The ectonucleotidases CD39 and CD73 hydrolyze extracellular adenosine triphosphate (ATP) and adenosine diphosphate (ADP) to generate adenosine, which binds to adenosine receptors and inhibits T-cell and natural killer (NK)-cell responses, thereby suppressing the immune system. The generation of adenosine via the CD39/CD73 pathway is recognized as a major mechanism of regulatory T cell (Treg) inhibited the proliferation of CD4 and CD8 T cells and the generation of cytotoxic effector CD8 T cells (CTL) in a CD39-and adenosine-dependent manner. Treatment with a CD39 inhibitor or blocking antibody alleviated the tumor-induced inhibition of CD4 and CD8 T-cell proliferation and increased CTL-and NK cell-mediated cytotoxicity. In conclusion, interfering with the CD39-adenosine pathway may represent a novel immunotherapeutic strategy for inhibiting tumor cell-mediated immunosuppression.

The proinflammatory cytokine Interleukin 17A (hereafter named IL–17A) or IL-17A producing cells are elevated in breast tumors environment and correlate with poor prognosis. Increased IL-17A is associated with ER(−) or triple negative tumors and reduced Disease Free Survival. However, the pathophysiological role of IL-17A in breast cancer remains unclear although several studies suggested its involvement in cancer cell dissemination. Here we demonstrated that a subset of breast tumors is infiltrated with IL-17A-producing cells. Increased IL-17A seems mainly associated to ER(−) and triple negative/basal-like tumors. Isolation of tumor infiltrating T lymphocytes (TILs) from breast cancer biopsies revealed that these cells secreted significant amounts of IL-17A. We further established that recombinant IL-17A recruits the MAPK pathway by upregulating phosphorylated ERK1/2 in human breast cancer cell lines thereby promoting proliferation and resistance to conventional chemotherapeutic agents such as docetaxel. We also confirmed here that recombinant IL-17A stimulates migration and invasion of breast cancer cells as previously reported. Importantly, TILs also induced tumor cell proliferation, chemoresistance and migration and treatment with IL-17A-neutralizing antibodies abrogated these effects. Altogether these results demonstrated the pathophysiological role of IL-17A-producing cell infiltrate in a subset of breast cancers. Therefore, IL-17A appears as potential therapeutic target for breast cancer.

Apart from microRNAs, little is known about the regulation of expression of non-coding RNAs in cancer. We investigated whether small nucleolar RNAs (snoRNAs) accumulation displayed specific signatures in acute myeloblastic and acute lymphoblastic leukemias. Using microarrays and high-throughput quantitative PCR (qPCR), we demonstrate here that snoRNA expression patterns are negatively altered in leukemic cells compared with controls. Interestingly, a specific signature was found in acute promyelocytic leukemia (APL) with ectopic expression of SNORD112-114 snoRNAs located at the DLK1-DIO3 locus. In vitro experiments carried out on APL blasts demonstrate that transcription of these snoRNAs was lost under all-trans retinoic acid-mediated differentiation and induced by enforced expression of the PML-RARalpha fusion protein in negative leukemic cell lines. Further experiments revealed that the SNORD114-1 (14q(II-1)) variant promoted cell growth through cell cycle modulation; its expression was implicated in the G0/G1 to S phase transition mediated by the Rb/p16 pathways. This study thus reports three important observations: (1) snoRNA regulation is different in normal cells compared with cancer cells; (2) a relationship exists between a chromosomal translocation and expression of snoRNA loci; and (3) snoRNA expression can affect Rb/p16 cell cycle regulation. Taken together, these data strongly suggest that snoRNAs have a role in cancer development.

The tumor immune microenvironment contributes to tumor initiation, progression, and response to therapy. Among the immune cell subsets that play a role in the tumor microenvironment, innate-like T cells that express T cell receptors composed of γ and δ chains (γδ T cells) are of particular interest. γδ T cells can contribute to the immune response against many tumor types (lymphoma, myeloma, melanoma, breast, colon, lung, ovary, and prostate cancer) directly through their cytotoxic activity and indirectly by stimulating or regulating the biological functions of other cell types required for the initiation and establishment of the anti-tumor immune response, such as dendritic cells and cytotoxic CD8+ T cells. However, the notion that tumor-infiltrating γδ T cells are a good prognostic marker in cancer was recently challenged by studies showing that the presence of these cells in the tumor microenvironment was associated with poor prognosis in both breast and colon cancer. These findings suggest that γδ T cells may also display pro-tumor activities. Indeed, breast tumor-infiltrating γδ T cells could exert an immunosuppressive activity by negatively regulating dendritic cell maturation. Furthermore, recent studies demonstrated that signals from the microenvironment, particularly cytokines, can confer some plasticity to γδ T cells and promote their differentiation into γδ T cells with regulatory functions. This review focuses on the current knowledge on the functional plasticity of γδ T cells and its effect on their anti-tumor activities. It also discusses the putative mechanisms underlying γδ T cell expansion, differentiation, and recruitment in the tumor microenvironment.

Pro-inflammatory IL-17 cytokines were initially described for their pathogenic role in chronic inflammatory diseases and subsequent accumulating evidence indicated their involvement in carcinogenesis. In the present study we report that IL-17A and IL-17E receptors subunits mRNA expressions are upregulated in breast cancers versus normal samples. IL-17E, which is undetectable in most normal breast tissues tested, seems more expressed in some tumors. Investigation of the molecular signaling following stimulation of human breast cancer cell lines with IL-17A and IL-17E showed that both cytokines induced the phosphorylation of c-RAF, ERK1/2 and p70 S6 Kinase were involved in the proliferation and survival of tumor cells. Accordingly, IL-17A and IL-17E promoted resistance to Docetaxel and failed to induce apoptosis as previously reported for IL-17E. Interestingly, we also revealed that both cytokines induced the generation of tumorogenic low molecular weight forms of cyclin E (LMW-E), which high levels correlated strongly with a poor survival in breast cancer patients. These results show for the first time some of the molecular pathways activated by IL-17A and IL-17E that may participate to their pro-oncogenic activity in breast cancers.

Interleukin 17B (IL-17B) is a pro-inflammatory cytokine that belongs to the IL-17 cytokines family and binds to IL-17 receptor B (IL-17RB). Here we found that high expression of IL-17B and IL-17RB is associated with poor prognosis in patients with breast cancer and that IL-17B expression upregulation is specifically associated with poorer survival in patients with basal-like breast cancer. We thus focused on IL-17B role in breast cancer by using luminal and triple negative (TN)/basal-like tumor cell lines. We found that IL-17B induces resistance to conventional chemotherapeutic agents. In vivo, IL-17B induced resistance to paclitaxel and treatment with an anti-IL-17RB neutralizing antibody completely restored breast tumor chemosensitivity, leading to tumor shrinkage. We next focused on the signaling pathways activated in human breast cancer cell lines upon incubation with IL-17B. We observed that IL-17B induces ERK1/2 pathway activation, leading to upregulation of anti-apoptotic proteins of the BCL-2 family. IL-17B-induced chemoresistance was completely abolished by incubation with PD98059, an inhibitor of the MAPK/ERK pathway, indicating that the ERK pathway plays a crucial role. Altogether our results emphasize the role of the IL-17B/IL-17RB signaling pathway in breast tumors and identify IL-17B and its receptor as attractive therapeutic targets for potentiating breast cancer chemotherapy.

Recombinant human IL-15 (rhIL-15) is one of the most promising cytokines for antitumor immunotherapy. In physiology IL-15 trans-presentation by accessory cells leads to pleiotropic activities, including activation of immune cells, such as NK cells. NK cells are largely involved in Ab-dependent cellular cytotoxicity mediated by therapeutic mAbs, such as rituximab, in chronic lymphocytic leukemia (CLL). Nevertheless, in CLL, Ab-dependent cellular cytotoxicity is relatively impaired by the low E:T ratio (NK/B leukemic cells). Thus, any strategy leading to an increase in NK cell number and activation status can offer new strategies for CLL treatment. To this end, we evaluated the effect of rhIL-15 on autologous NK cell stimulation in CLL samples. We show that rhIL-15 induces NK cell activation and proliferation, leading to improved B leukemic cell depletion. This phenomenon is significantly increased in the presence of anti-CD20 mAbs. In addition, the greater effect of obinutuzumab versus rituximab suggests a cooperative role between rhIL-15 signaling and CD16 signaling in the induction of NK cell proliferation. Moreover, rhIL-15–induced proliferation of autologous NK cells is strictly dependent on their interaction with B leukemic cells, identified in this study as new accessory cells for rhIL-15 trans-presentation. Thus, rhIL-15 is able to promote NK cell–based activity in Ab immunotherapy of CLL.

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