Pancreatic ductal adenocarcinoma is a particularly challenging malignancy characterized by poor responsiveness to conventional chemotherapy. Although this tumor frequently overexpresses or possesses constitutively activated variants of IGF-IR and EGFR/Her-2, clinical trials using inhibitors of these receptors have failed. ErbB receptors have been proposed as one mechanism involved in the resistance to IGF-IR inhibitors. Therefore, combined treatment with inhibitors of both IGF-IR and ErbB receptors would appear to be a good strategy for overcoming the emergence of resistance. Sensitivity of cells to NVP-AEW541 and lapatinib in single or combination treatment was assessed by MTT or WST-8 assays in a panel of human pancreatic cancer cell lines and cancer stem cells. Tumorspheres enriched in cancer stem cells were obtained from cultures growing in non-adherent cell plates. The effects on cell signalling pathways were analyzed by Western blot. We found that combined treatment with the IGF-IR and EGFR/Her-2 inhibitors NVP-AEW541 and lapatinib, respectively, synergistically inhibited pancreatic cancer cell growth. Analysis at molecular level argued in favor of cross-talk between IGF-IR and ErbBs pathways at IRS-1 level and indicated that the synergistic effect is associated with the total abolishment of Akt, Erk and IRS-1 phosphorylation. Moreover, these inhibitors acted synergistically in tumorsphere cultures to eliminate cancer stem cells, in contrast to their resistance to gemcitabine. Taken together, these data indicate that simultaneous blockade of IGF-IR and EGFR/Her-2 using NVP-AEW541 and lapatinib may overcome resistance in pancreatic cancer. Thus, the synergy observed with this combined treatment indicates that it may be possible to maximize patient benefit with the appropriate combination of currently known anticancer agents.

Pancreatic tumors contain cancer stem cells highly resistant to chemotherapy. The identification of therapies that can eliminate this population of cells might provide with more effective treatments. In the current work we evaluated the potential of oncolytic adenoviruses to act against pancreatic cancer stem cells (PCSC). PCSC from two patient-derived xenograft models were isolated from orthotopic pancreatic tumors treated with saline, or with the chemotherapeutic agent gemcitabine. An enrichment in the number of PCSC expressing the cell surface marker CD133 and a marked enhancement on tumorsphere formation was observed in gemcitabine treated tumors. No significant increase in the CD44, CD24, and epithelial-specific antigen (ESA) positive cells was observed. Neoplastic sphere-forming cells were susceptible to adenoviral infection and exposure to oncolytic adenoviruses resulted in elevated cytotoxicity with both Adwt and the tumor specific AduPARE1A adenovirus. In vivo, intravenous administration of a single dose of AduPARE1A in human-derived pancreatic xenografts led to a remarkable anti-tumor effect. In contrast to gemcitabine AduPARE1A treatment did not result in PCSC enrichment. No enrichment on tumorspheres neither on the CD133(+) population was detected. Therefore our data provide evidences of the relevance of uPAR-controlled oncolytic adenoviruses for the elimination of pancreatic cancer stem cells.

Role of drug-dependent transporter modulation on the chemosensitivity of cholangiocarcinoma Role of drug-dependent transporter modulation on the chemosensitivity of cholangiocarcinoma

Background/Objectives: YAT2150 is a first-in-class antiplasmodial compound that has been recently proposed as a new interesting drug for malaria therapy. Methods/Results: The fluorescence of YAT2150 rapidly increases upon its entry into Plasmodium, a property that can be of use for the design of highly sensitive diagnostic approaches. YAT2150 blocks the in vitro development of the ookinete stage of Plasmodium and, when added to an infected blood meal, inhibits oocyst formation in the mosquito. Thus, the compound could possibly contribute to future transmission-blocking antimalarial strategies. Cell influx/efflux studies in Caco-2 cells suggest that YAT2150 is internalized by endocytosis and also through the OATP2B1 transporter, whereas its main export route would be via OSTα. YAT2150 has an overall favorable drug metabolism and pharmacokinetics profile, and its moderate cytotoxicity can be significantly reduced upon encapsulation in immunoliposomes, which leads to a dramatic increase in the drug selectivity index to values close to 1000. Although YAT2150 binds amyloid-forming peptides, its in vitro fluorescence emission is stronger upon association with peptides that form amorphous aggregates, suggesting that regions enriched in unstructured proteins are the preferential binding sites of the drug inside Plasmodium cells. The reduction of protein aggregation in the parasite after YAT2150 treatment, which has been suggested to be directly related to the drug’s mode of action, is also observed following treatment with quinoline antimalarials like chloroquine and primaquine. Conclusions: Altogether, the data presented here indicate that YAT2150 can represent the spearhead of a new family of compounds for malaria diagnosis and therapy due to its presumed novel mode of action based on the interaction with functional protein aggregates in the pathogen.