Here we present evidence that allows us to consider a combined therapy regimen comprising an autophagy inhibitor and a MAPK or NF-kB pathway inhibitor as a possible treatment strategy for pancreatic cancer.

Pancreatic cancer is an aggressive disease. Its incidence has increased over the last two decades. It is currently the fourth cause of death among cancers in the western world. Unfortunately, systemic chemotherapy still relies on just a few drugs which until now have produced unsatisfactory results. Gemcitabine (2'-2'-difluorodeoxycytidine) is currently the standard chemotherapy treatment at all stages of pancreatic adenocarcinoma. Survival benefit and clinical impact however remain moderate due to a high degree of intrinsic and acquired resistance. Autophagy plays an important role in cell death decision but can also protect cells from various apoptotic stimuli. We investigated the function of autophagy in pancreatic carcinoma cells, which are frequently insensitive to standard chemotherapeutic agents. Here, we demonstrate that autophagy is one of the mechanisms responsible for the refractory response of pancreatic tumors to gemcitabine. We present evidence in vitro and in vivo that proves autophagy plays a protective role in pancreatic ductal carcinoma cells, preventing them from entering the apoptotic pathway after stimulus with gemcitabine, thus contributing to treatment resistance. A better understanding of the role in the process may help in the discovery of new strategies to overcome tumor drug resistance in this aggressive disease.

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Sipunculans, a small phylum of coelomated marine worms closely related to polychaete annelids, lack a true circulatory system. We have previously shown that the sipunculan Themiste petricola can form a cellular clot, without congealing, of cell-free coelomic fluid. The clot is formed by the aggregation of large granular leukocytes (LGLs) and may serve not only haemostatic but immune functions, since dissimilar particles may become entrapped within it. We have now evaluated the capacity of a massive clot, induced in vitro by sea water contact, to stop coelomic fluid flow. We have further studied smaller clots induced on glass-slides either with or without the presence of bacteria placed for entrapment within the clot. The fate of clotting LGLs is cell death while forming a cohesive mass, although cytoplasmic and nuclear remnants are shed from the clot. These remnants and any bacteria that avoid clot entrapment or are detached from the clot are engulfed by non-clotting cells that include small granular leukocytes (SGLs) and large hyaline amebocytes (LHAs). Both cell types can be found other than in the clot but SGLs also occur around the clot edges heavily loaded with engulfed material. The cytoskeletal arrangement of SGLs evaluated with phalloidin-rhodamine correspond to motile cells and contrast with that of clotting LGLs that form a massive network of F-actin. Thus, the complementary roles between clotting LGLs and non-clotting SGLs and LHAs act a central immune strategy of Themiste petricola to deal with body wall injury and pathogen intrusion into the coelomic cavity.

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Chemotherapy aims to limit proliferation and induce apoptotic cell death in tumor cells. Owing to blockade of signaling pathways involved in cell survival and proliferation, nuclear factor kappaB (NF-kappaB) inhibitors can induce apoptosis in a number of hematological malignancies. The efficacy of conventional chemotherapeutic drugs, such as vincristine (VCR) and doxorubicine (DOX), may be enhanced with combined therapy based on NF-kappaB modulation. In this study, we evaluated the effect of caffeic acid phenylethyl ester (CAPE) and MG-132, two nonspecific NF-kappaB inhibitors, and conventional chemotherapeutics drugs DOX and VCR on cell proliferation and apoptosis induction on a lymphoblastoid B-cell line, PL104, established and characterized in our laboratory. CAPE and MG-132 treatment showed a strong antiproliferative effect accompanied by clear cell cycle deregulation and apoptosis induction. Doxorubicine and VCR showed antiproliferative effects similar to those of CAPE and MG-132, although the latter drugs showed an apoptotic rate two-fold higher than DOX and VCR. None of the four compounds showed cytotoxic effect on peripheral mononuclear cells from healthy volunteers. CAPE- and MG-132-treated bone marrow cells from patients with myeloid and lymphoid leukemias showed 69% (P < .001) and 25% decrease (P < .01) in cell proliferation and 42% and 34% (P < .01) apoptosis induction, respectively. Overall, our results indicate that CAPE and MG-132 had a strong and selective apoptotic effect on tumor cells that may be useful in future treatment of hematological neoplasias.

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