技术资料

Cancer initiation and progression have been attributed to newly discovered subpopulations of self-renewing,highly tumorigenic,drug-resistant tumor cells termed cancer stem cells. Recently,we and others reported a new phenotypic plasticity wherein highly tumorigenic,drug-resistant cell populations could arise not only from pre-existing cancer stem-like populations but also from cancer cells lacking these properties. In the current study,we hypothesized that this newfound phenotypic plasticity may be mediated by PI3K/Akt and Wnt/β-catenin signaling,pathways previously implicated in carcinogenesis,pluripotency and drug resistance. Using GFP expression,Hoechst dye exclusion and fluorescence activated cell sorting (FACS) of cancer cell lines,we identified and tracked cancer stem-like side populations (SP) of cancer cells characterized by high tumorigenicity and drug resistance. We found that pharmacological inhibition or genetic depletion of PI3K and AKT markedly reduced the spontaneous conversion of nonside population (NSP) cells into cancer stem-like SP cells,whereas PI3K/Akt activation conversely enhanced NSP to SP conversion. PI3K/AKT signaling was mediated through downstream phosphorylation of GSK3β,which led to activation and accumulation of β-catenin. Accordingly,pharmacological or genetic perturbation of GSK3β or β-catenin dramatically impacted conversion of NSP to SP. Further downstream,β-catenin's effects on NSP-SP equilibrium were dependent upon its interaction with CBP,a KAT3 family coactivator. These studies provide a mechanistic model wherein PI3K/Akt/β-catenin/CBP signaling mediates phenotypic plasticity in and out of a drug-resistant,highly tumorigenic state. Therefore,targeting this pathway has unique potential for overcoming the therapy resistance and disease progression attributed to the cancer stem-like phenotype. View Publication

Tumor cells at the tumor margin lose epithelial properties and acquire features of mesenchymal cells,a process called epithelial-to-mesenchymal transition (EMT). Recently,features of EMT were shown to be linked to cells with tumor-founding capability,so-called cancer stem cells (CSCs). Inducers of the EMT include several transcription factors,such as Snail (SNAI1) and Slug (SNAI2),as well as the secreted transforming growth factor (TGFß). In the present study,we found that EMT induction in MCF10A cells by stably expressing SNAI1 contributed to drug resistance and acquisition of stem/progenitor-like character as shown by increased cell population for surface marker CD44(+)/CD24(-) and mammosphere forming capacity. Using a microarray approach,we demonstrate that SNAI1 overexpression results in a dramatic change in signaling pathways involved in the regulation of cell death and stem cell maintenance. We showed that NF-$$B/MAPK signaling pathways are highly activated in MCF10A-SNAI1 cells by IL1ß stimulation,leading to the robust induction in IL6 and IL8. Furthermore,MCF10A-SNAI1 cells showed enhanced TCF/ß-catenin activity responding to the exogenous Wnt3a treatment. However,EMT-induced stem/progenitor cell activation process is tightly regulated in non-transformed MCF10A cells,as WNT5A and TGFB2 are strongly upregulated in MCF10A-SNAI1 cells antagonizing canonical Wnt pathway. In summary,our data provide new molecular findings how EMT contributes to the enhanced chemoresistance and the acquisition of stem/progenitor-like character by regulating signaling pathways. View Publication

In cancer microenvironment,aberrant glycosylation events of ECM proteins and cell surface receptors occur. We developed a protocol to generate 3D bioprinted models of colorectal cancer (CRC) crosslinking hyaluronic acid and gelatin functionalized with three signalling glycans characterized in CRC,3'-Sialylgalactose,6'-Sialylgalactose and 2'-Fucosylgalactose. The crosslinking,performed exploiting azide functionalized gelatin and hyaluronic acid and 4arm-PEG-dibenzocyclooctyne,resulted in biocompatible hydrogels that were 3D bioprinted with commercial CRC cells HT-29 and patient derived CRC tumoroids. The glycosylated hydrogels showed good 3D printability,biocompatibility and stability over the time. SEM and synchrotron radiation SAXS/WAXS analysis revealed the influence of glycosylation in the construct morphology,whereas MALDI-MS imaging showed that protein profiles of tumoroid cells vary with glycosylation,indicating that sialylation and fucosylation of ECM proteins induce diverse alterations to the proteome of the tumoroid and surrounding cells. View Publication