Killer-cell immunoglobulin-like receptors (KIR) are expressed by natural killer (NK) and effector T cells. Although KIR+ T cells accumulate in oncologic patients, their role in cancer immune response remains elusive. This study explored the role of KIR+CD8+ T cells in cancer immunosurveillance by analyzing their frequency at diagnosis in the blood of 249 patients (80 melanomas, 80 bladder cancers, and 89 ovarian cancers), their relationship with overall survival (OS) of patients, and their gene expression profiles. KIR2DL1+ CD8+ T cells expanded in the presence of HLA-C2-ligands in patients who survived, but it did not in patients who died. In contrast, presence of HLA-C1-ligands was associated with dose-dependent expansions of KIR2DL2/S2+ CD8+ T cells and with shorter OS. KIR interactions with their specific ligands profoundly impacted CD8+ T cell expression profiles, involving multiple signaling pathways, effector functions, the secretome, and consequently, the cellular microenvironment, which could impact their cancer immunosurveillance capacities. KIR2DL1/S1+ CD8+ T cells showed a gene expression signature related to efficient tumor immunosurveillance, whereas KIR2DL2/L3/S2+CD8+ T cells showed transcriptomic profiles related to suppressive anti-tumor responses. These results could be the basis for the discovery of new therapeutic targets so that the outcome of patients with cancer can be improved.

Protein kinase C (PKC) comprises a family of highly related serine/threonine protein kinases involved in multiple signaling pathways, which control cell proliferation, survival, and differentiation. The role of PKCα in cancer has been studied for many years. However, it has been impossible to establish whether PKCα acts as an oncogene or a tumor suppressor. Here, we analyzed the importance of PKCα in cellular processes such as proliferation, migration, or apoptosis by inhibiting its gene expression in a luminal A breast cancer cell line (MCF-7). Differential expression analysis and phospho-kinase arrays of PKCα-KD vs. PKCα-WT MCF-7 cells identified an essential set of proteins and oncogenic kinases of the JAK/STAT and PI3K/AKT pathways that were down-regulated, whereas IGF1R, ERK1/2, and p53 were up-regulated. In addition, unexpected genes related to the interferon pathway appeared down-regulated, while PLC, ERBB4, or PDGFA displayed up-regulated. The integration of this information clearly showed us the usefulness of inhibiting a multifunctional kinase-like PKCα in the first step to control the tumor phenotype. Then allowing us to design a possible selection of specific inhibitors for the unexpected up-regulated pathways to further provide a second step of treatment to inhibit the proliferation and migration of MCF-7 cells. The results of this study suggest that PKCα plays an oncogenic role in this type of breast cancer model. In addition, it reveals the signaling mode of PKCα at both gene expression and kinase activation. In this way, a wide range of proteins can implement a new strategy to fine-tune the control of crucial functions in these cells and pave the way for designing targeted cancer therapies.

Diffuse large B-cell lymphoma (DLBCL) refers to an aggressive lymphoma that arises from germinal center (GC) B cells, which differentiate into plasma cells to produce high-affinity antibodies. A total of 40% of patients with DLBCL relapse or are refractory to the conventional immunochemotherapy treatment, usually with fatal consequences. DLBCL is characterized by profound alterations in the epigenome, which is correlated with poor survival. The abnormal epigenetic landscape of DLBCL tumors is associated with a blockade in GC exit and differentiation programs, which are regulated by the transcription factor BCL6. This aberrant repression of BCL6 target genes is mediated by (1) increased DNA methylation and (2) the loss of acetylation of lysine 27 of histone 3 through the recruitment of histone deacetylase 3 (HDAC3). Therefore, we investigated the efficacy of the hypomethylating agent 5-azacitidine (5-aza) and a specific HDAC3 inhibitor (HDAC3i) against DLBCL. We found that the treatment of activated B cell-like and GC B cell-like DLBCL cells with 5-aza plus HDAC3i had a potent synergistic antitumor activity in vitro and in vivo, which was superior to the effect of each single drug or 5-aza combined with nonspecific HDACi and, importantly, was not associated with toxicity in normal T cells. We also demonstrated that, compared with that with each drug used as single agents, the combined 5-aza and HDAC3i treatment induced the epigenetic remodeling of DLBCL cells, which resulted in a more potent reexpression of differentiation genes, including XBP1 and ATF4. Our results highlight the importance of specifically targeting multiple layers of the epigenome to maximize the efficacy of epigenetic-based therapies.