Current Cancer Drug Targets - Volume 15, Issue 5, 2015

The Notch signaling pathway is a highly conserved system that controls embryonic cell fate decisions and the maintenance of adult stem cells through affecting communication between adjacent cells. The pathway is linked to the development of various cancers owing to increased cell proliferation and tumor blood perfusion in addition to inhibition of apoptosis. Pharmaceutical agents that suppress overactive Notch signaling may be of benefit in the treatment of patients with various cancers. These targeted therapies confer several advantages over conventional anticancer therapies including reduced deleterious effects on normal cells. In this review, we explore the rationale for targeting the Notch signaling pathway in cancer along with different investigational strategies designed to block the pathway.

Aurora kinase A, B and C, are key regulators of mitosis and are over expressed in many of the human cancers, making them an ideal drug target for cancer chemotherapy. Currently, over a dozen of Aurora kinase inhibitors are in various phases of clinical development. The majority of the inhibitors (VX-680/MK-0457, PHA-739358, CYC116, SNS-314, AMG 900, AT-9283, SCH- 1473759, ABT-348, PF-03814735, R-763/AS-703569, KW-2449 and TAK-901) are pan-selective (isoform non-selective) and few are Aurora A (MLN8054, MLN8237, VX-689/MK5108 and ENMD 2076) and Aurora B (AZD1152 and GSK1070916) sub-type selective. Despite the intensive research efforts in the past decade, no Aurora kinase inhibitor has reached the market. Recent evidence suggests that the sub-type selective Aurora kinase A inhibitor could possess advantages over pan-selective Aurora inhibitors, by avoiding Aurora B mediated neutropenia. However, sub-type selective Aurora kinase A inhibitor design is very challenging due to the similarity in the active site among the isoforms. Structural biology and computational aspects pertaining to the design of Aurora kinase inhibitors were analyzed and found that a possible means to develop sub-type selective inhibitor is by targeting Aurora A specific residues (Leu215, Thr217 and Arg220) or Aurora B specific residues (Arg159, Glu161 and Lys164), near the solvent exposed region of the protein. Particularly, a useful strategy for the design of sub-type selective Aurora A inhibitor could be by targeting Thr217 residue as in the case of MLN8054. Further preclinical and clinical studies with the sub-type selective Aurora inhibitors could help bring them to the market for the treatment of cancer.

Cancer is fundamentally a genomic disease caused by mutations or rearrangements in the DNA or epigenetic machinery of a patient. An emerging field in cancer treatment targets key aberrations arising from the mutational landscape of an individual patient’s disease rather than employing a cancer-wide cytotoxic therapy approach. In prostate cancer in particular, where there is an observed variation in response to standard treatments between patients with disease of a similar pathological stage and grade, mutationdirected treatment may grow to be a viable tool for clinicians to tailor more effective treatments. This review will describe a number of mutations across multiple forms of cancer that have been successfully antagonised by targeted therapeutics including their identification, the development of targeted compounds to combat them and the development of resistance to these therapies. This review will continue to examine these same mutations in the treatment and management of prostate cancer; the prevalence of targetable mutations in prostate cancer, recent clinical trials of targeted-agents and the potential or limitations for their use.

Traditional therapy for cancer is subject to some evident obstacles, including low effectiveness, resistance, systemic complication, etc. Gold nanostructures responsive to near-infrared (NIR) light are attractive for non-invasive and targeted therapy because of their unique physical properties especially strong absorption and scattering, and high surface area-to-volume ratio as well as the ease of which their surface chemistry can be manipulated to enhance biocompatibility surface modification and functionalization. In this Review, the progress of photothermal therapy (PTT) as well as the targeted delivery of anticancer agents as the predominant applications of gold nanostructures is detailed, with a focus on imaging-guided therapy and optimizing operational parameters. The NIR light-controlled targeted delivery and/or photothermal ablation of gold nanostructures in the treatment of metastasis are also briefly discussed. These gold nanostructures pave the way for developing better therapeutic strategies of cancer.

The epidermal growth factor receptor-tyrosine kinase inhibitors (EGFRTKI), such as gefitinib and erlotinib have improved the survival of patients with nonsmall cell lung cancer (NSCLC). Unfortunately, acquired resistance will eventually develop in most patients who initially respond to the therapy. Currently known molecular mechanisms for such an acquired resistance may interpret only about 70% of clinical cases. In this study, using NSCLC cell model H1650, we constructed a gefitinib resistant cell line H1650GR through long term drug exposure with increased doses. RNA sequencing and whole genome SNP array were applied to investigate the transcriptome and genome alterations possibly involved in gefitinib resistance. By comparing the expression profiles between H1650GR and H1650 cells, we identified a large set of differentially expressed genes (DEGs), including FOXM1. In the PI3K/AKT pathway, AKT activity was predicted to be inhibited. However, genes that play important roles in gefitinib-induced apoptosis, including TP53, FOXO3 and BAD, were not up-regulated. Ingenuity Pathway Analysis (IPA) canonical pathway analysis showed that p53 signaling was inhibited in H1650GR cells, with down-regulation of pro-apoptosis genes FAS, PUMA, NOXA, and upregulation of anti-apoptosis genes BIRC5/Survivin. Besides, a large number of immune response-related genes were differently expressed, the role of which in gefitinib resistance requires further investigation. Whole genome copy number alterations (CNAs) were also analyzed and NOXA was located in the H1650GR unique copy number loss region, 18q21. Our results suggested that the much higher EGFR-TKI resistance in H1650GR may be produced by the integration of multi-aspect factors.

Background: Hepatocellular carcinoma (HCC) tends to develop in the liver when there is a high level of background inflammation (cirrhosis). Treatment options are limited and mainly based on systemic therapies such as anti-angiogenic drugs (e.g. sorafenib). Connective tissue growth factor (CTGF) is a matricellular protein involved in inflammation, tumour growth and angiogenesis. The aim of this study is to determine the expression of CTGF and hypoxia inducible factors (HIF) in HCC and to clarify its impact on relapse and survival. Material and Methods: Eligibility criteria for the study consisted of patients with a diagnosis of HCC, formalin-fixed and paraffin-embedded (FFPE) biopsy tissue, as well as relapse and available survival data. A tissue microarray was constructed from ≥70% tumoural sections. The expressions of CTGF, HIF1α and HIF2α were analysed by immunohistochemistry. The relationship between expression of CTGF/HIF1α and CTGF/HIF2α were analysed. Univariate and multivariate analyses were performed. Results: Fifty-three patients were screened; 39 patients were eligible for this study. Patients were treated with radical intent. At the end of follow up, 59% patients relapsed (28.2% locally, 10.3% multicentric liver relapse and 7.7% distant metastases). Estimated median disease-free survival (DFS) and overall survival (OS) were 23.4 (95%CI 7.18-39.66) and 38.6 months (95%CI 30.7-46.6), respectively. Expression of CTGF was: negative 23.1%, focal 48.7% and diffuse 23.1%. A non-statistically significant relationship between expression of CTGF and HIF was shown supporting an alternative pathway for CTGF expression in HCC. In multivariate analysis CTGF expression was an independent factor related to OS, with shorter survival in those patients with focal/diffuse CTGF expression (HR 2.46; 95%CI 1.18-5.15). Conclusions: Our results support that expression of CTGF is an independent factor associated with shorter OS in HCC. Further analysis of CTGF expression in a larger series of HCC patients is required to confirm CTGF as a prognostic biomarker in HCC.

Drug delivery systems are under intense investigation all around the world, especially in oncology research. Indeed, in some cases, like bone metastasis, nanodrugs may represent the last and best choice for both treatment and imaging of early cancer foci. Nuclear medicine has been using MDP labelled with 99mTc as radiopharmaceuticals for many years; however, their use as nanoradiopharmaceuticals is very innovative and creates a new way to establish radiopharmacy in this new scenario offered by nanotechnology. In this study we developed and tested nano-MDP-labelled with 99mTc in rats induced with bone cancer metastasis and the results showed that it may work in patients. However, some further experiments are required in order to initiate protocols in humans.