and different bladder carcinoma cell lines. In contrast, non-malignant cells were significantly less sensitive. MonA is highly synergistic with cisplatin in GCT cells. Induction of autophagy at lower and lysosomal membrane permeabilization (LMP) at higher concentrations were identified as the dominating modes of action. Cytotoxicity and protein degradation could be inhibited by 3-methyladenine, an inhibitor of autophagy. LMP was confirmed by loss of acridine orange staining of lysosoms and by release of cathepsin B. In conclusion, MonA exerts cytotoxic activity by mechanisms different from "classical" apoptosis, and could be a promising new compound to overcome resistance to standard therapies in genitourinary malignancies.
For patients with refractory or relapsed Burkitt lymphoma (BL), no standard therapy is available for second-line treatment to date. Nonfunctional caspases-dependent apoptosis pathways, inactivating ...p53 mutations and pro-survival autophagy prevent activity of conventional chemotherapy. Thus, new drugs bypassing these mechanisms of resistance are required. Here, we investigated the efficacy of the marine natural compound frondoside A (FrA) in eight BL cell lines. FrA revealed cytotoxic effects in all cell lines tested including the multiresistant CA46 cells. Remarkably, FrA induced caspases- and p53-independent apoptosis, which was characterized by decreased expression of antiapoptotic survivin and Bcl-2, mitochondria targeting (release of cytochrome C, HtrA2/Omi and the apoptosis-inducing factor (AIF), and altered production of ROS) and translocation of AIF to the nuclei. In addition, signs of inhibition of pro-survival autophagy were observed. Thus, FrA is a promising candidate for the treatment of refractory or relapsed BL revealing resistances to standard therapies.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Background
Cisplatin-based chemotherapy is highly effective in metastasized germ cell tumours (GCT). However, 10–30 % of patients develop resistance to cisplatin, requiring salvage therapy. We ...investigated the in vitro activity of paclitaxel and the novel taxane cabazitaxel in cisplatin-sensitive and -resistant GCT cell lines.
Methods
In vitro activity of paclitaxel and cabazitaxel was determined by proliferation assays, and mode of action of cabazitaxel was assessed by western blotting and two screening approaches, i.e. whole proteome analysis and a human apoptosis array.
Results
Activity of paclitaxel and cabazitaxel was not affected by cisplatin resistance, suggesting that there is no cross-resistance between these agents in vitro. Cabazitaxel treatment showed a strong inhibitory effect on colony formation capacity. Cabazitaxel induced classical apoptosis in all cell lines, reflected by cleavage of PARP and caspase 3, without inducing specific changes in the cell cycle distribution. Using the proteomic and human apoptosis array screening approaches, differential regulation of several proteins, including members of the bcl-2 family, was found, giving first insights into the mode of action of cabazitaxel in GCT.
Conclusion
Cabazitaxel shows promising in vitro activity in GCT cells, independent of levels of cisplatin resistance.
Despite recent advances in the treatment of metastatic castration-resistant prostate cancer (CRPC), treatment is inevitably hampered by the development of drug resistance. Thus, new drugs are ...urgently needed. We investigated the efficacy, toxicity, and mechanism of action of the marine triterpene glycoside cucumarioside A
-2 (CA
-2) using an in vitro CRPC model. CA
-2 induced a G
/M-phase cell cycle arrest in human prostate cancer PC-3 cells and caspase-dependent apoptosis executed via an intrinsic pathway. Additionally, the drug inhibited the formation and growth of CRPC cell colonies at low micromolar concentrations. A global proteome analysis performed using the 2D-PAGE technique, followed by MALDI-MS and bioinformatical evaluation, revealed alterations in the proteins involved in cellular processes such as metastatic potential, invasion, and apoptosis. Among others, the regulation of keratin 81, CrkII, IL-1β, and cathepsin B could be identified by our proteomics approach. The effects were validated on the protein level by a 2D Western blotting analysis. Our results demonstrate the promising anticancer activity of CA
-2 in a prostate cancer model and provide insights on the underlying mode of action.
Germ cell tumors (GCTs) are the most frequent malignancy in male patients between 15 and 45 years of age. Cisplatin-based chemotherapy shows excellent cure rates, but patients with ...cisplatin-resistant GCTs have a poor prognosis. Nintedanib (BIBF 1120, Vargatef) inhibits the receptor classes vascular endothelial growth factor receptor, platelet derived growth factor receptor, and fibroblast growth factor receptor, and has shown activity against many tumors, as well as in idiopathic lung fibrosis and bleomycin-induced lung injury. Here, we investigated the antineoplastic and antiangiogenic properties of nintedanib in cisplatin-resistant and cisplatin-sensitive GCT cells, both alone and in combination with classical cytotoxic agents such as cisplatin, etoposide, and bleomycin. The half-maximal inhibitory concentration (IC50) of nintedanib was 4.5±0.43 μmol/l, 3.1±0.45 μmol/l, and 3.6±0.33 μmol/l in cisplatin-sensitive NTERA2, 2102Ep, and NCCIT cells, whereas the IC50 doses of the cisplatin-resistant counterparts were 6.6±0.37 μmol/l (NTERA2-R), 4.5±0.83 μmol/l (2102Ep-R), and 6.1±0.41 μmol/l (NCCIT-R), respectively. Single treatment with nintedanib induced apoptosis and resulted in a sustained reduction in the capacity of colony formation in both cisplatin-sensitive and cisplatin-resistant GCT cells. Cell cycle analysis showed that nintedanib induced a strong G0/G1-phase arrest in all investigated cell lines. Combination treatment with cisplatin did not result in additive, synergistic, or antagonistic effects. The in-vivo activity was studied using the chorioallantoic membrane assay and indicated the antiangiogenic potency of nintedanib with markedly reduced microvessel density. Topical treatment of inoculated tumor plaques resulted in a significant reduction of the tumor size. This indicates that nintedanib might be a promising substance in the treatment of GCT.
Rhizochalinin (Rhiz) is a novel marine natural sphingolipid‐like compound, which shows promising in vitro and in vivo activity in human castration‐resistant prostate cancer. In the present study, a ...global proteome screening approach was applied to investigate molecular targets and biological processes affected by Rhiz in castration‐resistant prostate cancer. Bioinformatical analysis of the data predicted an antimigratory effect of Rhiz on cancer cells. Validation of proteins involved in the cancer‐associated processes, including cell migration and invasion, revealed downregulation of specific isoforms of stathmin and LASP1, as well as upregulation of Grp75, keratin 81, and precursor IL‐1β by Rhiz. Functional analyses confirmed an antimigratory effect of Rhiz in PC‐3 cells. Additionally, predicted ERK1/2 activation was confirmed by Western blotting analysis, and revealed prosurvival effects in Rhiz‐treated prostate cancer cells indicating a potential mechanism of resistance. A combination of Rhiz with MEK/ERK inhibitors PD98059 (non‐ATP competitive MEK1 inhibitor) and FR180204 (ATP‐competitive ERK1/2 inhibitor) resulted in synergistic effects. This work provides further insights into the molecular mechanisms underlying Rhiz bioactivity. Furthermore, our research is exemplary for the ability of proteomics to predict drug targets and mode of action of natural anticancer agents.
Development of resistance to standard therapies complicates treatment of advanced prostate cancer. Alternative splicing variants of the androgen receptor (AR), e.g. AR-V7 can mediate resistance to ...AR-targeting substances abiraterone and enzalutamide. Semi-synthetic marine natural compound rhizochalinin decreases the expression of AR-V7 in human castration-resistant prostate cancer cells and thus resensitizes cells to enzalutamide. In the current study, we modified the structure of rhizochalin in order to determine structure-activity relationships (SAR) and optimize anticancer properties. Thus, we synthesized new 18-hydroxy- and 18-aminorhizochalins and its aglycones. All compounds exhibited anticancer properties in human castration-resistant prostate cancer cells, induced apoptosis and G2/M cell cycle arrest, and were capable of autophagy inhibition. SAR analysis showed an increase of pro-apoptotic activity in the row 18-amino < 18-hydroxy < 18-keto derivatives. In general, aglycones were more cytotoxic compared to glycosides. The sugar elimination was critical for the ability to suppress AR-signaling. Rhizochalinin (2) and 18-hydroxyrhizochalinin (4) were identified as the most promising derivatives and are promoted for further development.
Monanchocidin A (MonA) is a novel marine alkaloid with promising anti‐cancer properties. We recently demonstrated its high efficacy in human urogenital cancers including germ cell tumors. Here, we ...applied a global proteome screening approach to investigate molecular targets and biological processes affected by MonA in the human cisplatin‐resistant germ cell cancer cell line NCCIT‐R. Bioinformatical analysis of the proteomics data predicted an effect of MonA on cancer cell migration. Thus, proteins known to be involved in cancer cell migration and invasion were chosen for further validation. The protein alterations identified by proteomics resulted from both, regulation of the total protein expression and post‐transcriptional modifications. Among others, regulation of an isoform of vimentin, up‐regulation of multiple apolipoprotein E isoforms, and inhibition of hypusination of eukaryotic translation initiation factor 5A‐1 were found upon treatment with MonA. Further functional analyses were performed and revealed decreased cell migration and colony formation of cancer cells treated with MonA at non‐cytotoxic and non‐antiproliferative concentrations. This work provides further insights into the molecular mechanisms behind MonA bioactivity. Furthermore, our research is exemplary for the ability of proteomics to predict drug targets and mode of action of natural anti‐cancer agents.
Tumors may develop resistance to specific angiogenic inhibitors via activation of alternative pathways. Therefore, multiple angiogenic pathways should be targeted to achieve significant angiogenic ...blockade. In this study we investigated the effects of a combined application of the angiogenic inhibitors endostatin and tumstatin in a model of human glioblastoma multiforme.
Inhibitors released by stably transfected porcine aortic endothelial cells (PAE) showed anti-angiogenic activity in proliferation and wound-healing assays with endothelial cells (EC). Interestingly, combination of endostatin and tumstatin (ES + Tum) also reduced proliferation of glioma cells and additionally induced morphological changes and apoptosis in vitro. Microencapsulated PAE-cells producing these inhibitors were applied for local therapy in a subcutaneous glioblastoma model. When endostatin or tumstatin were applied separately, in vivo tumor growth was inhibited by 58% and 50%, respectively. Combined application of ES + Tum, in comparison, resulted in a significantly more pronounced inhibition of tumor growth (83%). cDNA microarrays of tumors treated with ES + Tum revealed an up-regulation of prolactin receptor (PRLR). ES + Tum-induced up-regulation of PRLR in glioma cells was also found in in vitro. Moreover, exogenous PRLR overexpression in vitro led to up-regulation of its ligand prolactin and increased proliferation suggesting a functional autocrine growth loop in these cells.
Our data indicate that integrin-targeting factors endostatin and tumstatin act additively by inhibiting glioblastoma growth via reduction of vessel density but also directly by affecting proliferation and viability of tumor cells. Treatment with the ES + Tum-combination activates the PRLR pro-proliferative pathway in glioblastoma. Future work will show whether the prolactin signaling pathway represents an additional target to improve therapeutic strategies in this entity.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
PDF
