Acquired resistance to therapy is a major obstacle in clinical oncology, and little is known about the contributing mechanisms of the host response to therapy. Here, we show that the proinflammatory cytokine IL1b is overexpressed in response to paclitaxel chemotherapy in macrophages, subsequently promoting the invasive properties of malignant cells. In accordance, blocking IL1b, or its receptor, using either genetic or pharmacologic approach, results in slight retardation of primary tumor growth; however, it accelerates metastasis spread. Tumors from mice treated with combined therapy of paclitaxel and the IL1 receptor antagonist anakinra exhibit increased number of M2 macrophages and vessel leakiness when compared with paclitaxel monotherapy-treated mice, indicating a prometastatic role of M2 macrophages in the IL1b-deprived microenvironment. Taken together, these findings demonstrate the dual effects of blocking the IL1 pathway on tumor growth. Accordingly, treatments using "add-on" drugs to conventional therapy should be investigated in appropriate tumor models consisting of primary tumors and their metastases. Mol Cancer Ther; 14(6); 1385-94. Ó2015 AACR.

Polyadenylation of RNA is a posttranscriptional modification that can play two somewhat opposite roles: stable polyadenylation of RNA encoded in the nuclear genomes of eukaryote cells contributes to nuclear export, translation initiation, and possibly transcript longevity as well. Conversely, transient polyadenylation targets RNA molecules to rapid exonucleolytic degradation. The latter role has been shown to take place in prokaryotes and organelles, as well as the nucleus of eukaryotic cells. Here we present evidence of hetero-and homopolymeric adenylation of truncated RNA molecules within the cytoplasm of human cells. RNAi-mediated silencing of the major RNA decay machinery of the cell resulted in the accumulation of these polyadenylated RNA fragments, indicating that they are degradation intermediates. Together, these results suggest that a mechanism of RNA decay, involving transient polyadenylation, is present in the cytoplasm of human cells.exosome | heteropolymeric tails | RNA polyadenylation R NA polyadenylation occurs throughout the biological world.Stable poly(A) is associated with the mature 3′ end of most mRNAs encoded in the nuclear genome of eukaryotes. It is important for nuclear export and efficient translation initiation and may also contribute to transcript longevity (1). In turn, mRNA degradation in the cytoplasm usually initiates with deadenylation of the stable poly(A) tail, followed by either further degradation of the mRNA body by the exosome (3′-5′ pathway) or removal of the 5′ cap and subsequent 5′-3′ degradation by hXrn1 (exoribonuclease 1; 5′-3′ pathway) (2-4).Unlike stable poly(A), transient poly(A) is not associated with the mature 3′ end of the transcript. RNA decay pathways that use transient poly(A) include a stage in which poly(A) or poly (A)-rich tails are added to the 3′ ends of truncated degradation intermediates and are believed to assist exoribonucleases in their rapid degradation. As the tail addition can occur after endonucleolytic cleavage of the RNA or repetitive adenylation and 3′-5′ digestion, it often appears to be at "internal" positions relative to the full RNA sequence (5, 6). The term "transient" is used because the short-lived tail is degraded along with the RNA fragment. Transient poly(A) was first disclosed in Escherichia coli and then in additional bacteria, organelles, archaea and, eventually, in yeast and human nuclei (4,5,(7)(8)(9). In all systems in which truncated, polyadenylated RNA fragments were initially detected, they were later found to be correlated to poly(A)-assisted RNA decay (4,7,8).In yeast nuclei, transient poly(A) was found to play a role in RNA quality control wherein polyadenylation, initiated by the TRAMP complex, targets incorrectly folded tRNA molecules to degradation by the nuclear exosome (10, 11). In human cells, cotranscriptionally cleaved 3′ regions of an introduced β-globin gene and a class of short, highly unstable RNAs, dubbed PROMPTs (promoter upstream transcripts), were found to be adenylated and accumulated when the exosome wa...

Weekly gemcitabine therapy is the major treatment offered for patients with pancreatic adenocarcinoma cancer; however, relative resistance of tumor cells to chemotherapy, rapid regrowth, and metastasis are the main causes of death within a year. Recently, the daily continuous administration of chemotherapy in low doses – called metronomic chemotherapy (MC) – has been shown to inhibit primary tumor growth and delay metastases in several tumor types; however, its use as a single therapy is still in question due to its moderate therapeutic benefit. Here, we show that the combination of weekly gemcitabine with MC of the same drug delays tumor regrowth and inhibits metastasis in mice implanted orthotopically with pancreatic tumors. We further demonstrate that weekly gemcitabine, but not continuous MC gemcitabine or the combination of the two drug regimens, promotes rebound myeloid-derived suppressor cell (MDSC) mobilization and increases angiogenesis in this tumor model. Furthermore, Bv8 is highly expressed in MDSCs colonizing pancreatic tumors in mice treated with weekly gemcitabine compared to MC gemcitabine or the combination of the two regimens. Blocking Bv8 with antibodies in weekly gemcitabine-treated mice results in a significant reduction in tumor regrowth, angiogenesis, and metastasis. Overall, our results suggest that pro-tumorigenic effects induced by weekly gemcitabine are mediated in part by MDSCs expressing Bv8. Therefore, both Bv8 inhibition and MC can be used as legitimate 'add-on' treatments for preventing post-chemotherapy pancreatic cancer recurrence, progression, and metastasis following weekly gemcitabine therapy.

Acute chemotherapy can induce rapid bone-marrow derived pro-angiogenic cell (BMDC) mobilization and tumor homing, contributing to tumor regrowth. To study the contribution of tumor cells to tumor regrowth following therapy, we focused on tumor-derived microparticles (TMPs). EMT/6 murine-mammary carcinoma cells exposed to paclitaxel chemotherapy exhibited an increased number of TMPs and significantly altered their angiogenic properties. Similarly, breast cancer patients had increased levels of plasma MUC-1 1 TMPs following chemotherapy. In addition, TMPs from cells exposed to paclitaxel induced higher BMDC mobilization and colonization, but had no increased effect on angiogenesis in Matrigel plugs and tumors than TMPs from untreated cells. Since TMPs abundantly express osteopontin, a protein known to participate in BMDC trafficking, the impact of osteopontin-depleted TMPs on BMDC mobilization, colonization, and tumor angiogenesis was examined. Although EMT/6 tumors grown in mice inoculated with osteopontin-depleted TMPs had lower numbers of BMDC infiltration and microvessel density when compared with EMT/6 tumors grown in mice inoculated with wild-type TMPs, no significant difference in tumor growth was seen between the two groups. However, when BMDCs from paclitaxel-treated mice were injected into wild-type EMT/6-bearing mice, a substantial increase in tumor growth and BMDC infiltration was detected compared to osteopontin-depleted EMT/6-bearing mice injected with BMDCs from paclitaxel-treated mice. Collectively, our results suggest that osteopontin expressed by TMPs play an important role in BMDC mobilization and colonization of tumors, but is not sufficient to enhance the angiogenic activity in tumors.

Pro-inflammatory cytokines in the tumor microenvironment are known for their ability to either inhibit or promote cancer progression. Here we evaluated the role of Interleukin-31 (IL31), a protein belonging to the pro-inflammatory IL-6 cytokine family which has been characterized in autoimmune disease, in tumorigenesis. We show that IL31 and its receptor, IL31RA, are highly expressed in various human and mouse cancer cell lines, as well as in tumor specimens from cancer patients. MC38 murine colon carcinoma cells depleted of IL31 exhibit an increase in invasive and migratory properties in vitro, effects that are reversed by supplementing the cells with exogenous IL31. In vivo, IL31-depleted MC38 tumor cells implanted to mice grow faster than control tumors. In contrast, MC38 tumor-bearing mice infused with recombinant IL31, exhibit a significant reduction in tumor growth than control mice. Furthermore, IL31 infusion reduces the number of metastatic lesions in the lungs of mice bearing 4T1 murine metastatic breast carcinoma. Lastly, injecting tumor-bearing, chemotherapy-treated mice with a long-lived IL31-IgG fusion protein reduces tumor growth, angiogenesis and pulmonary metastasis to a greater extent than when chemotherapy is used alone. The IL31 anti-tumor activity is explained, in part, by the anti-angiogenic effects demonstrated both in vitro and in vivo highlighting the potential use of IL31 as an anti-cancer drug.