Vanessa Rausch

Sulforaphane targets pancreatic tumour-initiating cells by NF-κB-induced antiapoptotic signalling

Background and aims: Emerging evidence suggests that highly treatment-resistant tumour-initiating cells (TICs) play a central role in the pathogenesis of pancreatic cancer. Tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) is considered to be a novel anticancer agent; however, recent studies have shown that many pancreatic cancer cells are resistant to apoptosis induction by TRAIL due to TRAIL-activated nuclear factor-κB (NF-κB) signalling. Several chemopreventive agents are able to inhibit NF-κB, and favourable results have been obtained—for example, for the broccoli compound sulforaphane—in preventing metastasis in clinical studies. The aim of the study was to identify TICs in pancreatic carcinoma for analysis of resistance mechanisms and for definition of sensitising agents. Methods: TICs were defined by expression patterns of a CD44+/CD24−, CD44+/CD24+ or CD44+/CD133+ phenotype and correlation to growth in immunodeficient mice, differentiation grade, clonogenic growth, sphere formation, aldehyde dehydrogenase (ALDH) activity and therapy resistance. Results: Mechanistically, specific binding of transcriptionally active cRel-containing NF-κB complexes in TICs was observed. Sulforaphane prevented NF-κB binding, downregulated apoptosis inhibitors and induced apoptosis, together with prevention of clonogenicity. Gemcitabine, the chemopreventive agents resveratrol and wogonin, and the death ligand TRAIL were less effective. In a xenograft model, sulforaphane strongly blocked tumour growth and angiogenesis, while combination with TRAIL had an additive effect without obvious cytotoxicity in normal cells. Freshly isolated patient tumour cells expressing markers for TICs could be sensitised by sulforaphane for TRAIL-induced cytotoxity. Conclusion: The data provide new insights into resistance mechanisms of TICs and suggest the combination of sulforaphane with TRAIL as a promising strategy for targeting of pancreatic TICs.

Synergistic Activity of Sorafenib and Sulforaphane Abolishes Pancreatic Cancer Stem Cell Characteristics

Recent evidence suggests that pancreatic cancer and other solid tumors contain a subset of tumorigenic cells capable of extensive self-renewal that contribute to metastasis and treatment resistance. Sorafenib (SO) is a promising new multikinase inhibitor for treatment of advanced kidney and liver cancers. We report here targeting of pancreatic cancer stem cells (CSC) by SO and the development of a strategy to enhance this effect. Although SO administration diminished clonogenicity, spheroid formation, aldehyde dehydrogenase 1 (ALDH1) activity, growth on immunodeficient mice, proliferation, and angiogenesis and induced apoptosis, we observed SO-induced activation of NF-kappaB associated with survival and regrowth of spheroids. For enhanced elimination of CSC characteristics by SO, we cotreated cells with sulforaphane (SF). This broccoli isothiocyanate was recently described to eliminate pancreatic CSCs by downregulation of NF-kappaB activity without inducing toxic side effects. On combination treatment, SF completely eradicated SO-induced NF-kappaB binding, which was associated with abrogated clonogenicity, spheroid formation, ALDH1 activity, migratory capacity, and induction of apoptosis. In vivo, combination therapy reduced the tumor size in a synergistic manner. This was due to induction of apoptosis, inhibition of proliferation and angiogenesis, and downregulation of SO-induced expression of proteins involved in epithelial-mesenchymal transition. Our data suggest that SF may be suited to increase targeting of CSCs by SO.

Sulforaphane Increases Drug-mediated Cytotoxicity Toward Cancer Stem-like Cells of Pancreas and Prostate

Despite intense efforts to develop treatments against pancreatic cancer, agents that cure this highly resistant and metastasizing disease are not available. Considerable attention has focused on broccoli compound sulforaphane (SF), which is suggested as combination therapy for targeting of pancreatic cancer stem cells (CSCs). However, there are concerns that antioxidative properties of SF may interfere with cytotoxic drugs-as suggested, e.g., for vitamins. Therefore we investigated a combination therapy using established pancreatic CSCs. Although cisplatin (CIS), gemcitabine (GEM), doxorubicin, 5-flurouracil, or SF effectively induced apoptosis and prevented viability, combination of a drug with SF increased toxicity. Similarly, SF potentiated the drug effect in established prostate CSCs revealing that SF enhances drug cytotoxicity also in other tumor entities. Most importantly, combined treatment intensified inhibition of clonogenicity and spheroid formation and aldehyde dehydrogenase 1 (ALDH1) activity along with Notch-1 and c-Rel expression indicating that CSC characteristics are targeted. In vivo, combination treatment was most effective and totally abolished growth of CSC xenografts and tumor-initiating potential. No pronounced side effects were observed in normal cells or mice. Our data suggest that SF increases the effectiveness of various cytotoxic drugs against CSCs without inducing additional toxicity in mice.

Autophagy mediates survival of pancreatic tumour‐initiating cells in a hypoxic microenvironment

Involvement of dysregulated autophagy in cancer growth and progression has been shown in different tumour entities, including pancreatic ductal adenocarcinoma (PDA). PDA is an extremely aggressive tumour characterized by a small population of highly therapy‐resistant cancer stem cells (CSCs) capable of self‐renewal and migration. We examined whether autophagy might be involved in the survival of CSCs despite nutrition and oxygen deprivation typical for the hypoxic tumour microenvironment of PDA. Immunohistochemistry revealed that markers for hypoxia, CSCs and autophagy are co‐expressed in patient‐derived tissue of PDA. Hypoxia starvation (H/S) enhanced clonogenic survival and migration of established pancreatic cancer cells with stem‐like properties (CSC

Non-invasive diagnosis of alcoholic liver disease

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Targeting of pancreatic and prostate cancer stem cell characteristics by Crambe crambe marine sponge extract.

, while pancreatic tumour cells with fewer stem cell markers (CSC

The Role of Iron in Alcohol-Mediated Hepatocarcinogenesis

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Primary liver injury and delayed resolution of liver stiffness after alcohol detoxification in heavy drinkers with the PNPLA3 variant I148M

did not survive these conditions. Electron microscopy revealed more advanced autophagic vesicles in CSC

Arterial pressure suffices to increase liver stiffness

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Caspase‐cleaved keratin‐18 fragments increase during alcohol withdrawal and predict liver‐related death in patients with alcoholic liver disease

cells, which exhibited higher expression of autophagy‐related genes under normoxic conditions and relative to CSC