Current Cancer Drug Targets - Volume 14, Issue 7, 2014

Malfunctions in membrane transporters or disruptions in signaling cascades induce resistance to chemotherapy in cancer cells resulting in treatment failure. To adjust the genetic alterations leading to these cellular protective measures, dissection and verification of the contributing routes would be required. In justification of knockdown of the key genes, RNA interference provides a reliable probing tool, enabling exploration of phenotypic manifestation of targeted genes. Investigation of the non-transporter targets, predominantly oncogenes and tumor suppressor genes, by means of small interfering RNA with the aim to re-sensitize cancer cells to therapeutics will be discussed in this review.

CD40 is a co-stimulatory molecule belonging to the tumor necrosis factor superfamily and is essential in activation of dendritic cells. Dendritic cells (DCs) are antigen-presenting cells capable of initiating cytotoxic T-lymphocyte immune response against cancer cells. However, there are few studies on the characterization of DCs in cancer, specifically their expression of CD40, despite its implication in cancer immunotherapy. We reviewed available data on the expression of CD40 on DCs in various cancers, and its implications for cancer immunotherapy. A systematic review on CD40 expression on DCs in cancer was performed with reference to preferred reporting items for systematic reviews and meta-analyses (PRISMA). Studies that satisfied the inclusion and exclusion criteria were 21 out of 927. Variations in type and status of the cancers, source of DCs and methodology for detecting CD40 expression amongst the studies resulted in contrasting results. DCs generally expressed low CD40 in tumor infiltrating DCs (tiDCs), in DCs derived by in vitro culture from blood monocytes using cytokine stimulation (MoDCs) and in DCs exposed in vitro to tumor cells lines; the studies suggested that CD40 expression in DCs is impaired in cancer particularly in metastatic disease. However, DCs identified in fresh peripheral blood mononuclear cells (PBMC) expressed higher numbers of CD40 positive cells in some cancer patients, which could be due to tumor-derived factors leading to partially-stimulated DCs. The results provide evidence that some cancer patients may show partial systemic DC activation and expression of increased CD40 in response to the presence of tumor but that such activity may become abortive in the presence of factors produced by the tumor. This review has thus identified key papers on CD40 expression on DCs in various cancers and discusses the limitations and contrasting results of these studies in relation to variations in methodology. The results highlight the need for further studies on the role of CD40-CD40 ligand pathway to inform cancer treatment.

Evidences have demonstrated key mediatory roles of microRNA-205 (miR-205) in normal physiology and its aberrant expression in many cancers. Indeed, miR-205 has been identified as both a tumour suppressive and oncogenic miRNA playing crucial roles in tumourigenesis through regulating different cellular pathways such as cell survival, apoptosis, angiogenesis and metastasis. As a tumour suppressor, miR-205 acts as an inhibitor of cell proliferation, migration and invasion. On the other hand, as an oncogene, miR-205 promotes tumour initiation and development. All these functions act through different target genes in various types of cancers. Also, miR-205 displays potential as a therapeutic target for different cancers. To conclude, miR-205 has important clinical and pathological correlations in different cancers and may act as a diagnostic and prognostic marker as well as new molecular target for cancer therapy.

Scaffold-based analogs of cinnamic acid benzyl amide (CABA) exhibit pleiotropic effects in cancer cells, and their exact molecular mechanism of action is under investigation. The present study is part of our systemic analysis of interactions of CABA analogs with their molecular targets. These compounds were shown to inhibit Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) and JAK2/signal transducer and activator of transcription 5 (STAT5) signaling and thus are attractive scaffolds for anticancer drug design. To identify the potential mechanisms of action of this class of compounds, direct interactions of the selected CABA analogs with JAK2 kinase were examined. Inhibition of JAK2 enzymatic activity was assessed, and molecular modeling studies of selected compounds—(E)-2-cyano-N-[(S)-1-phenylethyl]-3-(pyridin-2-yl)acrylamide (WP1065), (E)-2-cyano-N-[(S)-1-phenylbutyl]- 3-(3-bromopyridin-2-yl)acrylamide (WP1130), and (E)-2-cyano-N-[(S)-1,4-diphenylbutyl]-3-(3-bromopyridin-2-yl)acrylamide (WP1702)—in the JAK2 kinase domain were used to support interpretation of the experimental data. Our results indicated that the tested CABA analogs are nonclassical inhibitors of activated (phosphorylated) JAK2, although markedly weaker than clinically tested ATP-competitive JAK2 inhibitors. Relatively small structural changes in the studied compounds affected interactions with JAK2, and their mode of action ranged from allosteric-noncompetitive to bisubstratecompetitive. These results demonstrated that direct inhibition of JAK2 enzymatic activity by the WP1065 (half-maximal inhibitory concentration [IC50] = 14.8 μM), WP1130 (IC50 = 3.8 μM), and WP1702 (IC50 = 2.9 μM) potentially contributes, albeit minimally, to suppression of the JAK2/STAT signaling pathways in cancer cells and that additional specific structural modifications may amplify JAK2-inhibitory effects.

Cysteine-rich motor neuron1 protein (CRIM1), a novel antagonist of bone morphogenetic proteins (BMPs), is reported to regulate the processing of BMPs preprotein into mature protein and the delivery of BMPs to the cell surface. Previous studies have shown that CRIM1 is an important player in regulating placental development, organogenesis, angiogenesis and kidney disease. Here, we propose that CRIM1 is a potential risk factor in cancer progression and metastasis. The epithelial-mesenchymal transition (EMT), which is characterized by the loss of epithelial phenotype and the acquisition of mesenchymal characteristics, is closely associated with invasion and metastasis of tumors. At the same time, it is hard for us to ignore the importance of angiogenesis in the genesis and progression of cancer. In this review we summarized the construction and previous researches of CRIM1. Furthermore, as it may be involved in tumor development and progression through its potential role in the EMT, capillary formation and angiogenesis maintenance, we proposed for the first time that CRIM1 may be a cancer related factor.

miRNAs are non-coding RNA molecules; their deregulations may contribute to cancer pathogenesis. However, the mechanisms of how miRNA dysfunction contributes to the lymphomagenesis of diffuse large B-cell lymphoma (DLBCL) are not well established. In this study, we analyzed the expression of miR-224 in four DLBCL cell lines and 168 patients’ specimens. We found that the expression of miR-224 in DLBCL was down-regulated compared with normal B-cell but was not statistically different between the germinal center B-cell-like-type and the activated B-cell-like-type. Using bioinformatics prediction and luciferase report assays, we demonstrated that miR-224 directly down-regulated CD59 expression by binding to its 3’-untranslated region. We also used immunohistochemical staining of CD59 in human DLBCL specimens and analyzed the relationship between the expression of miR-224, CD59 and the overall/progress-free survival of DLBCL patients who were uniformly treated with rituximab,cyclophosphamide, adriamycin, vincristine, and prednisone (R-CHOP). We found that miR-224 may contribute to DLBCL pathogenesis. Most importantly, the expression of miR-224 and CD59 can predict the response and outcome of DLBCL patients treated with R-CHOP.

Background and Aim: Inhibition of HSP90 is a potential strategy to treat pancreatic cancer (PC), since many client proteins of HSP90 are found to be over-expressed and/or genetically mutated in PC. These client proteins directly participate in the modulation of proliferation and aggravation of PC. Our previous works led to Y306zh as a novel and potent HSP90 inhibitor. In this study we further investigated the mode of actions of Y306zh as an anti-PC agent. Materials and Methods: The binding affinity of Y306zh towards HSP90 was analyzed by fluorescence polarization assay. The anti-proliferative activities and molecular mechanism of Y306zh were investigated in human PC cell lines and Miapaca2 xenograft model. Results: Y306zh binds tightly to the NH2-terminus of HSP90 with an IC50 of 85 nM, and this causes ATP incapable to attach to the same binding site, and disrupts HSP90-p23 association. Y306zh also induces the expression of HSP70, recruits the complex of CHIP, HSP70 and HSP90, and eventually results in the degradation of HSP90 client proteins (EGFR, AKT, C-RAF and CDK4) via proteasomal pathway. Amazingly, coincident with the molecular mechanism, Y306zh also inhibits the proliferation of PC cells through G2/M phase arrest, but appears to be totally insensitive to normal mammalian cells. Furthermore, Y306zh effectively inhibits tumor growth of Mia-paca2 xenograft mice without any obvious effect on body weight. Conclusions: Y306zh, a novel HSP90 inhibitor, interrupts ATP binding to HSP90 and disrupts HSP90-p23 interaction, and eventually inhibits the growth of PC cells.