Jury Gladkich

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.

Hypoxia induces EMT in low and highly aggressive pancreatic tumor cells but only cells with cancer stem cell characteristics acquire pronounced migratory potential.

Tumor hypoxia induces epithelial-mesenchymal transition (EMT), which induces invasion and metastasis, and is linked to cancer stem cells (CSCs). Whether EMT generates CSCs de novo, enhances migration of existing CSCs or both is unclear. We examined patient tissue of pancreatic ductal adenocarcinoma (PDA) along with carcinomas of breast, lung, kidney, prostate and ovary. For in vitro studies, five established PDA cell lines classified as less (CSClow) and highly aggressive CSC-like cells (CSChigh) were examined by single and double immunofluorescence microscopy, wound-, transwell-, and time-lapse microscopy. HIF-1α and Slug, as well as HIF-2α and CD133 were co-expressed pointing to a putative co-existence of hypoxia, EMT and CSCs in vivo. CSChigh cells exhibited high basal expression of the mesenchymal Vimentin protein but low or absent expression of the epithelial marker E-cadherin, with the opposite result in CSClow cells. Hypoxia triggered altering of cell morphology from an epithelial to a mesenchymal phenotype, which was more pronounced in CSChigh cells. Concomitantly, E-cadherin expression was reduced and expression of Vimentin, Slug, Twist2 and Zeb1 enhanced. While hypoxia caused migration in all cell lines, velocity along with the percentage of migrating, polarized and pseudopodia-forming cells was significantly higher in CSChigh cells. These data indicate that hypoxia-induced EMT occurs in PDA and several other tumor entities. However although hypoxia-induced EMT signaling occurs in all tumor cell populations, only the stem-like cells acquire high migratory potential and thus may be responsible for invasion and metastasis.

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

The novel c-Met inhibitor cabozantinib overcomes gemcitabine resistance and stem cell signaling in pancreatic cancer

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Triptolide reverses hypoxia-induced epithelial–mesenchymal transition and stem-like features in pancreatic cancer by NF-κB downregulation

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

Sulforaphane and TRAIL induce a synergistic elimination of advanced prostate cancer stem-like cells

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New gene-immunotherapy combining TRAIL-lymphocytes and EpCAMxCD3 bispecific antibody for tumor targeting

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

Up-regulation of microRNA Let-7c by quercetin inhibits pancreatic cancer progression by activation of Numbl.

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Enrichment of c-Met + tumorigenic stromal cells of giant cell tumor of bone and targeting by cabozantinib

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